Daniel and Kelly’s Extraordinary Universe - Could there be two dimensions of time?

Episode Date: August 23, 2022

Daniel and Jorge grapple with the possibility that time could flow in more than one direction, at the same time(s).  See omnystudio.com/listener for privacy information.

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What? How's that possible? I don't know. You're the physicists. You tell me. Something about relativity, maybe? I can't use relativity to understand cartoonists and their slippery relationship with time. Well, there's no time like the present. This is going to take some time. Hi, I'm Jorge. I'm a cartoonist and the co-author of Frequently Asked Questions about the universe. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I seem to never have enough time. Really? I guess professors are pretty busy. Or do you just live in a different space time there in your physics department? Yeah, I try to travel at very high velocities. so I can take advantage of time dilation when I'm answering my emails.

Oh, I see. But you try to write them as fast as possible? Is that how it goes? Like all academics, I'm trying to get as much done in as little time as possible. But you're also quite busy with all of your projects. I am. Yeah, I keep pretty busy. But, you know, as they say, we don't have the time.

You got to make the time. Physicists can make time, right? That's a magic power you guys have. We don't even understand what time is, man. Not to mention how to make more of it. Well, it's time to tell people, welcome to our podcast. Daniel and Jorge Explain the Universe, a production of IHeart Radio. In which we take the time to delve into the deepest mysteries of the universe.

How it works, how it flows, what its fundamental nature is. What are the basic building blocks of this crazy insane universe that we live in and so thoroughly enjoy? Including deep questions like, what is the nature of space itself? How does time flow? Is time part of space? Is space part of time? Is it altogether a big part of space? What the heck is going on anyway?

That's right because there's no time like the present to study and think about time itself and the present and the future and the past of this crazy and amazing universe that seems to somehow sometimes defy our understanding. I think a lot of people imagine that physicists who are trying to understand the universe are working on like really deep, difficult questions. Questions you wouldn't even understand if you heard somebody say it out loud. But the opposite is true. physicists who are working on the nature of the universe are still asking the same questions that people have been asking basically since people have been asking questions what is space anyway how does time work because we've made almost zero progress understanding these basic things about the universe I thought you were going to say that the opposite is true that physicists don't actually work I thought that was where you were going you know like most things that abut philosophy it's all about your definition of work I thought you That stuff is it had a very clear definition of what work is. Yeah, exactly. If I'm lying on my couch and I'm not moving in relation to any of the forces,

am I technically not doing any work? I don't know, but I'm getting paid anyway. So technically the IRS calls it work. So, hmm, already we're in a tangle. Yeah, it's called special IRS relativity. I think you can go to jail for that. For a relatively long time, too. Yeah.

And you can do time in jail also. What do you think about time? But it is an amazing university. And sometimes it's kind of hard to comprehend. I mean, we sort of think we know what's going on. We have some sort of intuition that we have grown up with or have heard about through physics classes and things like that. But as we learn more about the universe, the more it presents challenges for our ability to understand it.

And the funnest questions are the most basic ones, the ones that try to dig into the very firmament of our understanding, that like push on the boundaries of the possible, you know, that ask, what if the universe was slightly different? What if this basic thing we think is always true about the universe wasn't actually true or was different or was different here than it is in Alpha Centauri? When I was a kid struggling to wrap my mind around the questions of the universe, this was one of my favorite ones to think about. What if space and time were different in some way? What if the way we move through space, the very feeling and nature of space itself was not the way that we thought it was, was somehow fundamentally different? Yeah, and we are all about asking crazy fundamental questions. today on the podcast, we'll be asking,

are there two dimensions of time? And Daniel, here you don't mean like cartoonist time and physicist's time, right? You mean like actual dimensions of time. Yeah, cartoonist time can't actually be brought into a single mathematical framework because one is imaginary, so it's impossible. Is that the Heisenberg, cartoonist, physicist, uncertainty principle? Exactly. That's the, do cartoonists actually read their email uncertainty principle?

which we have pressed to as limits on this project. But this is a really fun question. And before we dig into it, I'll note that we actually got to the question of the episode before the 10-minute mark, which is something of a record for us. Speaking of time. Oh, hey, maybe we're moving in a whole new time dimension right now.

I wonder if people are confused. They're like, what? They're actually getting to the point. Exactly. I think there might be folks out there to just skip the first 10 minutes of the podcast. It's mostly us talking about chocolate and bananas. I have seen those complaints on the Apple reviews. But you know, some people love that bit and some people don't.

So, hey, skip if you like, don't skip if you don't. Yeah, there you go. You can't go back in time on a podcast player. So, but you can't go forwards in time. So feel free to skip forward if you're not enjoying this. Anyway, while we celebrate getting to the topic of the podcast without spending too much time at chit chat, we're chit chatting away all that precious time. Yeah, let's get to it here.

Daniel, this is an interesting question. So are there two dimensions of time? I'm like, I wouldn't even have thought to ask this question before an hour ago. Well, that's what's so fun about it, because even the related question, are there other dimensions of space, is one that's hard to grapple with, this idea that space has three dimensions and what if there are more, right? But now we know there are connections between space and time, and people sometimes think about time itself as a dimension. So if there can be multiple dimensions of space, more than three, up to 26, why not time? And these questions in physics or philosophy of physics sometimes just start with that. why can't things be this other way?

Yeah, it seems nonsense to you immediately, but maybe that's just because of the way you've been thinking about the universe. The universe itself doesn't have to obey your restrictions. Right. I feel like that's a big part of being a physicist is sitting around thinking, what if there are more? We need more, bigger, faster, more of them. We definitely do.

And that's one of my favorite parts of physics, not just actively sitting around and wondering if the universe could be different, but looking back through the history of physics and finding those moments, those incredible realizations when we discover that the universe actually is quite different from the way we had always assumed it to be. From understanding that the universe might be billions of years old instead of thousands, to understanding that the universe could be infinite, to understanding how space and time flow, to figuring out that quantum mechanics rules the microscopic universe. There are all these moments when somebody has finally understood the universe is not the way that we expected it was. And the way to make those discoveries is to keep asking those kinds of questions. Yeah, the universe has surprises many times in the past and hopefully also in the future.

And especially with this interesting question about whether there are more dimensions of time. Because I think most people just assume there's just one time, right? A lot of people ignore time. There's time zones. But yeah, we mostly imagine that time flows and that it only flows in one direction, right? And that it can only flow either forwards or backwards because we think of time. having just a single dimension to it, right? Forward and backwards, not some like strange plane of time

or cube of time or something even crazier. Yeah, although I do give my kids a lot of timeout. And I think they feel like they're in a separate dimension when they have to wait for it to run out. Step into the cryo chamber, kids. Is that a Star Wars reference there to Hans Solo? Carbonite. Do you think I carbonite my kids? I don't know how you make your choices, man.

I'm not judging anybody's parenting. When you say time out, it could mean a lot of things. Oh, boy, yes, I could stick him in the room with, like, candy and video games. That would be a parenting choice, yes. I don't want to alienate any of our listeners. But it is an interesting question. And as usual, we were wondering how many people out there had taken the time to think about time in this way and to wonder if there's more than one dimension of time. So thank you very much to everybody who volunteers to answer these weird and wonderful questions about the universe.

They give us a sense for what people are thinking and what people already know. We'd love to have you participate for future episodes, so please write to us to questions at danielandhorpe.com. Everybody's welcome. So think about it for some time. Do you think there is more than one time dimension? Here's what people had to say. There could be more dimensions, more time dimensions than one.

Most likely it can be more than two. But since we can only perceive one, maybe this one that we perceive it, has, for instance, the past, the future, and the present. Maybe you can see, you can split it in three dimensions. I'm not certain of how a second time dimension would work. I'm going to go with maybe, but I can't think of a good way to structure that right now. I believe time is one-dimensional because as per our current understanding,

It's theoretically possible to travel forward in time if you travel near the speed of light related to something. But I don't see any theories that suggest that it's possible to travel backwards in time. So we can only go forward. So yeah, that's what I think. It's one dimension. So I guess forward and back would be one dimension. So two dimensions is like a sheet of paper. that is very hard to think about.

I'm just going to go if no. It doesn't make any sense to me. Oh, I think so. I think that would be really cool, and I don't know what it would mean, though. I would say there couldn't be a second dimension of time unless there's the multi-universe theory and that there's your x-axis, which is timing forward,

but then there's also this y-axis of many different times moving forward. But if that's not the case, I'd say no. There's only one dimension of time. All right. some interesting answers here. How much time do you think people spent thinking about this answer? I don't know, but I think it increased the fraction of their lives where their minds were blown. Which I'm sure it was timely and right on time. Well, that's really the goal of this podcast is just to share the joy of having your mind blown,

of thinking about the universe in a new way. So I love hearing in real time these folks grappling with this crazy and difficult question out. And I totally admit I have trouble with also. Well, a lot of people here seem to think that there couldn't be more than one time dimension. I mean, we were sort of used to the past and the present and that's it. But I like this answer here that says that maybe in a multiverse, there is more than one time, right? Like each universe would have its own time if there is a multiverse. Yeah, in the sense that each universe would have its own space and its own time. I think this question is more about whether our particular universe, our space time, has more than one time dimension.

You know, if there are other universes out there that have their own space, that doesn't like give you. a new way to move left, right, up, down, forward, backwards. So that seemed to me like a bit of a Marvel loophole. Which, as we know, are terrible ideas because they don't make any money at all. But it is a sort of a loophole that you didn't quite specify in your question, though. So technically they could be right. Yeah, push the boundaries, people. Exactly.

Think creatively. It was Kevin Feige, the producer at Marvel, who phoned in with that answer. Kevin, give us a call. we'd love to have you on the podcast. But it is interesting to think that maybe there is not just the one time that we have here in our universe. There could be maybe more time dimensions. And so, Daniel, let's step through this for people. And let's start with the basics.

What exactly is a dimension? Right. A dimension is one of the most misused words in science fiction. You see it all the time, people traveling to another dimension. And when they say dimension in science fiction, really they mean some other universe, some complete other existence, maybe with different rules of physics, different space, maybe different time, whatever, different crazy beings covered in marshmallows, who knows what. It's sort of just like somewhere else.

But that's not the physics definition of a dimension. That's a science fiction definition of a dimension. Right. And sci-fi movies and TV shows, they always like open a door into another dimension and you step through it and it's like you're in a different version of your universe, but it's like slightly different, like the upside down and Stranger Things. Yeah, Stranger Things is a great example. of another location.

And they don't actually call it a dimension in Stranger Things, which I like. But that's sort of like the concept people have in their mind of another dimension. But when physicists talk about a dimension, they just mean a direction that you can move in. So our space has three dimensions to it. If you draw a straight line through space,

you can move along that line. Maybe that line is like forwards and backward. Now draw another line that's perpendicular to that line. That's another direction you can move in. And because you've made them perpendicular, motion in one is independent from motion in the other. Like if you now have two lines, X and Y, then you can completely describe

the location anywhere on a two-dimensional plane. And no motion in X can change your motion in Y. So you really need two dimensions to describe a plane. And then there's a third dimension you can add, which is perpendicular to both X and Y, call it Z, for example, maybe it's up and down. So we have three dimensions of space that we're aware of, and you can't add a fourth.

There's no way to add enough. another line that has a 90 degree angle to x and y and z there isn't like room for it in our space that we're aware of well there's no room for it in three-dimensional space for a fourth dimension by definition right but that doesn't mean it's not mathematically possible it is mathematically possible to create four-dimensional spaces so we're talking about our physical universe our space feels like it has 3d in it because it feels like it's well described mathematically in three dimensions but you're right you could potentially have a 4D space and mathematicians have no limit to the number of dimensions they can imagine. It's hard to sort of grapple with

and have a visual of it. But in a four-dimensional space, there is another dimension, which is perpendicular to all the other three, meaning that there's some way you can move, some direction you can slide in that isn't described by the previous three dimensions. There's like version of this three-dimensional space and then you move along that fourth dimension. There's another version of that three-dimensional space. So space really has like another digit to it. Right. So that's three-dimensional space. And I think we're all, you know, pretty familiar with it, having grown up with it all our lives, where you can, you know, move forward and backwards and up and down and left and right, and they're all sort of independent.

But then there's also the idea that maybe time is a dimension, right? And in fact, that maybe time is like a brother or a sister to the space dimensions. Yeah, it's a really fun idea and it's really sort of mathematically beautiful. But it's not something that physicists really understand. And it goes to the heart of one of the biggest conflicts and open problems in modern physics, which is, who's correct, quantum mechanics or relativity? Because these two theories, which are like the pillars of physics, have different views about what time is and whether it's a dimension in the way that space is.

So let's start with relativity, because relativity is the idea that connects space and time really intimately. It says, like, you know, space by itself and time by itself don't really make sense to think about independently. Make more sense if you bundle them together into some four-dimensional object, call space time. So you take the three dimensions of space and you add time to it. You have this now mathematically four-dimensional construct, which you can treat as if it was a four-dimensional space time. Right. That happens in the math where you just kind of like add another, you know, space in your vectors to, to think about time. But in a sort of an interesting way, it sort of kind of means that time is sort of another way that we can move or another thing or another

direction that we can move through and that's kind of true right like we're moving boards and time as if we were moving along a direction there we are moving along a time axis and that's why mathematically it's sort of possible to combine these things i think it's also worth spending a moment thinking about like why you would do that how do you justify that because in principle you could combine anything you know you could add apples to space and say oh i have now an apple dimension or something counts the number of apples in the universe like that doesn't necessarily make sense or give you you any extra explanatory power about the universe. But adding space and time together really does. It's one of these examples where we see two separate things, neither of which makes sense

completely on their own. But when you both them together, you suddenly get a crisper view, a simpler understanding. You know, it's like seeing two sides of a coin and thinking they're totally separate and then understanding, oh, these are two sides of the same thing. Or how we knew about electricity and magnetism. And there were things that didn't really quite make sense until we put them together and say, actually, this is just one thing, and we have a simpler set of equations that describe electromagnetism instead of trying to think about these things separately. In the same way, when Einstein put space and time together, a lot of things got much simpler in terms of the mathematics. A lot of symmetries are obeyed by space time that are not obeyed

by space or by time separately. So that's the thing that makes relativists, people who believe relativity is the foundational explanation of the universe, convinced that space. Space time is a more natural way to think about space or time. Right. It's like including time as the dimension in the equations makes the equations kind of click, right? Like it makes them make sense because there are some transformations, I guess, in the math. And when you were trying to do physics that just makes sense if you also include time as a dimension. Yeah, we know from relativity that time is not universal.

You know, that depending on who's looking at the clock and their velocity relative to it, it flows differently. And the same is true of space that people who try to measure distances and, lengths. It depends weirdly on who you are, where you are, and how fast you are going. But if you combine these things, space and time together, then you get a lot of invariance, things that everybody can agree on. If you just talk about where you are in space, time, rather than just talking about where you are in space, we're just talking about where you are in time. And you're right. Fundamentally, time can be viewed as a dimension there because you are moving through it. You have a coordinate. Now is a coordinate in time. Now plus 10 seconds

is a coordinate further along that axis. So if you like to think about dimensions, it's like these glowing arrows through space telling you where you are like grid lines on a map, you can also do the same thing for time and think about it as a coordinate of that time dimension. Right. And time, I think we sometimes use it as a good way to sort of illustrate what it would be like to move

in higher dimensional space. Like if maybe space had four dimensions, like time is what that extra dimension might feel like, right? Like I'm here sitting on my desk in one point in three dimensional space, But at the same time, I'm sort of moving without thinking about it, moving through another dimension that's independent of those three dimensions, but it's like I'm moving through time, which means I'm moving through that dimension. Yeah, absolutely. You know, if you think about like somebody on a 2D surface, imagine somebody living on a piece of paper, you pass an orange through that piece of paper, it's a 3D object. They only see a 2D slice of it.

What do they see? They see a dot appear. Then that dot grows into a circle and then it shrinks back into a dot. So they're seeing a 2D circle that's changing in time, as you say. You're passing a 3D object through the plane. Now, in our world, if somebody passed a four-dimensional orange through your kitchen, what would you see? You would see a 3D orange dot appear and grow until its maximum value

and then shrink back down to do a dot and disappear. So do things that like normal 3D objects can't do. So there we're using fourth dimension of space as an example. But as you say, also sliding through time can give you that same kind of experience. The whole 3D space can change with time. Right. It's almost like if you're sitting there and not moving, you're not moving in three-dimensional space, but your clock, your watch is telling you how fast and then how far you're moving

through that fourth dimension. Exactly. And that's all beautiful and wonderful and seems to click together and explains high-velocity experiments and all sorts of things happening across the universe. So it seems right. But quantum mechanics says, I don't agree. I think time is pretty different from that. Right.

Quantum mechanics is a very different view of time, not as a dimension. but maybe as something else. So let's talk about what that quantum view of the universe is and what it would mean to have more dimensions of time. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys.

Then, at 633, 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 two, we're turning on. are focused 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 i'm dr joy harden bradford and in session four 21 of therapy for black girls i sit down with dr ophia 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. 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 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 denial 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 or wherever you get your podcasts have you ever wished for a change but weren't sure how to make it maybe you felt stuck in a job a place or even a relationship i'm emily tish and on-shee pivots, I dive into the inspiring pivots of women who have taken big leaps in their lives and careers.

I'm Gretchen Whitmer, Jody Sweeten, Monica Patton, Elaine Welteroff. I'm Jessica Voss. And that's when I was like, I got to go. I don't know how, but that kicked off the pivot of how to make the transition. Learn how to get comfortable pivoting because your life is going to be full of them. Every episode gets real about the why behind these changes and gives you the inspiration and maybe the push to make your next pivot. Listen to these women and more on She Pivotts, now on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. All right, we're taking the time to talk about time and whether there is more time, because we have lots of time here to talk about these interesting topics.

Are there more dimensions of time? And so we talked about how in special relativity, it's helpful to think of time. as an extra dimension. But actually, quantum mechanics disagrees. It doesn't see time as another possible dimension like the space dimensions. Yeah, in the same way that relativity says, you've been thinking about this all wrong. These two different things, space and time should be thought of as parts of something larger. Quantum mechanic says not so fast. Quantum mechanics says space and time really are very different in important ways and it doesn't make any sense to put them together. And this is an example of how difficult it is to unify these

ideas of quantum mechanics, which are, of course, very, very successful with the ideas of relativity, which are also very, very successful to understand, like, which description of the universe is correct. And one of the issues is that quantum mechanics views time as eternal. You know, quantum mechanics says that the universe has a state, like the particles have a quantum state that can extend through space. That's no problem. And that whole thing like clicks forward in time. So it views time as a way to change the state of the universe. There's like this evolution process where quantum states can slosh from one thing into another thing. So you have your famous equation, the Schrodinger equation, for example, that describes how quantum states

in space can evolve forwards in time. But it treats those things very, very differently. Time and space are very different parts of that equation. Well, time is part of those equations, part of those quantum equations. I think you're just saying that time doesn't stand out as a separate dimension. It just maybe is in there as a separate variable that you think, well, this is totally different than the space dimensions. It's totally different. It has very different properties. For example, quantum mechanics says that information is never destroyed, that the current moment in the universe imprints itself on the future.

So if you have particles bouncing into each other, for example, then what happens to those particles tells you all about the past of the universe. And so this suggests that, you know, information is constant in time. But it's not constant in space. You know, those probabilities don't extend everywhere through space. And it suggests something else really interesting about time. It suggests that time is eternal. Information can never be destroyed.

It means you have the same amount of information forever. Quantum mechanics sees no way around that. It says the universe has to exist forever so that this information can persist. And it must have existed forever somehow so that this information could come to us from the past. So quantum mechanics says like time is so powerful and so basic and so fundamental that the universe itself must be eternal in time. Right. Time is very special according to quantum mechanics.

But it doesn't necessarily mean that it's not. not another dimension or that it's not part of space time or does it? Is there something about what quantum mechanics says that contradicts what special relativity says? That it can't be a part of space time? I think it's possible in the future somehow to unify quantum mechanics and gravity and general relativity into a holistic understanding. So it's not totally impossible. But I'd say that currently quantum mechanics puts space and time on very different footing. You know, another consequence of this is that relativity, for example, which bundles space and time together, says that space and time might have had a beginning.

There could have been a point before the Big Bang when there was no space in time, as hard as that is to even think about, like, a time when there was no time, right? It's sort of contradictory even to say it out loud. But quantum mechanics says the opposite. It all has to do with this idea that information can't be deleted. And so the universe has to be permanent. So that's just an example of how relativity in quantum mechanics could describe very different universes. And that's because quantum mechanics has a very different relationship with time

than it does with space. Whereas relativity bundles them together in a more natural way. Well, I think the question is whether there's something about the two theories that contradict each other. I know they both use time differently or think about time or look at time differently, but is there something sort of inherently contradictory about the two theories about time? I think one of the fundamental differences really is just that relativity views time as almost equivalent to space, whereas quantum mechanics sees them as different and treats them very differently. You know, another example of how quantum mechanics treats space differently is that quantum mechanics doesn't even require space to be fundamental.

You imagine, like, what are the basic elements of the universe? The true theory of physics, what does it contain from which everything else springs? Well, quantum mechanics says space itself doesn't even have to be a necessary part of the universe. You can have a universe without any space. You just have a bunch of quantum states flowing through time without being arranged in this pattern that we think of. of us three-dimensional space. And then space can sort of emerge as these quantum states like weave themselves together into this fabric

that has this sort of adjacency matrix relationship that we find familiar in space. So quantum mechanics allows space itself to like emerge, to not even be a fundamental part of the universe, but still time itself in that picture is fundamental. So I think that's just another illustration of how quantum mechanics views time as fundamentally very different from space.

Well, the weird thing is, is that they're sort of both right or they're both wrong. Like they both are there and they both seem to describe the universe we live in. And so either one of them is right and the other one's wrong or they're both right in a way or in certain ways, right? Or they're both wrong in certain ways. Yeah, they're definitely both wrong in certain ways and both right in certain ways. They're probably just like two different sides of a bigger picture that unifies all of these ideas. And this is what I love about the philosophy of physics is that you're trying to get an understanding of the universe.

You have a mathematical theory that tells you how things work. And then you look at it and you ask, what does that mean? What does that really tell me about how the universe is fundamentally? And these two different theories give us very different pictures of what the universe is, right? What's really going on? And so they can't both be right, you know, because the universe is one thing and no other thing. But we just don't know where that final theory is, the theory of quantum gravity. They would give us a harmonious description of all of this stuff and maybe an understanding deep down of what these things are, space and time.

Okay. So then today we're sort of considering the special relativity viewpoint almost in a way, right? Because we are sort of asking the question if there are more dimensions of time itself. And so I guess what makes us ask this question, Daniel? Why would we question time? We don't question time because we need to. Only because it's fun. Yes, absolutely. It's not like we need it to explain some weird thing we've seen in the universe, right? That's experimentally driven. This is just theoretically driven. This is just like fundamentally me. using about the very nature of the universe. And I think it's fascinating that we have these numbers in physics. You know, space has three dimensions. Why three? Why not two? Why not seven? Why not nine?

Every time you see a number in physics, you have to ask why that number. And that includes when you see just one. So if you say, well, space doesn't have to have just one dimension. We don't live in a one dimensional universe. So if time is also a dimension, why not ask that same question about time? That's really the motivation. That's where it comes from. And also, I mean, we sort of don't really know what time is, as we've been talking about for like 10 minutes.

We like, physicists don't really have a solid concept of what time is. And so you might as well as like, maybe there's more to time than we even think. Absolutely. Time is one of those really basic things we struggle with. There's so many things we don't know about it. Like if it is a dimension, why is it so different from space? You know, why does it only flow forwards? Why can't you go backwards in time?

Why can you only experience every location in time once in your life? But space, you can go back and forth as many times as you like. You know, it seems related to space, obviously, but also fundamentally different. So, yeah, there's basic questions about the nature of time. And sometimes the way to crack these deep mysteries is just ask all the crazy random questions that come into your mind. Like maybe we're missing some slices of time. Maybe we're only seeing one line through a larger dimensional time. Right.

And in fact, there are theories in physics that suggest that maybe there are more dimensions to time, right? Exactly. some of the theories that try to describe the fundamental nature of the universe that we're talking about, the unify quantum mechanics and relativity. Some of these theories like string theory require additional dimensions, usually of space, but some variants of string theory also require additional dimensions of time. And when we say require, we mean that the mathematics works best if the universe has this different property. If the universe has 11 or 26 dimensions, two of which or three of which are time dimensions, then the mathematics of string theory works best.

Right. And so that suggests, and maybe there are more dimensions of time, but Daniel, this is kind of bonkers. Like, how would that even work? It is really hard to think about. And that's what makes it really fun because it challenges you. You know, your brain has been raved in a three plus one universe, three space dimensions and one time dimension. So as hard as it is to think about like a fourth dimension of space, like where would that be? Try to nudge yourself out of your intuition and like let yourself just think mathematically, even harder to think about what it would mean. to have a second dimension of time. You know, one of the challenges in doing that is that in space, we have examples already of multiple dimensions of space.

Like we went through that exercise of thinking about how a 2D person would see a 3D object. And that gives us some intuition for how a 3D person would see a 4D object, right? We know like how to extrapolate. We have the sense for sort of the trend, the directionality of the ideas. But we only have one example of time. And so it's really hard to know how to go from one dimension of time, time to two dimensions of time, right? It's like brain-wise, it's much more difficult. Yeah, my brain is kind of freezing up here just trying to think about it. So let's maybe

paint a picture to our listeners about how it might work. So I'm sitting here in my desk talking to you and time is moving forward in one direction, right? You're saying that maybe like at one point there could be another branch of time. Like maybe the apple I have here in front of me could maybe moving along a separate time axis. And, you know, I would see a decaying. and rod really quickly or something, or instantaneously, maybe. There's a few varieties of what it might mean, but I think the important thing to keep in your mind is if there's another dimension of time, that means that every object has two coordinates.

It's not like I'm along one dimension of time and you're along your own dimension of time, right, where there's both two separate one dimensions of time, but instead think of time as a plane, right? The way you can go from a line to a plane in terms of thinking about space, now try to go from a timeline to a time plane, or every point on that plane has two coordinates in time. So it's like in normal time, it's May 27th, 20203, and in the second dimension of time,

the clocks read something else. And now every point in that plane has a different value for clock one and for clock two. Or another way to say it is now it takes two clocks to specify what time it is. Whoa. Yeah, that's why. like I can have one watch on my left wrist and I can have another watch on my right wrist and they would be, you know, maybe moving at different rates or telling me different times, but I need both of them to sort of know where I am in time.

Yes, exactly. And it allows you to do weird things and we don't even really know how to think about. You have to rely a lot on our intuition for thinking about space. For example, if you're a one deep person, you don't understand what it means to like turn a corner. Whereas in a 2D world, you understand what a corner is. You can have a square and you can walk around it. You can be on one side of it. You can see one side of it and not see another side of it. None of these things you can do in a one-dimensional world.

So try to imagine explaining to a one-dimensional person what it means to turn a corner. They're like, what is that what is that what does that like? Now we are a one-dimensional beings a long time, right? We think that there's one-time dimension. So what does it mean to like turn a corner in two-dimensional, time. Honestly, my brain struggles with the concept. Well, I'm not sure we need to kind of go back to these analogies. Like, I think just having like a left wrist watch and a right wrist watch might be a good way

to kind of illustrate it, right? Like if both my watches are ticking along, that means I'm moving in both time directions at the same time. But if I suddenly see one watch freeze in time, but the other one keep going, that means that I'm right now, then moving through one dimension of time, but not the other. Exactly. And if we're going to have two dimensions of time, remember the role that time plays in physics, it allows things to change. You know, think about a basic equation, F equals MA, there's like velocities in it.

That's the motion of something with respect to time. Now imagine that there's two times in that equation. So those equations are now telling you like how things would evolve if you moved forward in one time or how they would evolve if you move forward in the other time. And maybe they're different, right? Maybe flowing in time one is different than flowing in time two. Then the question is like, how does the universe flow along this plane? Is it a point meandering through this plane in time somehow?

Is it moving just along one time axis? Is it moving along both? Or is it somehow like a line sweeping across this plane? Right. Like somehow the entire universe would be, I guess, moving through both time dimensions at the same time. I think the question is like if my left watch is frozen and I'm moving through time on my right hand watch, that means I'm moving in time in the second dimension.

But let's say you're staying in the first dimension. Like, can we even interact? Like, if we're a different coordinate in time, can you and I still talk? Even if our left watches are synchronized, if our right watches are not synchronized, does that mean we're like in totally different time points? Well, in our universe, you certainly can interact if you're different locations in space and different locations in time. You know, I can send a message to the future.

I can just write something on the wall and somebody later can come read it. I can receive messages from the past, you know, by coming in later and looking at that wall. So you can definitely can communicate. The question of whether you can interact if you're at different points in 2D time depends specifically on the physics of that universe. How do things flow through these two dimensions of time? It actually becomes quite mathematically complicated. People have studied, can you build laws of physics that have two dimensions in time that

makes sense of this? You know, you have a specific thing that's happening, you know, at now comma now for two dimensions of time. And now and then. Yeah. Can you predict what's going to? happen tomorrow comma now versus now comma tomorrow versus tomorrow tomorrow like is the physics actually determined because in our universe we have one dimension of time physics we think about it

as deterministic you know put quantum mechanics aside for a moment we think that if you have a certain situation we have laws of physics that tell you what the future will hold does that also work if you have two dimensions of time which i think is sort of what you're asking you know what are the rules about communicating across time. And people have actually studied this. They've tried to build laws of physics that allow for two dimensions of time. And you run into a lot of trouble, actually.

There's lots of cases where it just doesn't work where the universe can't be self-consistent. Wait, wait, what do you mean? Like something about our equations right now tell us you can't have more than one dimension of time? Most of physics is something we call an initial condition problem. We specify the universe now

and then you run it forward in time. So imagine a bunch of ping pong balls on a table. you know their position, you know their velocity, you can tell exactly where they're going to go and putting quantum mechanics aside for the moment. But what if you have two dimensions of time? That means you need two sets of initial conditions, right? You need to know what happened at time equals zero along time one axis and along time two axis. So instead of like having just a point as initial conditions, now you have this like a line of initial conditions. And some of those things are inconsistent, right? Like you can't always find solutions. Some sets of initial conditions just lead

nonsense. It's like no way to solve the wave equation to be consistent with both sets of initial conditions. And you know, this happens a lot in physics where you just can't find solutions, you know, where you've come up with some system that just like violates Maxwell's equations. And so you don't get a solution where you can figure out like, what is the electric field and the magnetic field in that condition. So if you have two sets of conditions in time, they can contradict each other and lead to inconsistencies. Right. I think what you're saying is that you know the loss of physics the way that we formulated them with the way we've come up with them are sort of there to predict what's going to happen in the future like if I give you a certain

amount of time how is my position in space going to change and so maybe you could have a contradiction where like if I put in this time it tells me that I'm over here but if I put in this other time it tells me that I'm over there and I can't be both places at the same time right I mean I've tried but it usually doesn't work yeah and so people have tried to fix this they said, well, let's not just use the laws of our universe and assume that physics works the same way in 2D time and ask, well, what would we have to add? What extra rules do we need to tack on to the universe to make it work in two-dimensional time? So it gets a little hairy mathematical, but people have found some ways to add constraints and say, well, you can't

just have any initial condition you want. You have some rules about what initial conditions are allowed so that you get solutions that work for both times. So you can run one clock forward or the other clock forward or both and have consistent predictions that make sense. So it is possible then? It's possible if you change fundamentally the way physics works in an interesting way. But what that means is like, you know, maybe the universe is different from the way we thought. If there are two dimensions of time, it means that there's this new sort of rule about how time works that doesn't apply for one dimensional time.

And that's pretty awesome. Well, definitely make making appointments a lot harder. I mean, it's hard enough to coordinate meetings. With one timeline, imagine having to do it in a whole space of time. All right, well, let's get into what other mathematical problems. This idea raises and introduces into physics. And also whether it allows time travel because maybe it does. So let's get into that.

But first, let's take another quick break. 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. Terror. Terrorists. 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 i'm dr joy hardin bradford and in session four 21 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. It's 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. Denial 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.

If a baby is giggling in the back seat, they're probably happy. If a baby is crying in the back seat, they're probably hungry. But if a baby is sleeping in the back seat, will you remember they're even there? When you're distracted, stressed, or not usually the one who drives them, the chances of forgetting them in the back seat are much higher. It can happen to anyone. Parked cars get hot fast and can be deadly. So get in the habit of checking the back seat when you leave.

The message from NHTSA and the Ad Council. We're talking about dimensions of time and whether there are more than one dimensions of our time travels, I guess. Are we actually moving in multiple time dimensions at the same time? It would be really awesome. Man, what a discovery to make to reveal that the universe is so different from the way everybody has ever thought it was. was that's like a real scientific fantasy. That's sort of like the fundamental level of discovery I would love to make. Maybe you already did, Daniel, you know, like in another time, you already did technically.

Maybe I already did slash haven't yet. Yeah, there you go. Maybe you did it, but you went back in time because you realized it was a bad idea. Oh, no. But maybe I'm just doomed to discover it over and over again. Or maybe you did it in a pocket universe, you know, a time pocket. But then you came back to the same time and you had already forgotten. Yeah, maybe the Daniel that makes that dangerous discovery

should be stuffed into one of those mirror universes they have like in Superman. Yeah, a little timeout for physicists. There you go. Instead of cryogenically freezing me, just stuff in an alternate universe. Yeah, there you go. Science gives us lots of options for taking physicists out of commission.

Yeah, or science fiction authors are also parents and they think about timeouts a lot. Well, let's keep talking about time and whether there are more dimensions of it. I guess that's a big question, Daniel. Would having more dimensions of time allow us to travel through time. Actually, I think it's really fun to think about this

because one of my big complaints with time travel movies is that they're fundamentally nonsense. And they're fundamentally nonsense in this really important way that I think a second dimension of time might solve. Right? So most time travel movies have this idea of like a timeline. You know, things happen. You have one dimension of time.

Things are flowing along the timeline. And, you know, in our universe, the timeline is this idea, as you said, earlier that like things can change before you ate lunch and after you ate lunch what's the difference the difference is time time allows things to change but now if you're taking a step out of that you're not on the timeline anymore but you're looking at the timeline and you can see that like the timeline itself doesn't change you describe the history of the universe it's like a certain thing happened at a certain time and then a certain thing happened in later time et cetera

what happens in time travel movies is often that that timeline itself changes right somebody goes off the timeline and loops back to a previous time and changes the timeline and my complaint in those scenarios is always the same is that change requires time there's a time before you made a change in a time after you made the change the same way there's a time before you had lunch and a time after you had lunch so if you're changing the timeline then there's a version of the timeline before you changed it and after you changed it. But along what time dimension is that change happening, right? The timeline itself can't change because change is only along the timeline.

So that's my number one complaint with time travel movies. Maybe that gives you a hint as to how 2D time could solve that. I get also the sense you have many complaints about science switching movies. But I will say, though, that I think, you know, people who write these movies and these shows have gotten pretty complicated. I think they do talk to physicists about these things. And so if you know it is, like, for example, in the Avengers movie, they talk about, they don't talk about timelines changing. They talk about timeline splitting or, you know, like you generate a new timeline that splits off from the original timeline, which doesn't technically change.

It just you split off a new timeline. So they don't really talk about timelines changing. Yeah, I guess it depends. Are you thinking about splitting as a change? Like the timeline was one timeline and then it split into two timelines because that would also be a form of change. Or you could think of them as sort of like the Harry Potter version where like it always has this weird structure where it like forks into multiple versions

in some, you know, double quantum universe thing. But still then people are moving from one timeline to the other. Doesn't that require some kind of like change to the timeline? Well, if you're just jumping between timelines, you don't need to change, right? You can just jump. I mean, it's science fiction. You know, in this, you take a fictional universe. You could just technically change between timelines and not have it change.

Right. But I think what you're saying is the problem is that you can't change a timeline, right? So like even though the Avengers went back in time and save half of the universe, there's still a timeline, a universe where half of the people in the universe are still dead, right? So that doesn't help you much. Yeah, who's thinking about those people, man, like all those folks out there, not able to buy tickets for future Marvel movies because they got Thanos snapped out of existence. Right. Yeah, they lost out in a lot of revenue there. But I think what you're saying is that even though it's something maybe these writers didn't think about is that to change a timeline, like you said, would require time, right, or some sort of change. Yeah. Think about before you change the timeline and after you change the timeline. You know, along what time axis is that happening? Well, the answer is maybe there's a second dimension of time. And in these movies like Back to the Future or whatever, you know, there seems to be this like narrative time, right? You're watching the movie. are flowing through the movie and you're watching the timeline change. That's implicitly another dimension of time, right? And so in this universe, maybe if you have multiple time dimensions, then they're not exactly equivalent the way we were talking about a moment ago, where you have like some plane where you have two coordinates in time

and they're fundamentally equivalent and symmetric in some way. Maybe there are two dimensions of time, but they're different. One like runs along the timeline and the other one allows the timeline itself to change. Right. It's sort of like we talked about before, like if you have two watches, one in your right wrist and one in your left wrist. Like, you know, right now my left wrist watch is synchronized

with the whole universe, right? But maybe I can sort of step out of time, use some of the time in my right watch to maybe go back to a different point. And now I'm in the same universe, but shifted in time in another dimension, in another direction, right? Yeah, like you can use the story time or time two or whatever

to go back and change the original time. and that would allow the timeline to have a previous state and a later state without having some sort of internal conflict. It's like when it was because now you have this other dimension, this additional freedom now, right? Right, but that's basically the same as splitting the timeline, right? It's like the other universe where the half of the people got snapped out of existence is still there.

Like, it's still in the plane of time. But now I'm in a better universe where I actually got to change things. Well, it's still there in the past, yeah. But you've gone back and you've changed the time. So the timeline, according to time two, is no longer the time in which all those people suffer. So, yeah, in the past of this universe, there is a timeline in which those people would have suffered. But in the future of this universe, they don't.

So it's, you know, you've solved the problem in a different way, I think. Right. But I think it sort of goes back to the question I had before. Like, if my left watch and your left watch are synchronized, but my right watch says a different time than your right watch, are we still able to have a regular conversation? or am I even able to shake your hand? Yeah, it just depends on the universe we're in and what rules it follows with respect to time one and time two.

If those are very, very similar and physics respects time one and time two in the same way, then yeah, we can definitely interact. It depends a little bit on the complicated special relativity of three plus two space time. But if it's different, if time one and time two are fundamentally different from each other and the rules for how time two flows are different from time one, then all bets are off. I read a really fun novel by one of my favorite authors, Greg Egan, who's a really creative thinker about how the universe could be different, and it's written great books like Diaspora, which I totally recommend.

And he wrote this book called Dichronauts about a universe that has two spatial dimensions and two time dimensions. So he really takes you through what it would be like to be a dichronaut, a person or a thing living in a universe with two dimensions of time. And he's like, worked out the whole physics of it in his. in his universe, and at least to all these really strange consequences, like sometimes water flows uphill instead of downhill. It's really amazing. Cool. Yeah. Check it out that novel. And I have to say I have tasted cronauts. So those are pretty, pretty tasty. But have you had two of them at the same time.

I don't know about dichronauts. I mean, I get to have two cronuts. It's a cronok, cronuts sandwich. Yeah. I like these two dimensions. All right, but maybe let's get back to physics here. And so I think you're telling me that there's nothing in our current equations or are not. knowledge of the universe that says that you can have more dimensions of time. Like, we could totally have more than one dimension of time. It could be that our universe has more than one dimension of time. On the other hand, there are no hints. It's not like there's any evidence anywhere that requires it.

You know, in some cases, there are things that would be better explained if we had extra dimensions of space, like gravity and large extra dimension theories and all that kind of stuff. There's not even anything about that for time. There's like maybe some versions of string theory that work better with 2D time. But it's really like speculation on speculation. But it is possible. Yes, it's possible that there are two dimensions of time

and that we just haven't noticed the second dimension yet. We don't understand how to experience it. We're like those 2D people living in a 3D universe, not able to look off the plane of our existence and understand this other way of moving or thinking. Right. I guess it could be that it's there, but we just haven't seen it. Or it could be that we are moving through it,

It's just that the way our thinking process works or the way we've somehow formulated our understanding of the universe doesn't, you know, let us see it or maybe we see it all mush together somehow. Exactly. The way that relativity has been in effect well before we discovered it. And it was changing the way the universe worked. We just didn't notice it because the effects were very, very small because of the way that we lived, the speeds and the size of our lives.

And so it could be that the universe has two dimensions of time. We just haven't really revealed it well enough yet. because of the particular way that we are living our lives. Interesting. All right. So the next time I'm late to a meeting, I can just say I was on time and the other time. Can I say that? Can I use physics as an excuse?

You don't even need excuses anymore, man. People just expect it by now. There you go. I've recalibrated the universe to my timeline. It sounds like I want, Daniel. Yeah, I think you really are the center of the universe. But I think it's a fun exercise. You know, for those of you thinking like, this is ridiculous.

it's important to try to push the boundaries. And it might not be that time has two dimensions or any of the theories we talked about today are accurate. But it's an exercise that maybe stumbles along another crazy idea or forces us to invent a new kind of mathematics which stimulates another idea. This sort of like creative theoretical exploration is really, really vital to solving the big questions about the universe.

Yeah, I mean, that's how we discovered a lot of the amazing things we have discovered, right? Like what if the universe is quantized or what if time and space? are malleable. That's the kind of crazy question you have to ask to really find the truth. Yeah, you got to spend some time thinking crazy. All right, well, we hope you had a good time listening to this discussion about time. According to your left watch or your right watch, I think it's time to go. See you next times. More podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. 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. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation. about how to be a better you. When you think about emotion regulation,

you're not going to choose an adaptive strategy which is more effortful to use unless you think there's a good outcome. Avoidance is easier. Ignoring is easier. Denials easier. Complex problem solving. It takes effort.

Listen to the psychology podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Get fired up, y'all. Season two of Good Game with Sarah Spain is underway. We just welcomed one. One of my favorite people, an incomparable soccer icon, Megan Rapino, to the show, and we had a blast. Take a listen.

Sue and I were, like, riding the lime bikes the other day, and we're like, we're like, we. People ride bikes because it's fun. We got more incredible guests like Megan in store, plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports. Network. This is an IHeart podcast.