ASM057 Special Edition: Gravity Waves

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it's all about gravity waves on this special edition of ask science mike

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welcome to ask science mike the weekly podcast where i answer your questions about science faith and life and this week i got over 200 of the same question about gravity waves so we're going to do a whole episode on that and also coming up later this month we're going to do an event called lost and found in phoenix and los angeles stick around at the end of the show to hear more about that but for now let's get it started hello science mike my name is ben my brother just recommended this show to me about a week and a half ago and i've been listening to it a lot really enjoying it i'm super interested in philosophy and theology and science but these are all areas that i'm constantly wanting to grow in i don't feel like i've got a firm grasp on all of them so your show is perfect for me so thank you so much for everything you're doing really really enjoying it one of the particular areas i am very deficient in is my understanding of physics recently on social media i've been reading a lot about gravitational waves in this new discovery and i'm not really sure sorry mind the pun about the gravity of the situation with this but i was wondering if you could illuminate what the the situation highlights for us and what we know about physics and what we know about einstein and all that jazz so if you could talk about this that would be really awesome and i'd really appreciate that thanks so much we live in an era of media hype but it's honestly difficult to overstate the importance of this announcement regarding gravity waves this is a huge deal and i was really encouraged that my audience all of you listening found it to be such a big deal you actually crashed the voicemail system i used for recorded questions you filled up my mailbox with questions about gravity waves and the email questions absolutely has more questions coming in faster than i've ever had all the same question remarkably what is the deal with gravity waves well if you think back just a little bit into the past remember the announcement of the higgs boson and that was a huge deal that the large hadron collider the lhc had gained statistical confidence that they had detected the higgs boson this predicted particle that was a manifestation of the higgs field a completely at the time unverified theoretical framework for how everything in the universe has mass surely enough as we increased our particle energies in the large hadron collider the higgs boson showed up as predicted which was an incredible validation to the standard model of physics and that's how science works you build models based on observation you look at reality and you figure out the numbers behind it and if your model is good it will not only explain the world as we see it but it will also make testable predictions about what we haven't seen yet and so the higgs boson was this incredible validation of the standard model of physics that the math was so good that it revealed the unseen and then when we eventually saw the unseen it was what we predicted and gravity waves are a similarly powerful validation of einstein's views on space time popularly called the theory of relativity this is a huge deal now this is kind of the final big prediction einstein made that has been validated all of einstein's predictions over time have been validated for example one of the things that einstein's relativity predicts is something called gravitational lensing where galaxies or black holes or very massive structures or objects in space will actually bend light rays in the same way the lens does we've seen that einstein's really strange predictions about the nature of time have been validated and underpin a lot of our technologies and if we're going to talk about gravity waves i think we need to kind of cover the theory of relativity and that's why i'm only doing one question on this week's show this is not going to be a normal five minute or seven minute answer i'm going to take all the time we need to cover this and it's going to be a little brain bending if you're not familiar with physics and cosmology so i cleared out all the other physics questions i had on deck this week because i don't want anyone to get a nosebleed as we contemplate these very counter intuitive ideas now in terms of gravity waves it has been a really bumpy road detecting them there's been a lot of attempts over time and i was actually afraid to tweet the findings about gravity waves this week until i saw some other voices weigh in because there's been so many false positives but before we get into all that let's talk about the theory of relativity it has two parts okay the first part of relativity is called special relativity and special relativity says something that's relatively simple and that is the speed of light is the same in all reference frames or from all perspectives when i say reference frame just think perspective or point of observation now that doesn't sound like a big deal you would imagine intuitively that the speed of everything is the same in all reference frames but the fact that the speed of light is the same in all reference frames actually undermines our intuition it's a really counter-intuitive result and what i mean is that the fact that the speed of light is constant means that time actually slows down as your speed increases compared to a slower moving observer i'll say that again your perception of time slows down as your speed increases compared to a slower moving or stationary observer it's the only way light can always be measured traveling 186 000 miles per second from every perspective 186 000 miles per second it's mine blowingly fast now because that number is so high it can be hard to understand the effects of relativity so we're going to do a thought experiment and we're going to change the speed of light so we can understand how this could be so so let's imagine for a second that instead of 186 000 miles per second light only traveled a hundred miles per hour about the speed of a really fast fastball in baseball uh and i had to google that i'm not really a sports guy but apparently a hundred mile an hour fastball is a big deal it's also a nice round number we can uh take apart easily so imagine for a second that you're standing on a pitcher's mound in a baseball diamond and a photon a particle of light passes you going the speed of light which in this case is a hundred miles an hour now imagine you had a device that let you measure the speed of photons and as you measured this photon as it passed it was a hundred miles an hour which is totally obvious the same thing would happen if you threw a hundred mile an hour fastball and measure it with a radar gun it would measure 100 miles an hour we're all clear here now here's where it gets weird imagine someone is driving in from the outfield on a go-kart at 50 miles an hour 50 miles an hour is half of a hundred miles an hour right so we would imagine that if someone was on a golf cart or a go car traveling 50 miles an hour and they measured the speed of a baseball traveling 100 miles an hour they would measure that speed is what 50 miles an hour because they're going half as fast as the baseball this is you know how reference frames work it's the same way that to you on a train if you tossed a baseball at 10 miles an hour and the train was going 80 to you on the train the baseball looks like it's going what 10 miles an hour to someone outside watching the train go by though it looks like the fastball's going 90 miles an hour 80 miles an hour plus 10 miles an hour so we're just doing the opposite we're subtracting and that would work for baseballs if you measured the speed of a hundred mile an hour baseball from a go-kart going 50 miles an hour in the same direction the speed of the baseball would appear to be 50 miles per hour now if the person on the go-kart instead of measuring the speed of a baseball measured the speed of a photon what speed do you think they would measure well our intuition would say that light would appear to be going 50 miles an hour but what we find in physics is if the speed of light was 100 miles an hour both the person on the pitcher's mound and the person in the go-kart would measure the same speed for that photon of 100 miles per hour now how is that possible there's only one way to make it possible and that's to change the rate at which each observer experiences time the person in the go-kart would experience time half as fast as the stationary observer so every one second that ticked by on the wrist watch of the person on the pitcher's mound only a half second would tick by in the go cart but because of that they would both measure the same 100 mile per hour speed for that photon in our imaginary universe where the speed of light is 100 miles per hour now thank goodness the speed of light is not 100 miles per hour or else the world would be weird it would be very difficult for us to synchronize events and meetings and clocks because every minor change in velocity would significantly alter the passage of time but luckily in our universe light speed is not 100 miles per hour it's a hundred and eighty six thousand miles per second and that means the effects of special relativity aren't really relevant at everyday speeds or or gravitational energies you see we have validated the effects of relativity at scale though gps satellites are traveling so fast compared to an observer on the earth that their clocks do drift over time more than a normal clock drift and for gps satellites to function engineers had to incorporate special relativity into the software and mechanisms that drive gps or else that blue dot on your iphone would drift over time and become less and less accurate special relativity as weird as it is is a demonstrable fact in our universe isn't that that's crazy if you think about it now that's just special relativity which is one part of einstein's larger theory of relativity which is often called general relativity general relativity incorporates that fixed speed of light from any reference frame into a larger predictive model about how the universe is structured general relativity says that space and time are both part of a single fabric called space time that there is no separation between spatial and temporal dimensions in our universe i'll let you think about that for a second so you have space and time both part of a single fabric and that this fabric of space-time is warped or stretched by gravity so you can imagine our sun this massive massive object at the center of the solar system is bending or warping space-time like a bowling ball that's been set on a sheet that was stretched tight you can imagine that right just imagine four friends stretch out a bed sheet as tight as they can and they drop a bowling ball in the center of course the sheets going to sag now if you had a ball bearing and you rolled a ball bearing across a sheet that was stretched tight it would roll off the other end but if you add that bowling ball into the center of the sheet that little ball bearing can't travel in a straight line anymore it's going to get it's going to turn because of the curvature of the sheet well that's what gravity does to space-time itself that's why our planets are locked in orbit with our sun it's why the moon orbits the earth it's why you stay on the earth surface the curvature of space-time due to gravity causes you to accelerate towards mass now why doesn't the moon crash into the earth because the moon is traveling fast enough to be in free fall that's equal to the curvature of space time so the moon is constantly falling around the earth and the earth is constantly falling around the sun the sun is constantly falling around the center of the milky way galaxy general relativity presents a very strange view of the universe but one with very powerful predictive accuracy now because space and time are warped by gravity it's not just space as you get into very steep gravity wells time is stretched as well so for example if you get very near to a black hole's event horizon time starts to slow down from your perspective compared to someone who's not trapped in that gravity well now some of you this is a review but i'm imagining for most of the audience this is mind-bending stuff but i wanted to just get this two main ideas to you one special relativity tells us that the speed of light is the same from every reference frame and two general relativity tells us that gravity can bend space time and that's where gravity waves come into play so if mass can warp space through gravity then very very large masses can ripple space time these are gravity waves just imagine a bowling ball dropped into a pond versus a pebble you drop a pebble there's not going to be much of a disturbance if you drop a bowling ball into a pond that's going to make pretty significant waves now imagine you dropped a boulder into a pond that's going to make huge waves travel in all directions and gravity waves are ripples in space time itself in the same way that sound waves are compression waves in our atmosphere the atmosphere itself compressing and stretching because of the energy of movements and vibrations the you're hearing me right now because my vocal cords shake and cause waves to travel through the air and strike this microphone gravity waves are the same thing but with space time itself and because of einstein's incredible predictive power because relativity's been validated so many times we've been looking for gravity waves since einstein's days and i held off tweeting about last week's discoveries because there have been so many false claims that say someone has discovered gravity waves in the history of physics their earliest attempts involved aluminum tubes and you know almost uh lone rangers trying to win a nobel prize but even more recent well-funded operations like bicep2 have produced false positives the fact is gravity waves are hard to find and there's a reason for that detecting gravity waves is really hard because you're talking about waves that distort the very fabric of space time again just like sound waves or manifestations of compressed atmosphere gravity waves are manifestations of compressed space time and these ripples are tiny because gravity is very weak when compared to other forces in physics now i know that sounds strange here on earth where you feel the intense pull of gravity every time you climb a flight of stairs for example you climb enough stairs and you become very aware of earth gravity well but just think about how small a magnet is needed to pull a nail off a table and when you do that that magnet is attracting that nail is pulling that nail more powerfully than an entire planet's gravity gravity is weak compared to other forces in physics and because of that gravity waves are very very small very difficult to measure now that's uh not the only reason that gravity waves are hard to detect because think about this imagine you had a ruler that was so accurate it could measure the width of a proton just a tiny tiny measurement you might think that such an accurate ruler would be small enough to help you measure disturbances in space-time but this is the problem it doesn't work because gravity waves wouldn't just stretch a proton when space-time is bent they also stretch the ruler itself the same amount in order to measure gravity waves you need a ruler that is immune to the effects of warped space-time or at least more resistant something that is constant may even a constant and that's why scientists turn to the constant that defines our cosmos according to special relativity remember the speed of light is the same from all reference frames and so a ruler made of light may just be able to reveal gravity ways now kip thorne was one of the founders of ligo which is the laser inferometer gravitational wave observatory you may recognize his name from the movie interstellar he's the physicist who helped those filmmakers model wormholes and black holes with such accuracy dr thorne along with ronald drever and raynor weiss had an idea to build a massive light based ruler to measure these ripples in space time we call gravity waves to do this they built two stations in opposite corners of the country louisiana and washington state each one consisted of two four kilometer tubes built at right angles to one another these tubes are evacuated they have a nearly perfect vacuum because even air molecules would create too much turbulence for the measurements of these instruments to be accurate so inside these evacuated tubes is a laser emitter and some very carefully constructed and placed mirrors that send a single laser down both tubes and back where they converge into something called an interference pattern one of the fundamental things that occur because of the wave particle duality of light i won't get into that we maybe can talk about that on a future episode all you need to understand is that when light beams recombine or any beams of light combine they create an interference pattern and what they're looking for because these two tubes are moving in different directions they would be stretched and pulled at different times very slightly different times by gravity waves and therefore they would reshape or modify the interference pattern that showed up on the detector it's a very brilliant idea that was very expensive to operate i mean it's an incredibly accurate system it can detect fluctuations in space-time smaller than an atom but that sensitivity makes it a pain in the neck to operate you know building the detector was hard enough it required new engineering and optics mirrors that were more accurate and consistent than had ever been constructed but every single vibration can affect the interference pattern on this detector researchers had to learn not only how to construct this thing so it was the most immune from environmental vibrations and impacts but also how to weed out the signals that got through any precautions they could take that were earth-based phenomena because of that ligo is the most expensive project the national science foundation has ever been a part of it's had numerous cost overruns and it's fallen behind schedule many times but it was only a few days after it had been running at a retuned higher sensitivity known as advanced ligo for a few days when it first received this signal now that sound is an audio manifestation of the difference in the interference patterns that allows our ears to hear the ripple of space-time itself it's an amazing amazing sound but when we directly convert it that way the pitch is relatively low and it makes it difficult for our ears to really pick out the finer points of the signal so next i'm going to play a pitch shifted version of the same sound that's more in the sweet spot of human hearing that is the sound of a gravity wave the first ever detected by humanity it was formed when two black holes merged after a period of mutual orbit where they spun around their mutual center of gravity at near light speed each of these two black holes were incredibly massive dozens of times the mass of our own sun when they merged their combined mass was about three stellar masses smaller than their original separate values they lost the mass of three of our own sun as they merged part of that lost mass became the energy that was able to send a ripple through the cosmos a gravity wave i mean just think about that two black holes 1.3 billion light years from the earth sent a ripple through space that we just heard it's been 1.3 billion years since the event and yet today we can hear it with our own ears this is a huge deal and not just because it validates einstein's theories an even bigger more important component of the discovery of gravity waves is that it gives us a new means to peer into the cosmos you see for all of history we've looked into the sky and therefore into our past with light and other forms of electromagnetic radiation telescopes radio telescopes even gamma ray detectors all of them sample photons that are traveling through space it's a really miraculous ability if you think about it because of light's limited speed the farther away we look from our earth the farther back we see in time that allows us to see stars and galaxies as they were long ago when you look at the sun you look eight minutes into the past when you look at saturn you look 80 or 90 minutes into the past but when you look at the andromeda galaxy you look two and a half million years into the past because the photon that strikes your eye on a beautiful autumn night left andromeda two and a half million years ago now the farthest galaxies we see via space-based telescopes are billions of light years away and therefore billions of light years into the past we're able to see galaxies as they were over 10 billion years ago and that lets us confirm via observation our theories about how the universe operates and how it was formed we can look with our own eyes because we can sample signals from events that happen long ago just by catching photons but there's a limit the farthest we can see with photons is something called the cosmic microwave background radiation and this radiation is a signal from about 380 000 years after the big bang it's the first moment the universe had cooled down enough to allow light to travel through it without being annihilated and because of that the cmbr the cosmic microwave background radiation is a baby picture of our own universe when it was just 380 000 years old because it was right where scientists predicted it would be before it was discovered the cosmic microwave background radiation is some of our best evidence for the big bang and the overall age of the cosmos but it also acts like a curtain that prevents us from looking farther into the past well at least it did until now because the cosmic microwave background radiation may be a curtain but gravity waves are like a sound that can pass through it i mean just imagine that for a second imagine if the room you were in was separated from the next room by a curtain that curtain if it was thick enough would prevent all light from passing through but you could hear someone laugh on the other side of the curtain you could hear someone clap their hands you could hear a conversation and because of that you could observe the events in the next room even though you couldn't see them so you can imagine with more sensitive detectors we'd be able to hear the gravity waves that came from the very moment our universe expanded from singularity we would be able to hear the big bang more than just a baby picture such a signal would be the cry of a newborn universe at the very moment it came to be a signal we could sample and measure from the very beginning of time this is why gravity waves are such big news this is why scientists are so excited and scientists are already working on plans for a space-based ligo called the evolved laser inferometer space antenna we basically put three satellites into the earth's lagrange points which are points in space where the sun the earth and the moon's gravity cancel each other out and that would give you a stable platform to use lasers and interference patterns to find much smaller signals than we've been able to find here on earth's surface potentially this technology will let us hear gravity waves from the big bang and therefore for the first time may let us hear what really happened in the beginning know that was a heavy answer if you'd like to learn more about gravity waves and maybe get some visuals it is relatively difficult to understand many of these concepts without a little uh assistance from your visual cortex just go to ask sciencemic.com i've got links to some articles and some videos that will tell you more about gravity waves and what they mean in a visual way so that's on ask sciencemic.com as i mentioned at the very top of the show there's some really cool events coming up i'll be in phoenix and los angeles uh at the very end of february to do an event called lost and found if you've heard episodes six and seven of the liturgies podcast this is a dramatic portrayal of the content of those episodes so i come out and tell my story of faith lost and found in small vignettes that are interspersed with really beautiful music by gunger and the brilliance including strings i mean it's a gorgeous event we also do some guided meditations and the goal here is to lead you on your own time of contemplation and discovery with how you relate to god how you understand god we've done lost and found a few times people have told us it's one of the most powerful events they've ever been to now in phoenix we're partnering with a church called trinity mennonite church and they're doing something really spectacular they've bought the show they've made it so we can afford to come but they've also covered those costs and the reason they've done that is they want all ticket sales 100 of ticket sale proceeds will go to the international rescue committee that's a relief organization that deals with the needs of refugees so if you come to our event you'll be supporting that cause now there are vip tickets available for the event in phoenix and i recommend that you buy them because not only are you going to offer more financial support to the international relief committee you're also going to come to a vip event but instead of like a meet and greet or something like that you're going to go with us to this charity and volunteer and support people in need that's that's the vip event is mutual service it's the most literary thing i could imagine so incredibly impressed with the work of trinity mennonite and the international rescue committee so if you're anywhere near phoenix i mean anywhere near phoenix right now go to ask sciencemike.com click on events and then click on that phoenix event and learn more if you go to the liturgist facebook page there's actually video you can watch that will tell you more about the irc it's going to be an incredible event for an incredible cause and we'd love to see you lost and found in la if you don't have tickets hurry up the first showing we're doing two events that night the first one's already sold out all the tickets are gone and the second event is selling well so don't wait hurry up get online go buy your ticket they're very inexpensive we'd love to see you in los angeles or phoenix for lost and found now i have a ton of events coming up i'm going on tour with gunger and all those events are on my website but i've also just got a lot of bookings i've got an event in ventura california with peter ends i'm going to be going to minneapolis and doing an event with greg boyd so there's lots of opportunities to see me all those can be found by going to ask sciencemike.com and just clicking on the events button you'll get a list of everywhere i'm going with all the details there are a few events i haven't put up there yet because there's not enough details but keep watching there's going to be a chance to see me pretty much everywhere in the country this year and that will only continue to accelerate toward the fall and we get closer to my book launch which i'm really excited about i finally turned in the manuscript it's done uh i feel like i lost 100 pounds because i don't have the weight of that manuscript on my shoulders anymore but lots of opportunities to get together and i'd love to see you this year now i also need questions this show is your show if there's no questions there's no show now let's be honest there's plenty of questions but new and interesting questions are what drive the program so if you go to ask sciencemike.com you can fill out a form that submits a question to me you can record a question which is how you hear people's voices on the program if you'd like to be radio podcast famous no big deal just record a question you come on the show you can also submit questions using the hashtag asksciencemike on social media i mainly check soundcloud youtube and twitter with a heavy heavy emphasis on twitter it's easiest for me if you're going to do a recorded question if you use the form on the website it just saves me a ton of time also the show is made possible by the generous financial support of my patrons on patreon they run the show i don't run the show how do questions get on the show my patrons pick them so if you'd like to be involved in shaping the discussions we have on ask science mike if you'd like to keep making it possible for me to host this open conversation about science and faith just go to ask sciencemike.com and click on the patreon button and learn more a dollar a month helps five dollars a month is huge i would love it if the show was sustained on nothing but one to five dollar a 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people in the world through this program i wish the rest of society was so thoughtful and so civil i want to thank andrew golucky for his hard work on pre-production in the show i want to thank greg nordin for his producer hat and the sound design that he does making the show sound good sound listenable and of course i want to thank my friend jeb for writing composing recording the ask science mic theme song which is so catchy that people sing it to me in the airport all the time it's i just love the puzzled look on people's faces who aren't part of this inside joke anyway thanks for listening everybody i hope you enjoyed these words on gravity waves and we'll return with a more normal multi-question episode next week [Music]