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When I stay in bed for 10 more minutes after I wake up, why does it sometimes feel like eternity, and sometimes like less than a minute? | [
"Im pretty sure its because you actually fell back asleep those moments it seems to go by in a flash... because you lost consciousness."
] | [
"Similar questions have been asked several times before. You may be interested in the following posts: _URL_3_ _URL_8_ _URL_6_ _URL_0_ _URL_1_ _URL_4_ _URL_7_ _URL_2_ _URL_5_ _URL_9_ There are lots of really great questions and answers in /r/askscience that unfortunately get buried because of the high volume. It's a bit tricky to get exactly what you are interested in by using the searchbar, but I find that using 2 or 3 words (like \"time perception\" or \"brain time\") can lead to relevant posts."
] |
How dangerous is uranium/uranium oxide to handle? | [
"It's relatively safe to handle. It's weakly radioactive and is primarily an alpha particle emitter. Alpha particles are very large so they can't really penetrate your outer layers of dead skin to damage living tissue. Just wash your hands afterward. It is a heavy metal, like lead, afterall. As for the long half live = less radioactive part you should think of it like this. You have two materials. One with a half life of 2 seconds and one with a half life of 2 billions years. The short half life material would undergo the same amount of decay in 2 seconds as the long half life material would over 2 billion years. Both materials will release the same amount of radioactive particles over their lifetime, but the short half life material will do so at a much MUCH shorter period."
] | [
"Not to be Dickhead McBuzzkill here, but if any of you do or have actually worked with classified information, please be aware of what you are posting. It is fairly easy to violate your NDAs, and something as simple as \"I work for X and know Y\" may get you into more trouble than it is worth, especially if you want to keep access that you currently have. Remember, even Unclassified info can and most often is FOUO. Additionally, you are putting a large target over your head for many intelligence gathering entities worldwide. Yes, the public should know the rules, but I highly suggest you redirect those questions to official channels or publications. Please be OPSEC aware as well. TL;DR be careful what you say, pic if you forgot. _URL_0_"
] |
I find that, in general, people in Western societies tend to be very selective in who they invite in gatherings and will often not make their invitations open to people outside their social circle. Is this a cultural thing? | [
"Is this different in non-western societies? Like, I know for example that in many places in India weddings are events for the whole community and stuff like that. I've never really heard that, generally, non-Western societies are extremely open in the attendance of social events."
] | [
"Part is cultural. Part is barrier to entry. The great thing about the internet is that anyone can add to it. Part of what sucks about the internet is that anyone can add to it. Creating a podcast is easy, shooting a youtube video is relatively easy, making a webpage is fairly easy. Publishing a full length book is still probably the hardest. While self publishing has increased, the maajority of works you see out there still went through a professional publisher choosing a writer they thought reputable, going through an editing process, etc. More work is done upfront to make the work accurate because once published it is harder to change than a website for example. The existance of \"gate keepers\" in book industry is partbof what makes it more respected. That said, tradition and cultural significance come intonplay too."
] |
Meats having a more popular/restricted way of cooking/eating them. | [
"Those are more guidelines derived from sanitary rules/taste. Chicken can be eaten raw, but you risk salmonella infection; beef would probably have consistency of a brick if you deep fry it and so on. Stir-fried fish exists though, don't know why you thought it doesn't, Chinese cuisine stir-fries just about everything."
] | [
"If i'm not mistaken, the law forbids promotion of non-traditional sexual relations among minors. That itself is absurd, but the bigger problem is that the text of the law is so ambiguous that any public expression of \"non-traditional love\" o even any public comment can be punished. (Sorry for my english, not my native language and i'm trying to do my best)"
] |
Help identifying a Japanese battle flag from WWII | [
"I can't read all of it--the vertical text on the sides is quite difficult and I will leave it to somebody else. But the text on the top 国報身 献、is a wartime slogan that means something like 'serve the country, give up one's body' and the name of the soldier on the bottom horizontal text, I think, is Hisanaga Takeshi. It also gives the family name of the Lieutenant General of his unit (I'm assuming), which was Tominaga and would probably help in locating his family. It's also dated Showa 18 or 1943."
] | [
"Reminder: This is AskHistorians, not AskRandomPeopleWhoCanGoogle. If you do not have in-depth knowledge of the level expected of a historian, whether amateur or professional, do not post. Thank you."
] |
How do sperm cells know in what direction to swim in order to reach the egg cell? | [
"It's thought they are following a gradient of molecules released by the egg; [Chemotaxis](_URL_0_)."
] | [
"A lot of it would be smell and pheromones wouldn't it? That's why male dogs go nuts when female dogs are in heat - they can smell the pheromones they're giving off (from some distance away I might add)."
] |
What is minimum amount of people needed to have the genetic diversity available to populate the entire world? | [
"It depends on how long you're willing to wait, and how much death and genetic diseases you're willing to tolerate. The absolute minimum is two fertile people - one male and one female. yes, you would have genetic problems with a larger than ideal portion of their grandchildren. As these die and the remaining mutate and spread over the next few hundred thousand years, humans will repopulate. You get a huge benefit of having a second couple of drastically different genetic makeup, but you continue to get more benefit as you get more people either way. There is also no maximum diversity or ideal diversity that I'm aware of. Humans are already less diverse than many other species."
] | [
"Here's something I didn't see referenced in the three posts linked in the FAQ. There's a genetic mutation called Delta 32 or [CCR5](_URL_1_) that is believed to impart resistance to the Bubonic plague (and possibly HIV). Apparently this gene is more prevalent in Scandinavian and Slavic bloodlines. There's another article about it [here.](_URL_0_)"
] |
How a sinus infection is not contagious even though the person affected is constantly coughing/sneezing/dribbling snot everywhere? | [
"Because a sinus infection isn't caused by a specific bacteria. Like there isnt a bacteria that you can consume/inject etc that will then give you a sinus infection. A sinus infection is caused by blockage of the sinuses that then causes the bacteria in there to go crazy. The bacteria isn't really the cause, the initial blockage was. Unblocked the bacteria would have been kept under control"
] | [
"Just because it isn't raining on you doesn't mean it isn't raining somewhere else. Moisture in the air also does not automatically equal rain. That would be humidity. It takes other weather patterns, frontal systems, etc to determine when and where rain falls from the sky."
] |
how come the rings of Saturn orbit on a flat plane around the planet, as opposed to evenly spread out? | [
"Same reason why the planets are in a relatively horizontal plane around the sun. Angular momentum is conserved, so as orbiting materials collide, they eventually settle into a disk. What conservation of angular momentum means, is that the total sum of each particles momentum, must but equal to their ending momentum. So you get a lot of chaotic collisions when the cloud first starts, but as more and more collisions take place, more and more of the upward and downward momentum is converted into horizontal momentum. This creates the plane or disk."
] | [
"Basically it's because the silicon-oxygen bond is extremely stable, compared to pretty much everything except for silicon-fluorine. /u/coniform answers it more thoroughly: _URL_0_"
] |
Why did the Vietnam war last for so long, and why did it end the way it did? | [
"With regards to which part? Is this question referring to the US involvement which ends in 1973 or the conclusion and fall of Saigon in 1975?"
] | [
"Look at it like a chess board: After 100+ moves, it's hard to set every step back until you're in the start position. It's easier to remove all the pieces from the board and start all over. ^This ^was ^explained ^before"
] |
If there is so much crisis for oil in the world, why are motorsport events like f1 still being held? | [
"The amount of oil that motorsports use are minuscule compared to what average, everyday drivers use. Also, oil companies tend to sponsor motorsports too, so the oil-producers are making money too."
] | [
"When we do the same mundane task over and over and over, our brain basically shuts off. We just continue doing the mundane task as a brain \"sub routine\" and we drift out. Car accidents are exciting and different, it wakes your brain up. Something is happening so now you're active in your involvement in driving. So you look at it. Plus we are social animals and pay attention to humans in extreme situations. Just regular humanity stuff."
] |
Where does the sulfur in meromictic lake environments originate? | [
"Most oxic groundwater will have some sulfate mostly derived from oxidation of pyrite which is ubiquitous. Pyrite oxidation is the single most important source of sulfate in river waters. It can also come from dissolution of sulfate minerals from the surrounding rocks or groundwater. Perhaps the best studied meromictic lake in the US is called Fayetteville Green Lake. It is a glacial plunge pool lake and is pretty much a very deep cylinder. It has a deep groundwater source that picks up sulfate from the local limestone that has some evaporite minerals. It is very sulfate rich for a lake and is actually slightly saline at depth. Sulfate is also present in carbonates as a substitution for the carbonate ion."
] | [
"While technically off-topic, you might be interested in also learning more about melting permafrost and its [impact on methane emissions](_URL_0_)."
] |
Why does shaving work better with hot water than with cold? | [
"The warm water opens up the hair follicle in your skin so that more of the hair is exposed and you can get a closer shave."
] | [
"This is called \"Temperature-dependent Sex Determination\" or TSD for short. In a developing embryo inside of an egg there are multiple enzymes responsible for facilitating the genetic development. Think of it as the Embryo has the blueprint, and the enzymes are the construction workers. For these birds and reptiles with TSD, hormones control what gender they are. It is theorized that a particular enzyme called **aromatase** which converts testosterone to estrogen (predominantly male hormones to predominantly female hormones) is less active at lower temperatures, where-as at higher temperatures it becomes much more busy and converts a lot more hormones which affects the gender of the reptiles. So at lower temperatures the embryo contains more testosterone which allows it to develop male chromosomes and at higher temperatures this is converted to estrogen which allows it to develop female chromosomes."
] |
Was slavery legal in the Italian city-states in the early 15th century? | [
"Different cities had different laws regarding servitude. If Maddalena had been clever, she would have bolted from Cosimo's entourage once she was in sight of Bologna. u/Enrico_Dandolo and I had [a discussion about the Italian slave trade here.](_URL_0_)"
] | [
"hi! Could you clarify the scope of this question? Are you mainly asking about practices in Scotland / the British Isles roughly around the Civil Wars, or landowners anytime anywhere? [hint: [say the former](_URL_0_) ]"
] |
Why do people cut themselves? | [
"A couple of reasons: 1. Inflicting pain *can* trigger a release of endorphins, which are basically \"feel-good\" chemicals in your brain. So, given that many cutters are experiencing psychological issues, this can be one way of getting endorphins that are otherwise not being produced or absorbed properly. 2. As a sign to others that they really need help and are seriously ill. A lot of people with severe depression have a very hard time talking about it, and these actions are cries for help that the person would otherwise be unable to actually make."
] | [
"Cat claws grow in layers, like an onion. When they scratch, they are stripping away the worn outer layer to expose a fresh, sharp one underneath. I have a lot of cats and often find the discarded claw sheaths left on the carpet."
] |
Why did Google become the most used search engine? | [
"The founders of Google invented a cool mathematical algorithm (called PageRank) that produced much better search results than all of the other search engines available at the time. Before Google, you were lucky if the page you were looking for showed up in the first 10 pages of results. After Google, it usually showed up as the first result, making it much easier to find what you were looking for. Plus, they made their search page very simple and clean, so people started using it as their home page instead of more messy and annoying pages like Yahoo. I used to use Lycos back in the day. Those were innocent times."
] | [
"As big as they seem they are not covering majority of the population. Their are entire states were they dont have service in. Like most cable companies they are one of 2 choices in most areas. Dont forget you can get satellite in 98% of places which is a choice.. not the best choice but a choice."
] |
Why do I like toasted bread, but not stale bread? | [
"It is due to a reaction called the Maillard reaction, which is a non-enzymatic form of browning which is caused by heat. It is a chemical reaction between amino acids and reducing sugars. Maillard reactions are why we like browned meat, roasted coffee and biscuits (most baking processes go through the maillard reaction). Caramelisation is a completely different reaction and is only the reaction of sugars. However, they may both occur in the same foods and cause the same browning and flavours in some cases. With toasted bread it is the Maillard reaction that is the main influence on preference. Staling is caused by starch granules losing their water content, which creates more linking between starch molecules causing recrystallisation. This causes the dryness and leathery feel to stale bread, which are deemed undesirable in most cases."
] | [
"Context. The thought was formed in one environment and an association created. When you pass through a doorway you're passing into a new context and the association is lost."
] |
Does the Baby Boomer vs. Millenial feud exist outside of the US? Why (not)? | [
"It exists everywhere. Old people think the young are impulsive and irresponsible and the young think the older generations are boring and holding society back. Before Gen X and the Millenials the Boomers were seen as lazy by their elders. It's a cycle. Eventually us Millenials will be calling whatever the young gen will be called the same thing."
] | [
"Could you clarify what country you're from? That will have a lot to do with it. Different countries had different levels of involvement and remember the two periods differently. Additionally, there's an AMA about WWI and WWII where you might find tour answer. But again you'll need to specify where you're from."
] |
How computers handles large numbers. | [
"There are two ways. Your calculator likely uses [floating point arithmetic](_URL_0_). Instead of holding the number as-is, it holds two numbers - the mantissa (m) and the exponent (e) - which represent the number m\\*2^(e) (and one extra bit is used for the plus/minus sign). The number 2^64 is can then be represented using m=1 and e=64. It is also possible to represent large numbers in software with an array of numbers. Just like we can represent number of any size using a series of digits, you can for example represent 64 bits with two 32-bit numbers - the 1st number represents the higher order bits and the 2nd number represents the lower order bits. This makes the arithmetic a bit complicated of course - when you add two numbers, first you add the lower order bits, figure out what the carry would be, and then add the higher order bits along with the carry. You can use the same method to represent number of any size (96 bits are three 32-bit numbers, and so on)."
] | [
"Servers - lots and lots of servers. As an example here's a link to some images of [google data centres](_URL_0_)"
] |
Orange seems to be the national color of the Netherlands, so why isn't it on their flag? | [
"It used to be _URL_3_ But during the French occupation between 1795 and 1813 it was changed to red because the House of Orange was on the English side and the French didn't want a reference to house of Orange. In the 1920's end 1930's it was considered to move back from red to orange. However, only the Dutch naziparty NSB was completely supportive on this. Because the then queen Wilhelmina didn’t like the NSB she’s blocked this. Since then the version with orange instead of red is associated with (neo-)nazis. In situations that are asociated with the Royal house, like queensday, a orange pennant is added to the flag."
] | [
"The change came with the meeting between Nixon and Mao. Reading up on that meeting might be a place to start. The relationship between China (PRC) and Taiwan (ROC) is interesting. Both governments consider them to be one country. As long as the exiled-government-of-China-which-resides-in-Taiwan continued (and continues) to believe itself to be the true government of China, it wasn't and won't be possible to have one seat for China and another seat for Taiwan. China agrees that they are one country but that Taiwan is a rogue province that will not accept the true government which is that of China. There cannot be two seats as long as they both believe there is only one country and that each of their governments is the only true government. When I heard the news of what was happening with Nixon, the common belief was that the US could no longer ignore the huge market that China provided. Nixon seemed to know how to talk to Mao. More than that I can't tell you."
] |
After seeing the "failed" GTAV online, and the long history of MMO launch day fails, what can't developers learn from their mistakes, or what is different in the following days that finally makes it work? | [
"Learning from them is easy - you either design your system and provision servers based on the idea that everyone who uses your system will do so all at the same time, or you make the reasonable assumption that once launch day is over users will not spend 24 hours a day on your system, prepare for that scenario and have launch day issues. Because the former has enormous monetary costs attached for no immediate benefit (the users have already paid, remember), companies choose to instead have launch day issues."
] | [
"Muscle memory and learning. You don't instinctively know exactly how to throw a baseball to get it on target as a toddler. You can get it in the general direction, but only through practice and the brain having an opportunity to learn through experience do you become capable of throwing a ball accurately"
] |
How do contraceptive pills work when taken consecutively? | [
"To become pregnant you need a proliferated endometrium, your ovaries to release an egg (ovulation) and the sperm to reach that egg. All of the various contraceptives interfere with one or more of these processes. The combined oral contraceptive pill prevents ovulation by keeping the hormones progesterone and oestrogen constantly high. This prevents the usual spike of leutenising hormone (LH) and follicle stimulating hormone (FSH) from happening that would usually release an egg. The LH and FSH spike is triggered by the fall in oestrogen mid-cycle. Keeping oestrogen and progesterone high means that no egg is released. The pills have to be taken regularly or there will be a drop and the cycle will restart quickly. When starting or restarting them, the hormones take a while to build up to adequate levels which is why the advice is to use barrier protection for 7 days on top of the pill, as in this period an egg could be released. Source: I am a Medical Student"
] | [
"Antiviruses hook system calls to add their verification routines. System calls addresses are stored in the system service dispatch table (SSDT). Simply put, when a program wants to open a file, it tells Windows \"Open file.txt please\", and Windows looks at the SSDT where is the function to open a file, and calls it. An antivirus replaces the original \"open file\" function by its own, which after opening the file, check its content to see if it's fine. This considerably slows down the operation. When multiple antiviruses are installed, verifications are chained, so the slowness increases. Additionally, antiviruses don't like programs which modify the SSDT, including... other antiviruses. Since this is kernel space, anything that goes wrong will cause a blue screen, so you don't want multiple antiviruses to fight in kernel mode."
] |
Were duels really a big thing in wild west America like movies would have us believe? | [
"More can be written, but you might like to read [\"How common were western movie style shoot outs and duels in the wild west?\"](_URL_2_) , with answers by /u/gamblekat [here](_URL_0_), /u/verticaljeff [here](_URL_2_c7w2yxd/) , \\[deleted] [here](_URL_2_c7w31ij/), and to some extent /u/SnowblindAlbino [here](_URL_2_c7w5h6z/) (though that one is more about violence in general). However, note that the rules 5 years ago were looser, so there's a large amount of fluff in there -- the replies I've marked are the ones that I think are applicable and of good quality. As an aside: if you're interested in the \"Wild West\" more generally, this is from an FAQ section ['How historically accurate ... are \"Wild West\" tropes?'](_URL_1_) . This is not to discourage discussion. More questions, data, and debate are welcome."
] | [
"hi! Could you clarify the scope of this question? Are you mainly asking about practices in Scotland / the British Isles roughly around the Civil Wars, or landowners anytime anywhere? [hint: [say the former](_URL_0_) ]"
] |
How could I "timestamp" a physical letter such that later on I can prove it was created at a certain date? | [
"Send it to yourself via regular post. The postmark will indicate the date. Note that this will not protect your idea though. Patents rights are granted on a first to file basis, rather than first to invent. The only way to invalidate a competitor's patent is to prove that the information was in the public domain prior to their application, which a sealed letter doesn't do."
] | [
"You can measure inflation using a price index. Record how much companies charge for a bunch of different kinds of goods and services across all parts of the economy. Track it over time. If one person burns a $100 bill as a joke, the signal will be weak and lost in the noise. If someone is burning massive piles of millions of $100 bills, the signal will eventually show up as lower prices in those price statistics. When the guys at the Federal Reserve (the organization in charge of the money supply in the US) see those prices going lower, they'll buy up government bonds, which in effect is printing money for the system."
] |
Why did these metronomes eventually sync together? (see video) | [
"When they are started, they have a net momentum. Over time, the momentum is redistributed until each metronome has the same amount. They are coupled together by the board, and that's placed on the almost friction-less beer-can rollers. Each metronome has the average motion fed into them through their base, and this adds or removes energy to sync them up. Any excess is lost to air friction and any shortage is made up by the metronome's spring. It's a great physics demo."
] | [
"You may be interested in some of the earlier answers and journal papers linked in this recent thread (there's one anthropological paper that's particularly interesting re. chronotypes): (_URL_1_) by u/whattthefat and myself. u/sunagainstgold on how [muezzins and medieval monks woke up](_URL_0_) There are also a few older answers in the FAQ: _URL_2_"
] |
Do particles on a spinning disk experience time dilation? | [
"Yes. This was tested when they flew two atomic clocks in opposite directions around the Earth, and is important for calculating positions using GPS satellites."
] | [
"It is much more complicated than that, and is a very active area of research. A professor at my school, David Eagleman, studies this stuff. He's a complete badass, check him out: _URL_0_ edit: one of his famous experiments involves using magnetic energy to slow the propagation of some signals in the brain, and if done properly it can make you think cause and effect are reversed in some special circumstances. he also dropped grad students from a tall structure with a quickly-blinking watch to see if the fear of death would help them see what the watch was displaying. they couldn't. many biological reactions happen just as fast or faster than nitroglycerin degradation. something like time perception that involves consciousness must by definition be related to higher-order neural networks in the brain."
] |
If air is made up of millions of molecules, why can we see through them? | [
"Sight works on light reflecting off of a surface and stimulating receptors in your eye that convert these stimuli into a signal that your brain can understand. These molecules do not reflect enough light for the receptors in your eyes to be stimulated."
] | [
"But wouldn't you then end up with a blacked-out object, instead of it being invisible, i.e. transparent? Edit: To expand, if you want something to become functionally transparent, you have to bend the light around it, so that it appears as if it wasn't there. Magicians do that (or trick you otherwise) using mirrors, and at least at single wavelengths, [there exist designs that can bend light accordingly.](_URL_0_) Somthing similar has also recently been [demonstrated experimentally in the microwave range.](_URL_1_) But we're still far from an actually working, full-(visible-)spectrum, 3d invisibility cloak."
] |
Why does putting bread into hard brown sugar soften it? | [
"It adds moisture without making the sugar wet keeping the molasses from crystalizing"
] | [
"Angles my friend. Try taking a knife and sliding it across a piece of fruit like a razor, then try the same thing smashing it perpendicular. One won't do a damn thing, the other slices the fruit wide open."
] |
If whales breath oxygen, why will they die so quickly if beached? | [
"I believe the suffocate. They weigh so much that they are unable to properly breathe out of water. Something similar to you being unable to breath if someone is sitting on your diaphragm. Also, I would imagine the vast difference in temperature between water and atmosphere would do them harm."
] | [
"You're right to be confused. It is 100% wrong as depicted in the movie, and a lot of people of wondered about why they made such a grave error considering the rest of the movie was *somewhat* realistic. It is likely that the reason this happens in the movie is that it makes things more dramatic. Artistic license is a real thing, and directors often employ it for emotional or dramatic effect. It bugs us science types, but that is the world we live in!"
] |
How can touch lamps be sensitive to touch while simultaneously being grounded/earthed? | [
"There can be a touch surface which is grounded via a low resistance inductor. The inductor would not prevent the low level, high frequency signal used by the touch sensor from working. Inductors (block or reduce) the flow of AC."
] | [
"> Nothing about it makes sense to me. How does this work? It is simple: Saps pay money for a red LED light and believe any pseudoscientific nonsense that is tossed their way. The scam artist makes a load of money off this fad. Of course it doesn't do anything, there is no evidence that the \"therapy\" works, but that doesn't stop them being really popular with those who don't have the ability to assess the truth value of health claims. You know, like people who go to chiropractors or take homeopathic remedies."
] |
How does a nuclear power plant work? | [
"[HowStuffWorks](_URL_0_) In short, they use nuclear fission to generate a lot of heat. This heat is then pumped into water, turning it into steam. The steam is then directed so that it spins a turbine which generates electricity. The only major difference between nuclear power and something like coal or natural gas is how the heat gets generated. They all use heat to generate steam, which spins a turbine to create electricity."
] | [
"Are you talking about the [nucleon-nucleon potential](_URL_0_)? The repulsive core comes from Pauli exclusion between the quarks. If you have two nucleons very close together (less than 1 fm), you can think of the wavefunctions of the valence quarks overlapping strongly. Because quarks of the same flavor are identical fermions, Pauli exclusion prevents them from occupying the same state, and causes an energy cost when they're brought into similar states."
] |
How do erasers work on a molecular level? | [
"rub eraser on paper. friction roughens the paper fibres and creates heat. Heat makes rubber sticky. Sticky the rubber picks up the graphite"
] | [
"I had the same question, but I hit the google and got this. > NASA programs previously used pencils[6] (for example a 1965 order of mechanical pencils[7]) but because of the substantial dangers that broken pencil tips and graphite dust pose to electronics in zero gravity, the flammable nature of wood present in pencils,[7] and the inadequate quality documentation produced by non-permanent or smeared recordkeeping, a better solution was needed. [_URL_0_](_URL_0_)"
] |
Parvaneh Pourshariati's book "the decline and fall of the sassanian empire" and its impact(or lack there of) | [
"I have not read her book and it's probably too recent (2 years old) for serious rebuttals or the like to have emerged. But if there are particular aspects of her thesis that you could recount I could possibly recommend you works on that basis and/or adress how \"mainstream\" they are."
] | [
"Hi, I've approved the post, but just a note to you and potential respondents: this subreddit has a 20-year rule against discussing current events, so any answers will have to cut off at 1997. If you're looking for answers that can include 1998-2012, do consider x-posting elsewhere, eg. a foreign affairs sub like /r/geopolitics"
] |
How did the first cell know how to reproduce? | [
"> When life started, how was that cell able to replicate? First off, these are completely different things. The first life was not cells by the way we use the term today. [Organics](_URL_0_) form naturally from non-organic carbon, etc. The first ~life~ would have been [protocells](_URL_2_) and self-replicating RNA strands. You're looking for how these organics came together to form self-replicating systems. Verious tests have been done to see if the [RNA world hypothesis](_URL_1_) has support."
] | [
"Why do you think \"only a few species like sex\"?"
] |
How can a drug like fentanyl be multiple times stronger than something like morphine when they bind the the same mu receptors | [
"The difference in strength between morphine, heroin and fentanyl arises from differences in their chemical structures. The chemicals in both bind to the mu opioid receptor in the brain. But fentanyl gets there faster than morphine — the almost-instantaneous byproduct when the body breaks down heroin — because it more easily passes through the fat that is plentiful in the brain. Fentanyl also hugs the receptor so tightly that a tiny amount is enough to start the molecular chain of events that instigates opioids’ effects on the body."
] | [
"Depends on the country. Some countries have laws in place that ensure equal service for all providers using the same network, i.e. the network owner aren't allowed to diminish the service in any way for providers who \"rent\" their network. As for your particular example, they're both owned by the same corporation, so I would presume that their subscription plans (and pricing models) are targeted at different markets."
] |
Does the cliche "Don't talk, save your strength" have any actual merit to it? | [
"Talking demands particular breathing patterns. Physical exertion requires different ones. If you talk while trying to engage in physical activity you won't take in enough oxygen and you won't be able to do the activity as well. Furthermore, humans are terrible at multitasking. Talking distracts you from whatever else you're doing so you won't do it as well."
] | [
"Food takes time to reach the stomach, and you'll notice if you eat and then wait you'll be less hungry. Chewing more simply takes more time to do, and so you get full with less food"
] |
Aging slower when moving faster, like in space people age slower. | [
"They age at the same rate just not relative to us. If you where going 95% the speed of light then it would still take 1 year before your next birthday. However from someone that is going considerable slower you will be aging slower. by the time that your 1 year is up hundreds of years will have passed from their vantage point."
] | [
"The expansion of the universe is completely unrelated to the human perception of time. Perception of time is a very popular topic in many undergraduate and graduate university classes. The expansion of the universe is attributed to some unknown \"dark energy,\" whereas the human experience of time is just that: human. There are actually some good essays and discussions about other (E.T.) civilizations that could experience time backwards, that is, in their laws of physics, entropy would always tend to *decrease* with time, causality would be reversed, as well as many other interesting (and difficult to grasp) concepts. I will look for the book that I read about this in and edit this post if/when I find the title. It's actually quite an enjoyable read."
] |
Why are we not able to make artificial human blood for medical use, or why is it not feasible if we are? | [
"[Artificial blood is a thing](_URL_0_). As you can read on the wiki, the issue is that we don't have a good way of getting it to transport oxygen, which is obviously a pretty vital function of blood. Also, as you can read, clinical trials for that are on currently ongoing."
] | [
"Cost, at this time, it still requires an extreme amount of money/resources to launch something into orbit or beyond. There isn't anything that we need that badly that would justify mining an asteroid/etc."
] |
How did they encode images onto the Voyager golden records? | [
"[Wikipedia](_URL_0_) actually has a fairly easy explanation that you can try. An even explanation: Each image is made up of 512 lines. Each line can either be black or white (1 or 0). Then for color pictures they have three pictures, one each for red, blue and green."
] | [
"interesting.... this is from the front page of _URL_1_ today _URL_0_ it is the radio wave recordings of the recent sunspot release"
] |
After his assassination, was it ever considered to make John F. Kennedy a Saint? | [
"Beatification and canonization process requires the demonstration of miracles performed by the person being considered for sainthood. I don't believe Kennedy has any attributed to him."
] | [
"[Researchers say star in Hamlet may be supernova of 1572](_URL_2_) [Hamlet's Supernova: The 1572 Explosion in Cassiopeia](_URL_2_)"
] |
In medieval times, who/what would determine if you were an archer or a swordsmen in battle? Did the soldiers have a say? | [
"Being an archer required a fair bit of practice to develop the accuracy and muscle strength. Skeletons of English longbow archers are identifiable by larger left arms, bone spurs on left shoulder, wrist and right fingers. For most of medieval times, swords were expensive to own and thus a sign of wealth or nobility. Most likely only knights, squires and man-at-arms had their own swords. Foot soldiers most likely had a dagger and spear or other similar polearm. Conscripted peasants wouldn't be assigned to be an archer if they hadn't been previously trained. Untrained conscripts would most likely be issued a pole arm."
] | [
"Basically, in countries that have private ownership of land, land surveyors give their opinion on where property lines actually are on the earth. We research deeds, maps, etc. to determine where the lines are thought to be and then go to the property to find evidence of where the original survey marked it. The instrument on the tripod measures angles and usually distances, and without going into the mathematics, allows to relate all of the evidence to each other to see how it fits with the recorded descriptions of that property and the surrounding ones. The book is for writing all of the angles and distances in, and usually includes a sketch showing what evidence was found where. Once we see how the evidence fits together with the description, we give our opinion of where the property lines are, setting property corner monuments where missing and drawing up a plat or map showing what we found and set, and how we arrived at our opinion."
] |
I add flaxseed powder to things I bake. Does this actually add protein and omega-3s or is it denatured in the process of baking? | [
"Denaturation of protein is the point of cooking. You destroy the proteins of bacteria or parasites living in the food you're eating and begin breaking down the bio-polymers (proteins, DNA, starches, etc). The protein would be broken down during the course of digestion anyway. The omega-3s are lipids, so they shouldn't be broken down appreciably by the heat, as long as it's not burnt, and then they can do their thing when you eat them."
] | [
"When a speaker vibrates, it doesn't have to move in a single pattern. It can push out, pull back all the way, push forward a tiny bit, push back a little, push forward more, and so forth. When you consider the two frequencies of sound you mentioned, when they get added together- whether they were both played in front of you and you hear them together \"live\", or they were recorded separately and mixed with audio equipment, they produce one single \"wave\", but that wave is very complicated, containing the information of both signals. The speaker reproduces the same (or very similar, given that reproduction can never be identical) wave that you'd hear if you were physically present when the two tones were produced. It's your *brain* that does the work. It takes the complex waveform and essentially breaks apart the separate sounds that have been mashed together. What you \"hear\" isn't really what you *hear*, if that makes sense- your brain is doing a lot of work to let you hear multiple sounds."
] |
What makes materials transparent? | [
"All atoms and bonds have a vibrational frequency that corresponds to an specific energy level. If the incoming light has the same energy it can be absorbed by the electron in the atom or the electrons in a bond and move it to a higher energy level meaning the photon can not pass through making the object opaque. How the energy levels are set out in a material will determine if it is transparent or opaque. If there are a large number of electrons at the vibrational frequency that corresponds to the energy of visible light than it is opaque and if there are none/very few at these energy levels than the material is transparent."
] | [
"Not 100% sure but it sounds like your solution may have been too concentrated. Only a tiny fraction of the light was getting though. So not 0% transmittance, but 0.01% transmittance. When it's that low you are getting into the shot-noise limits of the electronics and it will return an error message rather than give you a false sense of accuracy. To solve this problem do a 1:10 dilution of your solution and then it should be in the range of your spectrophotometer."
] |
If you were to excerise why breathing oxygen from a can (95% oxygen for example) and worked as hard as possible, would you faint or die from removing the can/returning to normal air? | [
"Unfortunately, having **too much** oxygen is just as bad as having too little. While there are safe ways to hyper oxygenate and certainly some benefits in the short term, the side effects of doing so unsafely and unmonitored are too drastic for it to be a viable option. Oxygen toxicity occurs when the oxygen levels in your blood get too high, and side effects can include seizures, euphoria, severe vomiting, convulsions, confusion, syncope, or even passing out. You'll note that these are more-or-less the same symptoms as having too little oxygen in your blood. If we assume that your hypothetical scenario is safe, the person would likely just be short of breath for a slightly longer period than otherwise, as their body returns to normal oxygen levels and normal organ functionality."
] | [
"When you exercise you can control the rates of your heart. You can speed it up or slow it down through alternating between exercise and resting. With chemical stimulants you can't regulate your heart. Your heart is on, full speed, all the time. It gets worse with harsher chemicals than caffeine. Imagine redlining your car engine for extended period of time."
] |
How come alcohol triggers hunger even though its caloric itself? | [
"Am i the only one who looses their appetite after drinking ? I tend to not even want food until like 3 pm the next day"
] | [
"Anti-smoking commercials came about because of [a huge settlement with tobacco companies](_URL_0_). You see lots of commercials because they are funded by those companies. There hasn't been a similarly large class action suit against companies that make alcoholic drinks."
] |
Before Jefferson left for France in 1784, he was an outspoken abolitionist, calling slavery "a perpetual exercise of the most boisterous passions" After Jefferson's return from France in 1789, he withdrew his outspoken opposition to slavery. What caused this change in behavior? | [
"There's more to be said, but the great /u/freedmenspatrol has written a bunch of stuff about America's founding fathers and slavery, which often discusses Jefferson at length, including in these answers: * [Did Jefferson and Washington desire slavery to be eradicated?](_URL_3_) * [Were any of the founding fathers openly opposed to slavery?](_URL_0_) * [Why didn't all of the early Presidents own slaves?](_URL_2_) * [After the United States government adopted the ideal that all men have certain unalienable rights, how did we justify slavery and the atrocities committed against the Native Americans?](_URL_1_)"
] | [
"This is the whole \"paradox\" in the twin paradox. The resolution to be paradox is the fact that the motion of the twins is **not** symmetric. In order for the twins to meet up at the end of the experiment, at least one of them must accelerate, and therefore **change inertial frames** in order to turn around. In the standard formulation, the twin on Earth stays in the same (approximately) inertial frame the whole time. However the twin on the ship leaves in one inertial frame, turns around, and returns in a *different* inertial frame. Changing frames is not relative, there is no ambiguity in which twin accelerated in order to turn around. That's why the symmetry is broken."
] |
Why do people say eBay is so much worse than it used to be? | [
"Ebay used to be 90% individuals selling things. Now it's 90% companies selling cheap cellphone accessories made in china. It's impossible to get your own product promoted on the site because it'll get buried a sea of professional ebay merchants selling their stuff. Not sure if ebay has this option, but Armslist makes it so you can filter out businesses and ONLY see the individuals."
] | [
"The terms of service take the form of a contract. In terms of enforcement, it's no different to any other contract. If either side feels that the other side isn't sticking to the terms of the contract, there may be provision made in the contract for some penalty (if you don't do this we will add XXX dollars to your account; if you don't do something else we will close your account; etc). If a dispute arises, then either side can take the dispute to the court. Depending on which country you're in, there will be a different process for this. In the UK, for small amounts of cash, you can make an online application to the Small Claims Court, for example. Often when legal action begins, the other side decides it's not worth the cost of defending against that legal action - but if the case actually goes to court, a judge will look at the contract and the facts of the case, and will look at local laws to make sure the contract is itself legal, and will then order some kind of enforcement."
] |
How does our body absorb creams? Which parts of our skin do they go to? | [
"The main way that it works is that instead of liquid from your skin evaporating, the lotion evaporates instead. There are more factors involved, but they serve mostly as a barrier."
] | [
"There are a lot more steps involved than you see. From your perspective as a customer, you see the the money leave your account immediately when you make a purchase; but in reality there's a lot of processing that goes on and banks talking to each other and checking with each other before passing the money over. Just like how you don't get the money immediately when they do a refund, they don't get your money immediately when you make a purchase either."
] |
Questions on American history before Columbus. | [
"As /u/AlotofReading said, covering 20,000+ years of history over such a large area is impossible for single reddit post. It took me 6+ posts to give [a crash course in the history of the Ohio Valley](_URL_0_) through this lengthy time period. Since that questions is over a year old, feel free to ask any follow up questions you may have here."
] | [
"We didnt, we lived in warmer climates until we learned how slowly over time as we moved north"
] |
Have any of the people who disappeared under the Stalin regime ever been found? | [
"Lots of them. Groups like [memorial](_URL_0_) have been involved in locating and excavating mass graves all over the former USSR."
] | [
"Depends on the material and temperature. Sometimes the surface forms a reconstruction, as dreykevins explains. Other times the surface forms an oxide or some other surface layer, which can prevent recombination. Other times the pieces actually CAN be put back together, and this process is called \"cold welding\". _URL_0_ In ultra high vacuum, at low temperatures, the dangling bonds of most materials can remain unreconstructed for reasonably long periods of time. It's pretty common to study surfaces of materials by cleaving (breaking) a crystal under these conditions. I'm not sure what's happening physically in that case (or how to tell the difference) -- do the bonds truly remain dangling, or do they just form some sort of randomly disordered reconstruction?"
] |
Why do people say "my partner" instead of bf, gf, spouse? | [
"There are some situations in which \"partner\" may be the most appropriate word to use. Consider a person who is not married, but who has lived together with a man for 8 years, co-owns a house with him, makes joint financial decisions with him, and where they take each care of one another's health problems. To say \"he is my husband\" is incorrect since they are not married, but to call such a person a mere \"boyfriend\" implies a much less serious and permanent relationship than they have. \"Partner\" is more accurate than either of these."
] | [
"Basically, it's a lot easier to picture how far into a year you are when you break it into familiar chunks. It's a lot easier to comprehend being 7 months into a year than 212 days. Our minds don't handle big numbers well."
] |
Why does train speed limiting equipment cost $52k per mile of track? | [
"It isn't just the broadcast equipment for the limiter they have to pay for. Installing it could require modifying the track in some places, the system has to be tested/adjusted/calibrated to work properly, interference has to be traced and eliminated, etc. On top of equipment costs you've got to pay someone to do all the install and calibration work too."
] | [
"the theory was this. Pick a really, really, bad script that you know will bomb. Hire bad actors/directors/tech people. Do everything you can to make sure your production will fail. Fundraise a lot more money than you need to make the show. Let's say you need 500,000 to make the show, raise 1,000,000 instead. Embezzle the extra. Be creative about it, but take the bulk of the money for yourself. Show bombs, you tell the backers, \"sorry, we lost all the money, we'll do better next time.\" Enjoy your embezzled money knowing that the IRS won't bother looking at your books since the show didn't make any money. The accountant made a quip about being able to clear more money this way than doing an actually successful show."
] |
Quite a pointless question here, but it was on my mind: Why do Americans have mailboxes out the outskirts of their property rather than just a 'slot' in the door like we have in the UK? | [
"To save time in rural and suburban areas, so the postal workers can deliver mail without getting out of their cars or driving up the driveway. My mother-in-law had to give the post office a letter from her doctor saying she couldn't walk out to the street to get her mail before they would deliver it to her door. The postal worker wasn't lazy, he was under orders. In urban areas and some suburbs the postal service will deliver through door slots or in mailboxes next to the front door. It depends on where you live. This isn't really a history question, by the way, unless I misunderstand your question."
] | [
"Imagine a bathtub full of water, the water represents electricity. The bathtub has a faucet, which represents the generation of electricity. Imagine now that there are little holes in the bottom of the bathtub, all plugged up. When ever a home needs power, unplug the drain and let the water flow out. Now imagine that there are thousands of holes, all unplugged. The bathtub will drain very quickly - even if you turn the faucet on, full blast, only a few of the holes near the faucet will still get water flowing through, the rest of them will be dry until you plug up some of the holes again. It's generally the same concept with power."
] |
What’s the point of having a coil on the negative side of an aa battery? | [
"It's a spring that pushes the battery against the positive terminal. Without the spring, knocking the thing around could disconnect the battery. Imagine playing gameboy and every time you slightly move, the thing shuts off and turns back on"
] | [
"Cooking with electricity takes a huge amount of it. In a camping situation, there is not a source for a large amount of electricity. Carrying a highly volatile liquid, on the other hand, allows enough energy to power a stove to be carried even by a backpacker."
] |
Why is it when we get light-headed we start seeing spots or "stars"? | [
"a lack of bloodflow, so the optic nerve panics and starts firing blanks."
] | [
"As a former heavy smoker, i'm gonna say the THC as a hallucinogenic makes you feel 'unsure' of thoughts you experience, (how much, of what you think, is you or just the weed) and when you constantly subject yourself to that tedious way of thinking, you get used to questioning reality while being unsure of what is real and what is an illusion. you don't put trust in anything as a rule. ie. illuminati, aliens, and general conspiracies."
] |
how exactly does the body turn calories into fat? | [
"Calories are units of energy, so what it actually means is that they convert high energy containing biomolecules into fat. The process is complex, and would likely sound incomprehensible to most people (it did to me for a long time), but in broad strokes the the molecules are chemically altered and added to fat, if there are more of them then your body can quickly break down to provide itself energy. High energy containing foods (high calorie foods) are more likely to saturate the energy requirement of your body, which then causes it to switch over to fat synthesis at increased rates."
] | [
"Because the problem with sunlight is not the heat, but the exposure to UV radiation, which damages skin cells and their DNA, leading to sunburn in the short term, and to melanoma and other problems in the long term. Melanin, the pigment responsible for the darkening of the skin, is placed above the DNA of skin cells, protecting it by converting the energy of UV rays - energy that would damage the DNA - into heat. So yes, a little more heat is produced, but that's easily dissipated and won't cause any problem."
] |
What did the Axis refer to the Allies as in World War II? | [
"There's a whole range of expressions even in Hitler's speeches. He often used simply *unsere Feinde* or *die Gegner* (\"our enemies\" or \"the opponents\"). Of course, when he got polemic, he started referring to the Allies as the \"international plutocrat plot\" or the \"world jewry and its democratic helpers' helpers\" - and later as \"the jewish alliance between capitalism and bolshevism\" once Russia joined the allies."
] | [
"Anna Komnena called Bohemond a Gaul several times in *the Alexiad*. I have to think the term is pejorative. However, I only read the English translation, never the Greek so there's always the possibility of translator bias or nuance. That said - the *Alexiad* is an interesting source from the viewpoint of the daughter of the Emperor of Byzantium. Then there's *The Chronicles of the Crusades* by Joinville and Villehardoin. That one is still on the shelf."
] |
Does anyone have any recommendations for books on the KGB? I am especially interested in the period during the fall of the USSR. | [
"The fall of the Soviet Union was covered in relative detail by Serhii Plokhii in ‘The Last Empire: The Final Days of the Soviet Union’(2014). He covers the drama of the final days of the country with detail on the KGB, including Putin, when necessary."
] | [
"Though the production values are vastly different, I enjoyed the PBS series 'I Claudius' after watching Rome. There's some continuity between the series. Rome dramatizes Augustus' rise to power, Claudius begins in the waning years of his reign."
] |
Is there a limit to how fast a mobile phone can move before it can’t keep a signal? | [
"Yes, there is a limit. For a cellphone to operate, it must be in communication with one or more cellular signal towers, each of which covers a certain area. If the phone is traveling too fast, it will not have time to send data to/from the cell tower before it is already out of range. Granted, this would have to be at a very fast speed: something like a jet."
] | [
"only if it's structure is perfectly non-[amorphous](_URL_0_) so that it wouldn't start contorting with the inertial effect commonly known as the [centrifugal force](_URL_1_). This would rule out glass and many plastics Also it would have to also be in a perfect vacuum so that air resistance, or friction with the air, wouldn't slow it down. Both a perfect vacuum and a frictionless surface are practically impossible and have never been achieved, so this is borderline-hypothetical to begin with."
] |
How effective is calcium in toothpaste (Calcium Carbonate or Dicalcium Phosphate Dihydrate) in preventing cavities or strengthening the tooth enamel? | [
"Calcium carbonate is chemically inert in saliva. It is most likely used as a mild abrasive. Dicalcium phosphate is also used in many toothpaste formulations as an abrasive: although largely insoluble in water, it may re-mineralize the teeth surface (which is basically hydroxylapatite - a complex calcium phosphate). [A study suggesting some kind of activity](_URL_0_) [Another study that did not find any difference between chewing gum with or without calcium phosphates](_URL_1_)"
] | [
"One of my personal favorite castles is the Crusader fortress of [Krak de Chevaliers](_URL_14_). It was never taken by force, was eventually only captured by treachery. It is an excellent example of the medieval European use of castle construction to defend and consolidate contested territory. Some interesting defensive devices include: * The gate to the keep not being in line with the gate to the curtain wall, meaning you had to walk under the walls with crap being thrown and shot at you to get there. * Barrel vaulting, making the fortifications themselves incredibly strong. In the recent civil war, Krak de Chevaliers seems to have survived rocket and artillery attacks relatively unscathed. * Position: the castle is constructed on a steep hilltop, and the gate is built significantly above ground level, accessible only by a ramp * Broad lower walls, making sapping attempts relatively pointless."
] |
Why and how the Twinkie factory shut down and reopened. | [
"The company that made twinkies went out of business, basically due to poor management. In its final days, the workers went on strike because they were unhappy with how the company was being run and how they were being treated, and that was the final straw that killed the company. But it was probably just a matter of time either way. When companies fold, any assets they have are generally sold off to the highest bidder. This includes the rights to product lines. Another company thought they could make money selling twinkies, so they bought the product name/recipe/etc. I'm not sure if they bought any of the left over equipment and/or actual production factory, or whether they just started making twinkies in their own facilities."
] | [
"This is really going to come off as anti-wind-lobbyist-crankery, but I'm asking this in earnest. What ramifications if any are there to the weather if one places a huge wind farm somewhere? Thermodynamics says that although the wind is \"renewable\" it's not like the turbines produce \"free\" energy, they take the wind energy and convert it to electricity, the end result of which is the wind gets slowed down, right? Have there been any decent studies on this, or is it all crank stuff?"
] |
Why is the oil and gas industry going under? | [
"Because I spent two years getting my cdl and working on a oil platform at slave wages to learn the trade. Got a job making 70k on another rig in sd, the price dropped, everyone was let go and the industry basically collapsed. If anyone wants another industry to fail drop me a line and I will spend another two years training for it."
] | [
"Was Oliver North really just a scapegoat for the big fishes?"
] |
Where do governments get all this extra money? | [
"Appropriations and deficit spending. Governments rarely if ever operate using cash. Everything is done using credit because that's the only way for a large entity such as a government to stay liquid. So they borrow money to run the government from various sources, then they pay the interest on those loans. Remember the USA government threatening to default lately on those debt ceiling increases? Those are the interest payments to the loans taken out to pay for things like the 3.7 billion dollars pledged. Whether the government had a pool of 3.7 billion sitting around waiting to be appropriated or if they're increasing agency funding they first do so using credit. Then if taxes don't meet those commitments then its deficit spending. Either way everything comes through credit first"
] | [
"For the most part, we don't. Criminal tax evasion requires intent. This usually occurs when there is some other crime involved, and the income from that crime is intentionally hidden (like Al Capone). It also sometimes occurs when the person is a serial tax evader, and intentionally hides income (like Wesley Snipes). Usually, unpaid taxes are enforced civilliy, meaning garnishment and seizures."
] |
What is "being triggered" by something? When should I be worried about triggering people? | [
"Basically it pulls repressed memories. If someone was a rape victim, talk about rape or anything close to the subject would \"trigger\" them. The alarming amount of bull people claim triggers them and want discussion to cease has grown absurd though."
] | [
"Tumblr is a blogging platform. It's typically best for short-form post. Think of it as an in between Twitter and a traditional blog. Tumblr essentially allows you to post text, photos, videos, etc. It also makes it very easy to share content between blogs. For instance if you like a particular photo you can \"reblog\" the post, with credit, to your blog. The entire process is pretty easy to get a hang of if you are just starting out yet still offers the ability to professionally blog easily. Tumblr became popular with youth and this popularity gradually led the platform to be adopted by journalists, artists, and other companies as a way to spread their content easily."
] |
How massive restaurants and food makers can still have "secret" recipes | [
"The secret parts of the recipe are the methods of preparation, and the amounts of each individual ingredient. All they have to declare for USDA regulations are the relative amounts of each ingredient, and certain things (\"natural flavors\") don't have to be directly specified. As far as keeping it secret inside the company, batches of combined ingredients are prepared separately from each other. Nobody on the production line knows the entire formula."
] | [
"Fair warning, I sell IP for a living. Basically, we are very careful what we share when we are selling. We show just enough to let you see the potential, but not enough that you are able to duplicate the work without us. Sure, you may see a piece of it, but its a long road between one website page and a fully functional site."
] |
Why do we assume life must follow the same rules as on earth when looking for extraterrestrial life? | [
"Scientist don't assume all life must follow the same rules. It's just that the life on Earth is the only kind of life we know of, and we know it very well, so it's the starting point for looking for extraterrestrial life. The conditions of earth *are proven* to nurture life, whereas other forms of life are purely *hypothetical and speculative*, there is no proof of other kind of life existing, so we focus to search the kind of life which is proven to be possible."
] | [
"Well depending on how many fingers they had they'd probably use a different base counting system. We use base 10, there are 10 different units before we gave to move to another digit. This is largely from the fact we have 10 fingers to count on. So a 8 fingered alien would count 0 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 20. But the numbers are still the same and you can easily convert. But otherwise maths is pretty much universal. The square of two sides of a triangle always will equal the square of the long side no matter how you count."
] |
Why aren’t plants black? | [
"The most intense light is in the red orange part of the spectrum, look at the solar spectrum. Since a plant isn't likely to expend energy to produce a whole range of different molecules for energy production it is more expedient to use one that absorbs what the sun is putting out more of, I.e. red ight. Every energy pathway involves dozens to hundreds of enzymes so having blue absorbers and green and violet etc would overload the plant. not to mention that nature just might not have provided those molecules to begin with."
] | [
"Your eyes would have evolved differently to perceive the light in a way that was advantageous for survival. Chlorophyll is a pigment well-suited for our sun's spectrum (and the wavelengths that penetrate the atmosphere), but another pigment may be better suited for a star that gives off a different spectrum."
] |
Why is 24 fps still being used when 60fps is a thing. | [
"People tend to favor 24 fps when it comes to movies. The lack of motion blur on higher fps tends to give the film a cheesy soap opera feeling. It should also be noted that quite a lot of movies will have some scenes shot in higher fps if they want that scene to show more detail. For example, incredibly fast paced highly choreographed fight scenes will usually not be shot at a standard 24 fps."
] | [
"My guess? When you're dealing with a lot of makeup, prosthesis, special effects its easier to hide flaws. You can see acne under makeup in high def, you couldn't really see that back in the day. Just a guess."
] |
Why is static black and white and not colour? | [
"Analog TVs had a circuit called the [\"color killer\"](_URL_0_). It was designed to eliminate any color from the screen when B+W programming was being received. The B+W signal did not have a [color burst](_URL_1_) reference signal, and it is the absence of this color burst which triggers the color killer. Static means no signal and no color burst."
] | [
"Electricity has to complete a circuit - i.e. it has to go into them, and then back out. Think of a battery - they have two poles, one for the current to flow out of, and another for it to return. If something is sitting on just one wire, it's not completing that circuit, and the electricity has nowhere to go."
] |
What is better, holding back a sneeze or letting it out and why? | [
"I'd say letting it out. sneezing is triggered by something irritating your body and wanting to get rid of it, generally a foreign body or pathogen build up."
] | [
"Your whole high school is in the gym for an assembly. The presentation comes to an end and everyone needs to leave all at once. If you never open the doors, people will never leave. If you open one door, how long will it take for everyone to leave? If you open all the doors, how long will it take for everyone to leave? Relate this to your problem. Basically, it doesn't matter how fast or slow you open the bottle, the air will equalize anyway. It's only a function of how fast it equalizes."
] |
How does an autopilot work? | [
"Autopilots are based on a [negative feedback loop](_URL_0_). A motor moves a control surface, until that control surface has the desired effect. When the control surface has had the desired effect, it is not moved any further. As for what is the \"desired effect\", the most common scenario is to use a flight director. The flight director can be programmed into a number of modes - horizontally, you can set it to fly a particular heading, or to follow a particular navigation aid, and vertically you can set it to climb or descend at a particular airspeed, a particular vertical speed, level off at a particular height, or follow a landing system to the ground. The flight director works out how high or low the nose should be, and how much bank angle to use. And the autopilot does whatever the flight director tells it to do."
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s): You can find the basic answer with a google / wiki search. Please start there and come back with a more specific question. If you disagree with this decision, please send a [message to the moderators.](_URL_3_)"
] |
By what mechanism is silver (and other heavy metals supposedly) antimicrobial? | [
"It is called oligodynamic effect ([wiki](_URL_0_)) and the exact mechanism is not completely understood AFAIK, but these metals are wide ranged catalysts, meaning they could easily push an otherwise stable protein over the treshold of some reaction that would denature it. This is most likely the effect."
] | [
"It is so high in sugar that organisms don't have enough moisture to live. The sugar is hydrophilic and will suck the water out of bacteria that encounter it. Basically the same idea behind salting meat, except that uses salt of course."
] |
[electronics] What's the difference between an op-amp and a transistor? | [
"An op amp is built out of transistors. You can make lots of different varieties of circuits which do amplification, and an op amp is just one useful type that we use a lot. The innards of an op amp look like [this](_URL_0_). Each of those circle thingies with the arrow inside labeled by a Q is a transistor."
] | [
"Ask Reddit is for personal opinions, stories, and the like. Essentially subjective answers to questions without hard answers. Something like \"whats your favorite food\" is a good post there ELI5 is for getting a simplified answer or explanation to a question that you don't understand. A good thread here would someone explaining in easy to understand terms how a car engine works."
] |
Were there any civilisations or societies that developed through fishing/aquaculture? | [
"Absolutely! Many coastal and many riverine communities developed based on water resources. Plateau and Northern California tribes didn't have land-based agriculture but based much of their diet on salmon runs. But far more ancient are the ancient Peruvians on the Pacific coast ([Scroll down to \"Coastal Beginnings\"](_URL_0_)). The early time period was known as \"Cotton Pre-Ceramic.\" Because of the plentiful fishing and hunting of sea mammals, societies developed the earliest cities in the Americas. They began agriculture with cotton farming, which produced clothing but also fishing nets. [Aspero](_URL_1_) is one of these earliest cities, dating back to 3000 BCE. It's believed that initially agricultural foodstuffs wasn't grown on the coasts, but traded with inland communities."
] | [
"This question is getting a lot of traffic after being [tweeted by @reddit](_URL_5_), so I thought I'd welcome those of you that haven't visited /r/AskHistorians before to the subreddit. Please do bear in mind that in order to keep the quality of answers here high we have [strict rules on comments](/r/AskHistorians/wiki/rules) that are actively enforced by the moderators. We don't want to stifle discussion, but remember that: * Answers must be informed, detailed and backed up by historical sources. This applies to **all** top level comments (direct replies to the original post) as well as responses to follow-up questions. * All other comments must be on-topic and historical, i.e. the current olympics and political discussions about the pros and cons of socialism are both off-limits and will be deleted. Otherwise, feel free to add answers, expand on existing answers or ask follow-up questions, and we hope you'll stick around!"
] |
Will it ever be possible for humans to recreate extinct animals? | [
"Yes its possible. And its been done once already with the [Pyrenean ibex](_URL_0_). Sadly, the ibex was born with a lung defect and died 7 minutes later. Thus, becoming possibly the only animal to truly go extinct *twice*."
] | [
"There are emulators out there, as well as emulators for early PC games. I'm not sure why you think there aren't. The reason the original companies don't make the games again is that it doesn't make much money. So you have to rely on community programmers instead."
] |
What is the purpose of having academically gifted children attend university at an early age? | [
"Skipping grades and attending college courses can be one of the simplest ways for gifted children to learn material that matches their abilities. However, it's not without problems - mostly the social ones which you mention (_URL_0_). Probably having them attend special classes or schools with other gifted children their age would be better, but it's harder to do that. As to the long term benefits, it's hard to say for sure, although in child prodigies grow up to be relatively normal adults."
] | [
"There was an segment on NPR about this yesterday. The host asked the same question you did. The short version is that it's painful, expensive, and even if they get cervical cancer it's not the end of the world. Cervical cancer (according to the speaker) is slow growing and the chance of it actually causing problems is very low. As you point out, false positives are a problem, since they're expensive. Also, women under 21 get cervical cancer so rarely it's a waste of time. It's like asking why men under 50 don't get prostate exams. **TL;DR** Painful, expensive, unnecessary tests should not be run for the sake of running tests."
] |
exactly how, by what mechanism, does an air bubble in your bloodstream actually cause death? | [
"Small bubbles can block capillaries in vital organs, most urgently the brain, causing anything from pain and inflammation to neurological damage and paralysis. A small bubble impedes blood flow the same way a solid obstruction would — the bubble's surface tension relative to its size is too great for the force of blood to break it up or shove it along. Bad? Yes. Fatal? Probably not, although see below. A big bubble, on the other hand, gets us into the vapor lock scenario. Your heart, like the fuel pump in an old car (cars with modern fuel injection work differently), is a simple mechanical device. In ordinary operation, its contracting chambers squeeze the blood out and force it through the circulatory system. All is well. Now imagine a massive air embolus shows up and your heart starts squeezing on that. There's nothing to get any purchase on; the air just compresses. Blood flow stops, and eventually so does your heart. [Sauce](_URL_0_)"
] | [
"Related question - Why is it safe to swim in chlorinated water, whereas inhaling chlorine gas will kill you?"
] |
How can a device such as a phone 'resist' being charged if it plugged in and connected to power? | [
"The device has a relay switch that can be toggled to allow or deny the charging cable from delivering power. There is also a low power circuit that can ‘test’ the cable to determine its function (in the case of iPhones the lightning port can be either headphones, a connection to a computer or only a charger) if the test circuit does not like what it hears back from the cable it will keep the relay open and it will not charge the device."
] | [
"Touch screens sense the [capacitance](_URL_1_) of your fingers, which is a related but different concept from conductivity. Implementations do of course vary, but the basic idea is that you have a grid of sensors which continually measure the capacitance of a local region; when you touch the screen, you change the local capacitance for some of the sensors, which is converted into a logical \"tap\". A [Theremin](_URL_0_), a musical instrument you can play without touching it, operates on a similar principle. (Depending on the calibration of the touch screen, it can sometimes register a touch when your finger is very close but not touching the screen.) Putting on a glass screen protector doesn't significantly change the capacitance near the screen, so as long as it is sufficiently thin, a touch will still register."
] |
what is Bose-Einstein condensation and how does it work? | [
"You are aware what a solid is, and a liquid, and a gas and a plasma. A Bose-Einstein condinsate is another state of matter, In a solid, the atoms are in a strong structure (or lattice), if a BEC after cooling the matter down to a tiny tiny fraction of a degree above absolute zero and the atoms all appear to occupy the same place, they loose there individual atom position and all collapse into a single blob. If you don't mind being patronized, this website is very helpful _URL_0_"
] | [
"[Richard Feynman](_URL_1_) ELI5's it pretty well in about 2 mins. Alan Alda had a contest and this [8 min video](_URL_0_) won."
] |
Why do meal-in-a-box (like Hamburger Helper) recipes require hot water when you are just going to boil all of the ingredients anyway? | [
"Those meal in a box meals contain a mixture of cooked and dehydrated, raw and dehydrated, and dry ingredients. You add water to rehydrate the stuff that needs making back into food, to activate the stuff that's there to stick *that* stuff together. Then you bake it to cook the raw stuff, and activate the binders, leaving behind something that's got something claiming to be texture. Dry TVP has a water content of about 3% or less. You rehydrate it to ~60%, at which point it's technically edible but has the flavor and texture of wet cardboard. You mix in the \"Mexican non union alternative to beef and tomato flavoring\", then bake it down to ~40% water, at which point it has a mouth feel exactly unlike beef Bolognese. Also, adding hot water to the mix should activate the binding agent, either starch or egg protein, before the dry ingredients have had a chance to start absorbing water. Adding cold water will have the exact same ultimate effect, but things will be more mixed, and have an odd texture."
] | [
"It could be a case where the label is printed well before the product actually gets canned/boxed, so you cant put a date on the label as you don't know when it will actually be put on a product. So it directs you to where the date will be put during the final canning/boxing process."
] |
Why are there sometimes blank power outlets? | [
"Usually if it's right next to an existing 120v receptacle, it's a phone or network line. In commercial settings the wire will be ran for the 120v receptacles while the walls are open (no drywall). During this time a string will be installed from the opening to the open office ceiling above for the phone/network outlet. This is so that a communications contractor can come in after drywall/paint and fish his phone/network line using the string. If he doesn't show up for a while or never, a blank plate is put on. Unscrew that blank plate and most likely you'll see a plastic plate with no wires. There will probably be a pull string waiting to be used, it goes up to the suspended ceiling above you."
] | [
"Welder/Boilermaker here, It should say right on the front panel. AC, DC, or AC/DC. There's also a stamped tag on the back of most welding machines that gives you all the specifics for that machine."
] |
Who created the group "Anonymous", and what is their purpose? | [
"Anonymous sprang up on 4chan, where every poster is anonymous. As far as I'm aware, while there may be a core group of people that communicate via an IRC channel, or something, they're not really a set group of people with defined goals. Pretty much anyone can claim to be from Anonymous, or to speak for Anonymous. The whole \"We are anonymous. We do not forgive. We do not forget\" thing was a memetic joke on the /b/ board years before \"Anonymous\" started to make themselves known as a group - it was quoted mostly whenever a group of /b/ users decided to raid another website or send 1000 pizzas to someone's house, or whatever. This was back when 4chan (and /b/ specifically) called itself the \"internet hate machine.\""
] | [
"Imagine a bully at school. It's the same one each day, taking the lunch money of the same handful of kids. You take note that kids seem bullied, and it's very easy to identify who the bully is, after all you only have to talk to a handful of kids to get something of note, plus everyone is pointing the same direction. You do something about it. Now you shut down KickAssTorrents. But imagine that you have a school, a very very large school, and there's *hundreds* of bullies. They're all called Marc. So every time you get someone to tell you who bullies them, it's 'Marc'. They also all look very similar, so you never know who did it today. You never know who is actually to blame. Worse yet, some of these Marcs live in other states, and due to bureaucracy you can't even get a hold of their parents! And every time you finally shut someone down, a new Marc transfers over to your school! :o That... is basically Pirate Bay."
] |
Does the "randomness" of quantum mechanics translate to macroscopic events? | [
"> In all macroscopic situations, it seems like any event that has a probability of occurring in one of multiple ways can really be predicted if you take more detailed and relevant measurements. If you're prepared to take microscopic nondeterminism on trust, then it's easy to see that we have some macroscopic nondeterminism as well, because there exists equipment can that amplify microscopic events up to things we can detect with our senses. (E.g. Geiger counter.)"
] | [
"_URL_0_ Basically, given an infinite universe and infinite time (and assuming that matter/energy/etc. doesn't fundamentally break down and irreparably change over time), then you would expect that any given finite situation would reoccur within a long enough time frame. The amount of time involved for anything of significant size is insanely large though. Many gazillions of times the age of our universe."
] |
Why didn't Asian cultures discover North America before Europeans given the two land masses are only about 55 miles apart at the Bering Strait? | [
"Of course there's room for new answers and there might be new discoveries. But there's also an FAQ entry and some other answers you can find by searching \"Bering\" in the sub. FAQ: _URL_0_ by u/Reedstilt Another thread I think had a good answer: _URL_1_ by u/The_Alaskan"
] | [
"Most people copy ideas. If the tribe A comes up with a good idea, then tribe B next door will copy it. Or tribe A's good idea may make it powerful enough to conquer tribe B and force them to adopt their idea. Isolated communities may not be exposed to outsiders' ideas (like modern technology) so they don't copy them like most other groups. Secondly, some areas aren't well-suited to a modern lifestyle. Some areas aren't suitable for agriculture (like the Arctic) so hunting and gathering is the most viable way to survive."
] |
A bill was passed to remove Internet privacy regulations today , what does that mean really ? | [
"Basically, now American ISPs can sell the data they collect from you to advertisers without your permission."
] | [
"\"America\" can't, but Texans in his district certainly can. Once every two years they get the opportunity Mr. Smith is a congressman, and he represents one particular place. Only people from that place get to vote for or against him. Unfortunately Mr. Smith represents a wealthy area near Austin, Texas where I suspect wealthy people in the music industry reside. SOPA, and PCIP both greatly benefit the recording industry over the consumer. Sounds to me like he's representing his constituents well. If you don't like it (I know I don't) vote for a congressional representative in your area that prioritizes consumers over industry."
] |
What’s the physical differences between 3G, 4G and 5G networks? | [
"1G, 2G, 3G, 4G, and 5G refer to generations of cellular technology marked by improvements that are incompatible with previous generations (except 5G which will be supplementary to 4G and hopefully alleviate 4G congestion). How the performance is delivered goes beyond improvements to a single physical device; it's a set of technologies that include encoding, physical antennas, which radio bands they broadcast over, the strategy employed in arranging antennas such as how many per tower (cell site), how many towers, and how close together the towers are placed."
] | [
"Same technology, but Verizon likes making lots of money. They could offer much better plans, but as they are usually already the best option for their customers, so they don't need to. It does help that Google Fiber is in select densly populated areas, allowing for less infrastructure. $70/mo for 1Gbps up and down is a little overkill though. I have FiOS and pay $75/mo for 75Mbps up and down, I would love to pay $50/mo for 100 Mbps up and down."
] |
Why hasn't Guantanamo been closed yet? | [
"Congress has prevented it. The President isn't the only one who has say in the matter."
] | [
"Usually with sites like Wikileaks or say the more often target Piratebay the servers are not in the US or other friendly nation so they cant just walk in and flip the switch. If they can manage to remove the site they often have mirrors and other servers ready to spin up and put it back online elswhere."
] |
Throughout history, Anglophones thought left-handedness as a curse of God as it went against the proper left-to-right system of writing. Is there any records of how Arabs or Hebrews viewed left-handed people with their right-to-left system of writing? | [
"Generally speaking people in the arab world considers the right hand to be the dominant and proper hand despite the writing system. This is reflected in muslim scripture. For example the hadith states that ablution should begin with the right hand and th right side of the body and then continue to the left, affirming the right side as more pure. \"What your right hand possesses\" is used as a euphemism for slaves in some places in the hadith, suggesting that the right hand is dominant, commanding. As for how left handed people were treated İ can't comment directly. Do you have a source though that right hand favoritism is at all related to writing direction?"
] | [
"Typically someone who is strabismic (crossed eyed) sees double early in life but the brain and visual system are incredible. They will do whatever needs to be done to insure that you see to the best of your ability. It does this in several ways. One way is suppression- your brain will only receive information from one eye at a time or alternate which eye it receives messages from. Another way people with visual problems adapt to see better is by changing their physical mannerisms. They may tilt or turn their head to point their eye or eyes at whatever it is they want to see. Typically strabismic patients do not have depth perception which may prevent them from doing certain jobs but very rarely is it classified as a disability. Source: I know a vision therapist that works with patients who have strabismus."
] |
Why do we appreciate events more after they are finished? | [
"The best thing I can liken this to is giving birth. Anytime you ask a mom about giving birth, they'll usually tell you horror stories, but they'll be smiling the whole time. A few months later they're usually willing to go through the whole process again, and do so eagerly. This is because of endorphins. Whenever your body goes through a stressful event, good or bad, it starts dumping a cocktail of chemicals into your bloodstream. Those endorphins create a sort of pleasure response to the memory that's being made. While mothers will often think of the pain caused by giving birth, their brain remembers the flood of endorphins and causes it to be a good memory. While sitting in a crowded concert hall, being crushed by smelly drunks, and only half hearing a mediocre band playing, may be a miserable experience; you'll look back on it and your brain will remember the feel good chemicals caused by a stressful night out."
] | [
"Post-coital tristesse is the term you are looking for! Do a google search and surf around, there are several perspectives, but the most fascinating to me is that the Greeks characterized this phenomenon and discussed it. Aka I don’t have a simple hard and fast answer for you, but that’s the name."
] |
Red Shift and Blue Shift | [
"Look at [this picture](_URL_0_) Imagine the black dot is a star that is moving down the screen. The light in front of the star is squashed together making the wavelength (the distance between two waves) shorter, this makes the light bluer. The light behind the star is being stretched making the wavelengths longer, making the light redder. This is seen in far away galaxies (which are all moving away from us) where the light coming from them is shifted towards red. Its hard to observe blue shift with light but it can be shown using sound. As a car approaches you, it sounds higher than when it is moving away, this is the same principal but with a different wave. [I used this to make the picture if anyone wants to play around with it.](_URL_1_) Also this doesn't seem simple enough for a five year old so if anyone can explain it in simpler terms that would be great."
] | [
"SuperK is underground to shield it from ambient and cosmic backgrounds. The LHC is underground to shield to the local environment from it. Even if the amount of synchrotron radiation is much less than LEP, you still have other losses from collimators and collisions."
] |
How does refrigeration and air conditioning work? Because in order to make something cold you need something colder. | [
"Heat flows from areas of high concentration to areas of low concentration. But since heat is a property of things you can create areas of high and low concentration by causing areas of high and low concentration of *those things*. So if you take a gas and compress it the temperature goes up because you are concentrating the heat in that gas. This then means heat flows out of the gas into the surroundings, and if you later allow the gas to expand it is now cold in comparison to the surroundings. More heat flows in, you compress it to dump heat again, repeat this cycle. The key then is to change the location where you are compressing and allowing the gas to expand, such that you are expanding inside an insulated container to soak up heat from it and compressing outside it to dump heat into the outside world. What you end up with is a heat pump that moves heat from inside the container to outside, cooling it down. This is the basic idea behind refrigerators and air conditioning."
] | [
"Games would run better running on the hardware they were designed for. Suppose that you're working with Bob, your best friend. You know each other so well that when you raise a thumbs up, Bob will fetch a coffee for you, and whenever you scream \"OH GOD NO\" Bob will immediately fetch a bug spray because you just spotted a cockroach, specifically a cockroach. If someone were to suddenly fill in for Bob, they'll have to ask you constantly why you're raising your thumbs and why you're screaming specifically that phrase. You can tell the new guy to fetch a coffee everytime you raise your thumbs, but they'll never know the real reason why. Nobody can really replace Bob, how he thinks, his workflow, and so on and so forth. If you find someone that does exactly what Bob does the exact same way Bob would do it, then you just found Bob, not someone else. That's how emulators work"
] |
How to companies that advertise products and services with a no questions asked money back type of guarantee keep themselves from getting taken advantage of? | [
"they can't. people will take advatnage of it, like what happened in costco. they had a policy you could return any item within 3 years, and people bought electronics, waited 3 years, and returned them. it made costco change their policy. but on average people as a whole won't be dicks like that. if it becomes a problem, the company will change the policy."
] | [
"They don't really. The chance of that stuff actually happening to you is practically nil - but if it does, from a legal standpoint you were warned in advance. From a medical perspective they probably have ways to tell that a certain mixture *could* have some side effect without needing actual cases of the effect occurring, and reason that the odds are so low it doesn't justify modifying the formula."
] |
Can someone explain to me the difference between finding the derivative of a function, and finding the tangent line? | [
"A derivative of a function is a constant evaluation of the rate of change of that function. The tangent line is the rate of change of that function at *one particular point*. If you evaluate the tangent lines at all possible points of the function, you get the derivative. Another way to say it is, if you get the derivative of a function, and you plug in a particular value for *y*, you get the tangent line at that point."
] | [
"while frying you are almost always adding oils/fats to food while grilling you are generally removing fats, since the fat will be liquified, drip off the food then burn when it hits the bottom of the barbecue creating that smokey flavor."
] |
Why is it that digital storage sizes are powers of 8? | [
"Hard drive manufacturers do not use the binary definition of a megabyte. Instead they use the decimal definition. so in binary a megabyte = 1024000 bytes a megabyte in decimal = 1000000 bytes Why? Marketing. This is why when you buy a 1TB hard drive from western digital when you install it in your computer its only 931GB. The decimal system definition allows them to advertise larger sizes."
] | [
"Imagine you want to cook some food. You reach for a recipe book. Not being very brave you go for something simple. You take the eggs and mushrooms and butter and ham out of the fridge, and you follow the instructions carefully. At the end of the process you enjoy your omelette and think \"if I ever want this omelette again, I'll go back to that recipe\". Files on your computer are recipes for software to use to do things: show images on your screen, play music out of your speakers, show video and play the soundtrack, help your spreadsheet software fill in some data, and so on. Each file format is a recipe originally intended for a piece of software to persist data between program executions, and some file formats became \"open\" in a certain sense and useable by many pieces of software - e.g. JPEG, MP3 and so on - and some file formats are specifically designed to ensure interoperability (e.g. OpenDoc format)."
] |
Are there any fusion reactions using plain hydrogen? | [
"Sure, you can fuse anything with anything. Although only certain fusion reactions are exothermic, and only certain exothermic fusion reactions actually release a decent amount of energy. DD and DT are ideal for power generation."
] | [
"I'd be simpler just to build a [fusor](_URL_1_) with deuterium. _URL_0_"
] |
Why are bugs so creepy to us? Genetics or something we learn? | [
"It's definitely a social construct. Why it exists is hard to say but insects have killed ore than 50 percent of all humans (malaria) so it make sense to be afraid of such things."
] | [
"Think of a marbel in a field at night, you know it is somewhere on the field but you just cannot make it out. Now imagine it's moving. On the other hand, imagine a street light with a fly buzzing around it. You cannot see the fly but if you look at the light long enough you can just make out something changing in the light on a regular basis, a slight flickering where the light is usually steady."
] |
Is the shape and general make-up of sperm identical, or at least similar, amongst all sperm producing animals? | [
"Oh man, not even! For example, some species of fruit fly have sperm tat are multiple times longer than the fly itself. Some species have heterogeneous populations, some being incapable of fertilization but serving as 'blockers', some even being hunter killer sperm! Check out Sperm Wars. It's a rad book."
] | [
"Imagine a flamethrower and a crowd of X-Men kids. there's a range of powers. Burn the crowd for 20 seconds and they all die. Burn them for 10 seconds, and maybe that thick skinned or overly hydrated kid survives. He wouldn't have survived the assault for 20 seconds, they would all have died. But now he survived. X-Men kids reproduce via masturbation, and X-Men will be X-Men. Soon you have a crowd of X-Men kids who are again all varied, but all have the hydrated skin or thick skin. The chances of one of them having both, or other fire resistant powers is now quite high. You flamethrower again, 10 seconds, now most of them are alive. Keep going to 20 and..... Some are alive. Some have multiple defenses, they're fireproof..... They start wanking.... Oh no......."
] |
If the universe is 14 billion years old and the sun is 4.5 billion years old. Was the universe 9.5 billion years old when the sun was born? | [
"Yes, that's right. (Your numbers are a little bit off the standard ones, but close enough for discussing the idea!) If you want to get into relativity factors... those ages are the ones for observers at rest with respect to the cosmic microwave background (or the bulk of the matter, on average). Observers that are traveling at high speeds relative to that frame will see shorter times for both of those ages, due to time dilation."
] | [
"Not a biologist, just someone who overhead a conversation with a veterinarian once. She said that the \"dog years\" scale of multiplying by 7 isn't very accurate for a couple of reasons. One is that different breeds have different life expectancy. Some breeds tend to live only seven or eight years, and some typically live fifteen or sixteen years. Additionally dogs tend to achieve sexual maturity faster than humans relative to life expectancy. Humans tend to hit puberty at about the 20% mark of their lifespan (around age 15 for a life of 75 years), but dogs can hit puberty as early as six months of age, which would be the 5% point of a ten-year lifespan. So comparing a one-year old dog to a seven-year-old human isn't particularly accurate in terms of their development."
] |
In the years before the American revolutionary war, Britain seemed bent on containing American settlers' expansion westward. What were their motives? Wouldn't expansion benefit the empire? | [
"> King George III issued the Royal Proclamation of 1763 on October 7, 1763, which outlined the division and administration of the newly conquered territory, and to some extent continues to govern relations between the government of modern Canada and the First Nations. Included in its provisions was the reservation of lands west of the Appalachian Mountains to its Indian population You have to remember that England had finite resources. After winning New France they mostly wanted to get the troops back home and didn't want a bunch of colonials starting another conflict with the native tribes. Although by withdrawing troops the Colonials felt quite comfortable ignoring order from across the ocean and weren't so interested in paying the taxes that were ostensibly to pay for the war the british just fought for them. Some say this is when the revolution really happened as the people began to ignore the kings laws as they pleased."
] | [
"If your next door neighbor is trampling flowers in your backyard, and your much larger, much bigger neighbor from across the street decides to try and stop him, it's in your interest to just let him do that, whether with implicit or explicit approval. ... especially when you can't get to that corner of the backyard yourself, because you're still dealing with your stove being on fire and the vacuum going out of control."
] |
When people say stars and nebulae are formed by gas and dust, what exactly is the dust? | [
"Carbon compounds and silicates are still around in space, and they can form *very* complex structures. The environments where they form can allow for very different chemistry than is encountered on Earth, even at high vacuum, and the structure and formation of dust remains a large and active topic of research. It also scatters and absorbs light in different ways than gas, so it's important to understand the dust in order to correctly remove its effects when doing all other areas of astronomy. Dust is ubiquitous, causes important effects, and is poorly understood."
] | [
"Bread is about 50% carbohydrate (sugars, starches, and fiber), 10% protein, and I have to assume that most of the rest is water weight. That's fairly low in water and protein, so bacteria don't grow well on it, but better water scavengers like molds can grow here. Bread also has trace elements that are needed for life (like Iron, for example) that come from being made of other living things (wheat, eggs, yeast). Sugar has no protein content, so it is extremely nitrogen poor. It is a relatively pure chemical sample (sucrose). You need nitrogen for earthling life, and probably all life. Dry pasta has a very low water content, and this discourages all growth. Same with crackers. When you add water to these items... I dare you to leave it on a counter for a week and then eat it (please don't)."
] |
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