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What is a graviton? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, hey, it's that time again. What are we talking
0:11
Speaker 1: about today? It's time to talk about particle names, my
0:16
Speaker 1: favorite subject. Hey, don't blame me. There are a lot
0:18
Speaker 1: of particles out there. All right, let's do it, Daniel. Well,
0:21
Speaker 1: today's game is I'm gonna give you a word and
0:24
Speaker 1: you have to guess whether it's the name of a
0:27
Speaker 1: fundamental particle or the name of a character in the Transformers.
0:32
Speaker 1: All right, I'm ready to me alright, first one, Megatron,
0:35
Speaker 1: that one down to give me. That's definitely a Transformer.
0:38
Speaker 1: All right, that was the warm up. How about Galvatron.
0:42
Speaker 1: I'm gonna go with particle alright, Computron, I'm gonna go
0:46
Speaker 1: with the Transformer or eighties computer company? Alright. Last one
0:52
Speaker 1: is tripp to con That sounds more like a convention
0:55
Speaker 1: for pleasant nerds. Hey, I want to go to that.
0:59
Speaker 1: That sounds awesome. Yeah, alright, Which ones are particles and
1:04
Speaker 1: which ones are Transformers? All right? It was a bit
1:07
Speaker 1: of a trick question. They were all names of Transformers.
1:10
Speaker 1: What I had to do a bit of deep research.
1:14
Speaker 1: But those are actual Transformer character names. Oh man, you
1:18
Speaker 1: got me, all right, but you have to promise me
1:20
Speaker 1: if you ever discover a particle Daniel at the large
1:23
Speaker 1: Headron collider. You have to name it Mega Tromp done.
1:45
Speaker 1: Hi am Jorge. I'm a cartoonists and the creator of
1:47
Speaker 1: PhD comics. Hi I'm Daniel. I'm a particle physicist, a
1:51
Speaker 1: closet transformer geek, and definitely a nerd. And Welcome to
1:55
Speaker 1: our podcast. Daniel and Jorge explain eighties toy franchises. No,
1:59
Speaker 1: I mean Daniel and Orge explained the universe a production
2:03
Speaker 1: of My Heart Radio. I Heart Radio is going to
2:05
Speaker 1: get sued now by mattel or whoever puts out the transformers.
2:08
Speaker 1: This is the first domino, isn't it the beginning of
2:10
Speaker 1: the downfall of the podcast? Um? But welcome to our podcast,
2:13
Speaker 1: in which we take crazy, amazing things that blow your
2:17
Speaker 1: mind and try to relate them to silly, fun easily
2:20
Speaker 1: understandable things like robots that turn into cars or airplanes
2:24
Speaker 1: or you know, dinosaurs. Television transforms are very versatile. I
2:28
Speaker 1: never understood the dinosaur thing, Like, you're already a killer robot.
2:31
Speaker 1: What's the advantage of transforming into a dinosaur? Like? Seriously,
2:35
Speaker 1: I mean, think about this robot versus dinosaur. Who wins
2:38
Speaker 1: robot every time, right, I think they're just trying to
2:41
Speaker 1: blend in with the other dinosaurs. All these are prehistoric transformers,
2:45
Speaker 1: robots in disguise. So if transformers had come to Earth
2:48
Speaker 1: before the dinosaurs, wouldy have transformed into like insects and
2:52
Speaker 1: like trilobytes and stuff like that. They did, they there's
2:54
Speaker 1: this transformer for everything. But anyways, welcome to a podcast
2:59
Speaker 1: in which we talk about all the things in universe,
3:02
Speaker 1: the big ones, the small ones, the ones that maybe
3:05
Speaker 1: don't even exist. That's right, and we love delving into
3:07
Speaker 1: these theoretical hypothetical topics, and so today we're going to
3:10
Speaker 1: talk about a very interesting concept, right Daniel, which is
3:14
Speaker 1: something that maybe in your everyday life, affecting you on
3:17
Speaker 1: a daily, every second of your life basis um, but
3:21
Speaker 1: which physicists don't even know if it exists or not.
3:24
Speaker 1: That's right. This relates to something you experience every day,
3:27
Speaker 1: but physics still doesn't really understand that kind of thing,
3:31
Speaker 1: which in two hundred years people will look back and say, man,
3:34
Speaker 1: I wish I had had those ideas. I totally would
3:36
Speaker 1: have gotten the Nobel Prize. The puzzle was right there
3:38
Speaker 1: in front of them and it's something that I think
3:41
Speaker 1: you've told me this before that if it exists, it
3:44
Speaker 1: may totally upend all of our theories about physics, right,
3:47
Speaker 1: that's right. One of the challenges with this kind of
3:50
Speaker 1: idea is that we don't even really know how to
3:52
Speaker 1: form the idea, Like the idea itself has problems, not
3:55
Speaker 1: to mention whether or not it exists, but we can't
3:57
Speaker 1: even really seem to get it to behave its on
4:00
Speaker 1: the page, so to the On the podcast, we'll be
4:03
Speaker 1: talking about the graviton. What is the graviton? Is it
4:12
Speaker 1: a transformer for a transformer? Is it a particle? Is it?
4:18
Speaker 1: And how is it pronounced? Really? Is it graviton or
4:21
Speaker 1: is it gravyton? Or yeah? What kind of transformer would
4:24
Speaker 1: the gravyton be? Shoot streams of hot gravy at you
4:27
Speaker 1: or something transformed into a gravy bowl? Oh? Man, so
4:32
Speaker 1: terrifying grav versus turkey tron, based, the based or based
4:40
Speaker 1: or bot. No, but it's a funny name. And you know,
4:44
Speaker 1: you are often a critic of physics naming, and so
4:48
Speaker 1: you know, if the folks have done a good job
4:50
Speaker 1: in this case, then the name should be pretty clear, right,
4:52
Speaker 1: that's your mattress, name something in a clear way, so
4:56
Speaker 1: not knowing anything about it, just knowing the name. What
4:59
Speaker 1: do you imagine the A baton means the gravytan um
5:04
Speaker 1: you has something to do with graves or I imagine
5:06
Speaker 1: it has something to do with gravity, like a gravity thing.
5:09
Speaker 1: I like how you first went for gravy, second went
5:12
Speaker 1: for graves, and only third on the Physics podcast considered
5:16
Speaker 1: we might be talking about gravity. So yeah, it's a
5:19
Speaker 1: particle related to gravity right now? Yeah, exactly, and we'll
5:23
Speaker 1: be talking exactly about what that means. And we've touched
5:26
Speaker 1: on this a few times, but this is the scenario
5:28
Speaker 1: where a particle exists theoretically and it's already been given
5:32
Speaker 1: a name before it's discovered. If some particles we find them,
5:36
Speaker 1: then we argue about how to name it. Right, some
5:39
Speaker 1: particles are named before they're discovered, like we have the
5:43
Speaker 1: idea for them, and then we go ahead and find it.
5:45
Speaker 1: We already know what to call it, like the Higgs boson.
5:48
Speaker 1: So let's say your physicist and you think of something
5:50
Speaker 1: on the on your notepad, or you find something. Do
5:54
Speaker 1: you think most physicists have sort of a pre name
5:57
Speaker 1: in their minds when they're looking for these things, or
5:59
Speaker 1: even if they're I don't think they're looking for these things.
6:02
Speaker 1: I don't know. Um, but I haven't noticed recently there
6:04
Speaker 1: are a lot more names being given to ideas. I
6:07
Speaker 1: think this is, you know, young people coming up and
6:10
Speaker 1: recognizing the value of branding, and so every sort of
6:14
Speaker 1: new idea that something that comes up with has like
6:16
Speaker 1: a slick sounding name that's associated with it so that
6:19
Speaker 1: it sticks in people's heads. It's not just some complicated
6:22
Speaker 1: new idea, you know, it's it's it's got some branding
6:26
Speaker 1: to it. Cool. Um, But of course I've already thought
6:29
Speaker 1: about the name of a particle I would discover. Oh yeah,
6:31
Speaker 1: I mean my last name ends with S O N.
6:34
Speaker 1: So it's very clearly I got to call it the
6:36
Speaker 1: White Song. I know, you would have to call it
6:38
Speaker 1: the whites some ton. That sounds like some complicated Icelandic person. Cool.
6:45
Speaker 1: So today we'll be talking about what is the graviton
6:48
Speaker 1: and does it exist? And what does it mean if
6:50
Speaker 1: we ever actually find this particle? Right, and how would
6:54
Speaker 1: we look for it and what would it mean? Yeah,
6:56
Speaker 1: so it sounds like something either out of a Transformers
6:58
Speaker 1: movie or some thing out of a physics textbook. But
7:01
Speaker 1: we were wondering, as usual, how many people out there
7:05
Speaker 1: know what a graviton is. So I walked around wherever
7:08
Speaker 1: I was in the world, and I asked people what
7:10
Speaker 1: they knew about the graviton. Could they explain it? Did
7:13
Speaker 1: they have any idea? Had they heard it before? Did
7:15
Speaker 1: they play with one when they were a kid. So
7:17
Speaker 1: before you listen to these, think about it for a second.
7:19
Speaker 1: If you were approached by a physicist at an airport
7:21
Speaker 1: in London, what would you answer to the question what
7:25
Speaker 1: is a graviton? Here? It's what people had to say.
7:28
Speaker 1: I heard of it, but I don't know it. It's problem.
7:33
Speaker 1: But you know grav with you? Yeah, okay, I heard
7:38
Speaker 1: about gravity, but I don't I've ever heard about a
7:43
Speaker 1: material like graviton. No. Gravitons, Yes, they're the theoretical particle
7:48
Speaker 1: that is used to describe gravitate gravity's effects something gravitron
7:56
Speaker 1: grabt oh because the two were in distinction to me.
8:00
Speaker 1: All Right, I like these answers. There's some creative ones there. Um,
8:05
Speaker 1: there's one that I don't really understand. Like there's a
8:07
Speaker 1: guy talking about the gravittron. What is a gravitron. I
8:11
Speaker 1: don't even know. He was confused. He was like, wait
8:14
Speaker 1: a minute, do you mean the graviton or the gravittron.
8:17
Speaker 1: I know, but he's referring to something he's familiar with
8:20
Speaker 1: called the gravitron, and I don't even know what that is.
8:22
Speaker 1: Like it sounds like a machine he can use to
8:25
Speaker 1: control gravity or something, you know, the gravitonator. You know,
8:28
Speaker 1: it does sound kind of more physical, See, doesn't it
8:31
Speaker 1: gravitron like like that, Like it's a machine that makes
8:36
Speaker 1: hypes and it's hissing and you know, the steam coming
8:38
Speaker 1: out the side of it or whatever. It's like a
8:39
Speaker 1: steampunk gravity accelerator. All right, Well, before I feel like
8:43
Speaker 1: we people feel like we're making fun of our listeners. Um,
8:46
Speaker 1: I have to admit that I didn't know what a
8:48
Speaker 1: graviton was until basically I started talking to you only
8:52
Speaker 1: a few years ago. Oh yeah. If I had asked
8:54
Speaker 1: you a few years ago, you might have said it
8:56
Speaker 1: was some like new sleep kitchen appliance or something, and
9:00
Speaker 1: said I would have said it was a transformer problem.
9:03
Speaker 1: Most likely, it's probably the transformer. Guys were bummed if
9:07
Speaker 1: they can't name a transformer the graviton because the name
9:10
Speaker 1: is taking my physics. Oh, I don't think that's ever
9:12
Speaker 1: stopped toy companies, you know, Hold on, are you saying
9:17
Speaker 1: that these big toy companies don't have a particle physicist
9:20
Speaker 1: like on retainer for consulting. I would be surprised if
9:22
Speaker 1: they had a roboticist in their robotic robot department there.
9:27
Speaker 1: Do you have robotic criticisms of the science behind transformers,
9:30
Speaker 1: like no, that joint would work differently, or it should
9:33
Speaker 1: fold in this other way or something. You know, you
9:35
Speaker 1: have a pet pis about movies that feature physics. That's
9:39
Speaker 1: that's how robodies. This feel about every movie or anything
9:43
Speaker 1: that has robots in it. Wow, well I never even like, what,
9:46
Speaker 1: how could that possibly have the right you know, energy
9:49
Speaker 1: density output? You need a different kind of cable for that.
9:52
Speaker 1: Come on, people, But all good answers and all all
9:58
Speaker 1: good um ways to look at the universe. Yeah, and
10:01
Speaker 1: as usual, I'm grateful to those random folks out there
10:04
Speaker 1: who are totally willing to talk to a scruffy looking
10:06
Speaker 1: scientist about strange, random science questions. So kudos to anybody
10:11
Speaker 1: out there who's willing to answer science questions with no googling.
10:14
Speaker 1: That's right, I certainly would run away from you as
10:18
Speaker 1: fast as I could. Don't say hypothetical like that's happened. Well,
10:21
Speaker 1: this is a perfect point to take a break. Well,
10:37
Speaker 1: let's let's get into it. Daniel, step us through here.
10:39
Speaker 1: What is a graviton? Like, if if you had to
10:43
Speaker 1: name it in one sentence, what would it be a graviton? Basically,
10:46
Speaker 1: if you have to describe it in one sentence, what
10:48
Speaker 1: would that sentence be? How long can this sentence be?
10:50
Speaker 1: And I just keep going on and on like James
10:51
Speaker 1: Joy's class one class or maybe two classes. But you know,
10:56
Speaker 1: all right, Um, A graviton is the particle that trend
11:00
Speaker 1: smits gravity. In theory, if there is a particle that
11:04
Speaker 1: transmits gravity, so the force of gravity, the idea is
11:08
Speaker 1: that it transmits its force. It's forcing us, I guess,
11:13
Speaker 1: through a particle. And if that exists, that particles called
11:16
Speaker 1: the graviton. Exactly, that's the idea. And you can imagine,
11:20
Speaker 1: like you know, gravitational fields have to somehow transmit information
11:25
Speaker 1: like if the sun disappeared, right then we wouldn't feel
11:29
Speaker 1: the fact that the sun has disappeared until that information
11:32
Speaker 1: gets to us. Right, gravitational fields are not instantaneous. Otherwise
11:37
Speaker 1: you could build a machine to send information fast in
11:39
Speaker 1: the speed of light by wiggling rocks or something. Okay,
11:43
Speaker 1: so forces are not instantaneous. Yeah, and so sometimes it
11:47
Speaker 1: would have been weird, doesn't it get from the Sun
11:49
Speaker 1: to the Earth. So like the I know, the light
11:51
Speaker 1: has to travel at the speed of light, but you're saying,
11:54
Speaker 1: like even the force between two magnets has to travel
11:58
Speaker 1: at the speed of light. Yeah. Nothing, No information at
12:01
Speaker 1: all can travel faster than the speed of light. And
12:03
Speaker 1: then includes information about fields fields that generate forces like
12:07
Speaker 1: gravitational field or magnetic fields or something. Right. In fact,
12:10
Speaker 1: that's the way you make light. You can like wiggle
12:13
Speaker 1: charged particles and they will make light. They will shoot
12:15
Speaker 1: off photons. All right, So a granton is the particle
12:19
Speaker 1: that transmits the force of gravity. Uh yeah, And and
12:24
Speaker 1: is that weird that a force is transmitted by a particle.
12:27
Speaker 1: It's not weird at all. In fact, it's sort of
12:30
Speaker 1: a natural concept because every other force that we've ever
12:34
Speaker 1: seen has a particle associated with it, the particle that
12:37
Speaker 1: transmits the information for that force, like electromagnetism has photons right. Well,
12:42
Speaker 1: the other forces, like the weak nuclear force, it has
12:45
Speaker 1: three particles to do its bidding, the W plus, the
12:49
Speaker 1: W minus, and the Z. The strong nuclear force has
12:52
Speaker 1: the gluon. Actually there's eight of them, right, And so
12:55
Speaker 1: we have these forces electromagnetism, the weak force, and the
12:58
Speaker 1: strong force, and for those we have good quantum theories.
13:02
Speaker 1: Those quantum theories describe these particles that transmit the information.
13:05
Speaker 1: So now we have gravity. We're like, well, cong gravity,
13:09
Speaker 1: do the same thing, like, how does gravity transmit its
13:12
Speaker 1: force or its power? Exactly? That's the question is how
13:16
Speaker 1: is information transmitted for gravity? Right? In Newton's theory. Newton's
13:20
Speaker 1: original theory, he thought it was instantaneous, right. He thought
13:23
Speaker 1: if the Sun disappeared or went away or was wiggled,
13:27
Speaker 1: that we would feel that instantly. Right. But this was
13:29
Speaker 1: before the advent of relativity. At the instant that Sun disappeared,
13:33
Speaker 1: the Earth would start to crean out of control and
13:36
Speaker 1: shoot out into space. That's right, that's Newton's idea. Then
13:40
Speaker 1: Einstein comes along and he gives us general relativity and
13:43
Speaker 1: special relativity, and that tells us that information cannot be
13:45
Speaker 1: transmitted faster than the speed of light, right, And so if,
13:51
Speaker 1: for example, you change a gravitational field right, then that
13:55
Speaker 1: information propagates through the gravitational field right at the speed
13:59
Speaker 1: of light like a shock wave. Kind of exactly like
14:02
Speaker 1: a shock wave. But here's the thing. What we're talking about, right,
14:05
Speaker 1: there is a gravitational wave. Right. Like if you turn
14:10
Speaker 1: on a flashlight and you send out a beam of light,
14:13
Speaker 1: then you're sending out electromagnetic waves. Right. If you wiggle
14:17
Speaker 1: the sun, you can wiggle a black hole, then you're
14:19
Speaker 1: gonna make gravitational waves. Those are not the same thing
14:22
Speaker 1: as a graviton. They're not They're not. No, a graviton
14:27
Speaker 1: is two gravitational waves what photons are to a beam
14:31
Speaker 1: of light. I remember that general relativity describes the universe
14:35
Speaker 1: really really well. But we think that the universe is
14:39
Speaker 1: quantum mechanical. We think for the universe is is made
14:42
Speaker 1: up of little bits. And in the same way that
14:44
Speaker 1: a beam of light turns out to be made up
14:46
Speaker 1: of tiny little photons. The idea is maybe gravity and
14:51
Speaker 1: gravitational waves are made up of tiny little gravitons. It
14:55
Speaker 1: sounds like the days that, like, right now, I'm sitting
14:57
Speaker 1: here in my studio and I'm being pulled down owned
15:00
Speaker 1: by gravity towards the center of the Earth. And you're
15:03
Speaker 1: saying that that somehow, being like, somehow the Earth is
15:06
Speaker 1: shooting gravitons at me, or it's or I'm shooting gravitons
15:09
Speaker 1: at the Earth. But what does that mean for for me, Daniel,
15:12
Speaker 1: for my universe? I think the important thing to think
15:15
Speaker 1: about is how fields change. So the Earth. If the
15:19
Speaker 1: Earth is not moving right relative to you, then you
15:22
Speaker 1: have a constant gravitational field and so there are no
15:24
Speaker 1: gravitational waves being propagated there and um, so you don't
15:28
Speaker 1: need to build it out of any gravitons. But if
15:32
Speaker 1: the Earth changes, right, then that information comes as a
15:35
Speaker 1: gravitational wave, which is built out of gravitons. I see, so,
15:39
Speaker 1: and then if I see, if I stand up, you're saying,
15:41
Speaker 1: then there's some gravitons exchange between my my, my behind
15:46
Speaker 1: and the center of the Earth. I really wanted to
15:48
Speaker 1: get through a whole podcast without talking about your behind,
15:51
Speaker 1: but all right, let's do it. Yes, exactly, because remember
15:55
Speaker 1: that the Earth is pulling on you, right, and you
15:58
Speaker 1: are also pulling on the Earth with the same force. Right. Um.
16:02
Speaker 1: One way I heard somebody say, cleverly, is that like,
16:05
Speaker 1: on the surface of the Earth, you weigh I don't
16:07
Speaker 1: know what a hundred fifty pounds, right, but on the
16:09
Speaker 1: surface of the of Jorge, the Earth weighs a hundred
16:12
Speaker 1: and fifty pounds. There's a force of attraction between you
16:16
Speaker 1: and the Earth, and anytime that changes, you're gonna need
16:18
Speaker 1: gravitational little gravitational waves made out of even smaller gravitons.
16:24
Speaker 1: And the whole idea is just an extrapolation from the
16:26
Speaker 1: other fields. Right. We see that it happens for electromagnetism,
16:30
Speaker 1: We see that it happens for the weak force and
16:32
Speaker 1: the strong force, and so we like patterns. We'd like
16:34
Speaker 1: to say, maybe this is really a deep thing and
16:37
Speaker 1: if it. If so, why doesn't it also apply to gravity? Okay,
16:41
Speaker 1: so if I stand up, then are there gravitons exchanged
16:44
Speaker 1: between me and the Earth? Is that kind of what
16:46
Speaker 1: you're saying, is like it's about the changes in the
16:49
Speaker 1: gravitational fields. Yeah, exactly. Um, information about the gravitational field
16:55
Speaker 1: can be conveyed, and we think that it's probably made up,
16:58
Speaker 1: but it's sort of the microscopic level of gravitons, right,
17:02
Speaker 1: They are the basic quanta the same way that we
17:06
Speaker 1: you know, we think that light. We know that light
17:08
Speaker 1: is made out of tiny little bits we call photons. Right.
17:11
Speaker 1: We think that all gravitational information is built out of
17:14
Speaker 1: tiny little bits called gravitons. But of course we've never
17:17
Speaker 1: seen them. It's just theoretical. It's it's purely a concept
17:21
Speaker 1: extrapolated from other examples, right, because I think a lot
17:24
Speaker 1: of people maybe forget that it's not just light that's
17:26
Speaker 1: made out of photons. It's just it's the electromagnetic force itself, right,
17:31
Speaker 1: like between two magnets when you're when they're pulling or
17:35
Speaker 1: pushing each other, they're shooting each other with photons, right
17:38
Speaker 1: in some ways, yeah, exactly. And remember a photon is
17:41
Speaker 1: just like a ripple in some quantum field. These days,
17:45
Speaker 1: we don't think about the basic thing in the universe
17:47
Speaker 1: is being particles. Right. You probably have an image in
17:49
Speaker 1: your mind of like two particles pushing each other by
17:52
Speaker 1: shooting them each other with little laser guns or something. Right,
17:55
Speaker 1: instead think about paint pong balls. Maybe this is microscopic, right,
18:00
Speaker 1: So instead think about like two particles on our waterbed, right,
18:04
Speaker 1: and every time one of the moves it affects the
18:07
Speaker 1: other one. That's like it ripples over to the other one.
18:09
Speaker 1: And those ripples are ripples in the photonic quantum field, right,
18:14
Speaker 1: and those are what we call photons. We reimagine these
18:18
Speaker 1: particles as ripples in these sort of base, more base objects,
18:22
Speaker 1: these deeper and more fundamental objects called quantum fields. And
18:25
Speaker 1: a big part of the theory is that these ripples
18:28
Speaker 1: have a minimum size, right, Like, you can't have an
18:30
Speaker 1: infinitely small ripple. At some point they sort of like
18:34
Speaker 1: become chunky too, like exactly. Then that's where Einstein, you
18:38
Speaker 1: sort of ran up against the wall. Right. Einstein correctly
18:41
Speaker 1: predicts that gravity takes time to propagate. For example, his
18:45
Speaker 1: his theory has gravitational waves in it, and we've seen them, right,
18:48
Speaker 1: that's awesome. But what we don't know is if those
18:51
Speaker 1: waves are made of tiny little bits, like if you
18:53
Speaker 1: zoom in on them enough and you break them down
18:56
Speaker 1: into tiny little bits, like if you turn down a
18:58
Speaker 1: flashlight really really low. Eventually, if you have a really
19:02
Speaker 1: awesome flashlight, you'll get it down to the point where
19:04
Speaker 1: it's sending out one photon at a time. Right, there's
19:07
Speaker 1: a minimum amount of energy that has to come out
19:10
Speaker 1: of your flashlights, either off or sending out one photon
19:12
Speaker 1: per second. I can't send out half a photon. And
19:15
Speaker 1: so it is that there's maybe a minimum amount of gravity,
19:20
Speaker 1: and that's what a graviton is. Yeah, exactly. You know,
19:23
Speaker 1: think about it maybe spatially if that's helpful. Like, you know,
19:26
Speaker 1: the universe has pixels, right, we talked about space maybe
19:28
Speaker 1: being sliced up into little pixels. Well, this is sort
19:31
Speaker 1: of like pixelization of gravity, Like is there a minimum
19:33
Speaker 1: bit of gravity? And you know, we don't know. There's
19:37
Speaker 1: a very strong argument that there should be because everything
19:40
Speaker 1: else in the universe seems to be quantum mechanical. Right.
19:43
Speaker 1: The universe, as as you like to say, is chunky
19:46
Speaker 1: and a creamy peanut butter, right, and so we think
19:49
Speaker 1: everything should behave those rules. But our theory of gravity
19:53
Speaker 1: general relativity is not a quantum theory, right, It's a
19:56
Speaker 1: classical theory. It assumes that you could have an infinitely
20:00
Speaker 1: tiny amount of gravity, or that you can have mass
20:02
Speaker 1: in an infinite amount in a tiny little dot right
20:05
Speaker 1: of singularity. Those things are are at odds with quantum mechanics. Yeah,
20:09
Speaker 1: because the difference I think you've told me this before,
20:11
Speaker 1: is that you know, all the other forces act via
20:16
Speaker 1: quantum field, but we don't know if gravity has a
20:21
Speaker 1: gravity field in the universe, right, Like gravity kind of
20:25
Speaker 1: has a special place among the other forces, and that
20:27
Speaker 1: it's more like a bending of time and space exactly.
20:30
Speaker 1: But we hate special cases, right, Physicists like to generalize,
20:34
Speaker 1: We like to see patterns. We like to organize everything together.
20:38
Speaker 1: So to say, like everything works this way except for gravity.
20:41
Speaker 1: Things run in this certain manner except for gravity. You
20:44
Speaker 1: think nobody special. Well, it's something is special. Then it's
20:48
Speaker 1: a clue. Right, So it's a clue that about how
20:50
Speaker 1: the universe works at some really interesting, deep fundamental level.
20:53
Speaker 1: So before we believe that, we'd like to remove all
20:56
Speaker 1: other possible explanations. And it's a pretty an argument that
21:00
Speaker 1: every other force we've ever seen is a quantum force
21:03
Speaker 1: can be described in terms of particles and fields. So
21:06
Speaker 1: we're going to try really hard to make that work.
21:09
Speaker 1: Also for gravity, before we declare that it's impossible. Gravity
21:13
Speaker 1: special because you can think of it as a bending
21:15
Speaker 1: of space and time, whereas all the other forces you
21:17
Speaker 1: can't think of them as a bending of space and time. Right,
21:20
Speaker 1: like they the the way that it makes sense to
21:23
Speaker 1: think about those forces is quantum physics. But the way
21:25
Speaker 1: it makes sense to think about gravity is as a
21:27
Speaker 1: bending of space and time. And so that's that's kind
21:30
Speaker 1: of the problem, isn't it. That is a problem. But
21:32
Speaker 1: like everything in physics, you can describe in multiple ways,
21:35
Speaker 1: and so you can build up a theory of gravity
21:38
Speaker 1: that comes from particles and fields. Right, you can start
21:41
Speaker 1: with a gravitational field, right, a quantum field, and you
21:45
Speaker 1: can have gravitons zipping around, and then you can say, well,
21:48
Speaker 1: can I build that? Can I sort of build this
21:51
Speaker 1: mental model and can I have it predict the same
21:55
Speaker 1: things that general relativity predicts? Right? Because general relativity very successful,
21:59
Speaker 1: that description gravity works really well. But can I get
22:03
Speaker 1: the same description building it up in another way? And
22:06
Speaker 1: that's sort of the theoretical challenge, And so far the
22:09
Speaker 1: answer is no. Like they have not yet been able
22:11
Speaker 1: to build a theory of gravity that starts from quantum
22:15
Speaker 1: bits and explains all the same stuff as Einstein's theory.
22:18
Speaker 1: They haven't because it just doesn't work. They just cannot
22:21
Speaker 1: make it work. Like they put a theory together using
22:24
Speaker 1: the same strategies as they have for electromagnetism and the
22:27
Speaker 1: weak force and the strong force, and it just doesn't work.
22:29
Speaker 1: It gives nonsense answers, like it says, if you do
22:33
Speaker 1: this experiment, then you will measure infinity mass or you
22:36
Speaker 1: will build be an infinite amount of energy released, which
22:39
Speaker 1: is nonsense. Right, You can't have an infinite amount of energy,
22:42
Speaker 1: So it predicts things which cannot be true, which just
22:45
Speaker 1: means that we have a problem with the calculation, you know,
22:47
Speaker 1: and we had similar problems with every other quantum field theory,
22:51
Speaker 1: but we figured them out. But what is it about
22:53
Speaker 1: gravity in particular? You think that is giving you so
22:56
Speaker 1: much trouble? Gravity has this weird feature that it gets
22:59
Speaker 1: stronger when there's more energy, right, because gravity essentially is
23:03
Speaker 1: the bending of space due to energy, right, that's the
23:06
Speaker 1: way we like to think about it. So as the
23:08
Speaker 1: energy goes up, then you get stronger gravity, and then
23:11
Speaker 1: because you have stronger gravity, the energy has gone up,
23:14
Speaker 1: and so you get this feedback effect where these infinities
23:16
Speaker 1: crop up much more easily than in other forces, because,
23:20
Speaker 1: like electromagnetism doesn't get stronger when you have more energy,
23:24
Speaker 1: So it's kind of like um, it's more tied into
23:27
Speaker 1: the very nature of the universe maybe, and so it
23:30
Speaker 1: doesn't quite work, that's right. And if it is a
23:32
Speaker 1: quantum field, and if it does have a quantum particle,
23:35
Speaker 1: it will still be different. It will still be unique.
23:37
Speaker 1: Like the graviton. We think it has this weird kind
23:41
Speaker 1: of way of spinning, like all the other particles that
23:44
Speaker 1: transmit forces that have either spin one or spin zero.
23:48
Speaker 1: But the graviton, the only way people have even become
23:50
Speaker 1: close to making it work is having it have a
23:53
Speaker 1: lot more ways to spin, so it's spin two, which
23:56
Speaker 1: means there's five different ways it can spin instead of
23:58
Speaker 1: just one way three ways. So it would definitely be
24:02
Speaker 1: a different beast if we if we were able to
24:04
Speaker 1: make a quantum theory of gravity, it would not look
24:07
Speaker 1: that similar to like the strong force or the weak
24:10
Speaker 1: force or electromagnetism. You have to kind of give it
24:12
Speaker 1: a few more bells and whistles, and that's just to
24:15
Speaker 1: try to make it work right, And even still those
24:17
Speaker 1: theories don't work. The only theory of quantum gravity that
24:20
Speaker 1: works at all is one that starts very very basic, right,
24:24
Speaker 1: like string theory and loop quantum gravity. These are attempts
24:28
Speaker 1: to start from a very different place and build up
24:30
Speaker 1: quantum fields themselves. And they have succeeded in making some
24:35
Speaker 1: useful theories of quantum gravity, but none that we can
24:37
Speaker 1: test yet. What would it mean if it is, if
24:39
Speaker 1: the graviton does exist and it is true? Right, it
24:42
Speaker 1: would mean that the bending of space and time is
24:45
Speaker 1: like you said, pixelated or chunky, or you know you can.
24:49
Speaker 1: I can't bend space and time perfectly smoothly, and it's
24:52
Speaker 1: sort of kinks. There's a knob there and instead of
24:54
Speaker 1: rotating smoothly that has little divots right at one or
24:57
Speaker 1: two or three you can't have you can't turn to
25:00
Speaker 1: two and a half. Right. But also, I think it
25:02
Speaker 1: would mean something much deeper, Right, It would mean that
25:04
Speaker 1: gravity really is a force the way we think about
25:07
Speaker 1: the other forces. We're trying to squeeze gravity into this mold.
25:11
Speaker 1: Can we describe it using the same mathematical tools we've
25:14
Speaker 1: used for the other forces. If we can succeed, then
25:16
Speaker 1: we can say something deep about gravity, like, oh, yeah,
25:18
Speaker 1: it's just a force like the other ones. It happens
25:20
Speaker 1: to have this ability to bend space and time, which
25:23
Speaker 1: is weird and interesting. We have to ask why is that?
25:26
Speaker 1: You know? And can we connected to the other forces?
25:27
Speaker 1: But we've met a huge step forward and sort of
25:30
Speaker 1: unifying all the forces together, seeing them all as one.
25:33
Speaker 1: If we can't, then you're right, gravity is weird and special.
25:36
Speaker 1: And then we have to ask what makes it weird
25:38
Speaker 1: and special? Why does it seem so much like a
25:41
Speaker 1: force if it's not really? All right? Um, so it
25:43
Speaker 1: may or may not exist, this graviton, and it may
25:46
Speaker 1: or may not totally change our our our understanding of
25:49
Speaker 1: the whole universe. And so then I think that brings
25:52
Speaker 1: us to the question of how are we gonna result this?
25:54
Speaker 1: How are we going to find this thing or not
25:56
Speaker 1: find it or conclude that it doesn't exist. So let's
25:58
Speaker 1: get into that first. Let's take a quick break. All right,
26:14
Speaker 1: we're talking about the graviton, and we're saying that it's
26:17
Speaker 1: it's kind of the minimum little ripple that that maybe
26:20
Speaker 1: gravity acts through. That if it exists, it means gravity
26:24
Speaker 1: is like the other forces. And if it doesn't exist,
26:26
Speaker 1: it means gravity is something totally different and special. So
26:29
Speaker 1: how are how are we going to find out what
26:31
Speaker 1: the answer is? Saying, Well, there's two basic approaches. One
26:35
Speaker 1: is two sort of look for evidence of it happening already, right,
26:40
Speaker 1: And we do this in astrophysics all the time. We
26:42
Speaker 1: just say, well, let's just look at into the universe
26:44
Speaker 1: and find something crazy which reveals to us the truth.
26:48
Speaker 1: Like when we're studying dark matter, and we saw the
26:50
Speaker 1: collisions of two galactic clusters that showed us how dark
26:54
Speaker 1: matter gets separated from normal matter. So in this case,
26:57
Speaker 1: we'd be looking for like really huge gravity tational waves.
27:01
Speaker 1: So we've already seen gravitational waves, right, Those are evidence
27:05
Speaker 1: of the wiggling of a gravitational field when like black
27:08
Speaker 1: holes collide or whatever. And it's hard to see them, right,
27:11
Speaker 1: It's really difficult to see them because they're really faint,
27:14
Speaker 1: and so it's even harder to see whether they're made
27:17
Speaker 1: of little bits or not. Right, Like, we can just
27:19
Speaker 1: barely see them, so it's hard to tell if they're
27:22
Speaker 1: what they're made out of. So what you need to
27:24
Speaker 1: do is spot like a really mondo gravitational wave, one
27:29
Speaker 1: that was big enough that you could sort of zoom
27:31
Speaker 1: in on it and see what is made out of
27:34
Speaker 1: something really big, like a like a mega tron. I
27:38
Speaker 1: think I call it a gravitron. Nader or something, so
27:44
Speaker 1: so you need to find It's so the gravitas they
27:46
Speaker 1: exists are so small and weak you can't just like
27:49
Speaker 1: measure them with your finger, right, You're saying, we need
27:51
Speaker 1: to find something really crazy happening in the universe where
27:56
Speaker 1: that's producing so many of these and such an amount
27:59
Speaker 1: that then you can notice them. Yeah exactly. That's one strategy.
28:02
Speaker 1: The other strategy is to try to make them here
28:05
Speaker 1: on Earth. And you know the go to place for
28:08
Speaker 1: making crazy stuff here on Earth, of course, is the
28:10
Speaker 1: particle collider. Like you want to make something new, something
28:14
Speaker 1: you're not sure as possible, just keep smashing particles together
28:18
Speaker 1: and eventually it will come out. And so you're saying,
28:20
Speaker 1: one way to maybe study graviton is to make gravitons. Yeah, exactly.
28:24
Speaker 1: And that's the magic of a particle collider is you
28:27
Speaker 1: throw stuff together and if something can exist, then you
28:30
Speaker 1: will see it. And so if we smash protons together
28:34
Speaker 1: often enough, and gravitons are a thing, that eventually those
28:38
Speaker 1: two protons one a trillion or one or the quadrillion
28:42
Speaker 1: collisions will turn into a graviton, and that graviton will
28:45
Speaker 1: then turn into something else that we can see. Hold
28:47
Speaker 1: on a second, Daniel, here, you're saying that at the
28:51
Speaker 1: particle collider, you're taking protons, smashing them together and then
28:55
Speaker 1: transforming them into gravitons. We want to, we're open to
28:59
Speaker 1: that would be come true. So far, no, so so
29:02
Speaker 1: a graviton is a transformer if you find it's what
29:06
Speaker 1: I'm saying, I totally walked into that. It's exactly. Or
29:09
Speaker 1: the particle collider is the transformer because it transforms protons
29:13
Speaker 1: into other kinds of stuff. But you know there's a
29:15
Speaker 1: huge difference. They're transformer when it changes. It's all the
29:19
Speaker 1: same stuff, just rearranged in a different shape. Right. The
29:22
Speaker 1: dinosaur is actually the robot, just with the head where
29:25
Speaker 1: the tail is or whatever. But in this case, we're
29:28
Speaker 1: not doing that or not. We're not rearranging what's inside
29:30
Speaker 1: the proton into a different shape to make a graviton.
29:34
Speaker 1: The proton and nilin it turns into nothing. It turns
29:37
Speaker 1: into raw energy, which that can then be turned into
29:39
Speaker 1: something new. That's how exactly you explore the universe by
29:42
Speaker 1: turning this raw energy into any of the stuff that
29:45
Speaker 1: he can turn into. So it's more like alchemy than transformation.
29:51
Speaker 1: That's uh, and those are totally different for sure. Yeah, exactly.
29:55
Speaker 1: If gravitons exist, then the idea is we could make
29:58
Speaker 1: them by colliding proton together. Eventually, one out of a
30:02
Speaker 1: jillion times we would make them, and then we would
30:04
Speaker 1: see them turn into other particles like a pair of electrons. Right. Essentially,
30:08
Speaker 1: a graviton would look sort of like another version of
30:11
Speaker 1: the photon. Would you be able to see it though?
30:13
Speaker 1: Wouldn't it be so weak and small that you be
30:16
Speaker 1: very very very very difficult to see. Well, that's the
30:19
Speaker 1: cool thing about the collider, right, I feel like I'm
30:21
Speaker 1: a collider evangelist today, is that things that are really
30:24
Speaker 1: weak that are hard to see just turned into things
30:27
Speaker 1: that are really rare at the collider. And so the
30:29
Speaker 1: more collisions you make, the more you can see rare
30:32
Speaker 1: stuff like yeah, it's weak, which means every time a
30:35
Speaker 1: proton collides, you've got to roll a like trillion sided
30:38
Speaker 1: die to figure out what's going to happen, and only
30:41
Speaker 1: one of those sides says a graviton is made. But
30:44
Speaker 1: that's cool. If you roll the die at trillion times
30:46
Speaker 1: a day, then you're probably gonna get a graviton a day,
30:49
Speaker 1: So it sort of sounds like you're basically looking for
30:51
Speaker 1: effects that you can point to and say, hey, that
30:54
Speaker 1: means that there's a graviton somewhere in there, like when
30:58
Speaker 1: two black holes collide or when you smash these protons together. Exactly.
31:02
Speaker 1: That's what we do with colliders. We look for unique
31:04
Speaker 1: signatures of new particles, something that says, oh, this has
31:08
Speaker 1: to be a new particle. It's very likely to be
31:10
Speaker 1: a new particle that can't be explained in any other way.
31:13
Speaker 1: And so we have theories of how gravitons would look
31:15
Speaker 1: in our detectors, and so we're looking for them. Um.
31:18
Speaker 1: So far, we haven't found a hint of gravitons and
31:21
Speaker 1: our detectors, um, which just means that you know, they're
31:24
Speaker 1: basically smaller than we can see. Um, so we could
31:28
Speaker 1: just keep looking. What you said, you haven't seen a
31:30
Speaker 1: hint of them, so like zero zero nothing. Yeah, exactly.
31:35
Speaker 1: What we've seen so far is totally consistent with Einstein's
31:38
Speaker 1: theory of general relativity. Well, what do you think is
31:40
Speaker 1: more more likely, just in your personal opinion, do you
31:43
Speaker 1: think the graviton exists or do you think maybe it doesn't.
31:46
Speaker 1: End Gravity is a very special kind of force. I
31:49
Speaker 1: think that we're going to figure out that everything is
31:51
Speaker 1: quantum mechanical. I think the quantum mechanics is just so
31:55
Speaker 1: fundamental to everything we've seen in the universe except for
31:58
Speaker 1: this one thing that it seems more likely to me
32:01
Speaker 1: that we just haven't understood that one last thing yet.
32:04
Speaker 1: Um that it's you know, it's the one thing that's
32:07
Speaker 1: has that's left over that hasn't been translated yet into
32:10
Speaker 1: modern theories of physics. Um. So that's my suspicion that
32:13
Speaker 1: everything is quantum mechanical, because if, if, if most things
32:17
Speaker 1: are quantum mechanical, it's hard to imagine how you can't
32:19
Speaker 1: have everything quantum mechanical, you know, like where's the interface
32:23
Speaker 1: between the quantum mechanical stuff and then non quantum mechanical stuff.
32:26
Speaker 1: They have to interact and so they have to both
32:28
Speaker 1: be quantum mechanical to sort of talk to each other. Yeah,
32:31
Speaker 1: so you're really hoping that it's true, because then that
32:33
Speaker 1: would be like the gravytan on your mash potatoes. No, no,
32:38
Speaker 1: I suspect it's true. I hope it's not, because it
32:42
Speaker 1: would be a huge shock if it wasn't right. And
32:44
Speaker 1: that's the best case scenario for science is learning something
32:47
Speaker 1: which is a deep shock to like the fundamental community
32:50
Speaker 1: to say, like what that's impossible. That makes us rethink everything. Awesome,
32:55
Speaker 1: that's what science is about, right, not like, yeah, we're
32:58
Speaker 1: pretty sure it's quantum mechanical and turns out it is
33:01
Speaker 1: check as much less exciting, even if I think that's
33:04
Speaker 1: most likely the reality. Well that's my personal philosophy. Aim high,
33:09
Speaker 1: but have low expectations. Well, I hope that's working for you. Well,
33:13
Speaker 1: I have expectations, so it doesn't. I won't be disappointed
33:17
Speaker 1: no matter how the gravy tastes. You're happy with it
33:20
Speaker 1: if it's made out of big lumps or tiny little gravitons.
33:23
Speaker 1: All right, So I think that we covered what a
33:24
Speaker 1: graviton is, right, Daniel, Yeah, how would you summarize it?
33:28
Speaker 1: I would say it's like gravy with fore and on
33:31
Speaker 1: top of the transformer and then mixed together with some alchemy.
33:34
Speaker 1: That's that's what I thought out of this, and then
33:37
Speaker 1: take two of those and smash them together. No, I
33:41
Speaker 1: think I think it's the idea that, um, you know,
33:43
Speaker 1: gravity as a force has to transmit in some way, right, like, um,
33:49
Speaker 1: you know, it's just it's not like an instantaneous thing,
33:51
Speaker 1: like a magical thing, so it has to transmit in
33:53
Speaker 1: some way and and possibly in a minimum way. And
33:56
Speaker 1: that's kind of what this graviton is, right, the idea
33:59
Speaker 1: that something is transmitting the force and prep you are
34:02
Speaker 1: officially a quantum physicist. All right, Well, we hope you
34:04
Speaker 1: enjoyed that. This is one of my favorite topics in
34:07
Speaker 1: physics because it's theoretical, it's experimental, it's experimentally theoretical, it's
34:12
Speaker 1: theoretically experimental. It's crazy, it's fascinating, and we don't know
34:16
Speaker 1: what the answer is. But someday humans will somedays somebody
34:19
Speaker 1: will know. Is gravity quantum mechanical or is it special? Great?
34:23
Speaker 1: Thanks for joining us, See you next time. Before you
34:33
Speaker 1: still have a question after listening to all these explanations,
34:36
Speaker 1: please drop us a line. We'd love to hear from you.
34:39
Speaker 1: You can find us at Facebook, Twitter, and Instagram at
34:42
Speaker 1: Daniel and Jorge that's one word, or email us at
34:46
Speaker 1: Feedback at Daniel and Jorge dot com. Thanks for listening,
34:49
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34:52
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