Detecting Gravitational Waves

but I suppose the show must go on. Well yeah, and Joe, it's it's kind of it's kind of fitting that that you are a little out of play here, right because we're going to revisit a topic that Lauren and I talked about, gravitational waves, and you weren't here for that episode. God, just act like I'm not here. So yeah, so mentally you're you're again not in the room. You're on vacation. You're always wonderful and find an excellent Yeah, I'm sure that you'll be a joy as always. But hey,

gravitational waves, this was some big this month. Yeah, huge news. And actually it's funny because the discovery happened in two thousand and fifteen. But as is the case with any really you know, careful, responsible scientific inquiry, it took some time for scientists to verify the information the data they had gathered before they actually announced what they had found.

You know, it did, but I don't know if you all noticed it, if you follow the the I don't know, science writers on Twitter or or the science press in general. There were several rounds of rumors flaring up where some prominent physicists or cosmologists would sort of like drop a hint saying like, I think they found gravity waves. Yeah, I know, you're gonna you're gonna get out of your

red pin about that a little bit. Yeah, And and so somebody would print a story about that, and the rumor mill would flare up, and then it would all end with well, I guess we'll just have to wait until they announced their findings and see what happened. But it turned out that the rumors were in this case true, right. There was a very very strong, very well established piece of evidence for gravitational waves in the universe. Yes, a a detection that appears to be pretty much air tight.

So uh, And that was announced on February eleven. We were all eagerly waiting for the announcement. In fact, many of us were following it live as it was happening. Joe, you were tweeting about it live as it was happening. As I recall, I think I just I retweeted. Some people got you. I wasn't. I wasn't live tweeting, and you were tweeting. You weren't undead? Are you undead? Is this what this called? Isomie a little bit undead? I hope you all both brought across well at any rate.

The last zombies. Okay, go ahead if you if you're really cross with a zombie, they take note. So we originally talked about gravitational waves back in September two thousand and fourteen, and in that conversation we were talking specifically about BICEP two, which is a telescope that's in the Antarctic. Yeah, and if you remember some time vaguely in the past, either this podcast or just other general news announcements a few years ago, and you're saying, like, wait, I thought

they already discovered gravitational waves. There is a reason you're remembering that. Yeah. Yeah, Well they said, hey, guys, I think that we we we think that we discovered gravitational waves. This is so great. And what they actually discovered was spacedest yeah, or at least space dust was enough of a factor to throw the results into serious doubt. But we'll talk about that a little bit more later in the podcast. This time, we're going to really be focusing

on what Lego found. Uh Ligo is a pair of observatories, and we'll talk more about those in a minute. But before we get into any of that, perhaps it's best to actually take some time to talk about what gravitational waves are in the first place, and to understand that you've gotta look back in history, all the way back to nineteen sixteen, which is when Albert Einstein published his his theory of general relativity, had been working on it

since nineteen o five. Right, So, Alfred B. Iimstein was out on a train one day, hurling axes out the window at passing herds of buffalo and he never give you cold medication before a podcast. And he noticed that as he tossed each ax, it arcd towards the ground instead of flying off in an infinite direction in which he threw it. So why does that happen. Alright, ignoring everything that Joe just said, Here's here's what Einstein was was considering. He had been really thinking hard about the

nature of the universe. Uh. This was part mathematics, part philosophy, part just uh just using logic to its inevitable conclusion. And it was incredible. The theory he came up with, it was it was phenomenal, and not just phenomenal. But over the years, so much of that theory has proven to be accurate to what we see in reality. That you know, we we just keep on supporting the various predictions that were made, and gravitational waves were one of

the predictions made in the theory of general relativity. Uh. He he had argued that that the universe is made up of uh space time continuum. You've probably heard that if you've ever watched any Star Trek, you've heard about the space time continuum. But the spacetime continuum is is sort of this idea of space and time together forming kind of a fabric of the universe and matter or to be really just just to to talk it in the terms he used, mass can change, can can warp spacetime.

In fact, it does warp spacetime. The presence of matter warps spacetime. So the most common analogy that you tend to see is that imagine you've got a trampoline and you put a bowling ball on the trampoline. It ends

up making a dimple in the trampoline. It sinks down where the bowling ball is resting that here here, the trampoline being spacetime and the bowling ball being say a star, yeah exactly, let's let's a star, black hole, anything that's got a lot of mass, and uh you that would show you how the trampoline warps around the bowling ball,

like spacetime warps around an object of great mass. Keeping in mind, of course, that we're using more or less a two dimensional representation to talk about three dimensional concept. But it's really hard to imagine a three dimensional concept. Really, Yeah, that's true, because you're talking about time. It is true. But then if you were to take a marble, let's say,

and roll it across the trampoline. Now, if it were if there were no bowling ball on it, the marble would just roll from one side to the other, assuming that you're on level ground and all that. But with the bowling ball. There, it's gonna start spiraling inward towards the bowling ball. And Einstein argued that what we see with gravity, with with gravitational pull between like a star and a planet, or even the center of a galaxy and all of the star systems, that's how they behave

they move in that same spiral. And uh So, now one difference you might observe is that you think, hey, well if I did that on a trampoline, and probably marble would probably only spiral around the bowling ball three or four times before it crashed into it. There, I would guess the difference is going to be in this example friction between the marble and the trampoline. We also speak and orbits in space being you know, almost negligible

amounts of friction. Yeah, that's definitely, that's definitely the case. It helps. So what we see here is that spacetime curves around objects and then be building upon that. Uh Einstein said, if you have a large mass undergo a violent change, either it changes shape or it changes its motion in some way in a dramatic way, it creates these ripples in space time that propagate outward at the

speed of light. And these are gravitational waves. Um. So it's actual ripples in space time itself, and it's kind of like an electromagnetic wave, and that it moves at that speed of light, but unlike electromagnetic waves, it can't be absorbed and it can't be scattered. Yeah, it behaves in that way, more like a sound wave. Yeah, exactly. So if you think of sound waves, where when you hear a sound, what you're actually hearing is the motion

of air molecules. Those air molecules are being compressed by an oncoming wave and then they expand again afterward. It's very similar to that, except we're talking about the fabric of reality itself. Now, let me play Jonathan for a second and be pedantic. It wouldn't necessarily have to be air molecules, would it be whatever medium that the sound

is traveling through. That's true. Yeah, it could be solid wood and it's still has um and we should we should put in that Einstein himself wasn't entirely sure about this gravitational wave stuff. He kind of flip flopped on it a few times, but always came back around to support it. So I think that he himself would be sort of tickled that we a came up with a way to detect them and be have actually detected Yeah.

I think he would be flabber guested because I the impression I get is that Einstein was fairly certain because the nature of gravitational waves, they would be undetectable. There there'll be no way to directly observe them because they are invisible, there's nothing. They're not like electromagnetic radiation, where you've got an actual visible spectrum. Um. So I think that would have really shocked him that we had come up with a really clever way of detecting the presence

of gravitational waves. Now, Jonathan, why is it that you have a bone to pick with anybody who calls this most recent discovery the discovery of gravity waves? Well, because it's wrong. So gravity waves you told me all about the wrongness. Gravity and gravitational are two different things. With a gravitational wave, you are talking about this ripple through space time that travels outward at the speed of light. With gravity waves, you're talking about a wave that exists

due to gravity. It's something that you would find on a planet, either in some sort of fluid system, whether it's an atmosphere or like a body of water. So, um, let's say you've got an ocean and you've got wind blowing across the surface of that ocean, it starts to disturb the water. Gravity is pulling down on the surface of that water, and uh, waters buoyancy is acting in opposition to gravity, and that combined with the wind, creates a wind driven um wave. That would be a gravity wave.

It's a wave that exists because gravity is there. If there were no gravity through would even be a body of water there. Uh. That is a gravity wave totally different from a gravitational wave, just a physical wave that

you can observe through some form of fluidic system. And so if you ever hear someone say gravity waves of gravitational wave as a matter of shorthand they're technically being incorrect, you should probably find a polite way to say, maybe you meant gravitational wave, or you could be like me, and there's no polite way to say that. Yeah, I gave up on being polite years ago, so I just tried to caution other people not to make the same choices I made. Um. But yeah, there's some some other

interesting things about gravitational waves. They pass through stuff. So like we said, yeah, yeah, they don't act like electromagnetic waves. Yeah, they don't get absorbed or reflected, so they just poop keep on going. So if you've got, for example, a planet between you and electromagnetic radiation such as light from the Sun, you will experience in eclipse because the planet blocks it. But it will not block these gravity waves exactly, won't.

It won't eclipse the the movement of waves toward you. The waves will get weaker as they propagate out over distance though, yes, and uh So if you're talking about a gravitational wave that has you know, has happened because of some massive event that's a billion light years away, they are very very faint by the time they get to Earth. Uh And that also leads to why they've been so tricky to detect. Not only are they invisible,

but they're not very strong. So we have to look for gravitational waves that have been caused by really really big events, like in the case of the one that Ligo detected in September two thousand fifteen, it was the collision of two black holes. It's a pretty big event. Others could be two neutron stars that are orbiting one another rapidly, which would create kind of an oscillating and continuous a series of gravitational waves. Um or it could be like a supernova exploding that to do it. A

big bang that would do it too. In fact, that was what my step two was looking for, was the evidence of gravity waves from the era of the Big Bang. I just caught you in it. What, oh man, I I I stand correct, I sit corrected here in to eat, Thank you well, and as soon as I get the foot out of my mouth, I will start chewing upon the hat. Yes, gravitational wave not gravity wave. No, it's true that they have been so difficult to detect and that we've had to come up with very interesting methods

of trying to detect them, involving laser interferometry. Yeah. So here's here's something that's really cool about a gravitational wave because it's this ripple in space time. It actually is a small you can think of it like a small fold in spacetime, right, and that means it can actually change the distance between two points by compressing that distance

or expanding it like a rubber band. So you've got like a piece of elastic h or if you prefer, you know, just just imagine that, Um, Joe, you and I are standing across a football field from one another. You're on one end zone. I'm in the other end zone. Their en zones in football, right, I'm just looking for There's no help from the one with the oblong spheroid, right, Yes, that's it. Or you know, a soccer field if you prefer, But then you know where at either end gravitational wave

passes through. Let's say it's a massive gravitational wave, something way bigger than we would ever actually observe here on Earth. What would appear to happen is that Joe and I from our perspectives, it would look like we got closer and then further apart, and then closer and then further apart, without ever taking a step in either direction. That the are, the world itself has compressed and expanded around us because of this fold in spacetime that's passing through, which sounds

like some serious like matrix style stuff. But either fortunately or unfortunately, depending on how you know, stable you like your reality, that's that's that kind of dramatic change is not what we observe from gravitational waves, right, Not at all, not even remotely in the same football field as it were. Uh No, Instead, if you were to have something like a supernova explosion, and I should say an asymmetric supernova explosion for reasons I don't understand, a symmetrical supernova does

not a supernova explosion does not generate gravitational waves. I don't know why I was reading it trying to find more information, but it got to a point where the astrophysics got way too complicated for me to understand. However, what I do understand is that if there were a supernova explosion in our galaxy in the Milky Way, the gravitational waves generated from that would only be powerful enough to change the distance between Earth and the Sun by

the diameter of one hydrogen atom. That's how much it would oscillate. Oh yeah, okay, you probably would notice. So this is like a princess and the p kind of thing, isn't it. Yeah, definitely, definitely on that level. Obviously, we need to build a more sensitive princess. That's that's the you know, that's entirely the plot. Yeah, yeah, we're about a mattress. You know, it's all musical about that. Oh I didn't build a robot princess, any number of mattress.

They just they just uh collued to make her uncomfortable so that she she complains about the the lumpiness of the mattress, and it turns out that there's not just a p under there. There's also a suit of armor and a shield. Spoiler alert for any of you who are really looking forward to what's upon a mattress. Yeah. But but but I suppose they did kind of create like a laser princess. So yeah, but we'll get into that.

So anyway, So so I just mentioned that if you're looking at the Earth and the Sun, you're talking about the differ prints of the diameter of an hydrogen atom in the distance, which is incredible to think about. But that that change, that difference in distance gets smaller as you get two smaller scales. So let's talk about if you were on Earth and trying to measure this, because this gets to why it has been so challenging to detect gravitational waves here on Earth. Okay, don't use a

football field analogy. What about the need to how about the beginning and end of the line for space Mountain. That's a queue that goes like, yeah, that one already loops around back on itself in weird ways. Yeah, it's not really gonna work. No, I don't need to make that comparison. I was just to to establish the weirdness of what happens. But no, I wanted to just talk

about the scale. So if you were talking about here on Earth and you're trying to measure that that change in reality, that change in distance because the spacetime continuum is being folded in this ripple. Uh. If you had two objects that are about a column butt are apart, the change in distance they would experience due to that gravitational wave would be thousands of the diameter of a proton.

So take a sub atomic particle and go a teeny tiny fraction of the diameter of that subotomic particle, and that's how much difference in distance it would experience. Get out your your proton knife and your proton measuring set, and it turns out your ruler is not going to be terribly helpful in that case. So that is one of the reasons why it's been so incredibly challenging to detect the presence of a gravitational wave. And and we we've had a few leads, or if you prefer, a

few false starts in detecting them throughout history. Back in nineteen sixty nine, University of Maryland physicist Joseph Weber created this this six foot aluminum cylinder that he claimed would act like an antenna for gravitational waves. He said that when such a wave hit the cylinder, it would ring like a tuning fork, but nobody else could replicate his results.

It was a kind of neat looking device, though. There's actual video of this, and it look kind of like a mirrored two inside another tube, like there was like some sort of crazy physics disco going on inside there. Uh, or at least that's what I like to think. Back in nineteen seventy four, there are a pair of scientists in Puerto Rico who saw a binary pulsar system and they looked at the theory of general relativity, which predicted that such a system would gradually lose energy due to

the too emitting gravitational waves. Some of its energy would go into creating these gravitational waves, and because you have a system losing energy, it would start to lose speed. And so they said, well, based upon this prediction, we should observe this change in speed as long as we keep an eye on this binary pulsar system. So they

tracked it for eight years. At the end of the eight year period, they said the behavior of the binary pulsar system was completely in line with the predictions from general relativity. He said, it is behaving precisely the way it would if, in fact, gravitational waves are reality. Therefore, this is in support of gravitational waves. And even since then, over the forty years of observations that have happened with this binary pulsar system, those predictions continued to be supported.

So that was great, you know, indirect evidence of gravitational waves, saying, well, if they don't exist, something else must be happening for this system to slow down the way it is. But the thing that makes most sense is that Einstein was right. Then we move ahead quite a bit. Let's talk about BICEP two. Now, BICEP two was going a different way

about looking for gravitational waves. They were specifically looking for evidence of UH that would support a hypothesis called cosmic inflation, and inflation is a big deal in physical cosmology today. This is I think most physical cosmologists look at inflation is very promising theory. Yeah, And the whole reason why we have this this idea in the first place is to explain why the universe appears the way it does, while also trying to reconcile that with the Big Bang theory.

Because I'm not going to get too far into the weeds here, but the basically the hypothesis says that about ten to the negative thirty six seconds. So take a ten and then take a decimal point and move that thirty six places to the left. Get get that proton knife out again, did up a second, right, That's that's where you get down to the teeny tiny, tiny tiny fraction of a second to about ten to the negative

thirty three or thirty second power seconds. So so in an instant, as far as we're concerned, into an instant, Yeah, that at that moment, that's when the universe underwent rapid expansion, far greater than the rate of expansion it currently is going through. And it's expanding fast today. Yeah. Actually, then it's picking up speed, which is a little uh, at least according to our measurements, it is picking up speed.

But that's that's something that we hope gravitational waves will help us learn more about in the future at any rate. A scientist named Alan Gooth proposed a hypothesis to explain why the universe looks the way it does and stay in line with the Big Bang theory. It was kind of like, well, in order for us to be where we are now based upon the observations of the universe we have made so far, and in order for the Big Bang theory to make any sense whatsoever, there had

to be this period of cosmic inflation or else. It just doesn't work out. The math doesn't work out. And in a way you could argue, all this is almost like a placeholder, except again, it's kind of like Einstein. It's using logic saying, well, we we know about this, we're pretty sure about this other thing. But in order for those two things to reconcile, this other, this third thing must have happened at some point. Yeah. Yeah, it's

theoretically solving for X in this equation. Yeah, and if you fast forward three thousand years after the Big Bang, you then have the emergence of the cosmic microwave background or c MB. Now, this is a radiation that's sort of a fingerprint left over from the from the era after the Big Bang. It's from it's when the universe was still seeing birdies. Like in the cartoon, universe really wasn't seeing anything. It was so dense that even light

couldn't pass through it at this point. Um, but it is. It's sort of the remnant of that era, and we can we can detect the cosmic microwave background. So BICEP two I didn't mention to se either. BICEP actually stands for background imaging of cosmic extra galactic polarization. Was looking

for polarized cosmic microwave background radiation. The idea being that gravitational waves should have aligned certain segments of the CMB, so if you could detect that, then that would be indirect evidence of gravitational waves and therefore also indirect evidence of this cosmic inflation idea, because something as dramatic as cosmic inflation would have generated gravitational waves and they would have left their mark on something like the CNB, and

they the team thought they found it. They actually thought they found it a couple of years before the news broke. They spent years trying to verify the information they found to make sure that they eliminated other possibilities. They went public with the UH the announcement I think March of two thousand fourteen, and it was September two thousand fourteen when other teams came out and said, we think it might be the presence of space dust that has at

least complicated your findings, if not discredit it. Did them, Yeah, well yeah, and that's you know, they had opened up their research to that kind of scientific scrutiny. They were basically saying, hey, y'all, would you please check this for us? And so that's and that's the process of science. And that's really what Jonathan and I talked about in our

previous episode about BICEP. Let's be responsible scientists, folks, And that's exactly what was going on here, which sometimes leads to disappointing outcomes, but it's better than UH being wrong and just sticking to being wrong, and and even even disproving an outcome can be fascinating and in terms of research progress moving forward. Right, So, in the case of BICEP two, we're talking about using telescopes to try and detect UH the presence of gravitational waves through its effects

on other stuff. But what about just trying to detect the presence of gravitational waves themselves, not look at how it's affecting something else, but somehow detecting their presence here on earth. So let me guess you get two things, and you put them a kilometer apart, and you watch them real close to see if they vary by the width of a thousandth of a proton very close. You actually have to get at least three things. Uh, and then you have to watch them very close with lasers.

So this was an idea that was proposed by Ray weiss Um. He suggested creating a laser interferometer system to detect any sort of distortion in spacetime. And uh, it's a really brilliant and elegant solution to a difficult problem. Yeah, and and he started working on this along with one of the other people who would become a lead on the project, Kip Thorne. Kip Thorne, by the way, good name,

good good job. Kip Thorne's parents. Anyway, So they got their start way back in five when the two of them happened to share a hotel room at a conference and wound up just staying up all night chattering about gravitational waves and feel that's not what's going to happen to me at south By Southwest, I know anyway, So so Thorn wound up pulling in Ronald Drever, who's whose original idea I think it was to use lasers for this, And the work was originally out of cal Tech because Weiss,

who was at m I T at the time, couldn't convince M I T the black holes were cool enough to study sat draw bone. Yeah, he says, by the way, that M I T has since gotten better. So LEGO is the pair of observatories that was responsible for detecting this particular gravitational wave. Have you seen a picture of one of the LEGO facilities. Yes, they're really cool. Yeah, they look like giant V or an L. Yeah, depends on your perspective. I suppose, I guess. I guess so.

I always thought it L not V shaped, But I understand entirely. Um. The so LEGO, the Laser Interferometer Gravitational Wave Observatory. Its purpose wasn't to look for gravitational waves that were responsible during or were a result oather of cosmic inflation. Uh, they're looking for things that happened after the Big Bang, things like black holes colliding or these neutron stars that are in orbit around one another. That's

sort of stuff. Those those sort of gravitational waves. The presence of gravitational waves that are actively passing through Earth, that's what these are looking for. And so they're not telescopes. So the discovery that was announced in February is though they're both involving gravitational waves, they were sort of fundamentally different discoveries between that and the one from Yes. So, uh,

some interesting stuff about LEGO. It originally went online in two thousand two UM and it was the largest project to ever be funded by the National Science Foundation at that time. They've spent over the past forty years about one point one billion dollars in pursuit of this. YEP. And like I mentioned before, there are two observing stations. One is in Louisiana and the other is in Washington.

There almost two thousand miles apart. Part I'll talk more about exactly how far they are a little bit later, but uh uh, the two stations are necessary to confirm the presence of gravitational waves. You want that same observation to be picked up by both facilities within like ten milliseconds of one another for it to be considered a potential gravitational wave. Hit right, because otherwise, you know, like a really big truck passing by could possibly set off

one of the monitors. It could be a seismic activity, could be anything that would uh jitter the system, if you will. And if one of them picks it up and the other one doesn't, then that tells you it was probably a localized event that gave a false positive at one observatory. If both of them pick it up again within ten milliseconds of each other and it's clearly the same frequency wave, we know it's not a giant

crayfish attack in the Louisiana location. That's right. It's probably we're probably not John Balaya related at that point unless they've unless they've colluded, colluding crawfish Washington, right, crawfish collusion. I gotta find your stash of though medication, because I want whatever you're on, So you don't let's talk about so I don't want the cold, that's true. Let's talk

about the the actual facility. So I think of them as being L shaped because there they are the two branches or two arms of this facility are at a ninety degree angle from one another. And maybe because Lego starts with a nail, that also a bit of priming there. Yeah, that probably probably helps. You're right, they are at ninety degree angle, but it's this giant nine degree angle with arms stretching way out into the into the fields. Yeah. So there's one that goes under a little road. Did

you see that one? Because like there's like a they built a little tunnel that the arm goes through and a road passes over it. And by road, I mean like a dirt road. I'm not talking like a highway or something. So each branch of the l each arm of the is two and a half miles or four

kilometers long, and it's actually a vacuum tube. They pump out all the air uh in the facility in order to avoid any kind of absorption, refraction or anything like that, any any interference that atmosphere could create while you're firing a laser down this tube. And they actually have a beam splitter, So they have a single laser that generates a laser beam hits a beam splitter. The beam splitter splits the beam as the name would indicate into two.

One goes down one branch, the other one goes down the other branch. Remember they're perpendicular to each other. H branch has a series of mirrors in it, so the lasers bounce off the mirrors and return back to the crux of the l and there, because they're both from the same laser, they have the same wavelength, they cancel one another out. That's where the interferometry comes in. Yes,

so they interfere with one another. They end up creating uh. Well, because they cancel out, there's no more light that's admitted through the the that area. And they have a light detector, so the light detector would detect if any laser light came through. But as long as everything is going perfectly well,

they cancel each other out. But what if somebody were to come along and shorten one of those long arms a little bit, Well, then one laser would travel a shorter distance than the other laser, and those wavelengths would be out of alignment, and then you would get some laser light coming out from that, and the light detector would pick it up and say, hey, uh, things are hinky.

So when a gravitational wave moves through. What happens is one arm will start to get longer while another arm will start to get shorter, and then they alternate because they're perpendicular to one another, and that's the way the wave propagates across the facility. That's why you have an l shape in the first place, because of that ninety degree perpendicular alignment means one side is going to always be getting shorter while the the one is getting longer

as a gravitational wave passes through. So that means that while the wave is passing through, the laser on one side is traveling a shorter distance than the laser on the other side, and that ends up creating this mismatch of wavelengths, and you get the light leaking through. The light detector picks it up and and and then you've got data to analyze and you can say, all right, we've got a hit. Let's find out if our counterparts at the other observatory also picked this up. And if

they did, then that's a potential gravitational wave. And it's really elegant approach to detecting something like this, and it's incredibly precise. So I was watching a video where one of the engineers was talking about the measurements that are made by this, and they said, when we talk about differences in distance, we're talking about the distance of ten

to the minus nineteen power meters small. So again, you take a take the number ten, take a decimal place, moveing to the left nineteen times put meter behind it. That's the distance we're talking about for uh. You know that has to be measured when one of these gravitational waves passes through, and they're passing through at a fraction of a second, so it's incredibly precise, very fast measurement that has to take place in order for even one

of the observatories to say we got a hit. But as we mentioned earlier, if only one of them has a hit, we know that that's probably a false positive. It's probably a localized event in Louisiana or possibly Washington, in which case it will make the news. In Louisiana it's old hat, but in Washington that would be unusual. Uh So, yeah, because they are so far apart by specifically it's one thousand between the two or three thousand two kilometers, that light does take a little longer to

it to one versus the other. It all depends on what what direction the gravitational wave is coming from. But there will be a delay. It's a tiny delay again, less than ten milliseconds, but it's enough of a delay that if there is that amount of time between the two and they're picking up the same frequency wave or same frequency in in this interference, then that suggests that

they found a gravitational wave. And now this kind of precision means that they had to go through a little bit of a growth period before they could really get these things working. Yeah, so here's here's the bad news they had to give. The facility came online in two thousand two, by it was clear that the instrumentation they were using was not going to be precise enough to pick up gravitational waves. It didn't matter how long they

left it on, it was just not precise enough. And they had to go back to the drawing board and say, we're gonna need to upgrade these facilities in order for them to be capable of detecting this. If in fact, gravitational waves are a thing, then we're going and we know that they are, but in order for us to

detect them, we're gonna have to get more precise. So in twousen LIGO goes offline and there was an international collaboration that took five years of work to overhaul and upgrade LIGO until they got advanced LEGO or a. Yeah. The observatories came back online in September two thou fifteen, and literally days after turning on, they detected a gravitational wave. So think about this for a second. The gravitational wave they detected was from a pair of black holes colliding.

That pair of black holes collided one point three billion years ago, and that means that the black holes were by definition one point three billion light years away from Earth, because again, gravitational waves travel at speed of light. So one point three billion years ago, one point three billion light years away, two black holes collided, and the facility came online just days earlier at you know, on Earth

one point three billion years later. To catch it. That's like the biggest dartboard you can imagine with the tiniest bull's eye, and you are miles away and you just happened to throw it perfectly well, so that catches the air and flies over and hits that bull's eye. Now granted, that is pretty amazing, but it's also it's a big universe.

Is a big universe, and people have said that things like the black holes colliding events of that nature happened in the universe on the order of about every fifteen minutes, but it all depends on when and where they happened, right like if it happened a billion years ago, but it's four billion light years away, it will be three billion more years before those gravitational waves make it to Earth. So because the universe is big, yes, these things happen

all the time, but they don't hit Earth all the time. Yeah, it was still pretty cool. Yeah, it's really really cool, so cool that I remember on the day it was announced one of the people working at Lego said, Yeah, at first we thought that they might have been testing the system again, and then we checked and no one was testing the system and we were like, whoa, it works. And so that was just one of those like great

fortuitous moments um and yeah, it was very exciting. Of course, they wanted to take time to confirm it, to validate the information, which is why we did not hear about it till February eleven, twenty sixteen, so it was some time later before we got a chance to find out what the big discovery was. You know. One of the cool things to me about this, uh, this observation, they called it a chirp. Yeah, the thing that they detected

of the gravitational waves. And because it's a wave with a certain number of number of oscillations per second represented as hurts, you can actually represent this chirp as sound, which people have done there. I watched one YouTube video that was a compilation of different scientists and people who were involved with the project doing doing little chirps, doing their little gravitational wave of chirps with their mouths and

devices and stuff. I'm so glad I didn't make one of those videos, would be so tempted just to do the whole stupid Rick Roll thing. So the Louisiana Observatory detected that gravitational wave first, and seven milliseconds later the Washington Observatory detected it. So that's what when they were able to say, yes, this does appear to be a

gravitational wave. And they used triangulation to determine where did this come from, and they determined that it was coming from the Southern hemisphere skies um and that's what led them to the conclusion of hey, you know, we this this is working. We understand where this is coming from and even what's causing it, which was really cool, But that wasn't all they were able to tell about it from the data collected. In fact, they were able to look at the data they had and say what they

think happened to cause these gravitational waves? Yeah, yeah, Like so, let's it's hard to explain how huge a moment this is. It's it's very difficult to kind of put that into words. But keep in mind that black holes, while we understand they are a thing, it's not something that we directly observe, right, But you can't see a black hole, because that's rather the point. Yeah, they really, you really can't. You can see the effects off of them and nothing escapes from them.

So yeah, you can. You can see how gas clouds behave in vicinity of you know, like in the Kessel run, you see gravitational lensing. Yes, you can see gravitational lensing.

But you know, this is about as strong evidence for the existence of black holes as you can get without sending Matthew McConaughey through one um, and certainly the strongest evidence for binary black holes where you have to colliding with one another, and the data picked up matched the calculations that that people had made based upon the knowledge of general relativity in physics about what would happen with these two black holes so well that it was phenomenal.

So reality and math were actually agreeing with one another, which is fantastic. They determined the black holes in question were pretty pretty big, not like super massive black holes. We're not talking about the kind that would be at the center of a galaxy or anything. But one had twenty nine times the mass of our Sun and the other thirty six times the Sun's mass, and right before they collided, they were circling each other two and fifty

times a second UM. During the actual collision, which took place over about a fifth of a second, they blogged together and then coalesced into like a smooth sphere in a process that's called ring down and ring down and it's and it's this process in which three solar masses worth of energy was vaporized that that caused the gravitational waves that we observed um. The resulting black hole, by the way, is therefore only sixty two times the mass

of the Sun, being that three masses just went. Yeah, and when you think about energy equals mass times the speed of light squared, and you think three solar masses vaporized, that's that's an unimaginably huge amount of energy, right, Like it's so enormous that I can't even begin to think about it, so I won't. Yeah, yeah that but but yeah, if you're wondering how something that was that far away

propagated all the way to Earth, that's why. So again remarkable that this facility even picked up the signal in the first place, considering that, you know, it all has to be timed out where this thing that happened one point three billion years ago, one point three billion light years away. Uh, just the observatory coming online when it did, like all of that is pretty phenomenal stuff. Yeah, and they almost didn't do the engineering run during which the

signal was found. Uh, just three days prior, the Livingstone antenna was getting some radio interference and White actually recommended that they put off the run. But his colleagues they're were like, Nah, let's let's go ahead. We think it's ready, so don't worry about it. The nice thing is that we know eventually this would have worked anyway, but it was still just just one of those cool stories about how much came into alignment to allow it to happen

so early. When it came back online, it's a great story for science. Well. One of the things that I have definitely heard reported from some of the people involved in the project is that the signal was much stronger than they expected it to be. Like they they were able to see the signal clearly in the data with the naked eye just looking at the data. They're like, oh,

there it is. When what they thought they we're gonna have to do was like run a you know, computational analysis across all the data and compare it to uh to random noise generated as a sort of cross reference, and see if it maybe was a gravitational wave. But no, it was just obvious, which is amazing. And so this is kind of wrapping up our initial discussion about gravitational waves. In our next episode, we're gonna talk a little bit more about the specifics of what Lego found. I'm gonna

talk a little bit about some angular momentum. In that episode, we'll also talk about what does this mean and the rise of a new type of astronomy, gravitational astronomy, which is literally in its infancy right now. Uh and what could this possibly mean for the future? That will be

in our next episode. Guys, if you have suggestions for future episodes of Forward Thinking, I recommend you write us and tell us because if you've been putting messages and bottles and throwing them in the ocean one, you're littering. Stop it and they're not getting to us. So right, Atlanta is landlocked? Yeah, yeah, you know, be careful about sushi in Atlanta. That's all I'm saying. Now, send us

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