Daniel and Kelly’s Extraordinary Universe - What are Gravitational Waves?

Episode Date: October 9, 2018

What does it mean for gravity to make waves? How do we see them? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

This is an I-Heart podcast. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the TWA terminal. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System

On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want or gone.

Now, hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast and the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about how to be a better you. When you think about emotion regulation, you're not going to choose an adaptive strategy,

which is more effortful to use. unless you think there's a good outcome. Avoidance is easier. Ignoring is easier. Denials is easier. Complex problem solving. Takes effort. Listen to the psychology podcast on the Iheart radio app,

Apple Podcasts, or wherever you get your podcasts. Okay, Daniel, is it possible for Einstein, the famous scientist, to be wrong? Well, I got a lot of crackpots in my inbox every week claiming to have proven Einstein. Einstein wrong because it's every physicist's number one fantasy to prove that the most famous scientists of all time could have made a mistake. Well, I have the proof here for you. I heard that Einstein, he was right about a lot of things, but I heard that he predicted that we would never see gravitational waves.

That's right. And then scientists actually found these crazy little features of the universe. So he was wrong, right? I mean, technically he was wrong in that he predicted that physicists couldn't prove him right. Yeah, it's a small victory. but technically we've proven Einstein wrong. We'll take it. We'll take it.

Welcome to our podcast, Daniel and Jorge Explain the Universe. Now, I am a cartoonist. And I'm a particle physicist. I draw comics called PhD Comics online. And I do research at a large Hedron Collider, smashing protons together to try to figure out what the universe is made out of and explain it to you. Yeah, we just like talking about this crazy stuff that our universe is made of and how it works.

We basically think of what could people out there be interested in? What kind of questions does an everyday person have about the universe? And we thought, let's dig into that and explain it. Today on the program, we're going to talk about gravitational waves. What is a gravitational wave? That's today's topic. What are they? How wavy are they? And will they make you gravitationally seasick? It's a grave topic today. It's a grave. Grave topic. This topic, we hope, won't put you in your grave.

That's right. It'll make you feel lighter, actually. Even though it's a pretty heavy topic. You probably know what gravity is. You probably know what a wave is. But we went out in the street and we asked people, do they know what a gravitation? wave is. Here's what they had to say. A wave of gravity, kind of like how it acts on people. The only thing that I might take a guess is gravitational waves

is because something that's reflected from the sun? No, I've heard of gravity, not gravitational waves. I'm not sure, yeah. Okay, so most people have heard of the word gravity. That was encouraging. That's good. That's encouraging from your general sense of what do people out there know? Yeah, yeah, you know.

like it's not, well, it's kind of an interesting concept, right? Because gravitational waves, it's like two things everybody knows about, gravity and waves. And it's like you put them together, suddenly it's this whole new thing, nobody knows about. That's right. And frankly, it surprised me how little people knew about it. Because some people had heard of the topic, but knew almost nothing. Some people really had no idea what it was. But for me, as a physicist, this is something that made a huge splash in the physics community. It made enormous waves, jokes aside.

when it was discovered a few years ago. I mean, it's the kind of thing where they discovered it and almost immediately won the Nobel Prize for it. That's a big deal. Yeah, but I guess the truth is that I had never heard about it until the big discovery was announced, you know? And I'm pretty sort of plugged into research and physicist. But no, I had no idea what these things were

until I started hearing from physicists like, hey, we think there's a big discovery about to be announced. That's right. There were rumors bubbling around for a while. But I don't think you're unusual. I think before the discovery, nobody outside of physics had really heard of gravitational waves. And even most people inside physics thought it was kind of a crazy backwater subfield that might not ever amount to anything. But once it happened, there's this huge splash and publicity and everything.

You'd think it's spread around the world and everybody would remember. But I guess it's faded. Maybe if we'd done this a couple of years ago, just after the announcement, people might know more or remember more or at least be better at pretending they knew something about it, right? Right. Or maybe it's just kind of a reflection of how we're all trapped in our little bubbles these days, you know? Like what feels like a huge deal that it's all over the media to us, maybe somebody who lives in another media bubble has, it doesn't make it to them, you know? Yeah. Yeah, maybe. Well, one of the fun things about these interviews is hearing people trying to figure it out as they're talking to me. You know, like, maybe it has something to do with the sun or like it has waves on people or something. I think that's pretty insightful for some psychologist. to dig into. Right. And it's been a big deal

in the physics community for a while. I mean, the project that discovered these gravitational weights a few years ago,

LIGO, that's been going on for years and years. It's like one of the most expensive physics experiments ever, right? It's been going on

for a long time. It's not one of the most expensive. It's only $600-something million dollars. Oh my God. I can't even say that phrase without laughing.

To a particle physics. I know. From the point of view like the LHC, which is 10 billion, And yeah, this is a pretty cheap experiment. But the amazing thing is that it's been going on for decades before it got results. I mean, they've been working on this since the 70s and 80s,

and they've been getting funding with no discovery for decades. That's the kind of crazy blue sky research that I think is wonderful, but is happening less and less these days. Well, let's break it down. What is a gravitational wave? Right. So a gravitational wave. Simply put, a gravitational wave is a ripple in space, right?

Space itself is not emptiness. It's not the backdrop of the universe. It's not nothing. It's a physical, dynamical thing. It's like we're fish swimming through water, right? And space is our water. And so it turns out because space can do things like bend and expand, it can also ripple. And so a gravitational wave is a ripple in space itself.

So like if you were a fish your whole life and you were just moving through water, you wouldn't think of the water as a thing. It would just be the thing you're moving around in it, right? That's right. you might not even notice that it's there unless it did something or had some effect on you, right? And so if you're a fish, you notice, oh, look, there are currents and I can surf those or whatever. And so we're starting to notice the space is doing some stuff. And that's what makes us pay attention to it.

Okay. So gravitational wave is a ripple of the space itself. Like the space itself we're in actually sort of ripples. Yeah. And I think people might have an easier time understanding ripples if they start first by thinking about other things that space can do, which are similar, like space bending. So space is three dimensions. Yeah, that we know of, right? That we know of, yeah.

Down, forward, backward, left, right. But it's hard to imagine space bending in 3D, so it's easier to think of it in two dimensions. So a typical example is think of like a big rubber sheet. That's space. Well, space can be bent when you have big, heavy objects sitting on it. Like if you put a big bowling ball onto a rubber sheet, it's going to distort it.

And then if you, for example, if you roll a marble across that sheet, it's not going to anymore move in a straight line. It's going to move like in an order. orbit, or if you've ever spun a coin down one of those crazy parabolic things in a museum and Sun had seen it do crazy orbits, space gets bent by mass, and that's what makes things go around the sun, for example. So space is not like a flat, stiff sheet. It's like this kind of wobbly kind of thing that we're rolling along in. That's right. We're rolling along it. We're moving in what seems like the most natural path, the straightest line for us, unless you get pushed in some direction. But if there's a big heavy thing near us, like the Earth or the Sun, pretty big, massive stuff in the universe, then it bends that space and affects sort of the natural straight line we would travel in.

And so people can practice thinking about space bending by understanding how big heavy masses can distort space affecting the way that we move through it. And the subtle bit there is in the rubber sheet analogy, the two-dimensional rubber sheet is bending into the third dimension, right? which doesn't exist in the 2D rubber sheet universe. But in the full 3D example, in the real universe that we're in, our space is not bending in some hidden higher fourth dimensional universe. The bending is intrinsic. It's the relationship of objects in that space. If you want to ask like, what's the shortest distance through space for these two points?

That's affected by this bending of the space between them. Oh, so it's kind of like the relationship between things in space is what's. changing, what's getting distorted. Exactly, the relationship between things in space. And when I first started thinking about this, like space as a thing, even as a physicist, it's pretty hard to think about because you imagine space as being defined by distances, or as you say, like, the relationship between things. And so I always wondered, like, how could you even tell if space is bending?

Because wouldn't your rulers bend also? Like, don't you need some, like, absolute external yardstick to notice if space is bending? But you would notice it, wouldn't you? Like if I'm near a distorted space and I take my ruler and I point it one way, I would measure something differently than if I pointed it another way. Yeah, exactly right. And that depends a little bit on how your ruler is built, right? If your ruler is built out of molecules, like most rulers, and those molecules have a distance between them that's fixed by like their, you know, the forces between them, like, you know, a standard wooden ruler is held together by chemical bonds, then those bonds are going to be stronger than like any space stretching. And so a ruler like that is not going to be affected by space getting stretched.

And so it would certainly notice. But say, for example, your ruler was like a bunch of equidistant pebbles floating in space, right? Then if space stretched, you wouldn't even notice because the distances between those, the pebbles would grow and shrink as well. And you would have no comparison. Oh, you mean like if you measure distances kind of like they do in my home country of Panama. It's not like you look it up in a GPS map. It's more like, okay, you go down this street and then you make a right. at the McDonald's, and you make a left at the gas station, and that's how you get to my house,

then if, if, like, the terrain change, I wouldn't notice a difference because I would still use these landmarks. Still get to McDonald's. Exactly. You still take a right. Yeah. Yeah. So if there's, like, an earthquake and suddenly McDonald's is much further away, it's still like, you know, it's one McDonald's away still, right? Well, this is a perfect spot to take a break. We'll be right back. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed.

There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal, glass. The injured were being loaded into ambulances. just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In Season 2, we're turning our focus to a threat that hides in plain sight.

That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her.

Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him?

Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hola, it's Honey German, and my podcast, Grasasas Come Again, is back. This season we're going even deeper into the world of music and entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition.

I haven't audition in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We've got some of the biggest actors, musicians, content creators, and culture shifters sharing their real stories of failure and success. You were destined to be a start. We talk all about.

what's viral and trending with a little bit of chisement, a lot of laughs, and those amazing vivras you've come to expect. And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community. You feel like you get a little whitewash because you have to do the code switching? I won't say whitewash because at the end of the day, you know, I'm me. But the whole pretending and code, you know, it takes a toll on you. Listen to the new season of Grasasas Come Again as part of my culture podcast network on the IHart Radio app, Apple Podcast, or wherever you get your podcast. So space is this squishy thing that we're living in.

It's not like a big vacuum or an empty warehouse. It's like this squishy thing and it's going to squish by things that are heavy and that can affect how far things are apart from each other. So now a ripple is like, what is that then? Like a ripple in water? Is it similar to like a ripple? Like if your fish? is a ripple gravitation wave

like a ripple in the water you know like if there's an explosion underwater we would feel that sort of shock wave that's exactly what it is yeah and so if you have two really heavy objects for example spinning around each other or one really massive object that's accelerated the gravitational field from that object

is going to change really quickly right so imagine a static object is a gravitational field around it if that object accelerates or moves its velocity is changed really quickly then the gravitational field itself is going to change and the wiggle in the field caused by the acceleration of that object

is a ripple. It's going to travel through space outward from that object. So imagine you take like a rock it has a gravitational field. A rock is going to be bending space around it and then if you move that rock something far away is not going to notice instantaneously that you move the rock.

It can't tell that the gravity has changed yet because the information about the rock moving travels at the speed of light. So even gravity can only move at the speed of light. That's right. Everything in the universe that carries information

can only move at the speed of light or slower. And so, for example, say the sun disappeared magically. The Earth wouldn't notice for eight minutes. What? Because that's how long it takes

for light from the sun and for the gravity from the sun to reach us. So the path of the Earth wouldn't be affected for eight minutes. So there'd be eight minutes where there was no sun, but the Earth would just keep going

like, hey, we wouldn't see it gone either, right? because the light would also take eight minutes to get here. That's right. The sun could have disappeared five minutes ago and we would have no idea. Don't rush outside and look at the sun, everybody. Please don't. No, I'm scared, Daniel. Anyway, in that scenario, there's nothing you can do in that scenario, so there's no point in preparing for it. But the point is that gravitational information moves through space the same speed, everything else does.

And so if something is changing really quickly, then that increasing gravity, decreasing gravity would sort of travel, would take a while to get to me. and I would see that as kind of a wave, like a ripple. Yeah, exactly. Imagine somebody's turning the sun on and off. It exists, it disappears. It exists, it disappears. Then the gravitational field of the sun, this bending of space, is going to disappear and then snap back and disappear and snap back.

And what we would see it on Earth is gravity turning on and off and on and off. And those would be enormous ripples in a gravitational field, yeah. Wow. Well, I think what's cool is that, you know, everyone talks about it like it has to be like, black holes or something huge and massive, but it's really like everything generates gravitational waves, right? Like you and I, if I move my arms back and forth, I'm generating gravitational waves. That's right. And you happen to be a very magnetic person or a gravitational person, so I sense those waves from you. I'm glad you didn't say heavy. Thank you.

I know. I was about to say that and I was trying to steer clear of it. Yeah, you're right. Everything that has mass, bend space, and anything that has mass and is accelerated will be generating gravitational waves. But the thing for people to remember is that gravity is super-duper crazy, ridiculously weak, which is why, for example, if you're sitting next to somebody in a train, you don't feel a literal gravitational force between you. There is one there, but you can't even sense it because it's so tiny compared to the gravitational force of you and the earth.

No matter how attractive that person is. That's right. You might be feeling other forces, and feel free to act on that. or not. Or not. Yeah. Up to you. There's no physics advice about whether or not to approach people on a train. But your point is correct. Everything is generating gravitational waves that has mass and is accelerating. Right. But they're so weak. Yeah. You need something really, really huge in order to be able to detect them.

Okay. Well, let's talk about how we even came out with this idea of a gravitational wave, right? Who sits around thinking, hey, I wonder if ripple if gravity in space time itself can generate waves? Well, your first guess would probably be right in that case because the first person to think about that was Albert Einstein, right? Everybody's go-to scientist. In this case, it's exactly right. He came up with this theory of general relativity, and the core idea in that theory is that gravity is not a force,

but a bending of space. And so a very natural consequence of his theory was that if things accelerate, then it would make these ripples in the bending of space, and those ripples he called gravitational waves. Oh, I see. It's like once you come up with the idea that space can bend and that also this information about space bending can travel faster than light,

then you're naturally left with the idea that you can have these waves traveling through space for gravity. Yeah, exactly. But a funny wrinkle in the story, or ripple in the story, if you like, is that Einstein, he thought about these things as sort of a theoretical possibility or an abstract idea. but he, I think he wrote in his paper, he's like, he said, but we could never discover these because they're too small. Even Einstein who predicted these things thought it would be impossible for us to ever detect them, which is like even more kudos to the experimentalists for proving Einstein wrong by proving him right. Wow. So even Einstein didn't think that it

would be possible to measure these, but they've done it. They did it a couple of years ago. Yeah. And you know, there's one way in which I personally agreed with Einstein because I remember when I was choosing where to go for graduate school. I was visiting various institutions and thinking about what physics they were doing and I went to Caltech and Caltech is one of the leading institutions on LIGO and I actually got

to talk to one of the leading scientists on it at the time and he was telling me about this project and I thought, wow, this sounds cool but really hard and basically impossible and I would be crazy to sign up to do a PhD on this. I thought they're never going to see these things. It's impossible and ridiculous.

More power to you, but I'm going to go do particle physics. On that note, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the team. A TWA terminal. Apparently, the explosion actually impelled metal glass.

The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and either. and harder to stop. Listen to the new season of Law and Order Criminal Justice System

on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone.

Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet.

So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK. Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hola, it's HoneyGerman. And my podcast, Grasasas Come Again, is back. This season, we're going even deeper into the world of music and entertainment

with raw and honest conversations with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't audition in, like, over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah.

We've got some of the biggest actors, musicians, content creators, and culture shifters, sharing their real stories of failure and success. I feel like this is my destiny. You were destined to be a start. We talk all about what's viral and trending with a little bit of chisement, a lot of laughs, and those amazing Vibras you've come to expect.

And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community. You feel like you get a little whitewash because you have to do the code switching? I won't say whitewash because at the end of the day, you know what I'm me? Yeah. But the whole,

pretending and, you know, it takes a toll on you. Listen to the new season of Grasasas Come Again as part of My Cultura Podcast Network on the IHartRadio app, Apple Podcasts, or wherever you get your podcast. The skill of the problem is insane, right? Like, it's, first of all, you need something momentous happening, like two black holes spinning around each other so fast. And I'm just about to. like crash together, right? Yeah, really, really massive objects and you need a lot of acceleration also.

As you say, for example, black holes smashing into each other does that. And the reason is that the very last moment before the black holes collide into each other, they're moving super fast. It's a huge acceleration there. Oh, because, you know, we think of black holes crashing like they're traveling the straight line and they crash into each other, but they don't, right? They actually kind of get close to each other and then they start circling each other and then that circling gets smaller and smaller and smaller and smaller. Yeah, exactly. They spin around each other a little bit.

Unless you build like a black hole collider to shoot them exactly at each other. And, you know, anybody out there who knows how to do that, give me a call. Yeah. But if two natural black holes that approach each other are going to already have some relative angular momentum, so they're going to keep that relative spin from each other, so they're going to keep that. And then they're just going to spin around each other as it gets closer and closer to have the same angular momentum that you're going to have to go faster and faster. Kind of like when you flush the toilet, you know, two things floating there. spinning around each other

and then as they get closer and closer they start spinning really really fast yes exactly the dark matter in your toilet from the black hole yeah exactly it spins around each other

I was going to say more like an ice skater who spins around faster and faster as she pulls her arms in but yes also dark matter in your toilet does the same thing yeah and then right before it flushes down it's spinning so fast that's when these

it generates massive gravitational waves right that's the idea that's right So Jorge's takeaway from this topic is every time you flush the toilet, you're generating gravitational waves. Which is technically true. Which is technically accurately true. Yes. Yes. Yes. And you have a physicist now on record saying that. But in the case of the cosmic toilet, you know, when black holes actually swish around each other and flesh themselves away, what happens is you get these ripples. And when the ripple passes through Earth, it squeezes the space in one direction and stretches it in the other. That's the effect of the ripple on Earth.

So if we want to see it, we have to have a very accurate ruler pointing in two directions, one, 90 degrees from the other. So we can see a squeeze in one way and a stretch in the other direction at the same time. So the direction of the wave tells you where it was coming from also. And you want to calibrate yourself by having measurements in the direction of the wave and 90 degrees. Also, because you don't know which direction a wave is going to come from, you want to make sure to be sensitive to it no matter where it comes. So you have two basically really careful rulers that are 90 degrees or arranged from each other so you can be sensitive to any direction.

But it's crazy because even though these are generated by two colliding black holes, by the time they get to us, these waves are like really faint, right? Yeah, they're really are tiny. I mean, Einstein had a good point. In order to see these things, you have to see space shrink by one factor in 10 to the 20, right? That's 10 with 20 zeros after it. It's like if you had a meter stick that was 10 to the 20 meters long, you would have to see it shrink by one meter. Yeah, exactly.

Yeah, or if you wanted to see something shrink by like a millimeter, you'd have to have a yardstick that's like, you know, 10, 6 trillion meters long or something crazy. It's really ridiculous. It's like the size of our solar system, right? Yeah, I think so. And so you can imagine not only is it really hard to see things that are small, but other things are affecting you, right? Not that anything else is shaping space that same way.

But if you have a ruler, how do you even know how long it is to 10 to the 20, right? To one part in 10 to the 20. How do you detect when it's wiggling? Like if you just heat up your ruler, it's going to get a little longer. If you cool down your ruler, it's going to get a little shorter. So the experimental trouble of seeing something so tiny is really, really, it's really difficult. And it's really an amazing coup de grace that they pulled it off. So it's like if I was standing on one end of the solar system and you were standing on the other side of the solar system, it would be like asking like, hey, Daniel, did you feel the space between us shrink by one millimeter?

Exactly. That's crazy. It's pretty crazy. And so in order to do it, they had to come up with some pretty crazy technology. The way they do it is really awesome and beautiful. I mean, there's fascinating theoretical stuff. But the experimental side of it, I love also because they had to come up with new techniques that nobody had ever used before. So this is the LIGO project, right?

L-I-G-O? Yeah, that's right. LIGO stands for laser interferometric, I think, gravitational observatory. Okay. LIGO. Not to be confused with LEGO. That's right. Lego's almost as expensive as LIGO.

But the way they do it is they have these two rulers that are, you know, four kilometers long each, and they shoot a beam of laser light all the way down this tunnel, and then it bounces off a mirror and comes back. and they do that simultaneously along both legs and then when the lasers come back they can tell how far the light went by comparing how many wiggles it's made it's kind of like a relay race right

like you send a laser beam out and then you measure how long it takes for it to come back and that's how you know how far it went yeah but you don't need to measure the time because lasers are light and light has wave-like properties and so it wiggles so if you send out two beams of laser and then they at the same direction

and they bounce off mirrors and come back, they're going to be wiggling all the way there and wiggling all the way back. And when they come back, they should be the same place in their wiggle, right, either up or down. And if they're in the same place in their wiggle, they'll add up together.

If they're at opposite places in their wiggle, like one of them went a little bit further, and now instead of being in the up wiggle, it's at the down wiggle, then those two will add up to be zero. Destructive interference. And so that's the interferometer part of the experiment,

send out these two pulses of lasers, and when they come back, they see, are they interfering positively by adding up on top of each other or interfering negatively by canceling each other out? If they're interfering negatively, it means one of them wiggles a little bit longer than the other one, or a little bit shorter, and now they're out of sync. I see. So it's not like you're measuring whether the distance in one direction change, you're measuring whether it change relative to the other direction. Exactly. And that's what these ways do. They shrink space in one direction and stretch it in the other direction. Exactly. And so that's what you're looking for.

And they actually have multiple observatories. They have one in Louisiana and one in Washington State. And they're finishing one or just finished one in Italy and they're building other ones around the world. And the idea, and they're all pointed in different directions and there are different locations. So you can use those multiple telescopes to tell you like, is it real? Or is it just like a semi-truck driving over it, which is shaking all of my mirrors?

And you can also do it to tell like where did it come from? Because if it landed in Washington before it landed in Louisiana, then you can tell which direction it came from. You can use it to sort of triangulate. It's interesting how the word telescope changes, right? Because of physicists, right? Like people think of a telescope as this tube that you look through to tell how far ships are away from you or something

or how far land is. That's a telescope. And nowadays, telescope in science way means, you know, it could mean a giant antenna or it could mean like an array of antennas or it could be like these crazy, long laser tunnels spread all over the world. Like, you call that a telescope. Yeah, well, I think telescope, I'm not a linguist, but I think telescope essentially means seeing far away.

And so you can just generalize it to mean we don't have to see only with light, right? We can see with other things. And so you're right. And I think that's an awesome use of the word telescope, because as we invent new kinds of technologies and new kinds of telescopes, it gives us other ways to look out into the universe. And, you know, we're in this tiny little dot in a little dot, corner of the universe, desperately drinking in the information that the universe is sending to us.

It's wonderful to imagine, can we have another way to listen to the universe? Can we have another way to get information about where we are and what's going on around us? Well, that's what people say it's so significant about the discovery of gravitational waves, is that it gives us another way to listen to the universe, right? That's what people say. It's like a new way of listening to the universe. Yeah, that's right. And it is amazing and dramatic. A couple of quibbles, though. Sometimes Sometimes people say it's the first time we have another way to listen to the universe, right? They say, forever we've been doing astronomy using only light, and now we have a second method. It's not exactly true because we also have particles.

For example, we've been using neutrinos to look at the universe, and we've been detecting neutrinos for a while now. So it is true that we're adding to our tool belt by adding gravitational waves, and it's hugely important and fascinating. But it's not the first time we have a new tool in our belt. So primarily before, the only way we even know about the rest of the universe or what's going on is by the light or the particles that come to us. Yeah, the photons from stars and from other galaxies. Yeah, it's all been photons. Like the radio waves, those are all photons and light, different kinds of light. But now, in addition to particles and light, we have this other way of like knowing what's going on elsewhere in the universe, which is these gravitational waves. And it's really important not just because it's cool, new shiny tool, which is fun.

but because gravitational waves can do things that particles can't, right? Gravitational waves are not moving through space, so they're not blocked the way things move through space are, right? There's no dust cloud that can block a gravitational wave. They don't get like attenuated if they hit a big black hole or something? Well, they can be attenuated the further way you are, right? Like everything else, they spread out through space and they get weaker and weaker. But they can't be blocked by matter.

I mean, they can get, if you have another gravitational wave, they can get reflected or distorted or something. But it penetrates through things which are otherwise invisible to us and can send us messages from inside things that otherwise would be opaque to us. And so it's a really powerful, fascinating new tool. It really is like we're opening up a new kind of eye to the universe for the first time. One of the other crazy things about gravitational waves is that we had no idea how often they came. One tricky thing is, can you see them at all?

The second tricky thing was, are there any anyway? It could have been that we're really. good at seeing them. We developed this amazing technology. We're super sensitive to these tiny little effects, but they only come once every 100 years. You mean like the kinds of events that would generate them in a large enough way for us to detect may not be happening as often as we think. Like these black holes crashing into each other or these neutron stars flushing down the toilet. Maybe these things were rare, right? Yeah, we didn't know, right? But the first time they turned on the experiment with their new powerful capability, they've been incrementally

improving it for decades. But when they first got to the place where they thought, okay, now we really think we can see them, they saw one within like a day of the first time they turned it on. It was incredible. And now they've been seeing many, many, many. They have like a huge pile of these things they've been studying. And so that's really exciting because it could have been that you turned on this new telescope and the universe was just really quiet and there was nothing, it didn't really have anything to say. But it turns out it's got a lot to say and these things happen more often than people hoped. And so now we can learn more about like things like black holes crashing, right? And neutron stars crashing and what happens in those like extreme moments

of physics? Yeah. Yeah, exactly. So I think one of the really exciting things is that we have this new eye on the universe, this new way to look at the universe. And in addition, there's cool stuff to see. Right. So one of the cool things they saw recently was not just two black holes colliding, but two neutron stars colliding. And the fascinating thing about that is that they saw it through the gravitational waves, and at the same time, they saw through telescopes using normal light. So they could see these two things happening

through two kinds of vision overlaid on top of each other. That was really pretty awesome. Yeah, I like the way they always describe this project, which is very poetic, I feel like it's like they always say, imagine if you're deaf your whole life. I mean, you could look around you,

but you couldn't hear anything, and then all of a sudden, somebody gives you the ability to hear stuff. And so now you not only can you see stuff with light, but you can also kind of hear them through this whole other channel. Yeah, there's some poetry there. Sometimes I think they take it a little too far because in science communication articles about this,

they often describe this as listening to the universe and you can hear the chirp. I think that gives people the impression that gravitational waves are sound or that colliding black holes make a sound. Remember that space is quiet. Sound can't go through space because there's no air.

So these are gravitational waves, and you can take the frequency of those waves and transform it into sound waves and listen to it. The way you can take the frequency of anything and transform it into sound waves. Like people took the Higgs boson events and transformed them into sound waves, and you're like listening to the Higgs boson.

I don't really think you're listening to the Higgs boson, so you're not really listening to the universe. But poetically, I agree. It's another way to get information from the universe. Yeah, it totally works as an analogy, but I think some people think it's literal and I just want to make the point that it's not literally listening to the universe

these are gravitational waves not sound waves although they kind of propagate in a similar way right well in the same way that waves do propagate but you know water waves are compression waves through a medium and gravitational waves are ripples in space and so it's a little bit different but

the analogy is very very useful as long as you remember it's an analogy don't stick your ear into space and expect to hear gravitational waves. Not a good idea. Yeah, I know. It's like, it's very poetic. It's like all of a sudden you can hear and suddenly you're hearing all these toilet flushings across the cosmos. It's very poetic. Yeah, exactly. Listen to the universe flushing away its waste. Well, on that note, thank you very much for listening. I hope you guys enjoyed that discussion.

It's a pretty heavy topic and I hope we handled it with gravitas. Yeah, I hope you didn't get gravitationally seasick. All right. Well, thank you very much. Have a great day, guys. Do you have a question you wish we would cover? Send it to us. We'd love to hear from you. You can find us on Facebook, Twitter, and Instagram at Daniel and Jorge, one word, or email us to Feedback at Danielandhorpe.com.

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