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

0:08
Speaker 1: Or Hey, is it time to start the podcast? My
0:11
Speaker 1: clock says we still have five minutes. Well, my watch
0:14
Speaker 1: says we're five minutes late. Which one's right? Maybe they're
0:17
Speaker 1: both wrong, or maybe they're both right. How is that possible?
0:22
Speaker 1: I know you're the physicist. You tell me something about relativity.
0:26
Speaker 1: Maybe I can't use relativity to understand cartoonists and their
0:30
Speaker 1: slippery relationship with time. Well, there's no time like the present.
0:33
Speaker 1: This is going to take some time. Hi am jorgem
0:51
Speaker 1: made Cartoonists and the co author of Frequently Asked Questions
0:54
Speaker 1: about the Universe. Hi. I'm Daniel. I'm a particle physicist
0:57
Speaker 1: and a professor UC Irvine, and I seem to never
1:00
Speaker 1: ever have enough time. Really, I guess professors are pretty busy.
1:03
Speaker 1: Or did you live in a different space time there
1:06
Speaker 1: in your physics department. Yeah. I try to travel at
1:08
Speaker 1: very high velocities so I can take advantage of time
1:11
Speaker 1: dilation when I'm answering my emails. Oh, I see, you
1:14
Speaker 1: try to write them as fast as possible. Is that
1:16
Speaker 1: how it goes? Like all economics. I'm trying to get
1:18
Speaker 1: as much done in as little time as possible. But
1:22
Speaker 1: you're also quite busy with all of your projects. I
1:24
Speaker 1: am yeah, I'm I get pretty busy. But do you know,
1:27
Speaker 1: as they say, we don't have the time. You gotta
1:29
Speaker 1: make the time. Physicists can make time, right, That's a
1:31
Speaker 1: magic power you guys have. We don't even understand what
1:35
Speaker 1: time is, man not to mention how to make more
1:38
Speaker 1: of it. Well, it's time to tell people. Welcome to
1:40
Speaker 1: our podcast Daniel and Jorge Explain the Universe, a production
1:43
Speaker 1: of I Heart Radio in which we take the time
1:45
Speaker 1: to delve into the deepest mysteries of the universe. How
1:49
Speaker 1: it works, how it flows, what it's fundamental nature is.
1:53
Speaker 1: What are the basic building blocks of this crazy, insane
1:56
Speaker 1: universe that we live in and so thoroughly enjoy, including
2:00
Speaker 1: questions like what is the nature of space itself? How
2:03
Speaker 1: does time flow? Is time part of space? Is space
2:06
Speaker 1: part of time? Is it all together a big part
2:08
Speaker 1: of space? Time? What the heck is going on? Anyway?
2:11
Speaker 1: That's right, because there's no time like the present to
2:13
Speaker 1: study and think about time itself and the present and
2:17
Speaker 1: the future and the past of this crazy and amazing
2:19
Speaker 1: universe that seems to somehow sometimes defy our understanding. I
2:23
Speaker 1: think a lot of people. Imagine that physicists who are
2:26
Speaker 1: trying to understand the universe are working on like really
2:29
Speaker 1: deep difficult questions, questions you wouldn't even understand if you
2:32
Speaker 1: heard somebody say it out loud. But the opposite is true.
2:35
Speaker 1: Physinicesis who are working on the nature or the universe
2:37
Speaker 1: are still asking the same questions that people have been asking.
2:41
Speaker 1: Basically since people have been asking questions, what is space? Anyway?
2:45
Speaker 1: How does time work? Because we've made almost zero progress
2:49
Speaker 1: understanding these basic things about the universe. I thought you
2:53
Speaker 1: were going to say that the opposite is true, that
2:54
Speaker 1: physicists don't actually work. So I thought that was where
2:58
Speaker 1: you were going. You know, like most things that abut philosophy,
3:00
Speaker 1: it's all about your definition of work. That phys has
3:05
Speaker 1: had a very clear definition of what work is. Yeah, exactly,
3:09
Speaker 1: if I'm lying on my couch and I'm not moving
3:11
Speaker 1: in relation to any divorces, am I technically not doing
3:14
Speaker 1: any work? I don't know, but I'm getting paid anyway,
3:17
Speaker 1: So technically the I R S calls it work. So
3:20
Speaker 1: already we're gonna tangle. Yeah, it's called special I R
3:23
Speaker 1: S relativity. I think you can go to jail for
3:26
Speaker 1: that for a relatively long time to Yeah, you can
3:30
Speaker 1: do time in in jail. Also, what do you think
3:33
Speaker 1: about time? But it is an amazing universe and sometimes
3:35
Speaker 1: it's kind of hard to comprehend. I mean, we sort
3:37
Speaker 1: of think we know what's going on. We have some
3:39
Speaker 1: sort of intuition that we have grown up with or
3:42
Speaker 1: have heard about through physics classes and things like that.
3:45
Speaker 1: But as we learn more about the universe, the more
3:47
Speaker 1: it presents challenges for our ability to understand it. And
3:50
Speaker 1: the funnest questions are the most basic ones, the ones
3:53
Speaker 1: that try to dig into the very firmament of our understanding,
3:57
Speaker 1: that like push on the boundaries of the possible, you know,
3:59
Speaker 1: that ask what if the universe was slightly different? What
4:02
Speaker 1: if this basic thing we think is always true about
4:05
Speaker 1: the universe wasn't actually true, or was different or was
4:08
Speaker 1: different here than it is in Alpha Centauri. When I
4:11
Speaker 1: was a kid struggling to wrap my mind around the
4:14
Speaker 1: questions of the universe, this was one of my favorite
4:16
Speaker 1: ones to think about. What if space and time were
4:18
Speaker 1: different in some way? What if the way we moved
4:21
Speaker 1: through space, the very feeling and nature of space itself,
4:24
Speaker 1: was not the way that we thought it was was
4:27
Speaker 1: somehow fundamentally different. Yeah, and we're all about asking crazy
4:31
Speaker 1: fundamental questions, and so today on the podcast we'll be asking,
4:38
Speaker 1: are there two dimensions of time? And Daniel here, you
4:42
Speaker 1: don't mean like cartoonist time and physicist time, right, you
4:45
Speaker 1: mean like actual dimensions of time. Cartoonist time and physicists
4:49
Speaker 1: time can't actually be brought into a single mathematical framework
4:51
Speaker 1: because one is imaginary. So it's impossible. Is that the
4:54
Speaker 1: Eisenberg cartoonist physicists uncertainty principle exactly? That's the two car
5:00
Speaker 1: tune is actually read their email on certainty principle, which
5:03
Speaker 1: we have pressed dos limits on this project. But this
5:06
Speaker 1: really fun question, and before we dig into it, I'll
5:08
Speaker 1: note that, you know, we actually got to the question
5:10
Speaker 1: of the episode before the ten minute mark, which is
5:12
Speaker 1: something of a record for us, speaking of Hey, maybe
5:15
Speaker 1: we're moving in a whole new time dimension right now.
5:18
Speaker 1: I wonder if people are confused, they're like, what they're
5:20
Speaker 1: actually getting to the point exactly. I think there might
5:22
Speaker 1: be folks out there that just skip the first ten
5:24
Speaker 1: minutes of the podcast. It's mostly us talking about chocolate
5:27
Speaker 1: and bananas. I have seen those complaints on the on
5:30
Speaker 1: the Apple reviews. But you know, some people love that
5:33
Speaker 1: bit and some people don't, So hey, skip if you like,
5:36
Speaker 1: don't skip people don't. Yeah, there you go. You can't
5:37
Speaker 1: go back in time on a podcast player, so but
5:40
Speaker 1: you can't go forward in time, so feel free to
5:43
Speaker 1: skip forward if you're not enjoying this anyway, while we
5:45
Speaker 1: celebrate getting to the topic of the podcast without spending
5:48
Speaker 1: too much time at chit chat chatting away all that
5:50
Speaker 1: precious time. Yeah, let's get to it here, Daniel, this
5:53
Speaker 1: is an interesting question. So are there two dimensions of time?
5:56
Speaker 1: I'm like, I wouldn't even have thought to ask this
5:58
Speaker 1: question before an hour ago. Well, that's what's so fun
6:01
Speaker 1: about it, because even the related question are there other
6:04
Speaker 1: dimensions of space? Is one that's hard to grapple with,
6:08
Speaker 1: This idea that space has three dimensions and what if
6:11
Speaker 1: there are more? Right, But now we know there are
6:13
Speaker 1: connections between space and time, and people sometimes think about
6:16
Speaker 1: time itself as a dimension. So if there can be
6:19
Speaker 1: multiple dimensions of space more than three up to twenty six,
6:23
Speaker 1: why not time? And these questions in physics or the
6:27
Speaker 1: philosophy of physics sometimes just start with that, why can't
6:30
Speaker 1: things be this other way? Yeah, it seems nonsense you immediately,
6:34
Speaker 1: but maybe that's just because of the way you've been
6:36
Speaker 1: thinking about the universe. The universe itself doesn't have to
6:39
Speaker 1: obey your restrictions, right. I feel like that's a big
6:42
Speaker 1: part of being a physicist is is sitting around thinking,
6:44
Speaker 1: what if there are more? We need more, bigger, faster,
6:49
Speaker 1: more of them. We definitely do, And that's one of
6:51
Speaker 1: my favorite parts of physics, not just actively sitting around
6:54
Speaker 1: and wondering if the universe could be different, but looking
6:57
Speaker 1: back through the history of physics and finding those more
7:00
Speaker 1: it's those incredible realizations when we discover that the universe
7:03
Speaker 1: actually is quite different from the way we had always
7:06
Speaker 1: assumed it to be. From understanding that the universe might
7:08
Speaker 1: be billions of years old instead of thousands, to understand
7:12
Speaker 1: that the universe could be infinite, to understanding how space
7:15
Speaker 1: and time flow, to figuring out that quantum mechanics rules
7:18
Speaker 1: the microscopic universe. There are all these moments when somebody
7:22
Speaker 1: has finally understood the universe is not the way that
7:25
Speaker 1: we expected it was, And the way to make those
7:27
Speaker 1: discoveries is to keep asking those kinds of questions. Yeah,
7:30
Speaker 1: the universe has surprises of many times in the past
7:33
Speaker 1: and hopefully I also in the future, and especially with
7:36
Speaker 1: this interesting question about whether there are more dimensions of time,
7:39
Speaker 1: because I think most people just assumed there's just one time, right.
7:43
Speaker 1: A lot of people ignore time. There's time zones. But yeah,
7:46
Speaker 1: we mostly imagine that time flows, and that it only
7:49
Speaker 1: flows in one direction, right, and that it can only
7:52
Speaker 1: flow either forwards or backwards, because we think of time
7:56
Speaker 1: as having just a single dimension to it right, forwards
7:59
Speaker 1: and backwards, not like strange plane of time or cube
8:02
Speaker 1: of time or something even crazier. Although I do give
8:05
Speaker 1: my kids a lot of time out, and uh, I
8:08
Speaker 1: think they feel like they're in a separate dimension when
8:10
Speaker 1: they have to wait for it to run out step
8:12
Speaker 1: into the cryod chamber? Kids? Is that a Star Wars
8:18
Speaker 1: reference there to Solo carbonite? Do you think I carbonite
8:21
Speaker 1: my kids? I don't know how you make your choices, man,
8:24
Speaker 1: and I'm not judging anybody's parent game correct. When you
8:26
Speaker 1: say time out, it could mean a lot of things.
8:28
Speaker 1: Oh boy, Yes, I could stick him in the room
8:30
Speaker 1: with like candy and video games. That would be a
8:34
Speaker 1: parenting choice. Yes, I don't want to alienate any of
8:36
Speaker 1: our listeners, but it is an interesting question, and as usual,
8:39
Speaker 1: we were wondering how many people out there had taken
8:41
Speaker 1: the time to think about time in this way and
8:43
Speaker 1: to wonder if there's more than one dimension of time.
8:46
Speaker 1: So thank you very much to everybody who volunteers to
8:49
Speaker 1: answer these weird and wonderful questions about the universe. They
8:53
Speaker 1: give us a sense for what people are thinking and
8:54
Speaker 1: what people already know. We'd love to have you participate
8:58
Speaker 1: for a future episode, so please write to ask two
9:00
Speaker 1: questions at Daniel and Moorhe dot com. Everybody's welcome to
9:04
Speaker 1: think about it for some time. Do you think there
9:07
Speaker 1: is more than one time dimension? Here's what people had
9:11
Speaker 1: to say. There could be more dimensions, more time dimensions
9:14
Speaker 1: the one most likely it can be more than two.
9:18
Speaker 1: But since we can only perceive one, maybe this one
9:24
Speaker 1: that we perceive it has, for instance, the past, the future,
9:30
Speaker 1: and the present. Maybe you can see we can split
9:34
Speaker 1: it in three dimensions. I'm not certain of how the
9:39
Speaker 1: second time commension would work. I'm going to go with maybe,
9:45
Speaker 1: but I can't think of a good way to structure
9:49
Speaker 1: that right now. I believe time is undimensional because, as
9:54
Speaker 1: for our current understanding, physiquets theoretically possible to travel forward
9:58
Speaker 1: in time if you try really at the speed of
10:01
Speaker 1: light a little to something. But I don't see any
10:05
Speaker 1: theories that suggests that it's possible to travel backwards same time.
10:10
Speaker 1: So we can only go forward. So yeah, that's that's
10:14
Speaker 1: what I think. It's one dimension, So I guess forward
10:17
Speaker 1: and back would be one dimension. So two dimensions is
10:22
Speaker 1: like a sheet of paper. That is very hard to
10:26
Speaker 1: think about. Um, I'm just gonna go off. No, it
10:30
Speaker 1: doesn't make any sense to me. Oh, I think so.
10:33
Speaker 1: I think that would be really cool, and I don't
10:35
Speaker 1: know what it means, though, I would say there couldn't
10:37
Speaker 1: be a second dimension of time unless there is the
10:40
Speaker 1: multi universe theory and that there's your exexes, which is
10:44
Speaker 1: timing forward. But then there's also the way acts of
10:46
Speaker 1: many different times moving forward. Um, but if that's not
10:50
Speaker 1: the case, I'd say, no, there's only one dimension of time.
10:53
Speaker 1: All right. Some interesting answers here. How much time do
10:55
Speaker 1: you think people spend thinking about this answer? I don't know,
10:58
Speaker 1: but I think it increased the fraction of their lives
11:00
Speaker 1: where their minds were blown, which I'm sure it was
11:05
Speaker 1: timely and right in time. Well, that's really the goal
11:08
Speaker 1: of this podcast is just to share the joy of
11:11
Speaker 1: having your mind blown, of thinking about the universe in
11:13
Speaker 1: a new way. So I love hearing in real time
11:16
Speaker 1: these folks grappling with this crazy and difficult question that
11:20
Speaker 1: I totally admit I have trouble with. Also, well, a
11:22
Speaker 1: lot of people here seem to think that there couldn't
11:24
Speaker 1: be more than one time to mention. I mean, we
11:27
Speaker 1: we're sort of used to the past and the present
11:29
Speaker 1: and that's it. But I like this answer here that
11:30
Speaker 1: says that maybe in a multiverse there is more than
11:33
Speaker 1: one time, right, Like each universe would have its own time,
11:36
Speaker 1: if there is a multiverse, Yeah, in the sense that
11:38
Speaker 1: each universe would have its own space and its own time.
11:41
Speaker 1: I think this question is more about whether our particular universe,
11:44
Speaker 1: our space time, has more than one time dimensioned. You know,
11:48
Speaker 1: if there are other universes out there that have their
11:50
Speaker 1: own space, that doesn't like give you a new way
11:52
Speaker 1: to move left, right, up, down, forward, backwards. So that
11:56
Speaker 1: seems to me like a bit of a marble loophole, which,
12:00
Speaker 1: as we know, are terrible ideas because they don't make
12:02
Speaker 1: any money at all. But it is a sort of
12:06
Speaker 1: a loople that you didn't quite a specify in your
12:08
Speaker 1: question though, So technically they could be right, yeah, push
12:11
Speaker 1: the boundaries people exactly think creatively. It was Kevin Figy,
12:15
Speaker 1: the producer at Marvel who that will phone in with
12:17
Speaker 1: that answer. Kevin, give us a call. We'd love to
12:21
Speaker 1: have you on the podcast. But it is interesting to
12:23
Speaker 1: think that maybe there is not just the one time
12:26
Speaker 1: that we have here in our universe. There could be
12:28
Speaker 1: maybe more time dimensions. And so Daniel, let's step through
12:32
Speaker 1: this for people, and let's start with the basics. What
12:34
Speaker 1: exactly is a dimension? Right? Dimension is one of the
12:38
Speaker 1: most misused words in science fiction. You see it all
12:41
Speaker 1: the time, people traveling to another dimension. And when they
12:45
Speaker 1: say dimension in science fiction, really they mean some other universe,
12:49
Speaker 1: some complete other existence, maybe with different rules of physics,
12:53
Speaker 1: different space, maybe different time, whatever, different crazy beings covered
12:56
Speaker 1: in Marshmallows, who knows what. It's sort of just like somewhere.
13:00
Speaker 1: But that's not the physics definition of a dimension. That's
13:03
Speaker 1: the science fiction definition of a dimension. Right. In sci
13:06
Speaker 1: fi movies and TV shows, they always like open a
13:08
Speaker 1: door into another dimension and you step through it and
13:10
Speaker 1: it's like you're in a different version of your universe,
13:13
Speaker 1: but it's it's like slightly different, like the Upside Down
13:15
Speaker 1: and Stranger Things. Yes, Stranger Things is a great example
13:19
Speaker 1: of another location, and they don't actually call it a
13:22
Speaker 1: dimension in Stranger Things, which I like. But that's sort
13:24
Speaker 1: of like the concept people have in their mind of
13:26
Speaker 1: another dimension. But when physicist talking about a dimension, they
13:29
Speaker 1: just mean a direction that you can move in. So
13:32
Speaker 1: our space has three dimensions to it. If you draw
13:36
Speaker 1: a straight line through space, you can move along that line.
13:39
Speaker 1: Maybe that line is like forwards and backwards. Now draw
13:42
Speaker 1: another line that's perpendicular to that line. That's another direction
13:46
Speaker 1: you can move in. And because you've made them perpendicular,
13:48
Speaker 1: motion in one is independent from motion in the other.
13:51
Speaker 1: Like if you have now have two lines X and Y,
13:54
Speaker 1: you can completely describe the location anywhere on a two
13:58
Speaker 1: dimensional plane, and emotion in X can change your motion
14:01
Speaker 1: in Wise, you really need two dimensions to describe a plane,
14:06
Speaker 1: and then there's a third dimension you can add, which
14:08
Speaker 1: is perpendicular to both X and Y, called it Z.
14:11
Speaker 1: For example, maybe the up and down so we have
14:13
Speaker 1: three dimensions of space that we're aware of, and you
14:16
Speaker 1: can't add a fourth there's no way to add another
14:19
Speaker 1: line has a ninety degree angle to x and y
14:22
Speaker 1: and z. There isn't like room for it in our
14:24
Speaker 1: space that we're aware of. Well, there's no room for
14:27
Speaker 1: it in three dimensional space for a fourth dimension by definition, right,
14:31
Speaker 1: But that doesn't mean it's not mathematically possible. It is
14:34
Speaker 1: mathematically possible to create four dimensional spaces. So we're talking
14:37
Speaker 1: about our physical universe. Our space feels like it has
14:40
Speaker 1: three D in it because it feels like it's well
14:42
Speaker 1: described mathematically in three dimensions. But you're right, you could
14:46
Speaker 1: potentially have a four D space, and mathematicians have no
14:49
Speaker 1: limit to the number of dimensions they can imagine. It's
14:51
Speaker 1: hard to sort of grapple with and have a visual
14:54
Speaker 1: of it. But in a four dimensional space, there is
14:56
Speaker 1: another dimension which is perpendicular to all the other three,
15:00
Speaker 1: meaning that there's some way you can move, some direction
15:03
Speaker 1: you can slide in that isn't described by the previous
15:06
Speaker 1: three dimensions. There's like version of this three dimensional space,
15:09
Speaker 1: and then you move along that fourth dimension, there's another
15:11
Speaker 1: version of that three dimensional space. So space really has
15:14
Speaker 1: like another digit to it, right, So that's three dimensional space,
15:18
Speaker 1: and I think we're all, you know, pretty familiar with it,
15:20
Speaker 1: having grown up with it all our lives, where that
15:23
Speaker 1: you can, you know, move forward and backwards and up
15:25
Speaker 1: and down and left and right, and they're all sort
15:27
Speaker 1: of independent. But then there's also the idea that maybe
15:29
Speaker 1: time is a dimension, right, and in fact, that maybe
15:32
Speaker 1: time is like a brother or a sister to the
15:35
Speaker 1: space dimensions. Yeah, it's a really fun idea and it's
15:38
Speaker 1: really sort of mathematically beautiful, but it's not something that
15:41
Speaker 1: physicists really understand, and it goes to the heart of
15:44
Speaker 1: one of the biggest conflicts and open problems in modern physics,
15:48
Speaker 1: which is who's correct quantum mechanics or relativity, Because these
15:52
Speaker 1: two theories, which are like the pillars of physics, have
15:55
Speaker 1: different views about what time is and whether it's a
15:59
Speaker 1: dimension in the way that space is. So let's start
16:02
Speaker 1: with relativity, because relativity is the idea that connects space
16:06
Speaker 1: and time really intimately. It says, like, you know, space
16:09
Speaker 1: by itself and time by itself don't really make sense
16:11
Speaker 1: to think about independently. To make more sense if you
16:15
Speaker 1: bundle them together into some four dimensional object we call
16:18
Speaker 1: space time. So you take the three dimensions of space
16:22
Speaker 1: and you add time to it. You have this now
16:24
Speaker 1: mathematically four dimensional construct which you can treat as if
16:29
Speaker 1: it was a four dimensional space time. Right. That happens
16:32
Speaker 1: in the math where you just kind of like add
16:33
Speaker 1: another you know, space in your vectors to to think
16:36
Speaker 1: about time. But in a sort of interesting way, it
16:40
Speaker 1: sort of kind of means that time is sort of
16:43
Speaker 1: another way that we can move, or another thing or
16:46
Speaker 1: another direction that we can move through. And that's kind
16:49
Speaker 1: of true, right, Like we're moving forwards and time as
16:52
Speaker 1: if we were moving along direction there we are moving
16:56
Speaker 1: along a time access. And that's why mathematically it's sort
17:00
Speaker 1: of possible to combine these things. I think it's also
17:03
Speaker 1: worth spending a moment thinking about, like why you would
17:05
Speaker 1: do that, How do you justify that? Because in principle,
17:07
Speaker 1: you can combine anything. You know, you could add apples
17:10
Speaker 1: to space, and so I have now an apple dimension
17:12
Speaker 1: or something counts the number of apples in the universe.
17:15
Speaker 1: Like that doesn't necessarily make sense or give you any
17:17
Speaker 1: extra explanatory power about the universe, but adding space and
17:21
Speaker 1: time together really does It's one of these examples where
17:24
Speaker 1: we see two separate things, neither of which makes sense
17:27
Speaker 1: completely on their own, but when you both them together,
17:30
Speaker 1: you suddenly get a crisper view, a simpler understanding. You know,
17:33
Speaker 1: it's like seeing two sides of a coin and thinking
17:35
Speaker 1: they're totally separate and then understanding, oh, these are two
17:38
Speaker 1: sides of the same thing. Or how we knew about
17:41
Speaker 1: electricity and magnetism and there were things that didn't really
17:43
Speaker 1: quite make sense until we put them together and say, actually,
17:46
Speaker 1: this is just one thing, and we have a simpler
17:49
Speaker 1: set of equations that describe electro magnetism instead of trying
17:53
Speaker 1: to think about these things separately. In the same way,
17:55
Speaker 1: when Einstein puts space and time together, a lot of
17:58
Speaker 1: things got much simple learn In terms of the mathematics,
18:01
Speaker 1: a lot of symmetries are obeyed by space time that
18:04
Speaker 1: are not obeyed by space or by time separately. So
18:08
Speaker 1: that's the that's the thing that makes relatives. People who
18:10
Speaker 1: believe relativity is the foundational explanation of the universe convinced
18:14
Speaker 1: that space time is a more natural way to think
18:16
Speaker 1: about space or time. Right. It's like including time as
18:20
Speaker 1: the dimension in the equations. Makes the equations kind of
18:23
Speaker 1: click right like, it makes them makes sense because there
18:25
Speaker 1: are some transformations like s in the math, and when
18:28
Speaker 1: you're trying to do physics, that just makes sense if
18:30
Speaker 1: you also include time as a dimension. Yeah, we know
18:33
Speaker 1: from relativity that time is not universal. You know that
18:36
Speaker 1: depending on who's looking at the clock and their velocity
18:39
Speaker 1: relative to it, it flows differently. And the same is
18:41
Speaker 1: true of space that people who try to measure distances
18:44
Speaker 1: and lengths, it depends weirdly on who you are, where
18:47
Speaker 1: you are, and how fast you are going. But if
18:49
Speaker 1: you combine these things, space and time together, then you
18:52
Speaker 1: get a lot of invariants things that everybody can agree on.
18:55
Speaker 1: If you just talk about where you are in space
18:57
Speaker 1: time rather than just talking about where you are space,
19:00
Speaker 1: we're just talking about where you are in time. And
19:02
Speaker 1: you're right, fundamentally time can be viewed as a dimension
19:05
Speaker 1: there because you're moving through it. You have a coordinate.
19:08
Speaker 1: Now is a coordinate in time? Now plus ten seconds
19:12
Speaker 1: is a coordinate further along that access. So if you'd
19:15
Speaker 1: like to think about dimensions, is like these glowing arrows
19:18
Speaker 1: through space telling you where you are, like grid lines
19:21
Speaker 1: on a map. You can also do the same thing
19:22
Speaker 1: for time and think about it as a coordinate of
19:25
Speaker 1: that time dimension, right and time. I think we sometimes
19:28
Speaker 1: use it as a good way to to sort of
19:29
Speaker 1: illustrate what it would be like to move in higher
19:32
Speaker 1: dimensional space, like if maybe space had four dimensions, like
19:35
Speaker 1: time is what that extra dimension might feel like. Right, Like,
19:38
Speaker 1: I'm here sitting on my desk in one point in
19:40
Speaker 1: through dimensional space. But at the same time, I'm sort
19:43
Speaker 1: of moving without thinking about it, moving through another dimension
19:47
Speaker 1: that's independent of those three dimensions. But it's like I'm
19:50
Speaker 1: moving through time, which means I'm moving through that dimension. Yeah. Absolutely.
19:54
Speaker 1: You know, if you think about like somebody on a
19:56
Speaker 1: two D surface, imagine somebody living on a piece of paper.
19:58
Speaker 1: You pass an orange through that piece of paper, it's
20:01
Speaker 1: a three D object. They only see a two D
20:03
Speaker 1: slice of it. What do they see? They see a
20:05
Speaker 1: dot appear, Then that dot grows into a circle, and
20:08
Speaker 1: then it shrinks back into a dot. So they're seeing
20:11
Speaker 1: a two D circle that's changing in time. As you say,
20:14
Speaker 1: if you're passing a three D object through the plane.
20:17
Speaker 1: Now in our world, if somebody passed a four dimensional
20:20
Speaker 1: orange through your kitchen what would you see. You would
20:23
Speaker 1: see a three D orange dot appear and grow until
20:27
Speaker 1: it's maximum value, and then shrink back down to do
20:29
Speaker 1: a dot and disappear. So do things that like normal
20:32
Speaker 1: three D objects can't do. So they are we using
20:35
Speaker 1: fourth dimension of space as an example. As you say,
20:37
Speaker 1: also sliding through time can give you that same kind
20:40
Speaker 1: of experience. The whole three D space can change with time. Right,
20:43
Speaker 1: It's almost like if you're sitting there and not moving,
20:46
Speaker 1: you're not moving you through dimensional space, but your clock,
20:48
Speaker 1: your watch is telling you how fast and then how
20:51
Speaker 1: far you're moving through that fourth dimension exactly, and that's
20:54
Speaker 1: all beautiful and wonderful. It seems to click together and
20:56
Speaker 1: explains high velocity experiments and all sorts of things happening
21:00
Speaker 1: across the universe. So it seems right. But quantum mechanics says, hmmm,
21:04
Speaker 1: I don't agree. I think time is pretty different from that, right,
21:07
Speaker 1: Quantum mechanics is a very different view of time, not
21:09
Speaker 1: as a dimension, but maybe as something else. So let's
21:12
Speaker 1: talk about what that quantum view of the universe is
21:14
Speaker 1: and what it would mean to have more dimensions of time.
21:18
Speaker 1: But first let's take a quick break all right, we're
21:33
Speaker 1: taking the time to talk about time and whether there
21:36
Speaker 1: is more time because we have lots of time here
21:38
Speaker 1: to talk about these interesting topics. Are there more dimensions
21:41
Speaker 1: of time? And so we talked about how in special
21:43
Speaker 1: relativity it's helpful to think of time as an extra dimension,
21:47
Speaker 1: but actually quantum mechanics disagrees. It doesn't see time as
21:51
Speaker 1: another possible dimension like the space dimensions. Yeah, and the
21:54
Speaker 1: same way that relativity says, you've been thinking about this
21:57
Speaker 1: all wrong. These two different things, space and time should
22:01
Speaker 1: be thought of as parts of something larger. Quantum mechanics says,
22:04
Speaker 1: not so fast. Quantum mechanics says, space and time really
22:08
Speaker 1: are very different in important ways, and it doesn't make
22:10
Speaker 1: any sense to put them together. And this is an
22:13
Speaker 1: example of how difficult it is to unify these ideas
22:16
Speaker 1: of quantum mechanics, which are of course very very successful,
22:19
Speaker 1: with the ideas of relativity, which are also very very successful,
22:23
Speaker 1: to understand like which description of the universe is correct.
22:26
Speaker 1: And one of the issues is that quantum mechanics views
22:28
Speaker 1: time as eternal. You know, quantum mechanics says that the
22:32
Speaker 1: universe has a state like the particles have a quantum
22:35
Speaker 1: state that can extend through space, that's no problem, and
22:38
Speaker 1: that whole thing like clicks forward in time. So it
22:41
Speaker 1: used time as a way to change the state of
22:43
Speaker 1: the universe. Is like this evolution process where quantum states
22:47
Speaker 1: can slash from one thing into another thing. So you
22:50
Speaker 1: have your famous equation, the shorting their equation for example,
22:53
Speaker 1: that describes how quantum states in space can evolve forwards
22:57
Speaker 1: in time, but it treats those things very very different.
23:00
Speaker 1: Time and space are very different parts of that equation.
23:03
Speaker 1: What time is it part of those equations, part of
23:05
Speaker 1: those quantum equations. You're just I think you're just saying
23:07
Speaker 1: that time doesn't stand out as a separate dimension. It
23:10
Speaker 1: just maybe is in there as a separate variable that
23:13
Speaker 1: you think, well, this is totally different than the space dimensions.
23:16
Speaker 1: It's totally different. It has very different properties. For example,
23:18
Speaker 1: quantum mechanics says that information is never destroyed, that the
23:22
Speaker 1: current moment in the universe imprints itself on the future.
23:25
Speaker 1: So if you have particles bouncing into each other, for example,
23:28
Speaker 1: then what happens to those particles tells you all about
23:30
Speaker 1: the past of the universe. And so this suggests that
23:33
Speaker 1: you know information is constant in time, but it's not
23:37
Speaker 1: constant in space. You know, those probabilities don't extend everywhere
23:40
Speaker 1: through space. And it suggests something else really interesting about time.
23:44
Speaker 1: It suggests that time is eternal. Information can never be destroyed.
23:47
Speaker 1: It means you have the same amount of information forever.
23:50
Speaker 1: Quantum mechanics sees no way around that. It says the
23:52
Speaker 1: universe has to exist forever so that this information can persist,
23:56
Speaker 1: and it must have existed forever somehow so that this
23:59
Speaker 1: in formation could come to us from the past. So
24:02
Speaker 1: quantum mechanics says, like time is so powerful and so
24:05
Speaker 1: basic and so fundamental that the universe itself must be
24:08
Speaker 1: eternal in time. Right. Time is very special according to
24:11
Speaker 1: quantum mechanics. But it doesn't necessarily mean that it's not
24:14
Speaker 1: another dimension, or that it's not part of space time,
24:16
Speaker 1: or does it? Is there something about what quantum mechanics
24:19
Speaker 1: says that contradicts what special relativity says that it can't
24:23
Speaker 1: be a part of space time. I think it's possible
24:25
Speaker 1: in the future somehow to unify quantum mechanics and gravity
24:29
Speaker 1: and general relativity into a holistic understanding. So it's not
24:32
Speaker 1: totally impossible, But I would say that currently quantum mechanics
24:36
Speaker 1: puts space and time on very different footing. You know.
24:38
Speaker 1: Another consequence of this is that relativity, for example, which
24:42
Speaker 1: bundles space and time together, says that space and time
24:45
Speaker 1: might have had a beginning. There could have been a
24:47
Speaker 1: point before the Big Bang when there was no space
24:50
Speaker 1: and time. As hard as that it is to even
24:51
Speaker 1: think about, like a time when there was no time, right,
24:54
Speaker 1: it's sort of contradictory even to say it out loud.
24:56
Speaker 1: But quantum mechanics says the opposite. And it all has
24:59
Speaker 1: to do with this idea. Information can't be deleted, and
25:01
Speaker 1: so the universe has to be permanent. So that's just
25:04
Speaker 1: an example of how relativity and quantum mechanics could describe
25:07
Speaker 1: very different universes. And that's because quantum mechanics has a
25:11
Speaker 1: very different relationship with time than it does with space,
25:14
Speaker 1: whereas relativity bundles them together in a more natural way. Well,
25:18
Speaker 1: I think the question is whether there's something about the
25:21
Speaker 1: two theories that contradict each other. I know they both
25:24
Speaker 1: used time differently, or think about time or look at
25:27
Speaker 1: time differently, but is there something sort of inherently contradictory
25:30
Speaker 1: about the two theories that about time. I think one
25:32
Speaker 1: of the fundamental differences really is just that relativity views
25:36
Speaker 1: time is almost equivalent to space, whereas quantum mechanics sees
25:39
Speaker 1: them as different and treats them very differently. Another example
25:43
Speaker 1: of how quantum mechanics treats space differently is that quantum
25:46
Speaker 1: mechanics doesn't even require space to be fundamental. And you imagine, like,
25:50
Speaker 1: what are the basic elements of the universe, the true
25:53
Speaker 1: theory of physics, what does it contain from which everything
25:55
Speaker 1: else springs. Well, quantum mechanics says, space itself doesn't even
26:00
Speaker 1: have to be a necessary part of the universe. You
26:03
Speaker 1: can have a universe without any space. You just have
26:05
Speaker 1: a bunch of quantum states flowing through time without being
26:09
Speaker 1: arranged in this pattern that we think of us three
26:12
Speaker 1: dimensional space, and then space can sort of emerge as
26:16
Speaker 1: these quantum states, like we've themselves together into this fabric
26:20
Speaker 1: that has this sort of adjacency matrix relationship that we
26:23
Speaker 1: find familiar in space. So quantum mechanics allows space itself
26:27
Speaker 1: to like emerge, to not even be a fundamental part
26:29
Speaker 1: of the universe, but still time itself in that picture
26:33
Speaker 1: is fundamental. So I think that's just another illustration of
26:36
Speaker 1: how quantum mechanics views time is fundamentally very different from space. Well,
26:41
Speaker 1: the weird thing is that they're sort of both right
26:43
Speaker 1: or they're both wrong, Like they both are there and
26:46
Speaker 1: they both neem to describe the universe we live in.
26:48
Speaker 1: And so either one of them is right and the
26:50
Speaker 1: other one's wrong, or they're both a right in a
26:52
Speaker 1: in a way or in certain ways right, or they're
26:55
Speaker 1: both wrong in certain ways. Yeah, they're definitely both wrong
26:57
Speaker 1: in certain ways and both right in certain ways. They're
27:00
Speaker 1: probably just like two different sides of a bigger picture
27:03
Speaker 1: that unifies all of these ideas. And this is what
27:06
Speaker 1: I love about the philosophy of physics is that you're
27:08
Speaker 1: trying to get an understanding the universe. You have a
27:10
Speaker 1: mathematical theory that tells you how things work, and then
27:13
Speaker 1: you look at and you ask what does that mean?
27:15
Speaker 1: What does that really tell me about how the universe
27:18
Speaker 1: is fundamentally And these two different theories give us very
27:20
Speaker 1: different pictures of what the universe is right, what's really
27:23
Speaker 1: going on? And so they can't both be right, you know,
27:27
Speaker 1: because the universe is one thing and no other thing.
27:29
Speaker 1: But we just don't know where that final theory is,
27:31
Speaker 1: the theory of quantum gravity, that we give us a
27:33
Speaker 1: harmonious description of all of this stuff and maybe an
27:37
Speaker 1: understanding deep down of what these things are space and time. Okay,
27:41
Speaker 1: So then today we're sort of considering the special relativity
27:43
Speaker 1: viewpoint almost in a way, right, because we are sort
27:46
Speaker 1: of asking the question if there are more dimensions of
27:49
Speaker 1: time itself? And so I guess what makes us ask
27:51
Speaker 1: this question, Daniel? Why would we question time? We don't
27:54
Speaker 1: question time because we need to, only because you want to,
27:58
Speaker 1: only because it's fine. And yes, absolutely, it's not like
28:02
Speaker 1: we needed to explain some weird thing we've seen in
28:04
Speaker 1: the universe, right, that's experimentally driven. This is just theoretically driven.
28:08
Speaker 1: This is just like fundamentally musing about the very nature
28:12
Speaker 1: of the universe. And I think it's fascinating that we
28:14
Speaker 1: have these numbers in physics. You know, space has three dimensions?
28:18
Speaker 1: Why three? Why not to? Why not seven? Why not nine?
28:22
Speaker 1: Every time you see a number in physics you have
28:24
Speaker 1: to ask why that number? And that includes when you
28:27
Speaker 1: see just one. So if you say, well, space doesn't
28:30
Speaker 1: have to have just one dimension. We don't live in
28:32
Speaker 1: a one dimensional universe. So if time is also a dimension,
28:35
Speaker 1: why not ask that same question about time? That's really
28:38
Speaker 1: the motivation, that's where it comes right. And also, I mean,
28:41
Speaker 1: we sort of don't really know what time is, as
28:43
Speaker 1: we've been talking about for like ten minutes. We like
28:45
Speaker 1: the physics don't really have a solid concept of what
28:48
Speaker 1: time is, and so you might as well ask, like,
28:51
Speaker 1: maybe there's more to time than we even think. Absolutely,
28:54
Speaker 1: time is one of those really basic things we struggle with.
28:56
Speaker 1: There's so many things we don't know about it, like
28:59
Speaker 1: if it is a dimension, and why is it so
29:01
Speaker 1: different from space? You know, why does it only flow forwards?
29:05
Speaker 1: Why can't you go backwards in time? Why can you
29:07
Speaker 1: only experience every location in time once in your life,
29:10
Speaker 1: but space you can go back and forth as many
29:12
Speaker 1: times as you like. You know. It seems related to
29:15
Speaker 1: space obviously, but also fundamentally different. So yeah, there's basic
29:19
Speaker 1: questions about the nature of time, and sometimes the way
29:21
Speaker 1: to crack these deep mysteries is just ask all the
29:24
Speaker 1: crazy random questions that come into your mind, like maybe
29:27
Speaker 1: we're missing some slices of time, maybe we're only seeing
29:31
Speaker 1: one line through a larger dimensional time, right, And in fact,
29:34
Speaker 1: there are theories in physics that suggest that maybe there
29:37
Speaker 1: are more dimensions to time, right exactly. Some of the
29:40
Speaker 1: theories that try to describe the fundamental nature of the
29:42
Speaker 1: universe that we're talking about the unify quantum mechanics and relativity.
29:46
Speaker 1: Of these theories, like string theory, require additional dimensions, usually
29:50
Speaker 1: of space, but some variants of string theory also require
29:53
Speaker 1: additional dimensions of time. And when we say require, we
29:56
Speaker 1: mean that the mathematics works best if the universe has
30:00
Speaker 1: is different property. If the universe has eleven or twenty
30:03
Speaker 1: six dimensions, two of which are three of which our
30:05
Speaker 1: time dimensions, then the mathematics of string theory works best, right,
30:09
Speaker 1: And so that suggests and maybe there are more dimensions
30:12
Speaker 1: of time. But Daniel, this is kind of bonkers, like
30:14
Speaker 1: how would that even work? It is really hard to
30:16
Speaker 1: think about, and that's what makes it really fun because
30:18
Speaker 1: it challenges you. You know, your brain has been raised
30:21
Speaker 1: in a three plus one universe, three space dimensions and
30:24
Speaker 1: one time dimension. So as hard as it is to
30:27
Speaker 1: think about like a fourth dimension of space, like where
30:30
Speaker 1: would that be? Try to nudge yourself out of your
30:32
Speaker 1: intuition and like let yourself just think mathematically even harder
30:37
Speaker 1: to think about what it would mean to have a
30:39
Speaker 1: second dimension of time. You know. One of the challenges
30:42
Speaker 1: in doing that is that in space, we have examples
30:45
Speaker 1: already of multiple dimensions of space. Like we went through
30:48
Speaker 1: that exercise of thinking about how a two D person
30:51
Speaker 1: would see a three D object, and that gives us
30:53
Speaker 1: some intuition for how a three D person would see
30:56
Speaker 1: a four D object. Right, we know like how to extrapolate.
31:00
Speaker 1: We have a sense for sort of the trend the
31:02
Speaker 1: directionality of the ideas, but we only have one example
31:05
Speaker 1: of time, and so it's really hard to know how
31:07
Speaker 1: to go from one dimension of time to two dimensions
31:10
Speaker 1: of time. Right, It's like, brain wise, it's much more difficult. Yeah,
31:14
Speaker 1: my my brain is kind of freezing up here just
31:16
Speaker 1: trying to think about it. So I let's maybe paint
31:19
Speaker 1: the picture to our listeners about how it might work.
31:21
Speaker 1: So I'm sitting here in my desk talking to you,
31:24
Speaker 1: and time is moving forward in one direction. Right. You're
31:28
Speaker 1: saying like, maybe like at one point there could be
31:30
Speaker 1: another branch of time, Like maybe the apple I have
31:34
Speaker 1: here in front of me could maybe moving along as
31:36
Speaker 1: separate time axes, and you know, I would see a
31:39
Speaker 1: decay and rod really quickly or something or instantaneously. Maybe
31:42
Speaker 1: there's a few varieties of what it might mean, but
31:44
Speaker 1: I think the important thing to keep in your mind
31:46
Speaker 1: is if there's another dimension of time that means that
31:49
Speaker 1: every object has two coordinates. It's not like I'm along
31:53
Speaker 1: one dimension of time and you're along your own dimension
31:56
Speaker 1: of time right where there's both two separate one dimensions
31:59
Speaker 1: of time, and instead to think of time as a plane,
32:02
Speaker 1: right the way you can go from a line to
32:05
Speaker 1: a plane in terms of thinking about space. Now, try
32:07
Speaker 1: to go from a timeline to a time plane where
32:10
Speaker 1: every point on that plane has two coordinates in time.
32:14
Speaker 1: So it's like in normal time, it's May two thousand
32:18
Speaker 1: twenty three, and in the second dimension of time, the
32:20
Speaker 1: clocks read something else. And now every point in that
32:24
Speaker 1: plane has a different value for clock one and for
32:27
Speaker 1: clock two, or another way to say it is now
32:29
Speaker 1: it takes two clocks to specify what time it is. WHOA, Yeah,
32:35
Speaker 1: that's wild. Like I can have one watch on my
32:37
Speaker 1: left wrist and I can have another watch on my
32:41
Speaker 1: right wrist, and they would be, you know, maybe moving
32:43
Speaker 1: at different rates or telling me different times, but I
32:46
Speaker 1: need both of them to sort of know where I
32:48
Speaker 1: am in time, Yes, exactly, And it allows you to
32:52
Speaker 1: do weird things. And we don't even really know how
32:55
Speaker 1: to think about and have a lot rely a lot
32:57
Speaker 1: on our intuition for thinking about space. For example, if
33:00
Speaker 1: you're a one deep person, you don't understand what it
33:03
Speaker 1: means to like turn a corner, right, Whereas in a
33:06
Speaker 1: two D world you understand what a corner is. You know,
33:09
Speaker 1: you can have a square and you can walk around it,
33:11
Speaker 1: you can be on one side of it, you can
33:13
Speaker 1: see one side of it and not see another side
33:15
Speaker 1: of it. None of these things you can do in
33:16
Speaker 1: new one dimensional world. So try to imagine explaining to
33:20
Speaker 1: a one dimensional person what it means to turn a corner.
33:23
Speaker 1: They're like, what is a corner? What does that mean?
33:25
Speaker 1: What is that? What is that like? Now we are
33:27
Speaker 1: a one dimensional beings a long time, right, we think
33:30
Speaker 1: that there's one time to mention, So what does it
33:32
Speaker 1: mean to like turn a corner in two dimensional time?
33:36
Speaker 1: Honestly my brain struggles with the concept. Well, I'm not sure.
33:39
Speaker 1: We need to kind of go back to these analogies,
33:41
Speaker 1: Like I think just having like a left wrist watch
33:44
Speaker 1: and a right wrist watch might be a good way
33:46
Speaker 1: to kind of illustrate it, right, Like, if both both
33:48
Speaker 1: my watches are ticking along, that means I'm moving in
33:51
Speaker 1: both time directions at the same time. But if I
33:53
Speaker 1: suddenly see one watch freeze in time but the other
33:56
Speaker 1: one keep going, that means that I'm right now then
33:59
Speaker 1: moving through one dimension of time but not the other exactly.
34:03
Speaker 1: And if we're gonna have two dimensions of time, remember
34:05
Speaker 1: the role that time plays in physics. It allows things
34:08
Speaker 1: to change. You know, think about a basic equation F
34:11
Speaker 1: equals m A has like velocities in it. That's the
34:14
Speaker 1: motion of something with respect to time. Now imagine that
34:17
Speaker 1: there's two times in that equation. So those equations are
34:20
Speaker 1: now telling you like how things would evolve if you
34:23
Speaker 1: move forward in one time, or how they would evolve
34:25
Speaker 1: you move forward in the other time. And maybe they're different, right,
34:28
Speaker 1: Maybe flowing in time one is different than flowing in
34:31
Speaker 1: time too. And then the question is like, how does
34:33
Speaker 1: the universe flow along this plane? Is it a point
34:37
Speaker 1: meandering through this plane in time? Somehow is it moving
34:40
Speaker 1: just along one time access is it moving along both
34:43
Speaker 1: or is it somehow like a line sweeping across this
34:46
Speaker 1: plane right, like somehow the entire universe would be I
34:50
Speaker 1: guess moving through both time dimensions at the same time.
34:53
Speaker 1: I think the question is like, if my left watch
34:55
Speaker 1: is frozen and I'm moving through time on my right
34:58
Speaker 1: hand watch, I mean, and moving in time in the
35:01
Speaker 1: second dimension. But let's say you're staying in the first dimension, Like,
35:05
Speaker 1: can we even interact? Like, if we're different coordinates in time,
35:09
Speaker 1: can you and I still talk even if our left
35:11
Speaker 1: watches are synchronized, if our right watches are not synchronized,
35:14
Speaker 1: does that mean we're like in totally different time points. Well,
35:17
Speaker 1: in our universe, you certainly can interact if you're different
35:20
Speaker 1: locations in space and different locations in time. You know,
35:23
Speaker 1: I can send a message to the future. I can
35:25
Speaker 1: just write something on the wall and somebody later can
35:27
Speaker 1: come read it. I can receive messages from the past,
35:30
Speaker 1: you know, coming in later and looking at that wall.
35:33
Speaker 1: So you can definitely can communicate. The question of whether
35:36
Speaker 1: you can interact if you're different points in two D
35:38
Speaker 1: time depends specifically on the physics of that universe. How
35:42
Speaker 1: do things flow through these two dimensions of time? And
35:46
Speaker 1: actually becomes quite mathematically complicated. People have studied can you
35:50
Speaker 1: build laws of physics that have two dimensions in time
35:53
Speaker 1: that makes sense of this? You know, you have a
35:55
Speaker 1: specific thing that's happening, you know that now coming now
35:58
Speaker 1: for two dimensions and now and then can you predict
36:02
Speaker 1: what's going to happen tomorrow comming now versus now, comma
36:06
Speaker 1: tomorrow versus tomorrow comma tomorrow, Like, is the physics actually
36:10
Speaker 1: determined because in our universe we have one dimension of time.
36:14
Speaker 1: Physics we think about it as deterministic, you know, but
36:16
Speaker 1: quantum mechanics aside for a moment, we think that if
36:19
Speaker 1: you have a certain situation, we have laws of physics
36:22
Speaker 1: that tell you what the future will hold. Does that
36:24
Speaker 1: also work if you have two dimensions of time? Which
36:27
Speaker 1: I think is sort of what you're asking, you know,
36:30
Speaker 1: what are the rules about communicating across time? And people
36:32
Speaker 1: have actually studied this. They've tried to build laws of
36:35
Speaker 1: physics that allow for two dimensions of time, and you
36:38
Speaker 1: run into a lot of trouble. Actually, there's lots of
36:40
Speaker 1: cases where it just doesn't work. Where the universe like
36:43
Speaker 1: can't be self consistent. Wait, wait, what do you mean
36:46
Speaker 1: like something about our equations? Right now? Tell us you
36:48
Speaker 1: can't have more than one dimension of time. Most of
36:50
Speaker 1: physics is something we call an initial condition problem. We
36:53
Speaker 1: specify the universe now and then you run it forward
36:56
Speaker 1: in time. Right, So imagine a bunch of ping pong
36:59
Speaker 1: balls on the table. You know their position, you know
37:01
Speaker 1: their velocity, you can tell exactly where they're going to go,
37:04
Speaker 1: and putting quantum mechanics aside for the moment. But what
37:07
Speaker 1: if you have two dimensions of time? That means you
37:09
Speaker 1: need two sets of initial conditions, right, you need to
37:12
Speaker 1: know what happened at time equals zero along time one
37:15
Speaker 1: access and a long time to access. So instead of
37:18
Speaker 1: like having just a point as initial conditions, now you
37:21
Speaker 1: have this like line of initial conditions, and some of
37:24
Speaker 1: those things are inconsistent, right, Like, you can't always find solutions.
37:28
Speaker 1: Some sets of initial conditions just lead to nonsense. Is
37:31
Speaker 1: like no way to solve the wave equation to be
37:34
Speaker 1: consistent with both sets of initial conditions. And you know
37:37
Speaker 1: this happens a lot in physics where you just can't
37:39
Speaker 1: find solutions. You know where you've come up with some
37:41
Speaker 1: system that just like violates Maxwell's equations, and so you
37:45
Speaker 1: don't get a solution where you can figure out, like
37:47
Speaker 1: what is the electric field in the magnetic field in
37:49
Speaker 1: that condition. So if you have two sets of conditions
37:51
Speaker 1: in time, they can contradict each other and lead to inconsistencies. Right.
37:55
Speaker 1: I think what you're saying is that you know, the
37:57
Speaker 1: laws of physics, the way that we formulated with the
38:00
Speaker 1: way we've come up with them, are sort of there
38:02
Speaker 1: to predict what's going to happen in the future. Like
38:04
Speaker 1: I give you a certain amount of time, how is
38:06
Speaker 1: my position in space going to change? And so maybe
38:09
Speaker 1: you could have a contradiction where like if I put
38:11
Speaker 1: in this time, it tells me that I'm over here,
38:13
Speaker 1: but if I put in this other time, it tells
38:15
Speaker 1: me that I'm over there, and I can't be in
38:17
Speaker 1: both places at the same time. Right, I mean, I've tried,
38:19
Speaker 1: but it usually it doesn't work. Yeah, And so people
38:22
Speaker 1: have tried to fix this. They said, well, let's not
38:25
Speaker 1: just use the laws of our universe and assume that
38:27
Speaker 1: physics works the same way in two D time, and
38:30
Speaker 1: ask well, what would we have to add? What extra
38:33
Speaker 1: rules do we need to tack onto the universe to
38:36
Speaker 1: make it work in two dimensional time. So it gets
38:39
Speaker 1: a little hairy mathematical. But people have found some ways
38:41
Speaker 1: to add constraints and say, well, you can't just have
38:44
Speaker 1: any initial condition you want. You have some rules about
38:46
Speaker 1: what initial conditions are allowed, so that you get solutions
38:50
Speaker 1: that work for both times, So you can run one
38:53
Speaker 1: clock forward or the other clock forward or both and
38:56
Speaker 1: have consistent predictions. That makes sense, So it is possible.
38:59
Speaker 1: Then it's possible if you change fundamentally the way physics
39:02
Speaker 1: works in an interesting way. But what that means is, like,
39:05
Speaker 1: you know, maybe the universe is different from the way
39:08
Speaker 1: we thought. If there are two dimensions of time, it
39:10
Speaker 1: means that there's this new sort of rule about how
39:14
Speaker 1: time works that doesn't apply for one dimensional time, and
39:17
Speaker 1: that's pretty awesome. We'll definitely make making appointments a lot harder.
39:20
Speaker 1: I mean, it's hard enough to coordinate meetings with the
39:24
Speaker 1: one timeline, imagine having to do it in a whole
39:27
Speaker 1: space of time. All right, Well, let's get into what
39:29
Speaker 1: other mathematical problems this idea raises and introduces into physics,
39:34
Speaker 1: and also whether it allows time travel, because maybe it
39:37
Speaker 1: does So let's get into that. But first let's take
39:39
Speaker 1: another quick break where we're talking about dimensions of time
39:56
Speaker 1: and whether there are more than one dimensions of our
40:00
Speaker 1: our time travels. I guess, are we actually moving in
40:03
Speaker 1: multiple time dimensions at the same time. It would be
40:05
Speaker 1: really awesome, man, what a discovery to make to reveal
40:09
Speaker 1: that the universe is so different from the way everybody
40:11
Speaker 1: has ever thought it was. That's like a real scientific fantasy.
40:15
Speaker 1: That's sort of like the fundamental level of discovery I
40:17
Speaker 1: would love to make. Maybe you already did, Daniel, you know,
40:20
Speaker 1: like in another time, already did technically, maybe I already
40:24
Speaker 1: did slash haven't yet? Yeah there you go. Know you
40:27
Speaker 1: did it, but you went back in time because you
40:29
Speaker 1: realized it was a bad idea. But maybe I'm just
40:32
Speaker 1: doomed to discover it over and over. Or maybe you
40:36
Speaker 1: did it in a in a pocket universe, you know,
40:38
Speaker 1: a time pocket, but then you came back to the
40:40
Speaker 1: same time and you had already forgotten. Yeah, maybe the
40:42
Speaker 1: Daniel that makes that dangerous discovery should be stuffed into
40:45
Speaker 1: one of those mirror universes they have like in Superman. Yeah,
40:48
Speaker 1: a little time out for physicists instead, of cryogenically freezing me,
40:53
Speaker 1: just stuffed me in an alternate universe. Nice because just
40:57
Speaker 1: lots of options for taking physicists out of commission or
41:01
Speaker 1: science fiction authors are also parents, and they think about
41:03
Speaker 1: time outs a lot. Well, let's keep talking about time
41:06
Speaker 1: and whether there are more dimensions of it. I guess
41:08
Speaker 1: that's a big question, Daniel. Would having more dimensions of
41:11
Speaker 1: time allow us to travel through time? Actually, I think
41:14
Speaker 1: it's really fun to think about this because one of
41:16
Speaker 1: my big complaints with time travel movies is that they're
41:20
Speaker 1: fundamentally nonsense, and their fundamentally nonsense in this really important
41:24
Speaker 1: way that I think a second dimension of time might solve. Right, So,
41:29
Speaker 1: most time travel movies have this idea of like a timeline.
41:33
Speaker 1: You know, things happen. You have one dimension of time.
41:36
Speaker 1: Things are flowing along the timeline, and you know, in
41:38
Speaker 1: our universe, the timeline is this idea, as you said earlier,
41:42
Speaker 1: that like things can change before you ate lunch and
41:44
Speaker 1: after you ate lunch. What's the difference. The difference is time.
41:47
Speaker 1: Time allows things to change. But now if you're taking
41:50
Speaker 1: a step out of that, you not on the timeline anymore,
41:53
Speaker 1: but you're looking at the timeline, and you can see
41:56
Speaker 1: that like the timeline itself doesn't change. You describe the history,
42:00
Speaker 1: you're the universe. It's like a certain thing happened at
42:02
Speaker 1: a certain time, and then a certain thing happened in
42:05
Speaker 1: later time, etcetera, etcetera. Happens in time travel movies is
42:08
Speaker 1: often that that timeline itself changes, right, Somebody goes off
42:13
Speaker 1: the timeline and loops back to a previous time and
42:16
Speaker 1: changes the timeline. And I complaint in those scenarios is
42:20
Speaker 1: always the same as that change requires time. There's a
42:24
Speaker 1: time before you made a change, in a time after
42:26
Speaker 1: you made a change. The same way, that's a time
42:27
Speaker 1: before you had lunch at a time after you had lunch.
42:30
Speaker 1: So if you're changing the timeline, then there's a version
42:33
Speaker 1: of the timeline before you changed it and after you
42:35
Speaker 1: changed it. But along what time to mension is that
42:39
Speaker 1: change happening? Right, The timeline itself can't change because change
42:45
Speaker 1: is only along the timeline. So that's my number one
42:47
Speaker 1: complaint with time travel movies. Maybe that gives you a
42:50
Speaker 1: hint as to how two D time could solve that.
42:54
Speaker 1: I get that also the sience. You have many complaints
42:56
Speaker 1: about science at least. But I will say though that
42:58
Speaker 1: I think, you know, people who write these movies and
43:00
Speaker 1: these shows have gotten pretty complicated, and you know, I
43:02
Speaker 1: think they do talk to physicists about these things. And
43:04
Speaker 1: if you know what it is like, for example, in
43:06
Speaker 1: the Avengers movie, they talk about they don't talk about
43:08
Speaker 1: timelines changing. They talk about timeline splitting or you know,
43:12
Speaker 1: like you generate a new timeline that splits off from
43:15
Speaker 1: the original time, which doesn't technically change it just you
43:18
Speaker 1: split off a new timeline, So they don't really talk
43:21
Speaker 1: about timeline it's changing. Yeah, I guess it depends. Are
43:24
Speaker 1: you thinking about splitting as a change, like the timeline
43:26
Speaker 1: was one timeline and then it's split into two timelines,
43:30
Speaker 1: because that would also be a form of change, or
43:32
Speaker 1: you could think of them as sort of like the
43:33
Speaker 1: Harry Potter version, where like it always has this weird
43:37
Speaker 1: structure where it like forks into multiple versions in some
43:40
Speaker 1: you know, double quantum universe thing. But still then people
43:43
Speaker 1: are moving from one timeline to the other. Doesn't that
43:46
Speaker 1: require some kind of like change to the timeline. Well,
43:49
Speaker 1: if you're just jumping between timelines, you don't need to change, right,
43:52
Speaker 1: you can just job I mean it's science fiction that
43:55
Speaker 1: you know in this do you take a fictional universe
43:59
Speaker 1: you could just take be changed between times and not
44:01
Speaker 1: how would change? Right? But I think what you're saying
44:03
Speaker 1: is the problem is that you can't change the timeline. Right.
44:06
Speaker 1: So like even though the Avengers went back in time
44:09
Speaker 1: and safe half of the universe, there's still a timeline
44:11
Speaker 1: a universe where the half of the people in the
44:14
Speaker 1: universe are still dead, right, So that doesn't help you much. Yeah,
44:17
Speaker 1: who's thinking about those people? Man? Like all those folks
44:21
Speaker 1: out there not able to buy tickets for future Marvel
44:23
Speaker 1: movies because they got snapped out of existence, right, Yeah,
44:27
Speaker 1: they lost out on a lot of revenue there. But
44:30
Speaker 1: I think what you're saying is that even though something
44:32
Speaker 1: maybe these writers didn't think about is that it's to
44:35
Speaker 1: change the timeline, like you said, would require time, right
44:38
Speaker 1: or some some sort of change. Yeah, I think about
44:41
Speaker 1: before you change the timeline, and after you change the timeline,
44:45
Speaker 1: you know along what time access is that happening? Well,
44:48
Speaker 1: the answer is maybe there's a second dimension of time.
44:52
Speaker 1: And in these movies like Back to the Future or whatever,
44:55
Speaker 1: you know, there seems to be this like narrative time. Right,
44:57
Speaker 1: you're watching the movie. Things are flowing through the movie,
45:00
Speaker 1: and you're watching the timeline change. That's implicitly another dimension
45:05
Speaker 1: of time, right, And so in this universe, maybe if
45:08
Speaker 1: you have multiple time dimensions, then they're not exactly equivalent
45:12
Speaker 1: the way we're talking about a moment ago we have
45:14
Speaker 1: like some plane where you have two coordinates in time
45:17
Speaker 1: and they're fundamentally equivalent. In it's a metric in some way.
45:19
Speaker 1: Maybe there are two dimensions of time, but they're different.
45:21
Speaker 1: One like runs along the timeline and the other one
45:24
Speaker 1: allows the timeline itself to change. Right. It's sort of
45:27
Speaker 1: like like we talked about before, like if you have
45:29
Speaker 1: two watches, one on your right risk and one in
45:31
Speaker 1: your left wrist, Like you know right now my left
45:34
Speaker 1: wrist watch is synchronize with the whole universe. Right, But
45:37
Speaker 1: maybe I can sort of step out of time, use
45:40
Speaker 1: some of the time and my ride watch to maybe
45:42
Speaker 1: go back to a different point, and now I'm in
45:44
Speaker 1: a the same universe, but shifted in time in another dimension,
45:48
Speaker 1: in an in another direction. Right, Like you can use
45:52
Speaker 1: the story time or time too or whatever to go
45:55
Speaker 1: back and change the original time, and that would allow
45:58
Speaker 1: the timeline to have a previous state in a later
46:01
Speaker 1: state without having some sort of internal conflict. It's like
46:04
Speaker 1: when it was because now you have this other dimensions,
46:07
Speaker 1: additional freedom now right, right, But that's basically the same
46:11
Speaker 1: as splitting the timeline. Right, It's like the other universe
46:13
Speaker 1: where the half of the people got snapped out of
46:15
Speaker 1: existence is still there, Like it's still that's still in
46:19
Speaker 1: the plane of time. But now I'm in a better
46:21
Speaker 1: universe where I actually got to change things. Well, it's
46:23
Speaker 1: still there in the past. Yeah, but you've gone back
46:26
Speaker 1: and you change the timeline. So the timeline according to
46:29
Speaker 1: time too, is no longer the time in which all
46:31
Speaker 1: those people suffer. So yeah, in the past of this universe,
46:35
Speaker 1: there is a timeline in which those people would have suffered,
46:38
Speaker 1: but in the future of this universe they don't. So
46:42
Speaker 1: it's you know, you've solved the problem in a different way,
46:44
Speaker 1: I think, right, But I think it sort of goes
46:46
Speaker 1: back to the question I had before, Like if my
46:48
Speaker 1: left watch and your left watch are synchronized, but my
46:50
Speaker 1: ride watch is a different time than your right watch,
46:53
Speaker 1: are we still able to have a regular conversation or
46:56
Speaker 1: it might even able to shake your hand. Yeah, it
46:58
Speaker 1: just depends on the universe are in and what rules
47:01
Speaker 1: it follows with respect to time one and time too.
47:04
Speaker 1: If those are very very similar, and physics respects time
47:07
Speaker 1: one and time two in the same way, then yeah,
47:09
Speaker 1: we can definitely interact. That depends a little bit on
47:11
Speaker 1: the complicated special relativity of three plus two space time.
47:15
Speaker 1: But if it's different, If time one and time two
47:17
Speaker 1: are fundamentally different from each other, and the rules for
47:20
Speaker 1: how time two flows aren't different from time one, then
47:23
Speaker 1: all bets are off. I read a really fun novel
47:26
Speaker 1: by one of my favorite authors, Greg Egan, who's a
47:28
Speaker 1: really creative thinker about how the universe could be different,
47:32
Speaker 1: and it's written great books like Diaspora, which I totally recommend.
47:35
Speaker 1: And he wrote this book called dichro Knots about a
47:38
Speaker 1: universe that has two spatial dimensions and two time dimensions,
47:43
Speaker 1: so like really takes you through like what it would
47:45
Speaker 1: be like to be a dichro knot a person or
47:48
Speaker 1: a thing living in a universe with two dimensions of time.
47:52
Speaker 1: And he's like worked out the whole physics of it
47:54
Speaker 1: in his in his universe and at least all these
47:56
Speaker 1: really strange consequences like sometimes water flows up hill instead
48:00
Speaker 1: of downhill. It's really amazing cool. Yeah, check it out
48:03
Speaker 1: that novel. And I have to say, I have tasted chronos,
48:06
Speaker 1: so those are pretty pretty tasty. But have you had
48:09
Speaker 1: two of them at the same time. I don't know
48:10
Speaker 1: about dicronots. I mean I get to have two chronuts.
48:13
Speaker 1: It's a chronic chronut sandwich. Yeah. I like these two dimensions,
48:17
Speaker 1: all right, But maybe let's get back to physics here.
48:19
Speaker 1: And so I think you're telling me that there's nothing
48:22
Speaker 1: in our current equations or our knowledge of the universe
48:26
Speaker 1: that says that you can't have more the dimensions of time,
48:29
Speaker 1: Like we could totally have more than one dimension of time.
48:32
Speaker 1: It could be that our universe has more than one
48:34
Speaker 1: dimension of time. On either hand, there are no hints.
48:37
Speaker 1: It's not like there's any evidence anywhere that requires it.
48:40
Speaker 1: You know, in some cases there are things that would
48:42
Speaker 1: be better or explained if we had extra dimensions of space,
48:45
Speaker 1: like gravity and large extra dimension theories and all that
48:47
Speaker 1: kind of stuff. There's not even anything about that for time.
48:50
Speaker 1: It's like maybe some versions of string theory that work
48:53
Speaker 1: better with two D time, but it's really the speculation
48:56
Speaker 1: on speculation, but it is possible. Yes, it's possible that
48:59
Speaker 1: they're our two dimensions of time, and that we just
49:02
Speaker 1: haven't noticed the second dimension yet. We don't understand how
49:05
Speaker 1: to experience it. We're like those two D people living
49:08
Speaker 1: in a three D universe, not able to look off
49:11
Speaker 1: the plane of our existence and understand this other way
49:14
Speaker 1: of moving we're thinking, right, I guess it could be
49:17
Speaker 1: that we're you know, it's there, but we just haven't
49:19
Speaker 1: seen it, or it could be that we are moving
49:21
Speaker 1: through it. It's just that the way our thinking process works,
49:24
Speaker 1: or the way we've somehow formulated our understanding of the universe, doesn't,
49:29
Speaker 1: you know, let us see it, or maybe we see
49:31
Speaker 1: it all much together somehow exactly the way that relativity
49:34
Speaker 1: has been in effect well before we discovered it, and
49:37
Speaker 1: it was changing the way of the universe worked. We
49:39
Speaker 1: just didn't notice it because the effects were very very
49:41
Speaker 1: small because of the way that we lived, the speeds
49:44
Speaker 1: and the size of our lives, and so it could
49:47
Speaker 1: be that the universe has two dimensions of time. We
49:50
Speaker 1: just haven't really revealed it well enough yet because of
49:52
Speaker 1: the particular way that we are living our lives. Interesting Alright,
49:58
Speaker 1: so the next time I'm late to a meeting, I
49:59
Speaker 1: can just day I was, I was on time and
50:01
Speaker 1: the other time, can I say that? Can I these
50:04
Speaker 1: physics as an excuse. You don't even need excuses anymore, man,
50:08
Speaker 1: People just expect it by now. There you go, I've
50:11
Speaker 1: recalibrated the universe to my time. That I it sounds
50:14
Speaker 1: like I want Daniel. Yeah, I think you really are
50:16
Speaker 1: the center of the universe. But I think it's a
50:18
Speaker 1: fun exercise. You know, for those of you thinking like
50:20
Speaker 1: this is ridiculous, it's important to try to push the boundaries.
50:24
Speaker 1: And it might not be the time has two dimensions,
50:26
Speaker 1: or that any of the theories we talked about today
50:28
Speaker 1: are accurate. But it's an exercise that maybe stumbles along
50:31
Speaker 1: another crazy idea or forces us to invent a new
50:34
Speaker 1: kind of mathematics which stumulates another idea. This sort of
50:37
Speaker 1: like creative theoretical exploration is really really vital to solving
50:42
Speaker 1: the big questions about the universe. Yeah, I mean, that's
50:44
Speaker 1: how we discovered a lot of the amazing things we
50:47
Speaker 1: have discovered, right like what if the universe is quantized,
50:50
Speaker 1: or what if time and space are malleable? That's the
50:52
Speaker 1: kind of crazy question you have to ask to really
50:55
Speaker 1: find the truth. Yeah, you got to spend some time
50:57
Speaker 1: thinking crazy. All right, Well, we hope you had a
51:00
Speaker 1: good time listening to this discussion about time according to
51:03
Speaker 1: your left watch or your right watch. I think it's
51:05
Speaker 1: time to go see you next time. Thanks for listening,
51:16
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
51:18
Speaker 1: a production of I Heart Radio. For more podcast from
51:22
Speaker 1: my heart Radio, visit the i heart Radio app, Apple Podcasts,
51:26
Speaker 1: or wherever you listen to your favorite shows. Yea,