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

• 0:04
  Speaker 1: Okay, Daniel, is it possible for Einstein the famous scientists
• 0:09
  Speaker 1: to be wrong. Well, I got a lot of crackpots
• 0:12
  Speaker 1: in my inbox every week claiming have proven Einstein wrong,
• 0:15
  Speaker 1: because it's every physicists number one fantasy to prove that
• 0:19
  Speaker 1: the most famous scientists of all time could have made
• 0:21
  Speaker 1: a mistake. Well, I have to prove here for you.
• 0:24
  Speaker 1: I heard that Einstein, he was right about a lot
• 0:26
  Speaker 1: of things. But I heard that he predicted that we
• 0:27
  Speaker 1: would never see gravitational waves. That's right, and then scientists
• 0:32
  Speaker 1: actually found these crazy little features of the universe. So
• 0:36
  Speaker 1: so he was wrong, right, I mean, technically he uh
• 0:40
  Speaker 1: was wrong in that he predicted that physicists couldn't prove
• 0:43
  Speaker 1: him right. Yeah, it's a small victory, but technically we've
• 0:46
  Speaker 1: proven Einstein wrong. We'll take it. We'll take it. Hi
• 1:00
  Speaker 1: am Jorhe and I'm Daniel. Welcome to our podcast. Daniel
• 1:04
  Speaker 1: and Jorge explained the Universe. Now. I am a cartoonist
• 1:07
  Speaker 1: and I'm a particle physicist. I draw comics called PhD
• 1:11
  Speaker 1: comics online, and I do research at a large hadron collider,
• 1:15
  Speaker 1: smashing protons together to try to figure out what the
• 1:17
  Speaker 1: universe is. Made out of ent explain it to you. Yeah,
• 1:20
  Speaker 1: we just like talking about this crazy stuff that our
• 1:23
  Speaker 1: universe is made of and how it works. We basically
• 1:25
  Speaker 1: think of what could people out there be be interested in?
• 1:28
  Speaker 1: What kind of questions does that everyday person have about
• 1:31
  Speaker 1: the universe, And we thought, let's dig into that and
• 1:33
  Speaker 1: explain it to be On the program, We're going to
• 1:36
  Speaker 1: talk about gravitational waves. What is a gravitational wave? That's
• 1:43
  Speaker 1: today's topic. What are they? How wavy are they? And
• 1:46
  Speaker 1: will they make you gravitationally seasick? It's a grave topic.
• 1:51
  Speaker 1: It's a grave to this topic we hope will put
• 1:54
  Speaker 1: you in your grave. That's right, It will make you
• 1:57
  Speaker 1: feel lighter. Actually, even though it's a pretty heavy topic.
• 2:02
  Speaker 1: Don't don't you probably know what gravity is. You probably
• 2:09
  Speaker 1: know the wave is. But we went out in the
• 2:11
  Speaker 1: street and we asked people do they know what a
• 2:13
  Speaker 1: gravitational wave is. Here's what they had to say, A
• 2:17
  Speaker 1: wave of gravity kind of like how it acts on people.
• 2:20
  Speaker 1: The only thing that I might take a guess is
• 2:23
  Speaker 1: gravitational ways is because something that's reflected from the sun.
• 2:27
  Speaker 1: Uh No, I've heard of gravity, not gravitational waves. I'm
• 2:31
  Speaker 1: not sure. Yeah, okay, so most people have heard of
• 2:34
  Speaker 1: the word gravity. That was encouraging. That's good. That's encouraging
• 2:39
  Speaker 1: from your just like a general sense of what do
• 2:40
  Speaker 1: people out there know? Yeah? Yeah, you know, like like
• 2:44
  Speaker 1: it's not what It's kind of an interesting concept because
• 2:47
  Speaker 1: it's gravitational ways. It's like two things everybody knows about
• 2:50
  Speaker 1: gravity and waves, and it's like you put them together,
• 2:54
  Speaker 1: suddenly it's this whole new thing nobody knows about. That's right.
• 2:57
  Speaker 1: And frankly, it surprised me how a little people knew
• 3:00
  Speaker 1: about it, because some people had heard of the topic
• 3:02
  Speaker 1: but knew almost nothing. Some people really had no idea
• 3:05
  Speaker 1: what it was. But for me as a physicist, this
• 3:07
  Speaker 1: is something that made a huge splash in the in
• 3:10
  Speaker 1: the physics community. It made enormous waves jokes aside, when
• 3:14
  Speaker 1: it was discovered a few years ago. I mean, it's
• 3:16
  Speaker 1: the kind of thing where they discovered it and almost
• 3:18
  Speaker 1: immediately won the Nobel Prize for it. That's a big deal. Yeah,
• 3:22
  Speaker 1: But I guess that the truth is that I had
• 3:25
  Speaker 1: never heard about it until the big discovery was announced,
• 3:27
  Speaker 1: you know, and I'm pretty sort of plugged into research
• 3:30
  Speaker 1: and physicists, Um, but no, I hadn't. I had no
• 3:33
  Speaker 1: idea what these things were until I started hearing from
• 3:36
  Speaker 1: physicists like, hey, we think there's a big discovery about
• 3:40
  Speaker 1: to be announced. That's right. There were rumors bubbling around
• 3:42
  Speaker 1: for a while. But I don't think you're unusual. I
• 3:44
  Speaker 1: think before the discovery, nobody outside of physics had really
• 3:48
  Speaker 1: heard of gravitation of waves, and even most people inside
• 3:51
  Speaker 1: physics thought it was kind of a crazy backwater sub
• 3:53
  Speaker 1: field that might not ever amount to anything. But once
• 3:57
  Speaker 1: it happened, it was this huge splash and publicity and everything.
• 4:00
  Speaker 1: You think it's spread around the world and everybody would remember,
• 4:02
  Speaker 1: But I guess it's faded. Maybe if we've done this
• 4:04
  Speaker 1: a couple of years ago, just after the announcement, people
• 4:07
  Speaker 1: might know more or remember more, or at least be
• 4:10
  Speaker 1: better at pretending they knew something about it, right right.
• 4:12
  Speaker 1: Or maybe it's just kind of a reflection of how
• 4:14
  Speaker 1: we're all trapped in our little bubbles these days, you know, Like,
• 4:17
  Speaker 1: what feels like a huge deal that it's all over
• 4:20
  Speaker 1: the media to us, maybe somebody who lives in another
• 4:23
  Speaker 1: media bubble has it doesn't make it to them, you know, yeah, yeah, maybe,
• 4:28
  Speaker 1: Well One of the fun things about these interviews is
• 4:30
  Speaker 1: hearing people trying to figure it out as they're talking
• 4:32
  Speaker 1: to me, you know, like maybe it's has something to
• 4:35
  Speaker 1: do with the sun, or like it has waves on
• 4:38
  Speaker 1: people or something. I think that's a pretty insightful for
• 4:41
  Speaker 1: some psychologists to dig into, right, And it's been a
• 4:44
  Speaker 1: big deal in the fixed community for a while. I mean,
• 4:46
  Speaker 1: this the project that discovered these gravitational ways a few
• 4:49
  Speaker 1: years ago, Lego, that's been going on for years and years.
• 4:52
  Speaker 1: It's what's like one of the most expensive physics experiments ever, Right,
• 4:56
  Speaker 1: it's been going on for a long time. It's not
• 4:58
  Speaker 1: one of the most expensive. It's only six hundred something
• 5:02
  Speaker 1: million dollars. Oh my god, I can't even say that
• 5:05
  Speaker 1: for a I mean from the point of view like
• 5:09
  Speaker 1: the LHC, which is ten billion. Yeah, this is a
• 5:12
  Speaker 1: pretty cheap experiment. But the amazing thing is that it's
• 5:15
  Speaker 1: been going on for decades before it got results. I mean,
• 5:17
  Speaker 1: they've been working on this since the seventies and eighties
• 5:20
  Speaker 1: and they've been getting funding with no discovery for decades.
• 5:24
  Speaker 1: That's the kind of crazy blue sky research that I
• 5:27
  Speaker 1: think is wonderful. But it is happening less and less
• 5:29
  Speaker 1: these days. Well, let's break it down. What is a
• 5:34
  Speaker 1: gravitational wave? Right, So a gravitational wave, simply put, a
• 5:37
  Speaker 1: gravitational wave is a ripple in space. Right. Space itself
• 5:42
  Speaker 1: is not emptiness, it's not the backdrop of the Universe's
• 5:45
  Speaker 1: not nothing. It's a physical dynamical thing. It's like we're
• 5:48
  Speaker 1: fish swimming through water, right, and space is our is
• 5:51
  Speaker 1: our water. And so it turns out because space can
• 5:55
  Speaker 1: do things like bend and expand, it can also ripple,
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  Speaker 1: and so gravitational wave is a ripple in space itself.
• 6:02
  Speaker 1: So like if you were a fish your whole life
• 6:04
  Speaker 1: and you were just moving through water, you wouldn't think
• 6:06
  Speaker 1: of the water as a thing. It would just be
• 6:08
  Speaker 1: the thing you're moving around and right, that's right. You
• 6:10
  Speaker 1: might not even notice that it's there unless it did
• 6:13
  Speaker 1: something or had some effect on you. Right. And so
• 6:15
  Speaker 1: if you're a fish, you notice, oh, look there are currents,
• 6:18
  Speaker 1: I can serve those or whatever. And so we're starting
• 6:20
  Speaker 1: to notice the space is doing some stuff and that's
• 6:23
  Speaker 1: what makes us pay attention to it. Okay, So gravitational
• 6:25
  Speaker 1: wave is a ripple of the space itself, like the
• 6:28
  Speaker 1: space itself. We're in actually kind of ripples. Yeah, And
• 6:32
  Speaker 1: I think people might have an easier time understanding ripples
• 6:34
  Speaker 1: if they start first by thinking about other things that
• 6:36
  Speaker 1: basically do which are similar, like space bending. So space
• 6:40
  Speaker 1: is three dimensions, yeah, that we know of, right, that
• 6:43
  Speaker 1: we know of, yeah, down, forward, backward, left, right, But
• 6:46
  Speaker 1: it's hard to imagine space bending in three D, so
• 6:48
  Speaker 1: it's easier to think of it in two dimensions. So
• 6:50
  Speaker 1: typical examples think of like a big rubber sheet, that's space. Well,
• 6:54
  Speaker 1: space can be bent when you have big heavy objects
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  Speaker 1: sitting on it, like a like if you put a
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  Speaker 1: big bowl ball onto a rubber sheet, it's going to
• 7:02
  Speaker 1: distort it. And then if you, for example, if you
• 7:04
  Speaker 1: roll a marble across that sheet, it's not gonna anymore
• 7:07
  Speaker 1: move in a straight line. It's going to move like
• 7:09
  Speaker 1: in an orbit. Or if you've ever you know, spun
• 7:11
  Speaker 1: a coin down one of those crazy parabolic things in
• 7:15
  Speaker 1: a museum and send it seeing it to do crazy orbits.
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  Speaker 1: Space gets bent by mass, and that's what makes things
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  Speaker 1: go around the Sun, for example. So space is not
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  Speaker 1: like a flat, stiff sheet. It's like this kind of
• 7:27
  Speaker 1: wobbly kind of thing. That we're rolling along in. That's right,
• 7:30
  Speaker 1: we're rolling along it. We're moving in what seems like
• 7:33
  Speaker 1: the most natural path, the straightest line for us, unless
• 7:35
  Speaker 1: you get pushed in some direction. But if there's a
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  Speaker 1: big heavy thing near us, like the Earth or the Sun,
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  Speaker 1: pretty big massive stuff in the universe, then it bends
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  Speaker 1: that space and affects sort of the natural straight line
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  Speaker 1: we would travel in. And so people can practice thinking
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  Speaker 1: about space bending by understanding how big heavy masses can
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  Speaker 1: distort space, affecting the way that we move through it.
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  Speaker 1: And the subtle bit there is in the rubber sheet analogy,
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  Speaker 1: the two dimensional rubber sheet is bending into the third dimension, right,
• 8:05
  Speaker 1: which doesn't exist in the two D rubber sheet universe, um,
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  Speaker 1: But in the full three D example in the real
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  Speaker 1: universe that we're in, our space is not bending in
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  Speaker 1: some hidden, higher fourth dimensional universe. The bending is intrinsic.
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  Speaker 1: It's the relationship of objects in that space. So if
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  Speaker 1: you want to ask, like, what's the shortest distance through
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  Speaker 1: space for these two points that's affected by this bending
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  Speaker 1: of the space between them. Oh, so it's kind of
• 8:31
  Speaker 1: like the like, the relationship between things in space is
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  Speaker 1: what's changing, what's getting distorted exactly the relationship between things
• 8:39
  Speaker 1: in space. And when I first started thinking about this,
• 8:41
  Speaker 1: like space as a thing, even as a physicist, it's
• 8:44
  Speaker 1: pretty hard to think about because you imagine space as
• 8:47
  Speaker 1: being defined by distances or as you say, like the
• 8:49
  Speaker 1: relationship between things. And so I always wondered, like, how
• 8:53
  Speaker 1: could you even tell if space is bending? Because wouldn't
• 8:56
  Speaker 1: your rulers bend? Also, like don't you need some like
• 8:58
  Speaker 1: absolute external yard stick to notice if space is bending?
• 9:02
  Speaker 1: But you you would notice it, wouldn't you. Like if
• 9:05
  Speaker 1: I'm near a distorted space and I take my rule
• 9:07
  Speaker 1: ruler and I pointed one way, I would measure something
• 9:10
  Speaker 1: differently than if I pointed in another way. Yeah, exactly right.
• 9:13
  Speaker 1: And that depends a little bit on how your ruler
• 9:15
  Speaker 1: is built, Right, If your ruler is built out of
• 9:18
  Speaker 1: molecules like most rulers, and those molecules have a distance
• 9:21
  Speaker 1: between them that's fixed by like they're you know, the
• 9:25
  Speaker 1: forces between them, like you know, a standard wooden rulers
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  Speaker 1: held together by chemical bonds. Then those bonds are gonna
• 9:30
  Speaker 1: be stronger than like any space stretching, And so a
• 9:34
  Speaker 1: ruler like that is not going to be affected by
• 9:36
  Speaker 1: space getting stretched, and so it would certainly notice. But say,
• 9:39
  Speaker 1: for example, your ruler was like a bunch of equidistant
• 9:43
  Speaker 1: pebbles floating in space, right, then if space stretched, you
• 9:47
  Speaker 1: wouldn't even notice because the distances between those the pebbles
• 9:50
  Speaker 1: would grow and shrink as well, and you would have
• 9:52
  Speaker 1: no comparison. So you mean, like if you if you
• 9:54
  Speaker 1: measure distances kind of like they do in my home
• 9:56
  Speaker 1: country of Panama, It's not like you look at up
• 9:59
  Speaker 1: in a GPS map. It's more like, Okay, you go
• 10:01
  Speaker 1: down this street and then you make a ride at
• 10:02
  Speaker 1: the McDonald's, and you make a left at the gas station,
• 10:05
  Speaker 1: and that's how you get to my house. Then if
• 10:08
  Speaker 1: if like the terrain change, I wouldn't notice the difference
• 10:10
  Speaker 1: because I would still use these landmarks, still get to
• 10:13
  Speaker 1: McDonald's exactly, You still take a ride. Yeah. Yeah, So
• 10:17
  Speaker 1: if it's like an earthquake and suddenly McDonald's much further way,
• 10:19
  Speaker 1: it's still like, you know, it's one McDonald's away, still right, Well,
• 10:23
  Speaker 1: this is a perfect spot to take a break. We'll
• 10:25
  Speaker 1: be right back. So space is the squishy thing that
• 10:40
  Speaker 1: we're living in. It's not like a big vacuum or
• 10:44
  Speaker 1: an empty warehouse. It's like this squishy thing and it's
• 10:46
  Speaker 1: gonna squished by things that are heavy, and that can
• 10:50
  Speaker 1: affect how far things are apart from each other. So,
• 10:53
  Speaker 1: now a ripple is like what is that? Then? Like
• 10:56
  Speaker 1: a ripple in water? Is it similar to like a
• 10:58
  Speaker 1: ripple like her fish? It's a a poole gravitation wave,
• 11:01
  Speaker 1: like a ripple in the water. You know, like there's
• 11:03
  Speaker 1: an explosion underwater, we would feel that sort of shock wave.
• 11:06
  Speaker 1: That's exactly what it is. Yeah, And so if you
• 11:08
  Speaker 1: have two really heavy objects, for example, spinning around each other,
• 11:13
  Speaker 1: or one really massive object that's accelerated, the gravitational field
• 11:17
  Speaker 1: from that object is going to change really quickly. Right,
• 11:20
  Speaker 1: So imagine a static object is a gravitational field around it.
• 11:23
  Speaker 1: If that object accelerates or moves really its velocity has
• 11:27
  Speaker 1: changed really quickly, then the gravitational field itself is going
• 11:30
  Speaker 1: to change. And the wiggle in the field caused by
• 11:33
  Speaker 1: the acceleration of that object is a ripple. Right, It's
• 11:35
  Speaker 1: going to travel through space outward from that object. So
• 11:39
  Speaker 1: imagine you take like a rock, it has a gravitational field.
• 11:42
  Speaker 1: A rock is going to be bending space around it.
• 11:44
  Speaker 1: And then if you move that rock, something far away
• 11:47
  Speaker 1: is not going to notice instantaneously that you move the rock.
• 11:49
  Speaker 1: It can't tell that the gravity has changed yet because
• 11:52
  Speaker 1: the information about the rock moving travels at the speed
• 11:56
  Speaker 1: of light. How so, even gravity can only move at
• 11:59
  Speaker 1: the speed of light. That's right. Everything in the universe
• 12:01
  Speaker 1: that carries information can only move at the speed of
• 12:04
  Speaker 1: light or slower. And so, for example, say the Sun
• 12:08
  Speaker 1: disappeared magically, the Earth wouldn't notice for eight minutes. What
• 12:13
  Speaker 1: because that's how long it takes for light from the
• 12:15
  Speaker 1: Sun and for the gravity from the Sun to reach us.
• 12:18
  Speaker 1: So the path of the Earth wouldn't be affected for
• 12:20
  Speaker 1: eight minutes. So there'll be eight minutes where there was
• 12:22
  Speaker 1: no Sun, but the Earth would just keep going like hey,
• 12:25
  Speaker 1: we wouldn't see it gone either, right, because the light
• 12:27
  Speaker 1: would also take eight minutes to get here. That's right.
• 12:30
  Speaker 1: The Sun could have disappeared five minutes ago and we
• 12:32
  Speaker 1: would have no idea. Don't rush outside and look at
• 12:35
  Speaker 1: the sun. Everybody, Please don't know. I'm scared, Daniel. Anyway,
• 12:39
  Speaker 1: that scenario, there's nothing you can do in that scenario,
• 12:41
  Speaker 1: So there's no point in preparing for it. But the
• 12:43
  Speaker 1: point is that the gravitational information moves through space the
• 12:47
  Speaker 1: same speed everything else does, and so if something is
• 12:49
  Speaker 1: changing really quickly, then that like increasing gravity decreasing gravity,
• 12:54
  Speaker 1: would sort of travel would take a while to get
• 12:56
  Speaker 1: to me, and I would see that as kind of
• 12:58
  Speaker 1: a wave, like a ripple. Yeah, exactly. Imagine somebody's turning
• 13:02
  Speaker 1: the Sun on and off. It exists, it disappears, it exists,
• 13:05
  Speaker 1: it disappears. Then the gravitational field of the sun, this
• 13:08
  Speaker 1: bending of space is going to disappear and then snap
• 13:11
  Speaker 1: back and disappear and snap back. And what we would
• 13:13
  Speaker 1: see it on Earth is gravity turning on and off
• 13:16
  Speaker 1: and on and off, and those would be enormous ripples
• 13:19
  Speaker 1: in a gravitational field. Yeah. Wow, Well, I think what's
• 13:22
  Speaker 1: cool is that, you know, we won talks about it
• 13:24
  Speaker 1: like it's um it has to be like two black
• 13:27
  Speaker 1: holes or something huge and massive, But it's really like
• 13:30
  Speaker 1: everything generates gravitational waves, right like you and I. If
• 13:34
  Speaker 1: I move my arms back and forth, it's I'm generating
• 13:37
  Speaker 1: gravitational waves, that's right. And you happen to be a
• 13:40
  Speaker 1: very magnetic person or gravitational person, so I sense those
• 13:43
  Speaker 1: waves from your head, and I'm glad you didn't say heavy,
• 13:46
  Speaker 1: thank you. I know I was about to say that.
• 13:49
  Speaker 1: I was trying to steal clear of it. Um. Yeah,
• 13:51
  Speaker 1: you're right. Everything that has mass bend space, and anything
• 13:54
  Speaker 1: that has mass and is accelerated will be generating gravitational waves.
• 13:59
  Speaker 1: But the thing for people to member is that gravity
• 14:01
  Speaker 1: is super duper crazy, ridiculously weak, which is why, for example,
• 14:06
  Speaker 1: if you're sitting next to somebody in a train, you
• 14:08
  Speaker 1: don't feel a literal gravitational force between you. There is
• 14:11
  Speaker 1: one there, but you can't even sense it because it's
• 14:14
  Speaker 1: so tiny compared to the gravitational force of you in
• 14:16
  Speaker 1: the Earth, no matter how attractive that person is. That's right,
• 14:19
  Speaker 1: you might be feeling other forces, and you know, feel
• 14:21
  Speaker 1: free to act on that or not not to you,
• 14:24
  Speaker 1: there's no physics advice about whether or not to approach
• 14:26
  Speaker 1: people on a train. But your point is correct. Everything
• 14:29
  Speaker 1: is generating gravitational waves that has mass and is accelerating, right,
• 14:32
  Speaker 1: But they're so weak. Yeah, you need something really really
• 14:35
  Speaker 1: huge in order to be able to detect them. Okay, well,
• 14:38
  Speaker 1: let's talk about how we even came up with this
• 14:42
  Speaker 1: idea of a gravitation wave. Right, who sits around thinking, hey,
• 14:45
  Speaker 1: I wonder if ripple, if gravity and spacetime itself can
• 14:48
  Speaker 1: generate waves, Well, your first guests would probably be right
• 14:52
  Speaker 1: in that case, because the first person to think about
• 14:54
  Speaker 1: that was Albert Einstein. Right, everybody's going to scientists in
• 14:57
  Speaker 1: this case. It is exactly right. He came up with
• 15:00
  Speaker 1: this theory of general relativity, and the core idea in
• 15:04
  Speaker 1: that theory is that gravity is not a force but
• 15:06
  Speaker 1: a bending of space. And so a very natural consequence
• 15:10
  Speaker 1: of his theory was that if things accelerate, then it
• 15:13
  Speaker 1: would make these ripples in the bending of space, and
• 15:16
  Speaker 1: those ripples he called gravitational waves. Oh, I see. It's like,
• 15:20
  Speaker 1: once you come up with the idea that space can
• 15:22
  Speaker 1: bend and that and that also this information about space
• 15:26
  Speaker 1: bending can't travel faster than light, than you're naturally or
• 15:29
  Speaker 1: left with the idea that, um, you can have these
• 15:32
  Speaker 1: waves traveling through space for gravity. Yeah, exactly. But a
• 15:37
  Speaker 1: funny wrinkle in the story, or ripple in the story,
• 15:39
  Speaker 1: if you like, is that Einstein he thought about these
• 15:42
  Speaker 1: things as sort of a theoretical possibility or an abstract idea.
• 15:46
  Speaker 1: But he I think he wrote in his paper. He's like,
• 15:48
  Speaker 1: he said, but we could never discover these because they're
• 15:51
  Speaker 1: too small. Even Einstein, who predicted these things, thought it
• 15:55
  Speaker 1: would be impossible for us to ever detect them, which
• 15:58
  Speaker 1: is like even more kudo to the experiment mentalists for
• 16:01
  Speaker 1: proving Einstein wrong by proving him right. Wow. So even
• 16:05
  Speaker 1: Einstein didn't think that it would be possible to measure
• 16:07
  Speaker 1: these But they've done it. They did it a couple
• 16:09
  Speaker 1: of years ago. Yeah. And you know, there's one way
• 16:11
  Speaker 1: in which I personally agreed with Einstein, because I remember
• 16:14
  Speaker 1: when I was choosing where to go for graduate school,
• 16:17
  Speaker 1: I was visiting various institutions and thinking about what physics
• 16:20
  Speaker 1: they were doing, and I went to cal Tech and
• 16:22
  Speaker 1: cal Tech is one of the leading institutions on LAGO,
• 16:25
  Speaker 1: and I was actually got to talk to one of
• 16:26
  Speaker 1: the leading scientists on it at the time. He was
• 16:28
  Speaker 1: telling me about about this project, and I thought, Wow,
• 16:31
  Speaker 1: this sounds cool but really hard and basically impossible, and
• 16:34
  Speaker 1: I would be crazy to sign up to do a
• 16:37
  Speaker 1: pH d in this. I thought, they're never going to
• 16:39
  Speaker 1: see these things. It's impossible and ridiculous. More power to you,
• 16:43
  Speaker 1: but I'm going to go do particle physics. On that note,
• 16:46
  Speaker 1: let's take a quick break. The skills are problem is insane, right, Like,
• 17:01
  Speaker 1: it's first of all, you need uh, something momentous happening,
• 17:05
  Speaker 1: like two black holes spinning around each other so fast
• 17:10
  Speaker 1: and I'm just about to like crash together, right yeah,
• 17:13
  Speaker 1: really really massive objects, and you need a lot of acceleration. Also,
• 17:17
  Speaker 1: as you say, for example, black holes smashing into each
• 17:20
  Speaker 1: other does that. And the reason is that the very
• 17:22
  Speaker 1: last moment before the black holes collide into each other,
• 17:25
  Speaker 1: they're moving super fast. It's a huge acceleration there, because
• 17:29
  Speaker 1: you know, we think of black holes crashing like they
• 17:32
  Speaker 1: travel the straight line and they crash into each other,
• 17:34
  Speaker 1: but they don't write They actually kind of get close
• 17:36
  Speaker 1: to each other, and then they start circling each other,
• 17:39
  Speaker 1: and then that circling gets smaller and smaller and smaller
• 17:41
  Speaker 1: and smaller. Yeah, exactly, they spin around each other a
• 17:43
  Speaker 1: little bit um unless you build like a black hole
• 17:46
  Speaker 1: collider to shoot them exactly at each other. And you know,
• 17:49
  Speaker 1: anybody out there who knows how to do that, give
• 17:51
  Speaker 1: me a call. But if two natural black holes that
• 17:54
  Speaker 1: approach each other are going to already have some relative
• 17:56
  Speaker 1: angler momentum. So they're going to keep that relative spin
• 17:59
  Speaker 1: from each other there, So they're going to keep that
• 18:01
  Speaker 1: and then they're just going to spin around each other.
• 18:02
  Speaker 1: As you get closer and closer to have the same
• 18:05
  Speaker 1: anglar momentum, they're gonna have to go faster and faster.
• 18:07
  Speaker 1: Kind of like when you flush the toilet. You know,
• 18:09
  Speaker 1: two things floating there, spinning around each other, and then
• 18:11
  Speaker 1: as they get closer and closer, they starts being really
• 18:13
  Speaker 1: really fast. Yes, exactly, the dark matter in your toilet,
• 18:17
  Speaker 1: the other from the black hole. Yeah, exactly, it spins
• 18:22
  Speaker 1: around each other. I was going to say, more like
• 18:23
  Speaker 1: an ice skater spins around faster and faster as she
• 18:26
  Speaker 1: pulls her arms in. But yes, also dark matter on
• 18:29
  Speaker 1: your toilet does the same. Yeah. And then right right
• 18:32
  Speaker 1: before it flushes down, it's been so fast, that's when
• 18:35
  Speaker 1: these generates massive gravitational waves. Right, that's the idea, that's right.
• 18:39
  Speaker 1: So Jorges take away from this topic is every time
• 18:41
  Speaker 1: you flush the toilet, you're generating gravitational which is true,
• 18:45
  Speaker 1: which is taking which is technically accurately true. Yes, yes, yes,
• 18:49
  Speaker 1: And you have a physicist now on record saying that, um.
• 18:52
  Speaker 1: But in the case of the cosmic toilet, you know,
• 18:55
  Speaker 1: black holes actually swish around each other and flush themselves away. Um,
• 18:59
  Speaker 1: what happens is get these ripples, and when the ripple
• 19:01
  Speaker 1: passes through Earth, it squeezes the space in one direction
• 19:05
  Speaker 1: and stretches it in the other. That's the effect of
• 19:08
  Speaker 1: the ripple on Earth. So if we want to see it,
• 19:10
  Speaker 1: we have to have a very accurate ruler pointing in
• 19:13
  Speaker 1: two directions, one ninety degrees from the other, so we
• 19:16
  Speaker 1: can see a squeeze in one way and a stretch
• 19:19
  Speaker 1: in the other direction at the same time. So the
• 19:21
  Speaker 1: direction of the wave um tells you where it was
• 19:24
  Speaker 1: coming from. Also, and you want to calibrate yourself by
• 19:27
  Speaker 1: having measurements in the direction of the wave and ninety degrees. Also,
• 19:31
  Speaker 1: because you don't know which direction the wave is going
• 19:34
  Speaker 1: to come from, you want to make sure to be
• 19:35
  Speaker 1: sensitive to it no matter where it comes. So you
• 19:38
  Speaker 1: have to basically really careful rulers that are ninety degrees
• 19:42
  Speaker 1: or arrange from each other so you can be sensitive
• 19:44
  Speaker 1: to any direction. But it's crazy because even though these
• 19:46
  Speaker 1: are generated by two colliding black holes, by the time
• 19:50
  Speaker 1: they get to is these waves are like really faint, right, Yeah,
• 19:53
  Speaker 1: there really are, tim I mean Einstein had a good point.
• 19:56
  Speaker 1: In order to see these things, you have to see
• 19:58
  Speaker 1: space shrink by one fact to intend to the twenty right,
• 20:02
  Speaker 1: that's ten with twenty zeros after it. It's like if
• 20:05
  Speaker 1: you had a meter stick that was ten to the
• 20:09
  Speaker 1: twenty meters long, you would have to see it shrink
• 20:12
  Speaker 1: by one meter, yeah, exactly. Yeah, Or if you wanted
• 20:15
  Speaker 1: to see something shrink by like a millimeter, you'd have
• 20:18
  Speaker 1: to have a yard stick that's like, you know, ten
• 20:21
  Speaker 1: six tillion long or something crazy. It's really ridiculous. It's
• 20:25
  Speaker 1: like the size of our solar system, right, yeah, I
• 20:27
  Speaker 1: think so. And so you can imagine not only is
• 20:30
  Speaker 1: it really hard to see things that are small, but
• 20:33
  Speaker 1: other things are affecting you, right, not not that anything
• 20:36
  Speaker 1: else is shaping space that same way. But if you
• 20:39
  Speaker 1: have a ruler, how do you even know how long
• 20:41
  Speaker 1: it is to tend to the twenty right to one
• 20:43
  Speaker 1: part in tend of the twenty And you detect um
• 20:46
  Speaker 1: when it's wiggling, Like if you just heat up your ruler,
• 20:49
  Speaker 1: it's going to get a little longer. If you if
• 20:51
  Speaker 1: you cool down your ruler, it's going to get a
• 20:53
  Speaker 1: little shorter. So the experimental trouble of seeing something so
• 20:57
  Speaker 1: tiny is really really it's it's really difficult, and it's
• 21:00
  Speaker 1: really an amazing Coudi graw that they pulled it off.
• 21:04
  Speaker 1: So it's like if I was standing on one end
• 21:06
  Speaker 1: of the solar system and you were standing on the
• 21:08
  Speaker 1: other side of the solar system, it would be like asking, like, hey, Daniel,
• 21:11
  Speaker 1: did you feel the space between us shrink by one
• 21:14
  Speaker 1: millimeter exactly? That's that's crazy. It's pretty crazy, and so
• 21:19
  Speaker 1: in order to do it, they had to come up
• 21:20
  Speaker 1: with some pretty crazy technology. The way they do it
• 21:23
  Speaker 1: is really awesome and beautiful. I mean, there's fascinating theoretical stuff,
• 21:26
  Speaker 1: but the experimental side of it I love also because
• 21:28
  Speaker 1: they had to come up with new techniques that nobody
• 21:30
  Speaker 1: had ever used before. So this is the LIGO project,
• 21:36
  Speaker 1: right l I GEO, Yeah, that's right. LIGO stands for
• 21:41
  Speaker 1: laser interferometric I think gravitational observatory LIGO. Not to be
• 21:46
  Speaker 1: confused with LEGO. That's right. Legos almost as expensive as LEGO.
• 21:51
  Speaker 1: But the way they do it is they have these
• 21:53
  Speaker 1: two rulers that are you know, four kilometers long each
• 21:57
  Speaker 1: and they shoot a beam of laser light all the
• 22:00
  Speaker 1: way down this tunnel and then it bounces off a
• 22:02
  Speaker 1: mirror and comes back, and they do that simultaneously along
• 22:06
  Speaker 1: both legs. And then when the lasers come back, they
• 22:09
  Speaker 1: can tell how far the light went by comparing how
• 22:14
  Speaker 1: many wiggles it's made. So it's kind of like um,
• 22:17
  Speaker 1: like a really race, right, Like you send a laser
• 22:19
  Speaker 1: beam out and then you measure how long it tastes
• 22:21
  Speaker 1: for it to come back, and that's how you know
• 22:23
  Speaker 1: how far it went. Yeah, but you don't need to
• 22:26
  Speaker 1: measure the time because lasers are light and light has
• 22:29
  Speaker 1: wave like properties and so it wiggles. So if you
• 22:32
  Speaker 1: send out two beams of lasers um and then at
• 22:35
  Speaker 1: the same direction and they bounce off mirrors and come back,
• 22:38
  Speaker 1: they're gonna be wiggling all the way there and wiggling
• 22:41
  Speaker 1: all the way back. And when they come back, they
• 22:42
  Speaker 1: should be the same place in their wiggle, right either
• 22:45
  Speaker 1: up or down. And if they're in the same place
• 22:47
  Speaker 1: in their wiggle, they'll add up together. If they're opposite
• 22:50
  Speaker 1: places in their wiggle, like one of them went a
• 22:52
  Speaker 1: little bit further and now instead of being in the
• 22:54
  Speaker 1: up wiggle it's at the down wiggle. Then those two
• 22:57
  Speaker 1: will add up to be zero destructive interference. And so
• 23:00
  Speaker 1: that's the interferometer. Part of the of the of the
• 23:03
  Speaker 1: experiment is that they send out these two pulses of
• 23:05
  Speaker 1: lasers and when they come back, they see are they
• 23:08
  Speaker 1: interfering positively by adding up on top of each other
• 23:11
  Speaker 1: or interfering negatively by canceling each other out. They're interfering negatively.
• 23:15
  Speaker 1: It means one of them wiggles a little bit longer
• 23:18
  Speaker 1: than the other one were a little bit shorter, and
• 23:20
  Speaker 1: now they're out of sync. I see. So it's not
• 23:21
  Speaker 1: like you're measuring whether the distance in one direction change.
• 23:25
  Speaker 1: You're measuring whether it change relative to the other direction exactly.
• 23:29
  Speaker 1: And that's what these ways do. They shrink space in
• 23:32
  Speaker 1: one direction and stretch it in the other direction exactly,
• 23:35
  Speaker 1: And so that's what you're looking for. And they actually
• 23:37
  Speaker 1: have multiple observatories. They have one in Louisiana and one
• 23:40
  Speaker 1: in Washington State, and they're finishing one or just finished
• 23:43
  Speaker 1: one in Italy, and they're building other ones around the
• 23:46
  Speaker 1: world and the idea and they're all pointed in different directions,
• 23:49
  Speaker 1: and there are different locations so you can use those
• 23:51
  Speaker 1: multiple telescopes to tell you like is it real you know,
• 23:54
  Speaker 1: or is it just like a semi truck driving over
• 23:56
  Speaker 1: it which is shaking all of my mirrors, or and
• 23:58
  Speaker 1: you can also do it to tell where did it
• 24:00
  Speaker 1: come from, because if it landed in Washington before it
• 24:03
  Speaker 1: landed in Louisiana, then you can tell which direction it
• 24:06
  Speaker 1: came from. You can use it to sort of triangulate.
• 24:08
  Speaker 1: It's interesting how the word telescope changes right because of physicists. Right,
• 24:12
  Speaker 1: like people think of the telescope. Is this tube that
• 24:16
  Speaker 1: you look through to tell how far ships are away
• 24:19
  Speaker 1: from me or something, or how far land is, that's
• 24:21
  Speaker 1: a telescope. But nowadays telescope and science way means you know,
• 24:25
  Speaker 1: it could mean a giant antenna, or it could mean
• 24:27
  Speaker 1: like an array of antennas, or it could be like
• 24:29
  Speaker 1: these crazy long laser tunnels spread all over the world.
• 24:33
  Speaker 1: Like you call that a telescope. Yeah, well I think telescope.
• 24:36
  Speaker 1: I'm not a linguist, but I think telescope essentially means
• 24:39
  Speaker 1: seeing far away, and so you can just generalize it
• 24:42
  Speaker 1: to mean we don't have to see only with light, right,
• 24:45
  Speaker 1: we can see with other things, And so you're right.
• 24:48
  Speaker 1: I think that's an awesome use of the word telescope,
• 24:49
  Speaker 1: because as we invent new kinds of technologies and new
• 24:52
  Speaker 1: kinds of telescopes, it gives us other ways to look
• 24:55
  Speaker 1: out into the universe. Right, and you know, we're in
• 24:57
  Speaker 1: this tiny little dot in a corner of the universe,
• 25:00
  Speaker 1: desperately drinking in the information that the universe is sending
• 25:03
  Speaker 1: to us. It's wonderful to imagine. Can we have another
• 25:06
  Speaker 1: way to listen to the universe? Can we have another
• 25:09
  Speaker 1: way to get information about where we are and what's
• 25:11
  Speaker 1: going on around us? Well, that's what people say. It's
• 25:13
  Speaker 1: so significant about the discovery of gravitation waves is that
• 25:16
  Speaker 1: it gives us another way to listen to the universe.
• 25:20
  Speaker 1: Right as people say that it's like a new way
• 25:22
  Speaker 1: of listening to the universe. Yeah, that's right, and it
• 25:25
  Speaker 1: is amazing and dramatic. Um a couple of quibbles though.
• 25:28
  Speaker 1: Sometimes people say it's the first time we have another
• 25:31
  Speaker 1: way to listen to the universe. Right, they say, forever
• 25:34
  Speaker 1: we've been doing astronomy using only light, and now we
• 25:37
  Speaker 1: have a second method. It's not exactly true, because we
• 25:40
  Speaker 1: have also have particles. For example, we've been using new
• 25:42
  Speaker 1: trinos to look at the universe, and we've been detecting
• 25:45
  Speaker 1: neutrinos for a while now. So it is true that
• 25:48
  Speaker 1: we're adding to our our tool belt by adding gravitational waves,
• 25:52
  Speaker 1: and it's hugely important and fascinating, but it's not the
• 25:55
  Speaker 1: first time we have a new tool in our So
• 25:57
  Speaker 1: primarily before the only way we've even know about the
• 26:00
  Speaker 1: rest of the universe or what's going on is by
• 26:03
  Speaker 1: the light or the particles that come to us. Yeah,
• 26:06
  Speaker 1: the photons from stars and from other galaxies. Yeah, it's
• 26:09
  Speaker 1: all been photons, Like the radio waves, those are all
• 26:11
  Speaker 1: photons and in light, different kinds of light. But now
• 26:15
  Speaker 1: in addition to particles and light, we have this other
• 26:18
  Speaker 1: way of like knowing what's going on elsewhere in the universe,
• 26:21
  Speaker 1: which is these gravitational waves. And it's really important, not
• 26:24
  Speaker 1: just because it's cool, new shiny tool, which is fun,
• 26:27
  Speaker 1: but because gravitational waves can do things that particles can't. Right,
• 26:30
  Speaker 1: gravitational waves are not moving through space, so they're not
• 26:33
  Speaker 1: like blocked the way things move through space are, right,
• 26:37
  Speaker 1: there's no dust cloud that can block a gravitational wave.
• 26:40
  Speaker 1: They don't get like attenuated. If they hit a big
• 26:42
  Speaker 1: black hole or something, well, they can be they attenuated
• 26:45
  Speaker 1: the further way you are, right, like everything else, they
• 26:47
  Speaker 1: spread out through space and they get weaker and weaker,
• 26:49
  Speaker 1: but they can't be blocked by matter. I mean they
• 26:52
  Speaker 1: can get they can if you have another gravitational wave,
• 26:54
  Speaker 1: you can they can get reflected or distorted or something.
• 26:56
  Speaker 1: But it's a it's penetrates through things which are otherwise
• 26:59
  Speaker 1: invisible to us and can send us messages from inside
• 27:03
  Speaker 1: things that otherwise would be opaque to us. And so
• 27:06
  Speaker 1: it's a really powerful, fascinating new tool. It really is
• 27:09
  Speaker 1: like we're opening up a new kind of eye to
• 27:11
  Speaker 1: the universe for the first time. One of the other
• 27:14
  Speaker 1: crazy things about gravitational waves is that we had no
• 27:17
  Speaker 1: idea how often they came, right. One tricky thing is
• 27:20
  Speaker 1: can you see them at all? Right? The second tricky
• 27:23
  Speaker 1: thing was are there any anyway? Right? It could have
• 27:25
  Speaker 1: been that we're really good at seeing them. We developed
• 27:28
  Speaker 1: this amazing technology, were super sensitive to these tiny little effects.
• 27:31
  Speaker 1: But they only come once every hundred years. You mean,
• 27:33
  Speaker 1: like the kinds of events that would generate them in
• 27:36
  Speaker 1: a large enough way for us to detect may not
• 27:39
  Speaker 1: be happening as as often as we think, like these
• 27:41
  Speaker 1: black holes crashing into each other, or these neutron stars
• 27:45
  Speaker 1: flushing down the toilet. Maybe these things were rare, right, Yeah,
• 27:49
  Speaker 1: we didn't know, right, And but the first time that
• 27:51
  Speaker 1: they turned on the experiment with their new powerful capability.
• 27:55
  Speaker 1: They've been incrementally improving it for decades, but when they
• 27:58
  Speaker 1: first got to the place where they thought, okay, now
• 28:00
  Speaker 1: we really think we can see them, they saw one
• 28:02
  Speaker 1: within like a day of the first time they turned
• 28:04
  Speaker 1: it on. It was incredible. And now they've been seeing many, many, many.
• 28:08
  Speaker 1: They have like a huge pile of these things they've
• 28:10
  Speaker 1: been studying, and so that's really exciting because it could
• 28:13
  Speaker 1: have been that you turned on this new telescope and
• 28:15
  Speaker 1: the universe was just really quiet and there's nothing, didn't
• 28:17
  Speaker 1: really have anything to say, But it turns out it's
• 28:19
  Speaker 1: got a lot to say, and these things happen more
• 28:21
  Speaker 1: often than people hoped, and so now we can learn
• 28:24
  Speaker 1: more about like things like the black holes crushing, right,
• 28:26
  Speaker 1: and neutron stars crushing and what happens in those like
• 28:29
  Speaker 1: extreme moments of physics. Yeah, yeah, exactly. So I think
• 28:33
  Speaker 1: one of the really exciting things is that we have
• 28:36
  Speaker 1: this new eye on the universe, this knew way to
• 28:38
  Speaker 1: look at the universe. And in addition, there's cool stuff
• 28:42
  Speaker 1: to see. Right, So one of the cool things they
• 28:44
  Speaker 1: saw recently was not just two black holes colliding, but
• 28:47
  Speaker 1: two neutron stars colliding well. And the fascinating thing about
• 28:51
  Speaker 1: that is that they saw through the gravitational waves and
• 28:54
  Speaker 1: at the same time they saw through telescopes using normal light,
• 28:58
  Speaker 1: So they could see these two things happen end through
• 29:00
  Speaker 1: two kinds of vision overlaid on top of each other.
• 29:03
  Speaker 1: That was really pretty awesome. Yeah. I like the way
• 29:06
  Speaker 1: they always describe this project, which is which is very poetic.
• 29:10
  Speaker 1: I feel like it's like they always say, imagine if
• 29:12
  Speaker 1: you're deaf your whole life. I mean, you could look
• 29:15
  Speaker 1: look around you, but you can't hear anything, and then
• 29:18
  Speaker 1: all of a sudden, somebody gives you the ability to
• 29:20
  Speaker 1: hear stuff, and so now you not only can you
• 29:23
  Speaker 1: see stuff with light, but you can also kind of
• 29:26
  Speaker 1: hear them through this whole other channel. Yeah, there's some
• 29:29
  Speaker 1: poetry there. Sometimes I think they take it a a little
• 29:31
  Speaker 1: too far because in science communication articles about this, they
• 29:36
  Speaker 1: often describe this as listening to the universe, or and
• 29:39
  Speaker 1: you can hear the chirp, you know. I think that
• 29:41
  Speaker 1: gives people the impression that gravitational waves are sound, or
• 29:45
  Speaker 1: that colliding black holes make a sound. Remember that space
• 29:48
  Speaker 1: is quiet. Sound can't go through space because there's no air.
• 29:52
  Speaker 1: So these are gravitational waves, and you can take the
• 29:55
  Speaker 1: frequency of those waves and transform it into sound waves
• 29:58
  Speaker 1: and listen to it. Way you can take the frequency
• 30:01
  Speaker 1: of anything and transform it into sound waves, like people
• 30:04
  Speaker 1: took the Higgs Boson events and transform them into sound waves,
• 30:08
  Speaker 1: and you're like listening to the Higgs boson. I don't
• 30:10
  Speaker 1: really think you're listening to the Higgs boson, so you're
• 30:12
  Speaker 1: not really listening to the universe. But poetically, I agree,
• 30:15
  Speaker 1: it's another way to get information from the universe. Yeah,
• 30:19
  Speaker 1: it totally works as an analogy, but I think some
• 30:22
  Speaker 1: people think it's literal, and I just want to make
• 30:24
  Speaker 1: the point that it's not literally listening to the universe.
• 30:27
  Speaker 1: These are gravitational waves, not sound waves, although they kind
• 30:31
  Speaker 1: of propagate in a similar way right well, in the
• 30:33
  Speaker 1: same way that that waves do propagate. But you know,
• 30:36
  Speaker 1: water waves are compression waves through a medium and gravitational
• 30:39
  Speaker 1: waves are ripples in space, and so it's a little
• 30:43
  Speaker 1: bit different. But and the analogy is very very useful
• 30:46
  Speaker 1: as long as you remember it's an analogy. Don't stick
• 30:48
  Speaker 1: your ear into space and expect to hear gravitational waves.
• 30:51
  Speaker 1: Not a good idea. Yeah, I know, it's like it's
• 30:53
  Speaker 1: very poetic. It's like, all of a sudden you can
• 30:55
  Speaker 1: hear and suddenly you're hearing all these toilet flushings across
• 30:58
  Speaker 1: the costmos. It's very poetic. Exactly listen to the universe
• 31:03
  Speaker 1: flushing away its waste. Well, on that note, thank you
• 31:06
  Speaker 1: very much for listening. I hope you guys enjoyed that discussion.
• 31:09
  Speaker 1: It's a pretty heavy topic and I hope we handled
• 31:12
  Speaker 1: it with gravitas. Yeah, I hope you didn't get gravitation
• 31:15
  Speaker 1: at least. All right, Well, thank you very much. Have
• 31:18
  Speaker 1: a great day, guys. Do you have a question you
• 31:25
  Speaker 1: wish we would cover, Send it to us. We'd love
• 31:28
  Speaker 1: to hear from you. You can find us on Facebook, Twitter,
• 31:31
  Speaker 1: and Instagram at Daniel and Jorge One Word, or email
• 31:35
  Speaker 1: us to feedback at Daniel and Jorge dot com.