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Turtle Sandwich Standard Model

Turtle Sandwich Standard Model

https://www.xkcd.com/2301

https://www.explainxkcd.com/wiki/index.php/2301:_Turtle_Sandwich_Standard_Model

[A two-by-two grid, with a piece of bread next to the top left cell; a turtle shell next to the bottom left cell; lettuce, cheese, and tomato above the top left cell; and an turtle head enclosed in a circle above the top right cell.] [Top left cell: an image of a sandwich.] ✔ CONFIRMED [Top right cell: an image of a shell-less turtle sandwiched between two slices of bread.] (?) [Bottom left cell: an image of a turtle shell housing lettuce, cheese, and tomato - the contents of a sandwich.] (?) [Bottom right cell: an image of a turtle.] ✔ CONFIRMED [Caption below the panel] Our lab is working to detect the two missing pieces of the turtle-sandwich standard model.

This comic references particle physics. The Standard Model of physics explains the base particles and fields that make up the universe. The elementary fermions of the standard model can be laid out in a 3×4 grid, with three " generations " of matter, each containing a quark with charge +⅔, a quark with charge -⅓, a lepton with charge -1, and a neutrino with charge 0. The first generation contains the familiar up and down quarks, which make protons and neutrons, the electron, and the electron neutrino. Each succeeding generation of matter is more massive than the one before, and only the first generation of particles occurs naturally on Earth; the others have only been created and identified in particle accelerator experiments (although they also arguably exist in various extreme places around the universe; for example, the strange quark is suspected to be a component of the denser parts of neutron stars). Quarks were initially proposed by Murray Gell-Mann to simplify the " particle zoo " that physicists were discovering. He found that the twenty-five or so mesons and hadrons that were known at that time could be organized into what he called the " eightfold way " by just three properties: spin , charge, and what he called " strangeness ". He proposed that three quarks (and their corresponding antiquarks) governed these properties. His chart had an empty space for what he called the omega baryon , and when a particle of the properties he predicted (including its mass) was discovered, his model received a lot of support. The quark model was eventually extended to include six quarks, and as with the eightfold way, one of the lines of evidence in favor of what became known as the Standard Model is that it predicted the existence and masses of several particles, which have since been confirmed; the top quark 's mass was predicted in 1973, and experimentally verified in 1995, for example, and on the gauge boson side of the chart, the Higgs boson was discovered in 2012. In this comic strip, sandwiches (lettuce, cheese, tomato, and possibly other fillings, surrounded by bread) and turtles (an aquatic reptile which wears an armored shell) are likewise proposed to not be "elementary" entities, but in fact combinations of 4 elementary parts, namely bread, fillings, reptile, and shell. The narrator's lab is looking for the hypothesized "bread-shelled turtle" and "shell-coated sandwich". In fiction, turtles' shells are often depicted as articles of clothing which they can remove at will, but in the real world, the shell is a part of the turtle's skeleton, so unless the narrator's lab is willing to commit extremely invasive surgery, they will never find a bread-shelled turtle, although they could much more easily take the shell of a dead turtle and put some sandwich fillings inside. The failure to detect the bread-shelled turtle could be taken as evidence that the turtle-sandwich standard model is flawed -- perhaps turtles and sandwiches are elementary entities, or perhaps the elementary entities that make them are much smaller than is proposed here. There is also the small matter that there are things besides sandwiches and turtles in the universe [ citation needed ] . Alternatively, it could be taken as evidence that the bread-shelled turtle has an extremely high energy, and so does not exist under typical conditions of our universe. This might be analogous to magnetic monopoles ; we would know one if and when we saw one (and many experiments have sought them out), and we believe we know how they would behave, but no such particle has ever been verifiably detected or created. In the same vein, the lack of observation could be due to the instability of the arrangements. Turtleshell-turtle assemblies can last for more than 100 years, while bread-filling assemblies are indefinitely stable under sufficiently low energies . The two other arrangements may simply be formed rarely, and have a relatively short half-life. The title text introduces more particle physics jargon, proposing that the "top and bottom" parts of the bread and/or shell have distinct " flavors ", and that there may be "strange" and "charm" variants as well (a reference to the higher-generation quarks -- strange and charm in the second generation, and top and bottom in the third). Unlike the turtle-sandwich standard model, there are no particles predicted by our Standard Model that have not yet been detected; however, there are several gaps between the pure Standard Model and what we observe in reality, most notably the existence of gravity and the apparent asymmetry between the amounts of matter and antimatter in the universe. For this reason, the Standard Model is generally considered to be somehow incomplete. [A two-by-two grid, with a piece of bread next to the top left cell; a turtle shell next to the bottom left cell; lettuce, cheese, and tomato above the top left cell; and an turtle head enclosed in a circle above the top right cell.] [Top left cell: an image of a sandwich.] ✔ CONFIRMED [Top right cell: an image of a shell-less turtle sandwiched between two slices of bread.] (?) [Bottom left cell: an image of a turtle shell housing lettuce, cheese, and tomato - the contents of a sandwich.] (?) [Bottom right cell: an image of a turtle.] ✔ CONFIRMED [Caption below the panel] Our lab is working to detect the two missing pieces of the turtle-sandwich standard model.

2020 Google Trends

2020 Google Trends

https://www.xkcd.com/2302

https://www.explainxkcd.com/wiki/index.php/2302:_2020_Google_Trends

[A line chart plotting the popularity of various search terms from May 2019 through April 2020: sewing machine (blue line), webcam (red), Andrew Cuomo (yellow), flour (green), and pangolin (purple). The yellow line starts at the bottom of the chart and rises about halfway up at the end of March 2020 before decaying to about 20% by the end of April. The purple line starts at the bottom of the chart and has a small lump in February 2020 and a slightly bigger lump in March 2020 before trending back down. The blue line starts at about 10% up the chart and then spikes up to 50% at the beginning of April before decaying to 40% at the end of April. The red line starts at about 20% up the chart, has a small lump in September 2019, and then jumps up to 40% in March 2020 before trending back down. The green line starts at about 30% up the chart, has a small lump in December 2019, and then spikes up to the top of the chart at the end of March 2020.] [Caption below comic:] I want to show someone from 2019 this Google Trends graph and watch them try to guess what happened in 2020.

This comic is another comic in a series of comics related to the COVID-19 pandemic . Randall wants to go back in time to show a 2019 person a Google Trends graph , showing massive spikes in a group of search terms, all around the same time. Some of the terms (flour, webcam, sewing machine) had fairly steady popularity, then rapidly jumped higher. Others (pangolin, Andrew Cuomo) were barely searched for at all until they suddenly became items of intense interest. The joke is that, without context, it would be impossible to guess what caused these simultaneous spikes, and the pattern would seem completely random. A person might guess that there was a single event that drove all of these searches, but it would be difficult to speculate what that might be. All of these trends are presumably due to the COVID-19 pandemic. The title text is a possible "guess" by the 2019 person for these search terms having an increase together: a YouTube craze of exotic animals (which includes pangolins) in homemade aprons (possibly made with the help of sewing machines) hosting baking shows which leads to a response by New York governor Andrew Cuomo. This is not correct. [ citation needed ] A recent prior comic that touches on the past's possible views on the present situation from limited information was 2280: 2010 and 2020 . In that case, the relative costs of cryptocurrency and hygiene supplies was considered unremarkable by a 2010 person because (unbeknownst to him) the price of both had skyrocketed. [A line chart plotting the popularity of various search terms from May 2019 through April 2020: sewing machine (blue line), webcam (red), Andrew Cuomo (yellow), flour (green), and pangolin (purple). The yellow line starts at the bottom of the chart and rises about halfway up at the end of March 2020 before decaying to about 20% by the end of April. The purple line starts at the bottom of the chart and has a small lump in February 2020 and a slightly bigger lump in March 2020 before trending back down. The blue line starts at about 10% up the chart and then spikes up to 50% at the beginning of April before decaying to 40% at the end of April. The red line starts at about 20% up the chart, has a small lump in September 2019, and then jumps up to 40% in March 2020 before trending back down. The green line starts at about 30% up the chart, has a small lump in December 2019, and then spikes up to the top of the chart at the end of March 2020.] [Caption below comic:] I want to show someone from 2019 this Google Trends graph and watch them try to guess what happened in 2020.

Error Types

Error Types

https://www.xkcd.com/2303

https://www.explainxkcd.com/wiki/index.php/2303:_Error_Types

[A list with nine entries. The left side has 9 types of errors numbered with Roman numerals. The right side has a description of each type of error:] Type I Error: False positive Type II Error: False negative Type III Error: True positive for incorrect reasons Type IV Error: True negative for incorrect reasons Type V Error: Incorrect result which leads you to a correct conclusion due to unrelated errors Type VI Error: Correct result which you interpret wrong Type VII Error: Incorrect result which produces a cool graph Type VIII Error: Incorrect result which sparks further research and the development of new tools which reveal the flaw in the original results while producing novel correct results Type IX Error: The Rise of Skywalker

This comic is another comic in a series of comics related to the 2020 pandemic of the coronavirus SARS-CoV-2 , which causes COVID-19 . The comic is inspired by the COVID-19 pandemic, as there is a lot of medical testing for the disease being done, including detection of the virus itself, usually by qPCR, or of antibodies present in people who have had the disease (sometimes unknowingly). The quality of these tests is often mediocre and never perfect, leading to discussion of different types of errors that can occur, including "false positives" (calling presence of the virus/antibodies when they are not really there) or false negatives (failing to see the virus/antibodies which are present). The comic is riffing on Type I and type II errors , also known as "false positive" and "false negative", respectively. The first two rows of the comic's table are correct definitions for established terms in statistics. Further rows contain suggestions for new terminology. [A list with nine entries. The left side has 9 types of errors numbered with Roman numerals. The right side has a description of each type of error:] Type I Error: False positive Type II Error: False negative Type III Error: True positive for incorrect reasons Type IV Error: True negative for incorrect reasons Type V Error: Incorrect result which leads you to a correct conclusion due to unrelated errors Type VI Error: Correct result which you interpret wrong Type VII Error: Incorrect result which produces a cool graph Type VIII Error: Incorrect result which sparks further research and the development of new tools which reveal the flaw in the original results while producing novel correct results Type IX Error: The Rise of Skywalker

Preprint

Preprint

https://www.xkcd.com/2304

https://www.explainxkcd.com/wiki/index.php/2304:_Preprint

[Blondie as a newscaster is sitting at a desk. To the right is a screen with text, the bottom word is a thin line making the letters white. Just above her head is what she says as her opening line for her news story. But above this text, is more text which have been grayed out and scribbled over. This are three other alternative opening lines which she did not use, indicating revisions to her script.] Blondie [gray and scribbled out]: According to a new preprint… Blondie [gray and scribbled out]: …An unpublished study… Blondie [gray and scribbled out]: According to a new paper uploaded to a preprint server but which has not undergone peer review… Blondie: According to a new PDF… Inset graphic: Breaking news [Beneath the panel is a long caption consisting of an underlined headline with three bulleted points beneath it:] Benefits of just saying "a PDF": Avoids implications about publication status Immediately raises questions about author(s) Still implies "this document was probably prepared by a professional, because no normal human trying to communicate in 2020 would choose this ridiculous format."

This comic is about how media reports non- peer-reviewed research papers. The newscaster depicted is attempting to report breaking news based on information in a study; however, the study in question has not been formally published. This leads to uncertainty on the part of either the newscaster, Blondie , or her scriptwriters as they try to determine how to refer to this study, represented here by alternative introduction lines being scribbled out. Randall suggests that, instead of explaining that the paper was in preprint , or unpublished or submitted to a preprint server and not peer-reviewed, the newscaster could simply say it was a PDF . PDF (Portable Document Format) is a file format for documents developed by Adobe to be used independent of application software, hardware and operating systems. Randall proceeds to lists several benefits of using "PDF": The title text makes fun of what is incorrectly believed to be the official name of PDF; it is now an open international standard (ISO 32000-1), and the only PDF files that are "Adobe Acrobat files" or "Adobe PDF" files are those created using Adobe Systems' software. Further, Adobe does not use the ® designation in conjunction with PDF. (See Adobe Trademark Guidelines, 1 Nov. 2014 ) Adobe trademark guidelines were also made fun of here . Since so many applications can create and even edit PDF files, implying a connection with Adobe every time someone talks about one is preposterous, and one could sarcastically pronounce the registered trademark symbol to show contempt for the fact that it is a registered trademark. This comic was possibly produced in response to the preprint study "COVID-19 Antibody Seroprevalence in Santa Clara County, California" , Bendavid et al, which was posted online in mid-April 2020 before peer review. The authors of the paper went on a media blitz immediately after posting it, appearing on major cable news networks and writing editorials in major publications, claiming that their results show that COVID-19 is not nearly as bad as thought and that most people are already immune to it. Other scientists have pointed out that, if the very high false-positive rate of the test used and the sample bias of their methodology (testing only people who self-report as sick) are properly considered in the analysis, the data collected is such poor quality as to be meaningless, with properly applied error bars on the number of actual cases in the general population extending below 0. Nonetheless, many less-scientifically-literate politicians, media figures, and protest groups continue to use the much-criticized study as proof that COVID-19 should not be considered an emergency, and that quarantine measures should be cancelled. As of May 11 2020, the study has still not passed peer review, nor undergone any revisions since the first posting. [Blondie as a newscaster is sitting at a desk. To the right is a screen with text, the bottom word is a thin line making the letters white. Just above her head is what she says as her opening line for her news story. But above this text, is more text which have been grayed out and scribbled over. This are three other alternative opening lines which she did not use, indicating revisions to her script.] Blondie [gray and scribbled out]: According to a new preprint… Blondie [gray and scribbled out]: …An unpublished study… Blondie [gray and scribbled out]: According to a new paper uploaded to a preprint server but which has not undergone peer review… Blondie: According to a new PDF… Inset graphic: Breaking news [Beneath the panel is a long caption consisting of an underlined headline with three bulleted points beneath it:] Benefits of just saying "a PDF": Avoids implications about publication status Immediately raises questions about author(s) Still implies "this document was probably prepared by a professional, because no normal human trying to communicate in 2020 would choose this ridiculous format."

Coronavirus Polling

Coronavirus Polling

https://www.xkcd.com/2305

https://www.explainxkcd.com/wiki/index.php/2305:_Coronavirus_Polling

[A panel only with text. At the top there is three paragraphs of explanatory text. Below that is a paragraph in smaller gray font with link to sources. Below that there are two columns of poll results, each with a heading. There are six polls in the left and seven polls in the right column. Instead of a bulleted list, each poll has its percent that agrees given to the left of the statement, which is thus aligned to the right of this percentage. At the end of each statement there is a reference in brackets in gray font.] It's hard to get people to agree on anything in polls. But we agree about the coronavirus. Here's how Americans feel about COVID-19, along with other topics that get similar levels of agreement for comparison. Compiled with help from HuffPost polling editor Ariel Edwards-Levy. Sources: xkcd.com/2305/sources [Left column:] Recent coronavirus polls 86% say "stay-at-home orders are responsible government policies that are saving lives" rather than "an over-reaction" (ABC/Ipsos) 85% oppose reopening schools (NPR/Marist) 91% oppose resuming big sporting events (NPR/M.) 85% trust local health officials and health care workers (Axios/Ipsos) 93% are trying to maintain 6-foot distances while in public (Axios/Ipsos) 81% say Americans should continue to social distance for as long as is needed to stop the Coronavirus even if it means continued damage to the economy (Politico/Morning Consult) [Right column:] Other polls 81% enjoy apple pie (HuffPost/YouGov) 76% feel positively about kittens (HuffPost/YouGov) 84% have a favorable impression of Tom Hanks (Ipsos 2018) 89% say fair elections are important to democracy (Pew) 86% feel positively toward Betty White (Ipsos 2011) 86% do not trust Kim Jong-Un to do the right thing (Pew 2019) 64% are concerned about the emergence of "murder hornets" (YouGov)

This comic is another comic in a series of comics related to the COVID-19 pandemic . The comic compares opinion polling of COVID-19 related topics to polling of other, mostly unrelated topics. The American public often tends to be sharply divided about major political and social issues, but polling shows that the country is remarkably united about the dangers posed by the COVID-19 and the measures necessary to prevent its spread. This is notable, because responses to this pandemic have significant political and economic implications, which usually results in major division and distrust. The poll results also contradict the extensive news coverage of notable anti-lockdown protests prominent in many major cities; by implication, this comic is arguing that such protests are unrepresentative and disproportionately covered. Or else that this vocal and demonstrative minority is almost the only group making their opinion public in such a newsworthy manner. To put these majority opinions in perspective, polls on other topics are shown with similar but slightly smaller high percentages of likemindedness but on extremely uncontroversial questions [ citation needed ] such as liking apple pie or Tom Hanks, or the importance of elections to democracy. The title text refers to the chapter "How To Win an Election" in Munroe's book How To: Absurd Scientific Advice for Common Real-World Problems , in which a similar set of near-unanimous survey questions are shown for prospecting candidates to support, or, alternately, oppose, thus guaranteeing their popularity or lack thereof. To see what this politician's speeches might have looked like, we can look at FiveThirtyEight's "perfect stump speeches" that espouse only opinions held by a majority of Republicans or Democrats . The polls cited in this comic are all linked at http://xkcd.com/2305/sources . [A panel only with text. At the top there is three paragraphs of explanatory text. Below that is a paragraph in smaller gray font with link to sources. Below that there are two columns of poll results, each with a heading. There are six polls in the left and seven polls in the right column. Instead of a bulleted list, each poll has its percent that agrees given to the left of the statement, which is thus aligned to the right of this percentage. At the end of each statement there is a reference in brackets in gray font.] It's hard to get people to agree on anything in polls. But we agree about the coronavirus. Here's how Americans feel about COVID-19, along with other topics that get similar levels of agreement for comparison. Compiled with help from HuffPost polling editor Ariel Edwards-Levy. Sources: xkcd.com/2305/sources [Left column:] Recent coronavirus polls 86% say "stay-at-home orders are responsible government policies that are saving lives" rather than "an over-reaction" (ABC/Ipsos) 85% oppose reopening schools (NPR/Marist) 91% oppose resuming big sporting events (NPR/M.) 85% trust local health officials and health care workers (Axios/Ipsos) 93% are trying to maintain 6-foot distances while in public (Axios/Ipsos) 81% say Americans should continue to social distance for as long as is needed to stop the Coronavirus even if it means continued damage to the economy (Politico/Morning Consult) [Right column:] Other polls 81% enjoy apple pie (HuffPost/YouGov) 76% feel positively about kittens (HuffPost/YouGov) 84% have a favorable impression of Tom Hanks (Ipsos 2018) 89% say fair elections are important to democracy (Pew) 86% feel positively toward Betty White (Ipsos 2011) 86% do not trust Kim Jong-Un to do the right thing (Pew 2019) 64% are concerned about the emergence of "murder hornets" (YouGov)

Common Cold

Common Cold

https://www.xkcd.com/2306

https://www.explainxkcd.com/wiki/index.php/2306:_Common_Cold

[Three large viruses hang in the air in front of Cueball. The one closest to Cueball looks a bit like the virus causing the corona pandemic, although it is made clear it is not this type of virus. The other two are put together in small circles. The one behind the corona-like virus has 7 small circles, four in a group, one above and two below. The other has three circles. They are not so closely knit together, and may instead represent three smaller viruses rather than one large. The corona type virus addresses Cueball with a starburst above it indicating it speaks the lines above.] Corona-like virus: Hi there! We're the viruses that cause the common cold. Corona-like virus: This handwashing... Corona-like virus: It stops when this is all over, right? [Same setting in a slimmer panel.] Corona-like virus: It's just, it's making things really hard for us, too. Corona-like virus: Maybe we could make a deal? [Same setting in a frame-less panel. The large virus also speaks as indicated with a starburst above it.] Large virus: We won't kill you! Large virus: We just want to get back in your throat and make you feel gross now and then. Corona-like virus: Show us some mercy? [Zoom in on Cueball, beat panel.] [In the close-up of Cueball, he lifts his hand up, which has been balled into a fist. He is emphatic in his reply.] Cueball: No.

This comic is another in a series of comics related to the COVID-19 pandemic . This comic with talking viruses was followed by a comic debating if viruses are Alive Or Not ? Many of the measures humans have undertaken to fight SARS-CoV-2, such as careful hand-washing and sanitizing of frequently-touched surfaces, are effective against most pathogens. Hence, one of the ironic silver linings of the coronavirus pandemic is that the aggressive implementation of these measures is likely to slow the spread, not only of SARS-CoV-2 but of many common illnesses. If these measures become long-term social expectations, they may improve public health long after the current pandemic has passed. Hand-washing with soap is a particularly effective way to disable coronaviruses and influenza viruses, which have a viral envelope . Most common colds are caused by a rhinovirus , a non-encapsulated virus that is not as sensitive to soap. Nonetheless, proper and frequent hand-washing appears to reduce the spread of most viruses, by removing biological residue which harbors the virus. Hence, more aggressive hygiene is likely to have at least some impact on most easily transmissible diseases. In this strip, Randall addresses the matter from the point of view of viruses. Specifically, those that cause the common cold , imagining them as sentient entities, with spreading infection as their conscious goal. Much like in 2287: Pathogen Resistance , the humor comes from the perspective flip, where health measures intend to protect us are seen by the pathogens as terrifying attacks. In this strip, the cold viruses become aware that more aggressive hygiene measures are putting them at risk, and hope to negotiate with humanity, on the grounds that, unlike SARS-CoV-2, they are rarely fatal. Their hope seems to be that, once the current pandemic is brought under control, humanity will abandon these measures, and allow them to freely spread, once again. Cueball's adamant refusal likely reflects Randall's hope that this pandemic will result in lasting changes, slowing the spread of all diseases, including those which are merely very unpleasant, as opposed to actually fatal. By treating this as a conscious battle, people may be more inclined to be vigilant, and not allow the enemy any opportunity to recover. While colds are unlikely to kill otherwise healthy humans, they still cause symptoms that can be painful, even debilitating, in the short term. Previous strips made reference to the miserable nature of the disease. In December 2015, Randall released both 1612: Colds and 1618: Cold Medicine . The what if? book previously dealt with the plausibility of eliminating the common cold through aggressive physical distancing alone. The section in that book concluded that total elimination would be impractical. However, the current situation suggests that minimizing the spread of disease by careful hygiene measures is realistic. In the title text, Randall mentions a virus with the name metapneumovirus . He states that this is easily the common cold virus with the coolest name. But that does not mean it warrants our sympathy (as it is present in up to 40% of colds, and can be deadly in vulnerable populations). And he finishes by stating that "Colds suck. No mercy." So Randall would not be sorry to see the common cold eliminated, or at least substantially contained, by our coronavirus precautions. [Three large viruses hang in the air in front of Cueball. The one closest to Cueball looks a bit like the virus causing the corona pandemic, although it is made clear it is not this type of virus. The other two are put together in small circles. The one behind the corona-like virus has 7 small circles, four in a group, one above and two below. The other has three circles. They are not so closely knit together, and may instead represent three smaller viruses rather than one large. The corona type virus addresses Cueball with a starburst above it indicating it speaks the lines above.] Corona-like virus: Hi there! We're the viruses that cause the common cold. Corona-like virus: This handwashing... Corona-like virus: It stops when this is all over, right? [Same setting in a slimmer panel.] Corona-like virus: It's just, it's making things really hard for us, too. Corona-like virus: Maybe we could make a deal? [Same setting in a frame-less panel. The large virus also speaks as indicated with a starburst above it.] Large virus: We won't kill you! Large virus: We just want to get back in your throat and make you feel gross now and then. Corona-like virus: Show us some mercy? [Zoom in on Cueball, beat panel.] [In the close-up of Cueball, he lifts his hand up, which has been balled into a fist. He is emphatic in his reply.] Cueball: No.

Alive Or Not

Alive or Not

https://www.xkcd.com/2307

https://www.explainxkcd.com/wiki/index.php/2307:_Alive_Or_Not

[A chart consisting of vertical line, with 14 dots and a horizontal dashed dividing line drawn across the list a bit below the middle. Each dot has a label to the right of the line with a line pointing to the dot they belong to. Above and below the dividing line is a label with a broad arrow pointing up above and down below.] Up arrow: Alive Down arrow: Not alive [Dot labels from top to bottom above the dashed line:] Animals (Normal) Animals (Weird ones like jellyfish and coral) Fungi Plants Slime molds Bacteria Archea Viruses [Dot labels from top to bottom below the dashed line:] Prions Fire Clouds Fossils Rocks shaped like faces Regular rocks

There is no universally-accepted definition of " life "; all definitions thus far proposed have either excluded some things commonly understood to be alive or included some things commonly understood to not be alive. Take reproduction, a trait commonly assumed to be essential and unique to life; by this definition, anything which cannot reproduce (including mules , worker bees , and postmenopausal women) would be considered nonliving, while anything which can duplicate itself (including computer viruses , advanced 3D printers , and fire —see below) would be considered alive. Many more elaborate definitions of life have been attempted over the decades. Some common additional factors include: Despite all of this, the only definite definition of "life" is "something everyone agrees is alive". This comic attempts to rank several types of things by how likely people are to perceive them as "alive". As there is a debate as to whether viruses are alive or not, Randall has taken a side, and may spark debate, by putting viruses above the alive line. Given that this comic was released during the early days of the COVID-19 pandemic, viruses are for sure on Randall's mind, given that most comics more than a month before this one was about COVID-19. And this comic is most likely inspired by this, and the previous comic 2306: Common Cold , where the cold viruses are definitely alive, and afraid. Interestingly, the vertical line linking the categories extends beyond both the most-alive and least-alive things, making one wonder what Randall might think is more alive than "normal animals" or less alive than "regular rocks". In the latter direction an explanation might be that shortly before this comic the scientific press wrote about heat-resistant bacteria that live in the desert and slowly eat regular rocks generating their own water in this process making even the sand in the desert partially alive. [A chart consisting of vertical line, with 14 dots and a horizontal dashed dividing line drawn across the list a bit below the middle. Each dot has a label to the right of the line with a line pointing to the dot they belong to. Above and below the dividing line is a label with a broad arrow pointing up above and down below.] Up arrow: Alive Down arrow: Not alive [Dot labels from top to bottom above the dashed line:] Animals (Normal) Animals (Weird ones like jellyfish and coral) Fungi Plants Slime molds Bacteria Archea Viruses [Dot labels from top to bottom below the dashed line:] Prions Fire Clouds Fossils Rocks shaped like faces Regular rocks

Mount St. Helens

Mount St. Helens

https://www.xkcd.com/2308

https://www.explainxkcd.com/wiki/index.php/2308:_Mount_St._Helens

[Caption above graph:] Heights of mountains in Washington State Over time [A graph is shown with close to 30 horizontal gray lines which seem not to change much, if any, as they go from left to right. Only the top 6 gray lines are distinctly separated from others. The top line is way above the second line which again is far above the next two that are close together. Two more close together is somewhat further down, and just below them the rest of the lines follow in close proximity down to the bottom of the graph. A single black line is also shown. It begins as the fifth highest line, just above the two last mentioned above. It, like all other lines, goes horizontally, but only three fifths of the way across the graph – then it immediately drops down well below most of the other lines (at 1980) and levels off, continuing on its horizontal path. There is a caption above the graph, and both Y-axis and X-axis has labels. For the Y-axis there is a tick for every label, for the X-axis only every 2nd tick has a label. A unit is given on the top label on the Y-axis.] [X-axis:] 1920 1940 1960 1980 2000 2020 [Y-axis:] 15,000 feet 14,000 13,000 12,000 11,000 10,000 9,000 8,000

This comic marks the 40 year anniversary of the May 18, 1980 eruption of Mount St. Helens that killed 57 people. It was a Monday so a normal release day could be used to mark this event. It shows a graph of the height of the mountains in the state of Washington as a function of time over the last 100 years. The only mountain to change its height significantly over this time period is Mount St. Helens , which the comic is named after. It is also the only black line as all other (30?) lines are gray. Mount St. Helens is a volcano that famously and explosively erupted in 1980. Millions of tons of earth were blasted from one face of the mountain all over the surrounding countryside. After it was over, the peak of Mount St. Helens was no longer the 5th highest in the state of Washington , having lost approximately 1,300 feet (400 m) in height (from 9,677 ft (2,950 m) pre-explosion to 8,363 ft (2,549 m) post-explosion). The comic shows a rare event that had major effect and was predictable in hindsight, but would have surprised an observer that is just tracking the height of Mt. St. Helens in a non-representative timeframe. Such an event is called a Gray Rhino event. Currently, the 5 highest mountain peaks in Washington State are Mount Rainier (at 14,411 ft or 4,392 m), Mount Adams , Mount Baker , Glacier Peak , and Bonanza Peak . As shown in the comic, Mount St. Helens was the 5th highest, but now has fallen to #35 (using a topographic prominence cut-off of 500 m (1640 feet)). Only mountains above 8,000 feet (2,438 m) are included, with the graph topping at 15,000 feet (4,572 m), 600 feet (182 m) above the highest mountain. There are 92 peaks above 8000 feet in the state, so not all are included and the lines are not really distinct below 9000 feet. Seems like there are less than 30 lines drawn. Of course it says Mountains not Mountain peaks, but there are only four mountain ranges in Washington with peaks above 8000, so he must mean peaks! Technically, the other mountains may be fluctuating in height as well, due to erosion or the movement of Earth's tectonic plates, but this phenomenon should not be visible on the time-scale and vertical resolution that Randall has plotted. Precision GPS measurements of various peaks in Washington have only been available since 2010, and it's likely that the primarily volcanic mountains of Washington experience significant but comparatively slight variations throughout the year due to snowfall, melt, or the pressure of swelling magma inside volcanic cores. These changes go largely unmeasured, while the mountains continue to appear equally physically unchanging and imposing both in person and from a distance. Source: Seattle Times . So while the comic does appear to show some slight fluctuations in height for mountains, that is more likely a side-effect of the comic's free-hand drawing style than an accurate reflection of any real fluctuations. The title text is a play on the term "peak" meaning both the highest point of a mountain and also the optimal, most famous or most impressive stage of a trend; for instance: "The band Rolling Stones really peaked in the 80s." [Caption above graph:] Heights of mountains in Washington State Over time [A graph is shown with close to 30 horizontal gray lines which seem not to change much, if any, as they go from left to right. Only the top 6 gray lines are distinctly separated from others. The top line is way above the second line which again is far above the next two that are close together. Two more close together is somewhat further down, and just below them the rest of the lines follow in close proximity down to the bottom of the graph. A single black line is also shown. It begins as the fifth highest line, just above the two last mentioned above. It, like all other lines, goes horizontally, but only three fifths of the way across the graph – then it immediately drops down well below most of the other lines (at 1980) and levels off, continuing on its horizontal path. There is a caption above the graph, and both Y-axis and X-axis has labels. For the Y-axis there is a tick for every label, for the X-axis only every 2nd tick has a label. A unit is given on the top label on the Y-axis.] [X-axis:] 1920 1940 1960 1980 2000 2020 [Y-axis:] 15,000 feet 14,000 13,000 12,000 11,000 10,000 9,000 8,000

X

X

https://www.xkcd.com/2309

https://www.explainxkcd.com/wiki/index.php/2309:_X

[Cueball holds a laptop with code visible on the screen.] Cueball: I've developed a new programming language! Offpanel voice: Didn't a judge order you to stop doing that? [In a frameless panel, Cueball holds the laptop with one hand and types on the keyboard.] Cueball: Higher court threw out the ruling! Cueball: I'm back, suckers! Offpanel voice: Dammit. [Cueball holds the folded down laptop at his side.] Cueball: But I promise it's good this time! Cueball: Just normal code. Good clean syntax. Nothing weird. Offpanel voice: Okay... [Cueball holds the laptop at his side, and raises a finger on his other hand.] Cueball: Except the only variable name is "X". To refer to different variables you have to write "X" in different fonts. Offpanel voice: I'm calling the court. Another offpanel voice: Maybe we can appeal.

Cueball has developed a new programming language with novel syntax. Such languages are usually classified as esoteric languages — programming languages developed for no practical use other than novelty, challenge, or academic interest, and which are difficult to understand or work with (although that doesn't stop people from trying to use them). Some classic examples of these are INTERCAL and brainfuck . Normally, there is no law against developing bad programming languages or bad code (although some would argue there should be). The law often has to play catch-up with technology. However, as when the EPA took an interest in Cueball's Laptop Issues , and Cueball's other tech support problems , it seems that a judge has previously ordered Cueball to stop developing new programming languages, possibly because the result was so egregious as to cause real harm. However, the ruling was overturned on appeal, and Cueball is free to inflict his work on the world once again, unless and until there is another appeal. Cueball's use of the phrase " higher court" suggests that he has not gotten a ruling from the Supreme Court of the United States or whatever state has jurisdiction over him, or else he would have said so, and evidently the offscreen voices hope to appeal to them and get Cueball's injunction reinstated. A variable is a piece of data (such as an integer or a string of text) whose value can change over the run of a program. Variables are identified by name and can usually be named any string of alphanumeric characters. To make code easier for a human to follow, variables are usually given a name that indicates what the variable is for; for example, a variable counting how many seconds have passed since the program was launched might be called elapsedTime . The overall concept of a variable is usually first taught in Algebra , where the most basic nondescript name for a variable is x . When first learning or teaching programming, it's not unheard of for sample variables in practice problems to be named "x". However, outside of a controlled learning environment calling any variable "x" is considered bad coding practice, because anyone reading the code will not immediately understand what the variable does unless they are familiar with it. Even the original programmer may come back to it and find that they have forgotten what the variable was for. Here, Cueball is developing a language where all variables are named X - and the only way to differentiate different Xs is to write it in different typefaces. Needless to say, this is a terrible idea. The language would be a nightmare to program in, as all of the variables would look very similar unless careful attention is being paid, and there would be little to no way to determine what each one does, since font names are typically not very descriptive. Additionally, the fact that some fonts look similar (such as Arial and Helvetica) would require the programmer to have an intricate knowledge of different fonts and how to distinguish them from only one letter. Such a language would also require the source code files to be in some rich text format such as a Word document, in order to store the font information. Additionally, it would also require the use of a word processor or similar in order to edit the code. Programs would also run into difficulties if the system does not have the required fonts installed, or if the font is not licensed for them to use. By contrast, normal code is always written in plain text (usually with ASCII or UTF-8 encoding), which does not specify a typeface and can be edited by even the most basic of text editors. This comic may also be a jab at mathematicians, who by convention use variable names which are short and nondescript (e.g. "x"), and which can also be "typeface sensitive" - for example, ℕ denotes the set of natural numbers, and it is not uncommon to see the definition of a limit as "For every ℇ>0 there exists N in ℕ such that for every n in ℕ, if n>N, |f(n)-l|<ℇ". Or for example, ℜ may denote the real part of a complex number, whereas ℝ denotes the set of real numbers, and R might denote the radius of some circle in the complex plane. The title text references the fact that most code editors use a monospaced font (i.e., one where every character is the same width), as opposed to variable-width fonts, in which some characters like 'I' are narrower than others. This is partly because fixed horizontal alignment is sometimes useful when dealing with certain text strings. 'Variable-width variables', a pun on two meanings of the word 'variable', refers to the fact that the letter X, like all letters, has different widths in different fonts. This would make this fixed alignment almost impossible, thus creating yet another reason why Cueball's language would be highly unpleasant to use. It likely also directly (mis)refers to systems such as variable-width encoding in which the data linked to in a variable storage is packed into an unfixed number of bits and/or bytes. Such systems often use Huffman-type encoding to progressively differentiate, from the initial elements, how many more elements are needed to fully define the value, but a reserved deliminating value marking the end of a cumulative arbitrary-length array might be considered another form. [Cueball holds a laptop with code visible on the screen.] Cueball: I've developed a new programming language! Offpanel voice: Didn't a judge order you to stop doing that? [In a frameless panel, Cueball holds the laptop with one hand and types on the keyboard.] Cueball: Higher court threw out the ruling! Cueball: I'm back, suckers! Offpanel voice: Dammit. [Cueball holds the folded down laptop at his side.] Cueball: But I promise it's good this time! Cueball: Just normal code. Good clean syntax. Nothing weird. Offpanel voice: Okay... [Cueball holds the laptop at his side, and raises a finger on his other hand.] Cueball: Except the only variable name is "X". To refer to different variables you have to write "X" in different fonts. Offpanel voice: I'm calling the court. Another offpanel voice: Maybe we can appeal.

Great Attractor

Great Attractor

https://www.xkcd.com/2310

https://www.explainxkcd.com/wiki/index.php/2310:_Great_Attractor

[Cueball and Beret Guy stand next to each other, talking. Beret Guy leans towards Cueball by bending down one knee.] Cueball: I can't believe it's still light out. It's 8:00 PM! Beret Guy: Seriously! This morning I fell off the wall. [In a frame-less panel with the same setting Beret Guy is looking and pointing to the right.] Cueball: Wait, why were you sleeping on the wall? Beret Guy: The Great Attractor is near the horizon at night right now. [Zoom in on Beret Guy, who hold one hand palm up towards Cueball who is speaking to him off-panel.] Cueball (off-panel): The Great Attractor? Beret Guy: Yeah! The space one. Beret Guy: It pulls on me extra hard. Doctors said it's something to do with galactic motion and how many dimensions my bones have. [Cueball is still standing as Beret Guy slides away to the right, while looking and leaning back towards Cueball. He holds his arms slightly out, to keep his balance. Lines behind him and at his feet indicates his motion, even if he is clearly not walking. In his last word the letters becomes italic after Good and the last three Ts becomes smaller and smaller than the previous letters.] Beret Guy: This time of year, it's below us all day, so I stand vertically. But day-sliding season is near! Beret Guy: Let me know if you have any errands to run to the south! Beret Guy: Good niiight t t

Cueball comments on the fact that as summer approaches, the sun rises earlier and sets later, a common topic of conversation, especially to complain that it is still light at times of day where you are used to it being dark out. Beret Guy comments that he fell off of the wall this morning, a seemingly unconnected topic. People will often complain about falling out of bed as an indicator of having slept badly. The later sunset is often linked to worsened sleep . However, Beret Guy didn't fall from the bed, he fell from the wall. While being able to figure out he's talking about his worsened sleep, Cueball is understandably confused, so Beret Guy clarifies. Beret Guy is strongly affected by the Great Attractor , a large gravitational anomaly that influences the galaxies near it, but is difficult to observe directly. Beret Guy claims that the Great Attractor pulls on him unusually hard, which could be another one of his strange powers . This attraction, while not overpowering the gravity of the Earth, (he states in the title text that he can "Jump extra high" when it is above him) affects his life greatly. For Beret Guy his attraction to the Great Attractor means that, at various times, like now, he can lie on the vertical surface of any wall (external or internal) that is currently oriented in a fortuitous direction (i.e. facing north). He fell off the wall this morning due the Great Attractor being below him during daylight hours and on the horizon during night hours. Thus, Beret Guy's complaint in the first panel comes across as an attempted solidarity with Cueball's complaint; he was still asleep when the Great Attractor moved to below him, causing him to fall off the wall and presumably awaken him. The Great Attractor reaches the same apparent location once in a stellar day which is about four minutes shorter than the solar day. This means Beret Guy would only be able to sleep on walls for certain part of the year, as the time of day when the Great Attractor is near the horizon would occur 4 minutes earlier each day. He gives a short explanation of which Attractor he refers to (the space one) and why the Great Attractor affects him. According to his doctors it is apparently caused by the motion of galaxies and how many dimensions his bones have. Since having fewer than 3 spatial dimensions may lead to trouble, his bones may be existing in more dimensions than our normal 3 dimensions of space and 1 of time. Galactic motions normally have no significant effect on a person with 3-D bones. [ citation needed ] Beret Guy then says that day-sliding season is near, due to the Great Attractor being at the horizon in the day, and offers to run errands for Cueball in the South, implying that he will be pulled towards the south during day-sliding season, and can run much faster in that direction. Beret Guy is not standing straight up during this comic, he has one knee slightly bent towards Cueball in the first two panels. This is because it is evening (8:00 PM as Cueball states) and the Great Attractor is now coming near the horizon, where it will be during the night. So Beret Guy will be pulled towards the south, behind him in the comic, and thus leans away from the pull. In the final panel, when he leaves Cueball, moving right towards south and into the pull, he can be seen sliding along the ground without walking. He leans a bit back to not stumble forward. His last sentence also indicates that he either speeds up or that he is a little uncertain on his feet altering his voice. He mentions that at the moment during day-time the Great Attractor is beneath him so he can stand straight. He then just feels a little heavier (he will thus weigh more than another person with the same mass). In the title text he says he liked living in the south because the Great Attractor was often above him, meaning he could jump higher with the help of its pull (and would weigh less than a normal person with same mass). Since he could jump, the force is clearly weaker than Earth's gravity, but still enough for him to easily slide over the ground when it is near the horizon. So he could likely win some high-jump or long-jump competitions if he chose the right time and place. Being Beret Guy, he is never really unhappy, so he states that he also likes it here (in the north). But then he continues to comment on how easy it will be for him to get to the south. Because if he entirely stopped bracing himself against the pull by crouching into a more spherical shape, and just waited for the Great Attractor to get near the horizon again, then the pull would cause him to start rolling over the ground to some place with lower net gravitational potential, i.e. further south, where the Great Attractor will be more directly over his head. In practice travelling any extended distance, let alone thousands of kilometers, by rolling would likely result in unpleasant bruising and be generally a bad idea. [ citation needed ] A prior example of an xkcd character with alternate gravitational susceptibility is 417: The Man Who Fell Sideways , where a consistent off-vertical pull somehow applies (rather than one linked to a spot on the stellar sphere). In 1376: Jump Cueball floats sideways across the ground a bit above Earth, in a similar idea to being pulled sideways. See also these other fictional examples of 'personalized' gravitational susceptibilities . Beret Guy has previously been interested in strange attracting forces in the universe, in 502: Dark Flow , where he hoped it was his mom and wished she would pull on him. It was though not about the Great Attractor, and the force did not clearly affect him, although his love for his mom did affect two space probes, as mentioned in the title text. This comic came out just a bit more than a month before the next comic with one of Beret Guy's strange powers, 2325: Endorheic Basin . Which is interesting since the previous comic with such a power came back in November 2017, 1922: Interferometry , more than 2.5 years before this one. Also in the Endorheic Basin comic strange forces exerted a pull on Beret Guy, although in that it was he who attracted water, where here it was himself that was most affected. Some of the humor of the comic has to do with the immense differences in scale between Beret Guy and the Great Attractor. In very round numbers our own Milky Way galaxy is 150,000 - 200,000 light years across. It is just one of several galaxies in something called the Local Group , which is around 10,000,000 light years across. And the Local Group is itself in something called the Local Supercluster (also called the Virgo Supercluster), around 110,000,000 light years across. Each galaxy, each group, and each supercluster is not just a chance alignment, but is a gravitational coherent structure. And all this is just yet a part of the even larger Laniakea Supercluster in which also the Great Attractor is located, along with more than 100,000 other galaxies, in a region of space spanning more than 500 million light years. Something unpredictable (hence "anomalous") is going on with the galaxies in the Local Supercluster (including our own). These galaxies are indeed accelerating away from one another as seen by their red shift. Hubble's Law predicts the expansion should be uniformly proportional to their distance from Earth and from one another. But for the Local Supercluster something is restricting the expansion. That something is, as "viewed" from Earth, somewhere in the direction of the Southern Triangle constellation but 250,000,000 light years distant, and has (but only since 1988) been termed the Great Attractor. The Great Attractor can't conveniently be seen at visible wavelengths, because that direction is the so-called Zone of Avoidance : the area of the night sky obscured by our own Milky Way. Boiling this all down: something a quarter of a billion light years away that makes an anomalous blip in the local rate of expansion of the universe, and whose existence astronomers deduce only by X-ray observations of stellar red-shift, has large-scale effects on everyday gravitational forces uniquely experienced by Beret Guy. OK, now you can smile. [Cueball and Beret Guy stand next to each other, talking. Beret Guy leans towards Cueball by bending down one knee.] Cueball: I can't believe it's still light out. It's 8:00 PM! Beret Guy: Seriously! This morning I fell off the wall. [In a frame-less panel with the same setting Beret Guy is looking and pointing to the right.] Cueball: Wait, why were you sleeping on the wall? Beret Guy: The Great Attractor is near the horizon at night right now. [Zoom in on Beret Guy, who hold one hand palm up towards Cueball who is speaking to him off-panel.] Cueball (off-panel): The Great Attractor? Beret Guy: Yeah! The space one. Beret Guy: It pulls on me extra hard. Doctors said it's something to do with galactic motion and how many dimensions my bones have. [Cueball is still standing as Beret Guy slides away to the right, while looking and leaning back towards Cueball. He holds his arms slightly out, to keep his balance. Lines behind him and at his feet indicates his motion, even if he is clearly not walking. In his last word the letters becomes italic after Good and the last three Ts becomes smaller and smaller than the previous letters.] Beret Guy: This time of year, it's below us all day, so I stand vertically. But day-sliding season is near! Beret Guy: Let me know if you have any errands to run to the south! Beret Guy: Good niiight t t

Confidence Interval

Confidence Interval

https://www.xkcd.com/2311

https://www.explainxkcd.com/wiki/index.php/2311:_Confidence_Interval

[A graph is shown in the middle of the panel. There is a square frame around it. The graph has two unlabeled axes with ticks along both axes. The axes end in arrows. A solid line graph is shown. It begins around the middle of the Y axis, goes up and flattens twice before falling down towards the right. Far above and just below the frame around the graph are two gray dotted lines. They do not follow the same path as the solid line inside the frame, but do follow the same general trend. Below the graph, but inside the frame, is a caption:] Fig. 2: Predicted Curve [Caption below the panel:] Science tip: If your model is bad enough, the confidence intervals will fall outside the printable area.

This is another one of Randall's Tips , this time a Science Tip . This is the second time that a category of tips (with the first being " Protip ") has been re-used. Graphs of continuous functions' predicted values often show confidence intervals , a region (either shaded or marked with dotted lines, the latter used here) that indicates the margin of error for the prediction at any point. The joke in this comic is that the estimate has so much uncertainty that the confidence interval extends off the top and bottom of the chart, which in a real report would usually prevent it from being printed and require a re-scaled chart to show it (if not declined altogether, as data with such wide variance might be deemed useless). This may be a tip as if it's outside the printable area, it won't be seen by anyone who reads it, and thus they won't realize how bad your model is, though this is more of a tip in how to trick people into falsely thinking you've shown a good result with your work than it is a tip in presenting an actual legitimate useful scientific result. In the title text, a millisigma would be an error of +/- 1/1000th of a standard deviation . Statistical error and uncertainty is typically measured by standard deviation , which is written in formulas with the Greek letter sigma , and is also frequently referred to by the word "sigma." Measurements of sample means, one of the most common experimentally determined variables, will tend to follow a normal distribution , such that 68 percent of members of the population will fall within one sigma (plus or minus) of the mean value, 95 percent within two sigma, and 99.7 percent within three sigma. Any of these intervals may be usefully reported as the confidence interval, so long as it's made clear to the reader, but two- or three-sigma are sufficient for most applications. However, this graph shows data of such poor quality (or such poorly-chosen y -axis bounds) that even the millisigma confidence interval (0.08% of the population -- not often used in science, but occasionally found in e.g. molecular analysis tools ) does not fit on the graph. Variations in the curve that are small compared to the error bar typically can't be distinguished from errors. Therefore, the shape of the curve - and the entire graph in this example - is meaningless. [A graph is shown in the middle of the panel. There is a square frame around it. The graph has two unlabeled axes with ticks along both axes. The axes end in arrows. A solid line graph is shown. It begins around the middle of the Y axis, goes up and flattens twice before falling down towards the right. Far above and just below the frame around the graph are two gray dotted lines. They do not follow the same path as the solid line inside the frame, but do follow the same general trend. Below the graph, but inside the frame, is a caption:] Fig. 2: Predicted Curve [Caption below the panel:] Science tip: If your model is bad enough, the confidence intervals will fall outside the printable area.

mbmbam

MBMBaM

https://www.xkcd.com/2312

https://www.explainxkcd.com/wiki/index.php/2312:_mbmbam

[Cueball, Megan, and White Hat are standing next to each other, talking. Megan has her hands raised to the side, in a shrugging gesture.] Megan: Odd how in physics " mb " is both millibars (pressure) and millibar n s (area). Megan: mbmb could mean millibar-millibarn, which is a unit of force, strangely. White Hat: Units are weird. [Same scene - Megan is now checking her phone. White Hat is raising his right index finger.] Cueball: So what's mbmbam , the My-Brother-My-Brother-And Me unit? Megan: Millibar-milliibarn-attometer, I guess? That'd be a unit of energy. 10 -47 Joules. White Hat: "One podcast" [Same scene in a frameless panel. Megan holds her phone to her side. White Hat has his arms raised to the side, excited.] Cueball: 10 -47 sounds small. Megan: Yeah, it's roughly the energy you'd need to lift one yeast cell by one Planck length in Earth's gravity. White Hat: Planck yeast! [Same scene in a regular panel. Megan has put away her phone, and has her right index finger raised. White Hat has his hands balled into fists, frustrated.] Cueball: Doesn't Planck yeast rise on its own? Megan: Yeah, that's what makes quantum foam. But data suggests our universe is flat. Megan: String theory says it's because spacetime has unleavened dimensions. White Hat: ...I hate you.

In part, this comic is an homage to the referenced podcast, My Brother, My Brother, and Me , which often features rapid garden-path conversations and puns and double entendres that are at once groan-worthy and delightfully witty. "MBMBAM" is an acryonym of " M y B rother, M y B rother, A nd M e". The millibar is a metric unit of pressure (force per unit area), equal to a thousandth of a bar , or 100 Pa . It is slightly less than one-thousandth of sea-level atmospheric pressure on Earth (a standard atmosphere is 1013.25 millibar). The millibarn is a metric unit of area, equal to a thousandth of a barn (a humorously-named unit approximately equal to the cross-sectional area of a uranium nucleus), or 10^-31 m^2 or 10^-27 cm^2. Both units would theoretically have the symbol mb . Hence mbmb (the pressure unit multiplied by the area unit) would be a unit of force. This can be seen by applying dimensional analysis; pressure x area = (force/area) x area = force. Nobody in the comic strip discusses the magnitude of this force, but it would be 100 Pa x 10^-31 m^2 = 10^-29 newtons = 10^-24 dynes, or about the weight of an electron under Earth's gravity. am would be the symbol of an attometer , or 10^-18 meters. Multiply that to create the unit mbmbam , which would be a unit of energy. Specifically, it would be a unit of work: the energy expended to move an object. More dimensional analysis: force x distance = (work/distance) x distance = work. The actual value of 1 mbmbam is correctly calculated in the comic: 100 Pa x 10^-31 m^2 x 10^-18 m = 10^-47 joules = 10^-40 erg. White Hat dubs this unit "one podcast". The final panel is an extended series of puns: 'rise' referring to physically moving upward as well as biologically growing (expanding and becoming lighter and softer) as yeasts do; 'foam' referring to both quantum foam (the fluctuation of spacetime on very small scales due to quantum mechanics) as well as the foam generated by yeast fermenting; 'unleavened dimensions' punning on the eleven dimensions of spacetime in string theory (actually, ten— M theory says eleven), while continuing to play on the theme of yeast--in this case, the universe is presumably flat because some of its dimensions lack the Planck yeast that would make them rise. The example used in the comic of lifting a yeast cell 1 Planck length is one of many possible examples of 1 mbmbam of work. (The Planck length , approximately 1.6×10^−35 m or 1.6×10^−33 cm, is how far light travels in one unit of Planck time .) Another interpretation of 1 mbmbam would be the work necessary to pull two socially distancing (6 ft) SARS-CoV-2 virions apart by the thickness of a single strand of hair against the gravity they exert on each other. The Planck Era (or Planck Epoch ) referenced in the title text is the near infinitesimally short period covering the first 10^-43 s after the Big Bang, when energies were so high that the four fundamental forces were combined into one and ordinary subatomic particles didn't yet exist. It is unlikely there were advice shows during this era [ citation needed ] , so this would likely be a modern nostalgia show for physicists. The title text is also a play on My Brother, My Brother and Me's tagline: An advice show for the modren [sic] era. [Cueball, Megan, and White Hat are standing next to each other, talking. Megan has her hands raised to the side, in a shrugging gesture.] Megan: Odd how in physics " mb " is both millibars (pressure) and millibar n s (area). Megan: mbmb could mean millibar-millibarn, which is a unit of force, strangely. White Hat: Units are weird. [Same scene - Megan is now checking her phone. White Hat is raising his right index finger.] Cueball: So what's mbmbam , the My-Brother-My-Brother-And Me unit? Megan: Millibar-milliibarn-attometer, I guess? That'd be a unit of energy. 10 -47 Joules. White Hat: "One podcast" [Same scene in a frameless panel. Megan holds her phone to her side. White Hat has his arms raised to the side, excited.] Cueball: 10 -47 sounds small. Megan: Yeah, it's roughly the energy you'd need to lift one yeast cell by one Planck length in Earth's gravity. White Hat: Planck yeast! [Same scene in a regular panel. Megan has put away her phone, and has her right index finger raised. White Hat has his hands balled into fists, frustrated.] Cueball: Doesn't Planck yeast rise on its own? Megan: Yeah, that's what makes quantum foam. But data suggests our universe is flat. Megan: String theory says it's because spacetime has unleavened dimensions. White Hat: ...I hate you.

Wrong Times Table

Wrong Times Table

https://www.xkcd.com/2313

https://www.explainxkcd.com/wiki/index.php/2313:_Wrong_Times_Table

[Caption above table:] Wrong Times Table The incorrect answers that feel most right to me

A "times table" (or multiplication table ) is a table used to show the products of numbers. Typically, elementary school children are taught to memorize the table of whole numbers up to 10 as part of learning arithmetic. In this comic Randall supplies his own alternative version of the multiplication table, with entirely incorrect values that nonetheless "feel" reasonably correct to him. It is unclear how his values are derived, as they don't follow a consistent pattern, but it could be that when calculating products, he sometimes has to correct his mental arithmetic, perhaps thinking along such lines as "8*4 is 36... Or, wait, is it 32?". Most of the values are transposed from their correct position (e.g., adding or subtracting one -- or two, or three -- from one or both multiplicands), some are "off by one" (or two, or by a factor of two), and some (mostly in the 1 row and column) could be created by adding, subtracting, or dividing the two factors instead of multiplying them. It is notable that some properties of mathematics are not followed, as sometimes smaller multiplicands multiply to a larger product than larger multiplicands, and sometimes two even multiplicands produce an odd product. The table is symmetric, indicating that Randall's form of multiplication is commutative . The title text (referencing Randall's suspicion that 6x7=42 may be wrong) is an allusion to The Hitchhiker's Guide to the Galaxy , in which the ultimate answer to life, the universe, and everything is said to be forty-two . However, in the book this answer is meaningless without knowing the ultimate question , and so to calculate the ultimate question, a planet-sized computer is constructed. This later becomes Earth, but Earth is destroyed shortly before its calculation is complete. Arthur Dent, one of the last surviving humans, has some white mice (pan-dimensional beings looking like white mice to us) try to get him to give them his brain, so they could attempt to recreate the ultimate question, hoping it may be stored within his brain since he was part of the computer matrix up to just before Earth was destroyed a few days before completing a 10 million year calculation. Arthur refuses, and the mice try to think of some question that makes the answer 42 make sense, like " how many roads must a man walk down ". They also suggest 6x7. Arthur later tries to recreate the question himself by picking letter tiles from a bag, and produces the sentence "What do you get if you multiply six by nine". This leads him to remark "I always thought something was fundamentally wrong with the universe." Note, however, that operation of said planet-sized computer was disrupted, both by its near-total destruction and by the much earlier crash-landing onto it of the 'B' Ark and its somewhat useless passengers, so it's also possible the universe is okay and only the question was computed incorrectly. As it happens, 6x9 = 42 in base 13, but Douglas Adams has disclaimed this as being a mere coincidence. In Randall's table, neither 6x7 nor 6x9 are said to result in 42, but 7x7 is. If we consider the smaller multiplicand to be a and the larger to be b , then (one of infinitely many possibilities of) the formulas used by Randall are as follows: The correct multiplication table for the numbers 1-10 is below: [Caption above table:] Wrong Times Table The incorrect answers that feel most right to me

Carcinization

Carcinization

https://www.xkcd.com/2314

https://www.explainxkcd.com/wiki/index.php/2314:_Carcinization

[Cueball and Megan are walking next to each other towards the left with Megan looking back at Cueball.] Megan: Have you heard of "carcinization"? Megan: The tendency of nature to evolve things into crabs. Cueball: Oh? [They continue to walk, both of them looking forward.] Megan: Yeah, the basic "crab" design has evolved separately a number of times. Cueball: Evolution just loves making crabs, I guess! [Narrower panel with only Megan seen walking on while lifting both her arms slightly to each side.] Megan: Apparently! [Two smaller beat panels are drawn between the previous and next normal sized panels. The first is a bit lower than the top of the normal panels, and is partly lying in over the other small panel, which is below and to the right of the first. The top panel shows Megan continuing to walk along. The second shows Megan stopping and turning to look back.] [Megan has turned completely and is looking down at a small crab scuttling along on the ground where Cueball was before.] Megan: Oh no In January 2020, less than half a year before this comic was released, the Dinosaur Comic also released a comic about Carcinization . This web comic is on Randall's list of Comics I enjoy and was also used in 145: Parody Week: Dinosaur Comics . Another popular webcomic, Questionable Content, had a crab-themed comic the day before this comic was released. Just a month after the release of this comic, "carcinization" was the Word of the Day in Wiktionary. This comic was also the inspiration for SCP-6010 , a story about all animal life turning into crabs, set in the SCP Foundation setting. SCP 6010 mentions life turning into crabs o June 1st 2019, the release date for this comic.

As Megan is telling Cueball , separate species of animals have evolved into "crab-like" forms at different times. Naturalists who noticed the tendency gave it the name carcinization . It is a specific form of convergent evolution , where differing families of animals (in this case, nominally across the crustacea ) develop a tendency towards developing a 'crab' bodyplan to a greater degree than their origins would suggest. A similar process has created several varieties of river dolphin with similar adaptations to their environments, despite being 'stranded' offshoots of different forerunner pelagic species. "True crabs" ( Brachyura ) form just a small subset of the Crustacea subphylum, and the Cancer genus is a subset of that, yet there appears to be something about the bodyplan and even resulting behaviour that has meant a number of species have arisen from alternate areas of the family tree that are now trivially indistinguishable without extensive study. Carl Linnaeus even initially included all Crustacea under the 'Cancer' genus (using the Latin name for crabs), and his taxonomic classification has been heavily refined as further knowledge has come to light, in order to reveal this phenomenon. Apparently this principle is much stronger in the webcomic than in real life, as shortly after being told this, Megan notices that Cueball (not a crustacean!) has himself turned into a crab. This isn't really evolution as we know it (outside Pokémon evolution at least), which refers to changes (usually gradual changes, but not always) in a species across generations caused by random mutations. The organisms individually never change [ citation needed ] , they are merely different from their ancestors, and the organisms with changes that make them more fit for their environment are the ones who are more likely to survive long enough to pass down those changes. What happens to Cueball is more like a transformation, but it could still be called 'carcinization', since he becomes crab-like. The comic strip might be an allusion to Franz Kafka's short story The Metamorphosis (another word used to describe life-forms that dramatically transform themselves, like caterpillars turning into butterflies), which starts with the main character suddenly waking up and finding that he has transformed into a giant bug. Cueball's sudden transformation is perhaps explained by the title text, that "Nature abhors a vacuum and anything that's not a crab". The text is a reference to Aristotle's Horror vacui , a statement about how empty space tends to be immediately refilled by surrounding things, so vacuums seem to be impossible to maintain. As does "not being a crab", it seems. Strictly speaking, we don't know for certain that Cueball actually transformed; it could be that he has ducked out of sight and left a crab in his place (or noticed a crab conveniently nearby) to play a prank on Megan. [Cueball and Megan are walking next to each other towards the left with Megan looking back at Cueball.] Megan: Have you heard of "carcinization"? Megan: The tendency of nature to evolve things into crabs. Cueball: Oh? [They continue to walk, both of them looking forward.] Megan: Yeah, the basic "crab" design has evolved separately a number of times. Cueball: Evolution just loves making crabs, I guess! [Narrower panel with only Megan seen walking on while lifting both her arms slightly to each side.] Megan: Apparently! [Two smaller beat panels are drawn between the previous and next normal sized panels. The first is a bit lower than the top of the normal panels, and is partly lying in over the other small panel, which is below and to the right of the first. The top panel shows Megan continuing to walk along. The second shows Megan stopping and turning to look back.] [Megan has turned completely and is looking down at a small crab scuttling along on the ground where Cueball was before.] Megan: Oh no In January 2020, less than half a year before this comic was released, the Dinosaur Comic also released a comic about Carcinization . This web comic is on Randall's list of Comics I enjoy and was also used in 145: Parody Week: Dinosaur Comics . Another popular webcomic, Questionable Content, had a crab-themed comic the day before this comic was released. Just a month after the release of this comic, "carcinization" was the Word of the Day in Wiktionary. This comic was also the inspiration for SCP-6010 , a story about all animal life turning into crabs, set in the SCP Foundation setting. SCP 6010 mentions life turning into crabs o June 1st 2019, the release date for this comic.

Eventual Consistency

Eventual Consistency

https://www.xkcd.com/2315

https://www.explainxkcd.com/wiki/index.php/2315:_Eventual_Consistency

[Cueball sits at a home desk.] Laptop: I know it's hard to focus right now, but we should try to finish testing the DB. Cueball: Ughhhh. Cueball: Okay. [A frameless panel. Cueball still sitting at his desk. He has his hand on his chin.] Laptop: The system needs to guarantee eventual consistency. Cueball: I mean, it does. [Closeup of Cueball.] Cueball: Eventual consistency is guaranteed by the 2nd law of thermodynamics. Cueball: Sooner or later this will all be a uniform heat bath. Cueball: Maximum entropy. [Back to Cueball and desk. Cueball is leaning back in his chair.] Laptop: Maximum entropy means no useful work can be done! Cueball: I'm getting a head start by doing no useful work now .

Cueball 's employer wants him to continue his work, possibly as a home-based remote worker as encouraged by the common current advice during the 2020 COVID-19 pandemic . The stated task is to "test the database" and "guarantee eventual consistency". Trying to avoid work, Cueball points out that the second law of thermodynamics itself "guarantees eventual consistency", as the universe is guaranteed to eventually die a heat death , at maximum entropy and perfect consistency . His boss responds that in a system that has reached maximum entropy, no work can be performed (as this requires a difference in energy states between two sources). Cueball claims that he's simply getting a head start on this. Eventual consistency has a double meaning here. In computing, many systems are distributed (spread out) across multiple servers, sometimes in very different parts of the world. When data changes -- like the number of views on a video or the likes on a social media post -- updating it across every server can be a challenge, and it's often not necessary to keep the data perfectly in sync everywhere. So the system will use eventual consistency instead. Each individual server will record changes, and after a certain amount of time or a certain amount of change, the results will be synced across the whole network. At any given moment, an individual server's data will be a little off -- but eventually everything will get recorded correctly. The title text constitutes another play on the words "heat bath", which can refer to the thermally uniform state of the universe at heat death . However, in this context, we can assume Cueball instead plans to prepare a literal warm bath for his own relaxation and enjoyment after or during (or instead of) his work. [Cueball sits at a home desk.] Laptop: I know it's hard to focus right now, but we should try to finish testing the DB. Cueball: Ughhhh. Cueball: Okay. [A frameless panel. Cueball still sitting at his desk. He has his hand on his chin.] Laptop: The system needs to guarantee eventual consistency. Cueball: I mean, it does. [Closeup of Cueball.] Cueball: Eventual consistency is guaranteed by the 2nd law of thermodynamics. Cueball: Sooner or later this will all be a uniform heat bath. Cueball: Maximum entropy. [Back to Cueball and desk. Cueball is leaning back in his chair.] Laptop: Maximum entropy means no useful work can be done! Cueball: I'm getting a head start by doing no useful work now .

Hair Growth Rate

Hair Growth Rate

https://www.xkcd.com/2316

https://www.explainxkcd.com/wiki/index.php/2316:_Hair_Growth_Rate

[White Hat and Ponytail are walking to the right.] White Hat: The average head has about 100,000 hairs. White Hat: And hair grows at about ½" per month. White Hat: Plus or minus. Ponytail: Okay... [They continue to walk while White Hat lift a hand up palm up.] White Hat: So our heads are producing an inch of hair every minute. Ponytail: I see. [They continue to walk.] Ponytail: I'm just glad it's evenly distributed. It would suck if we grew a single new five-foot-long hair every hour. [White Hat and Ponytail are seen in silhouette from a distance. White Hat has lifted a finger up and while Ponytail has thrown both her arms out to the sides.] White Hat: Hmm, would the hair grow steadily, or would it suddenly shoot out 5 feet on the hour? Ponytail: If the latter, what noise would it make? Ponytail: Ziiip? Pwiff? White Hat: Fwip? Ponytail: Blip. White Hat: Zhooop. Ponytail: Pew!

This strip is one of the simpler jokes that xkcd has done, being an observation on mathematics, biology, and human expectation. White Hat starts by sharing various facts about hair with Ponytail; hair count, individual hair growth rate, and finally total hair growth rate. Ponytail proceeds to snark about how unpleasant it would be if, rather than 100,000 hairs growing at a gross total of five feet (1.524m) per hour, humans grew a single hair at five feet per hour. The comic then delves into the absurdity of gradual versus spontaneous growth, and then the sound effects involved therein. The comic touches on what information can be obscured by just looking at aggregate values. A person whose 100,000 hairs grow a half-inch (1.27cm) per month experiences the same total new hair growth as a person with one hair growing five feet in an hour, but their grooming experiences would be very different. Likewise, a person with one hair growing steadily for an hour has the same average rate of hair growth as a person experiencing sudden hair growth on the hour, but the profile of instantaneous energy conversion and protein production would be very different. One of Ponytail's suggestions for what five feet of instantaneous hair growth might sound like is a sound effect generally used for directed-energy weapons ( Pew! ). We never see what sort of hairstyle White Hat has under his hat, but Ponytail's hair is fairly long. If she had to grow it out by one hair per hour, as in the title text, then it would take over eleven years before all 100,000 hairs had grown out. [White Hat and Ponytail are walking to the right.] White Hat: The average head has about 100,000 hairs. White Hat: And hair grows at about ½" per month. White Hat: Plus or minus. Ponytail: Okay... [They continue to walk while White Hat lift a hand up palm up.] White Hat: So our heads are producing an inch of hair every minute. Ponytail: I see. [They continue to walk.] Ponytail: I'm just glad it's evenly distributed. It would suck if we grew a single new five-foot-long hair every hour. [White Hat and Ponytail are seen in silhouette from a distance. White Hat has lifted a finger up and while Ponytail has thrown both her arms out to the sides.] White Hat: Hmm, would the hair grow steadily, or would it suddenly shoot out 5 feet on the hour? Ponytail: If the latter, what noise would it make? Ponytail: Ziiip? Pwiff? White Hat: Fwip? Ponytail: Blip. White Hat: Zhooop. Ponytail: Pew!

Pinouts

Pinouts

https://www.xkcd.com/2317

https://www.explainxkcd.com/wiki/index.php/2317:_Pinouts

[Caption at top] Pinouts Quick Reference Guide [Four common connectors are depicted - vertically, rather than the usual horizontal orientation.] [The first connector is a 19-pin HDMI connector.] [The nine pins on the left are labeled:] Data +5V +6VI +7VII Antidata Water Vacuum Amazon Copyright Pin Decorative [The ten pins on the right are labeled:] +3.3V DC -3.3V DC Tx Wx Rx Only Unknown +240V DC 5V AC GND Ground [The second connector is a 5-pin Micro USB connector.] [The five pins are labeled:] GND GND GND USB GND [The third connector is a 24-pin USB-C connector, with only the right side labeled.] [The twelve pins on the right are labeled:] +5V DC +3.3V DC +120V AC Boobytrap Pin (Pure Solder) Mechanical +3.3eV/C Candlepin Facebook Use +5V (Positrons) Pin Roulette GND SKY [The fourth and final connector is a 1-pin COAX connector.] [The one pin in the center is labeled:] Pin

Electronics connectors are designed to transport both information and power. A pinout diagram describes the function of each pin such as to communicate data, transport power, physical function (keying), etc. In this comic there is an absurd alternative to the actual pins used in connectors. The pin labels are references to many tech issues and attributes, and not all may be documented correctly here. Hardware hobbyists might feel excitement at seeing a unified specification for these common connectors, but the comic is of course humorous. The real life diagrams are as follows: HDMI , Micro USB , USB-C . The HDMI interface uses four pairs of shielded twisted-pair connectors, along with seven other connectors. ( Twisted pair means a wire is wrapped with the other wire that returns the current to the original device, thus minimizing electromagnetic noise. Shielding refers to wrapping a cable with a conductor to absorb the energy of noise.) Three of these pairs are for data (TMDS Data0, Data1, and Data2) and the other is a clock. These pairs take up three pins as one of them is a ground pin for the shielding wrapped around each pair. TMDS stands for " Transition-minimized differential signaling " and is also used in the DVI standard. DDC stands for "Display Data Channel" and is based on the I²C serial standard. It is used to allow the transmitting device to learn what formats of data the receiving device can accept. CEC stands for "Consumer Electronics Control" and is supposed to allow a single remote control to control multiple devices. "Hot Plug Detect" refers to hot-plugging, where a cable is connected to a device already turned on. The device should then ideally detect that the cable has been plugged in and respond appropriately. A ground pin is commonly found on USB and other pin connectors. At least one ground is necessary to complete the circuit, and some cables use multiple ground lines to distribute current or to support twisted pairs . However, there is no purpose served by having many more ground pins than data pins. Therefore, it seems rather silly for the micro USB to have 4 ground pins and only 1 functional "USB" pin. It also does not give much information about what the "USB" pin would do, as opposed to a standard pinout diagram. This diagram also leaves out the +5V power pin that is present in the real micro USB connector, which would render most USB peripherals unable to function. The ordering and count of the pins may be an allusion to Monty Python 's "Spam" sketch, in which one of the many Spam-related menu items is "Spam, Spam, Spam, egg, and Spam". The two sides of a USB C connector are labeled "A" and "B". These are rotationally symmetric, mostly. For example, B10 and B11 are Rx1, a separate twisted-pair for receiving information in Superspeed mode compared to A10 and A11's Rx2. This gives two Rx/Tx pairs for Superspeed use. CC1 and SBU1 are mirrored to CC2 and SBU2. However, the D, VBUS, and GND pins are perfectly mirrored. The fact that only half of the USB-C pins are documented might hint to an alternative way to manufacture connectors that can be inserted rotated by 180°: Make the receiver use only the right side of the pins and make the sender connect both the left and the right side so all Pins that might match a function are connected correctly no matter if the cable is rotated by 180°. However, doing this would result in only having one Rx/Tx pair for Superspeed use. A coaxial RF connector has two contacts - one pin, and the shield; typically the whole connector is labeled with whatever function/signal is carried by the pair. The joke here is that the label is technically correct (the best kind of correct), but not very useful to the end user, as it does not specify the voltage rating, impedance, connector size, or other useful information about the cable. Some serial data transmission systems, such as Ethernet , used coaxial cable early on as a low cost, widely available solution, however most of these have largely become obsolete. A common coaxial cable still widely in use is RG-6 , which is typically used to deliver satellite television, cable television, and cable Internet services in the United States and Canada. [Caption at top] Pinouts Quick Reference Guide [Four common connectors are depicted - vertically, rather than the usual horizontal orientation.] [The first connector is a 19-pin HDMI connector.] [The nine pins on the left are labeled:] Data +5V +6VI +7VII Antidata Water Vacuum Amazon Copyright Pin Decorative [The ten pins on the right are labeled:] +3.3V DC -3.3V DC Tx Wx Rx Only Unknown +240V DC 5V AC GND Ground [The second connector is a 5-pin Micro USB connector.] [The five pins are labeled:] GND GND GND USB GND [The third connector is a 24-pin USB-C connector, with only the right side labeled.] [The twelve pins on the right are labeled:] +5V DC +3.3V DC +120V AC Boobytrap Pin (Pure Solder) Mechanical +3.3eV/C Candlepin Facebook Use +5V (Positrons) Pin Roulette GND SKY [The fourth and final connector is a 1-pin COAX connector.] [The one pin in the center is labeled:] Pin

Dynamic Entropy

Dynamic Entropy

https://www.xkcd.com/2318

https://www.explainxkcd.com/wiki/index.php/2318:_Dynamic_Entropy

[One panel only with text and a few lines and arrows. There are two columns each with a heading. Beneath each heading is a quote written on four lines. Below the quote, in grey font, and indented, starting with a hyphen, with the text aligned to the right of this are five lines of text. This explains who the quote belongs too and where it was stated (in brackets at the end). From the bottom of each of these two gray text paragraphs gray curved arrows goes down to two gray lines. Below each of these two lines are one large word per line. They are again in black text.] Dynamic "It's impossible to use the word 'dynamic' in the pejorative sense... Thus, I thought 'Dynamic Programming' was a good name." - Richard Bellman, explaining how he picked a name for his math research to try to protect it from criticism ( Eye of the Hurricane , 1984) Entropy "You should call it 'Entropy'... No one knows what entropy really is, so in a debate you will always have the advantage." - John von Neumann, to Claude Shannon, on why he should borrow the physics term in information theory (as told to Myron Tribus) Dynamic Entropy [Caption below the panel:] Science Tip: If you have a cool concept you need a name for, try "Dynamic Entropy." Many of Buckminster Fuller 's designs and works were associated with the word " dymaxion ", a combination of the words "dynamic", "maximum", and "tension", all words that Fuller himself used a lot in talking about his work, and which are words that simultaneously have use in science and positive connotations in lay English.

This is another one of Randall's Tips , this time a Science Tip . This time it is a bit special since it came less than three weeks after another Science Tip: 2311: Confidence Interval (which was itself the first time that a non-Protip Tip type has been re-used). This is the first time a type of tip (that was not a Protip ) has been used for two "tips comics" in a row. This Science Tip suggests that if you have a cool new concept, you should call it dynamic entropy , hence the title. Dynamic programming is a mathematical optimization method and computer programming method developed by Richard Bellman in the 1950s. The History section of the Wikipedia article contains the full paragraph from Bellman's autobiography that contains the quote that is in the comic strip. Bellman describes how he was doing mathematical research funded by the military at a time when the Secretary of Defense had a literal pathological fear of the word "research", and by extension, "mathematical". Bellman borrowed the word "dynamic" from physics as being both accurate for his work and as a word that in plain English has positive connotations and is never used in a pejorative sense (expressing contempt or disapproval). The word "dynamic" itself comes from the Greek dynamikos , "powerful", which is a positive meaning in itself, and has been applied to topics in physics that are related to motion and forces and used in ordinary English to refer to things that exert power, force, growth, and change (dynamo, dynamite, and as an adjective). Even though those things aren't always good, when they're bad, we use other words instead (e.g. cancer undergoes metastasis , not "dynamism"). Entropy is a term from physics, specifically statistical mechanics, describing a property of a thermodynamic system. When Claude Shannon developed a mathematical framework for studying signal processing and communications systems, which became known as Information theory , he struggled to come up with a proper name for one mathematical concept in his theory that quantified amount of noise or uncertainty in a signal. Computer scientist John von Neumann noticed the similarity of the equations with some in thermodynamics and suggested, "You should call it entropy , for two reasons. In the first place your uncertainty function has been used in statistical mechanics under that name, so it already has a name. In the second place, and more important, no one really knows what entropy really is, so in a debate you will always have the advantage." (see History of information theory ). The naming of dynamic programming and of entropy in information theory are both examples of scientists choosing a name for what were at least partially very non-scientific seeming reasons. In one case because it has only positive and no negative connotations in plain English. In the other case because there is much confusion over the meaning of the word so Shannon would be free to adopt it in a new context. Randall is claiming that would make them great to put together to name some new concept; the combination will mean whatever the creator wants it to mean (even able to change mid-debate), and never sound bad the way that e.g. cold fusion has come to be. Even though the caption implies that "dynamic entropy" would be available as a new name, it has actually been used in physics [1] , probability [2] , computer science [3] , and even the term "dynamical entropy" in physics [4] [5] and bioscience [6] . In the title text Randall mentions that, even though his physics professors have continued to use the word "dynamical", "trying to normalize it" by repetitive usage, he remains convinced that it is not really a word. Presumably he doesn't like that it has two suffixes used to make words into adjectives, -ic and -al, as if "dynamic" wasn't already positive enough. The Free Dictionary discusses how -ic and -ical suffixes are confused in many common words and explains their different uses. The term "dynamical" in physics generally is used in " Dynamical system " or as an adjective to name a concept as applied to dynamical systems such as "dynamical entropy" [7] . [One panel only with text and a few lines and arrows. There are two columns each with a heading. Beneath each heading is a quote written on four lines. Below the quote, in grey font, and indented, starting with a hyphen, with the text aligned to the right of this are five lines of text. This explains who the quote belongs too and where it was stated (in brackets at the end). From the bottom of each of these two gray text paragraphs gray curved arrows goes down to two gray lines. Below each of these two lines are one large word per line. They are again in black text.] Dynamic "It's impossible to use the word 'dynamic' in the pejorative sense... Thus, I thought 'Dynamic Programming' was a good name." - Richard Bellman, explaining how he picked a name for his math research to try to protect it from criticism ( Eye of the Hurricane , 1984) Entropy "You should call it 'Entropy'... No one knows what entropy really is, so in a debate you will always have the advantage." - John von Neumann, to Claude Shannon, on why he should borrow the physics term in information theory (as told to Myron Tribus) Dynamic Entropy [Caption below the panel:] Science Tip: If you have a cool concept you need a name for, try "Dynamic Entropy." Many of Buckminster Fuller 's designs and works were associated with the word " dymaxion ", a combination of the words "dynamic", "maximum", and "tension", all words that Fuller himself used a lot in talking about his work, and which are words that simultaneously have use in science and positive connotations in lay English.

Large Number Formats

Large Number Formats

https://www.xkcd.com/2319

https://www.explainxkcd.com/wiki/index.php/2319:_Large_Number_Formats

[A panel only with text. At the top there is four lines of explanatory text. Below that are 2 columns with 5 rows of number formats. Each numerical format is in red, with black text explaining the format below it.] What the way you write large numbers says about you (Using the approximate current distance to Jupiter in inches as an example) 25,259,974,097,204 Normal person 25 trillion Normal person 25 billion Old British person 2.526x10 13 Scientist 2.525997x10 13 Scientist trying to avoid rounding up 2.526e13 or 2.526*10^13 Software developer 25,259,973,541,888 Software developer who forgot about floats 10 13 Astronomer {∅,{∅},{∅,{∅}},{∅,{∅},{... Set theorist 1,262,998,704,860 score and four Abraham Lincoln

This comic shows what the way you write large numbers says about you. Different people use different methods to express large numbers. And this comic claims it can tell something about you based on the way you format large numbers. In this way, the comic is similar in idea to 977: Map Projections , where it was your choice of map projections that could tell something about you. See the table below for each of the 10 different ways to express large numbers, plus the 11th mentioned in the title text. The number used as an example is the approximate distance from the planet Earth to the planet Jupiter as of the release day of the comic on June 12th 2020, in inches (1 inch = 2.54 cm). Two days after the release of the comic the following text could be found on Jupiter info on The Sky Live . The distance of Jupiter from Earth is currently 640,084,108 kilometers, equivalent to 4.278698 Astronomical Units. Light takes 35 minutes and 35.0908 seconds to travel from Jupiter and arrive on Earth. 64,008,410,800,000 cm / 2.54 cm/inches = 25,200,161,732,283 inches - much less than the number used in the comic. But Jupiter's distance to Earth changes quite quickly, and was decreasing at the time of the release of the comic. According to a graph of the distance as a function of time on The Sky Live, the distance on the release day was 643.1 million km. This will give 25.3*10 13 which the used number will round to. The used number 25,259,974,097,204 is equivalent to 641.6 million km. On June 13th the distance is given as 641.7 million km in the graph on The Sky Live, very close to the number used. As this was the day after the release of this comic, it seems like Randall used a different distance than the exact one for the release day. He may have also used an average for June which would be 642 million km based on the average of the distance on June and July 1st. [A panel only with text. At the top there is four lines of explanatory text. Below that are 2 columns with 5 rows of number formats. Each numerical format is in red, with black text explaining the format below it.] What the way you write large numbers says about you (Using the approximate current distance to Jupiter in inches as an example) 25,259,974,097,204 Normal person 25 trillion Normal person 25 billion Old British person 2.526x10 13 Scientist 2.525997x10 13 Scientist trying to avoid rounding up 2.526e13 or 2.526*10^13 Software developer 25,259,973,541,888 Software developer who forgot about floats 10 13 Astronomer {∅,{∅},{∅,{∅}},{∅,{∅},{... Set theorist 1,262,998,704,860 score and four Abraham Lincoln

Millennium Problems

Millennium Problems

https://www.xkcd.com/2320

https://www.explainxkcd.com/wiki/index.php/2320:_Millennium_Problems

[Randall, drawn as Cueball, is holding a hand palm up towards a screen where a projector on the floor in front of him is projecting a diagram. The projector is propped up on some kind of legs to project up on to the screen. Behind the projector Ponytail is watching him, while Cueball is looking away from Randall, while yelling after someone off-panel.] Randall: ...Proving that one of these four is unsolvable, but not which. If it's one of these , it would open a hole in Perlman's Poincaré conjecture proof. Randall: But it would also mean that solving either of the other two would re -prove Poincaré, and imply Hodge is isomorphic to... Cueball: Security?! [The slide on the projector screen shows a four-by-four matrix with 16 illegible entries, and also illegible text left and right of the matrix. The matrix is connected by four lines to four text segments written around the matrix. Two above (left and right), one to the right (at the bottom) and one below to the left. Arrows go between the right and left text at the top and both from the top left and the right text to the text at the bottom. The two to the right are connected by a line with an illegible equation written over this line, intersecting it. From the bottom text below the matrix an arrow goes down to another text beneath it. And from there an arrow goes up to the right text.] Hodge Riemann Navier-Stokes Birch/SD Poincaré wrong?? [Caption below panel:] I'm trying to make it so the Clay Mathematics Institute has to offer an eighth prize to whoever figures out who their other prizes should go to.

Randall , drawn as Cueball , is presenting a slide on the Millennium Prize Problems , seven problems designated by the Clay Mathematics Institute in the year 2000 as some of the most important unsolved problems in mathematics, a sort of successor to David Hilbert's list of 23 problems announced in 1900. The seven problems are: There are $1,000,000 prizes attached to each problem, although Grigori Perelman , the mathematician who proved the Poincaré conjecture , turned down his prize. Randall is attempting to demonstrate relationships between the various problems. According to the presentation, proving one might either disprove or prove others, and the proposed interactions between problems are so complex that the Institute might decide to award an additional prize to whoever can figure out which problem or problems have actually been solved by any given proof. This eighth prize could perhaps be funded by the award Perelman rejected. Randall has previously been banned from conferences for various provocative acts; presumably he's on his way to getting thrown out of the Clay Mathematics Institute as well, as the "other" Cueball is already calling security. However, this seems to be only these three people, thus not a conference to be banned from this time. The title text mentions that, if someone were to find a hole (a common expression for a deficiency or error) in Perelman's proof of the Poincaré conjecture, the famously reclusive author might show up again and fix the problem by applying the theoretical mathematics of differential geometry, where "hole" has a different meaning, to the figurative "hole" in the sequence of logical conclusions. The suggested method of enclosing the hole in a loop and then shrinking it away is reminiscent of the specific technique (Ricci flow with surgery) by which Perelman solved the Poincaré conjecture. [Randall, drawn as Cueball, is holding a hand palm up towards a screen where a projector on the floor in front of him is projecting a diagram. The projector is propped up on some kind of legs to project up on to the screen. Behind the projector Ponytail is watching him, while Cueball is looking away from Randall, while yelling after someone off-panel.] Randall: ...Proving that one of these four is unsolvable, but not which. If it's one of these , it would open a hole in Perlman's Poincaré conjecture proof. Randall: But it would also mean that solving either of the other two would re -prove Poincaré, and imply Hodge is isomorphic to... Cueball: Security?! [The slide on the projector screen shows a four-by-four matrix with 16 illegible entries, and also illegible text left and right of the matrix. The matrix is connected by four lines to four text segments written around the matrix. Two above (left and right), one to the right (at the bottom) and one below to the left. Arrows go between the right and left text at the top and both from the top left and the right text to the text at the bottom. The two to the right are connected by a line with an illegible equation written over this line, intersecting it. From the bottom text below the matrix an arrow goes down to another text beneath it. And from there an arrow goes up to the right text.] Hodge Riemann Navier-Stokes Birch/SD Poincaré wrong?? [Caption below panel:] I'm trying to make it so the Clay Mathematics Institute has to offer an eighth prize to whoever figures out who their other prizes should go to.

Low-Background Metal

Low-Background Metal

https://www.xkcd.com/2321

https://www.explainxkcd.com/wiki/index.php/2321:_Low-Background_Metal

[Black Hat stands behind Megan who addresses Cueball who stands on the other side of a table with a machine. The machine is a rectangular box with a small dome with one large and two small antennas on top. It seems to point in Cueball's direction as it has a broad protrusion at the back and protrusion at the front that gets smaller towards the tip. The word "Time" is written on the side, and below that is possibly more illegible text.] Megan: Our time machine works. Megan: But we're almost out of low-background metal. Cueball: What's that? [Close-up on Megan who lifts her hand palm up.] Megan: Modern metal is contaminated by fallout from nuclear testing, and lead also has natural radioactivity that fades over time. Megan: To shield sensitive equipment, physicists use lead from sunken Roman ships. Megan: But shipwreck lead is hard to find. [Back to the original setting, Megan has turned to Black Hat, who has his hand on his chin.] Black Hat: How much do we have? Megan: Enough for one trip through time. Black Hat: Hmmm... [The three are now in a helicopter, with Megan piloting, Cueball as a passenger in the back, and Black Hat firing a flamethrower at a Roman ship beneath them through the window behind the cockpit. Two sailors with Roman type helmets are looking on as the stern of their ship catches fire. One of them throwing his arms out to the side. The intact sail is still up behind them and behind that another sailor jumps into the water, down to a fourth sailor already in the water. Two already-burning ships can also be seen to the left of the ship under attack. One is burning all over, with the mast still up but the sail long gone, and the third ship is almost completely sunk, but the part above the water is aflame. Seven small clouds are around the helicopter in the sky.] Flamethrower: Fwooosh

In this comic, a team including Megan and Black Hat who have invented a time travel machine presents it and their problems to Cueball . Time travel is a common trope in science fiction, and specifically here on xkcd , and such a discovery would be likely to change the world as we know it. However, Megan and Black Hat's machine requires the use of "low-background" metal, which is in short supply. Megan explains that, while delicate equipment is often shielded from radiation by lead, metal produced in modern times is contaminated by nuclear fallout in the atmosphere, which means that the shielding itself has enough radioactivity to interfere with highly delicate equipment. In order to shield this equipment, "low-background metal" is salvaged from sunken ships. Lead ingots from Roman cargo have been used in experiments. The Roman lead was produced before atmospheric nuclear tests occurred [ citation needed ] and therefore did not have resulting radionuclides in the air used in its manufacture. When it is extracted, lead is naturally contaminated with the radioactive isotope Pb-210, with a 22 year half-life. Because it has spent many centuries continually underwater, it is both shielded from radioactive particles, and has had time for natural radioactivity to fade. The number of shipwrecks of that age that can be found and successfully salvaged for metal is quite small, which puts this material in short supply. Megan mentions that they have only enough for a single trip. The team realizes (apparently at Black Hat 's suggestion), that a solution is to use their single trip to take modern military hardware back to the era of the Roman Empire and use it to sink multiple ships. This would both provide for many more shipwrecks to salvage, and give the team a good idea of where those wrecks were, when they returned to modern times. They could also specifically target ships that were in waters that are well-suited for salvage operations. However, while this might be a pragmatic solution, going back in time to sink ships and murder the occupants doesn't seem like a particularly morally acceptable solution, [ citation needed ] not to mention opening up potential time travel paradoxes such as what if one of the ship occupants killed was an ancestor to one of the protagonists? If this were a real scenario, there would probably be less drastic solutions available, such as purchasing quantities of lead from the time (would need to convincingly impersonate a local and have something that could be used as currency) and dropping them in the ocean from a (rented) non-destroyed ship, which as a bonus eliminates the need to extract it from the charred remains of a ship later. Using time travel to retrieve items from the past that are not available in the present is a frequent trope in time travel-related media. Frequently, it is done with the goal of making money , but other purposes are used as well. In the Star Trek movie The Voyage Home , time travel is used to retrieve whales and transport them to the present. In the book Timeline , time travel is used to record historical events for entertainment purposes. In the movie Avengers: Endgame , time travel is used to retrieve minerals important to a future plan. In the movie Back to the Future , when Marty tells Doc that the time machine runs on plutonium, Doc exclaims, "I'm sure that in 1985, plutonium is available at every corner drug store, but in 1955, it's a little hard to come by" (from this transcript ). Low-background steel is the most famous kind of low-background metal, used in real life for highly sensitive particle detectors in physics and medicine, and is salvaged from ships sunk before 1945 (the Trinity nuclear test ). Since this is steel, the ships used typically date back to World War I or World War II. (It should be noted that the vast majority of applications that previously required special low-background steel can now once again use ordinary newly-produced steel, as the concentration of radionuclides in the atmosphere has declined almost to pre-1945 levels in the decades since the cessation of atmospheric nuclear testing, due partly to the shorter-lived of these radionuclides having decayed away and partly to processes such as the carbon cycle having removed most of the still-extant radionuclides from the atmosphere.) The title text refers to Greek fire , which was an incendiary weapon invented and employed by the Byzantine empire. It was a flammable liquid, famously said to burn on water, that was used in naval combat to set fire to enemy ships. As it was a closely-guarded military secret, many of the details have been lost to time, and modern chemists have only been able to develop educated guesses of what it probably was. Randall proposes a rather outlandish alternative hypothesis: that all records of Greek fire were actually in reference to the modern weapons used by the time travelers. It is also notable that, if the time machine was taken to the time of the classical Roman empire, Greek fire would not yet have been a known term. Perhaps the weapon wielded by the time travelers was later conflated with the Byzantines' weapon, or perhaps the time machine was taken to a period a few centuries later than classical Rome. In 1063: Kill Hitler a single-use time machine is available. It is also used by Black Hat. However, due to the way the time machine in this comic is used, it must be assumed that they can use it again after the salvage of lead from the sunken ships. [Black Hat stands behind Megan who addresses Cueball who stands on the other side of a table with a machine. The machine is a rectangular box with a small dome with one large and two small antennas on top. It seems to point in Cueball's direction as it has a broad protrusion at the back and protrusion at the front that gets smaller towards the tip. The word "Time" is written on the side, and below that is possibly more illegible text.] Megan: Our time machine works. Megan: But we're almost out of low-background metal. Cueball: What's that? [Close-up on Megan who lifts her hand palm up.] Megan: Modern metal is contaminated by fallout from nuclear testing, and lead also has natural radioactivity that fades over time. Megan: To shield sensitive equipment, physicists use lead from sunken Roman ships. Megan: But shipwreck lead is hard to find. [Back to the original setting, Megan has turned to Black Hat, who has his hand on his chin.] Black Hat: How much do we have? Megan: Enough for one trip through time. Black Hat: Hmmm... [The three are now in a helicopter, with Megan piloting, Cueball as a passenger in the back, and Black Hat firing a flamethrower at a Roman ship beneath them through the window behind the cockpit. Two sailors with Roman type helmets are looking on as the stern of their ship catches fire. One of them throwing his arms out to the side. The intact sail is still up behind them and behind that another sailor jumps into the water, down to a fourth sailor already in the water. Two already-burning ships can also be seen to the left of the ship under attack. One is burning all over, with the mast still up but the sail long gone, and the third ship is almost completely sunk, but the part above the water is aflame. Seven small clouds are around the helicopter in the sky.] Flamethrower: Fwooosh

ISO Paper Size Golden Spiral

ISO Paper Size Golden Spiral

https://www.xkcd.com/2322

https://www.explainxkcd.com/wiki/index.php/2322:_ISO_Paper_Size_Golden_Spiral

[Caption inside panel:] The golden ratio is everywhere! [Picture of the ISO standard paper sizes (i.e. A1, A2, etc.) placed so that they fit together perfectly, overlaid with a spiral resembling that of the golden ratio] [A rectangle in landscape orientation with width= height*sqrt(2) is divided into two halves by a vertical line. The left half, a rectangle in portrait orientation, with height=width*sqrt(2), is labeled "A1". The right half (also portrait) is divided into two halves by a horizontal line; the rectangle above this horizontal line (landscape) is labeled "A2". Below this horizontal line there is a landscape rectangle which is divided into two portrait rectangles by a vertical line. The right half is labeled "A3", the left half is divided into two halves by a horizontal line. The lower half is labeled "A4", the upper half is divided again, with its left half labeled "A5". The series continues like this until "A10". ] [Symbolically: A1 -right,up- A2 -down,right- A3 -left,down- A4 -up,left- A5 -right,up- A6 -down,right- A7 -left,down- A8 -up,left- A9 -right,up- A10.] [A red spiral starts at the lower left corner of A1, passes through the upper right corner of A1 which is also the upper left corner of A2, continues through the upper right corner of A3, lower right of A4, lower left of A5, etc, and after passing through the lower right corner of A10 continues to what would be the lower left corner of A11 and the upper right corner of A12.] [Caption below panel:] How to annoy both graphic designers and mathematicians

This comic strip is about how to annoy graphic designers and mathematicians, much like 590: Papyrus and 1015: Kerning . An easy way to annoy many mathematicians is to make fanciful claims about the Golden Ratio . It's been claimed, with varying levels of credibility, to be detectable in many natural and human-made situations, often with the dubious subjective claim that using the ratio in some particular way makes an image more "beautiful". The Golden Spiral is a spiral whose growth factor is this ratio; a common (though slightly geometrically inaccurate) way to illustrate the spiral is to draw curves through a set of squares whose side lengths shrink according to the Golden Ratio. The result looks rather like Randall's drawing here. However, Randall hasn't used the Golden Ratio at all; he's just drawn a spiral ( not the Golden Spiral) through a common diagram showing the A Series of standard paper sizes, but in landscape instead of portrait (this diagram is commonly drawn in portrait). These papers aren't squares at all, but rectangles whose side lengths shrink by a factor of the square root of 2. Additionally, the paper sizes shrink by a factor of one half, so the area is filled in a geometric series. This is sometimes called a silver rectangle, although the Silver ratio is actually 1+√2. By mistaking the A Series for something connected with the Golden Ratio, and perpetuating the tradition of making dubious claims about the Golden Ratio, Randall has successfully annoyed both graphic designers and mathematicians. The title text is a similarly themed joke, based partly on the fact that the US uses customary units while the vast majority of the rest of the world uses SI units . The 11/8.5 ratio is the length/width ratio of US Letter paper, which is 11 inches by 8.5 inches (another common size in the United States is US Legal, which is 14" by 8.5"). The value of π/4 radians is indeed equal to 45 degrees, although Randall takes the cosine in one case and uses the raw angle in the other case in order to get a close coincidence of values. The width and length of A Series paper ( ISO 216 ) is always given in whole millimeters, and the width/length ratio is very close to cos(45°) (which is 1/√2=0.707…) As for US Letter paper: to 4 decimal places, 8.5/11 = 0.7727 and π/4 = 0.7854. In reality, the usage of radians vs. degrees is not a geographic or political decision, but generally is delineated by profession. Most engineering and science fields measure angles in degrees or fractions of degrees (arcseconds, or even milliarcseconds in fields like astronomy), while mathematicians and physicists generally use radians. Civil engineers may refer to the slope of a road by its grade , which is commonly expressed in terms of the tangent of the angle to the horizontal (either as a percentage or a ratio); for angles up to ~10°, this is close to the value of the angle in radians. The difference between the "real" Golden Spiral squares and Randall's version is approximately either .2038 (for √2-1.6180…) or .08907 ((1/√2)-1.6180…), depending on which way you're counting. Either way, the difference would be very noticeable.) The spiral shown is approximately a logarithmic spiral with a growth factor of √2, although it has been edited slightly to make it fit neatly inside the rectangles. If the center of the spiral is at the origin, it may be graphed with r = C*2^(θ/π), for any positive constant C. In 1488: Flowcharts a golden spiral has been laid in over the chart. That comic is a link that goes to the spiral page on xkcd. [Caption inside panel:] The golden ratio is everywhere! [Picture of the ISO standard paper sizes (i.e. A1, A2, etc.) placed so that they fit together perfectly, overlaid with a spiral resembling that of the golden ratio] [A rectangle in landscape orientation with width= height*sqrt(2) is divided into two halves by a vertical line. The left half, a rectangle in portrait orientation, with height=width*sqrt(2), is labeled "A1". The right half (also portrait) is divided into two halves by a horizontal line; the rectangle above this horizontal line (landscape) is labeled "A2". Below this horizontal line there is a landscape rectangle which is divided into two portrait rectangles by a vertical line. The right half is labeled "A3", the left half is divided into two halves by a horizontal line. The lower half is labeled "A4", the upper half is divided again, with its left half labeled "A5". The series continues like this until "A10". ] [Symbolically: A1 -right,up- A2 -down,right- A3 -left,down- A4 -up,left- A5 -right,up- A6 -down,right- A7 -left,down- A8 -up,left- A9 -right,up- A10.] [A red spiral starts at the lower left corner of A1, passes through the upper right corner of A1 which is also the upper left corner of A2, continues through the upper right corner of A3, lower right of A4, lower left of A5, etc, and after passing through the lower right corner of A10 continues to what would be the lower left corner of A11 and the upper right corner of A12.] [Caption below panel:] How to annoy both graphic designers and mathematicians

Modeling Study

Modeling Study

https://www.xkcd.com/2323

https://www.explainxkcd.com/wiki/index.php/2323:_Modeling_Study

[There are two columns.] [The column on the left is a piece of paper labeled "Empirical Study". The paper consists of the sections "Abstract", "Introduction", "Methods", "Results", and "Discussion". Each section consists of several horizontal lines meant to represent blocks of text. All sections except "Abstract" have gray, dulled text, while "Abstract" has fully black text to separate it from the other sections. In the middle of the "Abstract" section, there is a large red rectangle. Inside this rectangle is the word "Problem" in large red letters.] [The column on the right is a piece of paper labeled "Modeling Study". It consists of the same sections with the same highlighting, but the large red rectangle with the word "Problem" is in the "Methods" section instead of the "Abstract" section. Because of this, it is dulled to match the rest of the "Methods" section.] [There is a curvy black arrow pointing from the red box in the paper on the left to the red box in the paper on the right.] [Caption below the panel:] A mathematical model is a powerful tool for taking hard problems and moving them to the methods section.

In this comic, a humorous comparison is drawn between two common types of scientific studies: empirical research , where an experiment is designed to test a scientific theory, and mathematical modeling , where mathematical formulations are produced to predict how physical systems behave under given circumstances. In empirical studies, hard questions about the limitations of existing theory tend to be addressed in the abstract, which is the brief summary of the paper that is presented at the beginning of most scientific articles. In modeling studies, assumptions based on existing theory are built into the model, and any problems associated with these assumptions tend to be discussed in the methods section, which outlines the design of an experiment in the case of an empirical study, or how the model was designed and the reasoning behind the choices made in the case of a modeling study. In the empirical study, the proverbial "big red problem box" is stated up-front where everyone who finds the paper will read it, while in the modeling study, it's buried in the middle of the paper, where it's less likely to be read. The caption opens like a typical statement in favor of modeling studies, "A mathematical model is a powerful tool for taking hard problems," but while a researcher who works with models might go on to say "...and breaking them down," or "...and studying them in ways that would be impractical for empirical studies," Randall concludes that they can't actually make hard problems any easier. His title text, "You've got questions, we've got assumptions," plays on the slogan of the now-defunct electronics chain Radio Shack of "You've got questions, we've got answers" by pointing out that any answers provided are built on assumptions by the modelers. In other words, garbage in, garbage out . Randall doesn't call this a "tip" , but it does fit in with his science tip in 2311: Confidence Interval , namely, that "If your model is bad enough, the confidence intervals will fall outside the printable area." Much as that tip suggests that a model's results can be made to look more impressive by hiding the error bounds outside the printed area of a graph, this comic strip suggests that acknowledgments of problems can be moved to less-trafficked parts of the paper by switching from empirical to modeling studies. [There are two columns.] [The column on the left is a piece of paper labeled "Empirical Study". The paper consists of the sections "Abstract", "Introduction", "Methods", "Results", and "Discussion". Each section consists of several horizontal lines meant to represent blocks of text. All sections except "Abstract" have gray, dulled text, while "Abstract" has fully black text to separate it from the other sections. In the middle of the "Abstract" section, there is a large red rectangle. Inside this rectangle is the word "Problem" in large red letters.] [The column on the right is a piece of paper labeled "Modeling Study". It consists of the same sections with the same highlighting, but the large red rectangle with the word "Problem" is in the "Methods" section instead of the "Abstract" section. Because of this, it is dulled to match the rest of the "Methods" section.] [There is a curvy black arrow pointing from the red box in the paper on the left to the red box in the paper on the right.] [Caption below the panel:] A mathematical model is a powerful tool for taking hard problems and moving them to the methods section.

Old Days 2

Old Days 2

https://www.xkcd.com/2324

https://www.explainxkcd.com/wiki/index.php/2324:_Old_Days_2

[In a slim panel, Cueball and Hairbun are walking together to the right. Hairbun has her palm raised.] Cueball: What was the Internet like in the olden days, for a developer? Hairbun: Oh, things were very different. [Cueball and Hairbun have stopped walking. Zoomed in on Hairbun.] Hairbun: The cloud was a lot smaller. It was called a "mainframe" and it was near Sacramento. Hairbun: It was on the state landline, so the whole industry paused when the governor had to make a phone call. [Zoomed back out. Hairbun has her palm raised.] Hairbun: There was no memory protection. If you wanted to write to an address, you would call around to ask whether anyone else was using it. Hairbun: Often Bill Gates would say he was, even when he wasn't. That's how Microsoft got its early foothold. Cueball: Wow. [Zoomed back in Hairbun. Cueball responds off-screen.] Hairbun: "Git" was originally a van that circled around gathering data tapes to copy and distribute. We all took turns driving it. Hairbun: When you saw it coming you'd blow an air horn to request that it pull over. Hairbun: That's where "pull request" came from. Cueball (off-screen): Oh, neat! [Cueball and Hairbun continue walking to the right. Hairbun has her palm raised.] Hairbun: Before terminals, we all used punch cards, which were originally developed to control looms. Hairbun: Early mainframes would produce a sweater each time you ran your code. Hairbun: Eventually we got them to stop. We had enough sweaters.

In this sequel to 1755: Old Days , which was released more than 3.5 years ago, the conversation continues, as if no time has passed, between (young) Cueball and (old) Hairbun about computer programming in the past. As in the first comic in this series , Cueball, having only a faint idea of just how difficult and byzantine programming was "in the old days", asks Hairbun to enlighten him on the specifics. Hairbun promptly seizes the opportunity to screw with his head. The new claims: [In a slim panel, Cueball and Hairbun are walking together to the right. Hairbun has her palm raised.] Cueball: What was the Internet like in the olden days, for a developer? Hairbun: Oh, things were very different. [Cueball and Hairbun have stopped walking. Zoomed in on Hairbun.] Hairbun: The cloud was a lot smaller. It was called a "mainframe" and it was near Sacramento. Hairbun: It was on the state landline, so the whole industry paused when the governor had to make a phone call. [Zoomed back out. Hairbun has her palm raised.] Hairbun: There was no memory protection. If you wanted to write to an address, you would call around to ask whether anyone else was using it. Hairbun: Often Bill Gates would say he was, even when he wasn't. That's how Microsoft got its early foothold. Cueball: Wow. [Zoomed back in Hairbun. Cueball responds off-screen.] Hairbun: "Git" was originally a van that circled around gathering data tapes to copy and distribute. We all took turns driving it. Hairbun: When you saw it coming you'd blow an air horn to request that it pull over. Hairbun: That's where "pull request" came from. Cueball (off-screen): Oh, neat! [Cueball and Hairbun continue walking to the right. Hairbun has her palm raised.] Hairbun: Before terminals, we all used punch cards, which were originally developed to control looms. Hairbun: Early mainframes would produce a sweater each time you ran your code. Hairbun: Eventually we got them to stop. We had enough sweaters.

Endorheic Basin

Endorheic Basin

https://www.xkcd.com/2325

https://www.explainxkcd.com/wiki/index.php/2325:_Endorheic_Basin

[Megan, holding a glass of water up in one hand, is talking to Beret Guy, who has water surrounding his feet, with small droplets falling off the two small water triangles that cover his feet. The water in her glass is leaning towards Beret Guy.] Megan: Why are your feet wet? Beret Guy: I'm an endorheic basin! [Megan looks down at her glass as the water in it is flying out towards Beret Guy's arm, which he has stretched out towards the glass.] Megan: Huh? Beret Guy: Nearby water flows toward me, not the ocean. Beret Guy: See? Megan: Oh, cool. [At the top of this panel is a box with text being said by Beret Guy to Megan. Beneath it is a depiction of what he is explaining to Megan. Beret Guy is shown standing in a bathroom, with a towel around his waist. Almost his entire body is covered completely in water, except most of his head above mouth level, and both his feet are beneath the water bubble. He yells to someone outside the bathroom. A shower-tray or partially sunken bathtub can be seen to the left with a closed shower curtain across it. To the right of him is the sink with mirror above it. Further right is the door. The floor is tiled.] Beret Guy - narrating: The most annoying part is drying off after a shower. Beret Guy: Can someone bring me the siphon? [Back to the situation from the first panel, although Megan has lowered her glass a bit. The glass seems to be as full as in the first panel though, even though Beret Guy now also has water on his arm where it was pulled out off Megan's glass in panel 2.] Beret Guy: But I have to get rid of it or I'll develop salt flats. Beret Guy: Anyway, let me know if you need any minerals!

Yet another comic with one of Beret Guy's strange powers . This time he attracts water so it flows to him rather than running out towards the nearby oceans. He thus claims he is an endorheic basin , hence the title. An endorheic basin is a limited drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation. The Caspian Sea in Asia is the largest such basin. It is debated if it is a lake or a sea (it is salty, but not connected to the oceans). If it is a lake then it is the world's largest lake. Real-life endorheic basins do not attract water in any unusual ways. Rather, they form when low-lying, inland areas receive water from rivers and streams, but not enough to flood them completely and allow the water to overflow into an ocean. As the surface of the lake grows, so do the rate of evaporation and seepage into the ground, until they're equivalent to the inflow of water (at least, on a yearly average). Obviously, Beret Guy's inexplicable effect on water is distinct from the way actual endorheic basins function. The panel showing Beret Guy after a shower looks similar to what could happen in a space station if you have liquid water in zero gravity. The water in this environment sticks to any surface it encounters. [ citation needed ] See for instance the start of this video Water in zero gravity and this one Wringing out Water on the ISS - for Science! to see how water reacts to human skin in zero gravity. It is thus almost impossible for him to dry off after a shower. It seems like the water that is attracted to him is still somewhat subject to gravity, as it pools downwards upon him; presumably he knows to finish showering before it floods over his face. In fact he needs someone to come with a siphon to get rid of the water. A siphon is a hose or u-shaped pipe, where the downward pipe is longer than the upward section. Thus the water falling in the downward section creates a pull lifting the water in the upward section up to the highest point, from which it will flow down pulling more water up. As the endorheic basin caused by Beret Guy seems to have a limited reach, placing one end of the pipe sufficiently far outside creates a similar effect: The water outside Beret Guy's area of effect flows down under the influence of gravity, creating a pull lifting the water near him "up" out of the endorheic basin. Randall made a what if? about siphons in #143: Europa Water Siphon . As with real endorheic basins, if the water is allowed to sit, it will eventually evaporate, but he notes that he'll "develop salt flats". Water from rivers carry salts, typically in low concentrations, and if a lake lacks outflows, the salts build up over time, as the water evaporates. If a salt lake evaporates completely, it can create salt flats (or salt pans), like those near Salt Lake City in Utah , e.g. the Bonneville Salt Flats . These salts come in a variety of forms, including minerals. Sometimes, endorheic basins have high enough concentrations of dissolved minerals to be worth extracting, which is presumably what he means by "let me know if you need any minerals". There may also be a contrived pun here, in that "flats" is a description of various types of footwear (among them: women's shoes that are not high-heeled and ballet shoes not specifically reinforced for advanced 'pointe' dancing), and the water would clearly leave the 'flats' on his feet. In the title text, Beret Guy mentions his "biggest fear" due to his water attracting abilities is being flooded to by "colonial engineers" in order for them to use him and the water to generate electricity. This may be a reference to the Qattara Depression Project . The Qattara depression is a low-lying region near the Egyptian coast. For nearly a century, there have been proposals to dig a canal from the sea to flood this depression, deliberately creating a huge endorheic basin. By placing hydroelectric dams along the canal, the proposals hoped to generation huge amounts of electricity. At least one proposal included the use of nuclear explosions to create the canal, which may help to explain why he considers this his biggest fear. He then mentions that his "biggest hope", due to his ability, is that he will generate sailing stones . Sailing stones (also known as sliding rocks, walking rocks, rolling stones, and moving rocks), are a geological phenomenon where rocks move and inscribe long tracks along a smooth valley floor without human or animal intervention. The movement of the rocks occurs when large ice sheets a few millimeters thick and floating in an ephemeral winter pond start to break up during sunny days. Frozen during cold winter nights, these thin floating ice panels are driven by wind and shove rocks at speeds up to 5 meters per minute. The Racetrack Playa , an endorheic basin in Death Valley, is one of the most famous locations for sailing stones. This comic came out just a bit more than a month after the previous comic with one of Beret Guy's strange powers, 2310: Great Attractor , in which strange forces exerted a pull on Beret Guy. It does not appear that he himself is drawn to water, and we cannot determine if the Great Attractor is drawn to him, so Newton's Third Law may be constantly being broken, along with the more obvious scientific impossibilities that surround Beret Guy. [Megan, holding a glass of water up in one hand, is talking to Beret Guy, who has water surrounding his feet, with small droplets falling off the two small water triangles that cover his feet. The water in her glass is leaning towards Beret Guy.] Megan: Why are your feet wet? Beret Guy: I'm an endorheic basin! [Megan looks down at her glass as the water in it is flying out towards Beret Guy's arm, which he has stretched out towards the glass.] Megan: Huh? Beret Guy: Nearby water flows toward me, not the ocean. Beret Guy: See? Megan: Oh, cool. [At the top of this panel is a box with text being said by Beret Guy to Megan. Beneath it is a depiction of what he is explaining to Megan. Beret Guy is shown standing in a bathroom, with a towel around his waist. Almost his entire body is covered completely in water, except most of his head above mouth level, and both his feet are beneath the water bubble. He yells to someone outside the bathroom. A shower-tray or partially sunken bathtub can be seen to the left with a closed shower curtain across it. To the right of him is the sink with mirror above it. Further right is the door. The floor is tiled.] Beret Guy - narrating: The most annoying part is drying off after a shower. Beret Guy: Can someone bring me the siphon? [Back to the situation from the first panel, although Megan has lowered her glass a bit. The glass seems to be as full as in the first panel though, even though Beret Guy now also has water on his arm where it was pulled out off Megan's glass in panel 2.] Beret Guy: But I have to get rid of it or I'll develop salt flats. Beret Guy: Anyway, let me know if you need any minerals!

Five Word Jargon

Five Word Jargon

https://www.xkcd.com/2326

https://www.explainxkcd.com/wiki/index.php/2326:_Five_Word_Jargon

[White Hat, holding his palm up, is speaking to Cueball, who is typing with both hands on his smartphone. What he types is indicated with a jagged line going up from his phone.] White Hat: Yeah, I learned about it when I was researching anomalous electroweak sphaleron transition baryogenesis. Cueball: Cooool. Text on phone: A-n-o-m- [Caption below the panel:] My Hobby: Collecting really satisfying-sounding five-word technical phrases. Current favorites Transjugular intrahepatic portosystemic shunt placement Generalized autoregressive conditional heteroskedasticity model Unicellular diazotrophic cyanobacteria group A Anomalous electroweak sphaleron transition baryogenesis

This is another comic in Randall 's My Hobby series , the first of two hobby comics released in the same week, the second being 2328: Space Basketball . This hobby involves "collecting" and presumably using five-words-long technical jargon. In the comic, White Hat uses a phrases with five such words while talking to Randall (as Cueball ), causing Randall to exclaim "cool" (as in what a cool sentence), and then proceed to type the phrase into his phone to add to his list of favorite Five Word Jargon. Randall then proceeds to list his current favorites among really satisfying five word technical phrases (or jargon) as a caption below the panel, with White Hat's phrase as the last, possibly the newest. Maybe it was the one that caused Randall to consider other phrases and make this comic. In the title text, Randall says that he has another much harder hobby, which is to engineer situations where he can use more than one of his favorite phrases. It would seem difficult to combine any of the four listed phrases in a given conversation, as they are from four separate fields (medicine, economics/statistics, biology, and physics/cosmology). However, he said "situations", which is broader term than "conversations". For example, someone could arrange for experts on these fields to deliver TED talks on these topics, so that he could introduce them by saying "today, we will learn about..." and list the phrases, but Randall cannot, because he has been banned from TED . At least he has succeeded in using them together in this comic. This technique has also been used by the [ [1] ], who uses three-word phrases to create excuses for why he won't fix someone's computer when they ask. A transjugular intrahepatic portosystemic shunt (TIPS) is "an artificial channel within the liver that connects the inflow portal vein and the outflow hepatic vein". It is used to treat various intestinal bleeding. This term can be found in this publication: https://pubmed.ncbi.nlm.nih.gov/16850140/ transjugular the shunt is inserted via the jugular vein intrahepatic within the liver portosystemic blood is shunted from the portal vein (draining blood from the intestines to the liver) to the systemic circulation (returning blood from the liver to the heart) shunt a tube within the body that bypasses the normal flow of something (whether a natural defect, or an artificial device) placement the operation to insert it A generalized autoregressive conditional heteroskedasticity (GARCH) model is a statistical model for economic research. An autoregressive model of a time series is one that uses previous values of the time series to predict the next value. A conditional probability model is one that divides data into inputs and outputs and models the relation between them using a conditional probability distribution of the outputs given the inputs. A heteroskedastic distribution is one in which the variance (or standard deviation) of a random variable is not the same across all values of the variable. This phrase can be found in this publication: https://www.scirp.org/html/11-1241334_99870.htm Generalized making more general, as opposed to a specific model autoregressive using previous values to predict future values. conditional outputs depending on specific inputs (in the sense of, "funding is conditional on meeting targets") heteroskedasticity the property where the variance (that is, the random difference between an expected value and its observed value) itself varies in response to some variable. From Greek, meaning "different dispersion". For example, a graph of expenditure on food against income shows higher randomness at higher income levels, because poor people always eat cheaply, while rich people sometimes do and sometimes don't. model a set of equations that attempt to describe some property of the world for the purpose of analysis A unicellular diazotrophic cyanobacterium is a single-celled type of bacteria that is able to convert atmospheric nitrogen into a more usable form, and also generates oxygen through photosynthesis. The term can also be found in this publication: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303622/ unicellular Consisting of only one cell ( Unicellular organism ), such as all bacteria. The opposite is multicellular , which includes almost all other lifeforms like animals, plants, algae, etc. diazatrophic Having the property of fixing nitrogen from the air into other chemicals. cyanobacterium A fairly broad category of bacteria which often play an important role in various habitats, using photosynthesis to convert light energy to oxygen. "Cyano" refers to their general blue colour, not cyanide. group A the "first" group of several groups in a controlled experiment, or a scientific study; in this case, it is the first of several (B, C) groups of phylogenetically-related organisms, for which there is as yet no published scientific name, see here: https://www.researchgate.net/publication/308030272_The_small_unicellular_diazotrophic_symbiont_UCYN-A_is_a_key_player_in_the_marine_nitrogen_cycle . This is a term from Particle physics / cosmology . Baryons are subatomic particles containing an odd number of quarks; protons and neutrons are the most familiar examples. Baryogenesis is the hypothetical physical process that took place during the early universe that produced more matter than antimatter in the observable universe (or it could be any process that produces baryons). Sphaleron is a static (time-independent) solution to the electroweak field equations of the Standard Model of particle physics, and is involved in certain hypothetical processes that change the number of baryons or leptons (e.g. forming baryons and removing leptons). It is believed that the electroweak interaction is responsible for baryogenesis, but that at the temperatures involved (~10 15 K), sphaleron interactions would wipe out any excess of baryons; therefore, for baryogenesis to "stick", it must have occurred at the transition out of the electroweak era...unless there were some kind of anomaly in the formation or interaction of sphalerons. Google reports no matches (other than this page) for the entire phrase in quotes, but shows about 70 results unquoted, indicating it finds only partial matches. Anomalous Deviating from normal or expected electroweak A theory combining electromagnetism and the weak interaction , two of the four fundamental forces (alongside the strong interaction and gravity) in the Standard Model of particle physics. sphaleron a single, time-independent, solution to electroweak field equations, represented as a saddle point between two different low energy equilibria transition change baryogenesis creating baryons, which are a category subatomic particles containing an odd number of quarks, including protons and neutrons. (-genesis is a general suffix for a process which creates something; eg carcinogenesis means, creating cancer) [White Hat, holding his palm up, is speaking to Cueball, who is typing with both hands on his smartphone. What he types is indicated with a jagged line going up from his phone.] White Hat: Yeah, I learned about it when I was researching anomalous electroweak sphaleron transition baryogenesis. Cueball: Cooool. Text on phone: A-n-o-m- [Caption below the panel:] My Hobby: Collecting really satisfying-sounding five-word technical phrases. Current favorites Transjugular intrahepatic portosystemic shunt placement Generalized autoregressive conditional heteroskedasticity model Unicellular diazotrophic cyanobacteria group A Anomalous electroweak sphaleron transition baryogenesis

Oily House Index

Oily House Index

https://www.xkcd.com/2327

https://www.explainxkcd.com/wiki/index.php/2327:_Oily_House_Index

[A line graph is shown. Above it is a rectangular frame with formulas inside. Most of the top part of the frame is removed and instead a heading is written over the missing section of the frame. The formula is written in three parts, with the first two parts having a division line with text written above and below.] Dimensional economic analysis New home price ($/sqft) / Oil price ($/BBL) = $/area / $/volume = Length [The graph has a labeled Y-axis with four ticks, which have values, and also the origin has a value. The X.axis is a time-line without label. There are five labeled ticks.] X-axis: 1980 1990 2000 2010 2020 Y-axis label: OHI (feet) Y-axis: 40 30 20 10 0 [Above the line graph there is a caption:] Oily House Index: How deep you could fill the average new home if you converted its mortgage to crude oil [The graph begins around 15 before 1980, then dips below 10, rises slowly until about 1988 when it rises sharply. It stays high but has several peaks, and one deep valley until 1999 when there is a very high peak, which then drops fast. A few more peaks, and then a decline to the lowest point in 2008, which is followed by a small peak, and then another drop. From there it stays low until 2015 when it rises quite fast and has one very high peak. It then drops of, until 2020 when there is a really sharp peak. Above the top of the peak is a dotted line extending to the top of the graph (i.e. the top of the Y-axis, not the top of the panel). Then it drops down but not very low as it reaches the present.] [There are six labels with arrows pointing from them to notable peaks and valleys along the graph. They are written both above and below the line. From left to right they are:] 1979 energy crisis Gulf War 1999 oil glut Oil and housing crashes partly cancel out 2010s oil glut OHI briefly became infinite as oil prices reached zero in 2020 [From 2005-2010 there is a dotted horizontal line that hits the valley at 2008. This is labeled with an arrow pointing to it:] Ceiling height [Below the line is a drawing of Cueball and Megan standing on the X-axis near 1990. Next to them is a label with an arrow pointing to them:] People (for scale)

In economics, an index is a statistical measure of change in a representative group of individual data points. Common indices include NASDAQ (a measure of a range of stock prices) and a consumer price index (a measure of retail prices) This chart demonstrates an invented index, the "Oily House Index", which measures a ratio of oil price to average house prices, over time. The numerator is the average price of a new home (presumably in the US), in USD per square foot ($/sqft). It does not specify what kind of home, or where. One available metric is the average price per square foot of floor space in new single-family houses in the United States which was $118.91 in 2019. The caption refers to converting the mortgage of the new house (that is, how much the purchaser borrowed, which could be zero), while the definition simply refers to the new home price (the total value). It is not clear which of these two is used in the chart. The denominator is the price of oil in USD per barrel ($/BBL). This is also not well defined, although the chart's caption suggests that it is based on crude oil. There are many different indices for different blends of oil in different locations, such as West Texas Intermediate , which is a crude oil commonly used as a global oil benchmark. (Others include Brent and Dubai Crude). The WTI price fluctuated around $55-60 throughout 2019. A barrel is a standard unit of oil volume, defined as 42 U.S. gallons (roughly 5.615 cubic feet or 0.16 cubic metres). The comic then applies dimensional analysis to this index: dividing $/sqft by $/bbl yields a result whose dimension is a linear measurement, which can be called length. 1 barrel is 42 gallons, a gallon is 231 cubic inches, and a cubic foot is 12 3 =728 cubic inches, so a barrel is approximately 5.6146 cubic feet and a cubic foot is approximately 0.1781 barrel. The average price per square foot of a new single-family dwelling in the USA in 2019 was about $119/square foot, while the price of oil in mid 2019 was about $60/BBL or $10.7/cubic foot. Dividing $119/square foot by $10.7/cubic foot gives approximately 11.1 foot. This is slightly lower than the value shown on the chart of around 15. The chart's caption then interprets that length as the depth that a new home could be filled with the crude oil that could be purchased with its price. For scale Cueball and Megan has been drawn, and the ceiling height of a typical house has been indicated, showing that only in time with deep crisis will the oil not fill the house. It's also not exactly clear where the extra oil should go after a multi-storey house has been filled; on the top floor, you could just take off the roof and let the oil pile up (perhaps after building some retaining walls), but on the lower floors, there's already oil above the ceiling. The index is high when house prices are high and oil prices are low (such as during the 1999 oil glut), and low when house prices are low and oil prices are high (such as during the 1979 energy crisis). See details about the chart below. The title text, "We're underwater on our mortgage thanks to the low price of water", is a pun. A mortgage on a property is considered to be "underwater" when the value of the mortgage exceeds the value of the property. This is bad for both the owner (who owes more money than the property is worth) and the bank (who now have a loan which is not fully secured against a default: if the property owner defaults, the bank will lose money in selling the property)- though obviously far worse for the owner. The title text is hinting at an alternative index based on the ratio of house price to the price of water instead of oil. At the 2019 rate of $118.91/ft² and a rough average water price of $0.0015/gallon , a house would have to be filled with water to a depth of 1060 ft for the house cost to match the water cost. If the price of water fell or the house cost per square foot rose, then the index would rise, causing the house to be even deeper in water (following the metaphor of the index as filling the house with physical water). This situation could arise even if the property value remained high, although Randall may be humorously suggesting that the increase in the index would literally flood the property with water, which would then damage it, obviously decreasing its value. (If the index continues to be computed on average house prices, then this single event would not materially impact the index as a whole.) In What If #11 "Droppings" , Randall commented that "unit cancellation is weird" after making a similar calculation about fuel efficiency -- the European convention of presenting fuel mileage as "liters per 100 kilometers" represents an area (volume/distance), which can be physically interpreted as the cross-sectional area of a tube of gasoline with the total volume of fuel burned stretched out over the length of the journey. 1979 energy crisis In the wake of the Iranian Revolution , global oil supply reduced by only 4%, but caused widespread panic and a huge increase in oil price. Gulf War The Gulf War (August 1990 - Feb 1991) was the invasion of Iraq by the US, which decreased oil supplies and caused a spike in prices. 1999 oil glut In early 1999, Iraq increased its oil production, while the Asian Financial Crisis reduced demand. Prices briefly fell to as low as $16. [1] Ceiling height Reinforcing the connection with the metaphorical house filled with oil, "ceiling height" here is shown at somewhere just below 10 feet. The standard ceiling height in US homes is 9 feet for ground floor, and 8 feet on higher floors. [2] Only twice has the height been below ceiling height, during the 1979 energy crisis, and in the beginning of the financial crisis of 2007-2008. Oil and housing crashes partly cancel out As a result of the financial crisis of 2007-2008 , oil prices crashed from $147/BBL in July 2008 to $30 in December 2008. Meanwhile, falling house prices , which had partially triggered the financial crisis, continued to slump across the US, with the Case-Shiller home price index reporting its largest ever price drop in December 2008. Since both oil price and house prices were falling, the effect of dividing one by the other means that the index didn't change significantly, remaining around 8-15 feet. 2010s oil glut In 2014-16 there was a serious surplus of crude oil , partially caused by increasing shale oil from the US and Canada, a slowdown in demand from China, and increasing fuel efficiency and use of renewable energy. Prices dropped from $125/BBL from 2012 to below $30 in January 2016. By October 2018, prices had recovered to $85/BBL. ] OHI briefly became infinite as oil prices reached zero in 2020 In April 2020, the coronavirus pandemic dramatically reduced vehicle and air transport, crashing oil demand. Oil futures actually went to zero , and even below, several times: oil producers paying consumers to take their oil, to avoid the costs of storing it. Dividing anything by zero officially has no defined result, but in many thought experiments yields infinity, hence the "infinite oily house index". The graph should actually wrap around to the negative axis at this point. [A line graph is shown. Above it is a rectangular frame with formulas inside. Most of the top part of the frame is removed and instead a heading is written over the missing section of the frame. The formula is written in three parts, with the first two parts having a division line with text written above and below.] Dimensional economic analysis New home price ($/sqft) / Oil price ($/BBL) = $/area / $/volume = Length [The graph has a labeled Y-axis with four ticks, which have values, and also the origin has a value. The X.axis is a time-line without label. There are five labeled ticks.] X-axis: 1980 1990 2000 2010 2020 Y-axis label: OHI (feet) Y-axis: 40 30 20 10 0 [Above the line graph there is a caption:] Oily House Index: How deep you could fill the average new home if you converted its mortgage to crude oil [The graph begins around 15 before 1980, then dips below 10, rises slowly until about 1988 when it rises sharply. It stays high but has several peaks, and one deep valley until 1999 when there is a very high peak, which then drops fast. A few more peaks, and then a decline to the lowest point in 2008, which is followed by a small peak, and then another drop. From there it stays low until 2015 when it rises quite fast and has one very high peak. It then drops of, until 2020 when there is a really sharp peak. Above the top of the peak is a dotted line extending to the top of the graph (i.e. the top of the Y-axis, not the top of the panel). Then it drops down but not very low as it reaches the present.] [There are six labels with arrows pointing from them to notable peaks and valleys along the graph. They are written both above and below the line. From left to right they are:] 1979 energy crisis Gulf War 1999 oil glut Oil and housing crashes partly cancel out 2010s oil glut OHI briefly became infinite as oil prices reached zero in 2020 [From 2005-2010 there is a dotted horizontal line that hits the valley at 2008. This is labeled with an arrow pointing to it:] Ceiling height [Below the line is a drawing of Cueball and Megan standing on the X-axis near 1990. Next to them is a label with an arrow pointing to them:] People (for scale)

Space Basketball

Space Basketball

https://www.xkcd.com/2328

https://www.explainxkcd.com/wiki/index.php/2328:_Space_Basketball

[Cueball, holding a basketball in front of him in both hands, is looking up at the basketball hoop in front of him. The hoop is on a standard board, but at the foot of the rod holding the hoop, there seems to be growing grass up, indicating it is outside.] Cueball: Okay, here are the rules: Cueball: I have to make 30 shots in a row before a meteor falls through the hoop. Cueball: I'm a 30% free throw shooter so the odds are actually pretty even. Cueball: Ready...Go! [Caption below panel:] My hobby: playing basketball against space

This is another comic in Randall 's My Hobby series , released during the same week as his last hobby comic, 2326: Five Word Jargon . Randall wishes to play basketball against outer space , hence the title Space Basketball . (His previous attempt at creating a " New Sports System " for multiplayer socially-distant basketball was not very successful.) His goal is to make thirty baskets in a row before the universe puts a meteor through his hoop. It should be noted that while may be technically correct to call the falling space object in this case a "meteor", when it hits the ground moments later it would be known as a meteorite . See also Terminology section below. See also 1405: Meteor , for what Randall's thoughts are on this. Randall estimates that his success rate at free-throw shooting is approximately 30%. Therefore, the chances of Cueball making 30 shots in a row is 0.3 30 , or about 1 in five quadrillion (2×10 −16 ); for comparison, there are approximately 150 quadrillion seconds remaining before the Sun engulfs the earth (5 billion years), so if Randall has a chute set up under the basket and enough basketballs to sustain a constant high rate of shooting, he has "decent" odds of achieving his goal before the Sun burns out. But really, Randall has comparably rapid learning at this task, whereas asteroids have extreme persistence far beyond Randall's life, so when he says the odds are comparable he is abstractly weighing his unique skillset against that of small stellar bodies. Still, the lifetime odds of being killed by a meteorite have been estimated at 1 in 75,000 or 600,000 or 700,000 [1] . These calculations are usually based on the probability of being alive at a time when a huge impact kills billions of people. Randall just uses the chance of one meteorite shot on Earth hitting this hoop (hoop-area divided by Earth-area = 3.2×10 −16 ) which is in the same range as 0.3 30 . Actual meteorite fall statistics report an average of 1.2 meteorites per year hitting the European continent which suggests that the average probability of Cueball winning after each shot attempt is about equivalent to a meteorite passing through the hoop over the period of 10 hours. Therefore Cueball has a better chance of winning than the universe "on the short term" if he makes more than 840 free-shot attempts per year for the rest of his life. The expected time for the universe to actually "complete" the challenge would be in the range of 8 billion years, the same magnitude to the current age of the universe and longer than the estimated remaining lifetime of the solar system . In the title text, Randall assumes that he would get better at free throwing shooting with practice in his lifetime ("the short term"). Some of the world's best basketball players have free-throw percentages over 90%, and even professional players with reputations of being "poor" free-throw shooters (e.g. Shaquille O'Neal) are above 50%. If Randall can improve his percentage to 50%, his odds of sinking thirty baskets in a row improve to "nearly" one-in-a-billion, while a member of the elite 50–40–90 club would have a probability better than four percent of making thirty free-throws in a row. Some specialists have achieved much higher success rates, with the record for most consecutive baskets being held by Tom Amberry with 2,750. The NBA regular season record is 97 free throws in a row, set by Micheal Williams in 1993 (during the 1992–93 and 1993 94 seasons). However, he acknowledges that in "the long term" (the life of the universe, or at least the Earth), the Earth will be hit by very many meteorites; even though it is more likely that Randall will make his thirty free-throws before a meteor passes through his basket, he does not possess the cosmic lifespan [ citation needed ] required to surmount the odds against him and actually have a good probability to witness either event. A piece of space debris falling through the atmosphere is a meteor . A piece of space debris that makes it all the way to the surface of the Earth (or any planet) is a meteorite . Most meteors burn up completely and do not become meteorites. The concept of a meteor passing through a basketball hoop, ten feet or less from hitting the ground, is so uncommonly discussed that the terminology could be a matter of some debate. Unless it is very large, a meteor this close to the ground will have slowed to terminal velocity and will no longer be burning up [ citation needed ] ; it will therefore not be incandescing like a conventional meteor, and it is certain that it will become an actual meteorite within just a moment. (Any meteor still incandescing within 10 feet of the ground, on the other hand, would presumably destroy both the basketball hoop and any nearby observer, meaning that poor Cueball, if still shooting, would lose the game in a much bigger way.) Many scientifically-aware people have the habit of correcting "meteor" to "meteorite," so it may be safest to use the latter term among nerds other than Randall, or you could out-nerd them by pedantically pointing out a reason to still call it a meteor. [Cueball, holding a basketball in front of him in both hands, is looking up at the basketball hoop in front of him. The hoop is on a standard board, but at the foot of the rod holding the hoop, there seems to be growing grass up, indicating it is outside.] Cueball: Okay, here are the rules: Cueball: I have to make 30 shots in a row before a meteor falls through the hoop. Cueball: I'm a 30% free throw shooter so the odds are actually pretty even. Cueball: Ready...Go! [Caption below panel:] My hobby: playing basketball against space

Universal Rating Scale

Universal Rating Scale

https://www.xkcd.com/2329

https://www.explainxkcd.com/wiki/index.php/2329:_Universal_Rating_Scale

[Caption above the frame:] Universal Rating Scale [A vertical scale, with 45 gradations, labelled. These are the grades:] 0 1 Strongly Disagree F [star] ☆ Extinct Tall 2 G Critical [frowny face] ☹ 3 endangered [two stars] ☆☆ PG Disagree VG 4 Grande 5 PG-13 [neutral face] 😐 6 T for Teen 7 [three stars] ☆☆☆ Agree Venti 8 Least Concern [smiley face] ☺ A Strongly Agree Category 5 EF-5 NC-17 UNC AA [four stars] ☆☆☆☆ A+ S AAA 10 10.0 11

In this comic, Randall has blended many traditional rating scales to create a "universal rating scale". Unfortunately, the mixing of these scales creates a scale that is impossible to use. Only a subset of the values of each rating scale is included, further weakening its claim as a "universal" scale. The result is much like the attempt to create a "universal standard" in 927: Standards . Alternatively, it can be perceived as a way of comparing the different scales, for instance to answer a question like "Is it worse to get a 2 or an F?" Scale of zero to ten (but with an 11, because people often add that to exaggerate - see up to eleven about the meme) 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11. The number 9 is omitted, possibly because seven ate nine (789) or because nine is the neglected number . Competitive scores , such as for artistic gymnastics' Code of Points , (ordinarily from 0.0 to a perfect 10.0 ) 10.0 Likert scale strongly disagree, disagree, agree, strongly agree (often there is a "neither agree nor disagree" value in the middle, but it is not strictly required) School grades (there are also B, C, D, and others with + or -) F, A+ S - Schools in Japan may use the S grading , which is said to stand for "superior" , implying “even better than A.” The expression S is also used in daily life, generally perceived as an S in s pecial or s uper, here unrelated to the academic grading system. For example, the most expensive seat in a theater (e.g. a balcony seat) may be called S-seki (lit. “S seat”) in Japanese, while the second most expensive seat may be called A-seki . Many video games also use S grading, and some (such as Beat Saber and Dance Dance Revolution) use SS, SSS, and even more S's as ranks above that (though these are not shown in the webcomic). A possibly related expression is “Super S” as in Sailor Moon SuperS . Star rating 1 star, 2 stars, 3 stars, 4 stars, frequently used to rate restaurants, films etc. 5 star is omitted, probably due to Randall's opinion that items with 5 stars tend to only have had one rater and aren't trustworthy . Conservation status (this is only a subset of the nine groups in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species) extinct, critical (probably critical ly endangered ), endangered, least concern According to the title text, "extinct in the wild" is a half-step below "critical", presumably above "G". Starbucks brand beverage sizes (there is also short and trenta) tall, grande, venti MPAA age-appropriate film ratings took effect November 1, 1968 with G, M (now PG), R (not shown in comic) and X (now NC-17) G, PG (as of February 11, 1972, replaced GP ), PG-13 ( introduced July 1, 1984), NC-17 (introduced September 1990, replaced X ) ESRB age-appropriate ratings for video games (there is also EC for early childhood, E for everyone, E10+ for Everyone 10+, M for Mature, and AO for Adults Only) T for teen Happiness emojis (alternately, the Wong–Baker Faces Pain Rating Scale ) Frowny face (☹, U+2639), neutral face (😐, U+1F610), smiley face (☺, U+263A). It is not totally clear which emoji each symbol is meant to refer to. The unhappy face could be Worried Face 😟, Anguished Face 😧, Frowning Face ☹️ (note the lack of eyebrows), Slightly Frowning Face 🙁 etc. Coin grades G, VG, UNC meaning good, very good, and uncirculated respectively Hurricane/cyclone strengths , Saffir–Simpson scale (ordinarily categorized from category 1 to category 5) Category 5 Tornado intensities , enhanced Fujita scale (ordinarily categorized from EF0 to EF5) EF-5 Credit (and other) ratings A, AA, AAA Credit rating agencies will rank businesses and governments based on their likely ability to pay back their creditors' interest ratings. The very highest are rated AAA, and then (in Standard & Poor's scheme) AA+, AA, AA-, A+, and so on. (Note that Randall's scale rates A+ as better than AA, indicating that it's the "A+" from school grades rather than the one from Standard & Poor's list.) This could also be a reference to battery sizes. This would imply that AAA is better than AA, which is not necessarily true, but funny to think about. Alternatively, this could be a reference to sports tier divisions; where AA and AAA basketball for example promote age and skill appropriate competition. The title text suggests that the scale as shown here is incomplete, by referencing further gradings that are not shown in the table. Critically endangered and Extinct in the wild are real conservation status categories recognised by the IUCN, although it's not clear what "Critically endangered/extinct in the wild" would mean - perhaps the "possibly extinct in the wild" designation, abbreviated CR(PEW). It would presumably fit on the table somewhere between "Extinct" and "Critical", although its ordering relative to "tall", "2" and "G" is unclear. The title text suggests that a score at this level had been graded on a curve , which bumped its rating up to "Venti", which is on the table, two steps below "Least concern". This would be an extraordinary example of such a curve, pushing the score from approximately 2/10 to almost 8/10. This could only happen if the exam was extremely difficult, meaning most results were significantly below 2/10. [Caption above the frame:] Universal Rating Scale [A vertical scale, with 45 gradations, labelled. These are the grades:] 0 1 Strongly Disagree F [star] ☆ Extinct Tall 2 G Critical [frowny face] ☹ 3 endangered [two stars] ☆☆ PG Disagree VG 4 Grande 5 PG-13 [neutral face] 😐 6 T for Teen 7 [three stars] ☆☆☆ Agree Venti 8 Least Concern [smiley face] ☺ A Strongly Agree Category 5 EF-5 NC-17 UNC AA [four stars] ☆☆☆☆ A+ S AAA 10 10.0 11

Acceptable Risk

Acceptable Risk

https://www.xkcd.com/2330

https://www.explainxkcd.com/wiki/index.php/2330:_Acceptable_Risk

[All of the panels depict the same two characters seen from a long distance, making them difficult to recognize. However, they appear to be Cueball (on the left) and Ponytail (on the right). They are each wearing a mask.] [Cueball and Ponytail talk to each other, standing at a distance:] Cueball: Okay. Based on the local virus prevalence, our careful quarantines, and the steps we've taken to reduce transmission risk, Cueball: I think it's okay for us to hang out. Ponytail: I agree. [Three small panels, vertically on top of each other] [Cueball and Ponytail get closer to each other.] [Cueball and Ponytail get still closer.] [Cueball and Ponytail standing near each other:] Cueball: Hi. Ponytail: Hi. [A normal sized panel, with Cueball and Ponytail standing near each other. They are yelling, with their arms raised:] Cueball: Is this social interaction good enough that it's worth risking our lives and the lives of others?! Ponytail: I don't know! Cueball: AAAAA! Ponytail: AAAAAA! [Cueball and Ponytail stand much farther apart.] Cueball: Healthy socializing was hard enough before the pandemic. Ponytail: Let's just try again in 2021.

This comic is another comic in a series of comics related to the COVID-19 pandemic . This comic shows Cueball and Ponytail , who are nervous to spend time in close proximity while the coronavirus is still widespread, and while lockdown procedures are still in effect across the world. Despite taking many precautions, such as wearing masks and maintaining physical separation, they still fear the effects of the virus, and attempt to weigh the value of actually seeing each other in-person versus potentially catching the virus. This is a dilemma faced by many, as the United States enters the fourth month since stay at home orders began. Cueball and Ponytail are particularly affected because they are known to overthink everyday decisions and interactions (in spite of their protestation to the contrary in the title text), as seen in e.g. 1445: Efficiency . Moreover, Cueball is bad at social interactions , virus or no virus, as pointed in the last panel. The comic title "Acceptable Risk" is formally used in risk assessments as a risk level that so low that it is comparable with other daily life risks. Typically, Acceptable Risk is defined as the probability of death being about one in a million. Cueball implicitly makes a risk assessment where he takes into account local virus prevalence and steps to reduce transmission risk coming to the conclusion that the risk to "hang out" is an acceptable risk. During the meeting however he becomes aware that for a good risk control strategy he also has to consider the trade-off between the benefits of taking the risk of "social interaction" over the benefits of completely avoiding the risk. Additionally, the numerous precautions that Cueball and Ponytail have taken to reduce risk (wearing masks, meeting in a featureless empty field with no other people, maintaining a safe distance) likely make the social interaction much less enjoyable, and thus perhaps not worth it at all. Cueball and Ponytail figure that it is extremely hard to measure the benefits of social interaction for them, and thus decide that for now complete avoidance is the better risk control strategy. Their screaming actually increases the risk of the interaction; this is why Japan recently banned screaming on amusement park rides (you read that right) , and why many jurisdictions are levying particular restrictions on singing even when gatherings are permitted. [All of the panels depict the same two characters seen from a long distance, making them difficult to recognize. However, they appear to be Cueball (on the left) and Ponytail (on the right). They are each wearing a mask.] [Cueball and Ponytail talk to each other, standing at a distance:] Cueball: Okay. Based on the local virus prevalence, our careful quarantines, and the steps we've taken to reduce transmission risk, Cueball: I think it's okay for us to hang out. Ponytail: I agree. [Three small panels, vertically on top of each other] [Cueball and Ponytail get closer to each other.] [Cueball and Ponytail get still closer.] [Cueball and Ponytail standing near each other:] Cueball: Hi. Ponytail: Hi. [A normal sized panel, with Cueball and Ponytail standing near each other. They are yelling, with their arms raised:] Cueball: Is this social interaction good enough that it's worth risking our lives and the lives of others?! Ponytail: I don't know! Cueball: AAAAA! Ponytail: AAAAAA! [Cueball and Ponytail stand much farther apart.] Cueball: Healthy socializing was hard enough before the pandemic. Ponytail: Let's just try again in 2021.

Hamster Ball 2

Hamster Ball 2

https://www.xkcd.com/2331

https://www.explainxkcd.com/wiki/index.php/2331:_Hamster_Ball_2

[Cueball is inside a transparent human-sized sphere, evidently "rolling" forward. Ahead of him is White Hat, wearing a mask.] Cueball: They laughed at me, all those years ago, when I got this human-sized hamster ball. [Frameless panel with just Cueball rolling forward, with his hand in a fist.] Cueball: But who's laughing now?!? [Cueball and White Hat have stopped. White Hat is pointing into the distance.] White Hat: Sounds like the same people. White Hat: See? There's some of them over there. [Cueball turns around to roll backwards while White Hat stands next to him still.] Cueball: Yeah, neighborhood kids. Cueball: At least they've stopped trying to roll me into soccer goals. Cueball: No, here they come. Cueball: Run!

This comic is another in a series of comics related to the COVID-19 pandemic . A hamster ball is a small, transparent sphere in which a hamster or other pet rodent can run around (reasonably) safely, without being in its cage. Cueball had previously obtained a " human-sized hamster ball " for himself. Cueball relates that, once upon a time, he was teased for this seemingly-frivolous pursuit, but he feels that now, in the midst of a worldwide coronavirus pandemic , having his own bubble to be inside is a smart move. He is contrasted to White Hat, who is wearing a facemask for protection. "Who's laughing now" is a common phrase that you know better than others who originally laughed at you, or that the "tides have turned" and you have a control over the situation. However, as White Hat notes, the same people who laughed at Cueball before are still laughing at him, for the same reasons as before: even though his hamster ball has some practical utility now (enforcing social distancing), it still looks ridiculous and is lots of fun to roll around. In the title text, Cueball says that he feels worst about being teased by "responsible, mask-wearing" teens, who treat the outside of his hamster ball as a potentially-contaminated surface (which it is, if it has previously been rolled around by ir responsible teens who might have contracted and spread the coronavirus) and disinfect it, taking care to avoid spraying the vents and thus not exposing Cueball's lungs to a hazardous chemical, before rolling him around. It's not clear why he doesn't like being rolled around by responsible teens; it could be that he vindictively wishes that they would catch the coronavirus from the outside of his hamster ball, thus proving that he was correct to use it, or it could be that his ego is injured by the fact that even responsible and otherwise well-mannered and socially-conscious teenagers (who are not likely to be particularly harmed themselves by COVID-19, but conscientiously follow guidance to reduce transmission and protect those who are at-risk) find his hamster ball so ridiculous that they have to have fun at his expense. As the title indicates, this is the second comic specifically devoted to hamster balls; the first was 152: Hamster Ball , in which Cueball wished for a genie to give him a human-sized hamster ball (and then had no other wishes he wished to wish). A human hamster ball also features prominently in 211: Hamster Ball Heist . [Cueball is inside a transparent human-sized sphere, evidently "rolling" forward. Ahead of him is White Hat, wearing a mask.] Cueball: They laughed at me, all those years ago, when I got this human-sized hamster ball. [Frameless panel with just Cueball rolling forward, with his hand in a fist.] Cueball: But who's laughing now?!? [Cueball and White Hat have stopped. White Hat is pointing into the distance.] White Hat: Sounds like the same people. White Hat: See? There's some of them over there. [Cueball turns around to roll backwards while White Hat stands next to him still.] Cueball: Yeah, neighborhood kids. Cueball: At least they've stopped trying to roll me into soccer goals. Cueball: No, here they come. Cueball: Run!

Cursed Chair

Cursed Chair

https://www.xkcd.com/2332

https://www.explainxkcd.com/wiki/index.php/2332:_Cursed_Chair

[Beret Guy and Cueball are talking.] Beret Guy: Remember how I bought my desk chair from that mysterious shop? Cueball: I think so? Beret Guy: Turns out the chair was cursed. [Beret Guy and Cueball are still talking. Beret Guy has his palms out.] Beret Guy: So I went back to return it, but the shop was gone! The door was boarded up! Cueball: I think most of the shops are closed because of coronavirus. [Beret Guy has his hands over his mouth in shock.] Beret Guy: Oh no! Beret Guy: The curse must have caused the pandemic! Cueball (off-panel): What. [Beret Guy starts running with a raised sword in a frameless panel. Cueball is next to him.] Beret Guy: If I destroy the chair, we can stop the virus! Cueball: What. [Beret Guy is chasing a floating desk chair. Cueball is watching.] Beret Guy: Die, plague-bringer! Desk chair: Hee hee I can not die Cueball: Maybe you should just shop at IKEA.

This comic is another in a series of comics related to the COVID-19 pandemic . Beret Guy informs Cueball that he purchased a cursed office chair from a mysterious shop. Cueball isn't sure if he remembers this happening, which is possibly because Beret Guy has previously stated that he makes a habit of purchasing daily necessities from such stores. Beret Guy then exclaims that the store he bought the chair from was gone when he went to return it, though given his buying preferences, he should perhaps not be so surprised. Cueball suggests that maybe the shop was simply closed due to the COVID-19 pandemic , as is the case for wide variety of non-cursed businesses. Beret Guy takes this as proof that the chair somehow caused the pandemic, a claim Cueball meets incredulously. In the final panel, Beret Guy is doing battle with the chair, which taunts him and claims to be immortal (“ I can not die ”). In fact, most chairs cannot die, because they are not alive. [ citation needed ] Cueball remarks that it would be simpler to shop at IKEA , a store famous for its minimalist flat-pack furniture, and which does not sell cursed items [ citation needed ] (although they do sell “ miniature Dyson spheres ”). The cursed chair and the boarded-up store are references to the stores that sell cursed items mentioned in 1772: Startup Opportunity . In that comic, the stores vanished without a trace. But the fact the door was boarded is much more likely due to the pandemic or other causes than the store mysteriously disappearing. Buying an item from a shop you never noticed before, bringing it home, discovering it is cursed, and trying to return it only to discover the shop isn’t there anymore is a popular trope. See The Little Shop That Wasn't There Yesterday . In the title text, the Siege Perilous is the empty seat at the Round Table in Arthurian legend, reserved by Merlin for the knight who would find the Holy Grail (who turns out to be Sir Galahad ) and fatal to anyone else who sits in it. Herman Miller is an American office furniture company that produced the Aeron chair , which is the basis for an artwork by Glenn Kaino called The Siege Perilous . Wirecutter is a website that evaluates and recommends consumer products. From the title text, it sounds like (in the xkcd universe) Wirecutter is used to encountering cursed products, [ citation needed ] so they didn’t even bother trying to sit in it to test the Siege Perilous’s perilousness (er, peril ) before they started fighting it—and emerged victorious, if it’s only nearly as immortal as it boasts. [Beret Guy and Cueball are talking.] Beret Guy: Remember how I bought my desk chair from that mysterious shop? Cueball: I think so? Beret Guy: Turns out the chair was cursed. [Beret Guy and Cueball are still talking. Beret Guy has his palms out.] Beret Guy: So I went back to return it, but the shop was gone! The door was boarded up! Cueball: I think most of the shops are closed because of coronavirus. [Beret Guy has his hands over his mouth in shock.] Beret Guy: Oh no! Beret Guy: The curse must have caused the pandemic! Cueball (off-panel): What. [Beret Guy starts running with a raised sword in a frameless panel. Cueball is next to him.] Beret Guy: If I destroy the chair, we can stop the virus! Cueball: What. [Beret Guy is chasing a floating desk chair. Cueball is watching.] Beret Guy: Die, plague-bringer! Desk chair: Hee hee I can not die Cueball: Maybe you should just shop at IKEA.

COVID Risk Chart

COVID Risk Chart

https://www.xkcd.com/2333

https://www.explainxkcd.com/wiki/index.php/2333:_COVID_Risk_Chart

[This comic is a graph plotting the safety risk of activities on the vertical axis and the risk of infection from COVID-19 on the horizontal axis. Lowest risks are in the upper left corner, and highest in the lower right. All activities are color coded green, yellow, orange, or red. A two way arrow labeled “non-COVID risk” points up and down to "high" and "low" labels on the left side of the graph. Another two way arrow labeled “COVID risk” points left and right to "high" and "low" labels on the top of the graph. From left to right and top to bottom:] Staying home & Video chats , Hanging out with friends in the park , Grocery shopping , Attending in-person classes , Singing in church Going for walks , Hanging out with friends on the beach , Grocery shopping while hungry , Attending online classes while sitting in class at a different school , Going to a restaurant Riding an electric scooter , Renting an electric scooter , Grocery shoplifting & Riding a single rental scooter with a stranger , Getting a dental cleaning & Going on a Tinder date , Going to a bar & Going to a party & Hosting a party & Going on a cruise Going down a waterslide , Going down a waterslide with a stranger , Getting in a stranger’s car , Getting a dental cleaning from a Tinder date , Opening a kissing booth at a COVID testing site Playing lawn darts , Climbing up a waterslide with a stranger , Getting in a stranger’s car uninvited , Doing skateboard tricks in a hospital , Doing skateboard tricks in a bar Doing skateboard tricks , Riding the conveyor belt through the TSA x-ray machine , Axe throwing contest , Racing a scooter through a hospital with a mask on & Racing a scooter through a hospital without a mask , Skateboarding into a mosh pit on a cruise ship Setting off fireworks in your car , Running and sliding headfirst into the pins at a bowling alley , Stealing a stranger’s car , Racing a scooter through a hospital with a mask on & Racing a scooter through a hospital without a mask [extends from previous row], Skateboarding into a mosh pit on a cruise ship & Getting a COVID test from a stranger at a crowded bar Bungee jumping while doing sword tricks , Going down a waterslide on an electric scooter , Setting off fireworks in a stranger’s car & Axe catching contest , Racing a scooter through a hospital with a mask over your eyes , Winning a test-tube-eating contest at a COVID testing lab

This comic is another in a series of comics related to the COVID-19 pandemic . This comic is a graph showing the risk of COVID-19 infection of numerous activities on the horizontal axis, while showing the other (i.e. safety) risks of the activity on the vertical axis. The activities are also color coded green, yellow, orange, or red, presumably indicating whether engaging in them is a good idea. All the activities are green in the upper left corner (no COVID-19 danger and no other dangers), but change to yellow, orange, and red as you go right or down. This presentation and color progression is similar to a common presentation of a risk matrix . One-dimensional charts showing the COVID-19 risk of common activities were popular at the time of this comic, when businesses and schools were re-opening after the first wave of COVID-19. The top of the graph contains activities that people are likely to engage in during the pandemic, beginning (from left to right) with staying at home, hanging out with friends at the park, grocery shopping, attending in-person classes, and singing in church. The first few activities are common and not very dangerous (colored green and yellow), but the last two come with significant risks of infection due to COVID-19 (they are colored orange and red). Lower on the graph the activities become more and more dangerous (though these dangers are not related to COVID-19, i.e.: they are non-covid risks) and then non-sensical, a trend often seen in xkcd comics. Some activities are grouped together, being variations of the same thing (such as going down a waterslide, going down a waterslide with a stranger, and going down a waterside on an electric scooter). The last row contains extremely dangerous activities such as (from left to right, or from low COVID-19 danger to high) bungee jumping while doing sword tricks, going down a waterslide on an electric scooter, (participating in an) axe catching contest, racing a scooter through a hospital with a mask over your eyes, and winning a test tube -eating contest at a COVID testing lab. All these activities are likely to result in undesirable outcomes. [ citation needed ] Part of the humor comes from the increasing ridiculousness of the "red" activities, some of which are unlikely combinations or escalations of other less-risky activities (e.g. renting an electric scooter is a "green" activity, but riding that scooter with a stranger carries more risk, and then still more from racing that scooter through a hospital, with or without a mask). This comic strip is similar in presentation to 2282: Coronavirus Worries . The title text suggests a ticket to "the" kissing booth as a prize. Presumably, the prize is for the test-tube eating contest, and the booth is the kissing booth mentioned in the comic, "a kissing booth at a COVID testing site". A kissing booth is a kind of sideshow sometimes seen at carnivals, where members of the public can pay a small fee to kiss someone, usually an attractive woman. Winning a ticket would normally be positively received. However, since kissing is a very high risk activity for COVID-19 transmission, it would now be perceived as a kind of punishment. Moreover, if the ticket was the prize for the test-tube eating contest then not only would the winner already likely have infected themselves with COVID-19, but they are likely to have mouth injuries from eating glass, making the kiss even riskier. The lowest-risk category of activities has very low COVID risk and also very low non-COVID risk. Staying home The lowest-risk activity of all, as long as the home itself is safe, and your family members do not have COVID-19. Video chats Video chatting carries a slightly higher non-COVID risk than simply staying at home, because you might get into an upsetting argument or accidentally expose something embarrassing. As long as the person you're chatting with is not within your personal space, the risk of catching COVID from them is still zero. Hanging out with friends in the park Physically interacting with others creates an increased risk COVID transmission, but the major risk of transmission seems to come from sharing enclosed spaces, not the outdoors, and as long as everyone keeps to themselves, they can still safely enjoy the social interaction (as long as they aren't prone to overthinking everyday decisions ). Going for walks Going for walks carries very little COVID risk as long as you stay by yourself. It is slightly more dangerous than staying home though, as you might fall or hurt yourself in some way. Hanging out with friends on the beach This has a similar COVID risk as hanging out with friends in the park, but has slightly more safety concerns due to possible unpleasant encounters with crabs, jellyfish, and other ocean-going animals as well as the risks posed by extended UV exposure. There are also negligible risks of tsunamis, shark attacks, and encounters with other rare and deadly animals. Riding an electric scooter Electric scooters are scooters powered by electricity. They have increased in popularity recently, representing a form of lightweight transportation. If done by oneself, riding one has essentially no risk of coronavirus, but it is relatively easy to injure oneself when riding an electric scooter. Electric scooters have previously been mentioned in E Scooters . Renting an electric scooter This has a slightly higher COVID risk than riding your own scooter, as a previous renter could have left traces of the virus on the handle bars. In terms of general safety, it is the equivalent of riding your own scooter. Going down a waterslide Waterslides are common attractions at water parks and even some community pools. They are simply slides made faster by running water down them. They are not extremely dangerous, so long as the rider can swim or stand in the pool of water at the end of the slide, though it is definitely possible to injure oneself on one, both reasons perhaps contributing to it being the most dangerous of the "green" activities. As long as the water is properly filtered, any handrails are sanitized between riders, and riders waiting in line and in the pool are appropriately separated, there is little risk of catching COVID. The medium-risk category of activities has medium COVID risk and also medium non-COVID risk. Grocery shopping Going shopping for groceries involves entering a building in which others are present, including many workers who are present for hours-long shifts. The risk of catching COVID can be reduced by wearing face masks, barriers between staff areas and customer areas, and limiting customer densities. Grocery shopping while hungry Shopping for groceries while hungry does not carry any greater risk of catching COVID, but this shows a slightly increased non-COVID risk because people who go shopping while hungry tend to buy foods that are more expensive and less healthy. (Be advised that a study that popularized this "common sense" result has been retracted due to academic misconduct by its author, Brian Wansink .) Grocery shoplifting Shoplifting is taking goods without paying, so this activity is stealing groceries. It would expose you to the same amount of COVID risk as regular grocery shopping, but would additionally subject you to the risk of arrest and/or physical retaliation. And even if not detected, self-inflicted risks may result from your possibly apocryphal chosen method of subterfuge. While this activity is not very risky and is colored yellow, it is probably not a good idea. Riding a single rental scooter with a stranger This is a bad idea, as most rental scooters are designed for only one person. It would also expose you to a stranger, who might have COVID. The safety concern of riding with two people on a one-person scooter is not reflected in the comic. Going down a waterslide with a stranger This carries the same risks as going down a waterslide by yourself (as long as the waterslide is designed for two people), but exposes you to a stranger who could have COVID. Getting in a stranger’s car This can potentially be risky because driving is dangerous, and because murders have occurred in the past when people hitchhike. Getting into a stranger’s car would also expose you COVID, if they are carrying the virus. A car is a confined space, which is generally considered particularly bad from a COVID perspective. Playing lawn darts This activity poses little risk of COVID-19 transmission, as this game is usually played outdoors and players generally do not have to be close to play, so standard outdoor precautions can be taken. Lawn darts can pose a moderate risk of personal injury if played unwisely, which is why they have been banned in their original metal-tipped form in the United States and Canada. Climbing up a waterslide with a stranger This activity poses similar risk of COVID-19 transmission as the "going down a waterslide with a stranger" activity, but there is higher non-COVID risk because waterslides are meant to "go down", and going against the normal flow of water (or without ensuring that nobody else is sliding down) may result in injury. Getting in a stranger’s car uninvited This has similar risk as the normal "getting in a stranger's car", but there is higher risk of getting in a car uninvited , as you may be considered a hijacker or trying to steal the car, and thus the stranger may physically attack you. Doing skateboard tricks Performing tricks on a skateboard, especially if well away from other people, carries little risk of COVID-19 transmission, but carries a moderate risk of personal injury, especially when a manoeuvre does not go as intended and/or the rider unintentionally comes off the board to collide with the ground and/or obstacles. Riding a conveyor belt through the TSA x-ray machine This has relatively low risk of COVID infection, assuming the conveyor X-ray machine belt is sanitized; however, this is generally not legal or lawful and may get you in trouble with the TSA and other authorities, and you might get cancer because of the exposure to X-rays. Axe throwing contest Under normal circumstances, attending an axe throwing contest is a fairly risky endeavor, as an improperly thrown axe has a tendency to rebound off the target and could hit you (whether you are throwing or merely spectating). The global pandemic adds an additional layer of risk, as if you are engaged in an axe throwing contest you most are most likely in close contact with other people increasing your risk of catching COVID-19. This is where things start getting serious. This category of activities has a higher COVID risk and same for the non-COVID risk. Attending in-person classes While there is low risk to injure oneself in class, most schools have closed at the beginning of the COVID pandemic to prevent the virus from spreading through close proximity attendees. Some schools have switched to online classes, while others have reopened and reduced the number of students per classroom. The risk of transmission would then be greater when attending in-person than online class. Attending online classes while in class at a different school Continuing on the previous activity, participating to classes in both modes at the same time wouldn't augment risks associated with COVID, but could cause mental exhaustion or similar stress-related symptoms. If you are not properly paying attention to a class you should be attending, or have inexplicably gone to a classroom that you have no reason to be in, there are further risks that you will fall foul of a teacher's or school's authority. Getting a dental cleaning Superficial dental work by a trained practitioner is not particularly risky under normal circumstances, but COVID precautions in most sitations (keeping at a distance, using face coverings) aren't compatible with the requirements of one person leaning in close to another person's open mouth and prodding into it with various tools. Going on a Tinder date Meeting a stranger is very much the point of a Tinder date. Even if the intimacy only extends to drinks and/or a meal it is difficult to 'socially distance' while still being sociable. The meet-up intention, by one or both parties, might be expected to be even less distancing. As well as COVID risks from well-intentioned encounters, there are very basic risks (on the night or consequentially) to health and happiness that cannot be entirely ruled out. Getting a dental cleaning from a Tinder date It seems that the COVID risk from combining the above two activities do not significantly compound, but: the low likelyhood that an almost-random stranger is trained in dental hygiene adds to the non-COVID risks to impromptu dentistry; if they are qualified, they are unlikely to have turned up properly equipped; if they arrive equipped, without pre-arrangement, that may also be worrying. Doing skateboard tricks in a hospital Skateboarding in a confined indoor setting, or in rooms furnished with beds and equipment should be significantly more risky than in a skatepark or other typical venue. Possibly the immediacy of healthcare professionals and supplies makes the outcomes of any injuries less problematic. However, your exertions in the proximity of likely sources for the COVID pathogen is a significant issue in itself. Racing a scooter through a hospital with a mask on Your skateboard tricks may have been not particularly mobile, like Feet Stomps and other in-situ board-flips. If you're on a scooter ( foot- , electric- or combustion-powered ) that is deliberately traveling fast then you're living more dangerously. But at least you're wearing a mask, to slightly reduce the accompanying contagion risks... Racing a scooter through a hospital without a mask ...unless you aren't? Setting off fireworks in your car A car is an extremely confined space, and most fireworks need a lot of space once lit. It's not obvious if you are supposed to be in the car yourself, but there is at least risk of damaging the vehicle. Running and sliding headfirst into the pins at a bowling alley Intending to impact a bunch of 1.5kg pins, with your head doing the job normally done with a ~7kg ball, is not considered particularly risk-free. Being in a (normally) communal recreational facility, there may also be chances of contact with surfaces previously shed-upon by the exertions of a COVID-infected person. Stealing a stranger’s car This is illegal, may involve risk of physical confrontation and do you really want to get into that driver's seat without thoroughly disinfecting it first? This is where things start getting really serious and even somewhat absurd. This category of activities has the highest COVID risk and the highest non-COVID risk. Singing in church Being in a public gathering place such as a church is a significant exposure risk for COVID. While singing is normally harmless, in a church singing is often done without masks and in a group, further increasing exposure in this case. There have been cases of outbreaks traced to choir practices/performances , which motivated bans on singing in churches. However, the same article mentions that a fluid mechanics expert studied the airflows from singing and various instruments and came to the conclusion that "singing is quite safe". (Certain instruments were another matter.) N.b., the outbreaks traced to the four choirs mentioned in the article were all prior to widespread practice of prevention measures. Going to a restaurant Restaurants are another place where traffic and exposure to COVID is high, as well as being a confined space. Other accidents, such as fires, falls, or choking add to the non-COVID risk. Going to a bar Similarly to restaurants, bars are also a place where COVID-19 spreads often. Bars can be more crowded than restaurants, with people sitting or eating in closer proximity. However, since the customers are more likely to be drunk and to get into a fight, the non-COVID risk is increased. Even if not engaging in violence, people who are even slightly inebriated are more likely to ignore standard precautions like social distancing. Going to a party / Hosting a party Parties are a highly social activity which increases exposure to COVID. Hosting or attending a party carries similar COVID-related risk as both involve interactions with others, while accidents can occur at a party, contributing to the non-COVID risk. However, hosts may still have a slightly larger COVID-related risk as they are more likely to be touching objects or surfaces on which the virus is present as they tidy up during or after the party, and are likely in proximity of all the guests during the party. Going on a cruise Cruises have been a site where many people have contracted COVID , leading to the high COVID-related risk. However, there are other risks associated with cruises that are non-COVID related, such as the risk of the ship sinking, or other sicknesses, etc. Opening a kissing booth at a COVID testing site Opening a kissing booth at a COVID testing site is likely to attract others who may be sick with COVID (since they are likely at the testing site to be tested, or to have been in proximity to someone who is), and kissing them greatly increases the risk of transmission. Opening a booth close to a testing site may also lead to controversy, adding to the non-COVID related risk. (A kissing booth is a place where one can kiss the person at the stand as a prize or in exchange for money). Doing skateboard tricks in a bar As mentioned before, bars are places where it is very likely to contract COVID. Doing skateboard tricks in such a confined space also leads to a very large risk of injury. Skateboarding in a mosh pit on a cruise ship Mosh pits are often very densely crowded with people, so the risk of transmission is huge. Also, doing skateboard tricks in such a crowded area means one could get trampled, knocked over, run into other people and/or things, etc. Additionally, doing these on a cruise ship heightens the risk, as mentioned above. Getting a COVID test from a stranger at a crowded bar As mentioned before, bars greatly increase the risk of contracting COVID, and getting a test from a stranger means the test itself carries many non-COVID related risks coming from a malicious or incompetent stranger. Testing for COVID-19 involves taking a sample of mucus, saliva, or blood; any of these sampling apparatus may potentially be contaminated with COVID or other diseases if they are being improperly re-used. Bungee jumping while doing sword tricks While bungee jumping is an activity that is often not performed in a crowded area, meaning that it is difficult to contract COVID while doing so, the act of bungee jumping while doing sword tricks could lead to a host of injuries. Going down a waterslide on an electric scooter As mentioned before, if the waterslide is not used by many people, riding it is not likely to cause COVID. However, since waterslides contain water and electric scooters contain batteries (they don't mix well, safety-wise), many injuries may result. Also, some areas of the waterslide {i.e. tunnels) could result in you flying out of the electric scooter and injuring yourself further. Setting off fireworks in a stranger's car A car is a confined space, and so the risk of contracting COVID is higher. Setting off fireworks in cars also will cause many injuries to everyone in the car, and more injuries in reactions from the driver and/or other angry passengers. Axe catching contest The proximity to others during a contest means a higher risk of contracting COVID. As for the axe catching part, injuries are likely to occur from attempting to catch flying axes, especially if the catcher is inexperienced. Racing a scooter through a hospital with a mask over your eyes A hospital is a place where COVID patients often stay, leading to a higher risk of contracting the disease. Having a mask over one's eyes would do nothing to help reduce the risk. Riding a scooter while effectively blindfolded in an area that has many obstructions like a hospital can lead to many injuries. Winning a test-tube-eating contest at a COVID testing lab Eating many test tubes which potentially contain samples containing COVID will almost definitely lead to one contracting the disease, and eating glass will lead to numerous internal injuries which will then easily lead to death. The title text proclaims that "First prize is a free ticket to the kissing booth!" further increasing the risk. [This comic is a graph plotting the safety risk of activities on the vertical axis and the risk of infection from COVID-19 on the horizontal axis. Lowest risks are in the upper left corner, and highest in the lower right. All activities are color coded green, yellow, orange, or red. A two way arrow labeled “non-COVID risk” points up and down to "high" and "low" labels on the left side of the graph. Another two way arrow labeled “COVID risk” points left and right to "high" and "low" labels on the top of the graph. From left to right and top to bottom:] Staying home & Video chats , Hanging out with friends in the park , Grocery shopping , Attending in-person classes , Singing in church Going for walks , Hanging out with friends on the beach , Grocery shopping while hungry , Attending online classes while sitting in class at a different school , Going to a restaurant Riding an electric scooter , Renting an electric scooter , Grocery shoplifting & Riding a single rental scooter with a stranger , Getting a dental cleaning & Going on a Tinder date , Going to a bar & Going to a party & Hosting a party & Going on a cruise Going down a waterslide , Going down a waterslide with a stranger , Getting in a stranger’s car , Getting a dental cleaning from a Tinder date , Opening a kissing booth at a COVID testing site Playing lawn darts , Climbing up a waterslide with a stranger , Getting in a stranger’s car uninvited , Doing skateboard tricks in a hospital , Doing skateboard tricks in a bar Doing skateboard tricks , Riding the conveyor belt through the TSA x-ray machine , Axe throwing contest , Racing a scooter through a hospital with a mask on & Racing a scooter through a hospital without a mask , Skateboarding into a mosh pit on a cruise ship Setting off fireworks in your car , Running and sliding headfirst into the pins at a bowling alley , Stealing a stranger’s car , Racing a scooter through a hospital with a mask on & Racing a scooter through a hospital without a mask [extends from previous row], Skateboarding into a mosh pit on a cruise ship & Getting a COVID test from a stranger at a crowded bar Bungee jumping while doing sword tricks , Going down a waterslide on an electric scooter , Setting off fireworks in a stranger’s car & Axe catching contest , Racing a scooter through a hospital with a mask over your eyes , Winning a test-tube-eating contest at a COVID testing lab

Slide Trombone

Slide Trombone

https://www.xkcd.com/2334

https://www.explainxkcd.com/wiki/index.php/2334:_Slide_Trombone

[Megan walking along carrying a trombone.] Offpanel voice #1: Hey, her old trombone. Offpanel voice #2: Cool, I haven't seen that thing since the 90s. [Four quick shots of Megan moving the trombone's slide back and forth. It makes sound, but not like an ordinary trombone.] FX: Slide FX: Hisss FX: Slide FX: Hisss [Megan does something else with the trombone, and it shoots water at the offpanel observers.] FX: Pshhhhh Offpanel voice #1: AUGH! Offpanel voice #2: So that's where my Super Soaker went.

In this comic, Megan carries her "old" trombone , a brass musical instrument with a movable sliding piece used to change a musical note's pitch, which those offscreen apparently haven't caught sight of since the 90s (presumably the 1990s). These offscreen people don't suspect anything unusual of Megan's trombone until it turns out that it contains a water gun, which she uses to soak the other characters. It is unclear whether she has somehow hidden the water gun inside the trombone, has disassembled it to produce a hybrid trombone/Super Soaker device, or otherwise modified the trombone such that it can shoot water as a water gun would. In the second panel, she is priming the water gun by pumping air into it, following the sequence of pump actions used for the Super Soaker. During the first "slide" action, the user pulls the grip towards themselves, increasing pressure within the water reservoir of the gun. During the second "hiss" action, this grip is pushed away; a valve prevents air leaving the chamber, though a small amount usually leaks out. Part of the joke here is that a slide trombone also has a slide mechanism, held in a similar way as that of the Super Soaker, but which serves a completely different purpose. In the case of the trombone, when the slide is extended, the total length of tubing between the mouthpiece and the bell is extended, thereby lowering the pitch of the sound that is produced (there is, however, no comparable air chamber). This similarity between the two devices enables Megan to use the trombone's slide as if it were a Super Soaker's. In the third panel, she presses the trigger, causing the compressed air within the water reservoir to push water from it at high speed, hitting the off-screen targets. One cries out in surprise, while the other expresses the realization of what had happened to their lost Super Soaker (that Megan had taken it as an alteration to her trombone). In the title text, Megan asks those offscreen about the CPS 2000 , a water gun which, as is mentioned, was powerful but too powerful, causing injuries to those shot by it and allegedly leading to its discontinuation. Megan then, in connection with her previous question about the Super Soaker, asks to borrow a tuba, most probably to hide the CPS 2000 water gun inside. Her reasoning behind needing this tuba seems to be that the CPS 2000 is seemingly larger than the Super Soaker originally stored in Megan's trombone and thus would require a larger vessel (this use of the tuba may be cause for loss of friendship with an experienced player). The CPS 2000 referenced by Megan was developed primarily by Lonnie Johnson (inventor) and Bruce D'Andrade for Larami 's Super Soaker product line. The "CPS" within its name refers to the " Constant Pressure System " used in certain water guns (its technology can be seen in this patent by Bruce D'Andrade). In this system, a rubber bladder within the water gun is pressurized by the user's pumping action, which draws water from a reservoir and pushes it into the pressure chamber, filling the bladder like a balloon. Once the desired volume of water is stored within the toy, the water can be released by means of a spring-loaded trigger and valve system. Upon release, the rubber bladder pushes the water out of the pressure chamber and out of the front nozzle, hitting whatever targets the user desires it to. The "constant pressure" of the CPS's name refers to the fact that the bladder will exert the same pressure on the water throughout the shot, ensuring consistent power and range, as opposed to air pressure Super Soakers, whose power will die off during the shot as the pressurized air within the pressure chamber expands, expelling the water but reducing the pressure in the toy. The Super Soaker that Megan uses in this comic is also referenced in 220: Philosophy and 517: Marshmallow Gun . If the water gun featured in this comic is the same as that depicted in previous comics, it would likely be a Super Soaker 50 , the first widely available pressurized water gun. It could also be the less common but earlier model the Power Drencher or the later SS 50 Classic Series , Super Soaker S.E. , or the 20th anniversary SS 50 rerelease . [Megan walking along carrying a trombone.] Offpanel voice #1: Hey, her old trombone. Offpanel voice #2: Cool, I haven't seen that thing since the 90s. [Four quick shots of Megan moving the trombone's slide back and forth. It makes sound, but not like an ordinary trombone.] FX: Slide FX: Hisss FX: Slide FX: Hisss [Megan does something else with the trombone, and it shoots water at the offpanel observers.] FX: Pshhhhh Offpanel voice #1: AUGH! Offpanel voice #2: So that's where my Super Soaker went.

Photo Deposit

Photo Deposit

https://www.xkcd.com/2335

https://www.explainxkcd.com/wiki/index.php/2335:_Photo_Deposit

[Megan is holding a banknote up in one hand, while she is taking a picture of it with her smartphone held in the other hand. A starburst near the phone indicates the sound this makes. She is standing with her back to Cueball, who faces away from her. He is holding a banknote down by his side in one hand, while he is looking at his smartphone which he holds up in the other hand. From Cueball's phone there is a starburst from which a line goes up above him to indicate what is on the screen.] Megan's phone: Click Cueball's phone: Deposit accepted! [Caption below panel:] After a lucrative six hours for us, our bank removed the new feature in their app that let you deposit cash by taking a picture of it.

Some mobile banking apps allow users to deposit checks through the app, by photographing the check and entering the relevant information. The comic parodies this imagining a bank that allowed you to "deposit" banknotes via a mobile app, by taking photos of them. The caption implies that this attempt is predictably disastrous, as it's shut down within six hours. Checks are essentially documents instructing a bank to disburse funds from a given account to a specified recipient, hence electronic transfers make sense: the recipient's bank can transfer the image to the depositor's bank and the funds can be transferred between the two. The check could only be deposited by the recipient, and any attempt to deposit the check repeatedly would be refused (and potentially subject the recipient to legal action). By contrast, cash functions as a bearer instrument , where physical possession of the banknotes effectively constitutes possession of the funds. Hence, depositing cash electronically would make little sense, as the depositor would still have the notes (and therefore the money), and the bank would not. Such a transaction would enrich the depositor at the expense of the bank. The title text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. However, this would not solve the fundamental problem. Clients could still deposit all of their cash and retain ownership of it. And they could then exchange those bills for different ones and deposit the new bills, repeating the process indefinitely (which explains Cueball's comment about "a lucrative six hours"). It is possible that Megan and Cueball are deliberately depositing the same bills to each of their accounts, given their close proximity. The only way such a system could work is if every entity that accepted cash payments or deposits operated from a common database, functioning in real-time, which kept track of each transaction, and disallowed any further use of that specific bill. This would have the ultimate impact of making cash virtually useless, as once every bill had been spent once, all future transactions would need to be electronic (unless there were a system in place to physically distribute the appropriate bills to the appropriate people, which would defeat the entire point). Such a system is essentially the basis for cryptocurrency , which uses a crowd-sourced system to track the movement of money. But such a system would require virtually universal acceptance in a given country, and could not be implemented by a single bank. In addition, the system would be highly vulnerable to counterfeiting . Common anti-counterfeiting measures include using distinctive materials and fine details, both of which are difficult to duplicate well enough to fool a human. Smartphone cameras, on the other hand, can't distinguish texture and may not have sufficient resolution to make out that level of detail. Counterfeiters could produce and deposit an almost unlimited number of bills, then destroy them, leaving little evidence of their crime. As a result, this system would be inherently unworkable, and the party that would suffer from it would be the bank that implemented it in the first place. Which makes it realistic that, if a bank were to implement such a scheme, they'd very quickly realize their error and put an end to it. This is why the bank took down this system. [Megan is holding a banknote up in one hand, while she is taking a picture of it with her smartphone held in the other hand. A starburst near the phone indicates the sound this makes. She is standing with her back to Cueball, who faces away from her. He is holding a banknote down by his side in one hand, while he is looking at his smartphone which he holds up in the other hand. From Cueball's phone there is a starburst from which a line goes up above him to indicate what is on the screen.] Megan's phone: Click Cueball's phone: Deposit accepted! [Caption below panel:] After a lucrative six hours for us, our bank removed the new feature in their app that let you deposit cash by taking a picture of it.

Campfire Habitable Zone

Campfire Habitable Zone

https://www.xkcd.com/2336

https://www.explainxkcd.com/wiki/index.php/2336:_Campfire_Habitable_Zone

[A campfire is in the middle of the panel in a white area with two areas shaded green to the left and right of the fire. There are also two white areas outside of these green areas. Ponytail is sitting normally on the ground to the left of the fire, with her body fully inside the left green area. She is facing the fire and is holding a stick in both hands. The stick has a marshmallow on the tip and she is holding it over the top of the flames of the fire. Cueball is sitting to the right near the fire, only half inside the green are. He is sitting sideways leaning away from the fire, holding one hand to his head, while his other hand seems to be ready to support him as he is leaning further away from the fire. The arm closest to the fire and his head seems to be very hot as three small smoke-like lines rises from Cueball. Megan is crouching to the right of Cueball, far from the fire outside the right green area. She is supporting herself on one knee and one foot. She is also holding a stick in both hands with a marshmallow on it. She is holding the stick inside the green area to the right of Cueball far from the fire. Four small lines above and below indicates that she is waving the stick up and down. The camp fire is built up of several logs on top of each other, with big flames above it, with smaller flames hanging loose in the air above the main flames. A small dead tree is to the far left and small rocks/stones lie along the ground all the way from left to right interspersed with grass tufts. Below the scene there is a label from which two curved arrows point to the two green areas.] Label: Habitable zone [Caption below panel:] Astronomers define the Campfire Habitable Zone as the region where you're far enough not to be burned but close enough to roast marshmallows.

This comic plays on the concept of the astronomic "habitable zone" applied at the scale of people sitting around a campfire. The habitable zone of a star is the range of distances in which a planet might support liquid water, and hence life in the only form that we currently know of (as an allusion to the "not too hot, not too cold, but just right " of the related children's story , the habitable zone is also commonly known as the "Goldilocks zone"). If the planet is too close to the star, then the amount of stellar radiation would be too great, causing the water to boil; too far from the star, and the planet doesn't have enough radiation, causing the water to freeze (although for life to actually exist, the planet itself must also have the right mass in order to maintain a life-compatible atmosphere and meet other such requirements). For our Sun, the habitable zone is estimated to range from about 0.38 to 10 astronomical units, where 1 astronomical unit is the distance from the Sun to the Earth. Marshmallow toasting is a popular camping activity in which people place a marshmallow (a soft, sugary blob made of gelatin and covered in corn starch) on a stick and over/near a fire. As the marshmallow cooks, the inside becomes gooey while the outside becomes crispy (perhaps slightly charred and maybe even burned, depending on the toaster's preference), making it tastier via caramelization and the Maillard reaction . In the context of the campfire, a similar "habitable zone" is posited by Randall to exist: a zone which is close enough to the fire such that the person can comfortably toast marshmallows, presumably on a stick of reasonable length (the ones in the comic seem to be about 1.5 times an arm's normal reach), yet far enough such that the person is not uncomfortably hot or even burned by either direct contact with the flames or by exposure to the radiant heat of the fire. To demonstrate this hypothesis (with the habitable zones marked in green), Cueball is shown sitting outside the right habitable zone on the side of the fire. Even though he is able to toast his marshmallows on the fire due to his being close to it, he will have and is having part of his body scorched, as he is too close (fires can get really hot ). Megan, also on the right, is well outside the habitable zone on the side away from the fire. Although not burned, the marshmallow on the stick she is waving will presumably not toast due to its being too far from the campfire. Ponytail, on the other hand, has found and is enjoying the medium between the plights of both Cueball and Megan by sitting entirely within her (the left) habitable zone, thereby both being close enough to the fire to be able to toast her marshmallows while also staying far enough away such that she will not be burned. The title text introduces the concept of tidal locking , in which one astronomical body synchronizes its rotation with its orbit around another such that one side always faces the other body (e.g. the case of Earth's moon, which always presents the same face to the Earth). The joke here is that if a marshmallow became tidally locked to the fire, then one side would become more and more cooked, perhaps burnt, while the other side never became toasted at all. This also may allude to the instance in which a marshmallow has begun melting more than you realized and dripped down so far that it no longer responds to your rotation of the roasting stick (the solution to which is to cut your losses and pull the marshmallow out immediately, before it drops into the fire pit). [A campfire is in the middle of the panel in a white area with two areas shaded green to the left and right of the fire. There are also two white areas outside of these green areas. Ponytail is sitting normally on the ground to the left of the fire, with her body fully inside the left green area. She is facing the fire and is holding a stick in both hands. The stick has a marshmallow on the tip and she is holding it over the top of the flames of the fire. Cueball is sitting to the right near the fire, only half inside the green are. He is sitting sideways leaning away from the fire, holding one hand to his head, while his other hand seems to be ready to support him as he is leaning further away from the fire. The arm closest to the fire and his head seems to be very hot as three small smoke-like lines rises from Cueball. Megan is crouching to the right of Cueball, far from the fire outside the right green area. She is supporting herself on one knee and one foot. She is also holding a stick in both hands with a marshmallow on it. She is holding the stick inside the green area to the right of Cueball far from the fire. Four small lines above and below indicates that she is waving the stick up and down. The camp fire is built up of several logs on top of each other, with big flames above it, with smaller flames hanging loose in the air above the main flames. A small dead tree is to the far left and small rocks/stones lie along the ground all the way from left to right interspersed with grass tufts. Below the scene there is a label from which two curved arrows point to the two green areas.] Label: Habitable zone [Caption below panel:] Astronomers define the Campfire Habitable Zone as the region where you're far enough not to be burned but close enough to roast marshmallows.

Asterisk Corrections

Asterisk Corrections

https://www.xkcd.com/2337

https://www.explainxkcd.com/wiki/index.php/2337:_Asterisk_Corrections

[A screenshot of a text messaging app.] Other user: Do you have any weekend plans? User of this device: I'm gonna ride a horse on the beach at dawn *Eat *3AM *Couch *Pizza [Caption below the panel:] I like how we can do corrections in text chat by appending words with asterisks and our brains just figure out where they go.

In text messages, asterisks are commonly used to denote a correction of some error in an earlier text. Asterisk corrections typically specify the corrected words, but do not explicitly mark the words that should be replaced. The words that should be replaced are simply the words in the message that make sense to be replaced by the correction, often the ones that are the closest by spelling or meaning to the correction. In this comic, the messenger ( Randall ) corrects four such inaccuracies. The message, if the corrections were to be taken in order, might read "I'm gonna eat 3 AM on the couch at pizza." The typical reader should be sharp enough to know that it should read "I'm gonna eat a pizza on the couch at 3 AM.", replacing the ones that are closest by function in the sentence. Randall finds this remarkable. Taken one at a time, it appears the reader would have the following sentences in their head: I'm gonna ride a horse on the beach at dawn (original sentence - sounds adventurous and sporty) I'm gonna eat a horse on the beach at dawn (replacing the action - a figure of speech?) I'm gonna eat a horse on the beach at 3AM (replacing the time - occultish?) I'm gonna eat a horse on the couch at 3AM (replacing the location - lazily occultish, or worse?) I'm gonna eat a pizza on the couch at 3AM (replacing the food - not too odd, but very slobbish) Human brains can process these corrections automatically because the syntax of most English sentences are as follows: Subject — Verb — Object — Manner — Place — Time Other languages have different word orders but generally have the same six categories. The messenger's original sentence can be parsed as follows: I (subject) — am gonna ride (verb) — a horse (object) — (no manner) — on the beach (place) — at dawn (time) . Notice that the four corrections fall into four different categories in this structure, so there is only one sensible replacement: "Couch" and "pizza" are both nouns so they could theoretically be subjects, but asterisk corrections must replace an existing part of the sentence satisfactorily, so the "'m" part of the verb prevents these third-person nouns from being parsed as the subject. Theoretically one could also swap "couch" and "pizza" around, giving "eat a couch on the pizza", but this makes much less practical sense than "eat a pizza on the couch". That said, in xkcd's fictional universe there is nothing to stop the character from eating a couch on a pizza. In the title text, Randall says that he likes to make it as difficult as possible for his text recipient to guess where his correction should be, and uses the following sentence and correction: "I'd love to meet up, maybe in a few days? Next week is looking pretty empty." *witchcraft The trick here is trying to figure out which word(s) should be replaced by "witchcraft". Broadly speaking, "witchcraft" could serve as an activity, but no words for activities exist in the original sentence, leaving the reader to guess at the intent. Possible solutions suggested in the comments are: "I'd love to witchcraft , maybe in a few days? Next week is looking pretty empty." "I'd love to meet up, witchcraft in a few days? Next week is looking pretty empty." "I'd love to meet up, maybe witchcraft a few days? Next week is looking pretty empty." (These three examples verbed "witchcraft" to mean "perform witchcraft".) "I'd love to meet up, maybe in witchcraft days? Next week is looking pretty empty." "I'd love to meet up, maybe in a few days? Witchcraft week is looking pretty empty." ( Witchcraft week is an event in Bargota, Spain. It usually occurs in July, the month in which this comic strip was released, although this year's event in particular was canceled due to COVID-19 -- which would indeed make it pretty empty.) "I'd love to meet up, maybe in a few days? Next witchcraft is looking pretty empty." Of course, none of these solutions would be evident as correct to the recipient of the message, until Randall sends further corrections. One absurdity in the main comic panel is that, after all four corrections has been parsed, the meaning of the resulting sentence has no connection with the original sentence whatsoever. However, asterisk corrections are generally used to correct typing mistakes, not to completely change the meaning of the original message. This raises suspicion as to why the messenger wrote the original sentence in the first place. Perhaps Randall does want to make the comic as difficult for his readers to parse as possible while making the point that asterisk corrections are usually quite intuitive to understand. [A screenshot of a text messaging app.] Other user: Do you have any weekend plans? User of this device: I'm gonna ride a horse on the beach at dawn *Eat *3AM *Couch *Pizza [Caption below the panel:] I like how we can do corrections in text chat by appending words with asterisks and our brains just figure out where they go.

Faraday Tour

Faraday Tour

https://www.xkcd.com/2338

https://www.explainxkcd.com/wiki/index.php/2338:_Faraday_Tour

[Close-up on Hairy] Hairy: Hey there superfans, welcome to the livecast! [Hairy walks toward an opening in a large building] Hairy: Got a real treat for you today: a tour of the world's largest Faraday cage! Hairy: C'mon, let's check it- [Two panels of a "loading" spinner on a black background] [Hairy exits the building] Hairy: -was so cool! Wow!! Hairy: Thanks for coming along, and don't forget to smash that like button!

This comic is another in a series of comics related to the COVID-19 pandemic . Hairy , addressing an unseen camera (possibly the reader's POV) welcomes viewers to a livestream broadcast - that he calls/brands as a 'Livecast' - walking through "the world's largest Faraday cage ." A Faraday cage blocks electromagnetic transmission into and out of the cage area. Attempting to broadcast a walk through such a cage with any medium that uses radio waves would (theoretically, at least) cause the transmitter's signal to drop out completely, resulting in the loading wheel shown in panels three and four. Faraday cages do not necessarily have to be dark inside, as this one appears to be (they typically block longer wavelengths than those of visible light, which consists of electromagnetic waves). However, the darkness visually aligns with the concept of communications blackout , which is what Hairy's viewers experience while Hairy is in the cage. The darkness could be taken as a metaphor for depending so heavily on electronic connectivity for one's view of the world that anything not directly connected is conceived as unobservable. (Alternatively, the light switch could be inside the cage.) The Faraday cage that Hairy is visiting may also be an anechoic chamber for testing radio equipment, which would be completely lined with radiation-absorbent material , not just an open-air cage, to ensure that the measurements inside are of the highest quality. There's no particular reason that it would have to have the lights off for his tour (in fact, it would be better to have the lights on so that he could see the features inside), [ citation needed ] but some anechoic chambers have been used for sensory deprivation experiments , in which participants are shut inside in total darkness and quiet. "Smash that like (or subscribe, etc.) button" is a typical command given by YouTubers to watchers, asking to publicly "like" the video or subscribe to their channel if they enjoyed it, ultimately to boost the creator's popularity. Developers want lots of views, likes, and subscribes because YouTube pays artists (e.g. $1 per 1000 views). The title text refers to COVID-19 pandemic of 2020. The joke is that, as they don't get cell service in the cage, the owners would be unaware of global events. This implies for comedic effect that the owners and workers solely live inside the Faraday cage, continuing the theme of treating connectivity as the only way to acquire information. They would still be able to receive news if they ever step outside to welcome visitors, or have print media delivered, but their choice to unconventionally isolate themselves might reflect their general attitudes to the world outside and it is also implied that Hairy is one of the rare few outsiders they have pre-agreed to allow to visit, or one of the few people who would think to ask for and plan a tour during a pandemic. Randall has referenced Faraday cages for comedic effect in the past. See 1142: Coverage . [Close-up on Hairy] Hairy: Hey there superfans, welcome to the livecast! [Hairy walks toward an opening in a large building] Hairy: Got a real treat for you today: a tour of the world's largest Faraday cage! Hairy: C'mon, let's check it- [Two panels of a "loading" spinner on a black background] [Hairy exits the building] Hairy: -was so cool! Wow!! Hairy: Thanks for coming along, and don't forget to smash that like button!

Pods vs Bubbles

Pods vs Bubbles

https://www.xkcd.com/2339

https://www.explainxkcd.com/wiki/index.php/2339:_Pods_vs_Bubbles

[Cueball is walking to the right with Megan. He has his index finger raised dramatically.] Cueball: I refuse to bubble with anyone who calls it a "pod" and not a "bubble". [Caption below the panel]: This is probably my opinion that would have sounded the most incoherent to me a year ago.

This comic is another in a series of comics related to the COVID-19 pandemic . During the 2020 COVID-19 pandemic , various degrees of household self-isolation were often asked of people, depending on location, once it became understood that there was a virus spreading through contact/proximity vectors. As the initial surge of cases appeared to decline, in places where such drastic restrictions had been implemented and seemingly had prevented ever higher infection rates, many regions decreased the strictness of these measures. For instance, permitting any two households (neither having signs of symptoms) to meet with each other and only each other , or allowing one person in a multi-occupancy residence to invite just one other person to reassociate with. Further relaxation of rules may have occurred since, with the caveat that even one case of COVID-19 discovered in such a co-isolating group of people should be considered a risk factor to every other member (however the local jurisdiction deals with that). A common term for the larger social unit, not to overlap with any other expanded social unit, is a 'bubble', perhaps to imply that you can only have membership of one bounded bubble at a time (unlike an Euler diagram ). The term ‘build your bubble’ was coined by Dr Ingham (University of Otago, New Zealand) as a way of encouraging people with disabilities to create safe ‘bubbles’ with care givers during lockdown.  Another common term is 'pod', representing the closed nature of a pod. There is probably as much variation across the world about what podding or bubbling practically means as there is between any two instances of those podded vs. those bubbled. Some sports leagues have resumed play in these structures, with the media using the bubble terminology , both in the United States and across the wider world , as players and commentators alike resume some degree even of international competition (so long as they follow the 'bubble' rules ). Despite the semantic inconsequentialities of the difference, here Cueball clearly expresses a personal preference that he would probably not like being kept in an enforced social situation with someone who uses the other term. Randall realizes that, despite his tendencies towards strong opinions on semantics, this particular point is one he would have been highly unlikely to say a year ago, and probably would not even have understood what it meant, because he could not have foreseen the COVID-19 pandemic and its widespread impact. Cueball was shown using a literal bubble (a hamster ball ) in 2331: Hamster Ball 2 , but evidently got tired of being rolled around by the neighborhood kids. The title text refers to travel restrictions. Many countries have placed limitations on its citizens' travel, particularly in and out of that country. Canada has mandated 14-day self-isolation on anyone who has returned from out-of-country, and has strictly limited any attempts to leave the country, with the United States being specifically noted as a high-risk tourism destination. Randall jokes that such measures are only 99% meant as COVID-19 precautions, with the remaining 1% being due to the authorities sharing Randall's semantic opinions. [Cueball is walking to the right with Megan. He has his index finger raised dramatically.] Cueball: I refuse to bubble with anyone who calls it a "pod" and not a "bubble". [Caption below the panel]: This is probably my opinion that would have sounded the most incoherent to me a year ago.

Cosmologist Genres

Cosmologist Genres

https://www.xkcd.com/2340

https://www.explainxkcd.com/wiki/index.php/2340:_Cosmologist_Genres

A cosmologist is someone who studies the universe; cosmology is a branch of astronomy. When describing the composition of stars in astronomical terms, metals are all the elements heavier than helium . This definition of metal is significantly broader than the one used outside astronomy . Likewise, this chart of musical genres describes everything "heavier" than pop as metal. The standard conception of elemental metals is a subset of the astronomical conception of metals; likewise, here the musical genre metal is presented as a subset of the genres cosmologists consider metal. Randall may have decided to portray pop music in a similar way to the elements helium and hydrogen as a reference to the " pop test ", the test for hydrogen as a product of a chemical reaction. Cosmologists also study the history and future of the universe, and the title text refers to the Big Bang . At roughly 10 -32 seconds after the Big Bang, the inflationary epoch ended, causing a large number of quarks, anti-quarks , and gluons to come into existence. In inflationary cosmology , this point is considered to be the end of the Big Bang. Randall jokingly refers to it as "post-" because nearly the entire history of the universe is after this instant. This is a reference to types of music with "post-" in their names, e.g. post-rock , post-punk , post-metal .

Scientist Tech Help

Scientist Tech Help

https://www.xkcd.com/2341

https://www.explainxkcd.com/wiki/index.php/2341:_Scientist_Tech_Help

What tech people think scientists need help with: [Cueball, Ponytail, and Megan are facing a second Cueball and Hairbun. Ponytail is gesturing with her hand out. The second Cueball has his finger raised.] Ponytail: Please–our data, it's too complex! Can your magical machine minds unearth the patterns that lie within? Cueball 2: We shall marshal our finest algorithms! What scientists actually need: [The two Cueballs, Ponytail, Megan, and Hairbun are in the same position as before. The second Cueball no longer has his finger raised.] Ponytail: For a few weeks in June, the lab was infested by wasps, so we had to take pictures of the equipment through the window. Ponytail: How do you get graphs from a Polaroid photo into Excel?

In this comic, Randall pokes fun at stereotypes of scientists that "tech people" hold. In the first panel Randall, presents an idealized view of the tasks of tech people. A group of scientists have run their experiments and compiled their data, but find that the data is simply too complicated for humans, even advanced scientists such as themselves; the tech people resolve in heroic statements to decipher the data with their most advanced algorithms. Large portions of machine learning and data science hinge around finding a pattern (either regression or classification) in a given data set, but the more common, real-world problem is in data cleaning and preparation. For the most part, the rest can be done with preexisting implementations. These types of tasks are those that tech people both expect to perform, and hope to expand upon. The second panel presents a different reality. The scientists are fully confident they can interpret the data on their own, provided they can access it, because the methods of recording their data are incredibly sub-par. Apparently wasps had infested the lab, and the scientists had to take photos of their equipment through the window. This created a much more fundamental problem of data format than normal (image vs spreadsheet, as opposed to something more normal like pixel-wise vs vertex-based segmentation). The joke is that the scientists' questions for their tech specialists are very mundane in nature; it presents not a chance to test and prove their machine learning systems, but a simple and tedious process of untangling digital paperwork. This is true in real life — experts' expertise is usually deep, but not broad, and helping them with issues outside their comfort zone is rarely glamorous. Polaroid is a brand of instant camera , though "Polaroid" is often used to refer to instant cameras in general. Excel is referring to Microsoft Excel , a spreadsheet management program. The title text refers to WebPlotDigitizer , a tool which may be used on visual displays of data such as graphs and charts in order to extract the underlying data. This tool would have the potential to solve the problem which the scientists have by extracting data from the images taken of the equipment. Randall acknowledges the usefulness of the tool, but also expresses some dislike that the tool was invented at all — someone must have had the original data to draw the graph, thus if they had made the data available then he wouldn't have to reverse engineer the plot. Other possibilities are that he simply feels that the tool is too powerful and leaving him less work to do, or that tools so trite and seemingly unnecessary prove so useful in the end. 2116: .NORM Normal File Format deals with nested file formats. What tech people think scientists need help with: [Cueball, Ponytail, and Megan are facing a second Cueball and Hairbun. Ponytail is gesturing with her hand out. The second Cueball has his finger raised.] Ponytail: Please–our data, it's too complex! Can your magical machine minds unearth the patterns that lie within? Cueball 2: We shall marshal our finest algorithms! What scientists actually need: [The two Cueballs, Ponytail, Megan, and Hairbun are in the same position as before. The second Cueball no longer has his finger raised.] Ponytail: For a few weeks in June, the lab was infested by wasps, so we had to take pictures of the equipment through the window. Ponytail: How do you get graphs from a Polaroid photo into Excel?

Exposure Notification

Exposure Notification

https://www.xkcd.com/2342

https://www.explainxkcd.com/wiki/index.php/2342:_Exposure_Notification

[Cueball standing, holding out his chiming smartphone to review alerts it has received.] Alert 1:43 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:38 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:36 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:31 PM Good news: You recently had close contact with someone who has not tested positive for COVID. [Caption below the panel:] No one likes my new COVID exposure notification app.

This comic is another in a series of comics related to the COVID-19 pandemic . During the coronavirus pandemic, many apps were developed to implement digital contact tracing , using proximity detection or location tracking to notify people who had been potentially exposed to COVID-19. People who know they are infected are encouraged to isolate, and it takes time to test and find out if somebody is infected; so most notifications are retrospective, telling the user about past potential exposures. In this comic, a different type of app has been developed. Instead of notifying someone if they have been exposed to someone with COVID-19, the app produces notifications if they have been exposed to someone who has not tested positive. (Perhaps it also notifies the user if they have been exposed to a person who has tested positive, but if this is the case, it hasn't happened to the user in question yet.) This is much less useful because most people one would typically encounter would either not be infected, or not be aware of their infection, so almost every interaction will generate a notification, annoying the user. Also, being exposed to someone who has not tested positive is not good news, because it is still possible that the person might have COVID-19; it is simply less bad than being exposed to someone who has tested positive, but still worse than not being exposed to anyone. Socially and psychologically, modest amounts of people being close to each other normally is a positive behavior. For a typical person, it could be considered a sad sign of our times if you needed an app to tell you whether you did right in social interactions and compliment you. (For socially awkward people , on the other hand, this could be a welcome development.) In the title text, Randall decides to give in to users requests, and add a mode giving the bad news that you have been exposed to COVID-19. Calling this dark mode is a play on dark referring to less desirable, as well as dark mode, a common user interface option. Dark mode is a common feature in apps which allows users the options to have a user interface that gives off less light. Alternatively, it may just be that the developer is completely misunderstanding the user's actual needs. This would be consistent with creating an app that alerts the way this one did in the first place. Randall has published similar "useless useful apps" in 937: TornadoGuard (a tornado-alert app that has lots of great features, except it doesn't actually alert the user about tornadoes) and 2236: Is it Christmas? (a web page that correctly identifies most days as "not Christmas", but then fails to identify Christmas Day as Christmas, for a >99% "accuracy"). A week after this comic was posted, a user of the Canadian COVID tracing app posted an article about a similar issue: notifications from non exposure . [Cueball standing, holding out his chiming smartphone to review alerts it has received.] Alert 1:43 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:38 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:36 PM Good news: You recently had close contact with someone who has not tested positive for COVID. Alert 1:31 PM Good news: You recently had close contact with someone who has not tested positive for COVID. [Caption below the panel:] No one likes my new COVID exposure notification app.

Mathematical Symbol Fight

Mathematical Symbol Fight

https://www.xkcd.com/2343

https://www.explainxkcd.com/wiki/index.php/2343:_Mathematical_Symbol_Fight

[A chart is shown with 30 different symbols arranged above a line with arrows in both ends and with 17 ticks between the arrow heads. The symbols are mostly in two rows, but the first two symbols from the left do not have another symbol above them, and towards the right there are a segment with three rows of symbols. Above the symbols there is a heading and a subheading. And beneath those there is a long arrow pointing right with a label above it.] Mathematical Symbols By how useful they would be in a fight More useful ℝ     ∅ > ∝ π + Ψ ~ ⇒ ⋅ Γ √ ∮ ∫ ⇀ θ ∞ ∪ ∈ ∀ ∂ ≠ # Δ ζ ℵ ρ → ⊥ –– [Below the double arrow line are eight characters that fight each other in groups of two by using some of the symbols shown above them as weapons. They have chosen symbols that are almost above them in the chart.] [Megan is awkwardly handling a giant "ℝ" holding it up against White Hat who is holding a "θ" (or "∅"?) with both hands, as a shield.] [Cueball is holding an "∈" in both hands, with its "tines" pointed towards Blondie, who is swatting at him with a "#".] [Ponytail is leaping at Danish, swinging a " ρ " like an axe, while Danish is leaning back and thrusting a "→" back at her.] [Black Hat is swinging a long "√" like a polearm at Hairy, who is holding a long "⎯" defensively.]

This comic imagines which mathematical symbols would be good in a fight if they were made corporeal in two (or three) dimensions. Generally, objects with longer reach and pointier ends wound up on the right ("more useful") side of the scale, and symbols with less reach and more curves wound towards the left ("less useful") side. A straight line is farthest to the "more dangerous" side; however, the straight line does not appear to be any thicker or thinner, or pointier, than any of the other lines that would make it more "useful" (It should be noted that this chart seems to fall afoul of what Eliezer Yudkowsky (who also wrote HPMoR) calls the intent to kill : that humans tend to define "winning a fight" and "useful" as causing some form of bodily harm on their opponent despite survival and purely defensive strategies being an equally valid goals.). Below the chart, with the symbols listed in order of usefulness, eight characters wield eight of the symbols. See the table below for the meaning of each symbol. The comic invokes surreal humour by suggesting that mathematical symbols could be handled as physical objects in the real world. Another component of the humor is the implication that it is useful to prepare to use mathematical symbols in a fight, even though mathematicians, who use mathematical symbols, usually do not conduct their debates violently (though some stories suggest that Hippasus was killed by his fellow Pythagoreans for his proof that irrational numbers exist), and even if they did, they wouldn't use large reproductions of their symbols as weapons. The title text refers to a Treble clef , which is not a mathematical symbol but rather a musical symbol . The note of concern in the text suggests musical symbols may be viewed in such fights as exotic or especially dangerous. See also the last entry in the table below. [A chart is shown with 30 different symbols arranged above a line with arrows in both ends and with 17 ticks between the arrow heads. The symbols are mostly in two rows, but the first two symbols from the left do not have another symbol above them, and towards the right there are a segment with three rows of symbols. Above the symbols there is a heading and a subheading. And beneath those there is a long arrow pointing right with a label above it.] Mathematical Symbols By how useful they would be in a fight More useful ℝ     ∅ > ∝ π + Ψ ~ ⇒ ⋅ Γ √ ∮ ∫ ⇀ θ ∞ ∪ ∈ ∀ ∂ ≠ # Δ ζ ℵ ρ → ⊥ –– [Below the double arrow line are eight characters that fight each other in groups of two by using some of the symbols shown above them as weapons. They have chosen symbols that are almost above them in the chart.] [Megan is awkwardly handling a giant "ℝ" holding it up against White Hat who is holding a "θ" (or "∅"?) with both hands, as a shield.] [Cueball is holding an "∈" in both hands, with its "tines" pointed towards Blondie, who is swatting at him with a "#".] [Ponytail is leaping at Danish, swinging a " ρ " like an axe, while Danish is leaning back and thrusting a "→" back at her.] [Black Hat is swinging a long "√" like a polearm at Hairy, who is holding a long "⎯" defensively.]

26-Second Pulse

26-Second Pulse

https://www.xkcd.com/2344

https://www.explainxkcd.com/wiki/index.php/2344:_26-Second_Pulse

[Science Girl is standing in the front of a whiteboard holding a pointer up towards the board. Ponytail, Hairy, and Megan are sitting at desks facing Science Girl.] Science Girl: When everything is still, seismometers pick up faint tremors we call seismic noise. Science Girl: Most of it is from ocean waves, cars, etc. But there's also a mysterious 26-second pulse. [Close up on Science Girl. She is holding a hand palm up towards the board behind her, showing a map with Africa in the center and some other continents at the edges of the view. A star is drawn within the country of Ghana, near the coastline.] Science Girl: We've triangulated the source to somewhere in the Gulf of Guinea. Science Girl: It comes and goes with the seasons, but it's been there since at least the 1980s. It's so regular we use it to sync up seismometers. [In a frame-less panel only Science Girl is shown, once again in profile. She has the board behind her and points the pointer towards the board.] Off-panel voice: What causes it? Science Girl: Not sure. The most popular theory is that storm-driven waves set up some kind of resonance with the coast. [Science Girl has leaned her stick on the board's tray. She has raised her clenched fists.] Science Girl: Another theory is that long ago, seismologists murdered a giant and buried the body at sea. Science Girl: Now we are haunted by the beating of its telltale heart! Science Girl: Could be either. Science Girl: Further research is needed.

In this comic strip, Science Girl is presenting her project on geology to her class mates, and is explaining some of the non-earthquake signals that seismometers detect. She describes a mysterious signal that repeats with a 26-second period . Scientists have exploited this signal to correct for clock drift in historic seismic records. Science Girl initially provides a plausible explanation (some kind of natural wave pattern on the coastline of the Gulf of Guinea , which is in fact the most common theory about this signal). However, she quickly takes a turn for the dramatic when she claims that it might be a giant, murdered by seismologists, whose heart still beats. This is a reference to Edgar Allan Poe's short story The Tell-Tale Heart , in which the main character murders a man and hides his corpse beneath the floorboards, and then hears (or believes he hears) his victim's heart continuing to beat; the noise eventually drives him to confess his guilt to visiting police officers. (The narrator of The Tell-Tale Heart never uses that phrase in the story; he calls it a hideous heart.) "The Tell-Tale Heart" was previously referenced in 740: The Tell-Tale Beat . Normal human hearts beat much more rapidly than once every 26 seconds, but large animals and hibernating animals may have much slower heart rates (which would include a giant at the bottom of the ocean [ citation needed ] ). The title text gives an alternate explanation for the seismic activity: volcanic activity , but Science Girl continues to believe in the giant story. In the last panel she references the common science meme that further research is needed, which has been mentioned several times in previous strips, including 2268: Further Research is Needed . A seismometer is a device for measuring vibrations in the earth's crust, and one is likely in the collection of Cueball from 2060: Hygrometer . [Science Girl is standing in the front of a whiteboard holding a pointer up towards the board. Ponytail, Hairy, and Megan are sitting at desks facing Science Girl.] Science Girl: When everything is still, seismometers pick up faint tremors we call seismic noise. Science Girl: Most of it is from ocean waves, cars, etc. But there's also a mysterious 26-second pulse. [Close up on Science Girl. She is holding a hand palm up towards the board behind her, showing a map with Africa in the center and some other continents at the edges of the view. A star is drawn within the country of Ghana, near the coastline.] Science Girl: We've triangulated the source to somewhere in the Gulf of Guinea. Science Girl: It comes and goes with the seasons, but it's been there since at least the 1980s. It's so regular we use it to sync up seismometers. [In a frame-less panel only Science Girl is shown, once again in profile. She has the board behind her and points the pointer towards the board.] Off-panel voice: What causes it? Science Girl: Not sure. The most popular theory is that storm-driven waves set up some kind of resonance with the coast. [Science Girl has leaned her stick on the board's tray. She has raised her clenched fists.] Science Girl: Another theory is that long ago, seismologists murdered a giant and buried the body at sea. Science Girl: Now we are haunted by the beating of its telltale heart! Science Girl: Could be either. Science Girl: Further research is needed.

Wish on a Shooting Star

Wish on a Shooting Star

https://www.xkcd.com/2345

https://www.explainxkcd.com/wiki/index.php/2345:_Wish_on_a_Shooting_Star

[A Venn diagram is shown:] [The left circle is labeled "Things people wish for" and contains:] Love Money Fame Health Power Luck Success [The right circle is labeled "Things shooting stars can cause" and contains:] Radio noise Dust and ionized gas in the upper atmosphere Infrasound Cool lights in the sky [The only item in the overlapping section is:] Revenge

This comic was published at the annual peak of the Perseids meteor shower . It is a common practice to make a wish when one sees a shooting star, in hopes that the wish comes true. This comic consists of a Venn diagram showing what things are commonly wished for upon seeing a shooting star, and what things the shooting star may cause. Shooting stars, as they are actually meteors, can only cause changes to physical phenomena, such as radio noise or the appearance of the sky as they burn up in the upper atmosphere. The only thing that is shared between the potential wish side of the diagram and the shooting star caused side is revenge. This would occur when a shooting star actually hits the planet, becoming a meteorite. This is frequently highly destructive, given the high speed of falling meteors. As such, it would be possible for the meteorite to hit something that someone for some reason or another wished revenge upon. However, given the massive surface area of the planet, the likelihood that someone's revenge would be "granted" by a meteorite would be very low (although not quite as low as dunking a meteorite through a basket ). The title text makes fun of this by detailing several incidents where a meteorite landed and caused damage. List of things that were damaged by meteorites (from title text): If there is a "message" to this comic strip, it could be similar to those of 1024: Error Code and 2247: Weird Hill : that we shouldn't bother wishing for things that shooting stars can't give us, but should instead take time away from our temporal concerns and just relax and appreciate their beauty. Or maybe the message is that, if you must wish on a shooting star, you should wish for revenge, because that's something that might come true. Of course, as the title text makes clear, meteorites don't really land according to our designs and schedules, and if you're close enough to a shooting star to see it, and you wish for it to avenge you, and it is big enough to hurt someone, you're probably at risk yourself. Meteorites were most recently mentioned in 2328: Space Basketball . Randall has discussed strange and "impossible" wishes in 1086: Eyelash Wish Log . [A Venn diagram is shown:] [The left circle is labeled "Things people wish for" and contains:] Love Money Fame Health Power Luck Success [The right circle is labeled "Things shooting stars can cause" and contains:] Radio noise Dust and ionized gas in the upper atmosphere Infrasound Cool lights in the sky [The only item in the overlapping section is:] Revenge

COVID Risk Comfort Zone

COVID Risk Comfort Zone

https://www.xkcd.com/2346

https://www.explainxkcd.com/wiki/index.php/2346:_COVID_Risk_Comfort_Zone

Ways to say no when someone tells you to do something outside your COVID risk comfort zone: [A comic with three panels is shown.] [The first panel is large. There are 2 Cueballs each wearing masks. Inside Cueball appears to be in a doorway that leads into a building. Outside Cueball is showing Inside Cueball a phone.] Label: Too Indirect Inside Cueball: You have to come inside. Outside Cueball: Ok, but... I've been trying to follow the science, and they're really emphasizing the transmission risk in enclosed spaces. I know you're wearing a mask, and I feel so awkward making a scene over a tiny risk. But I'm trying to keep my overall risk acceptably low, which means having simple rules so I don't overthink every minor decision. See, if you look at this spreadsheet- [Second panel, smaller. Only the Cueball outside is shown now.] Label: Direct Outside Cueball: I'm so sorry, but I'm avoiding shared indoor spaces unless it's an emergency. [Third panel, even smaller. Only the Cueball outside is shown.] Label: Too Direct Outside Cueball: I'm not setting foot in your haunted plague box.

This comic is another comic in a series of comics related to the COVID-19 pandemic . One of the major vectors for transmission of SARS-CoV-2 is in sharing an enclosed space with someone who is infected, especially someone who is asymptomatic and not aware of being infected. Wearing a face mask, as both "Inside Cueball" and "Outside Cueball" are, will dramatically reduce the rate of transmission, perhaps by a factor of 30 compared to the "baseline" of neither wearing a mask, but given the limited volume of air available, it is likely that sooner or later one of them will inhale enough air with enough virus-bearing droplets to risk catching the disease. This knowledge leads Outside Cueball to refuse Inside Cueball's invitation to visit indoors, but (in a recurring theme of xkcd ) leaves him feeling uncertain as to how he should refuse the invitation. The comic proceeds to depict a spectrum of options. The first option is overly technical to the extreme, to the point where Outside Cueball is effectively giving Inside Cueball an in-depth lesson on common health advice during the 2020 COVID-19 pandemic. Being overly technical is a common trope among xkcd comics -- in particular, Outside Cueball's fervent insistence that he made a spreadsheet so he doesn't "overthink every minor decision" is disproved by (a) the fact that he made a spreadsheet (cf. 1445: Efficiency ) and (b) the events of 2330: Acceptable Risk . The second option that is presented is the most reasonable of the three, being an expression of reasonable concern, and a polite refusal to enter. The last option is simplified to the extreme, and successfully insults the owner of the building while still expressing a desire to avoid coming inside. The title text appears to be a continuation of the last panel. In it, someone, presumably Cueball, compares themselves to a vampire, because folklore has it that vampires cannot enter a building without permission. However, the speaker has no interest in coming inside, despite any invitations that they may have, whereas vampires usually want to come inside to drain the occupants' blood. Some vampires will even take measures to trick an invitation out of a hesitant "host", which is something that would be unthinkable to Outside Cueball under the COVID circumstances. As a fourth option compromise between the second and third choices, Cueball could just flatly refuse: "No," or "No, thank you." We don't know the circumstances here (is Inside Cueball a friend of Outside Cueball, a shopkeeper, or just a passing acquaintance?), but clearly there's no urgent reason that Outside Cueball has to go inside, and so he doesn't owe Inside Cueball any explanation (nor any insults). Other comics mentioning "COVID-19 risk" include 2330: Acceptable Risk and 2333: COVID Risk Chart (which might itself be the spreadsheet made or used by Outside Cueball). Ways to say no when someone tells you to do something outside your COVID risk comfort zone: [A comic with three panels is shown.] [The first panel is large. There are 2 Cueballs each wearing masks. Inside Cueball appears to be in a doorway that leads into a building. Outside Cueball is showing Inside Cueball a phone.] Label: Too Indirect Inside Cueball: You have to come inside. Outside Cueball: Ok, but... I've been trying to follow the science, and they're really emphasizing the transmission risk in enclosed spaces. I know you're wearing a mask, and I feel so awkward making a scene over a tiny risk. But I'm trying to keep my overall risk acceptably low, which means having simple rules so I don't overthink every minor decision. See, if you look at this spreadsheet- [Second panel, smaller. Only the Cueball outside is shown now.] Label: Direct Outside Cueball: I'm so sorry, but I'm avoiding shared indoor spaces unless it's an emergency. [Third panel, even smaller. Only the Cueball outside is shown.] Label: Too Direct Outside Cueball: I'm not setting foot in your haunted plague box.

Dependency

Dependency

https://www.xkcd.com/2347

https://www.explainxkcd.com/wiki/index.php/2347:_Dependency

[A tower of blocks is shown. The upper half consists of many tiny blocks balanced on top of one another to form smaller towers, labeled:] All modern digital infrastructure [The blocks rest on larger blocks lower down in the image, finally on a single large block. This is balanced on top of a set of blocks on the left, and on the right, a single tiny block placed on its side. This one is labeled:] A project some random person in Nebraska has been thanklessly maintaining since 2003

Technology architecture is often illustrated by a stack diagram , in which higher levels of rectangles indicate components that are dependent on components in lower levels. This is analogous to a physical tower of blocks, in which higher blocks rest on lower blocks. The stack in this cartoon bears a striking resemblance to a physical block tower, suggesting the danger that the tower will lose its balance when a critical piece is removed, in this case a piece near the bottom, labeled as being maintained by a single semi-anonymous person located somewhere relatively unimportant doing it for their own unknown reasons without fame or acknowledgement. The concept of balance is not intended to be communicated by a stack diagram, making this a humorously absurd extension of a well-known diagram style. ImageMagick , mentioned in the title text, is a popular, standalone utility released in 1990 that is used for performing transformations between various graphics file formats, and various other transformations. While there are also numerous libraries and APIs for performing these tasks within larger programs, ImageMagick is so popular and easy to use that many programs use its API or just find it easier to shell out to ImageMagick to perform a necessary transformation. They therefore depend on ImageMagick, and would break if ImageMagick were to disappear. Taking code re-usability and modularization to its logical extreme has been a long-time tenet for programmers; programming began as a slow task on very memory-constrained systems, utilizing punch cards and days of delay waiting to discover a bug, so that reuse made things possible that otherwise wouldn't be. Once systems became small, fast, and able to hold a lot of data, the ability to provide higher and higher degrees of automation made reusable libraries a huge engine behind the development of technology. By outsourcing what would seem like basic functions, such as string manipulation, to other libraries, developers waste less time reinventing the wheel, so the philosophy goes (or as Beret Guy's business practices literally: 2140: Reinvent the Wheel ), and thus many tiny packages, many of which contained only one function, became popular dependencies. This was especially true in Unix and Linux, where an entire program is commonly used for one small task, and programs exist to tie others together into powerful shell scripts. Node.js (a platform for JavaScript) and Python are two modern ecosystems providing huge stashes of centralized libraries where developers of the world can come together to stand on the shoulders of all the small useful libraries they make for each other, to make new ones that are more and more powerful, and also more and more prone to sudden new unexpected bugs somewhere in the dependency chain. JavaScript was designed to be an easy to use front end scripting language, not a basic and core backend language as users of node.js's NPM package manager have made it be. While in theory, such a system may sound good for developers who would need to write and maintain fewer lines of code, systems which are highly optimized are also highly susceptible to rapid changes. For example, the famous left-pad incident in the NPM package manager left many major and minor web services which depended on it unable to build. A disgruntled developer unpublishing 11 lines of code was able to break everybody's build, because everyone was using it. In 2014, the Heartbleed bug revealed a significant portion of the internet was vulnerable to attack due to a bug in OpenSSL, a free and open-source library facilitating secure communication. One headline at the time demonstrated this comic in real life: "The Internet is Being Protected by Two Guys Named Steve" . The aforementioned Steves were overworked, underfunded, and largely unknown volunteers whose efforts nevertheless underpinned the security of major websites throughout the world. Randall provided a concise, helpful explanation of the bug in 1354: Heartbleed Explanation . The current model of libraries and open-source development (topics which Randall has addressed extensively in the past) relies heavily on the free and continued dedication of unpaid hobbyists. Though some major projects such as Linux may be able to garner enough attention to build an organization, many smaller projects, which are in turn reused by larger projects, may only be maintained by one person, either the founder or another who has taken the torch. Maintaining libraries requires both extensive knowledge of the library itself as well as any use cases and the broader community around it, which usually is suited for maintainers who have spent years at the task, and thus cannot be easily replaced. Thus, there are many abandoned projects on the internet as people move on to greener pastures. Far from the days of backwards compatibility, that's usually not a problem, unless a project happens to be far up the dependency chain, as illustrated, in which case there may be a crisis down the road for both the developers and the users down the chain. [A tower of blocks is shown. The upper half consists of many tiny blocks balanced on top of one another to form smaller towers, labeled:] All modern digital infrastructure [The blocks rest on larger blocks lower down in the image, finally on a single large block. This is balanced on top of a set of blocks on the left, and on the right, a single tiny block placed on its side. This one is labeled:] A project some random person in Nebraska has been thanklessly maintaining since 2003

Boat Puzzle

Boat Puzzle

https://www.xkcd.com/2348

https://www.explainxkcd.com/wiki/index.php/2348:_Boat_Puzzle

[Cueball and Ponytail are standing on the bank of a river. There is a boat in the river. A goat and wolf are also on the riverbank, and Ponytail is holding a cabbage.] Ponytail: I need to cross the river. I have a wolf, a goat, and a cabbage. Cueball: Hmm. [White Hat appears, accompanied by two wolves and pulling a wagon full of cabbages.] Cueball: OK, here's what- White Hat: Hi, I also need to cross. I have two wolves and 100 cabbages. [Black Hat arrives, surrounded by a cloud of flying creatures and carrying a jar of bugs under his arm. Beret Guy follows with another wolf and goat on leashes.] Black Hat: I have 50 cabbage moths and 2,000 boat-destroying termites. Beret Guy: I have a wolf that can operate a boat, and a goat that eats wolves. [The fourth panel is a zoomed-out shot, where everything but the sky appears black.] [A trolley speeds in, leaving a trail of dust in its wake. A person is standing on the front, and many ears are barely visible above the seats.] Cueball: Hang on, I need to make a spreadsheet. Trolley operator: Look out! Trolley operator: My wolf-filled trolley is out of control and can only be stopped by a cushion of cabbages!

This comic is a twist on an old riddle . In the original riddle, a person has to cross a river in a boat that can only hold them and one other object. They have a wolf, a goat, and a cabbage that they need to bring across with them, similar to the first panel. If the wolf is left alone with the goat, however, the wolf will eat the goat; and if the goat and cabbage are alone, the goat will eat the cabbage. (The problem can be solved in seven trips.) However, the comic quickly devolves into surrealism in the later panels as new characters show up, bringing deviations of the original "cabbage", "goat", and "wolf" that add extra layers of complexity to the riddle. White Hat brings extra wolves and cabbages. Black Hat , in his traditional classhole style, brings cabbage moths which will infest unsupervised cabbages with destructive larvae, and boat-destroying termites . How he intends to bring them across the river (or even if he wants to) is unknown, but it brings to mind the parable of The Scorpion and the Frog . Beret Guy arrives with a wolf who can operate a boat, who could perhaps serve as a second pilot to expedite the crossing, so long as he is not asked to ferry a goat, and also a goat who eats wolves, possibly in addition to the cabbages. This is unusual, as one would expect from Beret Guy's associates. The last panel is a reference to the Trolley Problem , a moral test that asks the participant whether they would passively let people in the way of an uncontrollable trolley die or actively divert the trolley to kill a single person standing on a branch of the tracks. The comic gives a twist here too: according to the title text, the characters must choose between stopping the trolley full of wolves with a cushion of cabbages (in which Black Hat's cabbage moths have laid eggs, which he implicitly argues are morally equivalent to "innocent children") or letting it crash into the river (at which point the wolf who can operate a boat will steal the boat to rescue the wolves from the trolley, which will delay the other characters from crossing the river). The River Crossing puzzle was also mentioned in 1134: Logic Boat and referenced in 589: Designated Drivers . The Trolley Problem was also mentioned in 1455: Trolley Problem and referenced in 1938: Meltdown and Spectre . Unlike typical Logic Boat problems the presence of multiple humans makes finding a solution almost trivial, however trying to determine the solution with the least number of trips could still make the somewhat challenging. Because the set of constraints are both ambiguous and incomplete, it requires the reader to make assumptions that, in turn, will lead to different solutions. The following assumptions can be made based on the setup of the problem or are necessary to avoid an unsolvable puzzle. The trolley problem creates two versions of the puzzle, one where the cabbages are destroyed, the other where they are not and a wolf rescue takes place. The ethical issues associated with the trolley problem are independent from the logic of how to cross the river. With four humans involved, the first trip across can bring an extra human who then can guard the cargo as it is brought across in arbitrary order with care being taken not to have predator and prey alone together at the end. The termites must be last cargo ferried across as they will destroy the boat. The cabbages are destroyed. The second to last trip brings across the last human and the last trip brings across the termites. A pack of wolves is now on the near bank. The last human is brought across in the third to last trip, followed by the last wolf and lastly the termites. No information is provided about whether or not the humans all get along with each other and this is left as a possible exercise for the reader given all of the characters' varying personality traits. However the sailing wolf would likely come in handy if certain humans (ex Black Hat, Beret Guy) cannot be left alone. It is also probable that certain characters might not serve in the capacity as a cargo guard. It is also unclear if humans can leave with their cargo once all the cargo has been brought across. This could complicate matters if a far side "guard" leaves early. [Cueball and Ponytail are standing on the bank of a river. There is a boat in the river. A goat and wolf are also on the riverbank, and Ponytail is holding a cabbage.] Ponytail: I need to cross the river. I have a wolf, a goat, and a cabbage. Cueball: Hmm. [White Hat appears, accompanied by two wolves and pulling a wagon full of cabbages.] Cueball: OK, here's what- White Hat: Hi, I also need to cross. I have two wolves and 100 cabbages. [Black Hat arrives, surrounded by a cloud of flying creatures and carrying a jar of bugs under his arm. Beret Guy follows with another wolf and goat on leashes.] Black Hat: I have 50 cabbage moths and 2,000 boat-destroying termites. Beret Guy: I have a wolf that can operate a boat, and a goat that eats wolves. [The fourth panel is a zoomed-out shot, where everything but the sky appears black.] [A trolley speeds in, leaving a trail of dust in its wake. A person is standing on the front, and many ears are barely visible above the seats.] Cueball: Hang on, I need to make a spreadsheet. Trolley operator: Look out! Trolley operator: My wolf-filled trolley is out of control and can only be stopped by a cushion of cabbages!

Rabbit Introduction

Rabbit Introduction

https://www.xkcd.com/2349

https://www.explainxkcd.com/wiki/index.php/2349:_Rabbit_Introduction

[Cueball is standing in front of a screen and pointing at it with a stick. On the screen is a rabbit shown next to a smartphone, some keys on a key-chain, and two coins. The phone is larger than the rabbit.] Cueball: The US's smallest rabbit species is the pygmy rabbit from the Great Basin area. Cueball: We're seeking a grant to introduce them into the east. [Blondie, White Hat, Megan and Hairy sit behind a long table. Blondie leans both her arms on the table. Hairy has one arm on the table. The other two have their arms down. Cueball replies to Blondie's question from off-panel.] Blondie: Are they native here? Cueball (off-panel): No. Blondie: Will they control some invasive pest? Cueball (off-panel): Dunno! Blondie: Then...Why would you do this? [In a frameless panel Cueball is seen in front of the screen, which is seen from the side. He points to something on the screen with the pointer, while looking over his shoulder.] Cueball: I don't understand. Cueball: Did you see how small they are? Cueball: They're so round! Cueball: Those tiny ears! [Back to the four people behind the desk. Blondie and White Hat are in the same positions but Megan has both her hands up into her hair, and Hairy has one arm on the table, and the other is held up high with a finger pointing up.] Blondie: I see. I'm afraid we'll be denying your grant. White Hat: Hang on. He is right about their ears... Megan: The little feet! Hairy: I vote we fund them!

Cueball is giving a presentation on the pygmy rabbit to a group of panelists, requesting a grant to introduce the species to the eastern United States. The head of the panel, Blondie , asks about typical reasons for introducing a species. If they were native to an area, but had been locally depopulated, re-introduction can help to restore the local ecosystem, but Cueball admits this is not the case. Another reason animal populations may be introduced is to control a local pest. Cueball seems to have no idea what the impact on the local ecosystem would be. In fact, he makes quite clear that his reasoning is simply that the creatures are tiny and cute, and he wants to spread them. He also appears to be entirely perplexed that the panel doesn't feel the same way. Blondie, very reasonably, immediately moves to deny the request. Not only would such a grant expend funds for no legitimate scientific or ecological purpose, but it would risk serious and unstudied impacts on the local ecosystem ( especially considering that this very thing has happened with rabbits before ). However, at this point, the other three panelists - White Hat , Megan and Hairy - have been swayed by Cueball's unconventional argument. All three of them are visibly entranced by the cuteness of the rabbits, and appear willing to fund the request purely based on affection for the animals. This is sort of the opposite of the " charismatic megafauna " method of conservation - charismatic minifauna : the more mini, the more charismatic. The title text mentions the effort to reintroduce the Columbia Basin pygmy rabbit into their native area of the Columbia River drainage basin . It refers to an "Interstate Bun Gap", suggesting a competition between states over which has the most and/or cutest rabbits. That phrase is a reductio ad absurdum of other gaps in capabilities between states and nations, such as the bomber gap and missile gap (widely-publicized shortages - later revealed to be fictional - of the respective nuclear arsenals of the United States compared to the Soviet Union), perhaps similar to the satirical "mine shaft gap" from the 1964 film Dr. Strangelove . This comic continues an xkcd tradition of dealing with the subjective cuteness of rabbits as a scientific discipline ( 1682: Bun ). Randall seems fascinated with the cuteness of lagomorphs, as it is a recurring subject . [Cueball is standing in front of a screen and pointing at it with a stick. On the screen is a rabbit shown next to a smartphone, some keys on a key-chain, and two coins. The phone is larger than the rabbit.] Cueball: The US's smallest rabbit species is the pygmy rabbit from the Great Basin area. Cueball: We're seeking a grant to introduce them into the east. [Blondie, White Hat, Megan and Hairy sit behind a long table. Blondie leans both her arms on the table. Hairy has one arm on the table. The other two have their arms down. Cueball replies to Blondie's question from off-panel.] Blondie: Are they native here? Cueball (off-panel): No. Blondie: Will they control some invasive pest? Cueball (off-panel): Dunno! Blondie: Then...Why would you do this? [In a frameless panel Cueball is seen in front of the screen, which is seen from the side. He points to something on the screen with the pointer, while looking over his shoulder.] Cueball: I don't understand. Cueball: Did you see how small they are? Cueball: They're so round! Cueball: Those tiny ears! [Back to the four people behind the desk. Blondie and White Hat are in the same positions but Megan has both her hands up into her hair, and Hairy has one arm on the table, and the other is held up high with a finger pointing up.] Blondie: I see. I'm afraid we'll be denying your grant. White Hat: Hang on. He is right about their ears... Megan: The little feet! Hairy: I vote we fund them!

Deer Turrets

Deer Turrets

https://www.xkcd.com/2350

https://www.explainxkcd.com/wiki/index.php/2350:_Deer_Turrets

[Black Hat is at a podium, addressing a crowd] Black Hat: Was it a mistake to build turrets that can track nearby wireless devices and fire powerful lasers in their general direction? Black Hat: Sure. I realize that now. [Face-front view of Black Hat] Black Hat: Was it a mistake to mount those turrets on neighborhood deer, release them, then lose interest in the project and move on? Black Hat: Yes. Hindsight is 20/20. [Close-up, Black Hat holds up his index finger] Black Hat: But science is about learning from mistakes Black Hat: And not being afraid to make new ones. [Side view again] Black Hat: Like inviting you here, but not warning you to put your phones in airplane mode. Black Hat: Another mistake. Black Hat: But that's okay. Off-Panel: Gallop gallop Audience member: Is it really?! Black Hat: I think it's fine. Deer: Pew! Pew!

Black Hat has built laser turrets that automatically shoot at nearby wireless devices. This could potentially be useful in a military context, but for reasons unforeseeable , he's gone and strapped them to local deer. Deer are well-defined by their tendency to move around (which Cueball attempted to exploit for ergonomic reasons in 1329: Standing ), typically in areas close to civilization, so attaching wireless-seeking laser robots to them effectively makes them organic killbots. As the last panel reveals, this can be circumvented by disabling wireless access on your devices (airplane mode), though Black Hat doesn't seem particularly concerned with letting people know this, and seems to brush these inventions off as simple mistakes. At least one member of the press isn't convinced, sarcastically asking " is it really ?!" It's not clear if the reporter is asking if it's really "another mistake" (i.e. expressing that this was Black Hat's plan all along), or if it's really "okay", but Black Hat chooses to interpret the question as meaning the latter, and declares that he thinks everything's fine -- after all, he's not the one getting shot by deer-mounted lasers. The title, "Deer Turrets," may be a pun on "deterrents," as laser turrets would certainly deter people with wireless devices from approaching deer. In the second panel Black Hat uses the common idiom "hindsight is 20/20 ". This may be a pun, as "hind" is a term for an adult female (doe) deer - as a counterpoint to the adult male (buck) deer being known as a "stag" - and a "sight" is a visual aligning device , often for weaponry. Whether or not the potential pun has any further caliber to its references, this might be the ultimate aim of this wording. The auto-targeting laser turrets may be a reference to attempts by researchers at the University of Washington to create a laser-based battery charging device [1] . The device in question is mounted on a turret that locates and aims the beam at a photovoltaic cell attached to the battery. The same technology could theoretically be used with a higher-powered laser, but for the application described in the comic, the targeting mechanism would need to be altered to sense any electronic rather than the accompanying photovoltaic cell. In the title text, Black Hat claims that his great grandfather designed the RMS Titanic , the then-largest ocean-liner in the world which sank after striking an iceberg in 1912, and the LZ 129 Hindenburg , the then-largest airship in the world which caught fire and crashed in 1937. He claims that his ancestor did not retire from the design business after the loss of the Titanic , but instead learned from it and made the Hindenburg "iceberg-proof". This is an obvious and humorous lie for several reasons. First, the lead designers of the Olympic -class Titanic and the Hindenburg -class airship were two different people, Lord Pirrie and Dr. Ludwig Dürr respectively, and Black Hat is probably not one of Dürr's great-grandsons (Lord Pirrie had no children). Secondly, while no airship has been recorded to be destroyed by striking an iceberg, it's not because of any "iceberg-proofing" efforts by Black Hat's great-grandfather, or anyone else -- it's just due to the basic fact that airships fly in the air, where there are no icebergs. [ citation needed ] Were an airship to strike an iceberg, it would almost certainly be destroyed; in fact, the even deadlier accident on the airship USS Akron resulted from the airship simply striking the (unfrozen) ocean. The possibility of mounting devices on wild deer was previously referenced in the title text of 1924: Solar Panels . Black Hat has built a similar device to target users of Google Glass in 1251: Anti-Glass . [Black Hat is at a podium, addressing a crowd] Black Hat: Was it a mistake to build turrets that can track nearby wireless devices and fire powerful lasers in their general direction? Black Hat: Sure. I realize that now. [Face-front view of Black Hat] Black Hat: Was it a mistake to mount those turrets on neighborhood deer, release them, then lose interest in the project and move on? Black Hat: Yes. Hindsight is 20/20. [Close-up, Black Hat holds up his index finger] Black Hat: But science is about learning from mistakes Black Hat: And not being afraid to make new ones. [Side view again] Black Hat: Like inviting you here, but not warning you to put your phones in airplane mode. Black Hat: Another mistake. Black Hat: But that's okay. Off-Panel: Gallop gallop Audience member: Is it really?! Black Hat: I think it's fine. Deer: Pew! Pew!

Standard Model Changes

Standard Model Changes

https://www.xkcd.com/2351

https://www.explainxkcd.com/wiki/index.php/2351:_Standard_Model_Changes

[A chart of the Standard Model of particle physics with red marks all over the chart.] Changes I would make to the Standard Model [In reading order:] u up, connected to the down quark below. c charm, connected to the strange quark below, in faded gray with a red l left written over it. Above is a red note with an arrow pointing to the :charm quark. The note reads, Consistent quark names (use "strange" and "charm" for bosons) t top, connected to the bottom quark below. g gluon H Higgs, in faded gray with a red V Vin Diesel writted over it. To the right is a red note with an arrow pointing to the Higgs boson, which reads, With all respect to Peter H, the Higgs boson needs a flashier name d down, connected to the up quark above. s strange, connected to the charm quark above, in faded gray with a red r right written over it. b bottom, connected to the top quark above. γ photon G graviton, in red with a red border. To the right is a red note with an arrow pointing to the graviton, which reads, Let's just include it, it's probably fine e electron, connected to the electron neutrino below. µ muon, connected in faded gray to the muon neutrino below, with red rounded corners cutting it off. τ tau, connected to the tau neutrino below, in faded gray with a red scribble over it. On the tau lepton is a red note which reads, No one needs tau leptons Z Z boson, with the Z symbol and the Z in the name in faded gray. The symbol has a red s written over it and the Z in the name is scribbled out in :red. The word strange is written in red between the symbol and the name. M magic, in red with a red border. To the right is a red note with an arrow pointing to the magic particle, which reads, Decoy particle for people making nonsense claims about "quantum" philosophy stuff v e electron neutrino, with the e as a subscript of the v, connected to the electron above. The v is in faded gray and a red N with a circle around it is written on it. Below is a red note with an arrow pointing to the electron neutrino, which reads, Fix neutrino symbol so I stop mixing up ν and v v μ muon neutrino, with the µ as a subscript of the v, connected to the muon above, in faded gray with a red scribble over it. On the muon neutrino is a red note which reads, Too many neutrinos v τ tau neutrino, with the τ as a subscript of the v, connected to the tau lepton above, in faded gray. Written over it is a D dark matter in red with a red border. Below the tau neutrino is a red note with an arrow pointing to it, which reads, We found it! W W boson, with the W symbol and the W in the name in faded gray. The symbol has a red c written over it and the W in the name is scribbled out in red. The word charm is written in red between the symbol and the name. 🐞 cool bugs, in red with a red border. To the right is a red note with an arrow pointing to cool bugs, which reads, Very small bugs are fundamental particles now

In this comic strip, Randall is proposing some changes to the Standard Model of particle physics. The currently accepted particle table has 17 slots: 12 fermions (first 3 columns of the table - six quarks [top two rows] and six leptons [bottom two rows]) and five bosons (last two columns of the table - four gauge bosons [left hand column] and one scalar boson [right hand column]). This comic consists of a normal version of the particle table to which Randall has made substantial alternations and additions, which are drawn in red over the black and white table. While the Standard Model's predictions are very well supported by experiments, the physics community has identified several flaws in it (e.g. it lacks any particles to convey gravity), and so lots of research is committed to searching for " Physics beyond the Standard Model ". Some of Randall's changes are sort of intended to fill some of those gaps, but for the most part they are nonsensical (although not quite as much as the Turtle Sandwich Standard Model or Fixion ). Randall's proposed changes to the quarks are relatively restrained -- he proposes only that the "strange" and "charm" names should be moved to bosons, while the strange quark should be renamed the "right quark" and the charm quark should be renamed the "left quark", so that all quarks will have "ordinary" directional names. In reality, the original quark model proposed by Murray Gell-Mann included only three quarks, with the "strange" quark so named because the particles that contained them were strangely long-lived relative to their masses. The "charm" quark was so named when it was proposed because it brought a "charming" symmetry to the weak interaction, which we now understand is because it completes the second generation of quarks, along with the strange quark. When a third generation of quarks was proposed, they were called top and bottom by analogy to the up and down quarks (which are so named because of the isospin they carry), though the names 'truth' and 'beauty' were briefly in competition, and colliders working with B quarks are sometimes even now called " Beauty Factories ". Randall likely applied "left" to "strange" and "right" to "charm" simply due to the placement of the particles in the table: In the American English vernacular, the phrase "left and right" is more common than "right and left", in the same way that "top and bottom" is more common than "bottom and top", and "up and down" is more common than "down and up". So he placed "left" above "right" to match the ordering of the other quark generations. While Randall leaves two leptons, the electron and the muon, untouched, he has opted to discard the tau lepton entirely. Each of these three leptons has an associated neutrino; Randall has decided to discard all but the electron neutrino, as he has decided that three are too many neutrino types. He has also replaced the standard symbol for the neutrino, the Greek letter ν (nu), with a capital N, in order to avoid confusion between ν and v, the two letters appearing similar, though this might further be confused with nucleon (particle physicists commonly use N to denote "proton or neutron", and excited states of nucleons are given the symbol N, followed by the mass in parenthesis [1] ) or possibly even with the symbol for Nitrogen (the atomic nucleus with 7 protons and a similar number of neutrons, encountered more in radiology/chemistry as an N, 7 N, 14 N, N + , N 2 and other variations). In place of one of the neutrinos, Randall has introduced a new elementary particle that supposedly explains the existence of dark matter. The nature of dark matter is one of the most famous mysteries in physics: galaxies seem to have much higher gravity than their detectable matter would account for, yet this mysterious form of matter does not seem to interact with other matter in any other detectable way. Neutrinos are known for rarely interacting with other matter, due to their lack of charge, which could justify Randall's decision, but even the little interaction that neutrinos have with the weak force rules them out as candidates for dark matter. Hypothetical sterile neutrinos could be the source of dark matter, and also for the small but nonzero masses of the familiar neutrinos, but no such particles have yet been identified. Together with the arrow, the only one in the comic that points at the particle's box rather than the symbol, the triumphant exclamation "We found it!" probably means that the new "dark matter" entry in the table is the dark matter particle. Randall proposes several new names for existing particles. First, that the W and Z bosons should be renamed to the charm and strange bosons, respectively (taking the names from the quarks), and second, that the Higgs boson should be named the Vin Diesel boson, as he considers Peter Higgs 's name to be too boring to be given to a particle. The Higgs boson is known in the popular press (to the chagrin of many physicists, including Higgs) as " The God Particle ", which is certainly a flashy name, but which itself was changed by the editors of the book of the same name from its authors' originally-intended title: The Goddamn Particle. Randall inserts the graviton, a purely theoretical particle, noting that its inclusion is "probably fine". While the graviton has never been observed, it is occasionally included in diagrams of the standard model to show its hypothetical place, which likely convinced Randall to do the same. Here it is shown below the Higgs boson, implying to be a scalar boson, though it is theoretically a 2nd-order tensor boson (with a spin of 2) and is usually given its own column. Randall also proposes that a false decoy "Magic" particle should be added to the Standard Model, to trip up promoters of quantum mysticism . Presumably, anyone who invokes this particle to support their claims will expose themselves as a fraud, much as cartographers will print trap streets on their maps to catch plagiarism. Finally, Randall adds "Cool bugs" as a fundamental particle, with an explanation of "Very small bugs are fundamental particles now". The title text builds on the "Cool bugs" entry, joking about what spin bugs would have if they were a fundamental particle. The title text references quantum spin number , a property of particles in physics that bears similarities to actual spinning. Although the cool bugs particle is put in the scalar boson group with spin 0, Randall states that it instead has spin 1/2, like a fermion. It is thus not clear whether cool bugs obey the Pauli exclusion principle or not. Unique among elemental particles, cool bugs are affected by wind, which can change their spin. Changes highlighted in red . [A chart of the Standard Model of particle physics with red marks all over the chart.] Changes I would make to the Standard Model [In reading order:] u up, connected to the down quark below. c charm, connected to the strange quark below, in faded gray with a red l left written over it. Above is a red note with an arrow pointing to the :charm quark. The note reads, Consistent quark names (use "strange" and "charm" for bosons) t top, connected to the bottom quark below. g gluon H Higgs, in faded gray with a red V Vin Diesel writted over it. To the right is a red note with an arrow pointing to the Higgs boson, which reads, With all respect to Peter H, the Higgs boson needs a flashier name d down, connected to the up quark above. s strange, connected to the charm quark above, in faded gray with a red r right written over it. b bottom, connected to the top quark above. γ photon G graviton, in red with a red border. To the right is a red note with an arrow pointing to the graviton, which reads, Let's just include it, it's probably fine e electron, connected to the electron neutrino below. µ muon, connected in faded gray to the muon neutrino below, with red rounded corners cutting it off. τ tau, connected to the tau neutrino below, in faded gray with a red scribble over it. On the tau lepton is a red note which reads, No one needs tau leptons Z Z boson, with the Z symbol and the Z in the name in faded gray. The symbol has a red s written over it and the Z in the name is scribbled out in :red. The word strange is written in red between the symbol and the name. M magic, in red with a red border. To the right is a red note with an arrow pointing to the magic particle, which reads, Decoy particle for people making nonsense claims about "quantum" philosophy stuff v e electron neutrino, with the e as a subscript of the v, connected to the electron above. The v is in faded gray and a red N with a circle around it is written on it. Below is a red note with an arrow pointing to the electron neutrino, which reads, Fix neutrino symbol so I stop mixing up ν and v v μ muon neutrino, with the µ as a subscript of the v, connected to the muon above, in faded gray with a red scribble over it. On the muon neutrino is a red note which reads, Too many neutrinos v τ tau neutrino, with the τ as a subscript of the v, connected to the tau lepton above, in faded gray. Written over it is a D dark matter in red with a red border. Below the tau neutrino is a red note with an arrow pointing to it, which reads, We found it! W W boson, with the W symbol and the W in the name in faded gray. The symbol has a red c written over it and the W in the name is scribbled out in red. The word charm is written in red between the symbol and the name. 🐞 cool bugs, in red with a red border. To the right is a red note with an arrow pointing to cool bugs, which reads, Very small bugs are fundamental particles now

Synonym Date

Synonym Date

https://www.xkcd.com/2352

https://www.explainxkcd.com/wiki/index.php/2352:_Synonym_Date

[Ponytail and Hairy talking.] Ponytail: So, how is she? Hairy: Well...she's a talented writer. Seems very cool. Ponytail: ...but? Hairy: She's really into...synonyms. Ponytail: I don't understand. Hairy: Her hobby is finding the most unsettling possible words for any sentence. Ponytail: Word games? That doesn't sound too bad. Hairy: Well... [Caption above reads "Earlier..."] [Megan is wearing a dress and talking to Hairy, who is dripping wet.] Megan: Ugh, it's so watery out. Megan: You must be clammy! Want to guzzle some tea? [Hairy is now less wet and holding a cup of warm tea.] Megan: Let me slough off this dress, Megan: and slither into something more comfortable.

Ponytail asks Hairy about Megan , his date. Hairy mentions that she's a talented writer and seems cool, but when prompted by Ponytail, says Megan is into synonyms. Megan apparently enjoys unsettling Hairy with words. Ponytail thinks word games aren't too bad, and she would be right if it weren't for Megan's unsettling use of them. In the next panel (labeled "Earlier..."), it's raining (or humid), and Hairy comes back in. Megan comments, "Ugh, it's so watery out. You must be clammy! Want to guzzle some tea?" replacing wet (or humid ), cold (or sweaty ), and drink with more suggestive, possibly-repulsive-sounding words. "Clammy" does technically refer to having damp skin, but it is usually used in the context of nervousness or illness, and "guzzle" suggests very rapid consumption, which is not a safe way of drinking hot tea, and is also considered rude when enjoying a meal with others, especially romantic interests. Continuing, she says, "Let me slough off this dress, and slither into something more comfortable," replacing take (or remove , or disrobe ) and slip . This last sentence of course strongly suggests snakes shedding their skin. Serpentine movements are sometimes regarded as alluring and attractive , but people usually don't favorably compare their clothing to snakes' skin care. [ citation needed ] She further elaborates on this in the title text, saying "We need some grub to munch -- I'll go slouch over to the kitchen." By using the word "grub," she presumably means the slang term for basic food like the type served in pubs (which is often greasy fast-food, served in a dirty -- one might even say grubby -- environment), though it may also invoke the image of white insect larvae, like pale lumps of flesh squirming in a dark hole, while "slouching" has connotations of laziness or suspicious activity, rather than romance. Excessive use of uncommon words is a common trope in fiction, and also seen in real life. Usually, the speaker is trying to demonstrate their superior intelligence or knowledge. Megan, on the other hand, seeks to use a similar tactic to make listeners uncomfortable. The words she's using aren't especially complex or uncommon, and they're technically correct, but they've been selected to evoke disgust in the listener. Strange synonyms were also the focus in 1322: Winter , and a similar concept was the joke in 919: Tween Bromance (although in that strip, Cueball was making Megan uncomfortable). Megan has previously shown off her love of uncomfortable puns ("Vore of the Roses") in 2245: Edible Arrangements . Randall has written many comic strips before about his (comical, fictional) hobbies , but this is the first time he's written about someone else's hobby. [Ponytail and Hairy talking.] Ponytail: So, how is she? Hairy: Well...she's a talented writer. Seems very cool. Ponytail: ...but? Hairy: She's really into...synonyms. Ponytail: I don't understand. Hairy: Her hobby is finding the most unsettling possible words for any sentence. Ponytail: Word games? That doesn't sound too bad. Hairy: Well... [Caption above reads "Earlier..."] [Megan is wearing a dress and talking to Hairy, who is dripping wet.] Megan: Ugh, it's so watery out. Megan: You must be clammy! Want to guzzle some tea? [Hairy is now less wet and holding a cup of warm tea.] Megan: Let me slough off this dress, Megan: and slither into something more comfortable.

Hurricane Hunters

Hurricane Hunters

https://www.xkcd.com/2353

https://www.explainxkcd.com/wiki/index.php/2353:_Hurricane_Hunters

[Black hat facing left] Black Hat: Yes, flying into the eye of a hurricane is dangerous. [Cueball on left at a desk being addressed by Black Hat on the right] Black Hat: But it provides us with crucial data that helps us understand and predict these storms. [Same as previous cell, with Black Hat raising his hand] Cueball: But your passengers had bought tickets to St. Louis. Black Hat: They should be proud of our contributions to meteorology! Everything on Cueball's desk has gone missing in panel 3.

The comic strip opens with Black Hat explaining to Cueball (who is presumed to be some government official) that flying into hurricanes, while risky, provides valuable scientific data. Although the eye itself is relatively calm, it is surrounded by the eyewall , a region of extremely intense thunderstorms. Thus, the danger of flying through such storms must be carefully weighed against the scientific knowledge being gained. In the real world, such missions are conducted by highly-trained pilots with specialized aircraft, such as the NOAA Hurricane Hunters and the US Air Force's 53rd Weather Reconnaissance Squadron (also nicknamed "Hurricane Hunters"). However, Cueball's comment in the third panel shows that Black Hat is not discussing the activity of hurricane hunting in general, but rather is attempting to justify his decision to fly a passenger jet through the eye of a hurricane. Passenger airliners are not meant to fly into hurricanes, [ citation needed ] and can easily crash there. It's not clear if Black Hat is (somehow) a jet pilot himself, has come into ownership of an airline and was merely directing a flight, or, probably most likely , simply hijacked the flight he happened to be on, but the commercial jet passengers were not expecting to "participate" in a hurricane hunting mission. Black Hat replies that, instead of being upset, the passengers should be proud of their contributions to meteorology, but their contribution is probably negligible, as they were not actively collecting useful scientific data. This comic is likely referencing both Hurricane Laura , which was active during the week prior to this comic strip's publication, and Microsoft Flight Simulator 2020 , which players have been utilising the software's ability to simulate real-time weather to fly into and explore the (virtual) aforementioned hurricane. The simulator currently only has passenger aircraft available to pilot, echoing Black Hat's flying of a commercial jet into a hurricane. A similar situation where historical/well-documented experimental techniques are used in inappropriate situations occurs in 1594: Human Subjects , albeit by test subjects rather than “researchers”, if Black Hat can be called that. In the title text, Black Hat says that their flight gathered data on the possibility of making loops in the eye of the hurricane by passenger airliners, but if it had actually done a loop, he probably would have said so. The Boeing 707 was made to successfully execute a barrel roll and fly inverted during a 1955 test flight . If no flight envelope protections are active, barrel rolls are possible with any aircraft and any helicopter, because the aircraft and its fuel systems only experience mild and positive g loads, never negative ones. Likewise, the air flow stays the same as in level flight. Problematic is ending the barrel roll, as there is a possibility of exceeding the safe speed limits. Another passenger jet that was barrel-rolled is the Concorde . Pilots Brian Walpole and Jean Franchi did on a test flight - not once, but several times. Loops are a lot more problematic because of the speeds reached when ending the maneuver, and the speed needed to begin it. But like the barrel roll, a loop can be flown while only experiencing mild and positive g loads. In fact, Harold E. Thompson flew several loopings in a Sikorsky S-52 , a helicopter first flown in 1947. Prolonged inverted flights, though, cause negative g forces, an altered air flow, and cause havoc with the fuel systems, parts of which are gravity-driven. Aircraft that can fly inverted for longer than a few seconds are specifically designed, for example aerobatic aircraft and fighter jets. It is possible that this is his justification of why the flight contributed to meteorology. However, passenger airliners' abilities to do loops has nothing to do with that field of science. Moreover, the same data could be gathered by flying the same airliner without passengers, or with willing ones. [Black hat facing left] Black Hat: Yes, flying into the eye of a hurricane is dangerous. [Cueball on left at a desk being addressed by Black Hat on the right] Black Hat: But it provides us with crucial data that helps us understand and predict these storms. [Same as previous cell, with Black Hat raising his hand] Cueball: But your passengers had bought tickets to St. Louis. Black Hat: They should be proud of our contributions to meteorology! Everything on Cueball's desk has gone missing in panel 3.

Stellar Evolution

Stellar Evolution

https://www.xkcd.com/2354

https://www.explainxkcd.com/wiki/index.php/2354:_Stellar_Evolution

[Miss Lenhart stands in front of a chalkboard. On the board are squiggly lines of text and a series of growing circles] Miss Lenhart: After a star begins fusing hydrogen, it may reach a stable equilibrium in which it separates from Massachusetts and develops a thriving lobster industry. Miss Lenhart: This is known as the Maine Sequence.

This is a pun on the main sequence , the continuous and distinctive band of stars that appear on Hertzsprung–Russell diagrams . Stars on this band are known as main-sequence stars. These are the most numerous stars in the universe, and include the Earth's Sun. The main sequence forms a major part of a star's life cycle, with smaller stars spending more time on it, where they transform hydrogen to helium via nuclear fusion to generate energy and sustain themselves. Miss Lenhart starts off apparently describing the main sequence. However, she veers off into the history of Maine , the most northeastern of the 48 contiguous US states. She mentions the separation of Maine from Massachusetts and its lobster fishing industry, similar to how, soon after the beginning of their lifespans, stars evolve from early stages (like T-Tauri stars) and go onto the main sequence, where they become stable and stay for a long time. She makes a play between "main" and the U.S. state of " Maine ", which are homophones . The allusion to stars might also be a reference to the representation of individual states as stars on the canton of the US flag. The title text puns on either the state or the star slowly growing for a long time, before suddenly becoming "redder". In the case of the state, the population of Maine has been slowly but steadily growing over the last century, increasing from about 700,000 in 1900 to about 1,350,000 in 2020. [1] Similarly, stars with a mass of 0.6–10 M☉ slowly grow while they are on the main sequence, then increase in size and leave the main sequence in the subgiant phase, before suddenly becoming red giants. In American politics, "red" most recently refers to the Republican party (NBC showed Republicans in blue and Democrats in red until 1996, and CNN until 1992). While in the past Maine has frequently voted for Democratic party candidates, Republican party candidates have increasingly won more campaigns or lose campaigns with larger minorities of the vote. For instance, Maine, which has used a district-based voting system, voted in its entirety for the Democratic party presidential candidates in the 1992, 1996, 2000, 2004, 2008, and 2012 presidential elections, but one of its districts voted for Republican candidate Donald Trump in 2016 and 2020. Meanwhile, a main sequence star transitions eventually into a red giant , also becoming "redder". Alternatively, the color change could refer to lobsters; when one is cooked, it turns from a bluish-green to a bright red-orange. "Red" is unfortunately also used in the derogatory terms "rednecks" for rural lower income folks (Maine is a predominantly rural, lower income state), and "redskins" for indigenous Native Americans (discussion of indigenous empowerment has been rising in Maine). [Miss Lenhart stands in front of a chalkboard. On the board are squiggly lines of text and a series of growing circles] Miss Lenhart: After a star begins fusing hydrogen, it may reach a stable equilibrium in which it separates from Massachusetts and develops a thriving lobster industry. Miss Lenhart: This is known as the Maine Sequence.

University COVID Model

University COVID Model

https://www.xkcd.com/2355

https://www.explainxkcd.com/wiki/index.php/2355:_University_COVID_Model

[Cueball and Megan are talking to each other.] Cueball: Apparently some university reopened based on a COVID model developed by two physicists. Megan: Uh oh. [Cueball raises an arm slightly.] Cueball: But even their worst-case model underestimated the number of student parties and they had to shut down. [Cueball holds up a finger.] Megan: Can't understand why someone with a physics degree would be bad at judging how often college students get invited to parties. Cueball: Excuse me, I was invited to multiple parties. Cueball: And attended both of them!

This comic is another in a series of comics related to the COVID-19 pandemic . Cueball begins telling Megan an anecdote about how a college decided to reopen "based on a COVID model developed by two physicists." (The incident in question is likely a reference to this article and tweet about the University of Illinois, that went viral with similar wording the day before the comic was published). Presumably, the model predicted that the university could allow students to return to campus while still keeping cases of COVID-19 under control, perhaps using some combination of reduced classroom and residence hall density, and by implementing policies against large social gatherings. Before he can get further, Megan interrupts him with "Uh oh," perhaps worried that an epidemiological model created by people who aren't epidemiologists could be ineffective. Alternately, she may be expressing concern specifically about physicists' epidemiological modelling. Cueball then confirms her fears by saying that the model underestimated how many parties the students would hold, and so the actual number of cases on campus has turned out to be greater than even their worst-case prediction. Megan facetiously wonders how a physicist could have failed to know how much college kids party, implying that physicists do not attend many parties. Cueball, representing Randall , a physics major, then retorts that he "was invited to multiple parties! And attended both of them!" implying first that he was invited to many parties over an undefined period of time at college, but then admitting it was only two. In the title text, Randall, no longer in-character, admits to attending at least a third party, and possibly a few more that have been forgotten, and confirms this was over the entire course of his degree studies, likely 4-8 years or more. This demonstrates, as an introverted physics major who struggles with social interactions , he (and by implied extension most Physics majors) has little interest in attending parties. As many other people go to college for the parties rather than the education [ citation needed ] , we can only imagine how severely his campus epidemiology model would underestimate the number of opportunities for the coronavirus to spread. A nontrivial number of colleges followed this trajectory in 2020, such as the aforementioned University of Illinois at Urbana-Champaign . A different comic with physicists modeling another field is 793: Physicists . [Cueball and Megan are talking to each other.] Cueball: Apparently some university reopened based on a COVID model developed by two physicists. Megan: Uh oh. [Cueball raises an arm slightly.] Cueball: But even their worst-case model underestimated the number of student parties and they had to shut down. [Cueball holds up a finger.] Megan: Can't understand why someone with a physics degree would be bad at judging how often college students get invited to parties. Cueball: Excuse me, I was invited to multiple parties. Cueball: And attended both of them!

Constellation Monstrosity

Constellation Monstrosity

https://www.xkcd.com/2356

https://www.explainxkcd.com/wiki/index.php/2356:_Constellation_Monstrosity

[Within a frame, a long title is written in a short arc above the drawn elements] Virgibrascorpleo [Upon a background of astrological imagery merged in accord, basic point-and-line astronomical/astrological representations of Scorpio, Libra, Virgo and Leo are illustrated.] [(Scorpio may be slightly rotated/translated for aesthetic reasons.)] [Red lines have been added to link stars in adjacent constellations.] [ Beta Scorpii may be connected to Sigma Librae (once known as Gamma Scorpii)] [ ...also Pi Scorpii may be connected to Tau Librae ] [ Beta Librae may be connected to Mu Virginis ] [ Nu Virginis may be connected to Beta Leonis (better known as Denebola )] [Caption below the frame] I got kicked out of the International Astronomical Union for adding extra lines between the constellations to create a monstrosity.

Constellations in the night sky are formed by pattern-forming various asterisms and other stellar relationships in the night sky. Being rather subjective, different cultures have inculcated differences in their interpretations, some subtle and others less so, for the exact same objective views of the night sky. Even where the same groupings are recognised, different cultures can 'see' different forms behind that group of stars. However, observers in the southern hemisphere will see entirely new constellations not visible to those in the northern one, and vice-versa, whilst observing those patterns fully visible to both (on the ecliptic ) as inverted and therefore may inspire vastly different conceptualised images or even connectivities. The International Astronomical Union has demarcated the sky into 88 constellations , mostly those known to ancient Greece (catalogued by Ptolemy) plus southern constellations designated by astronomers during the European Renaissance. Randall has taken one particular zodiac (or at least part of the hellenic one, closely tied to western astrology and still inspiring astronomical naming) and imagined further lines connecting stars to link up four separate constellations, to create a portmanteau constellation with a portmanteau name. As a matter of fact, this connection is half true, since Libra used to be the two claws of a much larger Scorpio, the larger constellation having been split in two when the twelve zodiac signs were set as they are now. The four constellations used here are Scorpio (the scorpion), Libra (the scales), Virgo (the virgin/maiden) and Leo (the lion), sequentially spread across the sky in positions relating to a span of astrological dates running 'backwards' from late November through to late July. The name Randall gave this meta-constellation, however, uses a different order to combine as "Virg(o, l)ibra(, )scorp(io & )leo". Possibly "Scorlibirgoleo", or a similar mash-up with the same source order, did not roll together nicely enough for his liking. In reality, any apparent proximity of stars on the celestial sphere does not guarantee an actual proximity in the depths of space, either within or between constellations. Knock-on effects from this renaming would not change actual scientific understanding, but it could have a knock-on effect upon star catalogues and databases if this object regrouping forces so many incidental name changes to the current referencing system, which is why the astronomers are upset (as indicated in the title text). Similarly, astrology's conceit based upon four separate 'characters' and life-paths, arising from birth-signs and planetary transits across four distinct areas of the sky, would lose 'precision' if forced to accept a single symbolic area in their stead. Astrologers would be very upset because their work (interpreted charitably) is related to understanding the influences of the stars on life on Earth; they might be concerned that " crossing the stars " could lead to " disaster ". It's not clear how Randall hoped to alter the practices of either group with his changes, but he was banned from the IAU for his efforts ( not the first time this has happened ). Randall previously mentioned being banned from the IAU in 541: TED Talk , but the reason stated in that comic was "redefinition of the 'planet' to include the IAU presidents' mom", so presumably he was reinstated and then banned again. This monstrosity is reminiscent of the infamous 2009 Dutch horror film known as The Human Centipede , in which three humans are bound together such that their digestive systems are connected in sequence. In this image, the head of Virgo appears to be connected to the hindquarters of Leo, and likewise the mouthparts of Scorpio are fixed to the bottom of the "stand" of Libra. Libra's stand appears to go under Virgo's dress; to form a complete "celestial centipede", it should attach to Virgo's hindquarters, but judging by the connection between stars, it probably (mercifully) connects to her foot. [Within a frame, a long title is written in a short arc above the drawn elements] Virgibrascorpleo [Upon a background of astrological imagery merged in accord, basic point-and-line astronomical/astrological representations of Scorpio, Libra, Virgo and Leo are illustrated.] [(Scorpio may be slightly rotated/translated for aesthetic reasons.)] [Red lines have been added to link stars in adjacent constellations.] [ Beta Scorpii may be connected to Sigma Librae (once known as Gamma Scorpii)] [ ...also Pi Scorpii may be connected to Tau Librae ] [ Beta Librae may be connected to Mu Virginis ] [ Nu Virginis may be connected to Beta Leonis (better known as Denebola )] [Caption below the frame] I got kicked out of the International Astronomical Union for adding extra lines between the constellations to create a monstrosity.

Polls vs the Street

Polls vs the Street

https://www.xkcd.com/2357

https://www.explainxkcd.com/wiki/index.php/2357:_Polls_vs_the_Street

White Hat: Polls are just numbers. White Hat: You have to talk to people on the street . White Hat: Polls say most people support <Candidate X>. White Hat: But the people I talk to on the street support <Candidate Y>. White Hat: Polls claim most people don't live in my town and have never been here. White Hat: But the people I meet on the street tell a very different story. White Hat: According to polls , most people don't like playing in traffic. White Hat: So why do I never seem to meet these people on the street ?

This comic discusses getting data or opinions through a study (polls) or by getting them anecdotally (on the street). The phrase "voice on the street" is commonly used by news reporters who get opinions on issues by literally asking people walking by what they think, and has been previously mentioned (and derided) in 756: Public Opinion . Many news organizations, and other data-driven institutions, conduct or commission polls to assess the opinions of the general public. These polls generally rely on asking a randomly selected and anonymous set of people a set of consistent, prepared and deliberately crafted questions about their opinions, experiences, and intents. The results of these polls are traditionally held to reflect the views of the public as a whole, within certain margins for error. Many news shows also conduct "man-on-the-street" interviews (more formally known as vox populi , "voice of the people"), to provide a human face of "the public" and engage viewers more. Many pollsters, pundits, and politicians worry that polling data may not accurately reflect the true trends in public opinion, as in the infamous " Dewey Defeats Truman " newspaper headline, and so White Hat is here extolling the virtues of interviewing "real people" to get at that ground truth. White Hat suggests that, while polls suggest "candidate X" is more favored, the people on the street that White Hat interviews are more supportive of "candidate Y". He implies that his experiences reflect reality better than the polls. There are a number of reasons why polls may not be entirely representative. The sampling method might not be genuinely random, some groups might be less likely than others to respond to a poll, and it's argued that some people express views that they consider to be more socially acceptable, even in anonymous polls, but vote differently in actual elections (examples include the " Bradley effect " and the " shy Tory factor "). Despite these concerns, there is little evidence that individual conversations do a better job at determining public opinion than polling. However, attempting to get a person from off the street to report for a news anchor instead would obviously exacerbate all of these problems immensely, rather than fixing anything. This comic is very likely a reference to the 2020 United States presidential election , which occurred on November 3, 2020 (about 2 months from the time of the comic's publication), which Democrat Joe Biden won. Most polls showed Biden polling ahead of incumbent Donald Trump, but Trump and his supporters frequently argued that the polls are inaccurate, often arguing that they personally knew or talked to many Trump supporters, and few Biden supporters. At the same time, the fact that Trump won the 2016 election astonished many (including Randall) who had seldom met Trump supporters in their own lives and within their own social circles. This kind of anecdotal evidence is generally a poor basis for gauging public support, for multiple reasons. Politics in the US are frequently regional, so sampling in a single area is unlikely to be representative of the whole country, or even a whole state. It's not uncommon for gathering places (both physical and virtual) to attract people from one political group more than another, producing a skewed sample. If someone uses their own perception, rather than rigorous analysis, confirmation bias is likely to have a major impact (a person might pay more attention to supporters of their preferred candidate, and ignore political opponents). This strip lampoons such thinking, as it quickly becomes clear that White Hat's methodology is heavily driven by selection bias. He's apparently talking only to the residents of his town, and extrapolating those results to the whole country. By that logic, he would conclude that everyone has visited his town, and most people live there. It is true that he's getting "ground truth", but it's also true that he's only sampling a very small (and highly idiosyncratic) part of the whole population. The punchline in the final panel is a joke about the phrase "on the street". Usually this phrase means "anywhere out in public where the interviewer can openly approach people" (often a sidewalk near the studio), but White Hat is presumably taking the phrase literally and interviewing people he meets on the roadway. In the US, roads are generally reserved for vehicles (cars, trucks, motorcycles and in most areas bicycles), and walking or standing in the roadway for long periods is dangerous and usually illegal. White Hat's sample population thus consists only of the people who can be found on the roadway outside of designated pedestrian zones, who are generally from the small fraction of the population who have no qualms about the risks of being struck by moving vehicles or causing accidents when drivers swerve to avoid them. The title text is a joke about selection bias and tautology . People who don't feel like taking surveys wouldn't get as far as answering a survey question about survey questions. However, it does touch on an issue raised by FiveThirtyEight after the election: that polls only measure people who are interested in answering polls, and that population may not be politically representative of the entire country . White Hat: Polls are just numbers. White Hat: You have to talk to people on the street . White Hat: Polls say most people support <Candidate X>. White Hat: But the people I talk to on the street support <Candidate Y>. White Hat: Polls claim most people don't live in my town and have never been here. White Hat: But the people I meet on the street tell a very different story. White Hat: According to polls , most people don't like playing in traffic. White Hat: So why do I never seem to meet these people on the street ?

Gravitational Wave Pulsars

Gravitational Wave Pulsars

https://www.xkcd.com/2358

https://www.explainxkcd.com/wiki/index.php/2358:_Gravitational_Wave_Pulsars

[Single panel with Ponytail and Cueball standing facing each other] Ponytail: Ask me what the secret to detecting gravitational waves using pulsars is. Cueball: What's the secret to detecting grav— Ponytail: Timing!

Pulsars are rotating neutron stars, which have a very precise period of rotation. Pulsars are highly magnetized, causing a them to emit a beam of electromagnetic radiation that rotates across their sky. Radio astronomers can detect these beams if and when they point towards Earth, where they appear as pulses of radiation with highly stable periods. They use the pulsars' periodic beams to try to detect gravitational waves by tracking the rotation period of an ensemble of pulsars extremely precisely over long periods of time. Disturbances in the pulsars' rotation period will be measurable at Earth. A disturbance from a passing gravitational wave will have a particular signature across the ensemble of pulsars, and will be thus detected. The process is called "pulsar timing" , or just "timing" for short. Ponytail presents this to Cueball as a joke - specifically, a joke about comedy. One of the most important aspects of comedy is revealing the punchline with correct timing. Ponytail sets Cueball up for a joke like, "Ask me what the secret of comedy is." / "What's the secret of--" / "Timing!" In this format, the punchline ("Timing!") deliberately comes too soon, which makes it funny because the timing is bad. Ponytail also replaces the secret to comedy with the secret to detecting gravitational waves with pulsars, to set up the joke about the word "timing". The title text is a play on a well-known real estate saying that the three most important parts of a real estate deal are "location, location, location." In 3D Euclidean space , the three Cartesian coordinates {X, Y, Z} all refer to locations along the three axes. [Single panel with Ponytail and Cueball standing facing each other] Ponytail: Ask me what the secret to detecting gravitational waves using pulsars is. Cueball: What's the secret to detecting grav— Ponytail: Timing!

Evidence of Alien Life

Evidence of Alien Life

https://www.xkcd.com/2359

https://www.explainxkcd.com/wiki/index.php/2359:_Evidence_of_Alien_Life

[The comic is laid out like a 3 by 3 grid, with the amount of evidence down the left-hand side (Weak Evidence of Alien Life/Promising Evidence/Definite Evidence) and the type of reaction across the top (Not Cautious Enough/Appropriately Cautious/Too Cautious). Each box is a combination of the row label and column label.] [Row 1: Weak Evidence of Alien Life] [Column 1: Not Cautious Enough] [Cueball is looking through a telescope. There is a long, thin asteroid seen through the telescope, shown on the upper-left hand corner in the panel.] Cueball: This asteroid is probably an alien probe! [Column 2: Appropriately Cautious] [Same scene as before, except the asteroid is omitted.] Cueball: This asteroid is weird and we should take a closer look. Cueball: It's not aliens. [Column 3: Too Cautious] Cueball: This asteroid appears to be far away, but it could also be nearby and just very small. [Row 2: Promising Evidence] [Column 1: Not Cautious Enough] [Ponytail runs excitedly to Cueball. She carries a notepad with a V on it.] Ponytail: They found life on Venus! [Column 2: Appropriately Cautious] [Same scene, except Ponytail is simply looking at her notepad.] Ponytail: These molecules might be produced by life, or by weird high-heat chemistry. [Column 3: Too Cautious] [Same scene, except Ponytail's arm is slack by her side.] Ponytail: There is growing evidence that the atmosphere on Venus contains molecules. [Row 3: Definite Evidence] [Column 1: Not Cautious Enough] [There is a UFO with two aliens coming out of it. Cueball excitedly runs to the aliens, while Megan waits. There are three UFOs flying in the background.] Cueball: I'm going to go give those aliens a hug! [Column 2: Appropriately Cautious] [Two aliens are on the ground, and the foreground UFO is no longer in the frame. Cueball is talking to Megan. There are three UFOs in the background.] Cueball: Oh wow, aliens! Cueball: Should we try to communicate? [Column 3: Too Cautious] [Three UFOs are shooting beams into the United Nations building, vaporizing it. Cueball and Megan are watching.] Megan: The energy beams vaporizing the United Nations could be a possible biosignature.

This comic depicts a table of possible responses to new information on the possibility of alien life. It is presented in table form, with the columns representing three categories of reaction to new evidence, and the rows representing the strength of new evidence, increasing down the table. Each intersection then shows a small scenario of what the response would be. The left and right-hand column scenarios are hyperbolic in either their acceptance or denial. The center column represents a reasonable course of action. This comic was a reaction to the discovery of phosphine gas on Venus , which is where Ponytail's "V" figure in the second row comes from (a representation of the phosphine absorption feature). Phosphine is a molecule whose presence in the Venusian atmosphere came as a surprise. Light breaks phosphine down, meaning something must be producing it. However, there is no known abiotic mechanism on Venus that would produce the gas in the quantities observed. The phosphine could therefore be a sign of life on Venus, but more evidence is needed. Venus was also an unexpected place to find a possible sign of life — although it was a common pulp fiction setting in the early 20th-century , the arrival of the space probe era dashed hopes that the hidden surface might be, say, an exotic jungle (one of the more common pulp-fiction concepts). More recent efforts at finding life in the Solar System have mostly focused on Mars and various ice moons with suspected subsurface oceans , but life more-or-less as we know it could exist within the upper atmosphere of Venus, which has more Earth-like conditions than the surface. However, while the discovery of phosphine is interesting, it is not nearly enough evidence to claim that "life has been found" on Venus, and likewise, it is comically understated to refer to the paper as "evidence of molecules" in Venus's atmosphere. The title text refers to an action which is simultaneously too cautious and not cautious enough: the speaker is skeptical that aliens exist, which is usually an appropriate belief, except that presumably Megan and Cueball are in the situation presented in the bottom row, where aliens have landed right in front of them. Rather than modifying his belief (presumably it's Cueball, who was the one to approach the aliens in the other panels), he expresses an intention to approach the alleged aliens and attempt to remove their masks. He believes that he will expose a human wearing a costume, perpetrating a "Scooby-Doo"-style hoax , but no matter what the outcome is, he's acting rashly. If the beings before him are aliens, he will be initiating a very aggressive first contact and will likely receive a violent response, and even if the alien is not violent, Cueball might end up removing an environmental apparatus that is protecting it from Earth's environment (or vice versa). On the other hand, even if the "aliens" really are fakes, Cueball might end up injuring someone who is just playing a harmless joke (and who'd want to keep some kind of mask on to reduce the spread of COVID-19 ). In the first row, an asteroid looks like an "alien probe". The "least cautious" response immediately jumps to the conclusion that the asteroid is an alien probe. The "too cautious" response simply ignores the asteroid, while the "appropriately cautious" response seeks to discover more information about the asteroid. The "alien probe" asteroid refers to 'Oumuamua , which passed through the Solar System in 2017. 'Oumuamua's hyperbolic trajectory indicated interstellar origin. Because of the unusual elongated shape suggested by its albedo (the object was never visualized as more than a point source of light) and indications of a slight non-gravity related acceleration, there were many wild speculations about 'Oumuamua's origin, including it being an alien probe similar to the one presented in the science fiction classic Rendezvous with Rama . The image of an astronomer looking through a telescope and being alarmed by seeing "something huge" which is actually very small and very close is an old comic gag , but the difference in parallax would immediately distinguish a close asteroid from a far one. The second row refers to the discovery of phosphine gas on Venus, with the "least cautious" response to simply conclude that there is life on Venus. The "appropriately cautious" and "too cautious" responses provide more general conclusions about "molecules" on Venus. In the final row, aliens have arrived on Earth. The insufficiently cautious approach is to immediately hug them. Cueball might make a new friend, but he might also be mistaken as an attacker, or perhaps the aliens are intending to make a meal of whoever approaches them. The more responsible approach is to (consider attempting to) communicate at a distance. In the final panel, the United Nations building is being vaporized by energy beams. This is technically "just" a "possible biosignature", as there are abiotic stellar events that produce energetic beams (although those are usually the size of planets or stars rather than buildings) and the beams could also be of human origin , but debating such semantics in the face of such destructive power seems excessively pedantic. For that matter, even though that panel is presented as "too cautious", it's only "too cautious" in the sense of "discussing the possibility of alien life"; Megan and Cueball are showing extreme lack of caution by remaining in the vicinity of an alien attack. The destruction of human governmental buildings is a common trope in science fiction films, as a way of aliens removing the ability of humanity to co-ordinate a response to an attack. The United Nations building is allegedly the co-ordination centre for a worldwide response to an extraterrestrial incursion. However, since popular culture in the USA currently doesn't pay much attention to the United Nations, in American movies it is more commonly the White House or larger cities like New York or Los Angeles that get blown up by aliens. [The comic is laid out like a 3 by 3 grid, with the amount of evidence down the left-hand side (Weak Evidence of Alien Life/Promising Evidence/Definite Evidence) and the type of reaction across the top (Not Cautious Enough/Appropriately Cautious/Too Cautious). Each box is a combination of the row label and column label.] [Row 1: Weak Evidence of Alien Life] [Column 1: Not Cautious Enough] [Cueball is looking through a telescope. There is a long, thin asteroid seen through the telescope, shown on the upper-left hand corner in the panel.] Cueball: This asteroid is probably an alien probe! [Column 2: Appropriately Cautious] [Same scene as before, except the asteroid is omitted.] Cueball: This asteroid is weird and we should take a closer look. Cueball: It's not aliens. [Column 3: Too Cautious] Cueball: This asteroid appears to be far away, but it could also be nearby and just very small. [Row 2: Promising Evidence] [Column 1: Not Cautious Enough] [Ponytail runs excitedly to Cueball. She carries a notepad with a V on it.] Ponytail: They found life on Venus! [Column 2: Appropriately Cautious] [Same scene, except Ponytail is simply looking at her notepad.] Ponytail: These molecules might be produced by life, or by weird high-heat chemistry. [Column 3: Too Cautious] [Same scene, except Ponytail's arm is slack by her side.] Ponytail: There is growing evidence that the atmosphere on Venus contains molecules. [Row 3: Definite Evidence] [Column 1: Not Cautious Enough] [There is a UFO with two aliens coming out of it. Cueball excitedly runs to the aliens, while Megan waits. There are three UFOs flying in the background.] Cueball: I'm going to go give those aliens a hug! [Column 2: Appropriately Cautious] [Two aliens are on the ground, and the foreground UFO is no longer in the frame. Cueball is talking to Megan. There are three UFOs in the background.] Cueball: Oh wow, aliens! Cueball: Should we try to communicate? [Column 3: Too Cautious] [Three UFOs are shooting beams into the United Nations building, vaporizing it. Cueball and Megan are watching.] Megan: The energy beams vaporizing the United Nations could be a possible biosignature.

Common Star Types

Common Star Types

https://www.xkcd.com/2360

https://www.explainxkcd.com/wiki/index.php/2360:_Common_Star_Types

[A chart, with ten colored circles representing stars of different colors and sizes. Each circle has a label, with a line going from the label to the circle. Below each label is a small description in smaller font. The text is listed from the top left. Above all the circles is the following heading:] Common star types [A small yellow star.] Yellow dwarf Warm, stable, slowly-growing [An even smaller white star.] White dwarf Small, hot, dim [A very large red-orange star squishing the previous two stars into the corners of the chart.] Red giant Huge, cool, luminous [A small red star.] Red dwarf Small, cool, ancient, dim [An olive green, medium-sized star.] Green elf Old, diminishes into the west [A fairly large pale blue star.] Blue giant Large, hot, short-lived [A blue-green, medium-sized star.] Teal sphynx Cryptic, eternal [A small silver-colored star.] Gray wizard Wise, powerful, mercurial [A tiny blue star.] Indigo banshee Bright, portentous, extremely loud [A beige, medium-sized star.] Beige gorgon Dangerous to observe at optical wavelengths.

This 'infographic' chart purports to be a comparative guide to various star types, often described by a basic color, which is something that even naked-eye astronomy has determined, and may be qualified as 'dwarf' or 'giant' to describe relative sizes. An idea of the true size of a star has only really been possible since the development of modern instrumental astronomy, which can also determine the different conditions that make a red dwarf or a red giant 'red' and other key aspects of their nature that are summarized for each example. See table below . In true xkcd tradition, this is taken beyond reality. The pantheon of stars illustrated extend the use of 'dwarf' and 'giant' as if describing mythical or fictional beings, drawing upon others from the fantasy ilk with hues and shades that may not be typically described, or even encountered, by astronomers. The aspect information provided for these 'star' types is based upon the respective mythologies. The title text is in the style of a Wikipedia page's hatnote / reference note. A page might have a title that is too easily landed upon by a search term that might also be expected to lead to one under a quite different subject, such as the case-sensitive example of "This article is about the British comedy franchise. For the type of star, see Red dwarf ." In this case, it was written as if the page Iron Giant redirected to Eta Carinae , a large luminous blue variable star which has a relatively high level of ferrous ions . Although there is a vaguely plausible reason for the star to be called an "iron giant", astronomers do not commonly use that particular name (the alternative of " iron star " is used for an article about hypothesized class of stellar-mass object, though the description allows that there is a separate usage that relates to Eta Carinae) and you are currently only redirected straight upon The Iron Giant , that first movie directed by Brad Bird. This note was added to Wikipedia, but quickly removed. [A chart, with ten colored circles representing stars of different colors and sizes. Each circle has a label, with a line going from the label to the circle. Below each label is a small description in smaller font. The text is listed from the top left. Above all the circles is the following heading:] Common star types [A small yellow star.] Yellow dwarf Warm, stable, slowly-growing [An even smaller white star.] White dwarf Small, hot, dim [A very large red-orange star squishing the previous two stars into the corners of the chart.] Red giant Huge, cool, luminous [A small red star.] Red dwarf Small, cool, ancient, dim [An olive green, medium-sized star.] Green elf Old, diminishes into the west [A fairly large pale blue star.] Blue giant Large, hot, short-lived [A blue-green, medium-sized star.] Teal sphynx Cryptic, eternal [A small silver-colored star.] Gray wizard Wise, powerful, mercurial [A tiny blue star.] Indigo banshee Bright, portentous, extremely loud [A beige, medium-sized star.] Beige gorgon Dangerous to observe at optical wavelengths.

Voting

Voting

https://www.xkcd.com/2361

https://www.explainxkcd.com/wiki/index.php/2361:_Voting

[Cueball walks in from right, staring at his phone and talking to Megan.] Cueball: I will crawl across broken glass to vote this year if I have to. Megan: ...Why would there be broken glass? Megan: There aren't even any big windows at our polling place. [Cueball raising a finger triumphantly.] Cueball: I will wait in line till the sun burns out. Megan: Ok, some places have lines, which is awful, but it's usually pretty quick here? Megan: Definitely not 5 billion years. [Cueball raising a fist.] Cueball: I will walk barefoot across hot coals to cast my ballot! Megan: Where would you even find coals? Megan: You can wear shoes to vote. This scenario makes no sense. [Cueball raising a finger, and walking back off-panel to the left] Cueball: I will swim across a shark-filled channel! Megan: That'll take you way outside our precinct. Cueball: Then I'll swim back! Megan: Can you do all this stuff after voting?

The run-up to the 2020 United States elections , occurring on November 3, 2020 (less than 2 months from the time of the comic's publication), has been fraught with various overlapping worries about the legitimacy of the forthcoming result. The COVID-19 pandemic has created a new interest in voting by mail , at a historically large scale. See Postal voting in the United States for more detail. Cueball, however, is in a very patriotic mood and makes a series of hyperbolic statements to Megan about the trials he would be willing to endure in order to vote in the upcoming elections, none of which would (hopefully), in reality, apply to his or anyone else's circumstance. Crawling across broken glass might have actually been necessary at some polling sites of the 2001 New York City mayoral election primary, which had begun on September 11, 2001, and would have continued had it not been postponed two weeks due to the terrorist attacks of that day. However, as Megan states, their polling sites, unlike those of the 2001 election, don't even feature any especially large windows or other such structures from which broken glass could be derived. The idea of being so intent on doing something (in this case, voting) that a person claims to be willing to crawl across broken glass to do so is a common expression. The Sun, currently a yellow dwarf star on the main sequence, will eventually expand into a red giant, then collapse down to a white dwarf when its fuel is exhausted; this will not happen for billions of years, as Megan points out. Because of this, waiting until the sun burns out would result in Cueball's vote not being counted at all, both because it would be after the official deadline for ballots to be cast and because there would no longer be anyone alive on Earth. As Megan observes, hot coals would most likely not even be present at their polling stations, and although some states have been accused of trying to make voting inconvenient or unsafe, this comic has not yet led any states to prohibit wearing shoes at polling places. According to Megan, her and Cueball's municipality does not even include a single shark-infested body of water that Cueball would be able to swim through in order to cast his vote. Cueball's solution to this problem is to simply swim back to their location after swimming in his shark-filled channel. Megan tries in vain to convince Cueball that his proposed actions are unnecessary or even impossible in their area, but, unable to bring him back to reality, she closes the final panel by asking if he'd be willing to put off all of this dangerous stuff until after voting, perhaps so that he will be alive long enough to vote in the first place. Broken glass, the extinction of humanity, hot coals, and sharks aside, though, Cueball faces the risk of contracting COVID-19 from being in such close proximity to so many other voters, as he seems to plan on voting in person (his words show his desire for activities only possible by way of physical action; in the title text, he also ignores Megan when she says that mail-in voting is available). In the title text, Megan tells Cueball that he does not need to go to such lengths to vote, as their state has mail-in voting and already sent forms either to cast a ballot or to apply for mail-in ballots. Cueball ignores her and continues looking online for shark-filled channels to swim through. In doing so, he completely negates his professed desire to vote, as he is ignoring the easy path and going after paths that would end up making it impossible to cast his vote. Alternatively, he may just be caught in the normal rabbit hole of doing Internet research, where you start researching one thing (voting locations) and end up reading about another (locations of shark-infested channels). Randall is making the point that, despite apparent obstruction tactics and threats and attempts to de-legitimize the process, voting is very important (Cueball is using hyperbole to illustrate the importance), and relatively easy (as Megan keeps reminding him). He is also expressing an opinion that the increased danger of system compromise harming the legitimacy of the voting process due to massive mail-in voting is less worrisome than the corona-virus pandemic keeping people from voting at all, if in-person voting were the only viable option. Randall lives in Massachusetts, a state with majority Democrat media, voters, and government. Sharks are sighted off Cape Cod on occasion, so if he really wanted to, he could swim with them, but unless he lives on Cape Cod itself, it would take him very far outside his voting district. [Cueball walks in from right, staring at his phone and talking to Megan.] Cueball: I will crawl across broken glass to vote this year if I have to. Megan: ...Why would there be broken glass? Megan: There aren't even any big windows at our polling place. [Cueball raising a finger triumphantly.] Cueball: I will wait in line till the sun burns out. Megan: Ok, some places have lines, which is awful, but it's usually pretty quick here? Megan: Definitely not 5 billion years. [Cueball raising a fist.] Cueball: I will walk barefoot across hot coals to cast my ballot! Megan: Where would you even find coals? Megan: You can wear shoes to vote. This scenario makes no sense. [Cueball raising a finger, and walking back off-panel to the left] Cueball: I will swim across a shark-filled channel! Megan: That'll take you way outside our precinct. Cueball: Then I'll swim back! Megan: Can you do all this stuff after voting?

Volcano Dinosaur

Volcano Dinosaur

https://www.xkcd.com/2362

https://www.explainxkcd.com/wiki/index.php/2362:_Volcano_Dinosaur

[Megan is standing facing right, talking to Cueball who is sitting at a computer desk and also facing right, looking at a computer screen.] Cueball: Oh cool, they just found a dinosaur that was buried by a volcanic eruption 125 million years ago. Megan: Wow. [Pause. Megan is still facing right. Panel closes in on Megan and Cueball is not shown. This panel has no dialogue.] [Megan has stepped closer to Cueball, who leans in and is still looking at the screen.] Megan: Was it okay? Cueball: Hmm, it doesn't say.

This comic is a reference to this discovery of fossils of dinosaurs that were buried and killed by a volcanic eruption . Megan asks if the dinosaur was okay. As living things typically don't survive being fossilized in volcano debris [ citation needed ] , the answer to the question would obviously be "no", but Cueball replies that he is unsure. Even if the dinosaur somehow survived the initial burial, it would be very difficult for it to survive being buried for 125 million years. 2020 probably wouldn't be the best year to dig it up and potentially let it free. It is not an uncommon shortcut to refer to finds of relatively intact fossilized pieces of an animal using wording that sounds like they found an entire animal intact, as in the headline "New dinosaur discovered" rather than a wordier but more accurate "the fossil of a new dinosaur" or "the fossilized bones of a new dinosaur". Most parts of an animal dead for millions of years don't survive that length of time, and those that do are usually transformed into something else, such as bones becoming fossilized into rock and minerals. Megan's response is natural and expected in many situations when hearing of a person or creature experiencing misfortune. The humour here comes from the inaptness of asking the question millions of years after the event. Rather than responding to the ridiculousness of Megan's question, Cueball takes it seriously, and deadpans that he can't tell. The title text suggests contacting its " next of kin ", which usually means a nearest living relative, e.g. a brother or a sister. The process of identifying and contacting next of kin is a standard step performed by authorities in the event of a death being discovered. The reason for this step is to allow the next of kin to exercise their rights to the property of the deceased under inheritance law. In this case, non-avian dinosaurs are extinct [ citation needed ] , so it is the job of phylogeneticists (those who study evolutionary relationships) to determine which living animal (presumably a bird of some kind) is the "nearest relative" to the deceased dinosaurs. However, even if the correct species could be identified, the specific animal would be all but impossible to find. Statistically speaking, that dinosaur is almost certainly either a direct ancestor of all living birds , or else an ancestor of no living birds. [Megan is standing facing right, talking to Cueball who is sitting at a computer desk and also facing right, looking at a computer screen.] Cueball: Oh cool, they just found a dinosaur that was buried by a volcanic eruption 125 million years ago. Megan: Wow. [Pause. Megan is still facing right. Panel closes in on Megan and Cueball is not shown. This panel has no dialogue.] [Megan has stepped closer to Cueball, who leans in and is still looking at the screen.] Megan: Was it okay? Cueball: Hmm, it doesn't say.

Message Boards

Message Boards

https://www.xkcd.com/2363

https://www.explainxkcd.com/wiki/index.php/2363:_Message_Boards

[Single panel showing a view of the "MopedPro" forum on a message board, with a caption below the panel.] Forum Tab: MopedPro Forum (Top Left) | (4 tabs with illegible writing on them. None of them appear to be selected) (Top Right) NIN85 (posted December 5, 2000 - 13:01): So mad that my mom won't let me get a Vespa. I'm old enough for a moped license and they're really not that dangerous. JULZ [new user] (posted September 23, 2020 - 17:05): At least she's not stopping you from getting an electric scooter you don't even need a license for NIN85 (posted September 23, 2020 - 18:36): Okay, Julian, (a) you know we talked about this, and (b) how the heck did you find this thread [Caption below the comic]: I love that message boards are now old enough for this to happen.

The joke of this comic lies in the dates of the forum posts and the (presumed) relation between the posters. The initial post was made in 2000 by NIN85 who was, at the time, a teenaged girl (likely 14 or 15 years old given that her username ends in "85," implying she was born in 1985), complaining that her mother did not allow her to get a Vespa . Vespa is a brand of scooters and mopeds produced by the Italian manufacturer Piaggio. Most U.S. states require motorcycle licenses for any vehicle with an engine size over 50 cubic centimeters. Most Vespas are larger than this, although 49 CC models (classified as mopeds) do exist. Depending on the state, the minimum age to get a moped in the United States is 14, 15, or 16. The reply was written in 2020 (twenty years later) by JULZ (or Julian), the presumed son of the now-adult NIN85, likely in his teenage years. The "Z" may refer to "Generation Z", paralleling the "85." "JULZ" complains about his mother refusing to allow him to get an electric scooter, which doesn't require a license. He is implicitly pointing out the hypocrisy of his mother, as a fifteen-year-old, thinking that teenagers with scooters are perfectly reasonable, while as a thirtyfive-year-old, being against the idea. The primary source of humor in this strip (made explicit in the caption) derives from the fact that the Internet has been in common use for so long that teenagers can now look up old posts that their parents made when they, themselves, were teenagers. The late 1990s to early 2000s was right around the time the average person would be expected to have access to the internet and use it regularly, which means that, as of 2020, that's been the case for around one human generation. This can be jarring for people who are still used to thinking of the Internet as a new technology. Noting how much time has passed since events that feel recent is a recurring theme in xkcd. Of course, the basic premise of this exchange is nothing new. Teenagers have encountered (and been surprised by) the notion that their parents were once young for as long as there have been people. In the past, it's happened through finding old photographs, old videos, old diaries, or simply by hearing stories from their family and old friends. Young people are often shocked by what they learn, and accuse their parents of hypocrisy when they punish behavior that they once engaged in. Of course, this isn't true hypocrisy: we expect teenagers to grow and evolve, and develop mature, adult viewpoints. Parents naturally have both more understanding of dangers and lower tolerance for risk when dealing with their children. This strip points out that the internet has now existed for long enough (and preserves archives for long enough) that it's now become a potential medium for this whole dynamic. Part of the humor results from the unexpected situation that the child went to the trouble of tracking down his mother's old forum post, and that his mother is still active in the same niche forum 20 years later (as evidenced by her rapid response). In the title text, the parent is apparently a moderator on that board now, or at least can quickly twist the ear of an actual mod. She has the thread locked (preventing further replies) and threatens banning the kid if he does not learn to post new threads, instead of dredging up dead threads from two decades ago. The act of reviving long-dead threads is often called "thread necromancy" or "necroing," and many forums (and users) frown upon it. It is seen as similar to bringing up a conversation from ages ago in real life. It often adds nothing new, and the original participants in the discussion may no longer be active or no longer interested in the topic. Some forums may actually encourage tagging onto existing but idle discussions (to add new or updated information) rather than repeatedly creating new threads, but that does not seem to be the case here. Invoking the power of moderation could suggest that, in typical parental fashion, she's using her greater influence and social position to end the discussion, making clear that she's the one in charge. "You'll be banned from this forum thread" could be seen as the Internet version of "as long as you live under my roof, you'll live by my rules". [Single panel showing a view of the "MopedPro" forum on a message board, with a caption below the panel.] Forum Tab: MopedPro Forum (Top Left) | (4 tabs with illegible writing on them. None of them appear to be selected) (Top Right) NIN85 (posted December 5, 2000 - 13:01): So mad that my mom won't let me get a Vespa. I'm old enough for a moped license and they're really not that dangerous. JULZ [new user] (posted September 23, 2020 - 17:05): At least she's not stopping you from getting an electric scooter you don't even need a license for NIN85 (posted September 23, 2020 - 18:36): Okay, Julian, (a) you know we talked about this, and (b) how the heck did you find this thread [Caption below the comic]: I love that message boards are now old enough for this to happen.

Parity Conservation

Parity Conservation

https://www.xkcd.com/2364

https://www.explainxkcd.com/wiki/index.php/2364:_Parity_Conservation

[Cueball is standing in front of an oval wall mirror hanging over a small table. He's holding a tube connected to an electronic device. A face is dimly reflected in the mirror.] Cueball: Listen, I know I said your name three times. Cueball: But before you come out of the mirror and murder me, can you hold this cobalt-60 and take some measurements? Cueball: See, I'm researching parity conservation... [Caption below the comic]: It took some negotiating, but I've finally become the first person to coauthor a paper with Bloody Mary.

Bloody Mary is a legend of a ghost, phantom, or spirit conjured to reveal the future. She is said to appear in a mirror when her name is chanted repeatedly. This is why Cueball says he said her name three times. This is her second apperance in xkcd, the first being 555: Two Mirrors . The remark on parity conservation and cobalt-60 is likely a reference to the Wu experiment . In 1956, physicist Chien-Shiung Wu and her team at the National Bureau of Standards used cobalt-60 to show that the weak interaction breaks parity: beta particles leave the decaying nucleus in the direction opposite to nuclear spin. One of the results of this is that it becomes possible to differentiate between the concepts of left and right on a purely technical level, even if the person (or distant alien) you're talking to can't see you. When we say that "parity is not conserved," we mean that the concepts of left and right are not purely symmetrical across all areas of physics. As Richard Feynman put it, this means that "nature's laws are different for the right hand and the left hand, that there's a way to define the right hand by physical phenomena." It seems as if Cueball is trying to "hand" Bloody Mary his experimental apparatus either physically (as he is asking her to take the cobalt-60 "before [she] come[s] out of the mirror"), or perhaps by reflecting it onto her side. Because Bloody Mary exists in mirrors, her world is implicitly a mirror of ours. This would allow her to conduct mirror physics experiments, such as whether or not the beta particles leave the cobalt-60 in the same direction as they do in our universe. The title text references antimatter . In physics, antimatter is like a mirrored version of matter — mirrored in charge, parity, and time — composed of antiparticles rather than particles. Antimatter and matter spontaneously annihilate each other when they meet, releasing extremely high-energy radiation. Therefore, Bloody Mary being made of antimatter explains why she kills people when she comes out of the mirror. (Bloody Mary would also be annihilated in such an interaction, so the fact that she keeps coming back may be attributable to her being a ghost.) There have been a lot of science fiction-y stories featuring antimatter people; often, these are duplicates of "regular"-matter people. The stories often show unrealistic ideas of what would happen if matter and antimatter versions of people met. Sometimes, the duplicates simply disappear; sometimes, if the plot requires it only one may disappear. Or sometimes the entire universe is destroyed. In reality, what would happen is that the matter and antimatter would mutually annihilate, as pairs of subatomic particles, creating enormous radiation and heat. It's likely that only a small fraction of the matter and antimatter would actually come into contact, rather than being propelled apart by the explosion. Indeed, if the duplicates are in their versions of air, the air and anti-air particles would interact first! Even in interstellar space, an antimatter alien would give off significant radiation from collisions with matter particles. In these stories, it's often presumed that the corresponding duplicates of people can annihilate only each other, but can safely touch anything else. In reality, the matching is at the subatomic level: any proton with any antiproton, any electron with any antielectron (or "positron"), etc. [Cueball is standing in front of an oval wall mirror hanging over a small table. He's holding a tube connected to an electronic device. A face is dimly reflected in the mirror.] Cueball: Listen, I know I said your name three times. Cueball: But before you come out of the mirror and murder me, can you hold this cobalt-60 and take some measurements? Cueball: See, I'm researching parity conservation... [Caption below the comic]: It took some negotiating, but I've finally become the first person to coauthor a paper with Bloody Mary.

Messaging Systems

Messaging Systems

https://www.xkcd.com/2365

https://www.explainxkcd.com/wiki/index.php/2365:_Messaging_Systems

A Venn Diagram is shown, framed in a box. It has three components: Vaguely Modern, E2E Encrypted, Supported By Everyone Items Solely in the Vaguely Modern category are: Facebook Messenger, Hangouts, Discord, Various DMs Items In both 'Vaguely Modern' and 'E2E Encrypted' categories are: Signal, iMessage, Whatsapp Items Solely in the E2E Encrypted category are: PGP Email, Various Obscure Projects, Skype I think, XMPP and XMPP + XEP-0384: OMEMO Items Solely in the 'Supported By Everyone' category is: SMS All other categories are empty. [Caption below the comic]: Why SMS refuses to die

Messaging systems suffer from the network effect , as in order to communicate, both parties need to be using the same system. Though relatively ancient by modern standards, SMS is supported by almost every mobile device (unless you're using a kosher phone or still on a DynaTAC ) that has a phone number attached, which means if you want to send a message to someone, but aren't sure if you have a messaging protocol in common, you can be sure at least they have SMS. The comic mentions many other communication systems, which offer various advantages in either security ( end to end encryption ) and or a bunch of general improvements filed under the label "vaguely modern", such as longer character limits and the ability to share media such as images in-service. The messaging systems are shown in a Venn Diagram , with the categories corresponding to these three advantages. The intersections between the categories are very minimal: there are a few systems that have both E2E encryption and are modern, but no intersections with "supported by everyone", and SMS is the only system in that category. So when choosing a method of communication, you're usually faced with a compromise. The title text proposes an alternative, absurd mingling of technologies in the vein of 1636: XKCD Stack . IRC is Internet Relay Chat, a similarly antiquated messaging service that may also never die, as suggested in 1782: Team Chat . Transport Layer Security (TLS) is a layer of networking software that provides encrypted communication. DOSBox is an emulator that recreates the operating environment of MS-DOS ; part of the absurdity is that DOSBox is intended almost solely for video games. Additionally, this hodgepodge of technologies is running in a mobile browser, instead of a dedicated server or machine. Various other comics have referenced the issue of chat services, including 1810: Chat Systems , 1254: Preferred Chat System , and 1782: Team Chat . Slack Facebook Messenger Hangouts Discord Various DMs End-to-end encryption refers to messaging systems where only the communicating users can read the messages posted. In principle, it prevents potential eavesdroppers – including telecom providers , internet providers , and even the provider of the communication service – from being able to access the cryptographic keys needed to decrypt the conversation. PGP Email Various Obscure Projects Skype I Think XMPP ( Jabber + TLS ) Signal iMessage WhatsApp SMS RCS (Rich Communication Services) is a more modern protocol, aimed at replacing SMS and MMS protocols. RCS support has been slow to rollout among cellular carriers, due to their preference for proprietary implementations and monetizable usage tracking and/or gatekeeping. Like SMS and MMS, RCS is a federated network, wherein failure of one provider's systems is unlikely to result in a total system outage. The single-provider messaging networks of other widely used systems (such as those mentioned on this page) can experience system-wide outages that prevent all users from communicating via them at all; this has happened multiple times for both Signal and Discord, among others. For this reason, single-provider networks are intrinsically more prone to total system outages than federated networks. The long-standing interoperability of SMS+MMS networks is difficult (if not impossible) to match in terms of communicating with a maximum number of people, and maintaining functionality for other users when one provider experiences an outage. A Venn Diagram is shown, framed in a box. It has three components: Vaguely Modern, E2E Encrypted, Supported By Everyone Items Solely in the Vaguely Modern category are: Facebook Messenger, Hangouts, Discord, Various DMs Items In both 'Vaguely Modern' and 'E2E Encrypted' categories are: Signal, iMessage, Whatsapp Items Solely in the E2E Encrypted category are: PGP Email, Various Obscure Projects, Skype I think, XMPP and XMPP + XEP-0384: OMEMO Items Solely in the 'Supported By Everyone' category is: SMS All other categories are empty. [Caption below the comic]: Why SMS refuses to die

Amelia's Farm Fresh Cookies

Amelia's Farm Fresh Cookies

https://www.xkcd.com/2366

https://www.explainxkcd.com/wiki/index.php/2366:_Amelia%27s_Farm_Fresh_Cookies

[What looks like the back of a package of cookies is shown.] [Top left: Product logo.] Amelia's Farm-Fresh Cookies [Parts of an oval surround the logo] [Middle left: What appears to be a standard Nutrition Facts panel, though the details are illegible squiggles] [Bottom left: What appears to be an ingredients list, though the details are illegible squiggles, and a few other squiggles] [Right side:] Our Story Growing up on my grandma's farm, I spent so many cozy mornings in the kitchen, watching her take trays of fresh-baked cookies from the oven. Her cookies were just awful . She used the finest ingredients. Eggs straight from the coop, stone-ground flour, hand-churned butter. But she squandered them. It's so sad. She told me I was too picky, but I know what cookies are supposed to taste like. When I started a bakery, I vowed not to repeat her mistakes. These cookies won't fall apart in your hands. They have gooey centers, and slightly crisp exteriors, not the other way around, Grandma . There's no mysterious gritty texture. Why would there be? If you enjoy these cookies, please write to my grandma to let her know. Thanks! Amelia [A partially legible squiggled address appears at the bottom left of the Our Story part of the box. The bracketed dashes represent portions that are illegible.] Ms W[——] M[——] 1[—] A[——] Ln O[——], FL 328[–]1

The comic portrays the back side of a box of cookies (evidenced by the nutrition facts -style table on the left side). Many brands have a romanticized origin story on their packaging explaining the name or how they have a secret ingredient. Instead, this brand's origin story is a tale of petty one-upmanship as the brand's founder sets out to prove that her cookies are better than her grandmother's. Grandma's cookies were apparently very fragile and crumbly. They also had "gooey exteriors and slightly crisp interiors." Normally items bake from the exterior in, so how the interior had gotten crisp and the exterior hadn't is not explained (maybe Grandma "bakes" them in a microwave oven ?). Grandma's cookies also had a "mysterious gritty texture", perhaps from sand getting into the flour from the stone grinders, that was unpleasant to Amelia. To complete her revenge, the "story" contains the grandmother's address. Creating false addresses for their mascots is often used as a publicity stunt for children to write testimonials to the brand's PR or marketing department. However, here it appears to be Amelia's actual Grandma's actual address, the goal being for her to receive thousands of letters on a regular basis about how her granddaughter's cookies are so great, while jabbing "unlike yours!" In retaliation, Amelia's grandmother has started submitting (presumably bogus) food safety complaints about Amelia's bakery to the health department in a ploy to overburden the bakery with unnecessarily frequent inspections. At one point Amelia eventually decided to offer a truce, which her grandmother emphatically rejected, underscoring it by sending Amelia an extra-large batch of the cookies she knows Amelia hates. While the name of the city past the first letter and at least one of the zip code digits is too illegible to read, by process of elimination it is plausible that the city is Orlando and the zip code is 32891 (or less likely, 32861). No other location in Florida consists of one word starting with O and a zip code legibly close to the one in the comic. [What looks like the back of a package of cookies is shown.] [Top left: Product logo.] Amelia's Farm-Fresh Cookies [Parts of an oval surround the logo] [Middle left: What appears to be a standard Nutrition Facts panel, though the details are illegible squiggles] [Bottom left: What appears to be an ingredients list, though the details are illegible squiggles, and a few other squiggles] [Right side:] Our Story Growing up on my grandma's farm, I spent so many cozy mornings in the kitchen, watching her take trays of fresh-baked cookies from the oven. Her cookies were just awful . She used the finest ingredients. Eggs straight from the coop, stone-ground flour, hand-churned butter. But she squandered them. It's so sad. She told me I was too picky, but I know what cookies are supposed to taste like. When I started a bakery, I vowed not to repeat her mistakes. These cookies won't fall apart in your hands. They have gooey centers, and slightly crisp exteriors, not the other way around, Grandma . There's no mysterious gritty texture. Why would there be? If you enjoy these cookies, please write to my grandma to let her know. Thanks! Amelia [A partially legible squiggled address appears at the bottom left of the Our Story part of the box. The bracketed dashes represent portions that are illegible.] Ms W[——] M[——] 1[—] A[——] Ln O[——], FL 328[–]1

Masks

Masks

https://www.xkcd.com/2367

https://www.explainxkcd.com/wiki/index.php/2367:_Masks

[A chart is shown with a title and explanation at the top:] Masks By effectiveness at preventing respiratory virus transmission [The chart consist of a vertical line going top to bottom with arrows at both ends. There are labels at the top, aorund the middle and at the bottom:] Not effective. Effective Extremely Effective [Along the line there are 12 bullets. From each bullet there goes a line (often with one or two turns) to a depiction of a type of mask. Each mask type is labeled. The first six masks are all close to the top, the last only halfway down to the middle of the line. The next two are right around the middle, then two are halfway towards the bottom from there and the final two are close to the bottom, with the last very close to the botom. From top to bottom:] Zorro/Lone Ranger Batman Theater Skincare Scarecrow Guy Fawkes Cloth SpiderMan N95 Scuba Vader Mysterio

This comic is another in a series of comics related to the COVID-19 pandemic . This comic is a line from top to bottom explaining how good different types of masks are at preventing respiratory virus transmission. As with many comics in 2020, it is a reference to the 2020 pandemic of the coronavirus SARS-CoV-2, which causes COVID-19, a virus that primarily transmits through air droplets expelled from the human nose and mouth. This comic may have been inspired from a Polygon article published on May 15th . [02%] Zorro/Lone Ranger [03%] Batman [07%] Theater [10%] Skincare [15%] Scarecrow [18%] Guy Fawkes [48%] Cloth [52%] Spider-Man [68%] N95 [71%] Scuba [80%] Vader [90%] Mysterio [A chart is shown with a title and explanation at the top:] Masks By effectiveness at preventing respiratory virus transmission [The chart consist of a vertical line going top to bottom with arrows at both ends. There are labels at the top, aorund the middle and at the bottom:] Not effective. Effective Extremely Effective [Along the line there are 12 bullets. From each bullet there goes a line (often with one or two turns) to a depiction of a type of mask. Each mask type is labeled. The first six masks are all close to the top, the last only halfway down to the middle of the line. The next two are right around the middle, then two are halfway towards the bottom from there and the final two are close to the bottom, with the last very close to the botom. From top to bottom:] Zorro/Lone Ranger Batman Theater Skincare Scarecrow Guy Fawkes Cloth SpiderMan N95 Scuba Vader Mysterio

Bigger Problem

Bigger Problem

https://www.xkcd.com/2368

https://www.explainxkcd.com/wiki/index.php/2368:_Bigger_Problem

[Cueball, holding a clipboard next to his body in his left hand, holds his right hand palm up towards White Hat.] Cueball: I'm trying to fix <problem with the world>. Can you help? [Cueball stands with both arms down while white Hat lift one hand up toward Cueball.] White Hat: It's obvious you don't actually care. If you did, you'd be trying to fix <bigger problem> instead. [Same setting as the first picture, wit Cueball's hand a bit further out towards White Hat.] Cueball: Okay, want to help fix <bigger problem>? White Hat: No, for another reason I'll think of later.

Cueball is asking White Hat to help fix an unspecified problem with the world. Presumably, he is working for some form of charity and perhaps asking for donations or signatures. White Hat responds by saying that Cueball doesn't care (about, presumably, the world) and that he would be working to fix an unspecified larger issue if he really cared. Cueball then asks if White Hat would rather be working to solve that problem. However, White Hat says that he doesn't want to, but that he also hasn't come up with an excuse not to yet. White Hat seems as if he couldn't be bothered, and wants to go on with his life. The claim that someone is not working towards an important issue, while not always completely invalid , is commonly used as a cheap tactic to ignore a solution to a problem, even when the person using it does want to help out with either cause and is also a logical fallacy known as the " Not as bad as " fallacy, Fallacy of Relative Privation , or Appeal to Worse Problems . In the last panel of this comic, White Hat reveals that he isn't sufficiently devoted to either cause to act on them, so that his bringing up the larger issue appears less like interest in the larger issue than an excuse to not support Cueball's cause. The title text furthers this point. While the argument used by White Hat is supposed to imply that the person giving the argument cares about an issue that matters more (to the exclusion of the other issue), it's often used, as seen in this comic, as an excuse to not work to fix any problem, making it "a real slam-dunk argument against fixing any of them." Both causes in the comic are referred to ambiguously and surrounded with angle brackets to imply that they can be filled it with any two problems, as the comic is supposed to depict a common situation that happens during discussions of many different causes. This comic is quite similar to 871: Charity because both have a character that responds to people trying to help "by figuring out a reason that they're not really as good as they seem". Additionally, it seems to relate to 1447: Meta-Analysis on being very meta. 1232: Realistic Criteria has an extremely similar conversation between Cueball and White Hat. People sometimes use similar fallacious reasoning against themselves, thinking that they shouldn't tackle "simple" "unimportant" problems when there are "important" problems outstanding, even if the former are within their ability to handle but the latter aren't. This can be a form of self-sabotaging behavior. In essence, this may be an example of the principle "The perfect is the enemy of the good." That is, it is better to make a small advance which does some good. If you insist on doing nothing until you cure everything to perfection, nothing will be done. [Cueball, holding a clipboard next to his body in his left hand, holds his right hand palm up towards White Hat.] Cueball: I'm trying to fix <problem with the world>. Can you help? [Cueball stands with both arms down while white Hat lift one hand up toward Cueball.] White Hat: It's obvious you don't actually care. If you did, you'd be trying to fix <bigger problem> instead. [Same setting as the first picture, wit Cueball's hand a bit further out towards White Hat.] Cueball: Okay, want to help fix <bigger problem>? White Hat: No, for another reason I'll think of later.

All-in-One

All-in-One

https://www.xkcd.com/2369

https://www.explainxkcd.com/wiki/index.php/2369:_All-in-One

[A large printer-like machine, with the label All-in-One Paper Processor on the top left of it. There are three columns of functions, with a few of them having a green light. At the top of the machine is a "paper feed" tray. At the bottom of the machine, is a large hole, for outputting the paper.] Column 1 Print (lit green) Copy Fax (lit green) Shred Scan Translate Summarize Plagiarize Collate (lit green) Column 2 Staple (lit green) Remove staples Add those perforated edge strips that are so fun to tear Roll Burn Eat Column 3 Fold airplane Origami flower Corrugate Paper-mâché Découpage Notarize (lit green) Biodegrade Crumple and throw at trash like a basketball (lit green)

This is an xkcd-style parody of an all-in-one printer , a printer which typically can perform several functions, usually printing, scanning, copying, and faxing. This machine starts off with fairly standard printer functions but quickly becomes absurd. The machine is accordingly oversized, making room for all the status indicators and (presumably) the extra internal parts required to accomplish the uncommon functions. The title text says that if both the "scan" and "shred" options are selected, it now scans documents before trying to destroy them. Previously the machine destroyed documents and then scanned the pieces and tried to reconstruct them, identifying the original location of each shredded piece on the original sheet(s) of paper, which takes a large amount of processing power. Certain functions are lit green, indicating they are in use. To show which ones are in use, they are highlighted green (selected) . [A large printer-like machine, with the label All-in-One Paper Processor on the top left of it. There are three columns of functions, with a few of them having a green light. At the top of the machine is a "paper feed" tray. At the bottom of the machine, is a large hole, for outputting the paper.] Column 1 Print (lit green) Copy Fax (lit green) Shred Scan Translate Summarize Plagiarize Collate (lit green) Column 2 Staple (lit green) Remove staples Add those perforated edge strips that are so fun to tear Roll Burn Eat Column 3 Fold airplane Origami flower Corrugate Paper-mâché Découpage Notarize (lit green) Biodegrade Crumple and throw at trash like a basketball (lit green)

Prediction

Prediction

https://www.xkcd.com/2370

https://www.explainxkcd.com/wiki/index.php/2370:_Prediction

[White Hat and Cueball standing next to each other. Cueball has his palm out.] Cueball: Event A is more likely than Event B. [White Hat touches chin thoughtfully] White Hat: So you're saying that Event A will happen. Cueball: No, Event B could also happen. [A frameless panel] White Hat: So you're saying it's 50/50. Cueball: No, it's definitely not 50/50. [Cueball produces a phone] White Hat: Sounds like you have no idea what will happen. Cueball: And yet I knew exactly how this conversation would go. Here, listen: [Cueball clicks a button on his phone] *Click* Phone: Then you'll say, "So it's 50/50"

This comic is about misunderstanding probability . Sometimes people will incorrectly assume that if two events are possible, and one of them is more likely than the other to occur, then the first event WILL occur; or, that if one names two or more outcomes they are equally likely to occur when in fact they might have different probabilities. Saying that one event is more likely to happen than another is not the same as saying that the first event is definitely going to happen. A statement like "event A has a 70% probability of happening" often misleads people into believing that event A is inevitable, while in fact 3 times out of 10 event B will happen instead of A. Some don't like probability statements because they are not definite and therefore cannot be proven wrong. For example, if a probability statement says "event A has a 1% probability of happening" and event A actually happens, that does not prove the statement wrong, because the statement admits of the possibility of event A happening. For example, FiveThirtyEight famously gave Trump a higher odds, 28.6% of winning the 2016 U.S. presidential election than most other models did just before the election, but still not more likely than his opponent. However, many readers at the time interpreted that as "Trump is definitely going to lose", and after he won that election, blasted FiveThirtyEight for getting its prediction "wrong". However, that interpretation is mistaken. 28.6% means Trump had a real chance at winning: if you could put election results in a hat and draw them at random, he would win two out of every seven tries. For another example, in tabletop gaming terms, Trump's likelihood of winning was slightly lower than that of passing a flat check with a DC of 15 (6/20 or 30%). The correct interpretation of a probability statement like "event A has a 70% probability to happen" is that in the long run, about 70% of events with this probability end up happening. If, for example, 99% of those events ended up happening, the 70% probabilities you gave those events may likely be wrong (you should've given probabilities closer to 99%), even though you "called" almost all events correctly (in the sense that 70% means the events are more likely to happen than not to happen, and almost all of them happened). Looking back at your predictions and seeing if the results are what you should expect is called calibration ( example ). In the last panel, it is shown that Cueball anticipated this lack of understanding, so he plays pre-recorded audio of his prediction for the conversation. The title text says that these people are gullible enough to the point that they would accept a disadvantageous bet. However, it also says that the probability that they might not actually go through with paying the bet if they lose brings into question whether to propose the bet is actually worth it. Randall has previously made allusions to betting on fallaciously claimed probabilities in comics such as 1132: Frequentists vs. Bayesians and 955: Neutrinos . The comic doesn't rule out the possibility that event A and event B aren't directly related. For example, it is more likely to flip a coin and get a head than to roll a 6-sided die and get a 6. This is a fairly pointless observation in most cases, except perhaps if one is trying to explain the probability of an unfamiliar event by comparison with something very familiar. At the time of writing, the 2020 United States presidential and congressional elections are less than a month away. This is a time when polls showing one or the other candidate leading are common, and may be misinterpreted to mean that the candidate is certain to win. Additionally, after the 2016 election saw Donald Trump, the trailing candidate in the polls, winning, many also interpreted this to mean that the polls were useless and/or wrong, or even go beyond this and take an adverse poll prediction as a perversely authoritative indication that the exact opposite result (which they would favour) is now a certainty. Cueball has previously shown an interest in U.S. election polling, for example in 500: Election . In early October, famous statistician Nate Silver explained on his podcast "Model Talk" that, according to his model, Donald Trump had a 17% chance of winning reelection in 2020. That seems low, but it's a one in six chance, the odds of Russian roulette, the practice of shooting oneself in the head with a six-bullet barreled pistol with only one chamber loaded: it only has one chance in six to kill the person doing it. Would anyone in their right mind play Russian roulette? The answer he was implying was no. This illustrates how one chance in six is very real. While 17% seems low, it can absolutely happen. [White Hat and Cueball standing next to each other. Cueball has his palm out.] Cueball: Event A is more likely than Event B. [White Hat touches chin thoughtfully] White Hat: So you're saying that Event A will happen. Cueball: No, Event B could also happen. [A frameless panel] White Hat: So you're saying it's 50/50. Cueball: No, it's definitely not 50/50. [Cueball produces a phone] White Hat: Sounds like you have no idea what will happen. Cueball: And yet I knew exactly how this conversation would go. Here, listen: [Cueball clicks a button on his phone] *Click* Phone: Then you'll say, "So it's 50/50"

Election Screen Time

Election Screen Time

https://www.xkcd.com/2371

https://www.explainxkcd.com/wiki/index.php/2371:_Election_Screen_Time

[Cueball is looking at his phone screen time report. The screen appears above his head] Screen Time Report Staying informed about politics like a good civic-minded person [tiny blue bar] 26m Reading election updates that won't affect your actions in any way but slightly improve your knowledge about what's going to happen in a few weeks [really extremely long blue bar-chart bar] 9h14m

Cueball has an app on his phone which informs him of the time spent using it for various purposes. These are typically used to monitor one's own, or maybe one's teenage child's, (over)use of games, social media apps, general browsers, etc., and highlight any surprising issues. It is unclear whether this is: a specific analyser, that somehow identifies just this narrow subset of uses; a more general app, currently filtered to give information on just these two politics-related interactions via some complex heuristic method; or he actually does nothing but these two classifiable things, on this particular device. Whichever is the case, it is currently displaying and comparing just two curiously detailed statistics - the time used staying informed about politics, and the time he has spent reading election updates - and nothing else. The total time recorded would be a large slice of someone's typical day, if the report is for the last 24 hours, but is overwhelmingly dominated by the latter activity whatever the duration covered. The comic reflects that most people spend a lot of time consuming news speculating about who will win the upcoming election, even though reading these "updates" will have no impact on the election because people are unlikely to change their minds because of them. People spend very little time researching information that will allow them to make informed decisions about voting, which is an important civic duty. In addition, a recent article in The Atlantic said that " Reading Too Much Political News Is Bad for Your Well-Being ". The title text suggests regret about the time spent consuming political news, possibly reflecting the sentiment that the 2020 United States presidential election has been especially divisive with little productive dialogue. The title text might also be a reference to the movie Airplane! (directly referencing the 1957 movie Zero Hour! ) where one of the most popular gags is when Steve McCroskey first says "Looks like I picked the wrong week to quit smoking", then "Looks like I picked the wrong week to quit amphetamines", "Looks like I picked the wrong week to quit sniffing glue" and so on. Randall has also mentioned "screen time apps" in 2223: Screen Time . Randall has previously remarked on poor time allocation in 1445: Efficiency , in which he admits that he reduces his overall efficiency by spending too much time figuring out which approach to a problem was more efficient. In 2282: Coronavirus Worries , he indicated that worrying about other people's actions is much less healthy (although unfortunately more common) than looking after your own health. [Cueball is looking at his phone screen time report. The screen appears above his head] Screen Time Report Staying informed about politics like a good civic-minded person [tiny blue bar] 26m Reading election updates that won't affect your actions in any way but slightly improve your knowledge about what's going to happen in a few weeks [really extremely long blue bar-chart bar] 9h14m

Dialect Quiz

Dialect Quiz

https://www.xkcd.com/2372

https://www.explainxkcd.com/wiki/index.php/2372:_Dialect_Quiz

[Box with title at the top] Dialect Quiz [Smaller subtitle underneath] Compare answers with your friends! [Quiz is divided into two columns. Answers to questions are indicated by a letter followed by a closed parentheses, such as A). These letters are greyed out] [Column 1:] How do you address a group of two or more people? A) You B) Y'all C) I have not been around two or more people for so long that I can't remember How do you pronounce "Penelope"? A) Rhymes with "Antelope" B) Rhymes with "Develop" What do you call the scientific field that studies the stars? A) Astrology B) Agronomy C) Cosmetology How do you pronounce "genre"? A) Gone-ra B) Juh-neer C) Jen-er-uh You pronounce "Google" with a high-pitched yelp on the... A) First syllable B) Second syllable What do you call the thing on the wall at school that you drink water from? A) Gutter pipe B) Drainpipe How do you pronounce the name for a short silent video file? A) Animated give B) Animated gift What do you call the baseball-sized garden bugs that, when poked, glow brightly and emit a warbling scream? A) What? B) Lawn buddies [Column 2:] What do you call the misleading lines painted by disgruntled highway workers to trick cars into driving off the road? A) Prank lines B) Devil's Marks C) Fool-me lines D) Fauxguides E) Delaware lines What do you call the blue-green planet in the outer Solar System? A) Uranus B) Neptune What do you call this tool? [Image of a claw hammer] A) Banger B) Nail axe C) Wood mage wand D) I'm familiar with this tool but have no specific word for it E) I have never seen it before What do you call a long sandwich with meats and lettuce and stuff? A) A long sandwich with meats and lettuce and stuff B) A longwich C) A salad hot dog What do you call the scaly many-legged animal often found in attics? A) Lightbulb eater B) I have no special name for them C) I've never looked in my attic What do you say when someone around you sneezes? A) "What was that?" B) "Oh, wow." C) [Quietly] "Yikes."

This comic is a parody of online quizzes that offer to compare the user's dialect of American English with others around the country. These quizzes generally contain questions about word usage, names for certain objects, and pronunciations that vary between different regions of the US. There are also quizzes about broader English dialects, but this comic focuses on commonly cited differences between American dialects. The earliest quiz of this type to be widely disseminated online was the Harvard Dialect Survey , conducted in the early 2000s by Bert Vaux and Scott Golder. The survey created maps of the distribution of various word usage (such as pop/soda/coke for a fizzy softdrink) and was a relatively early example of widely shared Internet "viral" content. In 2013, Josh Katz of the New York Times created a new version based on the Harvard survey, which became the Times' most popular content of 2013 and spread the idea to many more people. Many of the questions in this comic directly derive from entries in those surveys. Randall's previous two comics have been about election predictions, leading up to the 2020 US General Presidential Election. A prominent predictor of the election results is Nate Silver, who runs the FiveThirtyEight website. @NateSilver538 posted his results of taking the New York Times version of the survey on October 11, 2020... just three days before this comic was posted. 2371: Election Screen Time specifically suggests that Randall may be spending too much time obsessing over new posts and content from the election predictors. It's coincidental, but likely, that Nate Silver's tweet inspired Randall's post: he was reminded of the 2013 feature from the Times. [Box with title at the top] Dialect Quiz [Smaller subtitle underneath] Compare answers with your friends! [Quiz is divided into two columns. Answers to questions are indicated by a letter followed by a closed parentheses, such as A). These letters are greyed out] [Column 1:] How do you address a group of two or more people? A) You B) Y'all C) I have not been around two or more people for so long that I can't remember How do you pronounce "Penelope"? A) Rhymes with "Antelope" B) Rhymes with "Develop" What do you call the scientific field that studies the stars? A) Astrology B) Agronomy C) Cosmetology How do you pronounce "genre"? A) Gone-ra B) Juh-neer C) Jen-er-uh You pronounce "Google" with a high-pitched yelp on the... A) First syllable B) Second syllable What do you call the thing on the wall at school that you drink water from? A) Gutter pipe B) Drainpipe How do you pronounce the name for a short silent video file? A) Animated give B) Animated gift What do you call the baseball-sized garden bugs that, when poked, glow brightly and emit a warbling scream? A) What? B) Lawn buddies [Column 2:] What do you call the misleading lines painted by disgruntled highway workers to trick cars into driving off the road? A) Prank lines B) Devil's Marks C) Fool-me lines D) Fauxguides E) Delaware lines What do you call the blue-green planet in the outer Solar System? A) Uranus B) Neptune What do you call this tool? [Image of a claw hammer] A) Banger B) Nail axe C) Wood mage wand D) I'm familiar with this tool but have no specific word for it E) I have never seen it before What do you call a long sandwich with meats and lettuce and stuff? A) A long sandwich with meats and lettuce and stuff B) A longwich C) A salad hot dog What do you call the scaly many-legged animal often found in attics? A) Lightbulb eater B) I have no special name for them C) I've never looked in my attic What do you say when someone around you sneezes? A) "What was that?" B) "Oh, wow." C) [Quietly] "Yikes."

Chemist Eggs

Chemist Eggs

https://www.xkcd.com/2373

https://www.explainxkcd.com/wiki/index.php/2373:_Chemist_Eggs

[Cueball and Ponytail face a table with something like a lab stirrer or heater on it, supporting a flat-bottomed and -topped container from which bubbles are rising.] Cueball: How will I know if the reaction fails? Ponytail: You'll smell the sulfides. Cueball: What do those smell like? Ponytail: Sulfurous. Rotten eggs. [A new panel, the table is gone. Cueball is now facing Ponytail.] Cueball: Chemists always compare sulfur to rotten eggs. Cueball: But why would I know that smell? Ponytail: I dunno, It's a common thing! [Ponytail puts her hand out.] Cueball: Is it? My kitchen is messy, but there aren't eggs lying around rotting. Ponytail: You must have smelled one at some point. [Ponytail is now walking right off-panel, away from Cueball. She is clenching her hands and is evidently annoyed] Cueball: Are all chemists' houses full of random raw eggs? Do you toss them over your shoulder for good luck? Ponytail: My house is not full of eggs! Cueball: What do you consider a normal amount of eggs in a house? Cueball: If kids egg your house this Halloween, how will you know?? The quantity of eggs eaten per person in the U.S was estimated at 289.5 in 2019. [1]

In this comic, Ponytail explains to Cueball that if he smells sulfides then the chemistry experiment on which they're working has failed. Ponytail then clarifies that sulfides smell like rotten eggs. The main and most distinct chemical rotten eggs emit is hydrogen sulfide , hence most people who smell them will link the chemical with "rotten egg smell". Cueball replies, however, that he doesn't actually know what rotten eggs smell like, and it's odd that everyone uses that as a comparison. This is a result of changing times — decades ago, when the 'rotten eggs' descriptor became commonplace in chemistry education at high schools and universities, rotten eggs were indeed common enough that cooks avoided adding eggs directly to other ingredients, lest the rotten egg, not detected until after it was too late, force the cook to discard everything and start over. Vastly improved farming, shipping, and marketing practices have made the rotten egg vanishingly rare, at least at supermarkets in the USA. Moreover, much greater recognition of the health hazards of hydrogen sulfide means that, due to various occupational safety precautions, opportunities for sniffing the gas have become scarce, and usually engender swift reactions such as building evacuation. Thus, the comparison has outlived the circumstances that spawned it, and chemistry teachers parrot a line they learned as students, which is no longer relevant to the students' experience. Cueball then takes the disconnect between the trope and his experience and pushes it for all it's worth. This could be taken as symbolic of people who spot such discordances and blow them out of proportion to troll others, in which case, Cueball has most definitely succeeded, based on how Ponytail reacts — she is clenching her fists in anger as she leaves the conversation, presumably to avoid further irritation. (Perhaps she smells eggs often from the people in 382: Trebuchet !) Some of Cueball 's questions suggest that chemists use eggs in place of other items. For example, the superstitious may react to a spilling of salt by picking it up and throwing it over their left shoulder, ostensibly as an attempt to blind the Devil. Another relates to the upcoming night before Halloween event called " Mischief Night ", where kids are known to throw eggs at houses. Cueball asks Ponytail how she will know if this has happened, as he thinks she keeps an unusually large number of eggs in her house. Even though rotten eggs (and hydrogen sulfide in general) are much less common nowadays, many fuel gases are mixed with odorant compounds to signal that a leak is happening; even if the user might be unfamiliar with "rotten eggs" specifically, a large amount of unpleasant odor still works as an alarm that something bad is happening. People who use natural gas or propane stoves should be familiar with the similarly rotten smell of methanethiol , ethanethiol , and/or tert-butylthiol (the "-SH" thiol group is a common feature of many pungent odors, including garlic and skunk spray). Some mineral springs and other natural water sources also contain sulfides and have a strong sulfide odor and flavor; they are sometimes referred to as "sulfur springs". The title text makes a joke about how often chemists use the comparison, saying that they use a rotten egg smell as the baseline and that a lack of the smell is a distinct one. Given the health hazards of hydrogen sulfide and the regulations now enforced in recognition of those hazards, the chemistry teacher probably doesn't often experience the smell either. Since hydrogen sulfide deadens the sense of smell, taking this smell as a 'baseline' is improbable and potentially dangerous, and it's unfortunate that the title text makes this suggestion. [Cueball and Ponytail face a table with something like a lab stirrer or heater on it, supporting a flat-bottomed and -topped container from which bubbles are rising.] Cueball: How will I know if the reaction fails? Ponytail: You'll smell the sulfides. Cueball: What do those smell like? Ponytail: Sulfurous. Rotten eggs. [A new panel, the table is gone. Cueball is now facing Ponytail.] Cueball: Chemists always compare sulfur to rotten eggs. Cueball: But why would I know that smell? Ponytail: I dunno, It's a common thing! [Ponytail puts her hand out.] Cueball: Is it? My kitchen is messy, but there aren't eggs lying around rotting. Ponytail: You must have smelled one at some point. [Ponytail is now walking right off-panel, away from Cueball. She is clenching her hands and is evidently annoyed] Cueball: Are all chemists' houses full of random raw eggs? Do you toss them over your shoulder for good luck? Ponytail: My house is not full of eggs! Cueball: What do you consider a normal amount of eggs in a house? Cueball: If kids egg your house this Halloween, how will you know?? The quantity of eggs eaten per person in the U.S was estimated at 289.5 in 2019. [1]

10,000 Hours

10,000 Hours

https://www.xkcd.com/2374

https://www.explainxkcd.com/wiki/index.php/2374:_10,000_Hours

[Cueball is staring at his phone. A report from the phone is shown above his head] If you buy into the "10,000 hours" thing, you are now a world-class expert! [Caption below comic] My screen time reports have started trying to put a positive spin on things.

This comic references a common refrain that one must do something for 10,000 hours to become an expert on it. The linked article states: Popular smartphone operating systems automatically record the amount of time the user spends using their phone, broken down by time spent in each app. This feature is supposed to allow users to analyze their own habits. On iOS, this feature is called Screen Time . On Android, it is called Digital Wellbeing . In this comic, Cueball 's phone tells him that, assuming that the 10,000-hour idea is correct, he is now a master of a task, because of the amount of time he has spent on his phone. The 10,000-hour refrain usually pertains to the arts or sports, because they require a certain level of skill; learning to spend time on one's phone does not require this level of training [ citation needed ] , so this stretch of time does not bring Cueball closer to achieving any goal. Furthermore, it is not clear exactly what task (or possibly tasks) Cueball is supposed to have mastered. Randall often pokes fun at his extensive screen time, such as in 2223: Screen Time . Cueball's phone wants to delicately approach the topic so as not to make Cueball feel bad, so the euphemism about expertise is meant to distract him from realizing how much time he actually spends on his phone. Also, the phone tells Cueball that he was become a "world-class expert", when really he is just someone who checks his phone way too much. It is interesting that his phone decides to be kind to him, even when he has neglected it before ( 1668: Singularity ). The title text refers to the fact that people eat a lot, 1-2 hours a day , though not all of this time is spent chewing. At the time of this comic's publication, Randall was just over 36 years old (13,151 days), so he has spent a large amount of time eating, well over 10,000 hours. It could also be a reference to the comic strip Calvin and Hobbes, in which Calvin refers to routines he has created to improve at chewing. [Cueball is staring at his phone. A report from the phone is shown above his head] If you buy into the "10,000 hours" thing, you are now a world-class expert! [Caption below comic] My screen time reports have started trying to put a positive spin on things.

Worst Ladder

Worst Ladder

https://www.xkcd.com/2375

https://www.explainxkcd.com/wiki/index.php/2375:_Worst_Ladder

[Ponytail, Cueball, Hairy and Hairbun are sitting around a boardroom table. Megan is giving a presentation and pointing to a chart behind her.] Megan: Our entertainment division is failing. We can't compete with free content. [A frameless panel. Only Megan is shown, with her pointer to her side.] Off-panel voice: Where are they going? YouTube? TikTok? Megan: No. [Zoomed in on Megan.] Megan: The Google Images search results for worst ladder . Off-panel voice: Huh? Off-panel voice: Let me see ... [Ponytail and Cueball are looking at one laptop, and Hairy and Hairbun are looking at a second. Megan has her arms out in front of her, frustrated.] Ponytail: Yikes, look at this one! The stepladder is balanced on -- Hairy: Wow, they tied a ladder to -- Hairbun: Ooh, check out the -- Megan: No! Searching Google for "worst ladder" at the time the comic was posted allows observing ladders that are comically unsafe or poorly designed (see sample results from shortly after the comic was posted ). It is worth noting that, while normally it does not undergo much change, the "worst ladder" page will likely now contain a barrage of results related to this xkcd comic, as happened with 369: Dangers . This influence is similar to the Slashdot effect . For reference, at the time of posting (0:00 UTC), the comic was the 30th Google image result. From about 0:20 to 1:15 UTC, it was the 18th result; by 1:30 UTC, it had become the third result. Searching Google for "worst ladder -xkcd" yields better results, but some xkcd is still there.

An always present concern of media industries is consumers shifting tastes or indeed abandoning a medium altogether (such as print newspapers or in-person theaters). This strip depicts one such scenario prompting a meeting to discuss the problem. The other attendees suspect the consumers are simply shifting to an online platform, but Megan reveals they are instead shifting towards image search results. Of course, during the age of the internet, there are many sources of free entertainment. YouTube and TikTok provide examples of these services, as practically anyone can choose from a tremendous variety of content. Therefore, this abundance of free content hurts services that require money to see their content, particularly when this content does not have any factors that make it inherently more appealing than the free services. The Quibi paid service shut down, just 6 months after it opened, on the same day that this comic appeared. The joke here is that instead of YouTube or TikTok, possible customers are going to the Google Image search page for "worst ladder" . Even the meeting participants are entranced by it, so the meeting devolves into everyone showing their favorites to each other. Searching for images is an unorthodox source of entertainment, frequently only seen when searching for memes (this, in fact, is how Know Your Meme gauges interest in a meme). Depending on your relationship with Google's personalization algorithms, image results may change up between different people or different views, or remain roughly stagnant from day to day (contrasted with other services that contain new posts nearly every second), and the quality of any Google Images page will decline with scrolling. Therefore, an image search results page is not a sustainable source of entertainment [ citation needed ] , and may be unlikely to compete with the service in this comic. Search results currently tend to vary widely from person to person, as Google uses the user's search history, IP address, and location to try to find the most relevant result for each person, even if they are not logged in. This provides social opportunities around searching, sometimes exploited by social media posts (which may be how Megan originally found out). The title text explains that the company actually decided to use the idea, and created a subscription service for these images. The idea was a success and was indeed very lucrative. They then tried selling actual "worst ladders", or "worst ladders"-themed merchandise at a hardware store, thinking that people who enjoy looking at others' mistakes would also enjoy making that mistake themselves, but this tie-in ended up costing them as much money as they made from the subscriptions (if the word "disastrous" is meant literally, there may have been injuries and liability lawsuits involved). [Ponytail, Cueball, Hairy and Hairbun are sitting around a boardroom table. Megan is giving a presentation and pointing to a chart behind her.] Megan: Our entertainment division is failing. We can't compete with free content. [A frameless panel. Only Megan is shown, with her pointer to her side.] Off-panel voice: Where are they going? YouTube? TikTok? Megan: No. [Zoomed in on Megan.] Megan: The Google Images search results for worst ladder . Off-panel voice: Huh? Off-panel voice: Let me see ... [Ponytail and Cueball are looking at one laptop, and Hairy and Hairbun are looking at a second. Megan has her arms out in front of her, frustrated.] Ponytail: Yikes, look at this one! The stepladder is balanced on -- Hairy: Wow, they tied a ladder to -- Hairbun: Ooh, check out the -- Megan: No! Searching Google for "worst ladder" at the time the comic was posted allows observing ladders that are comically unsafe or poorly designed (see sample results from shortly after the comic was posted ). It is worth noting that, while normally it does not undergo much change, the "worst ladder" page will likely now contain a barrage of results related to this xkcd comic, as happened with 369: Dangers . This influence is similar to the Slashdot effect . For reference, at the time of posting (0:00 UTC), the comic was the 30th Google image result. From about 0:20 to 1:15 UTC, it was the 18th result; by 1:30 UTC, it had become the third result. Searching Google for "worst ladder -xkcd" yields better results, but some xkcd is still there.

Curbside

Curbside

https://www.xkcd.com/2376

https://www.explainxkcd.com/wiki/index.php/2376:_Curbside

[Beret Guy talking on a cell phone. The response from the person on the phone is in a jagged bubble.] Beret Guy: Hi, is this the shop that sells cursed items but when you try to return them the shop is gone? Phone: Yes, how can I help you? [A frameless panel. Beret Guy still talking on the phone] Beret Guy: Do you do curbside pickup? I wanted to buy a cursed amulet that angers ghosts, and some groceries. Phone: No, but it's okay, we wear masks. [Zoomed in on other side of Beret Guy's face] Beret Guy: So you can't bring stuff out? Phone: I'm afraid not. Beret Guy: But it's so stuffy in there! [The callee's response is on the top of the panel. Beret Guy is now holding his phone in front of him, ready to end the call.] Phone: Why not think of the virus as part of the amulet's curse? Beret Guy: Excuse me!? I'm trying to buy some bread and do battle with ghosts, not endanger my family and friends in a pandemic! Beret Guy: I will take my business elsewhere.

This comic is another in a series of comics related to the COVID-19 pandemic . Beret Guy is making contact with a shop that sells cursed items, only to vanish when the customer tries to return the product . He has previously mentioned doing most of his shopping (including groceries) at such locations in 1772: Startup Opportunity , and visited one (possibly the same one) several months earlier in 2332: Cursed Chair . That visit ended with him trying to stop the COVID-19 pandemic by destroying the cursed chair, but evidently he either failed to destroy the chair (which claimed to be immortal) or found that doing so didn't halt the pandemic. (Apparently Beret Guy has visited this same store before, since he says that "it's so stuffy in there", but has not attempted to return any of his purchases, since the store has not disappeared yet. Or perhaps it is simply nonexistent when someone is trying to return something.) After confirming that he has the right number, Beret Guy asks if the cursed store does curbside pickup, as he intends to place an order for bread and a cursed amulet, but does not wish to go inside during the pandemic. Many grocery stores have started offering such services, allowing a customer to place an order over the phone or online, then receive it outside the store, thus minimizing the interaction with store staff or other customers. Closed spaces are understood to pose a greater risk of contagion than the outdoors, where wind and sun can mitigate airborne viral particles. The store's contact replies that no, they do not offer curbside pickup, but tries to assure Beret Guy that all employees at the location wear masks. (They might be wearing haunted Halloween masks .) When Beret Guy expresses disappointment at the revelation, complaining about the stuffy air of the shop, the contact advises him to consider the virus as part of the curses that come with their products. Beret Guy gets angry at this -- apparently, he's okay with buying cursed items, but not exposing himself to unacceptable risks of catching COVID-19. Beret Guy promptly proclaims that he will not be doing business with the location if they are going to showcase such an attitude towards the pandemic. It's unclear how he will find another store with similar unusual characteristics, although it has been mentioned that there is an entire industry of these stores. Beret Guy mentions that he wants to buy an amulet in order to 'do battle with ghosts', which is not an ordinary thing to do given that most people cannot interact directly with ghosts. [ citation needed ] Perhaps he has a ghost-fighting weapon that he has also bought from the shop, although a more likely explanation (given Beret Guy's peculiarity) seems that he is somehow able to engage in martial combat with them. A common argument for how ghosts can exist is that they are in another dimension; given that Beret Guy has extra dimensions in his bones ( 2310: Great Attractor ), he might appear as a skeleton warrior in the ghosts' dimension. Thus, being able to battle ghosts would be one of the many strange powers of Beret Guy . It is also unclear why Beret Guy specifically wants to anger the ghosts. He also mentions that he is there to buy groceries, which is rather ordinary in contrast to the previous request. This is another example of Beret Guy's seemingly oblivious view of the world, putting the purchase of a ghostly amulet on par with buying bread. The title text explains that contact tracers have been attempting to visit the store to figure out who else has been working or shopping there, which suggests that people may have been exposed to COVID there. However, presumably because of the peculiar nature of the store, a notable number of the contact tracers have not returned from visiting it, leading the state to create a tracing program to find the missing contact tracers. The joke here is that the contact tracers must now be traced by another tracing program. This same kind of recursivity of tracking tracers has been previously explored for finding finders and incinerating incinerators . [Beret Guy talking on a cell phone. The response from the person on the phone is in a jagged bubble.] Beret Guy: Hi, is this the shop that sells cursed items but when you try to return them the shop is gone? Phone: Yes, how can I help you? [A frameless panel. Beret Guy still talking on the phone] Beret Guy: Do you do curbside pickup? I wanted to buy a cursed amulet that angers ghosts, and some groceries. Phone: No, but it's okay, we wear masks. [Zoomed in on other side of Beret Guy's face] Beret Guy: So you can't bring stuff out? Phone: I'm afraid not. Beret Guy: But it's so stuffy in there! [The callee's response is on the top of the panel. Beret Guy is now holding his phone in front of him, ready to end the call.] Phone: Why not think of the virus as part of the amulet's curse? Beret Guy: Excuse me!? I'm trying to buy some bread and do battle with ghosts, not endanger my family and friends in a pandemic! Beret Guy: I will take my business elsewhere.

xkcd Phone 12

xkcd Phone 12

https://www.xkcd.com/2377

https://www.explainxkcd.com/wiki/index.php/2377:_xkcd_Phone_12

[The comic shows two smartphones: one taller and wider than the other. ] [Labels to the left of the larger smartphone:] [Labels to the right of the larger smartphone:] [Labels to the right of the smaller smartphone:] [Text below the phone:] The xkcd Phone 12* and 12 Max** *Standard **For people named Max "The only phone you'll ever own"®™

This is the "12th" (actually the 8th) in the ongoing xkcd Phone series in which Randall explains his new joke phone designs with many strange and useless features. It is also a reference to the recently released iPhone 12 . However, there have only been 8 comics released, with the previous two being 2000: xkcd Phone 2000 and 1889: xkcd Phone 6 . The note about the xkcd Phone 12 and the xkcd Phone 12 Max (only for people named Max) is a joke about the different models of iPhone 12: iPhone 12, iPhone 12 Mini, iPhone 12 Pro and iPhone 12 Pro Max. The xkcd Phone 12 Max would be expected to have a larger screen, but it seems that this phone is also only for people with the name Max. If the phones are respectively placed, Max's (Maxes'?) phone is the smaller of the two models. The slogan '"The only phone you'll ever own"' could be interpreted as something of a threat, which is believable given some of the purported features. The slogan has the "registered trademark" symbol, with that symbol supposedly itself trademarked, which is highly unlikely. It is similar to the phrase "The last suit you'll ever wear" , describing the black suits worn by the Men In Black in the movie of the same name. Multiple features are labelled on the phone that are common when advertising other products, but highly unusual in mobile phones, for comedic effect: The title text mentions xkcd phone OS updates, including: [The comic shows two smartphones: one taller and wider than the other. ] [Labels to the left of the larger smartphone:] [Labels to the right of the larger smartphone:] [Labels to the right of the smaller smartphone:] [Text below the phone:] The xkcd Phone 12* and 12 Max** *Standard **For people named Max "The only phone you'll ever own"®™

Fall Back

Fall Back

https://www.xkcd.com/2378

https://www.explainxkcd.com/wiki/index.php/2378:_Fall_Back

[Cueball is looking at his phone.] Cueball: It's 8 PM. Exactly six days until the polls close here. [Megan walks in from Cueball's left, holding up a finger. Cueball has lowered his phone.] Megan: Six days and one hour. Cueball: Oh right, fall back. Cueball: Ugh. [Megan holds out her arms.] Megan: Personally, I think it's great. Megan: Don't you want this moment to last as long as possible? [Close up on Megan.] Megan: My pandemic anxiety and election anxiety have finally fused. Megan: I have ascended. Megan: I get breaking news alerts in my dreams. [Back to Cueball and Megan.] Cueball: I don't think the endless 24 hour news cycle has been good for either of us. Megan: Well, then I have good news about Sunday! Cueball: Ughhh.

Daylight saving time ends in the United States at 2 a.m. on the first Sunday in November, when 2 a.m. becomes 1 a.m. Election Day in the United States is on the Tuesday after the first Monday in November. In 2020, Nov. 1 is Sunday, so the shift from Daylight Saving Time to Standard Time will happen two days before the 2020 election . This has the effect of making Sunday, Nov. 1 a 25-hour day. The switchover is sometimes referred to mnemonically as "fall back," with its springtime counterpart (a day of 23 hours) being "spring forward" as mentioned in 1655: Doomsday Clock . At the beginning of the comic, Cueball incorrectly calculates the time until the election day polls close (this varies from state to state); in the second panel, Megan reminds him about falling back. She goes on to possibly sarcastically treasure this extended moment, one more hour to experience the bitter election cycle and the COVID-19 pandemic . Megan describes herself as dissociating here, and it is possible she is actually treating these emergencies as good now, instead of bad. The behavior could be seen as an indirect demand for the situation to change, a demonstration that she may lose her sanity further if it does not. Cueball hears how intense she is saying her experience is, and says he thinks they've both spent too much time engaging with the news (a sentiment echoed from other recent xkcd comics, like 2371: Election Screen Time and possibly 2374: 10,000 Hours ). When he mentions the 24-hour news cycle , Megan corrects him again, as Sunday will be a 25 -hour news cycle. The title text refers to a popular sentiment that the issues and emotions raised in the 2016 United States presidential election were not settled when the election was over and have continued unabated since then. Even though the election itself was held in November 2016, the primary candidates officially announced their campaigns in early 2015; thus, 2020 is the sixth year since that campaign season opened. The implication could be that the whole nation, or at least Randall's community of political followers, has had to be in an altered state of consciousness to handle the past six years. It could also be a reference to ongoing strong campaigning, in excess of what people have seen in the past. [Cueball is looking at his phone.] Cueball: It's 8 PM. Exactly six days until the polls close here. [Megan walks in from Cueball's left, holding up a finger. Cueball has lowered his phone.] Megan: Six days and one hour. Cueball: Oh right, fall back. Cueball: Ugh. [Megan holds out her arms.] Megan: Personally, I think it's great. Megan: Don't you want this moment to last as long as possible? [Close up on Megan.] Megan: My pandemic anxiety and election anxiety have finally fused. Megan: I have ascended. Megan: I get breaking news alerts in my dreams. [Back to Cueball and Megan.] Cueball: I don't think the endless 24 hour news cycle has been good for either of us. Megan: Well, then I have good news about Sunday! Cueball: Ughhh.

Probability Comparisons

Probability Comparisons

https://www.xkcd.com/2379

https://www.explainxkcd.com/wiki/index.php/2379:_Probability_Comparisons

[Large heading, centered.] Probability Comparisons [Left column.] 0.01% You guess the last four digits of someone's social security number on the first try 0.1% Three randomly chosen people are all left-handed 0.2% You draw 2 random Scrabble tiles and get M and M You draw 3 random M&Ms and they're all red 0.3% You guess someone's birthday in one try. 0.5% An NBA team down by 30 at halftime wins You get 4 M&Ms and they're all brown or yellow 1% Steph Curry gets two free throws and misses both LeBron James guesses your birthday, if each guess costs one free throw and he loses if he misses 1.5% You get two M&Ms and they're both red You share a birthday with a Backstreet Boy 2% You guess someone's card on the first try 3% You guess 5 coin tosses and get them all right Steph Curry wins that birthday free throw game 4% You sweep a 3-game rock paper scissors series Portland, Oregon has a white Christmas You share a birthday with two US Senators 5% An NBA team down 20 at halftime wins You roll a natural 20 6% You correctly guess someone's card given 3 tries 7% LeBron James gets two free throws and misses both 8% You correctly guess someone's card given 4 tries 9% Steph Curry misses a free throw 10% You draw 5 cards and get the Ace of Spades There's a magnitude 8+ earthquake in the next month 11% You sweep a 2-game rock paper scissors series 12% A randomly-chosen American lives in California You correctly guess someone's card given 6 tries You share a birthday with a US President 13% A d6 beats a d20 An NBA team down 10 going into the 4th quarter wins You pull one M&M from a bag and it's red 14% A randomly drawn scrabble tile beats a d6 die roll 15% You roll a d20 and get at least 18 16% Steph Curry gets two free throws but makes only one 17% You roll a d6 die and get a 6 18% A d6 beats or ties a d20 19% At least one person in a random pair is left-handed 20% You get a dozen M&Ms and none of them are brown 21% St. Louis has a white Christmas 22% An NBA team wins when they're down 10 at halftime 23% You get an M&M and it's blue You share a birthday with a US senator 24% You correctly guess that someone was born in the winter 25% You correctly guess that someone was born in the fall You roll two plain M&Ms and get M and M. 26% You correctly guess someone was born in the summer 27% LeBron James misses a free throw 32% Pittsburgh has a white Christmas 33% A randomly chosen Star Wars movie (Episodes I-IX) has "of the" in the title You win the Monty Hall sports car by picking a door and refusing to switch You win rock paper scissors by picking randomly 34% You draw five cards and get an ace 35% A random Scrabble tile is one of the letters in "random" [Right column.] 39% LeBron James gets two free throws but misses one 40% A random Scrabble tile is a letter in "Steph Curry" 46% There's a magnitude 7 quake in LA within 30 years 48% Milwaukee has a white Christmas A random Scrabble tile is a letter in Carly Rae Jepsen 50% You get heads in a coin toss 53% Salt Lake City has a white Christmas 54% LeBron James gets two free throws and makes both 58% A random Scrabble tile is a letter in "Nate Silver" 60% You get two M&Ms and neither is blue 65% Burlington, Vermont has a white Christmas 66% A randomly chosen movie from the main Lord of the Rings trilogy has “of the” in the title twice 67% You roll at least a 3 with a d6 71% A random Scrabble tile beats a random dice roll 73% LeBron James makes a free throw 75% You drop two M&Ms and one of them ends with the "M" up so it's clear they're not Skittles 76% You get two M&Ms and neither is red 77% You get an an M&M and it's not blue 78% An NBA team wins when they're up 10 at halftime 79% St. Louis doesn't have a white Christmas 81% Two random people are both right-handed 83% Steph Curry gets two free throws and makes both 85% You roll a d20 and get at least a 4 87% An NBA team up by 10 going into the 4 th quarter wins Someone fails to guess your card given 7 tries 88% A randomly chosen American lives outside California 89% You roll a 3 or higher given two tries 90% Someone fails to guess your card given 5 tries 91% You incorrectly guess that someone was born in August Steph Curry makes a free throw 92% You guess someone's birth month at random and are wrong 93% Lebron James makes a free throw given two tries 94% Someone fails to guess your card given 3 tries 95% An NBA team wins when they're up 20 at halftime 96% Someone fails to guess your card given 2 tries 97% You try to guess 5 coin tosses and fail 98% You incorrectly guess someone's birthday is this week 98.5% An NBA team up 15 points with 8 minutes left wins 99% Steph Curry makes a free throw given two tries 99.5% An NBA team that's up by 30 points at halftime wins 99.7% You guess someone's birthday at random and are wrong 99.8% There's not a magnitude 8 quake in California next year 99.9% A random group of three people contains a right-hander 99.99% You incorrectly guess the last four digits of someone's social security number 99.9999999999999995% You pick up a phone, dial a random 10-digit number, and say 'Hello Barack Obama, there's just been a magnitude 8 earthquake in California!" and are wrong 0.00000001% You add "Hang on, this is big — I'm going to loop in Carly Rae Jepsen", dial another random 10-digit number, and she picks up [In light grey colour and in the lower left corner there is text.] Sources: https://xkcd.com/2379/sources/

This is a list of probabilities for different events. There are numerous recurring themes, of which the most common are free throws (13 entries), birthdays (12), dice (12, split about evenly between 6-sided (d6) and 20-sided (d20) types), M&M candies (11), playing cards (9), NBA basketball mid-game victory predictions (9), Scrabble tiles (7), coins (7), white Christmases (7), and the NBA players Stephen Curry and LeBron James (7 each). Themes are variously repeated and combined, for humorous effect. For instance, there are entries for both the probability that St. Louis will have a white Christmas (21%) and that it will not (79%). Also given is the 40% probability that a random Scrabble tile will contain a letter from the name "Steph Curry". There are 80 items in the list, the last two of which devolve into absurdity - perhaps from the stress of preparing the other 78 entries. The list may be an attempt to better understand probabilistic election forecasts for the 2020 United States presidential election , which was four days away at the time this comic was published and had also been alluded to in 2370: Prediction and 2371: Election Screen Time . Statistician and psephologist Nate Silver is referenced in one of the list items. On the date this cartoon was published, Nate Silver's website FiveThirtyEight.com was publishing forecast probabilities of Donald Trump and Joe Biden winning the US Presidential election. On 31 October 2020, the forecast described the chances of Donald Trump winning as "roughly the same as the chance that it’s raining in downtown Los Angeles. It does rain there. (Downtown L.A. has about 36 rainy days per year, or about a 1-in-10 shot of a rainy day.)" A day previously, when the chances were 12%, the website had also described Trump's chances of winning as "slightly less than a six sided die rolling a 1". The probabilities are calculated from these sources , as mentioned in the bottom left corner. The title text refers to the song " Call Me Maybe " by Carly Rae Jepsen (cited twice in the list). "MAYBE" is emphasized, perhaps because the probability of getting her phone number correct, as in the last item in the list, is very low. The capitalization could also be a reference to Scrabble tiles, as was previously mentioned in association with Carly Rae Jepsen. In the original comic, "outside" in the 88% probability section is spelled incorrectly as "outide". In addition, the 39% section had "two free throw" instead of "throws". The (seemingly unimportant) odds of LeBron James' versus Stephen Curry's free throws and names in Scrabble refer to 2002: LeBron James and Stephen Curry . [Large heading, centered.] Probability Comparisons [Left column.] 0.01% You guess the last four digits of someone's social security number on the first try 0.1% Three randomly chosen people are all left-handed 0.2% You draw 2 random Scrabble tiles and get M and M You draw 3 random M&Ms and they're all red 0.3% You guess someone's birthday in one try. 0.5% An NBA team down by 30 at halftime wins You get 4 M&Ms and they're all brown or yellow 1% Steph Curry gets two free throws and misses both LeBron James guesses your birthday, if each guess costs one free throw and he loses if he misses 1.5% You get two M&Ms and they're both red You share a birthday with a Backstreet Boy 2% You guess someone's card on the first try 3% You guess 5 coin tosses and get them all right Steph Curry wins that birthday free throw game 4% You sweep a 3-game rock paper scissors series Portland, Oregon has a white Christmas You share a birthday with two US Senators 5% An NBA team down 20 at halftime wins You roll a natural 20 6% You correctly guess someone's card given 3 tries 7% LeBron James gets two free throws and misses both 8% You correctly guess someone's card given 4 tries 9% Steph Curry misses a free throw 10% You draw 5 cards and get the Ace of Spades There's a magnitude 8+ earthquake in the next month 11% You sweep a 2-game rock paper scissors series 12% A randomly-chosen American lives in California You correctly guess someone's card given 6 tries You share a birthday with a US President 13% A d6 beats a d20 An NBA team down 10 going into the 4th quarter wins You pull one M&M from a bag and it's red 14% A randomly drawn scrabble tile beats a d6 die roll 15% You roll a d20 and get at least 18 16% Steph Curry gets two free throws but makes only one 17% You roll a d6 die and get a 6 18% A d6 beats or ties a d20 19% At least one person in a random pair is left-handed 20% You get a dozen M&Ms and none of them are brown 21% St. Louis has a white Christmas 22% An NBA team wins when they're down 10 at halftime 23% You get an M&M and it's blue You share a birthday with a US senator 24% You correctly guess that someone was born in the winter 25% You correctly guess that someone was born in the fall You roll two plain M&Ms and get M and M. 26% You correctly guess someone was born in the summer 27% LeBron James misses a free throw 32% Pittsburgh has a white Christmas 33% A randomly chosen Star Wars movie (Episodes I-IX) has "of the" in the title You win the Monty Hall sports car by picking a door and refusing to switch You win rock paper scissors by picking randomly 34% You draw five cards and get an ace 35% A random Scrabble tile is one of the letters in "random" [Right column.] 39% LeBron James gets two free throws but misses one 40% A random Scrabble tile is a letter in "Steph Curry" 46% There's a magnitude 7 quake in LA within 30 years 48% Milwaukee has a white Christmas A random Scrabble tile is a letter in Carly Rae Jepsen 50% You get heads in a coin toss 53% Salt Lake City has a white Christmas 54% LeBron James gets two free throws and makes both 58% A random Scrabble tile is a letter in "Nate Silver" 60% You get two M&Ms and neither is blue 65% Burlington, Vermont has a white Christmas 66% A randomly chosen movie from the main Lord of the Rings trilogy has “of the” in the title twice 67% You roll at least a 3 with a d6 71% A random Scrabble tile beats a random dice roll 73% LeBron James makes a free throw 75% You drop two M&Ms and one of them ends with the "M" up so it's clear they're not Skittles 76% You get two M&Ms and neither is red 77% You get an an M&M and it's not blue 78% An NBA team wins when they're up 10 at halftime 79% St. Louis doesn't have a white Christmas 81% Two random people are both right-handed 83% Steph Curry gets two free throws and makes both 85% You roll a d20 and get at least a 4 87% An NBA team up by 10 going into the 4 th quarter wins Someone fails to guess your card given 7 tries 88% A randomly chosen American lives outside California 89% You roll a 3 or higher given two tries 90% Someone fails to guess your card given 5 tries 91% You incorrectly guess that someone was born in August Steph Curry makes a free throw 92% You guess someone's birth month at random and are wrong 93% Lebron James makes a free throw given two tries 94% Someone fails to guess your card given 3 tries 95% An NBA team wins when they're up 20 at halftime 96% Someone fails to guess your card given 2 tries 97% You try to guess 5 coin tosses and fail 98% You incorrectly guess someone's birthday is this week 98.5% An NBA team up 15 points with 8 minutes left wins 99% Steph Curry makes a free throw given two tries 99.5% An NBA team that's up by 30 points at halftime wins 99.7% You guess someone's birthday at random and are wrong 99.8% There's not a magnitude 8 quake in California next year 99.9% A random group of three people contains a right-hander 99.99% You incorrectly guess the last four digits of someone's social security number 99.9999999999999995% You pick up a phone, dial a random 10-digit number, and say 'Hello Barack Obama, there's just been a magnitude 8 earthquake in California!" and are wrong 0.00000001% You add "Hang on, this is big — I'm going to loop in Carly Rae Jepsen", dial another random 10-digit number, and she picks up [In light grey colour and in the lower left corner there is text.] Sources: https://xkcd.com/2379/sources/

Election Impact Score Sheet

Election Impact Score Sheet

https://www.xkcd.com/2380

https://www.explainxkcd.com/wiki/index.php/2380:_Election_Impact_Score_Sheet

Do you know anyone in Arizona? Research shows that reminders from friends and family to vote have a bigger effect on turnout than anything campaigns do. One of the best ways you can help is to scroll through your contacts (or use apps like VoteWithMe) to find people you can check in with to see if they plan to vote or need help doing it. This chart lets you tally the effect of your reminders on the outcome based on who you've contacted and where they live. Election impact score sheet *Multiplier based on 538 presidential vote impact, plus points for senate and local elections In smaller text, to the right of the main score sheet, a duplicate of the score sheet with red tally marks and points is shown Followed by an arrow, pointing to the "Your election impact" total box in the main table, is this text Based on turnout experiments, 10 points on this scale has roughly as much effect on the outcome as one average vote. For every 10 points you tally, it's as if you voted again! Below the main score sheet table [Click for printable version] Share a pic of your score sheet with #Hashtag , and be sure to send a copy to Nate Silver to let him know to include those extra votes in his model!

This comic was published the day before Election day in the United States (November 3, 2020), which features a contentious presidential election between the incumbent, President Donald Trump , and the challenger, former Vice President Joe Biden . The United States does not elect presidents by popular vote, but instead uses an electoral college system, with each state getting a predetermined number of electoral votes, and a majority of electoral votes needed to win an election. The previous presidential election in 2016, which involved Trump and Hillary Clinton , was won by Trump, who lost the popular vote by 2 percentage points, but won the electoral vote 304-227 (270 was needed to win the election). Electoral college votes are distributed based on the number of congressional representatives of each state, with the most populous state, California, receiving 55 votes, and the least populous states which are Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming receiving 3 votes each, along with the District of Columbia, which as of the writing of this comic was not a state. Because the United States Congress has two legislative houses, with only one (the House of Representatives) apportioning representatives to the states based on their percentage of the US population and the other (the Senate) allocating two senators to every state regardless of population, smaller states have a higher ratio of electoral college votes to population than larger states do. Additionally, most states (all but Nebraska and Maine) give all of their electoral college votes to whoever earns the most votes in their state. This means that a small change in the percentage of voters who favor one party's candidate over another within a state doesn't make a difference on the final outcome unless that change tips the scales between the two candidates. Therefore, it's easy to predict the final electoral college votes of many states where one party has a clear lead. Other states, including some of the ones listed by Randall, are considered " swing states ", as they are competitive to both of the two major parties, the Republican Party and the Democratic Party . Together, these factors make voting in some states - "swing states" with smaller populations - much more likely to influence the outcome of the election than others. Randall in this comic is encouraging his readers to " get out the vote " and encourage voting among their friends and family who live in these nineteen states which are most likely to affect the outcome of the election. The rest of the 31 states (and, presumably, the District of Columbia) are grouped under the "all other states" bucket, presumably as their election outcome is "safely" for Biden or Trump. Per many analysts, the state of Pennsylvania is considered an absolute necessity for Trump, and considered very important for Biden. This is why Pennsylvania is weighted the most heavily in Randall's comic. Of course, just because a state may be a clear win for one party does not mean the votes of anyone who votes for the other party are wasted. A higher percentage of voters voting for the losing candidate sends a signal that the state is more competitive than assumed, which forces representatives to compromise and could make future voters more likely to show up because they believe their vote is more likely to matter. Additionally, many "down-ballot" races, like races for governorships, US Congress, state legislatures, and county governments, may be more competitive than the presidential race, and may have just as much or more impact on most people's lives. Randall accounts for some of these local races in deciding how to rank the states on the scoresheet. The text at the bottom says to post your scoresheet with #Hashtag . The "#" symbol (pronounced "hash") denotes a hashtag on platforms like Twitter, used to tag one's post as relating to the topic named following the symbol. However, this hashtag (said out-loud as "Hashtag Hashtag") would relate a post to the topic of hashtags rather than elections or votes, and so for the scoresheet is nonsensical and doesn't describe anything useful. It also refers to Nate Silver's famous election forecast model at FiveThirtyEight . Randall closes by urging people to contact Nate Silver to tell him to adjust his model to account for the added votes they have caused, but as the form doesn't indicate which candidate the filler has voted for or plans to vote for, never mind the people contacted, there's no way for him to know what sort of update to make. Perhaps the flurry of posts bearing the hashtag "#Hashtag" and indicating an effort to increase civic engagement will be a heartwarming surprise on a day that will probably be very busy and stressful for him. The title text explains that even if one thinks that their family and friends always vote, or that their reminder to vote won't work, they should do so anyway because of the chance they may be wrong. As shown in previous comics ( 1756: I'm With Her and others), Randall was a supporter of 2016 candidate Hillary Clinton (who ran against Trump), but this announcement should be equally applicable to supporters of either of the two main candidates in the current presidential race. The comic includes a link for a printable version: https://xkcd.com/2380/election_impact_score_sheet.pdf As for all other states: President Trump won Alabama, Arkansas, Idaho, Indiana, Kentucky, Louisiana, Missouri, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia, and Wyoming; while former Vice President won California, Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Maryland, Massachusetts, New Jersey, New York, Oregon, Rhode Island, Virginia, Vermont, and Washington. Do you know anyone in Arizona? Research shows that reminders from friends and family to vote have a bigger effect on turnout than anything campaigns do. One of the best ways you can help is to scroll through your contacts (or use apps like VoteWithMe) to find people you can check in with to see if they plan to vote or need help doing it. This chart lets you tally the effect of your reminders on the outcome based on who you've contacted and where they live. Election impact score sheet *Multiplier based on 538 presidential vote impact, plus points for senate and local elections In smaller text, to the right of the main score sheet, a duplicate of the score sheet with red tally marks and points is shown Followed by an arrow, pointing to the "Your election impact" total box in the main table, is this text Based on turnout experiments, 10 points on this scale has roughly as much effect on the outcome as one average vote. For every 10 points you tally, it's as if you voted again! Below the main score sheet table [Click for printable version] Share a pic of your score sheet with #Hashtag , and be sure to send a copy to Nate Silver to let him know to include those extra votes in his model!

The True Name of the Bear

The True Name of the Bear

https://www.xkcd.com/2381

https://www.explainxkcd.com/wiki/index.php/2381:_The_True_Name_of_the_Bear

[Megan walks in front the left, looking down at her phone. Cueball and Ponytail are standing next to each other.] Megan: Wow - according to the internet, we don't know the true name of the bear. Cueball: What? [Gretchen McCulloch, drawn with short, curly hair, comes on-panel from the right.] Megan: Apparently there was a superstition that saying its name would summon it. "Bear" and "bruin" mean "the brown one." Its actual name has been lost. Cueball: Wow. Ponytail: Gretchen, is this for real? [Zoom-in on Gretchen.] Gretchen: Well, sort of Gretchen: The Proto-Indo-European root was *rkto- Gretchen: It was lost in the Germanic languages like English, but survived elsewhere, e.g. Greek "arktos" and Latin "ursus" [Back to the second panel, with Megan holding her phone down, Ponytail with her hands in the air, and Gretchen with her hand on her chin.] Megan: So could we figure out what the word would have been in English? Gretchen: Hmm. I mean, we'll never know, but given Germanic sound shifts, a reasonable guess might be "arth"? Ponytail: No!! [The panel zooms in again to Gretchen.] Ponytail (off-panel): Stop! AAAAA! Gretchen: What?? Ponytail (off-panel): Don't say it! [Ponytail is holding her palms out. Megan is no longer in the panel.] Ponytail: What have you done ? Off-panel noise: ROAR Gretchen: Oh Gretchen: Oh no The last comic strip that ended with the words "Oh no" was 2314: Carcinization , which also featured an unfortunate occurrence involving an animal as its punchline when Cueball spontaneously transformed into a crab.

The Canadian Internet linguist Gretchen McCulloch tweeted about the theory that the word for bear became taboo in some branches of Indo-European languages - notably the Germanic one - and it was replaced by euphemisms. In the Germanic branch, the euphemism may have been "the brown one," and thus the modern word "bear" (derived from Germanic "beran") would more literally translate into the color "brown" rather than the animal. The Indoeuropean root for bear is *rkto-, which has been inferred from modern languages that still use a word derived from it. In the comic, McCulloch applies sound shifting laws to it to guess how it would have evolved in English had it not been superseded, but saying it seems to actually summon a bear. Interestingly enough, the hypothesized word “arth” is the same as the Welsh and Cornish for the word “bear.” Welsh belongs to the Celtic language family, which is one of the Indo-European branches that still uses a word derived from *rkto-, as do the Italic (Romance), Greek and Indo-Aryan (Sanskrit) branches, while Germanic, Slavic and Baltic branches abandoned it for different euphemisms. Another Indo-European language where the word for bear is very close to this extrapolation is Armenian, where it's written արջ and pronounced “artch”. The comic does not explain why speakers of Welsh, Cornish, Italic, Greek, Indo-Aryan, and Armenian languages do not summon a bear every time they refer to one. [ citation needed ] Use of true names appears to be highly effective in the xkcd universe, rather like a fairy tale , and it is also a common trope elsewhere. Some say a true name contains clear meaning of who someone or something really is. In 2421: Tower of Babel a linguist that resembles Gretchen from this comic appears. Since that story takes place in biblical time, it is not Gretchen, but obviously this is how linguists look in xkcd from now on. [Megan walks in front the left, looking down at her phone. Cueball and Ponytail are standing next to each other.] Megan: Wow - according to the internet, we don't know the true name of the bear. Cueball: What? [Gretchen McCulloch, drawn with short, curly hair, comes on-panel from the right.] Megan: Apparently there was a superstition that saying its name would summon it. "Bear" and "bruin" mean "the brown one." Its actual name has been lost. Cueball: Wow. Ponytail: Gretchen, is this for real? [Zoom-in on Gretchen.] Gretchen: Well, sort of Gretchen: The Proto-Indo-European root was *rkto- Gretchen: It was lost in the Germanic languages like English, but survived elsewhere, e.g. Greek "arktos" and Latin "ursus" [Back to the second panel, with Megan holding her phone down, Ponytail with her hands in the air, and Gretchen with her hand on her chin.] Megan: So could we figure out what the word would have been in English? Gretchen: Hmm. I mean, we'll never know, but given Germanic sound shifts, a reasonable guess might be "arth"? Ponytail: No!! [The panel zooms in again to Gretchen.] Ponytail (off-panel): Stop! AAAAA! Gretchen: What?? Ponytail (off-panel): Don't say it! [Ponytail is holding her palms out. Megan is no longer in the panel.] Ponytail: What have you done ? Off-panel noise: ROAR Gretchen: Oh Gretchen: Oh no The last comic strip that ended with the words "Oh no" was 2314: Carcinization , which also featured an unfortunate occurrence involving an animal as its punchline when Cueball spontaneously transformed into a crab.

Ballot Tracker Tracker

Ballot Tracker Tracker

https://www.xkcd.com/2382

https://www.explainxkcd.com/wiki/index.php/2382:_Ballot_Tracker_Tracker

[Cueball is sitting behind a desk, pointing at a laptop. White Hat is standing behind him. Crumpled-up papers are strewn across the ground. ] Cueball: And this tab is my ballot tracker tracker, which tracks how quickly other ballot trackers update. White Hat: You should add a tracker for how often you breathe so you don't forget. Cueball: I will breathe when they call it.

This comic was posted 3 days after the 2020 election day in the United States (November 3, 2020). As of the date of posting, the 2020 United States presidential election , between President Donald Trump and former Vice President Joe Biden , still had not been "called" for either candidate by most news outlets ("called" refers to projecting the results of the election). This was atypical for most US presidential elections, which were "called" either on election day or on the morning following. A major reason for the delay in determining the results of the election was the greatly increased use of mail-in ballots , caused by social distancing concerns due to the COVID-19 pandemic. Mail-in ballots in some states were counted after the in-person voting, which caused delays in the vote-counting, and thus the projection of the winner. As of the date of posting, the electoral vote counts - as called by most major news organizations - were 253-214 in favor of Biden, with 270 electoral votes needed to win the election. Six states were considered "too close to call", with no determined winner until more ballots were counted. Biden was winning the popular vote by about 4 million. Cueball in this comic has created an app, doc, or website that tracks in real time how quickly "ballot trackers" update. A ballot tracker is a web page provided by a news organization that reports updated vote counts as they are published by the states. The news organizations use these counts as the major input to the "decision desks", which are their staff who analyze the ongoing vote results to decide when to declare a projected winner for a state. (See "Tracking Which News Outlets Have Called the Presidential Race in Each State" ) Cueball (representing Randall) is anxiously awaiting resolution to the long election season. Not only is he anxiously checking to see if the race has been decided, but he is also predicting how close the race is to being decided by constantly checking the ballot trackers to see how they change, as well as keeping track of which sources of tracking information most quickly show updated information on which to base those predictions. The last line of dialogue in the comic, where Cueball says, "I will breathe when they call it", may refer to the idea that many people " hold their breath " when waiting for an important result, so people may hold their breath until the Presidential race is called. However, since this time around the announcement could have taken days if not weeks longer, literally holding one's breath until the winner was announced would not be possible. [ citation needed ] As it happens, the election was called for Biden the morning after this comic was published, about 3½ days after the election, although Trump was still attempting to challenge the results in court, which would make holding one's breath until all appeals and recounts are complete an even worse idea than if he had conceded. In the title text, Randall wishes good luck to the Democrats in the state of Georgia who are running in later run-off elections. Two Senate seats were being voted on in the state of Georgia in 2020, but no candidate achieved over 50% of the vote in either race. It was highly likely that the runoffs would determine control of the Senate. By law in the state of Georgia, these two races were decided in "runoff" elections, where the top two candidates from each of the races ran against only each other, on January 5, 2021. In the end, both Democrats were elected to the Senate. Randall also wishes good luck to the SREs ( Site Reliability Engineers ) of Google Sheets, an online spreadsheet program, who are in charge of maintaining the Google infrastructure while people like him are constantly refreshing their sheets and pulling data. Randall is comparing Georgia's upcoming "runoff" election to the current election, calling it a "run-on" for how long it is taking. The theme of recursive naming is a recurring one in xkcd, most recently with the "contact tracer tracing program" in 2376: Curbside . [Cueball is sitting behind a desk, pointing at a laptop. White Hat is standing behind him. Crumpled-up papers are strewn across the ground. ] Cueball: And this tab is my ballot tracker tracker, which tracks how quickly other ballot trackers update. White Hat: You should add a tracker for how often you breathe so you don't forget. Cueball: I will breathe when they call it.

Electoral Precedent 2020

Electoral Precedent 2020

https://www.xkcd.com/2383

https://www.explainxkcd.com/wiki/index.php/2383:_Electoral_Precedent_2020

The problem with statements like "No <party> candidate has won the election without <state>" Or "No president has been reelected under <circumstances>" ★ Updated for 2020 ★ [Each statement below has its own panel. The year is in a caption, the precedent is stated by a standing Cueball in the main panel, and the president who broke it is below the panel.] 1788... No one has been elected president before. ...But Washington was. 1792... No incumbent has ever been reelected. ...Until Washington. 1796... No one without false teeth has become president. ...But Adams did. 1800... No challenger has beaten an incumbent. ...But Jefferson did. 1804... No incumbent has beaten a challenger. ...Until Jefferson. 1808... No congressman has ever become president. ...Until Madison. 1812... No one can win without New York. ...But Madison did. 1816... No candidate who doesn't wear a wig can get elected. ...Until Monroe was. 1820... No one who wears pants instead of breeches can be reelected. ...But Monroe was. 1824... No one has ever won without a popular majority. ...J.Q. Adams did. 1828... Only people from Massachusetts and Virginia can win. ...Until Jackson did. 1832... The only presidents who get reelected are Virginians. ...Until Jackson. 1836... New Yorkers always lose. ...Until Van Buren. 1840... No one over 65 has won the presidency. ...Until Harrison did. 1844... No one who's lost his home state has won. ...But Polk did. 1848... As goes Mississippi, so goes the nation. ...Until 1848. 1852... New England Democrats can't win. ...Until Pierce did. 1856... No one can become president without getting married. ...Until Buchanan did. 1860... No one over 6'3" can get elected. ...Until Lincoln. 1864... No one with a beard has been reelected. ...But Lincoln was. 1868... No one can be president if their parents are alive. ...Until Grant. 1872... No one with a beard has been reelected in peacetime. ...Until Grant was. 1876... No one can win a majority of the popular vote and still lose. ...Tilden did. 1880... As goes California, so goes the nation. ...Until it went Hancock. 1884... Candidates named "James" can't lose. ...Until James Blaine. 1888... No sitting president has been beaten since the Civil War. ...Cleveland was. 1892... No former president has been elected. ...Until Cleveland. 1896... Tall Midwesterners are unbeatable. ...Bryan wasn't. 1900... No Republican shorter than 5'8" has been reelected. ...Until McKinley was. 1904... No one under 45 has been elected. ...Roosevelt did. 1908... No Republican who hasn't served in the military has won. ...Until Taft. [The precedent takes up the entire panel this year. Consequently, there is no Cueball.] 1912... After Lincoln beat the Democrats while sporting a beard with no mustache, the only Democrats who can win have a mustache with no beard. ...Wilson had neither. 1916... No Democrat has won while losing West Virginia. ...Wilson did. 1920... No incumbent senator has won. ...Until Harding. 1924... No one with two Cs in their name has become president. ...Until Calvin Coolidge. 1928... No one who got ten million votes has lost. ...Until Al Smith. 1932... No Democrat has won since women secured the right to vote. ...Until FDR did. 1936... No president's been reelected with double-digit unemployment. ...Until FDR was. 1940... No one has won a third term. ...Until FDR did. 1944... No Democrat has won during wartime. ...Until FDR did. 1948... Democrats can't win without Alabama. ...Truman did. 1952... No Republican has won without winning the House or Senate. ...Eisenhower did. 1956... No one can beat the same nominee a second time in a leap year rematch. ...Until Eisenhower. 1960... Catholics can't win. ...Until Kennedy. 1964... Every Republican who's taken Louisiana has won. ...Until Goldwater. [The panel is zoomed in on Cueball's head in this frame.] 1968... No Republican vice president has risen to the Presidency through an election. ...Until Nixon. [The panel is zoomed in on Cueball's head in this frame.] 1972... Quakers can't win twice. ...Until Nixon did. 1976... No one who lost New Mexico has won. ...But Carter did. 1980... No one has been elected president after a divorce. ...Until Reagan was. 1984... No left-handed president has been reelected. ...Until Reagan was. [The panel is zoomed in on Cueball's head in this frame.] 1988... No one with two middle names has become president. ...Until "Herbert Walker". [The panel is zoomed in on Cueball's head in this frame.] 1992... No Democrat has won without a majority of the Catholic vote. ...Until Clinton did. [The precedent takes up the entire panel this year. Consequently, there is no Cueball.] 1996... No Dem. incumbent without combat experience has beaten someone whose first name is worth more in Scrabble. ...Until Bill beat Bob. 2000... No Republican has won without Vermont. ...Until Bush did. [The panel is zoomed in on Cueball's head in this frame.] 2004... No Republican without combat experience has beaten someone two inches taller ...Until Bush did. 2008... No Democrat can win without Missouri. ...Until Obama did. 2012... Democratic incumbents never beat taller challengers. ... Until Obama did. [The panel is zoomed in on Cueball's head in this frame.] 2016... No one has become president without government or military experience. ... Until Trump did. 2020? No one has won after being impeached. ✓ 2020? No challenger with a website has won. X [Caption below the comic] Congratulations to President-Elect Joe Biden for breaking the website curse!

This comic is an update to 1122: Electoral Precedent , adding "broken precedents" for the US presidential elections in 2016 and 2020. It was published six days after the 2020 election took place, and two days after most news networks "called" the election , projecting Biden as the winner. The majority of the comic's panels are duplicates from 1122, with the exception of the 2012 panel (modified to show that Obama did in fact break the streak), the 2016 panel (added to reflect the election of Donald Trump), and the two 2020 panels. It continues the theme of pointing out that an arbitrary 'precedent' can always be invoked to predict the outcome of an election. Presidential elections happen rarely enough that each is a unique event, and something is always happening for the first time. Like with the other examples, the precedents mentioned here mix factors that could plausibly impact the election (such as one candidate having been impeached), with precedents that are just a product of time and chance (like a successful challenger having a website). The final two panels again show how, no matter which candidate won in 2020, it would be a 'first' in some way. The 2020 election was also precedent-breaking in a few ways that Randall didn't mention: Also, Biden is the first president from the state of Delaware, thus he broke the "precedent" that Delawareans can't win. Randall then proceeds to combine these 2 facts to create a new precedent: Only Delawareans can defeat incumbents with a website. All original options can be found at 1122: Electoral Precedent . The problem with statements like "No <party> candidate has won the election without <state>" Or "No president has been reelected under <circumstances>" ★ Updated for 2020 ★ [Each statement below has its own panel. The year is in a caption, the precedent is stated by a standing Cueball in the main panel, and the president who broke it is below the panel.] 1788... No one has been elected president before. ...But Washington was. 1792... No incumbent has ever been reelected. ...Until Washington. 1796... No one without false teeth has become president. ...But Adams did. 1800... No challenger has beaten an incumbent. ...But Jefferson did. 1804... No incumbent has beaten a challenger. ...Until Jefferson. 1808... No congressman has ever become president. ...Until Madison. 1812... No one can win without New York. ...But Madison did. 1816... No candidate who doesn't wear a wig can get elected. ...Until Monroe was. 1820... No one who wears pants instead of breeches can be reelected. ...But Monroe was. 1824... No one has ever won without a popular majority. ...J.Q. Adams did. 1828... Only people from Massachusetts and Virginia can win. ...Until Jackson did. 1832... The only presidents who get reelected are Virginians. ...Until Jackson. 1836... New Yorkers always lose. ...Until Van Buren. 1840... No one over 65 has won the presidency. ...Until Harrison did. 1844... No one who's lost his home state has won. ...But Polk did. 1848... As goes Mississippi, so goes the nation. ...Until 1848. 1852... New England Democrats can't win. ...Until Pierce did. 1856... No one can become president without getting married. ...Until Buchanan did. 1860... No one over 6'3" can get elected. ...Until Lincoln. 1864... No one with a beard has been reelected. ...But Lincoln was. 1868... No one can be president if their parents are alive. ...Until Grant. 1872... No one with a beard has been reelected in peacetime. ...Until Grant was. 1876... No one can win a majority of the popular vote and still lose. ...Tilden did. 1880... As goes California, so goes the nation. ...Until it went Hancock. 1884... Candidates named "James" can't lose. ...Until James Blaine. 1888... No sitting president has been beaten since the Civil War. ...Cleveland was. 1892... No former president has been elected. ...Until Cleveland. 1896... Tall Midwesterners are unbeatable. ...Bryan wasn't. 1900... No Republican shorter than 5'8" has been reelected. ...Until McKinley was. 1904... No one under 45 has been elected. ...Roosevelt did. 1908... No Republican who hasn't served in the military has won. ...Until Taft. [The precedent takes up the entire panel this year. Consequently, there is no Cueball.] 1912... After Lincoln beat the Democrats while sporting a beard with no mustache, the only Democrats who can win have a mustache with no beard. ...Wilson had neither. 1916... No Democrat has won while losing West Virginia. ...Wilson did. 1920... No incumbent senator has won. ...Until Harding. 1924... No one with two Cs in their name has become president. ...Until Calvin Coolidge. 1928... No one who got ten million votes has lost. ...Until Al Smith. 1932... No Democrat has won since women secured the right to vote. ...Until FDR did. 1936... No president's been reelected with double-digit unemployment. ...Until FDR was. 1940... No one has won a third term. ...Until FDR did. 1944... No Democrat has won during wartime. ...Until FDR did. 1948... Democrats can't win without Alabama. ...Truman did. 1952... No Republican has won without winning the House or Senate. ...Eisenhower did. 1956... No one can beat the same nominee a second time in a leap year rematch. ...Until Eisenhower. 1960... Catholics can't win. ...Until Kennedy. 1964... Every Republican who's taken Louisiana has won. ...Until Goldwater. [The panel is zoomed in on Cueball's head in this frame.] 1968... No Republican vice president has risen to the Presidency through an election. ...Until Nixon. [The panel is zoomed in on Cueball's head in this frame.] 1972... Quakers can't win twice. ...Until Nixon did. 1976... No one who lost New Mexico has won. ...But Carter did. 1980... No one has been elected president after a divorce. ...Until Reagan was. 1984... No left-handed president has been reelected. ...Until Reagan was. [The panel is zoomed in on Cueball's head in this frame.] 1988... No one with two middle names has become president. ...Until "Herbert Walker". [The panel is zoomed in on Cueball's head in this frame.] 1992... No Democrat has won without a majority of the Catholic vote. ...Until Clinton did. [The precedent takes up the entire panel this year. Consequently, there is no Cueball.] 1996... No Dem. incumbent without combat experience has beaten someone whose first name is worth more in Scrabble. ...Until Bill beat Bob. 2000... No Republican has won without Vermont. ...Until Bush did. [The panel is zoomed in on Cueball's head in this frame.] 2004... No Republican without combat experience has beaten someone two inches taller ...Until Bush did. 2008... No Democrat can win without Missouri. ...Until Obama did. 2012... Democratic incumbents never beat taller challengers. ... Until Obama did. [The panel is zoomed in on Cueball's head in this frame.] 2016... No one has become president without government or military experience. ... Until Trump did. 2020? No one has won after being impeached. ✓ 2020? No challenger with a website has won. X [Caption below the comic] Congratulations to President-Elect Joe Biden for breaking the website curse!

Set in the Present

Set in the Present

https://www.xkcd.com/2384

https://www.explainxkcd.com/wiki/index.php/2384:_Set_in_the_Present

[Cueball is standing and watching a presumed typical wall mounted flat-screen television. There is no background, nor other physical features, just Cueball and the obliquely aligned screen positioned to also let us view its foreshortened image. In this, Megan and Ponytail are seen talking face to face with hands almost or actually in contact. Their faces are sociably close together and they are not shown as wearing masks. In the background of the scene are several other Cueball-like figures, not notably masked up or distanced from each other, and two may be holding hands. Cueball himself is given a large thought bubble above him, within which is written his current, distracted train of thoughts:] Cueball: Okay, they're hugging, and no one has masks, but she has a modern phone. Is this story set in 2019? Cueball: Or is this a post-vaccine future? Or an alternate no-COVID timeline? Cueball: Or are we supposed to think these characters are irresponsible? [Caption below the panel:] Movies and shows that are vaguely set in "the present" will be awkward for a while.

This comic is another in a series of comics related to the COVID-19 pandemic . Cueball is watching a wall-mounted television set that's showing either a movie or a TV program, and notices that none of the characters are taking the recommended precautions concerning the COVID-19 pandemic . This leads him to speculate on the timeline and internal logic of the show. On-screen, people are talking face-to-face without face masks, and other maskless people mingle in the background. Cueball notes that, if the story takes place in the same reality and time as us, the absence of precautions should mark the characters as reckless or irresponsible (which impacts the story). Alternative explanations he comes up with are that the show might be set either prior to the pandemic or far enough in the future that the impacts are no longer visible. However, these possibilities are be difficult to square with era-specific cues like technology and popular culture references. Billie Eilish is an American singer and songwriter who first became active in 2015, and rose to stardom in 2019, so a reference to her implies a show set within the last few years, and likely only one year in the past. The presence of "modern" phones (presumably a late model smartphone) has a similar implication. But in a TV show or film series where time passes in-universe, this also creates problems. If it's set in the recent past, and the series continues for a few more years, then the characters should encounter the pandemic in later seasons. If it's set in the future, then the entire series must be set in the future (because none of it included the pandemic). If the series has gone on for several years, the current episode must be at least several years in the future, which raises the question of why all the technology and pop culture shown is familiar to us. The simplest explanation is that COVID-19 doesn't exist within the program's universe (an idea Cueball briefly considers as an " alternate timeline ," but doesn't dwell on). Perfect consistency with the real world in fiction is hard to achieve, and how accurately stories track to current events varies widely. Movies and television productions are enormously complex, and months, if not years, can pass between when a screenplay is written and the finished product is released. This means that rapid changes in the real world are rarely reflected promptly in fiction. Alternately, the production might have taken place in the COVID era but the creators consciously chose not to include the pandemic in the story. Some viewers can ignore these inconsistencies, but for others, they make suspension of disbelief impossible. Cueball has previously been distracted by minor details in film or television in 1451: Background Screens . The idea of using thumbtacks and strings (usually accompanied by newspaper clippings and photographs) to study a problem is pop-culture shorthand for a conspiracy theory . Randall has previously mentioned this in 2244: Thumbtacks And String . [Cueball is standing and watching a presumed typical wall mounted flat-screen television. There is no background, nor other physical features, just Cueball and the obliquely aligned screen positioned to also let us view its foreshortened image. In this, Megan and Ponytail are seen talking face to face with hands almost or actually in contact. Their faces are sociably close together and they are not shown as wearing masks. In the background of the scene are several other Cueball-like figures, not notably masked up or distanced from each other, and two may be holding hands. Cueball himself is given a large thought bubble above him, within which is written his current, distracted train of thoughts:] Cueball: Okay, they're hugging, and no one has masks, but she has a modern phone. Is this story set in 2019? Cueball: Or is this a post-vaccine future? Or an alternate no-COVID timeline? Cueball: Or are we supposed to think these characters are irresponsible? [Caption below the panel:] Movies and shows that are vaguely set in "the present" will be awkward for a while.

Final Exam

Final Exam

https://www.xkcd.com/2385

https://www.explainxkcd.com/wiki/index.php/2385:_Final_Exam

[Ponytail is standing in front of a whiteboard addressing someone off-panel to the left.] Ponytail: Welcome to your final exam. Ponytail: The exam is now over. Ponytail: I'm afraid all of you failed. Ponytail: Your grades have been stored on our department server and will be submitted tomorrow. Ponytail: Class dismissed. [Caption below the panel:] Cybersecurity final exams

In this comic, Ponytail appears to be administering a group sitting for cybersecurity exam. However, at the beginning of the exam, she informs her students that they have all failed, despite not having taken a test yet. She then informs them that their grades are stored on the department server and will be submitted the next day. The implication here is that the true test, rather than being a traditional exam, is actually whether the students can hack into the server and change their grades. This may be a jab at education security which is known to be vulnerable to assault ( not the first time XKCD has made such a joke). In real life, students have attempted to change their grades in this manner, with occasional success. The title text adds a twist to this. In order for a student to get a good grade in the game theory class, they need to get a below-average grade on this final exam. This incentivizes the students to also change the grades of other students when they change their grade. However, this is more complicated than it seems, and depends on various factors, such as the fraction of students who take game theory in addition to cybersecurity. If, for example, half of the students also take game theory, then for all of them to get 80% of the average score, even assuming that all their non-game-theory classmates get maximum possible score, they would have to target for 2/3 (or about 67%) of the maximum possible score, to get 80% of the final average. While that would make their game theory grade perfect, it might noticeably worsen their cybersecurity grade. This gets progressively worse with the increasing fraction of students who take game theory along with cybersecurity. In the extreme case of all cybersecurity students also taking game theory class, this degenerates into another common game theory problem: Guess 2/3 of the average of everybody's guesses. The only winning strategy is, of course, for everyone to guess 0, which means that 2/3 of the average will be 0. This assumes perfect rationality of all players with respect to the game theory problem. The catch is that here we have the same number as a grade for the cybersecurity exam and for the game theory guess. We'd like one to be as high as possible, and the other to be zero or close to zero, which are obviously conflicting goals. To improve their overall results, students could resort to various compromises and strategies, such as increasing other students' scores against their will, or making alliances with students who might not mind taking a hit to their game theory grade (perhaps in exchange for other incentives) - these are all topics that the game theory class would have been dealing with. Specifically, this test seems to refer to the prisoner's dilemma and tragedy of the commons ; if one student changes their grade to 80% of the average, they will receive high marks, but if more and more students attempt this, the gain for each one drops and tends towards zero. The combination with cybersecurity adds another layer of complexity, in that students could, for example, also attempt to lock each other out of the server to achieve maximum control over the results to their benefit. In the strip, there is no actual test to take. But if there was one, there would still be strategies to optimize performance without hacking the grades. One option would be to take the test normally, and then change every fifth answer to the bubble below it; using this strategy your overall grade will drop to 80% if you were at 100%, and may even raise your score if a student performed particularly poorly. The trick, though, is that other students (assuming rationality) would try this strategy as well; thus, a student may need to overcorrect more, weigh the possibilities of whether any of their classmates had followed this as well, and perform this recursively until it is most likely that the score is 80 percent of the average. Note: All of the above is based on the assumption that the game theory mark will be directly (and not inversely) proportional to how close the cybersecurity grade is to 80% of the average. This is left ambiguous in the formulation. Note: The above also assumes the system accepts a maximum of 100%. If (as is likely) the system allows for extra credit you could reach a Nash equilibrium by setting the non-game theory students to an arbitrary, but very high, number (say 2000%) C and then the game theory students to (C*g)/(.25+g) where g is the percentage of students not in game theory. Note: The solution becomes trivial if the game-theory grade is stored on the same server but submitted after the cybersecurity grade. Students would simply give themselves full marks on cybersecurity, then edit the game-theory grade after cybersecurity has been submitted. [Ponytail is standing in front of a whiteboard addressing someone off-panel to the left.] Ponytail: Welcome to your final exam. Ponytail: The exam is now over. Ponytail: I'm afraid all of you failed. Ponytail: Your grades have been stored on our department server and will be submitted tomorrow. Ponytail: Class dismissed. [Caption below the panel:] Cybersecurity final exams

Ten Years

Ten Years

https://www.xkcd.com/2386

https://www.explainxkcd.com/wiki/index.php/2386:_Ten_Years

From 1141: Two Years [Randall (drawn as Cueball) and Randall's fiancée (drawn as Megan) sit on a bed, Randall's fiancée is talking on the phone. The person she is talking to, a doctor holding a clipboard, is shown inset.] Randall's fiancée: Oh god. [Randall and Randall's fiancée sit together while Randall's fiancée, now bald, is receiving chemotherapy. They are both on their laptops.] IV pump: ... Beeep ... Beeep ... Beeep ... [Randall and Randall's fiancée (who is wearing a knit cap) are paddling a kayak against a scenic mountain backdrop.] [Randall and Randall's fiancée sit at a table, staring at a cell phone. There is a clock on the wall. Her head is stubbly.] Randall's fiancée: How long can it take to read a scan!? [Randall and Randall's fiancée are back at the hospital again, Randall's fiancée receiving chemo. They are playing Scrabble.] Randall: "Zarg" isn't a word. Randall's fiancée: But caaaancer. Randall: ...Ok, fine. [Randall and Randall's fiancée (wearing a knit cap) are listening to a Cueball-like friend. A large thought bubble is above their heads and it obscures the friends talk. The text below, split in three is the only part there can be no doubt about:] Friend: So next year you should come visit us up in the mounta a and Randall and Randall's fiancée (thinking): "Next year" [Randall and Randall's fiancée are getting married, with a heart above their heads. Randall's wife's hair is growing back.] [Randall and Randall's wife (wearing a knit cap) stand on a beach, watching a whale jump out of water.] Fwoosh From 1928: Seven Years [Randall and Randall's wife (with her hair noticeably longer) are walking through a forest.] [Randall's wife is sitting down, not in the forest anymore.] Randall's wife: My toe hurts and I found a report of a case in which toe pain was an early sign of cancer spreading. Randall: Wait—didn’t you stub your toe yesterday? Randall's wife: Yes, but what if this is unrelated? [Randall and his wife are going spelunking. The guide is gesturing deeper into the cave while Randall and his wife are climbing down.] [Randall's wife stands on a rock above an alligator in a swamp, photographing the alligator. Randall is on a balcony behind safety railings.] Randall: When they estimated your survival odds, I think they made some optimistic assumptions about your hobbies. [Randall's wife sits on an examination bed, listening to a doctor holding a clipboard.] Doctor: This is probably nothing. Doctor: But given your history, we should do a full scan. Doctor: We'll call with the results in a few days. Try not to worry about it until then! [Randall and his wife stand above a deep pond full of fish and other objects. Randall's wife is piloting a wired underwater camera with lights.] [Randall and his wife are standing next to each other. Randall's wife has shoulder-length hair covering most of her face.] Randall's wife: Hard to believe—six years ago, I was bald. But today, after a long struggle, I finally look like the little girl from The Ring . Randall: That's, uhh... good? Randall's wife: Hissssss [A line of six people, including Randall and his wife, stand and watch the solar eclipse.] New to 2386: Ten Years : [Randall and his wife are sitting in a room with five bunnies sitting around and on them. The Poster on the wall reads: Rabbit rescue.] Randall: Do you think they're socialized enough? Randall's wife: This one might need one more head pat. [Randall is running and pushing his wife on a hand cart.] Someone off-panel: Has anyone seen the hand cart? Randall's wife: Wheee! [Randall and his wife walks up hill with snowy mountains near by and in the background. his wife is gesturing to something ahead of them.] [A large dark panel, to the right of the previous three, to the left in two rows. Randall and his wife sits, leaning back on their hands looking up, at the end of a pier going into a lake. The end is broader and they sit to each side of the middle of he pier. It is night and behind the lake there is a forest of pine trees. Above the three is a clear starlit night sky with hundreds of stars and the band of the Milky Way clearly visible. The trees and some of the stars are reflected in the water of the lake, distorted by the movements of the water.] [Randall is sitting on a grassy field, a bit higher than his wife who lies on her back looking up.] Randall: You did it. Randall: Ten years. Randall's wife: It doesn't seem real. [Zoom in on Randall's wife, who is not longer lying down.] Randall's wife: When they showed me my 10-year survival chart, I really didn't believe I would make it here. Randall's wife: I don't understand why you married me when it looked so bad. Randall's wife: But it was very sweet. [In a frame-less panel Randall is standing in front of his wife, who is sitting on the ground, arm leaning on her bent knees.] Randall: You make it sound like an act of grace, and not something I desperately wanted to do and was worried I wouldn't get to. Randall: You're the coolest person I've ever met. I just wanted whatever time we could have. [Same setting but seen from a distance and in silhouette. Randall's wife has lifted her fist towards the sky, and it seems like Randall has turned away from her looking up.] Randall's wife: Well, good news, my hideous and inexplicable existence continues unabated! Take that, Biology! Randall's wife: You failed to kill me and now I can never die! Randall: Is... that how it works? Randall's wife: It was in the fine print on the chart.

Randall 's then-fiancée, now wife was diagnosed with cancer in late 2010. This is a matter he has discussed in the comic multiple times before , with Randall being depicted as Cueball and his wife as Megan. It has been 10 years since her diagnosis and treatments. This comic is a continuation of 1141: Two Years and 1928: Seven Years , which are shown in the first 16 panels, slightly grayed out. The first of the new panels shows Randall and his wife at a "Rabbit Rescue", interacting with buns ( a recurring theme of xkcd). The purpose of such events is to get rescued (often surrendered or seized) rabbits or other animals used to interacting with each other and with unfamiliar humans under controlled circumstances, to help them be more suitable as pets and hopefully entice visitors to adopt them. Randall facetiously asks his wife if she thinks the rabbits have socialized enough, even though he and his wife are there for the sake of their own enjoyment (and she indicates that she would like to spend more time patting a bunny on its head). In the next panel, Randall is pushing his wife in a handcart, which is presumably stolen. (As evidenced by the off-panel person asking if anybody has seen the handcart.) The third new panel shows Randall and his wife exploring a mountain. They appear to have found something interesting, due to Megan pointing her finger towards something off-panel. It appears to be a reference to a similar climbing scene from 1190: Time . The fourth panel shows Randall and his wife sitting on the edge of a pier, looking at the night sky. This is a typical romantic nighttime activity. The panel is distinguished because there was considerably more effort put into the drawing of this panel than of the other panels, by virtue of it being nighttime. Thus, the reflection of the starlight on their faces is the center of attention in the drawing. The final new panels show Randall and his wife sitting on a hill, talking about how they couldn't believe that Megan would make it to 10 years cancer-free, which according to 881: Probability wasn't all that certain (77% probability -- the probability of picking an M&M out of a bag at random and getting one that isn't blue ). Randall's wife voices a concern that she had seemingly been carrying for a while, that she was a burden to Randall, and explains that she couldn't understand why he would marry her, except as a show of grace. Randall firmly rejects this notion, stating that it was no mere gesture, but that it was important to him that they enjoy "whatever time we could have". Finally, and as with the first comic in the series, the comic takes a light-hearted turn: because the table does not include values for probability of survival more than ten years after treatment, Randall's wife jokingly concludes that she is now immortal, perhaps thanks to a cursed artifact. Many anniversaries are traditionally marked by giving gifts, such as the silver jubilee after twenty-five years of marriage (or of a monarch's reign, or an employee's seniority within a company, or anything else). The tenth anniversary is traditionally associated with a tin gift (tin being a much more precious metal in 1922 than it is today), but maybe Randall bought it at a cursed shop . The title-text expands on this final joke, as it suggests that there is an official name for this giving of cursed artifacts once the ten-year mark has passed. Also, it seems as though Randall has finally found a less-gross name for this anniversary than "biopsy-versary". Cursed artifacts that cannot die were recently mentioned in 2332: Cursed Chair . From 1141: Two Years [Randall (drawn as Cueball) and Randall's fiancée (drawn as Megan) sit on a bed, Randall's fiancée is talking on the phone. The person she is talking to, a doctor holding a clipboard, is shown inset.] Randall's fiancée: Oh god. [Randall and Randall's fiancée sit together while Randall's fiancée, now bald, is receiving chemotherapy. They are both on their laptops.] IV pump: ... Beeep ... Beeep ... Beeep ... [Randall and Randall's fiancée (who is wearing a knit cap) are paddling a kayak against a scenic mountain backdrop.] [Randall and Randall's fiancée sit at a table, staring at a cell phone. There is a clock on the wall. Her head is stubbly.] Randall's fiancée: How long can it take to read a scan!? [Randall and Randall's fiancée are back at the hospital again, Randall's fiancée receiving chemo. They are playing Scrabble.] Randall: "Zarg" isn't a word. Randall's fiancée: But caaaancer. Randall: ...Ok, fine. [Randall and Randall's fiancée (wearing a knit cap) are listening to a Cueball-like friend. A large thought bubble is above their heads and it obscures the friends talk. The text below, split in three is the only part there can be no doubt about:] Friend: So next year you should come visit us up in the mounta a and Randall and Randall's fiancée (thinking): "Next year" [Randall and Randall's fiancée are getting married, with a heart above their heads. Randall's wife's hair is growing back.] [Randall and Randall's wife (wearing a knit cap) stand on a beach, watching a whale jump out of water.] Fwoosh From 1928: Seven Years [Randall and Randall's wife (with her hair noticeably longer) are walking through a forest.] [Randall's wife is sitting down, not in the forest anymore.] Randall's wife: My toe hurts and I found a report of a case in which toe pain was an early sign of cancer spreading. Randall: Wait—didn’t you stub your toe yesterday? Randall's wife: Yes, but what if this is unrelated? [Randall and his wife are going spelunking. The guide is gesturing deeper into the cave while Randall and his wife are climbing down.] [Randall's wife stands on a rock above an alligator in a swamp, photographing the alligator. Randall is on a balcony behind safety railings.] Randall: When they estimated your survival odds, I think they made some optimistic assumptions about your hobbies. [Randall's wife sits on an examination bed, listening to a doctor holding a clipboard.] Doctor: This is probably nothing. Doctor: But given your history, we should do a full scan. Doctor: We'll call with the results in a few days. Try not to worry about it until then! [Randall and his wife stand above a deep pond full of fish and other objects. Randall's wife is piloting a wired underwater camera with lights.] [Randall and his wife are standing next to each other. Randall's wife has shoulder-length hair covering most of her face.] Randall's wife: Hard to believe—six years ago, I was bald. But today, after a long struggle, I finally look like the little girl from The Ring . Randall: That's, uhh... good? Randall's wife: Hissssss [A line of six people, including Randall and his wife, stand and watch the solar eclipse.] New to 2386: Ten Years : [Randall and his wife are sitting in a room with five bunnies sitting around and on them. The Poster on the wall reads: Rabbit rescue.] Randall: Do you think they're socialized enough? Randall's wife: This one might need one more head pat. [Randall is running and pushing his wife on a hand cart.] Someone off-panel: Has anyone seen the hand cart? Randall's wife: Wheee! [Randall and his wife walks up hill with snowy mountains near by and in the background. his wife is gesturing to something ahead of them.] [A large dark panel, to the right of the previous three, to the left in two rows. Randall and his wife sits, leaning back on their hands looking up, at the end of a pier going into a lake. The end is broader and they sit to each side of the middle of he pier. It is night and behind the lake there is a forest of pine trees. Above the three is a clear starlit night sky with hundreds of stars and the band of the Milky Way clearly visible. The trees and some of the stars are reflected in the water of the lake, distorted by the movements of the water.] [Randall is sitting on a grassy field, a bit higher than his wife who lies on her back looking up.] Randall: You did it. Randall: Ten years. Randall's wife: It doesn't seem real. [Zoom in on Randall's wife, who is not longer lying down.] Randall's wife: When they showed me my 10-year survival chart, I really didn't believe I would make it here. Randall's wife: I don't understand why you married me when it looked so bad. Randall's wife: But it was very sweet. [In a frame-less panel Randall is standing in front of his wife, who is sitting on the ground, arm leaning on her bent knees.] Randall: You make it sound like an act of grace, and not something I desperately wanted to do and was worried I wouldn't get to. Randall: You're the coolest person I've ever met. I just wanted whatever time we could have. [Same setting but seen from a distance and in silhouette. Randall's wife has lifted her fist towards the sky, and it seems like Randall has turned away from her looking up.] Randall's wife: Well, good news, my hideous and inexplicable existence continues unabated! Take that, Biology! Randall's wife: You failed to kill me and now I can never die! Randall: Is... that how it works? Randall's wife: It was in the fine print on the chart.

Blair Witch

Blair Witch

https://www.xkcd.com/2387

https://www.explainxkcd.com/wiki/index.php/2387:_Blair_Witch

[Megan is standing in front of a screen looking away from it at an audience off-panel. She is holding a stick, pointed at the chart behind her. The chart shows the stick figure from The Blair Witch Project . Above is an unreadable line of text, and below are two smaller rectangles a smaller one above the other, the small seems to be empty, but there seems to be some kind of graph in the bottom one.] Megan: Other than the fake 1999 video, there have been no Blair Witch sightings in 30+ years. Megan: The IUCN redlist says the witch is "possibly extinct in the wild." [A close-up of Megan's face. The screen now shows a habitat map, with four separate shaded areas enclosed in a dotted line. The dotted line and one of the areas goes to the upper edge of the screen indicating they continue beyond the shown area. Beneath the dotted line and to the right there are three small squares, one of them clearly shaded the same way as the areas above. Next to each there is an unreadable label.] Megan: Development in the Maryland suburbs has fragmented the spooky forest habitat. Megan: Climate change will push any remnant populations north. [Back to the original setting, Megan is standing with the stick pointing downwards, and the chart is out of frame.] Megan: That's why we plan to capture any surviving witches and establish a breeding population. Megan: Then, in time, the Blair Witch Reintroduction Project can begin.

The Blair Witch Project is a found footage horror film released in 1999. For the marketing campaign of the film, the producers created the legend of the Blair Witch, a supernatural being whose legend originates in Burkittsville , MD. As it sometimes happened in Protestant societies in the colonial era , a woman was ostracized from the community after having been accused of witchcraft . This woman, who tends to conflict in name with various versions of the lore, would supposedly attempt to inflict revenge upon the community that exiled her, and these fearful people fled from the town. The comic takes a humorous turn on the legend, suggesting a conservation program to save the Blair Witch. While the film was described by reliable sources as faked and misrepresented footage, the Blair Witch is postulated as separate species that is being tracked by the IUCN Red List . With the rise of camera-phones in the modern age, sightings of beings that are most likely fictitious , such as Bigfoot and the Loch Ness Monster, are becoming rarer over time, due to lack of credibility of a reported sighting without visual evidence (although with the rise of deepfakes, even visual evidence might lose credibility in the future). A species which has not been notably documented for a long time would indeed be moved to the "possibly extinct in the wild " category, as Megan notes. Rather than taking this to mean the Blair Witch does not exist however, Megan instead suggests habitat loss as the reason why encountering a Blair Witch might be more difficult. Habitat loss is in fact one of the most prominent and concerning reasons for extinction in recent years. Megan claims that suburban projects have fragmented the witch's "spooky forest" ecosystem, a reference to the many species that are dying off due to encroachment, logging, and similar human activities. Migration due to climate change is also an observable phenomenon in animal populations (and some plant populations, depending on their mode of travel while in seeds; those that rely on animals to germinate will migrate as well). Megan then proposes a plan to catch and breed Blair Witches in an attempt to resurrect the species. This final panel is more obviously humorous, as even if the Blair Witch did exist separate from humans, there is only one, [ citation needed ] and thus any attempt to breed and repopulate would be futile. It may be possible that this is not a problem , but if it is, it could also raise the objection that any pair of Blair Witch may both be female, and thus unable to reproduce. This could be resolved by (a) assuming that Witches can ( sometimes? ) be male as well, or (b) assuming that, much like Tremblay's salamander, females can reproduce with a male of a related species (most likely human, in which case the project might have difficulty obtaining approval from an ethics review board .) The phrase "Blair Witch Reintroduction Project" is a reference to The Blair Witch Project . The title-text suggests that the comic is a lecture, as Megan's whiteboard and pointer would suggest. A (presumed) student asks whether Megan is concerned that witches won't breed in captivity (a serious real-world concern to the IUCN). If this is a press conference, the question would be asked by a reporter instead. Megan replies that they are worried that there will be breeding, but biologists are unsure how the breeding occurs, calling it "harrowing" (presumably because they have captured the Blair Witch and it has set a curse on their laboratory as she supposedly did in Burkittsville). Historically, communities practicing witchcraft may have fled to the woods to engage in sometimes very sexual behaviors that others at the time were very frightened by. Randall previously wrote about an ill-advised fauna introduction project in 2349: Rabbit Introduction , but at least rabbits are cuter and less harrowing than witches. [ citation needed ] [Megan is standing in front of a screen looking away from it at an audience off-panel. She is holding a stick, pointed at the chart behind her. The chart shows the stick figure from The Blair Witch Project . Above is an unreadable line of text, and below are two smaller rectangles a smaller one above the other, the small seems to be empty, but there seems to be some kind of graph in the bottom one.] Megan: Other than the fake 1999 video, there have been no Blair Witch sightings in 30+ years. Megan: The IUCN redlist says the witch is "possibly extinct in the wild." [A close-up of Megan's face. The screen now shows a habitat map, with four separate shaded areas enclosed in a dotted line. The dotted line and one of the areas goes to the upper edge of the screen indicating they continue beyond the shown area. Beneath the dotted line and to the right there are three small squares, one of them clearly shaded the same way as the areas above. Next to each there is an unreadable label.] Megan: Development in the Maryland suburbs has fragmented the spooky forest habitat. Megan: Climate change will push any remnant populations north. [Back to the original setting, Megan is standing with the stick pointing downwards, and the chart is out of frame.] Megan: That's why we plan to capture any surviving witches and establish a breeding population. Megan: Then, in time, the Blair Witch Reintroduction Project can begin.

Viral Quiz Identity Theft

Viral Quiz Identity Theft

https://www.xkcd.com/2388

https://www.explainxkcd.com/wiki/index.php/2388:_Viral_Quiz_Identity_Theft

[Hairy and White Hat are standing across from each other at a table. Each has a laptop open in front of him.] Hairy: Here's my plan: we start a viral quiz to trick people into posting the name of the street they lived on as a kid. Hairy: Then we use it to steal their identity! White Hat: Okay. White Hat: Just checking, you know voter files and mortgages and stuff are mostly public records, right? Hairy: Huh? What are you talking about? White Hat: ...Nothing. We can do your thing.

Hairy is trying to compile a list of names and addresses, for identity theft purposes. He intends to do so by posting an online quiz to entice people into posting their personal information; for example, asking people to post their 'porn star name' by combining their pet's name (or their middle name, or their mother's maiden name) and the street they grew up on. However, as White Hat points out, a lot of this information is already in the public record making his "viral quiz" unnecessary. This comic is one of very few where White Hat's argument is not used as a straw man ; rather, Hairy is the unenlightened one and White Hat has the idea that will require much less work for the same result. However, when Hairy proves to have no idea about public records, White Hat decides that it will be easier (or at least more fun) to just play along with Hairy's plan rather than try to educate him. Even though White Hat is correct that there are public databases with lists of legal names and addresses, lots of online interactions take place in forums where people adopt pseudonyms. A viral quiz like this one could be useful for de-anonymizing users, a process known colloquially as " doxing ". There is also a suspicion that these kind of viral quizzes are used to create databases to answer password recovery questions correctly. Together with a man-in-the-middle attack on the email system used, this can lead to hackers taking over user accounts. In the title text, it turns out that lots of users did not provide their personal information. Instead they provided fake information, which Hairy naively takes as truth. The number '420' is associated with the use of marijuana and the number '69' is used to refer to a sex position . These two numbers have found their way into society from memes to car prices . White Hat could also be taking the data at its word when he replies that there must be a high-rise building at that address to hold so many respondents, but it is more likely that he is making a sarcastic double-entendre pun. 420 69th St. is a real address in several US cities, but it looks like they're all single-family dwellings or small offices, not high-rises. If Hairy had talked to Black Hat , he might have been told about the time Black Hat made a bunch of free web services to harvest usernames and passwords. Black Hat's project stalled when he realized that he didn't know what he wanted to do with the information he harvested, and Hairy's plan doesn't seem very well-thought-out past the "get personal details" step either. [Hairy and White Hat are standing across from each other at a table. Each has a laptop open in front of him.] Hairy: Here's my plan: we start a viral quiz to trick people into posting the name of the street they lived on as a kid. Hairy: Then we use it to steal their identity! White Hat: Okay. White Hat: Just checking, you know voter files and mortgages and stuff are mostly public records, right? Hairy: Huh? What are you talking about? White Hat: ...Nothing. We can do your thing.

Unread

Unread

https://www.xkcd.com/2389

https://www.explainxkcd.com/wiki/index.php/2389:_Unread

[A graph with the x-axis and y-axis labeled] [The graph has a line that starts near the bottom of the x-axis, fluctuates a little, then steadily increases until it is approaching the maximum of the y-axis, whereby it begins to level out] Percentage of received messages in the service that are marked unread Time ---> [Three Cueballs standing at different points on the graph. The first two are shown directly above the line at the beginning and middle areas, and the third is shown below it near the end of the graph. All three are holding phones.] [The first Cueball looks at his phone, which displays two notifications on an app] Oh hey, two new messages! [The next Cueball again looks at his phone, this time with 45 notifications on the app] Ugh, gotta take some time to go through these. [The last Cueball's phone app shows 10129 notifications] Wow, it hit five digits. [Caption below the panel] Another way every system eventually becomes email

Cueball has an unspecified communication application on his phone. As the chart displays, the longer he has the app, the more unread messages he has on it (likely due to a combination of more people trying to contact him over it and him checking it less diligently). Eventually, he gives up reading every message, and he notices apathetically when it reaches 10,000 notifications. The joke comes in the caption, which states that all communication services have this problem and implies that this problem is the key problem with email . The caption, " Another way every system eventually becomes email" (emphasis added) is a reference to Zawinski's law of software envelopment : "Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can." In this case, it's not that every program will eventually become capable of sending and receiving emails, but rather that Cueball/Randall will treat every program that provides notifications the same way he treats his email inbox. In the title text, Randall uses this reasoning to explain why he'll never install a smart smoke detector . A smart detector would send a notification to his phone when the smoke level is high enough to trigger it, or perhaps when it is running low on battery; following the same trend, Randall believes he will eventually stop reading the alerts from the smoke detector. Ignoring a smoke detector is dangerous. [ citation needed ] Traditional (non-smart) smoke detectors typically use sound to denote status, with very loud piercing sounds used to indicate events requiring immediate notice (i.e. an active fire producing large amounts of smoke) and quieter chirps to indicate other conditions, such as low battery levels. While some people can and do tune out the low battery warnings, it tends to be difficult to ignore the active fire types of alerts. However, a person would need to be within hearing range for those alerts, versus allowing people to ignore alerts from around the world with a smart smoke detector. Randall has previously covered his trouble keeping up with email, for example in 1783: Emails . [A graph with the x-axis and y-axis labeled] [The graph has a line that starts near the bottom of the x-axis, fluctuates a little, then steadily increases until it is approaching the maximum of the y-axis, whereby it begins to level out] Percentage of received messages in the service that are marked unread Time ---> [Three Cueballs standing at different points on the graph. The first two are shown directly above the line at the beginning and middle areas, and the third is shown below it near the end of the graph. All three are holding phones.] [The first Cueball looks at his phone, which displays two notifications on an app] Oh hey, two new messages! [The next Cueball again looks at his phone, this time with 45 notifications on the app] Ugh, gotta take some time to go through these. [The last Cueball's phone app shows 10129 notifications] Wow, it hit five digits. [Caption below the panel] Another way every system eventually becomes email

Linguists

Linguists

https://www.xkcd.com/2390

https://www.explainxkcd.com/wiki/index.php/2390:_Linguists

[Ponytail is walking to the left. A voice calls out from behind her (at the right of the panel):] Off-panel voice: Help! Off-panel voice: I fell down a hole! [Ponytail runs to the right, toward the hole.] [Ponytail, kneeling down next to the hole, calls out:] Ponytail: Hey! Ponytail: Is "fell down a hole" exactly equivalent to "fell in a hole," in your usage? Or do they have slightly different implications? [Caption below the panel] There's a myth that linguists are pedants who love correcting people, but they're actually just enthusiastic about understanding language in all its infinite varieties, which is much worse.

Ponytail hears the cries of an unidentified person who has become trapped in a hole. She rushes over, but rather than helping the person out, she instead asks whether the trapped person's chosen phrasing for their predicament – "fell down a hole" – is equivalent to "fell in a hole." To most people, the phrases "fell down a hole" and "fell in a hole" are paraphrases. To other people, however, the two sentences have a subtle difference that implies slightly different things; for example, whether one has fully or only partially fallen down/in the hole, how big the hole is, or whether the person has exited out of the hole yet at the time of speaking (see the paragraph on the title text below). Ponytail is thus asking whether the person chose to use 'down' over 'in' for those reasons. In either case, the joke here is that this is probably not the best time for Ponytail to ask. In the caption, Randall comments on the stereotype that linguists are obnoxious elitists who only love telling people how wrong they are (" Grammar Nazis "). A linguist might make a statement like this that ends with something like "linguists actually are only trying to describe existing grammar rules, not prescribe them." Instead, Randall takes the comment in an unexpected direction by saying not that linguists are better than expected but actually worse. He claims that seeking to extract exact information is worse than if they were pedants browbeating their audience, possibly because a pedant could prioritize the elements of a situation better than Ponytail is doing here. This is similar to the viewpoint dedicated to scientists in comic 877: Beauty , as in studying that field seems to be a cold and sad way to analyze the thing, but instead is an extreme form of child-like awe and inspiration. The title text sees Ponytail asking the person whether their answer is dependent on the current situation, or in technical terms, tense-aspect-mood . As noted above some people see the difference between 'fell down' and 'fell in' as to whether the sentence still holds true at the time of speaking; this is called the perfective aspect . There are other variations, such as recent vs. remote past: "I just fell down a hole"; the perfect (not to be confused with the first one - note the lack of -ive ): "I fell down a hole, and it has consequences relevant to our conversation"; habitual : "I had previously fallen down a(nother?) hole, and I have fallen down this hole now", all of which can influence one to choose 'down' over 'in' or vice versa. The last sentence “assuming you get out” drives home the point that Ponytail is concerning herself with linguistic matters over practical ones. Ponytail’s use of “assuming” rather than “when” suggests that Ponytail doesn’t have a plan to get the person out, or that she has a plan but isn’t confident in its success. The former interpretation, that Ponytail is thinking of the person getting out as abstract and unconnected with her, is funnier and more consistent with Ponytail’s actions so far. [Ponytail is walking to the left. A voice calls out from behind her (at the right of the panel):] Off-panel voice: Help! Off-panel voice: I fell down a hole! [Ponytail runs to the right, toward the hole.] [Ponytail, kneeling down next to the hole, calls out:] Ponytail: Hey! Ponytail: Is "fell down a hole" exactly equivalent to "fell in a hole," in your usage? Or do they have slightly different implications? [Caption below the panel] There's a myth that linguists are pedants who love correcting people, but they're actually just enthusiastic about understanding language in all its infinite varieties, which is much worse.

Life Before the Pandemic

Life Before the Pandemic

https://www.xkcd.com/2391

https://www.explainxkcd.com/wiki/index.php/2391:_Life_Before_the_Pandemic

[Megan and Cueball are having a conversation.] Megan: What do you miss most about life before the pandemic? Cueball: I can barely remember it. Megan: I miss going scuba diving without having to wear a mask. Cueball: I miss free refills at gas stations. Megan: I miss grilling in the library. [Close-up on Megan, Cueball's voice comes from off-panel, to the right.] Megan: I miss when tennis players didn't have to have that safety net between them. Cueball: I miss indoor fireworks. [The frame returns to seeing them both, they are now walking to the right while talking.] Megan: I miss when arcades let you take toys from the bin with your hand instead of using that stupid claw. Cueball: Ugh, I hate that thing. Megan: I can't wait for a vaccine.

This comic is another in a series of comics related to the COVID-19 pandemic . Megan and Cueball are having a conversation about life before the pandemic, which was declared as such on the 11th of March, 2020 by the World Health Organization. They talk about what they miss about life before the pandemic, but Cueball says that he can barely remember it. This is borne out by the rest of their discussion: None of the activities they list were ever common and most are strange, some are even forbidden and various items are misconstrued as existing for pandemic mitigation purposes. After they finish reminiscing, Megan says that she can't wait for a vaccine, further implying that she can't wait to have all of these things "back." Both Pfizer/BioNTech and Moderna are making vaccines, with Pfizer/BioNTech making their application for emergency use on November 20th, 2020, 7 days before this comic's release. It is expected to be approved for use by the end of the year. Scuba stands for Self-Contained Underwater Breathing Apparatus. It consists of a tank of compressed air, which is conducted through a tube to a mouthpiece which allows the diver to breathe underwater. A mask is a fundamental part of scuba diving to allow the diver to see underwater better. Cloth masks, to help lower the spread of the virus between people, are a recommended precaution when in public, but wearers are advised not to wear them when swimming. Megan is conflating these two different types of masks, misremembering a world where scuba diving did not have masks involved. You do not need to wear a cloth mask if you are scuba diving, but you do need to wear a scuba mask–irrespective of whether there is a pandemic. Scuba masks previously rated quite well on the mask effectiveness scale in 2367: Masks . However because the regulator is technically not a face covering, Megan's Scuba club may be requiring full face or "hardhat" style diving equipment, which would justify her complaint. Gas stations are locations where you can buy gasoline, which powers internal combustion engines, especially those in cars. Many of these locations have a small convenience store attached, where customers can purchase snacks or drinks while having their car filled up. It's unknown whether Randall/Ponytail meant "free refill" of gasoline or of drinks from the convenience store, but either way it was not a business practice that was common. [ citation needed ] Free refills of drinks are more associated with restaurants and diners, who allow free top-ups of relatively cheaper soft drinks, tea, or coffee, in the hopes that it will attract people to come in and buy more expensive meals to cover the cost. Grilling food generally poses a significant fire hazard (and can produce toxic carbon monoxide) and is thus typically not allowed indoors, especially in libraries, whose shelves full of flammable paper books present both an increased fire hazard (as the fire could spread more quickly with plenty of fuel, and the shelves could potentially hamper efforts to evacuate the library if the fire made that necessary) and a liability (because if the books burned, they would be destroyed/unusable, and it would likely cost a lot of money to replace them). In the pandemic, many libraries discourage people from spending time there, preferring that visitors only check out or drop off books. Some libraries have even removed chairs to achieve this. Even if grilling were allowed in Cueball's and Megan's library beforehand, it would not be allowed during the pandemic, as it would involve eating in an enclosed area, an activity specifically warned to increase the contagiousness of the virus. Backyard (or library) cookouts have been discouraged by the Center for Disease Control and Prevention , or CDC, because of this. Tennis is a sport where two players use racquets to hit a ball at each other. The game is played on a court divided in half by a low net. The net is not used for anyone's safety; it's to ensure that the ball must be volleyed to the other player with some minimum height. Megan seems to believe that the net is there to ensure that the players stay on opposite sides of the net, in order to lower the spread of the virus. Many indoor activities were moved outdoors during the COVID-19 pandemic, as poorly-ventilated indoor spaces vastly increase the chance of the virus spreading. Fireworks are explosives shot into the air for entertainment. Due to inherently being explosive, fireworks can be dangerous, i.e. cause injuries or even death. Some countries (for instance, The Netherlands) have temporarily banned fireworks because of COVID-19, reasoning the fireworks-induced injuries would put additional stress on hospitals that are already nearing maximum (intensive care) capacity due to COVID cases. Most fireworks are not suitable for use indoors; setting them off indoors is even more dangerous than they already are, even before the pandemic. [ citation needed ] However, there are specially designed indoor fireworks, most often used by specially trained and licensed pyrotechnicians. These are usually seen in large indoor venues for concerts and sporting events, both of which have been curtailed due to the pandemic. In this case Cueball would be accurately lamenting his inability to enjoy indoor fireworks. Arcade claw machines have a bin of prizes (often stuffed animals) with a claw mechanism hanging overhead. The player pays a few coins into the machine and maneuvers the claw over a desired prize. The claw will descend and "attempt" to grab the prize for retrieval. There is often a hidden percentage chance that the claw will not fully close. This is a frustrating experience for the player (e.g. Cueball), but he misunderstands the purpose of the claws. While manipulator arms are also used for handling dangerous items, the claws in these machines are not to reduce coronavirus spread. Instead, they make toy-grabbing deliberately inefficient so that people may play again and pay more money. If people could take toys freely from the bin with their hands, operators would lose money, as people could take multiple toys or avoid paying entirely. It is unlikely that they would allow this even after the pandemic. Out of frustration, some players attempt to reach through the deposit hole in order to try to take one of the stuffed animals or other prizes without the use of the claw. Since multiple people would presumably have already touched the metal interior, this is an effective way to spread the contagion quickly, which makes it even more imperative to discontinue this practice. There are other dangers to doing this as well; one can get their arm stuck in the machine , and can even cause themselves serious damage. Again it is possible that the arcade used a ticket or token system where one could cash out their winnings for self-selected items such as plush toys. As a COVID mitigation, the arcade may have found it necessary to make the plush toys only available via an enclosed claw style "skill" game. A mall, in a historical context, refers to a large open walkway, such as the National Mall , where one could conceivably enter with a horse, although it was considered inappropriate to do so. However, it appears Cueball and Megan are referring to a shopping mall , where a shopper entering with a horse was never a regular occurrence [ citation needed ] , at least in universes where there isn’t a horse in aisle five . [Megan and Cueball are having a conversation.] Megan: What do you miss most about life before the pandemic? Cueball: I can barely remember it. Megan: I miss going scuba diving without having to wear a mask. Cueball: I miss free refills at gas stations. Megan: I miss grilling in the library. [Close-up on Megan, Cueball's voice comes from off-panel, to the right.] Megan: I miss when tennis players didn't have to have that safety net between them. Cueball: I miss indoor fireworks. [The frame returns to seeing them both, they are now walking to the right while talking.] Megan: I miss when arcades let you take toys from the bin with your hand instead of using that stupid claw. Cueball: Ugh, I hate that thing. Megan: I can't wait for a vaccine.

Cyber Cafe

Cyber Cafe

https://www.xkcd.com/2392

https://www.explainxkcd.com/wiki/index.php/2392:_Cyber_Cafe

Which word in the name "cyber cafe" sounds more dated? 2015 - Cyber 2016 - Cyber 2017 - Cyber 2018 - Cyber 2019 - Cyber 2020 - Cafe

This comic is another in a series of comics related to the COVID-19 pandemic . A cybercafe, or Internet cafe , is a cafe or other restaurant that provides Internet access. Prior to widespread ownership of personal computers and cell phones, such cafes would host computers that clients could use, and nowadays, many fast-food restaurants and cafes provide free Wi-Fi to their customers, so that people can use their computers while at the cafe. "Cyber" is a prefix meaning something relating to computers (as in Cyber Monday, the day the comic was posted), but this comic suggests that it sounds dated, previously discussed in 1573: Cyberintelligence . However, in 2020, he jokes that "cafe" actually sounds more dated. This is a result of lockdowns related to the COVID-19 pandemic preventing people from going to cafes, and like the preceding comic is a play on the sense that the lockdowns could shift economies and cultures to remove parts of the physical world permanently, depending on how long they last. In the title text, Randall indulges his munchies of ambiguity by proposing that the term "cyber cafe" be re-used to refer to online hangout spaces that try to feel like cafes. This would change the meaning from "a cafe where computers are available for use by patrons" to "a setting or activity in cyberspace that feels like a cafe" (which would at least be inline with similar terms, like cyberbullying , cybersex , etc.). Which word in the name "cyber cafe" sounds more dated? 2015 - Cyber 2016 - Cyber 2017 - Cyber 2018 - Cyber 2019 - Cyber 2020 - Cafe

Presidential Middle Names

Presidential Middle Names

https://www.xkcd.com/2393

https://www.explainxkcd.com/wiki/index.php/2393:_Presidential_Middle_Names

Prettiest Presidential Middle Names Official Rankings (Updated for 2021)

A list of what Randall perceives will be the prettiest presidential middle names after the inauguration on January 20, 2021. Joe Robinette Biden (46th president-elect) will take the second slot bumping previous second-place holder Franklin Delano Roosevelt , the 32nd president, back to third. Warren Gamaliel Harding , the 29th president, remains in first. Robinette is Biden's grandmother's maiden name . The title text announces that Rutherford Birchard Hayes , the 19th president, remains at or near the bottom. Overall, the ranking would not include every president, as many early presidents, such as George Washington and John Adams , lacked middle names. Some presidents were also more commonly known by their middle names as opposed to their first names, particularly John Calvin Coolidge , Stephen Grover Cleveland , Hiram Ulysses Grant , and Thomas Woodrow Wilson . In the case of Grant, the Senator who enrolled him at West Point messed up his full name as Ulysses Simpson Grant, hence he is widely known as Ulysses S. Grant with the spurious middle "S". Also, Harry S Truman 's middle name was just the letter S and was not an initial of a name; Truman's parents could not agree on which of his grandfathers' names to give him, but luckily they both started with the letter. One president has even changed their entire name: Gerald Ford was born Leslie Lynch King, Jr., officially changing his name in 1935. There is no evidence in the comic for how Randall’s list would deal with these cases. The humor is based on the sheer oddity of ranking people by the perceived prettiness of their obscure middle names. Raphael Gamaliel Warnock became a U.S. senator in January 2021, a hundred years and a week after former president Warren Gamaliel Harding left the Senate. Randall’s favourite presidential middle name is thus once again represented in government. (updated for 2021, as the comic) The Presidents without middle names — almost all of those before Grant, and a few a bit later — were George Washington, John Adams, Thomas Jefferson , James Madison , James Monroe , Andrew Jackson , Martin Van Buren , John Tyler , Zachary Taylor , Millard Fillmore , Franklin Pierce , James Buchanan , Abraham Lincoln , Andrew Johnson , Benjamin Harrison , William McKinley , and Theodore Roosevelt . Prettiest Presidential Middle Names Official Rankings (Updated for 2021)

Contiguous 41 States

Contiguous 41 States

https://www.xkcd.com/2394

https://www.explainxkcd.com/wiki/index.php/2394:_Contiguous_41_States

[Heading above the panel:] The Contiguous 41 States [A map of the United States, missing Delaware, Kansas, New Mexico, Nebraska, North Dakota, Pennsylvania, and South Dakota, along with Alaska and Hawaii.] [Caption below the panel:] Tired of being left off maps of the US, Alaska and Hawaii begin producing maps with other states missing, too.

The United States of America is composed of 50 states, 48 of which are contiguous – meaning they share common borders. Two states are separated from the other 48 states, Alaska and Hawaii . Alaska, purchased from Russia in 1867, is separated from the rest of the United States by the country of Canada, or at least appears to be as a result of the Mercator Projection . Hawaii, annexed in 1898, is a group of islands in the Pacific Ocean. As these states are not contiguous to the rest of the 48 states, they may be omitted from maps of the United States. Typically, these 2 states are included in inset maps, separate sections usually placed at the bottom of the main map. The United States also includes 5 permanently inhabited territories (Puerto Rico, U.S. Virgin Islands, Guam, Northern Mariana Islands, American Samoa), which are not contiguous with states. Puerto Rico may become a state . The District of Columbia is not ( yet ) a state, but is contiguous with the states. The map in this comic is "Alaska and Hawaii's revenge", with seven additional states removed: North Dakota, South Dakota, Nebraska, Kansas, New Mexico, Pennsylvania, and Delaware. Most of these are accomplished by eliminating a column of states: North Dakota, South Dakota, Nebraska, and Kansas. Oklahoma and Texas, which are directly south of these, are slid over to the west into the space freed up by deleting New Mexico. The other two deleted states are Pennsylvania and Delaware, with the states to their south and north slid/extended to fill the gap. The map is also missing Isle Royale , Michigan, the third-largest island in the contiguous U.S. This seems to be a legitimate oversight, as the map includes numerous smaller islands in detail, including Michigan's Beaver Island and North Manitou Island. Even the non-contiguous Northwest Angle of Minnesota is depicted. (The Eastern Shore of Virginia , which is not connected to the rest of Virginia and only borders Maryland, is also not shown—presumably to make way for New Jersey replacing much of the Delmarva Peninsula ). Some states, while not removed, are significantly distorted. Iowa and Missouri lose their contours with the Missouri River, while Wyoming's eastern border is crooked. The eastern border of Maryland follows the Delaware river with New Jersey. The border between Oklahoma and Arkansas is moved west. The United States did have exactly 41 states for a few days in 1889, from the admission of Montana, the 41st state, on November 8, to the admission of Washington (the state, not DC), the 42nd state, on November 11. However, it was not the same 41 as shown here; for example, Pennsylvania and Delaware were two of the original 13 states (Delaware calls itself the first state, based on date of ratification of the Constitution) and Arizona and Oklahoma did not become states until the early 1900s. The title text riffs on synonyms for "shared borders", which, according to Randall, linguists are inventing more of (while claiming they already existed) to make life more complicated for modern English users, for obscure reasons. In fact, 'contiguous', 'coterminous', and 'conterminous' all date from early modern English, early-to-mid 17th century (just after the time of Shakespeare). 'Coterminous' and 'conterminous' are alternate spellings from the same Latin root ('cum' + 'terminus'), whereas 'contiguous' is from a different root (Latin 'contiguus'). Randall, facetiously, accuses linguists of having fabricated this history. 'Conterguous' is a neologism by Randall, though he blames it on linguists, consistent with his claim that they made up all the others. It is a portmanteau of 'CONTERminous' and 'contiGUOUS'. It is etymologically absurd (the prefix 'conter-' is meaningless). Its 'top-down' introduction into the language would simply be for the purpose of messing with people's minds, as Randall suggests. However, should the word catch on with English speakers, perhaps precisely because it is a joke, its 'bottom-up' entry into the language is certainly possible. One could then argue just how much Randall would have to answer for. [Heading above the panel:] The Contiguous 41 States [A map of the United States, missing Delaware, Kansas, New Mexico, Nebraska, North Dakota, Pennsylvania, and South Dakota, along with Alaska and Hawaii.] [Caption below the panel:] Tired of being left off maps of the US, Alaska and Hawaii begin producing maps with other states missing, too.

Covid Precaution Level

Covid Precaution Level

https://www.xkcd.com/2395

https://www.explainxkcd.com/wiki/index.php/2395:_Covid_Precaution_Level

COVID Precaution Level [Shown is a control knob for adjusting the stringency of precautions taken against COVID-19 (the knob has a black line indicating exactly where it is pointing), with fewer precautions to the left, more to the right. Most of the lower two thirds of the range is labelled "precautions that feel insufficient"; most of the upper two thirds is labelled "precautions that feel excessive". There is an overlap between the two, covering about 1/4 of the range. The control is set to somewhat above the top of the "insufficient" subrange.]

This comic is another in a series of comics related to the COVID-19 pandemic . This comic seems to represent the problem that precautions that are insufficient feel excessive to many people and vice versa, thus there is such a large overlap between the 2 sections. Even a moderately sensible individual will likely consider some blanket precautions restrictive because they don't allow a nuance of behaviour they think they should be able to embrace safely; meanwhile they'll find some of the actual official exceptions, that probably do not apply to them, to be taken reckless advantage of by others. Additionally, neither range mentions whether the precautions are actually effective, which also can have a level of subjectivity. Randall points out that part of the challenge with finding the 'right setting' is that you can only know for sure that your precautions were insufficient if and when you catch COVID and either get tested or develop symptoms, by which point it is too late to change your precautions (although your case could at least inform others). However, some people do not take precautions seriously even though they believe in COVID because they view it as a mild disease, like the common cold or influenza, that won't kill them, and there have been people who contracted COVID-19 multiple times, so perhaps Randall was referring to dying from COVID-19 instead. COVID Precaution Level [Shown is a control knob for adjusting the stringency of precautions taken against COVID-19 (the knob has a black line indicating exactly where it is pointing), with fewer precautions to the left, more to the right. Most of the lower two thirds of the range is labelled "precautions that feel insufficient"; most of the upper two thirds is labelled "precautions that feel excessive". There is an overlap between the two, covering about 1/4 of the range. The control is set to somewhat above the top of the "insufficient" subrange.]

Wonder Woman 1984

Wonder Woman 1984

https://www.xkcd.com/2396

https://www.explainxkcd.com/wiki/index.php/2396:_Wonder_Woman_1984

[Ponytail sitting at a desk, chatting with Cueball (off-screen) on a laptop.] Ponytail: Just two weeks until I see Wonder Woman 1984 , learn who the Democratic nominee was, and find out how the election went. Cueball: Huh? [Close-up on Ponytail.] Ponytail: To avoid spoilers, I blocked all news sites ahead of the November 2019 release. Ponytail: But then they bumped the date on my ticket to June 2020, and now December 25th. Ponytail: It also moved to a drive-in theater? Some retro promotion, maybe. [Cueball on his laptop, chatting with Ponytail (off-screen) on a laptop.] Cueball: Wait, you haven't seen any news? Ponytail: Nope! Cueball: So you don't know about - Ponytail: No spoilers! [Back to Ponytail sitting at a desk, chatting with Cueball (off-screen) on a laptop.] Cueball: Okay. Just... Cueball: Bring a mask, in case you need to get out of the car. Ponytail: Oh, I'll have a full costume! But it's a tiara, not a mask.

This comic is another in a series of comics related to the COVID-19 pandemic . Ponytail, who was eager to see Wonder Woman 1984 , the 2019 sequel to the acclaimed 2017 Wonder Woman film, decided to block all news media leading up to the film, to avoid spoilers . Avoiding spoilers is a common practice for people who do not wish to be "spoiled" by reading or hearing any plot points of the film, because they want to be immersed in the movie when watching it for the first time, by not being able to predict any plot twists before they occur. Many early reviewers may inadvertently give away key parts of the film, which may ruin the experience for some watchers, and story elements may be leaked by inside sources, either accidentally or deliberately. However, there have been many delays for release of the film, in part because of the COVID-19 pandemic in the spring of 2020. The film was originally delayed from November 1, 2019 to June 5, 2020 to allow more time for production, and then, after the pandemic struck, was pushed to August 14, 2020, then October 2, 2020, before it was finally moved to December 25, 2020. The film studio announced a simultaneous release of the film in theaters and also on streaming platform HBO Max . Absurdly, Ponytail apparently continued to block news sites after the delays, and so has not read any news in over a year, even news unrelated to movies. Because of this, she is apparently totally unaware of the entire pandemic, as well as more predictable major news items like the 2020 United States presidential election. This is particularly absurd, because these events were influential enough that it would be difficult or impossible to avoid awareness, even with no media exposure. They have been common topics of conversation, not to mention face-masks and other public health-control measures have now become ubiquitous, and election campaign signs and bumper stickers were common sights in the lead-up to November. How the release date being postponed (twice) did not convince Ponytail to find out why, therefore becoming aware of the pandemic with its associated lockdown and public health-control, is a question that is left unanswered. It is also unclear how she became aware that the movie had, in fact, been postponed. Her confusion as to why her movie is now being shown at a drive-in theater is a sign that she's unaware of COVID-19. Drive-in theaters have been seen as a safer option than indoor movie theaters during the pandemic. Cueball tries to warn her about the ongoing pandemic, but in an effort to avoid spoilers, she silences him. This may imply that in her wildly excessive effort to avoid spoilers, she's avoided leaving her home and talking to people, which could explain her exceptional level of disconnection from current events. Cueball then tells her to wear a mask, but she is still confused. Ponytail says that she will dress up in costume as Wonder Woman, who is traditionally shown wearing a tiara but not a mask (unlike Batman or many other comic characters, although efficiency of their masks still varies wildly in regards to COVID-19 protection). The title text expands on Ponytail's speculation that the use of the drive-in theaters is a "retro promotion," presumably because drive-ins and the '80s setting of the movie are now both considered to be retro in 2020. However, they are not associated with the same period; drive-in theaters in America had their heyday in the 1950s and '60s, and were in rapid decline by the '80s. Ponytail further demonstrates her misunderstanding of history by mentioning several other things which she wrongly believes are from the '80s. Britney Spears is a singer who was popular in the late 1990s and early 2000s. The Hustle was a disco dance popular in the mid-1970s. Pogs under that name peaked in the mid-1990s. Elvis 's appearance on the Ed Sullivan Show - a pivotal moment in American pop culture - occurred on September 9, 1956. ( The Ed Sullivan Show went off the air in 1971, Ed Sullivan died in 1974, and Elvis Presley died in 1977.) This joke concerns the phenomenon of people lumping together all time periods before their birth, which results in "retro" or "period" representations combining elements from widely different time periods. (A similar behavior is seen in 771: Period Speech .) Cueball points this out by asking Ponytail when she was born, implying that, if she'd actually lived through any of those time periods, she'd realize that they were distinct. If Ponytail could not remember any of these events in her childhood, an age of about 20 years can be set as an approximate upper bound for this particular character's age. This comic is similar to 2280: 2010 and 2020 and 2338: Faraday Tour , which also involve characters who are unaware of the COVID-19 pandemic. [Ponytail sitting at a desk, chatting with Cueball (off-screen) on a laptop.] Ponytail: Just two weeks until I see Wonder Woman 1984 , learn who the Democratic nominee was, and find out how the election went. Cueball: Huh? [Close-up on Ponytail.] Ponytail: To avoid spoilers, I blocked all news sites ahead of the November 2019 release. Ponytail: But then they bumped the date on my ticket to June 2020, and now December 25th. Ponytail: It also moved to a drive-in theater? Some retro promotion, maybe. [Cueball on his laptop, chatting with Ponytail (off-screen) on a laptop.] Cueball: Wait, you haven't seen any news? Ponytail: Nope! Cueball: So you don't know about - Ponytail: No spoilers! [Back to Ponytail sitting at a desk, chatting with Cueball (off-screen) on a laptop.] Cueball: Okay. Just... Cueball: Bring a mask, in case you need to get out of the car. Ponytail: Oh, I'll have a full costume! But it's a tiara, not a mask.

I Just Don't Trust Them

I Just Don't Trust Them

https://www.xkcd.com/2397

https://www.explainxkcd.com/wiki/index.php/2397:_I_Just_Don%27t_Trust_Them

[Cueball stands with his arms to his sides, facing Megan.] Cueball: I just don't trust them, and I don't want to put something they developed into my body. [Caption below the panel:] How I feel about bats

This comic is another in a series of comics related to the COVID-19 pandemic , specifically regarding the COVID-19 vaccine . Cueball partially echoes a statement made by anti-vaccination activists about " Big Pharma " (the powerful and profit-driven companies which develop pharmaceutical drugs such as vaccines ). Anti-vaccine protesters falsely believe that vaccines contain harmful toxins (such as HIV proteins, aluminum salts , formaldehyde, mercury , and nanoparticles) that cause ill effects on the human body, that just because there has never been a licensed mRNA vaccine before that these new vaccines are not safe in the long term, and that the corporations that make them are not to be trusted because they are exploiting a captive public for profit while disregarding public health. The joke is that Cueball is revealed to be not talking about Big Pharma but, instead, bats. According to the WHO, COVID-19 has an ecological origin in bat populations. Hence, Cueball sees the virus as something developed by bats, and the ambiguity by which he expresses his desire to not be infected adds to the joke. The comic could simply be seen to serve as a compelling argument against the anti-vaccine movement, which is often criticized for spreading misinformation and increasing rates of disease, especially since the start of the COVID-19 pandemic. This comic comes shortly after the news of the development of several COVID-19 vaccines with high rates of success; there are concerns that herd immunity may be delayed if people refuse to take the vaccine. The title text refers to getting immunity the old-fashioned way, i.e. catching the disease and waiting for your immune system to build up a response. This is usually considered healthy when immunity to minor diseases is common, and can avoid the sudden forced evolution of new diseases among extensively hypercareful communities, but developing natural immunity is certainly incredibly dangerous during a pandemic of a serious illness. One joke here is that many anti-vaxxers claim that it is more natural to not take a vaccine. Because many people conflate "natural" with "healthy", the assumption underlying the claim "it is more natural to not take a vaccine" is that it is therefore more healthy. Such arguments are an example of the logical fallacy known as Appeal to nature . Thus, the title text is apparently written from a pro-vaxxer's take on the stance of an anti-vaxxer. The title text also playfully suggests that the immune system would attempt to use an Internet search engine to learn how to manufacture spike protein antibodies . While this may be an effective technique for a human being to acquire knowledge, it would not likely be as efficient for a nonsentient biological system. [ citation needed ] [Cueball stands with his arms to his sides, facing Megan.] Cueball: I just don't trust them, and I don't want to put something they developed into my body. [Caption below the panel:] How I feel about bats

Vaccine Tracker

Vaccine Tracker

https://www.xkcd.com/2398

https://www.explainxkcd.com/wiki/index.php/2398:_Vaccine_Tracker

[Megan walks towards Cueball. Cueball sits in front of his laptop.] Megan: What are you up to? Cueball: You know how when I have a package coming, I sit here refreshing the package tracker? Megan: Is that the state vaccine website? [Cueball refreshes the page] *REFRESH* Megan: You know it will be a while before you can- [Cueball refreshes the page, cutting her off.] *REFRESH* Megan: They haven't even announced when- [Cueball refreshes the page again, cutting her off.] *REFRESH* Megan: Are you going to sit there clicking refresh for several months? Cueball: I am ready for the pandemic to be done.

This comic is another in a series of comics related to the COVID-19 pandemic , specifically regarding the COVID-19 vaccine . Similar to 281: Online Package Tracking , Cueball is trying to "track" the status of the Pfizer COVID-19 vaccine , which was approved in the USA the week prior to the publishing of this comic, and began to be administered the day of publication. Cueball is impatient for the vaccine to be released to the public, wanting the pandemic to end as soon as possible. Because of that, he is treating the state vaccine website like a package tracker, even though it will probably be several months before he is vaccinated. Of course, the state vaccine website does not act like a package tracker, and updates will be few and far between. The comedy in this comes from Cueball expecting it to update regularly, even though the vaccine is not going to come anytime soon for most people, especially for those in Cueball's presumed priority level. Checking once a day for general 'movement' probably would more than suffice to get a head's up on when a possible invitation or opportunity to book would present itself. The title text refers to Pfizer's vaccine plant in the city of Kalamazoo, Michigan , and is also a reference to 281: Online Package Tracking . [Megan walks towards Cueball. Cueball sits in front of his laptop.] Megan: What are you up to? Cueball: You know how when I have a package coming, I sit here refreshing the package tracker? Megan: Is that the state vaccine website? [Cueball refreshes the page] *REFRESH* Megan: You know it will be a while before you can- [Cueball refreshes the page, cutting her off.] *REFRESH* Megan: They haven't even announced when- [Cueball refreshes the page again, cutting her off.] *REFRESH* Megan: Are you going to sit there clicking refresh for several months? Cueball: I am ready for the pandemic to be done.

2020 Election Map

2020 Election Map

https://www.xkcd.com/2399

https://www.explainxkcd.com/wiki/index.php/2399:_2020_Election_Map

2020 Election Map [One stick figure in a black circle] = 250,000 votes [Stick figure in a blue circle] Biden [Stick figure in a red circle] Trump [Stick figure in a green circle] Other Votes are distributed by state as accurately as possible while keeping national totals correct. Location within each state is approximate. [Blue, red, and green circles are distributed across a map of the United States.]

This is a sequel to an earlier comic, 1939: 2016 Election Map . The United States elects its president not directly by popular vote but by an Electoral College composed of a number of electors, partially proportional to population, from each state. Presently, a "winner-take-all" system is used in most states: the winner of the popular vote in each state receives all of the electoral votes for that state. Though, strictly speaking, the electors are not required to cast their ballots according to this system, many states impose penalties on them if they don't. Technically, the popular vote in each state is to elect a slate of electors who in turn elect the President. During the election season, news outlets and other political trackers tend to color-code each state with the party which won the state (or which is projected or speculated to win). Since the 2000 election it's become common practice to code Republican victories as red and Democratic victories as blue. Other parties have less consistent colors, but are commonly green. These colors have become embedded in popular vernacular, as states that are heavily Republican are known as "red states" and those that are heavily Democratic are known as "blue states". These graphics can be misleading as to the realities on the ground, though. Because each state is colored solidly red or blue, it gives the impression that each state belongs entirely to one party or the other, when the color could represent a very slender minority, or an overwhelming advantage. In addition, such a graphical view means that larger states translate to more area of a given color, giving the impression of party strength, even though that may not represent many voters. In the US, large cities trend largely Democratic, while rural areas trend largely Republican. This means that many Democratic voters are concentrated in relatively small urban areas, so a large "red" state may represent fewer voters than a small "blue" state. Randall's solution to this is to represent the Republican and Democratic voters in each state with Cueball icons, each icon representing 250,000 voters. He has made some attempt to distribute the Cueball icons within a state in a manner similar to how the actual votes were distributed. This has the advantage of giving a decent impression of how popular each candidate was, how their popularity varied across the country, and how the votes were distributed by both state and region. It also gives at least a basic indication of population patterns in the US, with large regions that are sparsely inhabited, and populations clustered in urban centers. The title text compares different voter pools in terms of absolute size. These facts are frequently counter-intuitive. California is generally thought of as a "blue state", and Texas as a "red state" (Although that may be changing), so it's surprising to realize that, in 2020, Donald Trump received more votes in California than he did in Texas. The reason for this is not complex, California has a huge population, nearly 40 million people, of whom 17.5 million voted in 2020. Even though Joe Biden won the state easily, Trump received 6 million of those votes. Texas, by contrast, has 27.7 million residents and 11.3 million voters in the 2020 election. Trump received 5.9 million of those votes, which was enough to win the state. Because of the huge variation in population among US states, and the political divisions within each state, there are multiple "blue" states which have more Republican voters that at least some "red" states, and vice versa. This underscores the importance of not viewing any state as politically uniform. Even if a state trends heavily toward one party, there is always a substantial population of the other party, and in large states, that means enough people that they'd be a formidable political force anywhere else. Source The following table lists the number of 250,000-vote markers in the map by candidate and state, and compares this with the actual number of votes. Source 2020 Election Map [One stick figure in a black circle] = 250,000 votes [Stick figure in a blue circle] Biden [Stick figure in a red circle] Trump [Stick figure in a green circle] Other Votes are distributed by state as accurately as possible while keeping national totals correct. Location within each state is approximate. [Blue, red, and green circles are distributed across a map of the United States.]

Statistics

Statistics

https://www.xkcd.com/2400

https://www.explainxkcd.com/wiki/index.php/2400:_Statistics

[Shown is a graph with the x-axis labeled "time" and the y-axis labeled "COVID cases." There is a black line on the graph labeled "placebo group", which has a roughly linear slope moving toward the top right corner. There is a red line labeled "vaccine group", which follows the black line for about an eighth of the width of the graph before leveling off at a much slower increase.] Caption beneath the graph: Statistics tip: Always try to get data that's good enough that you don't need to do statistics on it

This comic is another in a series of comics related to the COVID-19 pandemic , specifically regarding the COVID-19 vaccine . It is also another one of Randall's Tips , this time a statistics tip. The main focus of the comic is a graph showing cases of COVID-19 versus time for two groups: one group was vaccinated and the other group was not. Graphs are ways to visualize data, and for real data indicate specific values. This graph seems to be based on the Moderna vaccine's results but is somewhat fictionalized. The higher line ("placebo group") rises in a steep curve. The lower line ("vaccine group") follows the first for a bit but then levels out to a much slower rate of climb. Officially, a scientific assessment of the effectiveness of anything requires rigorous statistical analysis. This is particularly true in medical studies, where impacts of biology can be highly complex and subject to many factors, meaning that careful review of the data is necessary to confirm that an intervention was effective. The joke of this comic is that the intervention presented here is so obviously effective that it's obvious even to a layman with little understanding of the math. A few days after the vaccine was administered, cases in the vaccinated group essentially flatline, while cases in the placebo group continue to rise as a significant rate. The data is so "good", meaning that numbers for the treatment and control groups diverge so dramatically, that actual analysis becomes almost a formality: a glance at the chart would convince most people that the treatment is effective. This comic was released one day after the FDA's Dec 17th briefing document for the Moderna COVID-19 vaccine was released. The document includes the following chart . The charts draw the integral of the incidence data rather than the data itself ("cumulative" rather than "rate"): this results in changes in disease rate towards the left side of the chart, being added into the data on the right side, amplifying their difference. This technique for emphasizing the data is valid: the spread between the lines only continues to increase if the effect continues happening, such that the total spread at the right is proportional to the total effect the vaccine had. The charts do not show any information on other possible variables. Randall has described previously in his webcomics how very clear charts can be made to hide misleading data. The linked graph does not leave the numbers out, and the numbers indicate the vaccine is 91% effective at preventing the disease (and a 95% chance of being between 85 and 95% efficient). The advice here could be seen as the inverse of the "science tip" in 2311: Confidence Interval , in which the data was so bad that its error bars fell outside of the graph and were not shown. Also there's some association with 1725: Linear Regression where the data is not so good that you don't need to perform linear analysis. The null hypothesis, mentioned in the title text, is the hypothesis in a statistical analysis that indicates that the effect investigated by the analysis does not occur, i.e. 'null' as in zero effect. For example, the null hypothesis for this study might be "The vaccine has no effect on whether subjects catch COVID." The null hypothesis was previously the subject of 892: Null Hypothesis . The null hypothesis is rejected when the probability of something like the observed data would be very low were the null hypothesis true. For a simplified example, imagine there are 10 000 people in the vaccinated group, and each has a 5% chance of catching COVID under the null hypothesis; we expect 500 people to catch COVID. If only 490 catch COVID, the null hypothesis remains plausible, but if just 10 do, the odds are (in Python; see binomial distribution ) sum([math.comb(10000, i) * 0.05**i * 0.95**(10000-i) for i in range(0,10)]) = 1.5 × 10 -204 . In other words, it is wildly improbably that an ineffective vaccine would have produced such excellent results. We therefore conclude that the vaccine is not ineffective, and have rejected the null hypothesis. Most people however, on seeing the raw results, would have concluded that the vaccine worked and statistics were just a formality. As the title text says, they would have "reject[ed] the null hypothesis based on the 'hot damn, check out this chart' test." [Shown is a graph with the x-axis labeled "time" and the y-axis labeled "COVID cases." There is a black line on the graph labeled "placebo group", which has a roughly linear slope moving toward the top right corner. There is a red line labeled "vaccine group", which follows the black line for about an eighth of the width of the graph before leveling off at a much slower increase.] Caption beneath the graph: Statistics tip: Always try to get data that's good enough that you don't need to do statistics on it