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

Episode Date: September 16, 2021

Could the 3D entire Universe be a projection from a 2D surface somewhere? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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

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

Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Welcome to Pretty Private with Ebeney, the podcast where silence is broken and stories are set free. I'm Ebeney, and every Tuesday I'll be sharing all new anonymous stories that would challenge your perceptions and give you no. new insight on the people around you. Every Tuesday, make sure you listen to Pretty Private from the Black Effect Podcast Network. Tune in on the IHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. Why are TSA rules so confusing?

You got a hood of you. I'll take it off. I'm Manny. I'm Noah. This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that. Why are you screaming? I can't expect what to do.

Now, if the rule was the same, go off on me. I deserve it. You know, lock him up. Listen to no such thing on the Iheart radio app, Apple Podcasts, or wherever you get your podcast. No such thing. Hey, Daniel, how many dimensions do you have? Ooh, more than I'd like these days.

Too many late night snacks from the fourth dimension. Yeah, or from the fridge dimension, actually. Yeah, that's like its own mini universe of deliciousness. Where I'm both a master and the slave. But aside from how many cookies are involved, how do you know you're a three-dimensional being? I mean, I don't know. The world seems to be three dimensions. Yeah, but so does the stuff on my TV, but that's just like how your brain perceives it.

All right, well, then if I'm just like in a two-dimensional, Matrix, does that mean I can eat as many snacks as I want? Well, technically, yes, if you're in a 2D world, you can eat all the 2D snacks you want and gain zero weight. I'll be right back. Hi, I'm Jorge. I'm a cartoonist and the creator of PhD comics. I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I enjoy any dimension snack. Really? Even a one-dimensional snack? I guess spaghetti is a one-dimensional snack, technically.

Especially the spaghetti or the angel hair. Yeah, exactly. I don't discriminate. I'm not a dimensionist. I see all dimensions as equal. So welcome for our podcast, Daniel and Jorge Explain the Universe, a production of I-Hard Radio. In which we take apart the universe into its various dimensions, the ones that are understood and the ones that remain. puzzling. We take your mind on a journey into all of those dimensions, trying to understand what we do know about the universe and what we don't. We range from the smallest of questions about the smallest of things and their color and shape and whether they spin all the way out to the biggest and deepest and broadest of questions about the nature of the human context

in this crazy and beautiful cosmos. Because it is a pretty wild universe and we like to take you on the up and the down and the front and the back and the left and the right and the good and the bad jokes as well. That's right. There's a lot to explore in the universe is what I'm saying. We span the entire dimension of humor all the way from puns to dad jokes. Is there anything else? Aren't this on the same axis or the same, you know, point?

Is there such a thing as a non-silly dad pun? My teenagers say that any joke I make is a dad joke. Oh, I see. You have no death according to them. That's right. It's all one dimensional. And their sense of humor seems to be one-dimensional too, because you're pretty funny, Daniel. For a physicist, I guess.

That's a two-dimensional compliment right there. Projected onto the surface of physicists, you look pretty funny. But yeah, we like to explore all the big questions about the universe, what's real, and possibly what's not real in this universe, because this universe seems to have a lot of surprises in store for us. That's right. We as an intelligent species have been digging into the question of the nature of reality. what is actually out there and is it different from what we perceive. We would like to know something true, something universal about the universe, not just what humans

think it might be, but something we could like compare notes with aliens about. Right, but what if the aliens are, since they're in the same universe, what if they're just as fooled as we are by this crazy kind of trickster universe we live in? I believe in the wisdom of the crowd. You know, if you average over infinite intelligent races, somebody out there has got it figured out what the universe is actually like. I don't like the idea that we've all been fooled in just the same way. And you know that from the internet, I guess is a good test bet for that idea?

Yeah, absolutely. On the internet, you can find every possible opinion. With evidence, without evidence, it doesn't really matter. You can find all the dimensions there. You certainly can. But our goal on this podcast and as a species is to unravel the fundamental nature of the universe to see it for what it is and to ask the most basic questions about what it's like and its structure and its shape.

Yeah, and sometimes these questions sort of make you uncomfortable, maybe, Daniel, as a physicist, because, you know, we're sort of questioning how real is real or how real are the things that physicists think are real. That doesn't make me uncomfortable. That makes me excited. When we're on the verge of, like, revealing that the universe is totally different from the way that we thought it was, that we're all just, you know, projections on the wall of Plato's cave, that's exciting because it means we're going to learn something.

We're going to emerge from like some shroud of ignorance and actually understand something deep and true about the universe. Even if it upends everything we thought we knew and changes the entire context of our existence, that's sort of the goal of physics. Maybe I'm just projecting here, Daniel, because it makes me a little bit uncomfortable to think that everything I know is to be real

is not actually real. Well, I'm pretty sure that's true. Well, today we're going to be asking one sort of version of this question, is the universe real? And it has to do with sort of like the dimensionality of the universe and how many dimensions it actually has. And is it different than the number of dimensions we feel and see and touch and can feel ourselves in it?

That's right. And we're going to use the word dimension here. And we don't mean, you know, like the alternate dimension where everything is made out of marshmallows or where aliens escape to as sort of a parallel universe. You see that a lot in science fiction. What we mean by dimension here really is the mathematical description of it, meaning just like a direction of possible motion. And I've always found it's fascinating that our universe has three dimensions or seems to have three dimensions because you've got to wonder like, why three?

Three is such a weird number. Yeah. So today on the program, we'll be asking the question. Is the universe a hologram? Now, Daniel, are you sure we can't just talk about the marshmallow dimension where all the aliens are? That sounds like a pretty good podcast topic. Are the aliens made of marshmallows in that dimension or do they just eat marshmallows? I don't know. You tell me. You're the one projecting this image into my brain.

Maybe they go hunting for marshmallows. So the question is, is the universe a hologram? Now, this is a pretty interesting question. Are you saying like the whole universe where we live in is a hologram? Like an illusion, kind of? Yeah, that's sort of the idea that maybe the universe doesn't actually have three dimensions. Maybe it's actually just the projection in our mind. or in our experience of what's actually a two-dimensional universe

that sort of like feels like three dimensions that we can experience as if it was three dimensions, sort of like a hologram. Although, you know, it makes the universe sound like a cheap trick. Like one of those baseball cards or those little tinfoil things you put on dollar bills? Yeah, like buy yourself a 99th cent universe. Sounds like a bargain.

But I love these kinds of questions because they go to the very core of the nature of reality. You know, if we are wrong about the number of dimensions of space, what else are we wrong about? Maybe everything. And that might make some people uncomfortable, but it makes me excited because it means that there might be crazy mind-blowing revelations about the very nature of reality around the corner.

Yeah, so this is a pretty tricky question. Is the universe a hologram? And so as usual, we were curious how many people out there had thought about this question or have an opinion on this question. So Daniel went out there into the internet to, ask people, is our universe a hologram? So thank you, people of the internet, for participating. And if you are a person of the internet and you'd like to volunteer to answer random questions,

please, it's very easy and fun and just takes a few minutes. Write to us to questions at danielandhorpe.com. So think about it for a second. Do you think the universe you live in is nothing but an illusion, a hologram? Here's what people had to say. It sure doesn't seem like it. A holograph, as I understand it, is just a trick of light. I don't know what hollow means.

I'm part of the universe, and I feel like I have substance. And even if that's just a trick of my brain and I am just an image, how can a light-based image create self-awareness? So I'm guessing no. I could be somebody else's dream. Yeah, I think no. No. I don't know why it sounds like somebody gave up and said, well, it's a holograph, man. And that's it. It's a holograph. But, well, even if it's a holograph, who made it? Why? And who's paying for it? I'm not paying for that. I would say no, because a holograph is a 3D display of light, so photons, which are massless.

And as far as I can see stuff around me and me as myself, we have mass. So I find it very hard to imagine that the universe is a holograph. Of course. Of course the universe is a holograph. No, I'm not sure if the universe is a holograph or not. I have heard some theory that maybe the universe is a two-dimensional image projected onto three-dimensional space or something like that. I have heard this theory, but it's been a long time, and I don't quite remember how it goes. Well, technically a holograph, I think, is a written, something that

someone has written in their own hands. So maybe the universe is a holograph if you call God, the writer of the manuscript? Not sure of there. Maybe from our perspective on Earth, the universe actually is a holograph. For example, it bends and refracts and reflects light in many different directions depending on where you are in it.

I've heard of the holographic principle. I can't remember exactly what that is, but I think it might be related to the Maldesena conjecture which says that, Well, assuming the universe is ADS, in other words, it has negative curvature, then everything in the universe, all the information that is important in the universe can be represented on the surface of a boundary surrounding the entire universe.

All right, some pretty confident answers here. Some people were like, of course, some people were like, no, I don't think so. And so people said sounds very technical. Yeah, exactly. And I also like the ones that focus on the definition of a hologram or a holograph. Are those two things different? A holograph and a hologram? Yeah.

Confusingly, the two things have almost nothing in common. Like a hologram is what we're talking about. It's a trick of light that it gives the impression of a 3D volume from a 2D surface. You know, this is the kind of thing you'll see on a baseball car. or on a dollar bill, et cetera. A holograph is actually just like an essay written by one person in their own handwriting. What?

I know. And then holography is the study of holograms, not the study of holographs. And the holographic principle that we're going to be talking about today that the universe might be a hologram is not the hologramic principle. It's the holographic principle.

Oh, man. That's before we even get to English units, right? Because then you have to talk about the hollow pounds and the hollow ounces. And then eventually you have to talk about the hollow deck, which, you know, then we get into real nerd territory. Exactly. This entire podcast has been nothing but an exercise of the hollow deck. None of this has been real.

Your whole life. We're all just, you know, AIs and your little cosplay here, Daniel. No, I thought I was in your hollow deck experience. I thought you were the real. What? What? I thought you were, what? We were both AIs.

Somebody over here better be real. Otherwise, this whole thing is a bad joke. It's holograms all the way down. That's the real hologramic principle. So, yeah, it seems to have a lot of definitions. And so I guess let's get down to business and let's lay it down for people. Like, what is the one that we're talking about today? We're talking about holograms, right?

And I guess what does that mean? That's right. We're talking about holograms, which is part of this idea of the holographic principle that the universe might be a hologram. And so, again, what we mean by a hologram is the projection of two-dimensional surface into a three-dimensional space. And that sounds fancy and mathematical, but really what we mean is something that looks like it has volume,

like it's three dimensions, X, Y, and Z, but really there's only enough information for X and Y, that you can take all the information in a volume and somehow encode it on a flat surface. And you might be familiar with one of these things. It's something you can look at like a sheet of paper. As you change your angle, the image changes just as if you were looking at something

that had three dimensions. So we think it has three dimensions, but really it's, we're just looking at a 2D surface, which means that all of that sort of 3D information is sort of encoded or, you know, written down in that 2D piece of paper somehow? Exactly, because a 3D object, when you look at it, you only ever see a 2D slice, right? You see one side of it or you see another side of it or you see another side of it. So a 3D object has all of those 2D slices somehow encoded into it, right? And so a hologram is a 2D surface with all the 3D information encoded into it somehow so that when you look at it from different angles, you see the right 2D slice.

So your brain is like, oh, that's a 3D object. Just sort of like in Star Wars when Princess Leia is projected out of R2D2, right? It's not just she's on a screen. It looks like she's there. And they have these all over Star Wars all the time. Though they're like confusingly low tech, right? They're always like weird and flickery. Anyway, Princess Leia says, you know, help me, Obi-1, you're my only hope.

And that's a hologram because it looks like she's sort of taking up physical volume rather than just print it onto a screen. Right. And right now, you're my only hope, Daniel, because I'm a little bit confused here. Because it gets tricky, right? Because you're talking about Princess Leia. And so she's been projected into that 3D world, but we're looking at it on a flat screen. And then we're looking at it through two eyeballs, which also kind of take 2D pictures. So are we talking about the sort of illusion of depth or are we talking about things having actual depth encoded in a 2D surface? We're talking about having enough information to describe a volume but encoded on a 2D surface. So a hologram is when you can describe something using only two dimensions, but it has enough information to describe the full 3D volume.

And that's not always possible, right? It's not always possible to describe a 3D object in terms of a 2D surface. It depends on what you can do with that 2D surface. Like, how do we make holograms? How do you have those like baseball cards where it looks like the player is moving as you turn it? They do that by adding information to the 2D surface. Like they have these little ridges on the surface so that when you look at the image, you're seeing like a different part of those ridges.

And they have like different images on different parts of those ridges. So they've like done something to. to encode to add information to the 2D surface so that you have the whole 3D thing actually printed down there on 2D. Right, because they sort of like fool your eyeballs into thinking it's 3D, right? Like they give one image to one eyeball

and they give another image to the other eyeball and somehow you think it's 3D, but really it's all on a 2D surface except that on that surface, they sort of do cleverly print things so that it somehow delivers different information to each eye. Yeah, and different information to each eye. Yeah, and different information to each eye gives you the illusion of depth, but also I think it's crucial that as your head turns in relation to the 2D surface, you see a very different image.

Like if you just have a picture printed on a flat piece of paper, then as your head turns, you're seeing the same picture. You're seeing it from a different angle, but you're seeing the same actual information. In a hologram, as your head turns and you're looking at the 2D surface from a different angle, you're actually getting a different image. the image you're seeing is changing in just the same way it would if it were a 3D object and you could like look behind it or look over its shoulder or something you're revealing more information that's the experience that makes your mind think it's a 3D object now how did those work really quickly do they do they encode like the image and from every possible angle or is there something more to like you know how they use lasers and stuff like and special materials to sort of encode that 3D information there's a lot of different ways to do it none of them are perfect we can't do a complete perfect hologram yet in our universe, you know, like those baseball cards, they have a little bit of an angle there. It's obviously not a 3D object. That's done by having these little ridges so that when you look at it from a different angle, you actually see a different

image. Sort of like those billboards that change as you drive by them because it's actually like a bunch of different pictures printed at different angles. And the more clever ones, the more impressive ones use interference tricks. They send multiple beams of light from every point on the surface. And then where you are, you get a different kind of interference from those different beams. And that's what creates the sort of illusion of 3D. The dependence on your angle comes from the interference effects. All right. Pretty cool. And then I guess the question is, how could our universe be a hologram? Are you saying that we're like maybe printed on a surface somewhere with the ridges? Or do you think maybe we're, you know, what we think is the, our 3D

universe is actually printed on a surface somewhere? Or maybe there are, everything's one surface. Is that what you're saying? Yeah, that's the idea that maybe our universe can be described. The three dimensions of our universe, of space and time and gravity, can be described by information you could put onto a 2D surface. And so then that begs the question like, well, if our universe feels like it's 3D but is equivalent to a 2D universe, what's the real universe? Is the real universe two dimensions with some weird extra bits encoded onto that two dimensions, or is it actually three dimensions? Which one is like physically, fundamentally the true universe

and which one is like a mathematical equivalence? Well, I guess the question here would be, if we're actually like a 3D universe printed on a 2D surface, then like which of the dimensions is fake? Do you know what I mean? Like it's up and down fake and somehow it's encoded in the left and right, front and back, Or how would that even, like, what do you do with the expert dimension or where does it come from? Yeah, that's a great question.

Well, you know, out in the depths of space, of course, every direction is the same. You could just pick a direction and it's just as good as any other direction. So it's not like up and down or left or right or back and forth, really have any meaning in terms of the universe. So on that 2D surface, it's not like two of our space dimensions exist and the other one is just deleted. It's some other kind of space. So, like, take our three dimensions, X, Y, and Z. They map to two weird dimensions on that surface, call them, I don't know, A and B. But they're not like physical space dimensions the way we think about them.

And then there's something else going on on that surface that lets you, like, encode Z. That lets you take that third dimension and make sure that that information is not lost. But I guess if that information is there, wouldn't it basically be another dimension? Or are you saying that it's somehow encoded through some trick by the first two dimensions? No, it's basically there. And so the information is fundamentally equivalent, but it's like a different sort of structure. Like we're talking about mapping our universe, which has three dimensions and gravity and all this kind of stuff, into like an abstract space, something which is like where we talk about quantum field theory on that space.

And we talk about the relationships between points on that two dimensional surface. And so that has effectively three dimensions because it's two dimensions plus some other weird piece of information in the quantum field. There really are two different sort of visions of the universe. One is you have three dimensional space and gravity and everything moves along. And the other is that you have a two dimensional space. But then on that space is this quantum field which is capable of encoding a third dimension. All right. Sounds a bit technical.

So let's dig into the details of that. But first, let's dig a. Quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually.

impelled metal, glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In Season 2, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order.

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

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

I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Joy Harden Bradford. And in session 421 of therapy for black girls, I sit down with Dr. Afea and Billy Shaka to explore how our hair connects to our identity, mental health, and the ways we heal. Because I think hair is a complex language system, right, in terms of it can tell how old you are,

your marital status, where you're from, you're a spiritual belief. But I think with social media, there's like a hyperfixation and observation of our hair, right? that this is sometimes the first thing someone sees when we make a post or a reel is how our hair is styled. You talk about the important role hairstylists play in our community, the pressure to always look put together,

and how breaking up with perfection can actually free us. Plus, if you're someone who gets anxious about flying, don't miss session 418 with Dr. Angela Neil Barnett, where we dive into managing flight anxiety. Listen to therapy for black girls on the iHeart

radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Scott Barry Kaufman, host of the psychology podcast. Here's a clip from an upcoming conversation about exploring human potential. I was going to schools to try to teach kids these skills and I get eye rolling from teachers or I get students who would be like, it's easier to punch someone in the face. When you think about emotion regulation, like you're not going to choose an adapted strategy which is more effortful to use unless you think there's a good outcome as a result of it.

it's going to be beneficial to you because it's easy to say like go you go blank yourself right it's easy it's easy to just drink the extra beer it's easy to ignore to suppress seeing a colleague who's bothering you and just like walk the other way avoidance is easier ignoring is easier denials is easier drinking is easier yelling screaming is easy complex problem solving meditating you know takes effort listen to the psychology podcast on the iHeart radio app apple podcasts for where you get your podcasts. All right, we're wondering if the universe is all it seems to be or whether it's kind of inflated in a way,

whether it's fooling us into thinking there it has three dimensions, but really you're saying it could have two dimensions plus like a little pocket value or feel that tells you, that gives you that third extra feeling of a third dimension. Yeah. And, you know, all of this goes into trying to understand what is the nature of space itself? Like, what is this thing we call space? And I think that's really interesting and, like, historically to think about how the ancient thinkers thought about space, you know, Newton and Descartes. And those folks just thought about space as like the backdrop of the universe. It was absolute. It was fundamental. Obviously, you had to have space. And everywhere in the universe has to have space. And more recently, we've learned that space does weird things. It bends. It wiggles. It shakes. It expands. It does all these crazy things. And now we're not even sure what space is. We talked about it on a podcast episode recently, whether it's possible to even have parts of the universe that don't have space in them. You know, a universe without space. So part of this just goes to like trying to understand what is the nature of this space.

What are the rules of it? Is it really three dimensions where all those three dimensions are equivalent? Or is it actually two dimensions with one extra tricky dimension that's making us feel like it's three dimensions? And that's why these are, I think, are deep and important questions. It's like maybe we think we're in, you know, X, Y, and Z space, you know, front, back, top down, left, right. But really, we're actually in like A, B space. And each point in A, B space has a little special C value that maybe somehow those three things combined give us the feeling of X, Y, and Z. But really, it's just A and B with a little extra C. Yeah.

And that all motion, all actual physical motion only occurs along that surface, right? That A and B value. All right. So let's get into why we would think that. It sounds like a pretty crazy idea. I mean, if I think about it, I'm pretty certain we are in 3D space. You know, I can move up and down, left and right, front and back. And I can think when I touch them, they feel like they're three-dimensional. Why would we think it's not?

For a long time, we did think it was 3D space, and that felt pretty settled. Though there are ideas about how the universe might have more dimensions, you know, 11 or 26. But this particular idea that the universe might be 2D instead of having more dimensions came from the craziest thing in the universe. And so, of course, it came from studying black holes. And you know how on the extreme universe series I'm always saying, like, we look at the extremes of the universe because it shows us what's possible. It breaks the rules. It stretches them. That's exactly what happened here. People were looking at black holes and trying to understand like, what is on the inside of a black hole? What's it like in there? And some people

had this crazy idea. Maybe it's not like anything. Maybe there is no inside door. black hole. Maybe all there is to the black hole is the event horizon. Maybe black holes are actually just two dimensions. Yeah, we've had episodes about what happens when you go inside of a black hole and what they are. And I think it is that like when something sort of goes towards a black hole because of the way it bends space and time, it never actually goes in, right? Like it basically stops at the surface forever in a way. It depends on who you ask, which is the tricky bit. So if you are watching something fall into a black hole, then as it gets closer and closer to the black hole, space is curved more and more. And then there's more and more gravitational

time dilation, which is an effect where time slows down where space is curved. And so the closer you get to the black hole, the more time slows down. And so you never actually reach it. You have to wait for time equals infinity to see something actually fall into a black hole. That's if you're the person on the outside watching, right? If you're the person jumping into the black hole, then you don't experience any of that. And just like in relativity, your experience of time depends on who you are, where you are, and how fast you're going. And so in this case, you just fall right in. You pass through the event horizon. You head towards the singularity. And so people are wondering like, what's going on? How can everything be smeared on the outside

of the black hole and also be inside the black hole? How is that possible? You're saying it depends on who you ask, right? Like to us on the outside, and far from a black hole, hopefully, things get mirrored on the surface of the black hole, the event horizon, but you're saying to the person falling in, they just fall right in, but at time infinity for us. Yeah, that's exactly right. We see them fall in only at time equals infinity, but they see themselves fall in, you know, very normally and very naturally. And these two things contradict each other. And so often in relativity, you have people having different accounts of the same situation and both being correct. And that's possible in scenarios where there's like no causal

link between the events. They have a time like relationship, for example. But here it's hard to understand, you know, how the black hole actually accumulates stuff, whether there actually are things inside the black hole. And it goes to this question of like the black hole information, right? We talked about how if you put something into a black hole, then its information is inside the black hole. Like you throw a banana in there. Where does its energy go? Where does its entropy go? Where does its quantum information go? And people are trying to understand like what happens when these black holes evaporate. Is everything actually on the surface of the black hole? And so it never really fell in. And so its information wasn't lost or was it inside the black hole actually? And when the black hole

evaporates, its information is somehow lost. So it's important whether it's actually gone inside the black hole or not. And then can you still slip on the banana there? If it's on the surface of the black hole? That's really the important question. I mean, that's what this whole thing has been building to know. Well, I mean, if you're going to do a cartoon on the surface of a black hole, you want to make it physically accurate, right? And every cartoon is got to have somebody slipping on a banana. And so I appreciate your desire here to do physically accurate black hole surface cartoons. Thank you. Comedy, yeah. And then you laugh about it at the end of time. No, but I think what you're saying is that there's this kind of paradox, right? Like we think things splat on the surface,

But according to the people going in, they go inside. And so there's this kind of idea that maybe, you know, once you go inside, you're just like on a 2D surface of the black hole. Yeah, that was sort of the start of the puzzle. Like how do you reconcile these two things? They seem like fundamentally very different things. And Hawking and this other guy, Beckinstein, we're working on this and trying to understand like,

where is the information in a black hole? How does it actually work? And they were working on this one day. And they were calculating how much information can be encoded inside a black hole. They were working on these calculations of black hole entropy thinking about black holes as like thermodynamic objects with temperatures that radiate and all this stuff. And one day they arrived at this equation and this equation told them that the amount of information inside a black hole doesn't depend on the volume of the black hole. It depends on the area of the

surface of the black hole. So like it doesn't depend on the radius cubed. It depends on the radius squared. And that's kind of interesting. That's a suggestion. It says, like, hmm, the maximum information you can store in a black hole depends on the area of its surface, not on its volume. That suggests that maybe actually these are just two-dimensional objects. Like a black hole is just a two-dimensional object, but we see it grow, right? Don't we see it grow? Doesn't that mean that it has volume to it?

It could be a two-dimensional object embedded in our 3D world, right? Like the surface of a sphere technically is a 2D object. It's embedded in a three-dimensional universe. it has a radius, it can move around in three dimensions, but it's actually a 2D object, like an infinitely thin sheet of paper, would also be a 2D object. So that's where this idea of a holographic universe,

hologramic, holographic principle of a holographic universe, meaning the universe is a hologram. So you're saying that a black hole could be a two-dimensional object in our 3D world. So how do we go from there to the whole universe is just 2D? Oh, we didn't yet. First, we're trying to understand the interior of a black hole, and the first step was to think, well, maybe the interior of the black hole is a hologram, right?

Maybe there is no interior. So if you are that person that fell into the black hole and you think you're on the inside of the black hole, you're actually not. You're actually still on the surface. But the whole surface of the black hole has enough information to encode what feels like a 3D internal volume. So first, before we go to the whole universe, people thought maybe the 2D surface of a black hole is a hologo. that projects the 3D interior. So then what happens as the black hole grows? The whole inside stays on the surface, but it grows with the black hole?

Oh man, you can't think about that. You can't change the parameters. This only works for a single thing falling into a black hole. It gets much more complicated as soon as you add like something else to a black hole. You know, for example, if you throw a banana into a black hole, then in principle it never actually enters the event horizon. It's smeared across the surface forever, right? and that's what we're talking about.

Now, if somebody behind you throws in an apple, everything changes because that apple will now change the shape of the event horizon. The event horizon will actually grow out to meet that apple as the apple falls in and it will absorb the banana. So it's a totally different scenario if you're now like tossing in multiple things into the black hole. Not even something we're capable of thinking about carefully. But that is what's happening right now in the universe, right? Like black holes are constantly sucking stuff in, things are constantly falling into.

and they're constantly growing. So why would we think that that's what's going on then? Yes, that is definitely what's happening in the universe. And we see black holes actually growing. And so we don't know what's going on there. If you're the banana and you're like smeared across the black hole surface and then somebody else throws in an apple and increases the size of the event horizon, it increases the surface area.

And now that surface area in theory should be capable of describing a larger internal volume. There is nothing actually inside the black hole. this picture. Inside the black hole, there's no space. There's nothing. There isn't anything in there that's not 3D space that you can move around in. There's just this weird surface that has mathematically encoded onto it enough information to describe a 3D space. So the banana and the apple feel like they're in a normal 3D space inside the black hole, but they're still smeared across the edge of it. All right. So then thinking about black holes and what happens at the surface is what sort of led us to this idea of a universe as a hologram. Like,

Are you saying that we're a universe imprinted on the surface of a black hole? Or are you saying that just thinking about black holes let us to think, like, oh, maybe the whole thing is imprinted somewhere else? Yes, exactly. This idea from black holes led us to think more carefully about the relationships between 3D spaces and 2D spaces. And there was a bunch of guys working on string theory. And string theory is really, really difficult.

It's really hard to do any sort of calculation in string theory. And sometimes when a problem is too difficult, you look for like a mathematical trick to make it easier. There's this idea that you could have a three-dimensional universe encoded on a two-dimensional space, and some folks realize that if you did that with string theory, it might solve some mathematical problems. Like if it's too difficult to do a calculation in two dimensions, well, what if it's actually a three-dimensional universe and you can do the calculation there? And so people were playing around with that and realizing, oh, you can play the same game, not just with a black hole, but with string theory. And so maybe you can describe

the entire three-dimensional universe that has strings in it as a two-dimensional service. And that would make some calculations easier to do and other calculations actually harder to do. But they sort of projected this whole idea onto the universe. And that's a really fun moment in science when you're like build a tool over here and you're like, oh, this is cool, this solves this problem. And then you turn around, you're like, hold on a second. Maybe I could do this to everything, you know. Maybe I can make it two-thirds easier.

I don't have to do as much math. Yeah. And so there was this really big, important result by a guy at the Institute for Advanced Studies in Princeton, where that collection of smart folks over there called ADS-CFT, which you can Google if you're interested in more details about it, or maybe we'll do a podcast episode about that. But it gave us this vision that maybe the entire universe can be described in terms of being a 3D illusion of a two-dimensional surface somewhere.

All right. Well, I have two questions for this three-dimensional problem. I guess the first one is, where did the third dimension go? Like, how is it being encoded in this to the surface? And two, could we ever tell the difference whether or not we are in a hologram or not? So let's get into these questions. But first, let's take another quick break.

LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently the explosion actually impelled metal glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene. In its wake, a new kind of edict. emerged. And it was here to stay. Terrorism. Law and order criminal justice system is back.

In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot.

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

I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Joy Harden Bradford, and in session 421 of Therapy for Black Girls, I sit down with Dr. Othia and Billy Shaka to explore how our hair connects to our identity

mental health, and the ways we heal. Because I think hair is a complex language system, right? In terms of it can tell how old you are, your marital status, where you're from, you're a spiritual belief. But I think with social media, there's like a hyper fixation and observation of our hair, right? That this is sometimes the first thing someone sees when we make a post or a reel is how our hair is styled. We talk about the important role hairstylists play in our community. the pressure to always look put together and how breaking up with perfection can actually free us. Plus, if you're someone who gets anxious about flying, don't miss session 418 with Dr. Angela Neil Barnett,

where we dive into managing flight anxiety. Listen to Therapy for Black Girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about exploring human, potential. I was going to schools to try to teach kids these skills and I get eye rolling from teachers or I get students who would be like it's easier to punch someone in the face. When you think about emotion regulation, like you're not going to choose an adaptive strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial

to you because it's easy to say like go you go blank yourself right? It's easy. It's easy to just drink the extra beer. It's easy to ignore to suppress seeing a colleague. who's bothering you and just like walk the other way. Avoidance is easier. Ignoring is easier. Denials is easier. Drinking is easier. Yelling, screaming is easy.

Complex problem solving. Meditating. You know, takes effort. Listen to the psychology podcast on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel, here's my favorite question in these episodes. What does it all mean, man? Like, if we're actually, if our 3D universe is actually imprinted on a 2D surface somewhere,

like where did the third dimension go? Is it just an illusion? Is it actually there? You mentioned like maybe it's encoded in some quantum fields. Can you talk more about that? Like, how does that encode a whole dimension? Yeah, so think about space, right? You think about space is emptiness.

But we actually know that space isn't just empty, that everywhere in the universe, space has these things in it we call quantum fields. And what is a quantum field? Well, it's just like a number at every point in space. So, for example, you know, there's the electromagnetic field. And anywhere you go in the universe, you can ask, what's the strength of the electromagnetic field here? What's the strength of it over there? It's something that has like a value at every point in space.

And the EM field is actually more complicated because it has more than just a value. It has like multiple values for every point in space. but that doesn't matter. So this is something which is sort of like added to space. You know, it's like if instead of just having a city with an address where you have a house at every location, now inside that house you have a number,

like how much is that house worth, right? So that's like another piece of information at every point in space. It's encoded into this quantum field. But there's lots of quantum fields, though. You're saying this like extra information is encoded in all the fields or like there's one quantum field for basically the Z direction? Yes, there's a special quantum field because if you just have a quantum field,

it can have like arbitrary random values and that doesn't give you like a dimension. Instead, if you have a special quantum field that follows certain rules, these are called conformal field theories. If you have a quantum field which looks the same if you zoom in really, really close or if you zoom out really, really far, if it tends to follow the same rules, but things that are zoomed in really, really close don't interact very well with things that are zoomed out really, really far, then the mathematical structure of that quantum field theory has some

symmetries to it, which allow things to behave exactly as if there was a third dimension. Like if things that are zoomed in really, really small, don't interact with things that are like really zoomed out in this quantum field theory, then it's sort of like things passing by each other in that other dimension. And, you know, if there's a scale that you can like zoom, zoom in and zoom out, then it's sort of like there's another direction there in this quantum field. And so this is like a way to encode something into the quantum field by adding a bunch of rules for how it behaves. And those rules essentially make it as if it was exactly like a dimension. I kind of feel like maybe you're trying to pull a fast one on here, here, Daniel.

I am 100%. I feel like you're trying to paint an illusion here. I feel like maybe you're saying that there maybe are three dimensions, but one of them, you don't want to call it a dimension. You know what I mean? Like maybe it feels like maybe it's just like a technicality about the naming of it. But if it acts and looks like a dimension, why not just call it a dimension?

I got nothing against calling it a dimension, but it is different from the other two, right? And our program here, not just on this podcast, but as humans trying to scratch out the nature of the universe, is to figure out the nature of the universe. And so if it turns out that two of the dimensions are different from the third dimension,

then that's quite interesting. And so we'd be fascinated to discover, for example, that our universe was actually one dimensions with like two weird projected dimensions instead of being three dimensions. Or if we were like, you know, a three dimensional surface in a four dimensional space. I think I would definitely want to know that. You know, it doesn't change how you live your life necessarily or whether you should buy insurance. Yes, definitely buy insurance. But it changes, I think, our concept of the nature of reality. So I definitely want to know, even if mathematics.

the two things are totally equivalent. Physically, it means that one of these dimensions is not the same as the other two. Right, but is it not the same in that fundamental of a way or is it just different in a sort of like notation mathematically way? No, I think it's fundamentally different because that would mean that space itself is two dimensions. And remember, one of our goals here is to understand the nature of space.

And so space itself is two dimensions, but then it has these properties, you know, these properties which allow to do things that three-dimensional space would do, then that's different from living in three-dimensional space, yeah. I feel like you're trying to pull Pluto here on the up-and-down dimension or something. It's technically a dimensionoid, not a dimension. It's a dwarf dimension. Yeah, exactly.

But, you know, some of these calculations, these string theory calculations are harder to do in a certain number of dimensions, and they make more sense in fewer or in more dimensions. And so if the sort of fundamental theory of everything turns out to only work in two dimensions and not in three, that also sort of tells you something about the nature of the universe itself. You know, the universe pervers the two-dimensional description. I mean, in theory, you could describe the universe in terms of any number of dimensions you want, but we're looking for the most compact, the simplest, the most natural description that we hope reveals not just the way we are thinking about things, but the actual structure of the physical universe outside our minds.

And I guess it also sort of depends on what you define a space, right? Like space, if you define space as only the two dimensions you like, then yeah, it's only a two-d space. But if you maybe define spaces these two dimensions plus this extra, you know, valley of the quantum field, then, you know, maybe that is what space is, quote unquote. That's definitely what our experience of space is, right? Either space is naturally three-dimensional or it's two dimensions with this extra wiggle room in it that allows us to experience it as. if it was three dimensions. I mean, it sounds to me like your question is sort of like saying, isn't a hologram actually a 3D object?

Like, well, no, it's not really there. You know, like it really is just a 2D surface. Baseball card isn't actually three dimensions. And you might say, well, it doesn't look any different. If you couldn't actually tell, what would it matter? Well, it matters to me because I want to know the truth, man. What does it all mean? All right.

Well, let's get into the last question here, which is how would we even tell if we are in a 2D or 3D universe, right? Like if the difference is so small or subtle or kind of sort of like, you know, complex, will we ever be able to, you know, devise an experiment to tell us whether we are 2D or 3D? Well, we're not sure, but there are some folks out there who have some really fun ideas for figuring out if we actually live on a 2D surface. And the idea is that a 2D surface with a projection and a 3D surface would actually be different because there would be different quantum fluctuations.

Like we are talking about a quantum field generating this third dimension, right? And so we would definitely be sensitive to like the way these fields fluctuate. And quantum fields fluctuate differently in two dimensions and in three dimensions. We had a whole fun podcast episode about the nature of 2D objects. You should go check that out. But things move differently in two dimensions and in three dimensions. And so they fluctuate differently. And so we can see like quantum fluctuations from the very, very beginning of the universe.

Quantum fluctuations you normally think of like, oh, this electron went left instead of right and nobody really cares and nobody can ever see them. But in the very beginning of the universe, those fluctuations dictated like how things happened and they got blown up into real measurable effects. So if there was a 2D world, we would see different quantum fluctuations than in a 3D world and we might be able to see hints of that in remnants of the early universe. universe. Oh, I see. Because when the universe was born, you're saying at the Big Bang, you know, things were so compact and hot and small and dense that quantum fluctuations were a big deal. And so as the universe blew up, if there was actually only two dimensions, then we would see something funny going on right now in sort of the universe around this. And because this bonus dimension is responsible for making the third dimension and affecting how gravity works in this three-dimensional world, we should be able to see it in gravitational wave detector. Basically, the bottom line is that if we live in a two-dimensional world with a funny bonus dimension, we should be able to see a weird sort of like noise in gravitational wave detectors that you wouldn't otherwise see. This noise would be like an extra fuzz or a unique kind of fuzz that comes from the 2D surface

instead of being in a 3D world. But I think you're saying, you're not saying that there's like one dimension that's fake. You're saying that, you know what I mean? Like it's not like Z is fake. it's more like X, Y, and Z actually map to A, B, and a little bit, and something bonus calls C. You wouldn't see black gravitational waves, for example. You would see some weird mathematical or some weird dependency on the gravitational waves. Yeah, exactly.

The idea is if all the three dimensions are not the same, if two of them are actual dimensions and one of them is just a bonus, then there are different rules for those dimensions. And when it comes to things like quantum mechanics, and so they have different impacts on things like gravitational waves, and we should be able to see if there's like two dimensions of noise in the gravitational waves or three dimensions of quantum noise in the gravitational waves. That was the idea, at least. There's this guy from a lab Craig Hogan, who said in 2008 that he had a prediction for what he thought these gravitational wave detectors should see if we actually lived in a holographic universe.

If we lived in a 2D world projected into 3D by our minds, then we should see this extra fuzz in these experiments from these gravitational wave detectors. So that was his prediction in 2008. So we've actually seen gravitational waves now with the LIGO experiments. And so have we seen this noise? Is there evidence for a holographic universe? So there was sort of a moment of excitement because he sent his prediction. He's like, here's what you should see.

You should see this kind of fuzz if you look at your data. And then they sent back some data. And it looked just like the fuzz he predicted. And so for a moment, people were like, Hold on a second. Did Hogan just prove that we live in a hologram? But then it turns out that, you know, he might have seen that plot already. He might have known in advance the kind of noise that they were seeing.

What? It might have been a postdiction and not a prediction, right? And, you know, these gravitational wave detectors are very tricky and have a lot of noise in them. And the whole game is getting them to be quiet and noise-free. So you can see gravitational waves. So it's not that impressive to like find noise in a gravitational wave. detector. It's almost like the noise is the illusion, right? Like you can project anything you want into that noise if you do the theory right. Exactly. And so people did some other calculations

and they realize that, oh, even if he's right that you can see it in this way, then the size of the noise he predicts is much, much smaller than anything we're seeing. So so far we don't have any evidence that we're living in a holographic universe or that the universe is a hologram. But there are clever people out there thinking about ways to sort of probe this and looking for clues around the edges of stuff to see if we're just living on a baseball card. Well, I hope it's a valuable one, not one of those common cards.

It's got a baseball player slipping on a banana near a black hole. But you only think he's slipping. He's actually sleeping. You have to wait to the end of time to see him actually slip on the banana. All right. Well, I guess once again, the answer is stay tuned.

We think it's possible. Well, we know it's possible. We could be in a 2D sort of universe, but I guess we don't have to instruments right now to tell the difference or we don't know the right way to tell the difference even that's right people are still thinking about it and coming up with ways to predict it and there are folks out there thinking about clever experiments that might be sensitive to the nature of space is it really two plus one dimensions or is it three dimensions we don't even know but maybe in the future

somebody will unravel this somebody will figure out that it only makes sense for it to be two plus one or one of these listeners out there will come up with a really awesome experiment to probe the very nature of space and time and in the meantime I guess you should watch out for those 3D snacks because you are still three dimension as far as everyone knows. That's right. Just toss them in the black hole and watch for infinity as they very slowly fall in. It's the long-term diet. There you go. All right. Well, we hope you enjoyed that. And it didn't, what, flattened your mind, Daniel? I hope it doesn't change the nature of your experience in this universe because that third dimension is pretty fun. I like being able to step over puddles rather than having to walk through them or go around them.

So let's all savor and enjoy that third dimension, at least while we know it's real. Well, we hope you enjoyed that. Thanks for joining us. See you next time. Ah, come on, why is this taking so long? This thing is ancient. Still using yesterday's tech, upgrade to the ThinkPad X1 Carbon, ultra-light, ultra-powerful, and built for serious productivity. With Intel core ultra-processors, blazing speed, and AI-powered performance, it keeps up with your business, not the other way around.

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

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

Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. This is an IHeart podcast. Thank you.