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Is the Universe a hologram? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, how many dimensions do you have? More than
0:12
Speaker 1: i'd like these days? Too many late night snacks from
0:15
Speaker 1: the fourth dimension? Yeah, or from the fridge dimension. Actually, yeah,
0:20
Speaker 1: that's like its own mini universe of deliciousness where I'm
0:24
Speaker 1: both the master and the slave. But aside from how
0:28
Speaker 1: many cookies are involved, how do you know you're a
0:31
Speaker 1: three dimensional being? I mean, I don't know. The world
0:34
Speaker 1: seems to be three dimensions. Yeah, but so does the
0:37
Speaker 1: stuff on my TV. But that's just like how your
0:39
Speaker 1: brain perceives it, all right. Well, then, if I'm just
0:42
Speaker 1: like in a two dimensional matrix, does that mean I
0:44
Speaker 1: can eat as many snacks as I want? Uh? Well,
0:47
Speaker 1: technically as if you're in a to the world, you
0:50
Speaker 1: can eat all the two these snacks you want and
0:52
Speaker 1: gain zero weight. I'll be right back. Hi. I'm Organ.
1:10
Speaker 1: I'm a cartoonist and the creator of PhD comics. Hi,
1:13
Speaker 1: I'm Daniel. I'm a particle of physicist and a professor
1:16
Speaker 1: at you see Irvine, and I enjoy any dimension snack really,
1:21
Speaker 1: even a one dimensional snack. I guess spaghetti is a
1:23
Speaker 1: one dimensional snack technically, especially the spaghettini or the angel hair. Yeah, exactly.
1:28
Speaker 1: I don't discriminate. I'm not a dimensionist. I see all
1:31
Speaker 1: dimensions as equal. So welcome for a podcast Daniel and
1:34
Speaker 1: Jorge Explain the Universe, a production of My Heart Radio
1:37
Speaker 1: in which we take a part the universe into its
1:39
Speaker 1: various dimensions, the ones that are understood and the ones
1:42
Speaker 1: that remain puzzling. We take your mind on the journey
1:46
Speaker 1: into all of those dimensions, trying to understand what we
1:49
Speaker 1: do know about the universe and what we don't. We
1:52
Speaker 1: range from the smallest of questions about the smallest of
1:55
Speaker 1: things and their color and shape and whether they spin,
1:58
Speaker 1: all the way out to the biggest and deepest and
2:01
Speaker 1: broadest of questions about the nature of the human context
2:05
Speaker 1: in this crazy and beautiful cosmos. Because it is a
2:08
Speaker 1: pretty wild universe, and we like to take you on
2:11
Speaker 1: the up and the down, on the front and the back,
2:13
Speaker 1: and the left and the right, and the and the
2:15
Speaker 1: good and the bad jokes as well. That's right. There's
2:17
Speaker 1: a lot to explore in the universe, is what I'm saying.
2:19
Speaker 1: We spend the entire dimension of humor, all the way
2:22
Speaker 1: from puns to dad jokes. Is there anything else? Aren't
2:25
Speaker 1: this in the same access or the same you know. Point,
2:29
Speaker 1: is there such a thing as a non silly death.
2:32
Speaker 1: My teenagers say that any joke I make is a
2:34
Speaker 1: dad joke. Oh, I see, you have no death, according
2:37
Speaker 1: to them. That's right, it's all one dimension. There's so humor,
2:40
Speaker 1: seems we one dimensional two because you're pretty funny, Daniel.
2:43
Speaker 1: For a physicist, I guess that's a two dimensional compliment
2:46
Speaker 1: right there. Projected onto the surface of physicists, you'll look
2:49
Speaker 1: pretty funny. But yeah, we like to explore all the
2:51
Speaker 1: big questions about the universe, what's real and possibly what's
2:55
Speaker 1: not real in this universe because this universe seems to
2:59
Speaker 1: have a lot of super crisis in store for us.
3:01
Speaker 1: That's right, We as an intelligent species have been digging
3:04
Speaker 1: into the question of the nature of reality, What is
3:08
Speaker 1: actually out there and is it different from what we perceive.
3:12
Speaker 1: We would like to know something true, something universal about
3:16
Speaker 1: the universe, not just what humans think it might be,
3:18
Speaker 1: but something we could like compare notes with aliens about right,
3:22
Speaker 1: But what if the aliens are since they're in the
3:24
Speaker 1: same universe, what if they're just as fooled as we
3:26
Speaker 1: are by this crazy kind of tricks. Their universe we
3:30
Speaker 1: live in. I believe in the wisdom of the crowd.
3:33
Speaker 1: You know, if you average over infinite intelligent races, somebody
3:36
Speaker 1: out there has kind of figured out what the universe
3:38
Speaker 1: is actually like. I don't like the idea that we've
3:41
Speaker 1: all been fooled in just the same way. And you
3:44
Speaker 1: know that from the Internet. I guess it's a good
3:46
Speaker 1: test bed for that idea. Yeah. Absolutely, On the Internet
3:48
Speaker 1: you can find every possible opinion with evidence, without evidence,
3:53
Speaker 1: it doesn't really matter. You can find all the dimensions there,
3:55
Speaker 1: you certainly can. But our goal on this podcast and
3:59
Speaker 1: as a species is to unravel the fundamental nature of
4:02
Speaker 1: the universe, to see it for what it is, and
4:05
Speaker 1: to ask the most basic questions about what it's like
4:09
Speaker 1: and its structure and its shape. Yeah, and sometimes these
4:12
Speaker 1: questions sort of make you uncomfortable, maybe Daniel as a physicist,
4:17
Speaker 1: because you know, we're sort of questioning how real is
4:19
Speaker 1: real or how real are the things that physicists think
4:22
Speaker 1: are real. That doesn't make me uncomfortable. That makes me excited.
4:26
Speaker 1: When we are on the verge of like revealing that
4:28
Speaker 1: the universe is totally different from the way that we
4:30
Speaker 1: thought it was. That we're all just you know, projections
4:33
Speaker 1: on the wall of Plato's cave. That's exciting because it
4:36
Speaker 1: means we're gonna learn something. We're going to emerge from
4:39
Speaker 1: like some shroud of ignorance and actually understand something deep
4:42
Speaker 1: and true about the universe, even if it up ends
4:45
Speaker 1: everything we thought we knew and changes the entire context
4:48
Speaker 1: of our existence. That's sort of the goal of physics.
4:51
Speaker 1: Maybe I'm just projecting here, Daniel. It makes me a
4:54
Speaker 1: little bit uncomfortable to think that everything I know is
4:56
Speaker 1: to be real is not actually real. Well, I'm pretty
4:59
Speaker 1: sure that's true. Well, they were gonna be asking a
5:02
Speaker 1: one one sort of version of this question, is the
5:04
Speaker 1: universe real? And it has to do with sort of
5:07
Speaker 1: like the dimensionality of the universe and how many dimensions
5:10
Speaker 1: it actually has, and is it different than the number
5:12
Speaker 1: of dimensions we feel and see and touch and can
5:15
Speaker 1: feel ourselves in. That's right, And we're gonna use the
5:17
Speaker 1: word dimension here, and we don't mean, you know, like
5:20
Speaker 1: the alternate dimension where everything is made out of marshmallows,
5:24
Speaker 1: or where aliens escape to as sort of a parallel universe.
5:27
Speaker 1: You see that a lot in science fiction. What we
5:29
Speaker 1: mean by dimension here really is the mathematical description of it,
5:33
Speaker 1: meaning just like a direction of possible motion. And I've
5:37
Speaker 1: always found it fascinating that our universe has three dimensions
5:41
Speaker 1: or seems to have three dimensions, because you've got to
5:44
Speaker 1: wonder like why three three is such a weird number. Yeah,
5:48
Speaker 1: So to be on the program, we'll be asking the
5:50
Speaker 1: question is the universe a hologram? Now? Daniel? Are you
5:59
Speaker 1: sure we can't just talk about the marshmallow dimension where
6:01
Speaker 1: all all the gatings are. That sounds like a pretty
6:03
Speaker 1: good podcast topic. Are the aliens made of marshmallows in
6:07
Speaker 1: that dimension or that Do they just eat marshmallows? I
6:10
Speaker 1: don't know. You tell me you're the one projecting this
6:12
Speaker 1: image into my brain. Maybe they go hunting for marshmallows.
6:15
Speaker 1: So the question is is the universe a hologram? Now?
6:18
Speaker 1: This is a pretty interesting question. Are you saying, like
6:20
Speaker 1: the whole universe where we live in is a hologram?
6:24
Speaker 1: Like an illusion? Kind of? Yeah, that's sort of the
6:26
Speaker 1: idea that maybe the universe doesn't actually have three dimensions.
6:31
Speaker 1: Maybe it's actually just the projection in our minds or
6:35
Speaker 1: in our experience of what's actually a two dimensional universe.
6:39
Speaker 1: That's sort of like feels like three dimensions that we
6:42
Speaker 1: can experience as if it was three dimensions, sort of
6:45
Speaker 1: like a hologram. Although you know, it makes the universe
6:48
Speaker 1: sound like a cheap trick and like one of those
6:50
Speaker 1: baseball cards or those little tinfoil things you put on
6:54
Speaker 1: dollar bills. Yeah, like by yourself universe sounds like a bargain.
7:00
Speaker 1: But I love these kinds of questions because they go
7:02
Speaker 1: to the very core of the nature of reality. You know,
7:05
Speaker 1: if we are wrong about the number of dimensions of space,
7:09
Speaker 1: what else are we wrong about? Maybe everything? And that
7:13
Speaker 1: might make some people uncomfortable, but it makes me excited
7:15
Speaker 1: because it means that there might be crazy, mind blowing
7:19
Speaker 1: revelations about the very nature of reality around the corner. Yeah,
7:23
Speaker 1: so this is a pretty tricky question. Is the universe
7:25
Speaker 1: a hologram? And so, as usual, we were curious how
7:28
Speaker 1: many people out there had thought about this question or
7:30
Speaker 1: have an opinion on this question. So Daniel went out
7:33
Speaker 1: there into the Internet to ask people is our universe
7:36
Speaker 1: a hologram? So thank you people of the Internet for participating.
7:41
Speaker 1: And if you are a person of the Internet and
7:43
Speaker 1: you'd like to volunteer to answer random questions. Please, It's
7:46
Speaker 1: very easy and fun and just takes a few minutes.
7:49
Speaker 1: Right to us two questions at Daniel and Jorge dot com.
7:52
Speaker 1: I think about it for a second. Do you think
7:55
Speaker 1: the universe you live in is nothing but an illusion?
7:59
Speaker 1: A hologram? Here's what people had to say. Sure, doesn't
8:02
Speaker 1: seem like it a holograph, as I understand it is
8:07
Speaker 1: just a trick of light. I don't know what hollow means.
8:11
Speaker 1: I am part of the universe and I feel like
8:13
Speaker 1: I have substance, And even if that's just a trick
8:17
Speaker 1: of my brain and I am just an image, how
8:21
Speaker 1: can a light based image create self awareness? So I'm
8:28
Speaker 1: guessing no, it could be somebody else's dream. Um, yeah,
8:34
Speaker 1: I think no. No, I don't know why. It sounds
8:38
Speaker 1: like somebody gave up and said, well, it's a holograph, man,
8:43
Speaker 1: and that's it. It's a holograph. But well, even if
8:47
Speaker 1: it's a holograph, who made it? Why? And who's paying
8:52
Speaker 1: for it? I'm not paying for that. I would say no,
8:57
Speaker 1: because a holograph is a three D display of light.
9:02
Speaker 1: So photos which are massless and as far as I
9:07
Speaker 1: can see, stuff around me and reused myself. We have
9:10
Speaker 1: mess so I find it very hard to imagine that
9:13
Speaker 1: the universe is a holograph. Of course, of course the
9:16
Speaker 1: universe is a holograph. No, I'm not sure if the
9:20
Speaker 1: universe is a holograph or not. I have heard some
9:25
Speaker 1: theory that maybe the universe is it's a two dimensional
9:30
Speaker 1: image projected onto three dimensional space or something like that.
9:34
Speaker 1: I have heard this theory, but it's been a long
9:36
Speaker 1: time and I don't quite remember how it goes. Well. Technically,
9:41
Speaker 1: a holograph, I think, is a written something that someone
9:45
Speaker 1: has written in the earned hands. Or maybe the uniograph
9:48
Speaker 1: universe is a holograph if you call God the writer
9:52
Speaker 1: of the manuscript. I'm not sure there. Maybe from our
9:55
Speaker 1: perspective on Earth, the universe actually is a holograph, for example,
10:00
Speaker 1: with bends and refracts and reflects like in many different
10:03
Speaker 1: directions depending on where you are in it a thort
10:06
Speaker 1: of the holographic principle. I can't remember exactly what that is,
10:13
Speaker 1: but I think it might be related to the modest
10:17
Speaker 1: sin A conjecture, which is that we'll assuming the universe
10:24
Speaker 1: is a d is in other words, that has negative curvature.
10:28
Speaker 1: Then everything in the universe, all the information that is
10:34
Speaker 1: important in the universe, can be represented on the surface
10:40
Speaker 1: of a boundary surrounding the entire universe. All Right, some
10:44
Speaker 1: pretty confident answers here. Some people were like, of course.
10:47
Speaker 1: Some people were like, no, I don't think so. I
10:50
Speaker 1: think what people said. It sounds very technical, Yeah, exactly.
10:55
Speaker 1: And I also like the ones that focus on the
10:58
Speaker 1: definition of a holograph M or a holograph or those
11:02
Speaker 1: two things different a holograph and a hologram. Yeah, Confusingly,
11:06
Speaker 1: the two things have almost nothing in common. Like, hologram
11:10
Speaker 1: is what we're talking about. It's a trick of light
11:13
Speaker 1: that it gives the impression of a three D volume
11:15
Speaker 1: from a two D surface. You know, this is the
11:18
Speaker 1: kind of thing you'll see on a baseball card or
11:20
Speaker 1: on a dollar bill, etcetera. A holograph is actually just
11:24
Speaker 1: like an essay written by one person in their own
11:27
Speaker 1: handwriting what I know. And then holography is the study
11:33
Speaker 1: of holograms, not the study of holographs. And the holographic
11:37
Speaker 1: principle that we're gonna be talking about today, that the
11:39
Speaker 1: universe might be a hologram is not the hologramic principle.
11:44
Speaker 1: It's the holographic principle. Oh man. That's before we even
11:47
Speaker 1: get to English units, right, because then you have to
11:50
Speaker 1: talk about the holo pounds and the hollow ounces, and
11:53
Speaker 1: then eventually you have to talk about the hollow deck,
11:55
Speaker 1: which you know, and then we get into real nurse
11:57
Speaker 1: territory exactly. This entire podcast has been nothing but an
12:01
Speaker 1: exercise of the holo deck. None of this has been real.
12:04
Speaker 1: Your whole life, we're all just you know, aiyes, in
12:08
Speaker 1: your little cosplay here, Daniel. No, I thought I was
12:11
Speaker 1: in your holo deck experience. I thought you were the
12:13
Speaker 1: real I thought I thought you were what were both eyes?
12:18
Speaker 1: Somebody over here better be real otherwise this whole thing
12:20
Speaker 1: is a bad joke. It's holograms all the way down.
12:23
Speaker 1: That's the real hologramic principle. So yeah, it seems to
12:26
Speaker 1: have a lot of definitions, and so I guess let's
12:28
Speaker 1: get down the business and let's lay it down for people, like,
12:32
Speaker 1: what is the one that we're talking about today? We're
12:34
Speaker 1: talking about holograms, right, and I guess what does that mean?
12:37
Speaker 1: That's right, we're talking about holograms, which is part of
12:40
Speaker 1: this idea of a holographic principle that the universe might
12:44
Speaker 1: be a hologram. And so again what we mean by
12:47
Speaker 1: a hologram is the projection of two dimensional surface into
12:51
Speaker 1: a three dimensional space. And that sounds fancy and mathematical,
12:55
Speaker 1: but really what we mean is something that looks like
12:58
Speaker 1: it has volume, like it's three dimensions x, y and z,
13:01
Speaker 1: but really there's only enough information for X and y
13:05
Speaker 1: that you can take all the information and volume and
13:07
Speaker 1: somehow encoded on a flat surface. And you might be
13:10
Speaker 1: familiar with. One of these things. Is something you can
13:12
Speaker 1: look at like a sheet of paper. As you change
13:15
Speaker 1: your angle, the image changes, just as if you were
13:18
Speaker 1: looking at something that had three dimensions. So we think
13:21
Speaker 1: it has three dimensions, but really it's we're just looking
13:23
Speaker 1: at a two D surface, which means that all of
13:26
Speaker 1: that sort of three D information is sort of encoded
13:31
Speaker 1: or or you know, written down in that too D
13:33
Speaker 1: piece of paper somehow exactly, because a three D object,
13:36
Speaker 1: when you look at it, you only ever see a
13:38
Speaker 1: two D slice, right, you see one side of it,
13:41
Speaker 1: or you see another side of it, or you see
13:42
Speaker 1: another side of it. So a three D object has
13:45
Speaker 1: all of those two D slices somehow encoded into it, right,
13:49
Speaker 1: And so a hologram is a two D surface with
13:52
Speaker 1: all that three D information encoded into it somehow, so
13:55
Speaker 1: that when you look at it from different angles, you
13:57
Speaker 1: see the right to D slice. So you're rain is like, oh,
14:01
Speaker 1: that's a three D object, just sort of like in
14:04
Speaker 1: Star Wars when Princess Leiah is projected out of R
14:07
Speaker 1: two D two, right, it's not just she's on a screen.
14:10
Speaker 1: It looks like she's there. And they have these all
14:12
Speaker 1: over Star Wars all the time, so they're like confusingly
14:15
Speaker 1: low tech, right, they're always like weird and flickery. Anyway,
14:18
Speaker 1: Princess Leiah says, you know, help me, Obi one, you're
14:21
Speaker 1: my only hope, And that's a hologram because it looks
14:24
Speaker 1: like she's sort of taking up physical volume rather than
14:27
Speaker 1: just printed onto a screen, right, and right now you're
14:30
Speaker 1: my only hope, Daniel, because I'm a little bit confused
14:32
Speaker 1: here because it gets tricky, right, because you're talking about
14:36
Speaker 1: Princess Leab and so she's been projected into that three
14:39
Speaker 1: D world, but we're looking at it on a flat
14:41
Speaker 1: screen and then we're looking at it through two eyeballs,
14:45
Speaker 1: which also kind of take two D pictures. So are
14:48
Speaker 1: we talking about the sort of illusion of death or
14:51
Speaker 1: are we talking about things having actual depth encoded in
14:55
Speaker 1: a two D service. We're talking about having enough information
14:58
Speaker 1: to describe of volume, but encoded on a two D surface.
15:03
Speaker 1: So hologram is when you can describe something using only
15:07
Speaker 1: two dimensions, but it has enough information to describe the
15:10
Speaker 1: full three D volume. And that's not always possible, right,
15:14
Speaker 1: It's not always possible to describe a three D object
15:17
Speaker 1: in terms of a two D surface. It depends on
15:19
Speaker 1: what you can do with that two D surface, Like
15:22
Speaker 1: how do we make holograms? How do you have those
15:25
Speaker 1: like baseball cards where it looks like the players moving
15:28
Speaker 1: as you turn it. And they do that by adding
15:30
Speaker 1: information to the two D surface, Like they have these
15:33
Speaker 1: little ridges on the surface, so that when you look
15:36
Speaker 1: at the image, you're seeing like a different part of
15:38
Speaker 1: those ridges, and they have like different images on different
15:41
Speaker 1: parts of those ridges. So they've done something to encode
15:45
Speaker 1: add information to the two D surface so that you
15:48
Speaker 1: have the whole three D thing actually printed down there
15:51
Speaker 1: on two D. Right, Because they sort of like fool
15:53
Speaker 1: your eyeballs into thinking it's three D, right, Like they
15:56
Speaker 1: give one image to one eyeball and they give another
15:58
Speaker 1: image to the other eyeball, and somehow you think it's
16:02
Speaker 1: three D. But really it's all on a two D surface,
16:05
Speaker 1: except that on that surface they sort of cleverly print
16:08
Speaker 1: thing so that it somehow delivers different information to each eye. Yeah,
16:13
Speaker 1: and different information to each eye gives you the illusion
16:15
Speaker 1: of depth. But also I think it's crucial that as
16:17
Speaker 1: your head turns in relation to the two D surface,
16:20
Speaker 1: you see a very different image. Like if you just
16:23
Speaker 1: have a picture printed on a flat piece of paper,
16:26
Speaker 1: then as your head turns, you're seeing the same picture.
16:29
Speaker 1: You're seeing it from a different angle, but you're seeing
16:31
Speaker 1: the same actual information in a hologram. As your head
16:35
Speaker 1: turns and you're looking at the two D surface from
16:38
Speaker 1: a different angle, you're actually getting a different image. The
16:41
Speaker 1: image you're seeing is changing, and just the same way
16:44
Speaker 1: it would if it were a three D object and
16:46
Speaker 1: you could like look behind it or look over its
16:49
Speaker 1: shoulder or something, and you're revealing more information. That's the
16:52
Speaker 1: experience that makes your mind think it's a three D object. Now,
16:56
Speaker 1: how did those work really quickly? Do they do they
16:58
Speaker 1: encode like the image from every possible angle or is
17:02
Speaker 1: there something more to like? You know how they use
17:04
Speaker 1: lasers and stuff like and special materials to sort of
17:06
Speaker 1: encode that three D information. There's a lot of different
17:09
Speaker 1: ways to do it. None of them are perfect. We
17:10
Speaker 1: can't do a complete, perfect hologram yet in our universe.
17:14
Speaker 1: You know, like those baseball cards, they have a little
17:17
Speaker 1: bit of an angle there. It's obviously not a three
17:19
Speaker 1: D object. That's done by having these little ridges so
17:23
Speaker 1: that when you look at it from a different angle,
17:25
Speaker 1: you actually see a different image, sort of like those
17:27
Speaker 1: billboards that change as you drive by them, because there's
17:30
Speaker 1: actually like a bunch of different pictures printed at different angles.
17:33
Speaker 1: And the more clever ones and more impressive ones use
17:36
Speaker 1: interference tricks. They send multiple beams of light from every
17:39
Speaker 1: point on the surface, and then where you are you
17:42
Speaker 1: get a different kind of interference from those different beams,
17:45
Speaker 1: and that's what creates the sort of illusion of three D.
17:48
Speaker 1: The dependence on your angle comes from the interference effects.
17:52
Speaker 1: All right, pretty cool, And then I guess the question is,
17:54
Speaker 1: how could our universe be a hologram? Are you saying
17:57
Speaker 1: that we're like maybe printed on its surface, is somewhere
18:00
Speaker 1: with the ridges or do you think maybe we're you know,
18:03
Speaker 1: what we think is the our three D universe is
18:05
Speaker 1: actually printed on a surface somewhere, or maybe there are
18:08
Speaker 1: everything one surface. Is that what you're saying? Yeah, that's
18:11
Speaker 1: the idea that maybe our universe can be described the
18:15
Speaker 1: three dimensions of our universe of space and time and
18:18
Speaker 1: gravity can be described by information you could put onto
18:22
Speaker 1: a two D surface. And so then that begs the question, like, well,
18:27
Speaker 1: if our universe feels like it's three D but it's
18:29
Speaker 1: equivalent to a two D universe, what's the real universe?
18:33
Speaker 1: Is the real universe two dimensions with some weird extra
18:36
Speaker 1: bits encoded onto that two dimensions? Or is it actually
18:40
Speaker 1: three dimensions? You know which one is like physically fundamentally
18:44
Speaker 1: the true universe and which one is like mathematical equivalence. Well,
18:48
Speaker 1: I guess the question here would be we're actually like
18:51
Speaker 1: a three D universe printed on a two D surface.
18:54
Speaker 1: Then like, who which which of the dimensions is fake?
18:58
Speaker 1: Do you know what I mean? Like, is up and
19:00
Speaker 1: down phase? Then somehow it's encoded in the left and right,
19:03
Speaker 1: front and back? Or how would that even like how worthy,
19:06
Speaker 1: What do you do with the extra dimension or what
19:07
Speaker 1: is Yeah, that's a great question. Well, you know, out
19:10
Speaker 1: in the depths of space, of course, every direction is
19:13
Speaker 1: the same. You could just pick a direction and it's
19:16
Speaker 1: just as good as any other direction. So it's not
19:18
Speaker 1: like up and down or left or right or back
19:20
Speaker 1: and forth really have any meaning in terms of the universe.
19:25
Speaker 1: So on that two D surface, it's not like two
19:27
Speaker 1: of our space dimensions exist and the other one is
19:30
Speaker 1: just deleted. It's some other kind of space. So like
19:33
Speaker 1: take our three dimensions X, Y, and Z. They map
19:37
Speaker 1: two two weird dimensions on that surface, called them I
19:40
Speaker 1: don't know A and B, but they're not like physical
19:43
Speaker 1: space dimensions the way we think about them. And then
19:46
Speaker 1: there's something else going on on that surface that lets
19:49
Speaker 1: you like encode Z, that lets you take that third
19:52
Speaker 1: dimension and make sure that that information is not lost.
19:56
Speaker 1: But I guess if that information is there, wouldn't it
19:58
Speaker 1: basically be and other dimension or are you saying that
20:01
Speaker 1: it's somehow encoded through some trick by the first two dimensions. No,
20:05
Speaker 1: it's basically there, and so the information is fundamentally equivalent,
20:09
Speaker 1: but it's like a different sort of structure, Like we're
20:11
Speaker 1: talking about mapping our universe, which has three dimensions and
20:15
Speaker 1: gravity and all this kind of stuff into like an
20:18
Speaker 1: abstract space something which is like where we talk about
20:21
Speaker 1: quantum field theory on that space and we talk about
20:24
Speaker 1: the relationships between points on that two dimensional surface, and
20:28
Speaker 1: so that has effectively three dimensions because it's two dimensions
20:33
Speaker 1: plus some other weird piece of information in the quantum field.
20:38
Speaker 1: There really are two different sort of visions of the universe.
20:41
Speaker 1: One is you have three dimensional space and gravity and
20:44
Speaker 1: everything moves along, and the other is that you have
20:46
Speaker 1: a two dimensional space. But then on that space is
20:49
Speaker 1: this quantum field which is capable of encoding a third dimension.
20:53
Speaker 1: All right, sounds a bit technical, so let's dig into
20:55
Speaker 1: the details of that. But first let's take a quick break.
21:11
Speaker 1: All Right, we're wondering if the universe is all it
21:14
Speaker 1: seems to be, or whether it's kind of inflated in
21:16
Speaker 1: a way, whether it's it's fooling us into thinking there
21:19
Speaker 1: it has three dimensions, but really you're saying it could
21:21
Speaker 1: have two dimensions plus like a little pocket the value
21:26
Speaker 1: or field that tells you that gives you that third
21:28
Speaker 1: extra feeling of a third dimension. Yeah, and you know,
21:31
Speaker 1: all of this goes into trying to understand what is
21:34
Speaker 1: the nature of space itself, Like what is this thing
21:37
Speaker 1: we call space? And I think that's really interesting and
21:40
Speaker 1: like historically to think about how the ancient thinkers thought
21:43
Speaker 1: about space, you know, Newton and Descartes and those folks
21:46
Speaker 1: just thought about spaces like the backdrop of the universe.
21:49
Speaker 1: It was absolute, it was fundamental. Obviously you have to
21:52
Speaker 1: have space, and everywhere in the universe has to have space.
21:55
Speaker 1: And more recently we've learned this space does weird things.
21:58
Speaker 1: It bends and wiggles, it's shakes that expands, it does
22:01
Speaker 1: all these crazy things. And now we're not even sure
22:04
Speaker 1: what space is. We talked about it on a podcast
22:07
Speaker 1: episode recently, whether it's possible to even have parts of
22:10
Speaker 1: the universe that don't have space in them, you know,
22:12
Speaker 1: a universe without space. So part of this just goes
22:15
Speaker 1: to like trying to understand what is the nature of
22:18
Speaker 1: this space, what are the rules of it? Is it
22:21
Speaker 1: really three dimensions where all those three dimensions are equivalent?
22:24
Speaker 1: Where is it actually two dimensions with one extra tricky
22:27
Speaker 1: dimension that's making us feel like it's three dimensions, and
22:30
Speaker 1: that's why these are I think are deep and important questions.
22:33
Speaker 1: It's like, maybe we think we're in you know, X,
22:35
Speaker 1: y and Z space, you know, front, back, top, down, left, right,
22:38
Speaker 1: but really we're actually in like A B space, and
22:42
Speaker 1: each point in A B space has a little special
22:44
Speaker 1: C value that maybe somehow those three things combine give
22:49
Speaker 1: us the feeling of X, Y and Z, but really
22:51
Speaker 1: it's just A and B with a little extra cy. Yeah,
22:53
Speaker 1: and that all motion, all actual physical motion, only occurs
22:57
Speaker 1: along that surface, right, that A and B value. All right,
23:00
Speaker 1: So um, let's get into why we would think that.
23:04
Speaker 1: It sounds like a pretty crazy idea. I mean, if
23:06
Speaker 1: I think about it, I'm pretty certain we are in
23:08
Speaker 1: three D space. You know, I can move up and down,
23:10
Speaker 1: left and right, front and back, and I can things
23:12
Speaker 1: when I touched them, they feel like there's three dimensional
23:15
Speaker 1: Why would we think it's not. For a long time,
23:18
Speaker 1: we did think it was three D space, and that
23:19
Speaker 1: felt pretty settled. Though. There are ideas about how the
23:22
Speaker 1: universe might have more dimensions, you know, eleven or twenty six,
23:26
Speaker 1: But this particular idea that the universe might be two
23:28
Speaker 1: D instead of having more dimensions came from the craziest
23:32
Speaker 1: thing in the universe, and so of course it came
23:34
Speaker 1: from studying black holes. And you know how on the
23:37
Speaker 1: Extreme Universe series, I'm what were saying, like, we look
23:40
Speaker 1: at the extremes of the universe because it shows us
23:42
Speaker 1: what's possible. It breaks the rules, it stretches them. That's
23:45
Speaker 1: exactly what happened here. People were looking at black holes
23:48
Speaker 1: and trying to understand, like what is on the inside
23:51
Speaker 1: of a black hole? What's it like in there? And
23:54
Speaker 1: some people have this crazy idea maybe it's not like anything.
23:58
Speaker 1: Maybe there is no inside black hole. Maybe all there
24:02
Speaker 1: is to the black hole is the event horizon. Maybe
24:04
Speaker 1: black holes are actually just two dimensions. Yeah, we've had
24:08
Speaker 1: episodes about what happens when you go inside of a
24:11
Speaker 1: black hole and what they are, and I think it
24:14
Speaker 1: is that like when something sort of goes towards a
24:17
Speaker 1: black hole, because of the way it bends space and time,
24:20
Speaker 1: it never actually goes in right, like it basically stops
24:23
Speaker 1: at the surface forever. In a way, it depends on
24:26
Speaker 1: who you ask, which is the tricky bit. So if
24:29
Speaker 1: you are watching something fall into a black hole, then
24:32
Speaker 1: as it gets closer and closer to the black hole,
24:34
Speaker 1: space is curved more and more, and then there's more
24:37
Speaker 1: and more gravitational time dilation, which is an effect where
24:41
Speaker 1: time slows down where space is curved, and so the
24:44
Speaker 1: closer you get to the black hole, the more time
24:47
Speaker 1: slows down, and so you never actually reach it. If
24:50
Speaker 1: to wait for time equals infinity to see something actually
24:53
Speaker 1: fall into a black hole, that's if you're the person
24:56
Speaker 1: on the outside watching right. If you're the person jumping
24:59
Speaker 1: into the black hole, then you don't experience any of that.
25:03
Speaker 1: And just like in relativity, your experience of time depends
25:06
Speaker 1: on who you are, where you are, and how fast
25:09
Speaker 1: you're going. And so in this case, you just fall
25:11
Speaker 1: right in, you pass through the event horizon, you head
25:13
Speaker 1: towards the singularity. And so people are wondering, like, what's
25:17
Speaker 1: going on? How can everything be smeared on the outside
25:20
Speaker 1: of the black hole and also be inside the black hole?
25:23
Speaker 1: How is that possible? You're saying, it depends on who
25:25
Speaker 1: you ask, right, Like to us on the outside and
25:28
Speaker 1: far from a black hole, hopefully things gets mirrored on
25:31
Speaker 1: the surface of the black hole the event horizon. But
25:34
Speaker 1: you're saying to the person falling in. They just fall
25:36
Speaker 1: right in, but at time infinity for us. Yeah, that's
25:39
Speaker 1: exactly right. We see them fall in only a time
25:41
Speaker 1: equals infinity. But they see themselves fall in, you know,
25:45
Speaker 1: very normally and very naturally. And these two things contradict
25:48
Speaker 1: each other, and so often in relativity you have people
25:52
Speaker 1: having different accounts of the same situation and both being correct.
25:56
Speaker 1: And that's possible in scenarios where there's like no causal
25:59
Speaker 1: link between the events, they have a timelike relationship, for example.
26:04
Speaker 1: But here it's hard to understand, you know, how the
26:06
Speaker 1: black hole actually accumulates stuff, whether there are actually are
26:09
Speaker 1: things inside the black hole. And it goes to this
26:12
Speaker 1: question of like the black hole information, right, we talked
26:16
Speaker 1: about how if you put something into a black hole,
26:19
Speaker 1: then it's information is inside the black hole, like you
26:22
Speaker 1: throw a banana in there. Where does its energy go,
26:24
Speaker 1: Where does this entropy go, where does its quantum information go?
26:28
Speaker 1: And people are trying to understand, like what happens when
26:30
Speaker 1: these black holes evaporate. Is everything actually on the surface
26:34
Speaker 1: of the black hole and so it never really fell in,
26:36
Speaker 1: and so it's information wasn't lost or was it inside
26:40
Speaker 1: the black hole actually? And when the black hole evaporates,
26:43
Speaker 1: its information is somehow lost, So it's important whether it's
26:46
Speaker 1: actually gone inside the black hole or not. And then
26:49
Speaker 1: can you still slip on the banana? Though? If it's
26:51
Speaker 1: on the surface of the black hole, that's really the
26:53
Speaker 1: important question. I mean, that's what this whole thing, because well,
26:58
Speaker 1: I mean, if you're going to do a cartoon on
26:59
Speaker 1: the surface of a black hole, you want to make
27:01
Speaker 1: it physically accurate, right, And every cartoon has got to
27:04
Speaker 1: have somebody slipping on a banana. And so I appreciate
27:07
Speaker 1: your desire here to do physically accurate black hole surface cartoons.
27:12
Speaker 1: Thank you comedy, Yeah, and then you laugh about it
27:14
Speaker 1: at the end of time. But I think what you're
27:16
Speaker 1: saying is that there's this kind of paradox, right, Like
27:18
Speaker 1: we think things splat on the surface, and but someone
27:21
Speaker 1: according to the people going in, they go inside. And
27:23
Speaker 1: so there's this kind of idea that maybe you know,
27:27
Speaker 1: once you go inside, you're just like on a to
27:29
Speaker 1: the surface of the black hole. Yeah, that was sort
27:31
Speaker 1: of the start of the puzzle, Like how do you
27:33
Speaker 1: reconcile these two things? They seem like fundamentally very different things.
27:37
Speaker 1: And hawking and this other guy, Beckenstein. We're working on
27:39
Speaker 1: this and trying to understand, like where is the information
27:42
Speaker 1: in a black hole? How does it actually work? And
27:45
Speaker 1: they were working on this one day and they were
27:46
Speaker 1: calculating how much information can be encoded inside a black hole.
27:51
Speaker 1: That we're working on these calculations of black hole entropy.
27:54
Speaker 1: Thinking about black holes is like thermodynamic objects with temperatures
27:58
Speaker 1: that really and all this stuff. And one day they
28:00
Speaker 1: arrived at this equation, and this equation told them that
28:03
Speaker 1: the amount of information inside a black hole doesn't depend
28:07
Speaker 1: on the volume of the black hole. It depends on
28:09
Speaker 1: the area of the surface of the black hole. So
28:13
Speaker 1: like it doesn't depend on the radius cube, that depends
28:16
Speaker 1: on the radius squared. And that's kind of interesting. That's
28:19
Speaker 1: the suggestion. It says, like, m the maximum information you
28:22
Speaker 1: can store in a black hole depends on the area
28:25
Speaker 1: of its surface, not on its volume. That suggests that
28:28
Speaker 1: maybe actually these are just two dimensional objects, Like a
28:32
Speaker 1: black hole is just a two dimensional object. But we
28:34
Speaker 1: see it grow, right, don't we see a growth? Doesn't
28:36
Speaker 1: that mean that it has volume to it? It could
28:39
Speaker 1: be a two dimensional object embedded in our three D world, right,
28:43
Speaker 1: Like the surface of a sphere technically is a two
28:46
Speaker 1: D object. It's embedded in a three dimensional universe that
28:49
Speaker 1: has a radius. It can move around in three dimensions,
28:53
Speaker 1: but it's actually a two D object, like an infinitely
28:55
Speaker 1: thin sheet of paper would also be a two D object.
28:58
Speaker 1: So that's where this idea of a holographic universe hologrammic
29:01
Speaker 1: hologrammic holographic principle of a holographic universe, meaning the university's
29:06
Speaker 1: a hologram. So you're saying to the black hole could
29:10
Speaker 1: be a two dimensional object in our three D world,
29:13
Speaker 1: So how do we go from there to the whole university.
29:16
Speaker 1: We didn't yet. First were trying to understand the interior
29:18
Speaker 1: of a black hole, and the first step was to think, well,
29:21
Speaker 1: maybe the interior of the black hole is a hologram, right,
29:25
Speaker 1: maybe there is no interior. So if you are that
29:27
Speaker 1: person that fell into the black hole and you think
29:30
Speaker 1: you're on the inside of the black hole, you're actually
29:32
Speaker 1: not actually still on the surface, but the whole surface
29:36
Speaker 1: of the black hole has enough information to encode what
29:40
Speaker 1: feels like a three D internal volume. So first, before
29:44
Speaker 1: we go to the whole universe, people thought maybe the
29:46
Speaker 1: two D surface of a black hole is a hologram
29:49
Speaker 1: that projects the three D interior. So then what happens
29:53
Speaker 1: is the black hole grows. The whole inside stays on
29:56
Speaker 1: the surfacen't but it grows with the black hole. Oh man,
29:58
Speaker 1: you can't think about that. You can't change the parameters.
30:01
Speaker 1: This only works for a single thing falling into a
30:04
Speaker 1: black hole. It gets much more complicated as soon as
30:07
Speaker 1: you add like something else to a black hole. You know,
30:10
Speaker 1: for example, if you throw a banana into a black hole,
30:13
Speaker 1: then in principle, it never actually enters the event horizon.
30:16
Speaker 1: It's smeared across the surface forever, right, And that's what
30:19
Speaker 1: we're talking about now. If somebody behind you throws in
30:22
Speaker 1: an apple, everything changes because that apple will now change
30:26
Speaker 1: the shape of the event horizon. The event horizon will
30:28
Speaker 1: actually grow out to meet that apple as the apple
30:31
Speaker 1: falls in, and it will absorb the banana. So it's
30:34
Speaker 1: a totally different scenario. You're now like tossing in multiple
30:37
Speaker 1: things into the black hole. Not even something we're capable
30:40
Speaker 1: of thinking about carefully, but that that is what's happening
30:43
Speaker 1: right now in the universe, right, Like black holes are
30:45
Speaker 1: constantly sucking stuff in things are constantly falling into and
30:48
Speaker 1: they're constantly growing, So why would we think that that's
30:51
Speaker 1: what's going on. Then yes, that is definitely what's happening
30:54
Speaker 1: in the universe. And we see black holes actually growing,
30:57
Speaker 1: and so we don't know what's going on there. If
30:59
Speaker 1: you're the banana and and you're like smeared across the
31:01
Speaker 1: black hole surface, and then somebody else throws in an
31:04
Speaker 1: apple and increases the size the event horizon, it increases
31:09
Speaker 1: the surface area, and now that surface area, in theory,
31:12
Speaker 1: should be capable of describing a larger internal volume. There
31:16
Speaker 1: is nothing actually inside the black hole in this picture.
31:19
Speaker 1: Inside the black hole, there's no space, there's nothing. There
31:22
Speaker 1: isn't anything in there that's not three D space that
31:24
Speaker 1: you can move around in. There's just this weird surface
31:28
Speaker 1: that has mathematically encoded onto it enough information to describe
31:32
Speaker 1: a three D space. So the banana the apple feel
31:35
Speaker 1: like they're in a normal three D space inside the
31:37
Speaker 1: black hole, but they're still smeared across the edge of it.
31:40
Speaker 1: All right. So then thinking about black holes and what
31:43
Speaker 1: happens at the surface is what sort of led us
31:45
Speaker 1: to this idea of a universe as a hologram, like,
31:48
Speaker 1: are you saying that we're a universe imprinted on the
31:51
Speaker 1: surface of a black hole, or are you saying that
31:53
Speaker 1: just thinking about black holes let us to think, like, oh,
31:56
Speaker 1: maybe the whole thing is imprinted somewhere else. Yes, exactly,
31:59
Speaker 1: this idea from black holes let us to think more
32:02
Speaker 1: carefully about the relationships between three D spaces and two
32:05
Speaker 1: D spaces. And there was a bunch of guys working
32:07
Speaker 1: on string theory, and string theory is really really difficult.
32:11
Speaker 1: It's really hard to do any sort of calculation in
32:13
Speaker 1: string theory, and sometimes when a problem is too difficult,
32:17
Speaker 1: you look for like a mathematical trick to make it easier.
32:19
Speaker 1: There's this idea that you can have a three dimensional
32:21
Speaker 1: universe encoded on a two dimensional space, and some folks
32:24
Speaker 1: realize that if you did that with string theory, it
32:27
Speaker 1: might solve some mathematical problems, like if it's too difficult
32:30
Speaker 1: to do a calculation in two dimensions, well, what if
32:33
Speaker 1: it's actually a three dimensional universe. Then you can do
32:36
Speaker 1: the calculation there. And so people were playing around with
32:39
Speaker 1: that and realizing, oh, you can play the same game
32:42
Speaker 1: not just with a black hole, but with string theory.
32:44
Speaker 1: And so maybe you can describe the entire three dimensional
32:48
Speaker 1: universe that has strings in it has a two dimensional
32:51
Speaker 1: service and that would make some calculations easier to do
32:54
Speaker 1: and other calculations actually harder to do. But they sort
32:57
Speaker 1: of projected this whole idea onto the universe. And you know,
33:01
Speaker 1: that's a really fun moment in science when you like
33:04
Speaker 1: build a tool over here and you're like, oh, this
33:06
Speaker 1: is cool. This solves this problem, and then you turn
33:08
Speaker 1: around you're like a whole lot of second, maybe I
33:10
Speaker 1: could do this to everything, you know, maybe I can
33:14
Speaker 1: make it two thirds easier, so I'll have to do
33:16
Speaker 1: as much math. Yeah, And so there was this really
33:18
Speaker 1: big important result by a guy at the Institute for
33:21
Speaker 1: Advanced Studies in Princeton, where that collection of smart folks
33:25
Speaker 1: over there called a D S c F T, which
33:27
Speaker 1: you can google if you're interested in more details about it,
33:29
Speaker 1: or maybe we'll do a podcast episode about that. But
33:32
Speaker 1: it give us this vision that maybe the entire universe
33:34
Speaker 1: can be described in terms of being a three D
33:38
Speaker 1: illusion of a two dimensional surface somewhere. All right, Well,
33:43
Speaker 1: I have two questions for this three three dimensional problem.
33:47
Speaker 1: I guess the first one is where did the third
33:50
Speaker 1: dimension go? Like how is it being encoded in this
33:52
Speaker 1: to the surface? And two could we ever tell the
33:55
Speaker 1: difference that whether or not we are in a hologram
33:58
Speaker 1: or not. So let's get into these questions, but first
34:01
Speaker 1: let's take another quick break. All right, I know here's
34:16
Speaker 1: my favorite question in these episodes. What does it all mean? Man?
34:21
Speaker 1: Like if we're actually if our three D universe is
34:23
Speaker 1: actually imprinted on it to the surface somewhere, like where
34:27
Speaker 1: did the third dimension go? Is it just an illusion?
34:29
Speaker 1: Is it actually there? You you mentioned like maybe it's
34:32
Speaker 1: encoded in some quantum fields? Can you talk more about that?
34:35
Speaker 1: Like how does how would that encode a whole dimension? Yes?
34:38
Speaker 1: So think about space, right, do you think about spaces emptiness?
34:42
Speaker 1: But we actually know that space isn't just empty, that
34:45
Speaker 1: everywhere in the universe space has these things and that
34:48
Speaker 1: we call quantum fields. And what is a quantum field? Well,
34:52
Speaker 1: it's just like a number at every point in space.
34:55
Speaker 1: For example, you know, there's the electromagnetic field and anywhere
34:59
Speaker 1: you go in the universe, so you can ask what's
35:01
Speaker 1: the strength of the electromagnetic field here, what's the strength
35:04
Speaker 1: of it over there? It's something that has like a
35:06
Speaker 1: value at every point in space, and the E M
35:09
Speaker 1: field is actually more complicated because that's more than just
35:11
Speaker 1: a value. It has like multiple values for every point
35:13
Speaker 1: in space. But that doesn't matter. So this is something
35:16
Speaker 1: which is sort of like added to space. You know.
35:19
Speaker 1: It's like if instead of just having a city with
35:22
Speaker 1: an address, where we have a house at every location.
35:25
Speaker 1: Now inside that house you have a number like how
35:28
Speaker 1: much is that house worth? Right, So that's like another
35:31
Speaker 1: piece of information at every point in space. It's encoded
35:35
Speaker 1: into this quantum field. But there's lots of quantum fields,
35:39
Speaker 1: though you're saying this like extra information is encoded in
35:42
Speaker 1: all the fields, or like there's one quantum field for
35:45
Speaker 1: basically the Z direction. Yes, there's a special quantum field,
35:48
Speaker 1: because if you just have a quantum field, you can
35:50
Speaker 1: have like arbitrary random values and that doesn't give you
35:53
Speaker 1: like a dimension. Instead, if you have a special quantum
35:57
Speaker 1: field that follows certain rules, these are called formal field theories.
36:01
Speaker 1: If you have a quantum field which looks the same
36:04
Speaker 1: if you zoom in really really close or if you
36:06
Speaker 1: zoom out really really far, if it tends to follow
36:09
Speaker 1: the same rules. But things that are zoomed in really
36:12
Speaker 1: really close don't interact very well with things that are
36:15
Speaker 1: zoomed out really really far. Then the mathematical structure of
36:19
Speaker 1: that quantum field theory has some symmetries to it which
36:22
Speaker 1: allow things to behave exactly as if there was a
36:25
Speaker 1: third dimension. Like if things that are zoomed in really
36:27
Speaker 1: really small don't interact with things that are like really
36:30
Speaker 1: zoomed out in this quantum field theory, then it's sort
36:33
Speaker 1: of like things passing by each other in that other dimension.
36:37
Speaker 1: And you know, if there's a scale that you can
36:40
Speaker 1: like zoom in and zoom out, then it's sort of
36:42
Speaker 1: like there's another direction there in this quantum field. And
36:46
Speaker 1: so this is like a way to encode something into
36:49
Speaker 1: the quantum field by adding a bunch of rules for
36:51
Speaker 1: how it behaves, and those rules essentially make it as
36:54
Speaker 1: if it was exactly like a dimension. Kind of feel
36:57
Speaker 1: like maybe you're trying to pull a fast one on
36:59
Speaker 1: your dear yor Daniel, I am, I feel like trying
37:03
Speaker 1: to You're trying to paint an illusion here. I feel
37:06
Speaker 1: like maybe you're saying that there maybe are three dimensions,
37:09
Speaker 1: but one of them you don't want to call it
37:11
Speaker 1: a dimension, you know what I mean, Like, maybe it
37:13
Speaker 1: feels like maybe it's just like a technicality about the
37:15
Speaker 1: naming of it, But if it acts and looks like
37:17
Speaker 1: a dimension, why not just call it at the nmdion.
37:21
Speaker 1: I got nothing against calling it a dimension, but it
37:23
Speaker 1: is different from the other two, right, And our program
37:26
Speaker 1: here not just on this podcast, but as humans trying
37:30
Speaker 1: to scratch out the nature of the universe, is to
37:32
Speaker 1: figure out the nature of the universe, and so if
37:34
Speaker 1: it turns out that to the dimensions are different from
37:37
Speaker 1: the third dimension, then that's quite interesting. And so we'd
37:40
Speaker 1: be fascinated to discover, for example, that our universe was
37:43
Speaker 1: actually one dimensions with like two weird projected dimensions instead
37:48
Speaker 1: of being three dimensions, or if you were like, you know,
37:50
Speaker 1: a three dimensional surface in a four dimensional space. I
37:54
Speaker 1: think I would definitely want to know that. You know,
37:56
Speaker 1: it doesn't change how you live your life necessarily, or
38:00
Speaker 1: whether you should buy insurance. Yes, definitely buy insurance, but
38:03
Speaker 1: it changes I think, our concept of the nature of reality.
38:06
Speaker 1: So I definitely want to know. Even if mathematically the
38:10
Speaker 1: two things are totally equivalent, physically, it means that one
38:14
Speaker 1: of these dimensions is not the same as the other two, right,
38:18
Speaker 1: But is it not the same in that fundamental of
38:21
Speaker 1: a way or is it just different in a sort
38:24
Speaker 1: of like notation mathematically way. No, I think it's fundamentally different,
38:28
Speaker 1: because that would mean that space itself is two dimensions.
38:31
Speaker 1: And remember one of our goals here is to understand
38:34
Speaker 1: the nature of space, and so space itself is two dimensions.
38:37
Speaker 1: But then it has these properties, you know, these properties
38:40
Speaker 1: which allowed to do things that three dimensional space would do.
38:44
Speaker 1: Then that's different from living in three dimensional space. Yeah,
38:47
Speaker 1: I feel like you're trying to pull a Pluto here
38:49
Speaker 1: on the up and down dimension or something. It's like,
38:51
Speaker 1: it's technically a dimensionoid out a dimension. It's a dwarf dimension. Yeah, exactly.
38:56
Speaker 1: But you know, some of these calculations, these string theory calculations,
38:59
Speaker 1: are harder to do in a certain number of dimensions,
39:02
Speaker 1: and they make more sense in fuel or in more dimensions.
39:05
Speaker 1: And so if the sort of fundamental theory of everything
39:09
Speaker 1: turns out to only work in two dimensions and not
39:11
Speaker 1: in three, then also sort of tells you something about
39:14
Speaker 1: the nature of the universe itself. You know, the universe
39:17
Speaker 1: pervers the two dimensional description. I mean, in theory. You
39:20
Speaker 1: could describe the universe in terms of any number of
39:22
Speaker 1: dimensions you want, but we're looking for the most compact,
39:25
Speaker 1: the simplest, the most natural description that we hope reveals
39:29
Speaker 1: not just the way we are thinking about things, but
39:32
Speaker 1: the actual structure of the physical universe outside our minds.
39:35
Speaker 1: And I guess it also sort of depends on where
39:37
Speaker 1: you define a space, right, like space. If you define
39:39
Speaker 1: space as only the two dimensions you like, then yeah,
39:42
Speaker 1: there's it's only a two the space. But if you
39:45
Speaker 1: maybe define spaces these two dimensions plus this extra you know,
39:49
Speaker 1: value of the quantum field, then you know, maybe that
39:52
Speaker 1: is what space is quote unquote hm, that's definitely what
39:55
Speaker 1: our experience of space is, right, Either space is naturally
39:59
Speaker 1: three dimensional or it's two dimensions with this extra wiggle
40:02
Speaker 1: room in it that allows us to experience it as
40:05
Speaker 1: if it was three dimensions. I mean, it sounds to
40:07
Speaker 1: me like your question is sort of like saying, isn't
40:09
Speaker 1: the hologram actually a three D object? Like, well, no,
40:12
Speaker 1: it's not really there, you know, like it really is
40:15
Speaker 1: just a two D surface baseball card. Isn't actually three dimensions?
40:20
Speaker 1: And you might say, well, it doesn't look any different
40:22
Speaker 1: if you couldn't actually tell, what would it matter? Well,
40:24
Speaker 1: it matters to me because I want to know the truth. Man,
40:27
Speaker 1: What does it all mean? All right? Well, let's get
40:29
Speaker 1: into the last question here, which is, um, how would
40:33
Speaker 1: we even tell if we are in a two D
40:35
Speaker 1: or three D universe? Right? Like, if the difference is
40:38
Speaker 1: so small or subtle or kind of sort of like, uh,
40:42
Speaker 1: you know complex, will we ever be able to, you know,
40:45
Speaker 1: devise an experiment to tell us whether we are two
40:47
Speaker 1: D or three D. Well, we're not sure, but there
40:50
Speaker 1: are some folks out there who have some really fun
40:52
Speaker 1: ideas for figuring out if we actually live on a
40:55
Speaker 1: two D surface. And the idea is that a two
40:57
Speaker 1: D surface with a projection and it's three D surface
41:00
Speaker 1: would actually be different because there would be different quantum fluctuations,
41:05
Speaker 1: Like we're talking about a quantum field generating this third dimension, right,
41:10
Speaker 1: and so we would definitely be sensitive to like the
41:12
Speaker 1: way these fields fluctuate and quantum fields fluctuate differently in
41:17
Speaker 1: two dimensions and in three dimensions. We had a whole
41:20
Speaker 1: fun podcast episode about the nature of two D objects.
41:23
Speaker 1: You should go check that out. But things move differently
41:26
Speaker 1: in two dimensions and in three dimensions, and so they
41:28
Speaker 1: fluctuate differently, and so we can see like quantum fluctuations
41:33
Speaker 1: from the very very beginning of the universe. Quantum fluctuations
41:37
Speaker 1: you normally think of like oh, this electron went left
41:39
Speaker 1: instead right, and nobody really cares that, nobody can ever
41:42
Speaker 1: see them. But in the very beginning of the universe,
41:44
Speaker 1: those fluctuations dictated like how things happened, and they got
41:47
Speaker 1: blown up into real measurable effects. So if there was
41:51
Speaker 1: a two D world, we would see different quantum fluctuations
41:54
Speaker 1: than in a three D world, and we might be
41:56
Speaker 1: able to see hints of that in remnants of the
41:59
Speaker 1: early universe, or I see because that the when the
42:01
Speaker 1: universe was born, you're saying, at the Big Bang, you know,
42:05
Speaker 1: with things were so compact and hot and small and
42:07
Speaker 1: dance that quantum fluctuations were a big deal. And so
42:11
Speaker 1: as the universe blew up. If there was actually only
42:14
Speaker 1: two dimensions, then we would see something funny going on
42:17
Speaker 1: right now instid of the universe around us. And because
42:20
Speaker 1: this bonus dimension is responsible for making the third dimension
42:23
Speaker 1: and affecting how gravity works in this three dimensional world,
42:26
Speaker 1: we should be able to see it in gravitational wave detectors. Basically,
42:31
Speaker 1: the bottom line is that if we live in a
42:33
Speaker 1: two dimensional world with a funny bonus dimension, we should
42:36
Speaker 1: be able to see a weird sort of like noise
42:39
Speaker 1: in gravitational wave detectors that you wouldn't otherwise see. This
42:42
Speaker 1: noise would be like an extra fuzz or a unique
42:45
Speaker 1: kind of fuzz that comes from the two D surface
42:49
Speaker 1: instead of being in a three D world. But I
42:51
Speaker 1: think you're saying You're not saying that there's like one
42:53
Speaker 1: dimension that's fake. You're saying that, you know what I mean, Like,
42:55
Speaker 1: it's not like Z is fake. It's more like X,
42:59
Speaker 1: Y and Z actually mapped to a B in the
43:01
Speaker 1: a little bit and something bonus called C. You want
43:04
Speaker 1: to see flat gravitational ways, for example, you would see
43:06
Speaker 1: some weird mathematical or some weird dependency on the on
43:10
Speaker 1: the gravitational waves. Yeah, exactly. The idea is if all
43:14
Speaker 1: the three dimensions are not the same, if two of
43:16
Speaker 1: them are actual dimensions and one of them is just
43:18
Speaker 1: a bonus, then there are different rules for those dimensions.
43:20
Speaker 1: And when it comes to things like quantum mechanics and so,
43:23
Speaker 1: they have different impacts on things like gravitational waves, and
43:26
Speaker 1: we should be able to see if there's like two
43:29
Speaker 1: dimensions of noise in the gravitational waves or three dimensions
43:32
Speaker 1: of quantum noise in the gravitational waves. That was the idea.
43:36
Speaker 1: At least. There's this guy for me, that Craig Hogan,
43:39
Speaker 1: who said in two thousand and eight that he had
43:41
Speaker 1: a prediction for what he thought these gravitational wave detectors
43:45
Speaker 1: should see if we actually lived in a holographic universe,
43:48
Speaker 1: if we lived in a two D world projected into
43:52
Speaker 1: three D by our minds, then we should see this
43:55
Speaker 1: extra fuzz in these experiments from these gravitational wave detectors.
43:59
Speaker 1: So that was his diction in two thousand and eight.
44:01
Speaker 1: So we've actually seen gravitation of waves now with the
44:04
Speaker 1: Lego experiments, and so have we seen this noise? Is
44:08
Speaker 1: there evidence for a holographic universe? So that was sort
44:11
Speaker 1: of a moment of excitement because he sent his prediction.
44:14
Speaker 1: He's like, here's what you should see. You should see
44:16
Speaker 1: this kind of fuzz if you look at your data.
44:19
Speaker 1: And then they sent it back some data and it
44:21
Speaker 1: looked just like the fuzz he predicted. And so for
44:23
Speaker 1: a moment, people were like, what, hold on a second,
44:26
Speaker 1: did Hogan just proved that we live in a hologram?
44:29
Speaker 1: But then it turns out, you know, he might have
44:31
Speaker 1: seen that plot already. He might have known in advance
44:34
Speaker 1: the kind of noise that they were seeing. What it
44:37
Speaker 1: might have been a postdiction and not a prediction, right.
44:41
Speaker 1: And you know, these gravitational wave detectors are very tricky
44:44
Speaker 1: and have a lot of noise in them, and the
44:46
Speaker 1: whole game is getting them to be quiet and noise
44:49
Speaker 1: free so you can see gravitational waves. So it's not
44:51
Speaker 1: that impressive to like find noise in a gravitational wave detector.
44:55
Speaker 1: It's almost like the noise is the illusion, right, Like
44:58
Speaker 1: you can project anything you want to that noise if
45:00
Speaker 1: you do the theory right exactly. And so people did
45:03
Speaker 1: some other calculations and they realize that even if he's
45:06
Speaker 1: right that you can see it in this way, then
45:09
Speaker 1: the size of the noise he predicts is much much
45:11
Speaker 1: smaller than anything we're seeing. So so far, we don't
45:14
Speaker 1: have any evidence that we're living in a holographic universe
45:18
Speaker 1: or that the universe is a hologram. But there are
45:20
Speaker 1: clever people out there thinking about ways to sort of
45:23
Speaker 1: probe this and looking for clues around the edges of
45:26
Speaker 1: stuff to see if we're just living on a baseball card. Well,
45:29
Speaker 1: I hope it's a valuable one, not one of those
45:32
Speaker 1: common cards. It's got a baseball player slipping on a
45:35
Speaker 1: banana near a black hole. But you only think he's
45:38
Speaker 1: slipping exactly sleeping. You have to wait till the end
45:41
Speaker 1: of time to see him actually slip on the banana.
45:44
Speaker 1: All right, Well, I guess once again the answer is
45:47
Speaker 1: stay tuned. We think it's possible. Well, we know it's possible.
45:50
Speaker 1: We could be in ato the sort of universe, But
45:53
Speaker 1: I guess we don't have the instruments right now to
45:55
Speaker 1: tell the difference, or we don't know the right way
45:57
Speaker 1: to tell the difference. Even that's right, people are still
45:59
Speaker 1: thinking about and coming up with ways to predict it.
46:01
Speaker 1: And there are folks out there thinking about clever experiments
46:05
Speaker 1: that might be sensitive to the nature of space. Is
46:07
Speaker 1: it really two plus one dimensions or is it three dimensions?
46:10
Speaker 1: We don't even know. But maybe in the future somebody
46:13
Speaker 1: will unravel this. Somebody will figure out that it only
46:15
Speaker 1: makes sense for it to be two plus one or
46:17
Speaker 1: one of these listeners out there will come up with
46:19
Speaker 1: a really awesome experiment to probe the very nature of
46:22
Speaker 1: space and time. And in the meantime, I guess you
46:25
Speaker 1: should watch out for those three the snacks, because you
46:27
Speaker 1: are still three dimensions as far as everyone else. That's right.
46:30
Speaker 1: Just toss them in the black hole and watch for
46:32
Speaker 1: infinity as they very slowly fall in. It's the long
46:36
Speaker 1: term die there you go. All right, Well, we hope
46:38
Speaker 1: you enjoyed that and it didn't what flattened your mind, Daniel.
46:42
Speaker 1: I hope it doesn't change the nature of your experience
46:45
Speaker 1: in this universe, because that third dimension is pretty fun.
46:48
Speaker 1: I like being able to step over puddles rather than
46:50
Speaker 1: having to walk through them or go around them. So
46:53
Speaker 1: let's all savor and enjoy that third dimension at least
46:56
Speaker 1: while we know it's real. Well, we hope you enjoyed that.
46:58
Speaker 1: Thanks for joining us, see you, and thanks for listening,
47:08
Speaker 1: and remember that. Daniel and Jorge Explain the Universe is
47:11
Speaker 1: a production of I Heart Radio. For more podcast from
47:15
Speaker 1: my Heart Radio, visit the I Heart Radio Apple Apple Podcasts,
47:19
Speaker 1: or wherever you listen to your favorite shows.