Daniel and Jorge grapple with the possibility that time could flow in more than one direction, at the same time(s).
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Hey, Jorge, is it time to start the podcast?
My clock says we still have five minutes?
Well, my watch says we're five minutes late. Oh h.
Which one's right? Maybe they're both wrong, or maybe they're both right.
How is that possible?
You're the physicist. 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.
I am Jorhem, a cartoonists and the co author of Frequently Asked Questions about the Universe.
Hi, I'm Daniel. I'm a particle physicist and a professor. You see Irvine and I seem to never have enough time.
Really, I guess professors are pretty busy. Or did you 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 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 get pretty busy. But do you know, as they say, you 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 menage 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 iHeartRadio.
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 all together a big part of space? Time? 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 or 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.
That physic has 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 universe, and sometimes it's kind of hard to comprehend. I mean, and 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 it 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 in nature of space itself, was not the way that we thought it was, was somehow fundamentally different.
Yeah, and we're all about asking crazy fundamental questions, and so 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 time, right, you mean like actual dimensions of time.
Yeah, cartoonist time and physicist time can't actually be brought into a single mathematical framework because one is imaginary. So it's impossible.
Is that the Eisenberg cartoonist physicist uncertainty principle exactly?
That's the do cartoonists actually read their email? Uncertainty principle, which we have pressed to is limits on this project. But this really fun question, and before we dig into it, I'll note that, you know, we actually got to the question of the episode before the ten minute mark, which is something of a record for us. Speaking of total.
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 that just skip the first ten minutes of the podcast. It's mostly us talking about chocolate and bananas.
I have seen those complaints on the on the Alpow 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, there you go.
You can go back in time on a podcast player, so but you can go forward 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 chitchat, 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 twenty six, why not time? And these questions in physics or the 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 have always assumed it to be. From understanding that the universe might be billions of years old instead of thousands, to understand if 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 surprised us many times in the past and hopefully I 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 as having just a single dimension to it right, forwards 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 time outs, 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 cryod chamber. Kids, sh.
Is that a Star Wars reference there? 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 them in their 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 is 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 two questions at Danielandmoorhey dot 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.
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 undimensional because, as for our current understanding physic 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 suggests that it's possible to travel backwards in time, so we only we can only go forward. So yeah, that's that's what I think. It's one dimensional, 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 gonna go with 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 they couldn't your second dimension of time unless there is the multi universe theory and that there's your exexis, which is timing forward. But then there's also this way actually so 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 was timely and right and time.
Well, that's really the goal of this podcast is just to share the joy of having your mind blown and thinking about the universe in a new way. So I love hearing in real time these folks grappling with this crazy and difficult question. Now, 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 to mention, 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 in 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 marble.
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 whole 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, 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 the science fiction definition of a dimension.
Right in 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 slightly different, like the Upside Down and Stranger Things.
Yes, 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 backwards. 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 and 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 hy. 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 another line has a ninety 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. We're talking about our physical universe. Our space feels like it has three D in it because it feels like it's well described mathematically in three dimensions. But you're right, you could potentially have a four D 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 pretty familiar with it, having grown up with it all our lives, where that you can 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, 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. To make more sense, if you bundle them together into some four dimensional object we 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 think about time 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 through, or another thing or another direction that we can move through. And that's kind of true, right, Like we're moving forwards in 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 can combine anything. You know, you could add apples to space and sale 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 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 understand, 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 puts 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 time is a more natural way to think about space or time.
Right, It's like including time as a 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 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 links 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 ten 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 in 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 i'd 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 two D surface, imagine somebody living on a piece of paper. You pass an orange through that piece of paper, it's a three D object. They only see a two D 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 two D circle that's changing in time as you say you're passing a three D 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 three D orange dot appear and grow until it's maximum value, and then shrink back down to do a dot and disappear. So do things that like normal three D objects can't do. So they're reusing fourth dimensional space as an example. As you say, also, sliding through time can give you that same kind of experience. The whole three D space can change with time.
Right, It's almost like if you're sitting there and not moving, you're not moving you through 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, hmm, I don't agree. I think time is pretty different from that.
Right, Quantum mechanics has 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.
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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. Wantum mechanics says, not so fast. Wantum 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. 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 if use time as a way to change the state of the universe, it's like this evolution process where quantum states can slash from one thing into another thing. So you have your famous equation, the Shortener 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. You're just 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 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 would 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 and 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 that 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. Another example of how quantum mechanics treat 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 flow going through time without being arranged in this pattern that we think of as three dimensional space, and then space can sort of emerge as these quantum states like weaved themselves together into this fabric that has this sort of adjacency matrix relationship that we find familiar in space. So quantum mechanics allow space itself to 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 that they're sort of both right or they're both wrong, Like they both are there, 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 us 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 it is that you're trying to get an understanding the universe. You have a mathematical theory that tells you how things work, and then you look at 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 that will 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?
Does he want to.
Only because it's fun? Yes? Absolutely, It's not like we needed to explain some weird thing we've seen in the universe, right, that's experimentally driven. This is just theory hetically driven. This is just like fundamentally musing 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, right.
And also, I mean we sort of don't really know what time is, as we've been talking about for like ten minutes, Like physicists don't really have a solid concept of what time is, and so you might as well ask, 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 experien 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 to 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 and 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, that 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 eleven or twenty six dimensions, two of which are three of which are time dimensions, then the mathematics of strength 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 raised 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 two D person would see a three D object, and that gives us some intuition for how a three D person would see a four D 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 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 decay 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, where every point on that plane has two coordinates in time. So it's like, in normal time, it's May twenty seventh, twenty twenty three, 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 wild. 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 and I have to rely a lot on our intuition for thinking about space. For example, if you're a one D person, you don't understand what it means to like turn a corner right, whereas in a two D 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 into 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 a corner? What does that mean? What is that? What is that? Like? Now, we are 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 wristwatch might be a good way to kind of illustrate it, right, Like, if both both my watches are sticking along, that means I'm moving in both ten 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 the 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. I mean, so 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 co ordinates 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 two D 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 common now for two dimensions.
Of time and now and then, Yeah, can you.
Predict what's going to happen tomorrow common now versus now, Comma tomorrow versus tomorrow com 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 like 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. Right, So, imagine a bunch of ping pong balls on the 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, a long time one axis, and a long time two axis. So instead of like having just a point as initial conditions, now you have this like 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 to nonsense. Is 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 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 in 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 two D time. And they 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 the 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.
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Together, or we're talking about dimensions of time and whether there are more than one dimensions of our or 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. 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.
But maybe I'm just doomed to discover it over and over.
Or maybe you did it in a pocket universe, you know, a time pocket, and 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, yeah, a little time out for physicists.
You go, I think instead of cryogenically freezing me. Just stuff me in an alternate universe.
Yeah, there you go. Nine gives us lots of options for taking physicists out of commission.
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 have 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 time line 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, then 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 at a later time, et cetera, 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 her 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 the change and 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 to mention 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 two D time could solve that.
I get it. Also, the science so 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, and you know, I think they do talk to physicists about these things. And so if you know itice 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 that you know.
This.
Do you take fictional universe? You could just technically change between times and not have a 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 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 on a lot of revenue there. But I think what you're saying is that even though 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 access 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. Things 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 it's a metric 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 like we talked about before, like if you have two watches, one on your right wrist and one in your left risk, Like you know right now my left wrist watch is synchronize with the whole universe, right, But maybe I can sort of step out of time some of the time in my ride 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.
M Like you can use the story time or time too or whatever to go back and change the original time, and that would allow the timeline to have a previous state in a later state without having some sort of internal conflict. It's like when it was because now you have this other dimension. It's 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, that'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 timeline. So the timeline according to time too, 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 the 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 is a different time than your right watch, are we still over 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 that. 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 wrote 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 Dicronots about a universe that has two facial dimensions and two time dimensions, so like really takes you through like what it would be like to be a dichro knot a person or a thing living in a universe with two dimensions of time, and it's like worked out the whole physics of it 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 chronots, so those are pretty pretty tasty.
But have you had two of them at the same time.
I don't know about dikronots. I mean I get to have two kronuts.
It's a krona cronut 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 our 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. Neither 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 two D 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 two D people living in a three D 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 we're you know, it's there, but we just haven't seen it, or it could be that we are moving through 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 to see it. Or maybe we see it all much 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 I was on time in 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.
Let 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 the time has two dimensions or that and 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.
Yep, 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 time.
Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop up of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US Dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit us dairy dot COM's Last Sustainability to learn more.
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