WEBVTT - What's a Tesseract? 0:00:08.520 --> 0:00:11.320 Hey, Jorge, if you could have just one of the 0:00:11.400 --> 0:00:15.440 Infinity Stones from the Avengers, which one would you pick? Oh? Man, 0:00:15.880 --> 0:00:19.279 there's five good choices, but I think the obvious one 0:00:19.560 --> 0:00:21.760 is the Time Stone. Oh yeah, why is that too? 0:00:21.800 --> 0:00:26.440 You'd have more time to nap or avoid missing deadlines then, 0:00:26.520 --> 0:00:28.680 and you could also go back in time and get 0:00:28.720 --> 0:00:33.520 the other stones. Very clever. It's like wishing for more wishes. Well, 0:00:33.920 --> 0:00:37.800 I would probably take the reality Stone. You're not happy 0:00:37.840 --> 0:00:40.760 with our current reality now. I'm feeling kind of tied 0:00:40.800 --> 0:00:43.160 down by all these physical laws. I want to break 0:00:43.159 --> 0:00:45.519 one or two of them. And that doesn't make me 0:00:45.600 --> 0:00:48.839 feel comfortable about giving billions of dollars to physicists. You 0:00:48.840 --> 0:00:51.360 don't want to watch the TV show called Physicists Gone 0:00:51.360 --> 0:01:09.600 Wild as long as nobody takes their shirts off. I 0:01:09.600 --> 0:01:12.720 am more handmade cartoonists and the creator of PhD comics. Hi, 0:01:12.880 --> 0:01:16.600 I'm Daniel. I'm a particle physicist, and I go wild 0:01:16.880 --> 0:01:20.319 for crazy particle physics discoveries. Oh nice, what does that mean? 0:01:20.360 --> 0:01:22.960 You let your hair grow out, you sleep out in 0:01:23.080 --> 0:01:25.720 nature or at the collider. Well, you know, I've only 0:01:25.800 --> 0:01:29.200 been in this field for twentysomething years, and in those 0:01:29.240 --> 0:01:33.039 two plus decades, we've basically only had one discovery, which 0:01:33.120 --> 0:01:36.199 was the Higgs boson. So that's really the only place 0:01:36.280 --> 0:01:38.399 I can refer to. And Yeah, we had a lot 0:01:38.400 --> 0:01:40.600 of parties. We drank a lot of nice champagne. We 0:01:40.640 --> 0:01:44.360 had a lot of French cheese. It was wow. Nobody 0:01:44.400 --> 0:01:48.680 picked their shirts off now that I can remember, well, 0:01:48.680 --> 0:01:51.440 Welcome to our podcast, Daniel and Jorge Explain the Universe, 0:01:51.520 --> 0:01:54.400 a production of I Heart Radio in which we celebrate 0:01:54.480 --> 0:01:57.880 all the crazy, wacky, wild stuff about the universe. The 0:01:58.000 --> 0:02:00.520 things that we don't understand going on in the hearts 0:02:00.520 --> 0:02:02.680 of black holes, to the things we think we might 0:02:02.760 --> 0:02:06.280 be grappling with on the quantum mechanical scale, Everything that 0:02:06.360 --> 0:02:09.200 you want to know about the universe, everything you didn't 0:02:09.240 --> 0:02:11.200 know that you wanted to know about the universe. We 0:02:11.280 --> 0:02:13.320 talk about all of it, and we explain all of 0:02:13.360 --> 0:02:16.440 it to you because it is a pretty fascinating universe. 0:02:16.480 --> 0:02:18.440 There's a lot going on out there and a lot 0:02:18.480 --> 0:02:21.200 for us to discover and also a lot for us 0:02:21.200 --> 0:02:24.480 to imagine happening. Absolutely, and it's fun to think about 0:02:24.480 --> 0:02:27.079 how the universe might work in different ways. Does it 0:02:27.200 --> 0:02:29.240 work the way we expect or is life here on 0:02:29.280 --> 0:02:32.000 Earth kind of unusual and weird, and if we could 0:02:32.000 --> 0:02:34.240 go to other places in the universe, we might see 0:02:34.280 --> 0:02:37.600 things working very differently and learned some deeper truth about 0:02:37.639 --> 0:02:40.760 the nature of the universe and reality. Yeah, unfortunately we 0:02:40.840 --> 0:02:43.480 have here in our human species, in our human society, 0:02:43.520 --> 0:02:47.160 we have awesome writers and artists who can imagine some 0:02:47.200 --> 0:02:49.520 of these things for us, and sometimes that spills over 0:02:49.600 --> 0:02:54.680 into reality. That's right. Sometimes art and literature and science 0:02:54.800 --> 0:02:58.239 actually connect and we can explore these fun concepts about 0:02:58.280 --> 0:03:01.040 the basic nature of space and time and how our 0:03:01.120 --> 0:03:05.560 universe works in lots of different fund ways, including superhero movies. Yeah, 0:03:05.760 --> 0:03:08.000 you know, I feel like something there are topics in 0:03:08.040 --> 0:03:12.040 these science fiction or fantasy or superhero movies that sort 0:03:12.040 --> 0:03:14.600 of feel like they could be real, but you're not sure. 0:03:14.840 --> 0:03:18.200 At least it looks pretty real in the movie. It does. 0:03:18.240 --> 0:03:20.480 And I know that Martin Scorsese is not a fan 0:03:20.560 --> 0:03:23.080 of superhero movies, but I like that they bring up 0:03:23.080 --> 0:03:25.160 a lot of these scientific elements. You know, I never 0:03:25.160 --> 0:03:28.320 saw Martin Scorsese movie bring up fundamental questions of the 0:03:28.400 --> 0:03:30.960 nature of space and time. There are some place concepts 0:03:31.000 --> 0:03:34.240 in fantasy and science fiction movies and superhero movies that 0:03:34.320 --> 0:03:37.880 you know, sound very techy and science and you sort 0:03:37.880 --> 0:03:41.560 of wonder if they are actually real things exactly in 0:03:41.560 --> 0:03:44.240 our goal on this podcast is not just to explain 0:03:44.320 --> 0:03:47.520 what scientists are thinking, but to dig deep into what 0:03:47.720 --> 0:03:50.880 you are thinking, to answer your questions about the nature 0:03:50.920 --> 0:03:53.520 of the universe, and explain to you things you might 0:03:53.520 --> 0:03:56.000 have heard about and wanted broken down. So to be 0:03:56.120 --> 0:04:03.480 on the podcast, we'll be asking the question what is 0:04:03.920 --> 0:04:06.800 a test iract now, Daniel, is it test irat or 0:04:07.000 --> 0:04:12.600 test rat or I think it's test i act? I said, 0:04:12.600 --> 0:04:19.159 you got you gotta say with some drama, some enthusiasm. Yeah. 0:04:19.320 --> 0:04:21.640 This is a concept that comes up in a couple 0:04:21.720 --> 0:04:24.599 of interesting places like the Avengers movies. It was one 0:04:24.640 --> 0:04:26.640 of the things that they were fighting about and trying 0:04:26.680 --> 0:04:30.080 to control, and also in the Wrinkle in Time Blox 0:04:30.480 --> 0:04:33.400 and wasn't it also in that movie Interstellar? Everything was 0:04:33.440 --> 0:04:35.800 an interstellar Man that was just like a garbage can 0:04:35.880 --> 0:04:40.600 of all the ideas that everybody had. Man, I was 0:04:40.720 --> 0:04:45.279 a pretty negative assessment there. Well, you know, time is 0:04:45.360 --> 0:04:47.520 love and you can move through the fifth dimension if 0:04:47.520 --> 0:04:49.360 you believe in love. Like, I don't even know what 0:04:49.400 --> 0:04:52.039 that was Obviously you're not paying attention, Daniel. Love is 0:04:52.080 --> 0:04:55.920 the fifth dimension? I love the fifth dimension? Is that 0:04:55.960 --> 0:05:00.720 what that means? And I think you to watch it again? 0:05:00.720 --> 0:05:02.440 And you know, I think I'm not smart enough to 0:05:02.480 --> 0:05:05.279 understand that movie. That's really the problem. That's Christopher Nolan 0:05:05.360 --> 0:05:08.120 movie for you. You need like a PhD or something. 0:05:08.920 --> 0:05:12.279 I need like seven peachd's like Brince Banner. M there 0:05:12.320 --> 0:05:14.960 you go back to the Avengers, all right, Yeah, the 0:05:15.000 --> 0:05:17.720 test arrect shows up in the Avengers movies. And so 0:05:17.800 --> 0:05:20.400 this actually came from one of our listeners. They posted 0:05:20.400 --> 0:05:22.960 a question to us. That's right. This is a concept 0:05:23.000 --> 0:05:24.960 that one of our listeners had heard all about and 0:05:25.040 --> 0:05:28.200 wanted broken down. So if you have a question you 0:05:28.360 --> 0:05:31.720 hear about in science that you'd like explained, please send 0:05:31.720 --> 0:05:33.479 it to us. We'd love to hear from you and 0:05:33.560 --> 0:05:36.920 love to help you understand these concepts. So here's the 0:05:37.000 --> 0:05:41.000 question from Zoe from Vietnam. Hi, Daniel, and hell, hey, 0:05:41.120 --> 0:05:43.960 I'm a big fan of your podcast. Um. I used 0:05:44.000 --> 0:05:47.760 to dislike physics in high school, but your podcast has 0:05:47.800 --> 0:05:51.359 now made me realize how funny and interesting physics can be. 0:05:52.240 --> 0:05:55.680 I've recently been introduced to the concept of a test arrect, 0:05:56.200 --> 0:05:58.080 and I was just wondering if you could make a 0:05:58.160 --> 0:06:01.719 podcast episode about how a test ract describes a four 0:06:01.760 --> 0:06:06.000 dimensional space, is the fourth dimension time and does the 0:06:06.120 --> 0:06:09.120 testrect relate to the concept of space time? Thank you? 0:06:09.520 --> 0:06:12.320 All right? Thank you? Zoe? When if she's seen the 0:06:12.360 --> 0:06:15.799 Avengers movies. They made it out there to Vietnam, didn't 0:06:15.800 --> 0:06:19.560 they They're everywhere. Yeah, it's an interesting question, and it's 0:06:19.640 --> 0:06:21.480 one that we were wondering. How many people out there 0:06:21.520 --> 0:06:23.680 had an idea about what this could be exactly. So 0:06:23.800 --> 0:06:27.320 we asked our other listeners questions from Zoe the listener, 0:06:27.520 --> 0:06:30.279 and so basically we're not even needed anymore. The listeners 0:06:30.279 --> 0:06:33.240 are asking questions and answering questions. Yeah, we're just here 0:06:33.279 --> 0:06:37.240 to provide the bad jokes and the Wikipedia reading no, 0:06:37.480 --> 0:06:39.919 and to make everybody realize that physics is awesome. That 0:06:39.960 --> 0:06:42.120 was my favorite moment in her question, that we have 0:06:42.440 --> 0:06:45.320 made physics fun for her awesome. So Daniel went out 0:06:45.320 --> 0:06:48.000 there and asked people and here's what they had to say. 0:06:48.279 --> 0:06:51.400 I think the test wractor is the four dimensional cube, right, 0:06:51.680 --> 0:06:53.880 have you seen that? Like my mind has the animation 0:06:53.960 --> 0:06:56.640 like the cube turning itself inside out. It's supposed to 0:06:56.640 --> 0:06:58.320 be like a visual aid to help you think about 0:06:58.320 --> 0:07:04.760 the fourth dimension. Never saw tessellation. Tessellate could be could 0:07:04.760 --> 0:07:07.599 be same route word. Yeah, I've heard of that before 0:07:07.760 --> 0:07:12.920 as being a fourth dimensional more model of a cube 0:07:12.960 --> 0:07:16.280 which acts in the three dimensions, And I've also seen 0:07:17.240 --> 0:07:22.920 an animation which shows how it behaves. But it's a 0:07:22.960 --> 0:07:27.040 little bit over my head how that works a fold 0:07:27.280 --> 0:07:31.400 in space, and apparently to make one you just have 0:07:31.520 --> 0:07:39.040 to think really hard about it. Testarunt is something super cube, 0:07:39.360 --> 0:07:44.200 like four dimensional cube, but I know it's something more 0:07:44.240 --> 0:07:47.920 than that. I don't know more. I don't know what 0:07:48.000 --> 0:07:50.960 test rings are in physics. When I remember the Avengers movie, 0:07:51.120 --> 0:07:53.840 they were like blue cubes that had like a lot 0:07:53.840 --> 0:07:56.200 of energy, So it might be something relating to energy. 0:07:56.960 --> 0:07:59.360 I remember hearing about it in the movies. A lot 0:07:59.440 --> 0:08:02.240 I don't remember, but I think it's something to do 0:08:02.320 --> 0:08:09.040 with like either time travel or bending space. All right, See, 0:08:09.040 --> 0:08:11.800 a lot of people had heard about it from the movies, Yeah, exactly, 0:08:11.840 --> 0:08:14.400 the Avengers. That's definitely made this idea, or at least 0:08:14.400 --> 0:08:18.200 this word popular, And according to them, it's a blue 0:08:18.240 --> 0:08:22.480 cube with a lot of energy. Yeah, a lot of 0:08:22.560 --> 0:08:26.440 power in it, somehow mysterious power. Why is mysterious stuff 0:08:26.440 --> 0:08:28.560 in the movie is always glowing blue? You know, it's 0:08:28.600 --> 0:08:31.679 like blue some special thing for our brains. It means 0:08:31.720 --> 0:08:35.960 like weird and unnatural. M Sometimes it's purple. Yeah, the 0:08:36.160 --> 0:08:39.720 Infinity Stones all had different colors. They're all mysterious and powerful. 0:08:39.880 --> 0:08:41.880 That's true. And you know, it turns out the Infinity 0:08:41.920 --> 0:08:44.120 Stones all used to have different colors like in the 0:08:44.120 --> 0:08:46.719 original comic books. And there's like a reboot, but they 0:08:46.720 --> 0:08:50.160 swapped all the colors. No kidding, Yeah, exactly. Maybe they 0:08:50.240 --> 0:08:53.959 used the Reality Stone, dude, with the colors. I come 0:08:54.000 --> 0:08:57.240 from an alternate universe where the Reality Stone was always purple. 0:08:58.240 --> 0:09:03.120 What It's all going towards the multiverse apparently. So that's alright, 0:09:03.120 --> 0:09:05.640 So break it down for us. What is a test react? Tests? 0:09:05.640 --> 0:09:10.120 React a super fun concept. It starts in geometry, where 0:09:10.120 --> 0:09:15.199 it's basically the fourth dimensional extrapolation of what a cube 0:09:15.280 --> 0:09:17.920 would be in three D. But it really does have 0:09:18.120 --> 0:09:21.640 deep connections to like the nature of space and space time, 0:09:21.720 --> 0:09:24.520 and then of course it does appear in science fiction. 0:09:24.679 --> 0:09:26.720 But at the root of it, it really is a 0:09:26.880 --> 0:09:31.000 geometrical object. Take a cube, which is a three D object, 0:09:31.200 --> 0:09:33.760 and try to imagine with the four D version of 0:09:33.800 --> 0:09:37.240 that would be that's a tests react M. You mean, 0:09:37.280 --> 0:09:40.720 like you know, length with depth would be three dimensions, 0:09:41.280 --> 0:09:44.000 And like what if you added a fourth one? Yeah, exactly. 0:09:44.080 --> 0:09:45.719 You start with a point to which is zero D. 0:09:46.080 --> 0:09:48.560 You make a line which is one D. Then you 0:09:48.600 --> 0:09:50.800 add the second dimension. You get a plane. You had 0:09:50.840 --> 0:09:53.480 a third dimension, you get a cube. A tessaract is 0:09:53.520 --> 0:09:56.000 what happens if you add a fourth dimension? M M. 0:09:56.280 --> 0:09:58.280 I see. And it has to be like a dimension 0:09:58.280 --> 0:10:01.800 in space, like could it be like a density? Could 0:10:01.800 --> 0:10:05.640 that be something or I don't know color. That's a 0:10:05.640 --> 0:10:08.320 cool idea, you know. Mathematically it doesn't have to be 0:10:08.320 --> 0:10:11.720 connected to anything physical in geometry. These are just you know, 0:10:11.840 --> 0:10:15.199 points in some arbitrary space. But by space they don't 0:10:15.200 --> 0:10:18.360 necessarily mean like physical space. It could be space, it 0:10:18.360 --> 0:10:21.120 could be time, it could be anything else really, and 0:10:21.200 --> 0:10:24.400 so mathematically it's just sort of like an abstract concept. 0:10:24.440 --> 0:10:27.679 It's like a relationship between points. It's the definition of 0:10:27.800 --> 0:10:30.640 like the number of ways you can move around in 0:10:30.720 --> 0:10:34.320 that space. I see. So, but mostly people think of 0:10:34.360 --> 0:10:37.240 it as sort of like something you can move around in, right, 0:10:37.360 --> 0:10:40.320 like you can't. It's hard to move around color or 0:10:40.520 --> 0:10:43.079 or density. You can map it dimension anything. Yeah, you 0:10:43.120 --> 0:10:46.920 could map it to color, you could map into density. Really, 0:10:46.960 --> 0:10:49.960 you take this abstract concept of a dimension and map 0:10:50.000 --> 0:10:53.160 into something physical basically anything you Like, The question is 0:10:53.360 --> 0:10:56.160 does that really mean anything? Like is there anything in 0:10:56.200 --> 0:10:59.400 our universe which really respects that as a dimension or 0:10:59.640 --> 0:11:02.000 refle lets that as a dimension. That's why, for example, 0:11:02.160 --> 0:11:04.640 and we'll dig into this later, why we think space 0:11:04.679 --> 0:11:07.320 and time might fit together into four dimensions because there 0:11:07.360 --> 0:11:10.360 are real physical things about our universe that reflect and 0:11:10.400 --> 0:11:13.040 respect that dimensionality. But you can make up your own 0:11:13.080 --> 0:11:17.000 dimensions doesn't necessarily mean anything. M So it has more 0:11:17.040 --> 0:11:19.760 to do with like a coordinate system, right, Like if 0:11:19.760 --> 0:11:21.840 you have a coordinate system like x, y and z, 0:11:22.040 --> 0:11:24.400 what happens if you add another one like double a 0:11:24.559 --> 0:11:27.800 or something? Yeah, or you go backwards you had W right, 0:11:27.880 --> 0:11:30.920 So like W X, y and z. And this is 0:11:30.960 --> 0:11:33.800 tricky to think about because we're used to thinking in 0:11:33.840 --> 0:11:35.720 three D, because they're you still living in three D. 0:11:36.000 --> 0:11:38.280 So you might be trying to imagine in your head, like, well, 0:11:38.320 --> 0:11:41.120 what is a four dimensional version of a cube? Look 0:11:41.200 --> 0:11:44.080 like it's not hard to imagine a point or a line, 0:11:44.480 --> 0:11:47.280 or a plane or even a cube. How do you 0:11:47.320 --> 0:11:50.560 like play the mental game of imagining a four D cube? 0:11:50.600 --> 0:11:52.880 What does it tests aract, look like other than like 0:11:52.920 --> 0:11:55.400 a blue glowing cube on the screen at the movie theater. 0:11:55.840 --> 0:11:58.560 I see, So it's a geometric shape basically, but it's 0:11:58.600 --> 0:12:01.920 a geometric shape in four dimensions, exactly in four dimensions, 0:12:02.120 --> 0:12:04.960 and we can play games trying to imagine what it 0:12:05.040 --> 0:12:07.960 might look like. Obviously, we can't like build something in 0:12:08.000 --> 0:12:10.120 four dimensional space because we think we live in three 0:12:10.120 --> 0:12:13.199 dimensional space, But that doesn't mean you can't like play 0:12:13.240 --> 0:12:15.360 some games to help yourself understand it. Like, you know, 0:12:15.480 --> 0:12:18.720 you can look at the drawing of a cube. Drawing 0:12:18.840 --> 0:12:20.800 is usually in two D. You write on pencil on 0:12:20.840 --> 0:12:23.080 paper that's on a plane, but you can draw the 0:12:23.120 --> 0:12:25.000 lines in a way that your brain looks at them 0:12:25.160 --> 0:12:28.000 and imagines a three D object in your three D 0:12:28.200 --> 0:12:31.280 mental space. You can do sort of similar stuff drawing 0:12:31.360 --> 0:12:33.480 things in three D or even in two D to 0:12:33.600 --> 0:12:36.080 give yourself the impression of what a four D object 0:12:36.240 --> 0:12:39.240 might look like in your mind. M M, I see, 0:12:39.400 --> 0:12:42.200 Like you draw a cube, and you you draw another cube, 0:12:42.200 --> 0:12:45.600 and you connect them together somehow. Yeah, exactly, you can extrapolate, like, 0:12:45.880 --> 0:12:48.400 how do you draw a three D cube on a 0:12:48.480 --> 0:12:51.080 two D piece of paper? When you take two squares 0:12:51.520 --> 0:12:53.760 and you connect all their edges, then it looks like 0:12:53.800 --> 0:12:56.080 a cube. Right, So if you want to play the 0:12:56.120 --> 0:12:59.640 same game, now draw two cubes piece of paper and 0:12:59.720 --> 0:13:03.640 can act all of their eight edges, And that's sort 0:13:03.679 --> 0:13:06.040 of maybe what it tests rack might look like if 0:13:06.040 --> 0:13:08.480 you were four D being with four D eyes and 0:13:08.520 --> 0:13:11.880 a four D brain. M right, But I guess that's 0:13:11.880 --> 0:13:14.760 just sort of like a a drawing or a or 0:13:14.840 --> 0:13:17.520 like a spatial way to depicnic But really, I mean 0:13:17.600 --> 0:13:19.800 if there was a fourth dimension, you wouldn't see it 0:13:19.800 --> 0:13:22.560 in our three dimensions, right, Yeah, that's a great question. 0:13:22.600 --> 0:13:24.600 I mean you would see it, but you would only 0:13:24.640 --> 0:13:27.840 see a slice of it. Right. The fourth dimension, if 0:13:27.880 --> 0:13:30.360 it was a real part of space and time, wouldn't 0:13:30.400 --> 0:13:32.600 be something hidden to us. It would just be that 0:13:32.600 --> 0:13:35.320 we couldn't see all of it. You know, imagine being 0:13:35.440 --> 0:13:38.439 a two D being in a three D space. You're 0:13:38.440 --> 0:13:40.960 still seeing that three D space, You're only seeing a 0:13:41.040 --> 0:13:43.840 two D slice of it though, So things would look 0:13:43.880 --> 0:13:46.760 pretty weird if we were in a four dimensional space 0:13:46.800 --> 0:13:50.080 and we were three D beings. All right, Well, maybe 0:13:50.120 --> 0:13:53.160 let's jump into this idea of a fourth dimension. What 0:13:53.240 --> 0:13:56.640 does that even mean, Daniel? It's hard to wrap your 0:13:56.640 --> 0:13:59.680 mind around because our brains are three D objects and 0:13:59.679 --> 0:14:02.600 we've been thinking about three dimensions for so long. And 0:14:02.640 --> 0:14:05.760 you know, if you think about X, Y and Z, 0:14:06.440 --> 0:14:09.320 those are like three glowing lines in your brain that 0:14:09.360 --> 0:14:12.080 are all ninety degrees from each other. It seems like 0:14:12.120 --> 0:14:15.559 they sort of fill the universe. The whole idea behind X, 0:14:15.720 --> 0:14:17.840 Y and Z is that that's all you need to 0:14:17.880 --> 0:14:20.760 know to know where anything is. Like with if you 0:14:20.800 --> 0:14:23.800 specify the X, the Y, and the z value, then 0:14:23.880 --> 0:14:25.960 you know where something is. There's isn't the need for 0:14:26.000 --> 0:14:29.240 another direction, But now try to add a fourth dimension, 0:14:29.280 --> 0:14:32.000 Like where does it fit? You can't stick another line 0:14:32.080 --> 0:14:34.960 coming out of that axis because it would be moving 0:14:35.000 --> 0:14:37.200 through three D space. So you have to like take 0:14:37.280 --> 0:14:41.200 this sort of mental leap and imagine a whole other direction. 0:14:41.640 --> 0:14:44.440 So imagine like a family of these X, Y, Z 0:14:44.560 --> 0:14:48.840 axes and the relationship between those is the fourth dimension. 0:14:48.880 --> 0:14:50.720 So you can move from like one access to another 0:14:50.760 --> 0:14:55.000 access to another access. That's motion in this now other direction, right, 0:14:55.120 --> 0:14:57.320 and I think that maybe the interesting thing, or the 0:14:57.360 --> 0:15:00.720 tricky thing to imagine is that moving in this other 0:15:00.920 --> 0:15:04.480 fourth dimension shouldn't affect how you look like in the 0:15:04.520 --> 0:15:08.280 original three dimensions. Right, Like I can move backwards, forwards, 0:15:08.360 --> 0:15:11.400 up and down into the sides in our regular three dimensions. 0:15:11.440 --> 0:15:14.120 But then if I moved in the fourth dimension, someone 0:15:14.120 --> 0:15:16.320 looking at me right here in the room wouldn't see 0:15:16.320 --> 0:15:19.240 me move. Right. Technically, that's right, they wouldn't see you 0:15:19.280 --> 0:15:22.720 move in three D. But it depends on your shape 0:15:22.760 --> 0:15:25.600 in the fourth dimension, right, And again it's hard to 0:15:25.600 --> 0:15:27.880 think about. So it's a little easier to step down 0:15:27.920 --> 0:15:31.040 in dimensions and think about like two versus three dimensions. 0:15:31.120 --> 0:15:34.160 Imagine we were living on a two D surface and 0:15:34.360 --> 0:15:36.600 somebody passed a stick through that two D surface. What 0:15:36.640 --> 0:15:38.960 would we see. We would just see like a slice 0:15:39.000 --> 0:15:40.640 of the stick. It would look like, you know, a 0:15:40.680 --> 0:15:43.440 flat circle, and even if it was moving in that 0:15:43.520 --> 0:15:46.040 extra dimension, we couldn't tell. I think that's the example 0:15:46.120 --> 0:15:48.320 you were giving. But what if it wasn't a stick. 0:15:48.360 --> 0:15:52.160 What if it was like a pyramid or a sphere, right, 0:15:52.440 --> 0:15:55.840 and we smooved that sphere through our two D slice, 0:15:56.280 --> 0:15:58.920 then we would see a flat circle that was growing, 0:15:59.280 --> 0:16:01.600 and then would grow and we get larger as the 0:16:01.600 --> 0:16:04.000 center of the sphere passed through a plane, and then 0:16:04.040 --> 0:16:06.160 it would shrink again as the back half of the 0:16:06.160 --> 0:16:08.360 sphere pass through a plane, and then it would disappear. 0:16:08.520 --> 0:16:11.360 So motion in the fourth dimension can be visible in 0:16:11.440 --> 0:16:15.400 your three dimensions, depending on your shape in that fourth dimension. 0:16:15.760 --> 0:16:21.560 M m m. Yeah. Like imagine, for example, that you 0:16:21.600 --> 0:16:23.520 were a three D person and I was a two 0:16:23.600 --> 0:16:26.040 D person, and I like try to put you in prison. 0:16:26.080 --> 0:16:28.360 I like build walls around you in my two D world. 0:16:28.760 --> 0:16:30.200 You would just laugh at me. You would just like 0:16:30.400 --> 0:16:33.240 step over them, right, because I'm just like drawing a 0:16:33.280 --> 0:16:35.800 box on the ground around you. It's no big deal 0:16:35.840 --> 0:16:38.400 for you to like escape my two D prison because 0:16:38.400 --> 0:16:40.280 you're a three D person. You can just like go 0:16:40.480 --> 0:16:42.920 up and over it. And from my point of view, 0:16:42.960 --> 0:16:45.400 it would be like you just disappear from my prison 0:16:45.480 --> 0:16:47.680 cell and appear on the other side of it. I 0:16:47.720 --> 0:16:50.280 wouldn't be able to understand how you had gone from 0:16:50.320 --> 0:16:53.680 inside to outside. In the same way, if a four 0:16:53.800 --> 0:16:57.040 D person is in a three D prison, in principle, 0:16:57.080 --> 0:17:00.960 they could move through that fourth dimension right and appear 0:17:01.040 --> 0:17:05.040 outside the prison. Cell Ummm. This is really hard because 0:17:05.040 --> 0:17:07.520 I feel like we're trying to describe four dimensions with 0:17:07.600 --> 0:17:13.120 one dimension, which is sound, which is a pretty impossible. 0:17:13.160 --> 0:17:15.200 But you say it sort of depends on your shape, 0:17:15.359 --> 0:17:17.879 I guess, But does that sort of depend on the 0:17:17.920 --> 0:17:21.359 idea that you are projecting onto a plane or a 0:17:21.480 --> 0:17:25.040 three dimensions? Like, isn't it possible that I still am 0:17:25.040 --> 0:17:29.080 projecting onto a plane, but I'm also moving in a 0:17:29.119 --> 0:17:32.240 fourth dimension without that changing that doesn't really depend on 0:17:32.280 --> 0:17:35.360 my shape. That's totally possible, it's just not necessary. There's 0:17:35.400 --> 0:17:38.040 lots of different configurations. It's possible for you to be 0:17:38.119 --> 0:17:40.520 moving in the fourth dimension and not have any apparent 0:17:40.600 --> 0:17:43.760 motion in the third dimension, just like you know, you 0:17:43.800 --> 0:17:46.639 could be moving in Z without changing anything in X 0:17:46.680 --> 0:17:49.879 and Y and that totally works. But it's also it 0:17:50.040 --> 0:17:53.000 is possible to move in the fourth dimension and to 0:17:53.119 --> 0:17:56.359 have that motion affect how you look in three dimensions. 0:17:56.640 --> 0:17:59.879 M all right. So it's tricky and we're not quite 0:18:00.080 --> 0:18:02.680 sure how it would work, right because we sort of 0:18:02.680 --> 0:18:05.800 don't know what our shape would be in the fourth dimension. Yeah, exactly, 0:18:05.840 --> 0:18:07.800 Like I could be a really long cylinder or I 0:18:07.840 --> 0:18:10.840 could be a sphere, right, yeah exactly. Or I could 0:18:10.840 --> 0:18:14.040 be you know, a really attractive you know perimeter, yeah, 0:18:14.119 --> 0:18:15.679 or you could be shaped like a peanut. Like we 0:18:15.760 --> 0:18:18.439 just we just don't know. We have no idea, you know, 0:18:18.520 --> 0:18:21.399 if a fourth dimension exists and what our extent in 0:18:21.400 --> 0:18:24.199 that fourth dimension would be. We also don't know the 0:18:24.280 --> 0:18:27.200 nature of that dimension. Like we're imagining that fourth dimension 0:18:27.480 --> 0:18:30.880 as if it's a flat dimension that goes on forever, 0:18:31.240 --> 0:18:33.720 just like X, Y and Z, but we don't actually 0:18:33.760 --> 0:18:37.320 even know if that's true, right, Yeah, And this actually 0:18:37.359 --> 0:18:39.840 answers another question we've got from a listener almost on 0:18:39.880 --> 0:18:43.840 the same topic. Yeah, exactly. People are thinking about four dimensions, 0:18:43.920 --> 0:18:47.560 and so we had Tom right in and ask his question. Here. 0:18:47.600 --> 0:18:50.240 It is Hi, Daniel and Johai. I'm tall, and I 0:18:50.280 --> 0:18:53.359 have a question about the fourth dimension. Can life forms 0:18:53.400 --> 0:18:56.399 exist in the fourth dimension? And if so, how would 0:18:56.400 --> 0:18:59.680 we interact with them? Good question, Tom, Yeah, I think 0:18:59.680 --> 0:19:02.240 we have answered it already, right, which is that would 0:19:02.320 --> 0:19:04.119 we be able to see them? Maybe? Maybe not? It 0:19:04.200 --> 0:19:06.600 so it depends on your shape in this fourth dimension, 0:19:06.920 --> 0:19:09.119 Like you could maybe have a really long shape in 0:19:09.119 --> 0:19:12.880 the fourth dimension, or you could not, right, yeah, exactly, 0:19:12.920 --> 0:19:15.680 So it depends on the nature of that fourth dimension 0:19:15.880 --> 0:19:18.440 and our shape in that fourth dimension, like what our 0:19:18.480 --> 0:19:21.359 extent is in that dimension, And we just don't know 0:19:21.359 --> 0:19:23.840 because we can't sense or detect the fourth dimension if 0:19:23.840 --> 0:19:26.240 it exists, so we just don't really know the answer 0:19:26.280 --> 0:19:28.920 to that question. But if the universe is four D 0:19:29.119 --> 0:19:31.200 and there's a life form out there that lives in 0:19:31.200 --> 0:19:34.159 that fourth dimension as well, you know, and looks at 0:19:34.240 --> 0:19:36.199 us the way we would look at people living on 0:19:36.240 --> 0:19:38.080 the surface of a piece of paper, then you know, 0:19:38.119 --> 0:19:41.120 it would have a much more complex and nuanced relationship 0:19:41.160 --> 0:19:43.960 with that dimension, and it could probably literally run circles 0:19:43.960 --> 0:19:46.880 around us. Yeah, and what they look like, thannas, it's 0:19:46.920 --> 0:19:50.560 the question, I think. And they have purple skin, they 0:19:50.600 --> 0:19:53.440 would be glowing blue of course. All right, well, let's 0:19:53.480 --> 0:19:55.960 get into why we think there might be more than 0:19:56.000 --> 0:20:00.119 three dimensions and also what those dimensions could be. But 0:20:00.240 --> 0:20:14.600 first let's take a quick break. All right, we're talking 0:20:14.640 --> 0:20:17.840 about four dimensions, and the tests are act which is 0:20:18.040 --> 0:20:20.359 not a blue cube in a superhero movie, but a 0:20:20.520 --> 0:20:23.639 geometric shape in four dimensions. Yeah, and I guess when 0:20:23.640 --> 0:20:25.879 we say it's a cuban four dimensions, because the cube 0:20:25.920 --> 0:20:28.119 is kind of like your most basic shape. Yeah, you 0:20:28.160 --> 0:20:30.879 could also imagine a four D sphere. I suppose, right, 0:20:30.880 --> 0:20:32.760 you can play the same game. You could say you 0:20:32.840 --> 0:20:35.520 have a dot in zero dimensions, you have a circle 0:20:35.880 --> 0:20:38.840 in two dimensions, you have a sphere in three dimensions. 0:20:39.040 --> 0:20:40.760 I'm not sure what a circle would be like in 0:20:40.880 --> 0:20:43.879 one dimension, but you can go zero to three, and 0:20:43.880 --> 0:20:46.960 then I suppose you could imagine a four dimensional sphere 0:20:46.960 --> 0:20:50.040 where the surface has the same distance from the central point, 0:20:50.240 --> 0:20:53.720 including the fourth dimensional distance. I think you can play 0:20:53.880 --> 0:20:56.760 similar games in four D for other objects. But yeah, 0:20:56.760 --> 0:20:59.000 a cube is sort of like the basic thing because 0:20:59.320 --> 0:21:02.960 you're moving perpendicular in all four directions, and so it's 0:21:03.000 --> 0:21:05.560 like the building block. Yeah, well step us through. Why 0:21:05.560 --> 0:21:08.080 do we think there might be more dimensions? Is it 0:21:08.359 --> 0:21:12.200 based on theory or a hunter just just like wild possibility. 0:21:13.440 --> 0:21:18.080 It's based on wild theories from physicists gone wild, of course, Yeah, exactly. 0:21:19.440 --> 0:21:22.720 You know, sometimes it's just the math works better if 0:21:22.760 --> 0:21:25.840 you assume more dimensions, Like we try to write down 0:21:26.000 --> 0:21:29.000 theories of physics that makes sense, and sometimes they just 0:21:29.040 --> 0:21:31.840 don't really work. And it turns out if you like 0:21:31.960 --> 0:21:35.280 assume that space has more dimensions, then all of a sudden, 0:21:35.320 --> 0:21:38.320 the math gets not simpler, it gets more complicated, but 0:21:38.359 --> 0:21:41.560 it fits together in a more natural way. Really, it 0:21:41.640 --> 0:21:44.399 makes the math easier, or it makes it make more sense. 0:21:44.560 --> 0:21:47.240 Like you're doing the math and something's not fitting quite right. 0:21:47.280 --> 0:21:49.359 But if you added a whole new dimension, you know, 0:21:49.560 --> 0:21:53.080 things would be smoother, exactly. And one of the places 0:21:53.160 --> 0:21:55.639 this comes up is in trying to understand the universe 0:21:55.680 --> 0:21:58.720 that a really really small scale, you know, down deep 0:21:58.760 --> 0:22:03.040 below atoms, below, nuclei, below protons, below, quarks, much much 0:22:03.080 --> 0:22:05.760 deeper down the very smallest scale. We don't know what 0:22:05.840 --> 0:22:08.840 the nature of the university is, but people have speculations, 0:22:08.880 --> 0:22:12.080 ideas business gone wild, think about how maybe it's made 0:22:12.119 --> 0:22:16.160 out of tiny little vibrating strings, and these strings vibrate 0:22:16.240 --> 0:22:19.280 in some funny dimensions, and so in order to make 0:22:19.560 --> 0:22:23.439 those calculations work, like to have those strings vibrate and 0:22:23.480 --> 0:22:27.600 have those vibrating strings turn into particles. At our scale, 0:22:27.880 --> 0:22:30.439 you need more ways for those strings to vibrate. You 0:22:30.440 --> 0:22:32.480 need for them to be able to wiggle in certain ways, 0:22:32.520 --> 0:22:34.720 and to make sheets when they wiggle, and to make 0:22:34.800 --> 0:22:38.160 complicated structures, and those structures make a lot more sense. 0:22:38.200 --> 0:22:41.440 It turns out if the universe has something like eleven 0:22:41.480 --> 0:22:45.960 dimensions rather than just three, because with only three dimensions, like, 0:22:46.080 --> 0:22:48.400 what's the problem, you can't get sort of the richness 0:22:48.440 --> 0:22:50.480 that you see in our universe. Yeah, you don't get 0:22:50.480 --> 0:22:52.600 the richness, you don't get the results you want. And 0:22:52.640 --> 0:22:55.679 also sometimes things just collapse, Like if you try to 0:22:55.760 --> 0:22:58.800 do calculations in string theory and go for more than 0:22:58.840 --> 0:23:02.920 eleven dimensions, like up to twenty four or thirty nine dimensions, 0:23:03.040 --> 0:23:05.440 that it always just sort of ends up collapsing back 0:23:05.520 --> 0:23:08.800 down to eleven dimensions. It's just like the most natural 0:23:08.840 --> 0:23:12.280 way to express some of these theories is in eleven dimensions, 0:23:12.320 --> 0:23:14.880 and that makes us wonder, like, wells that just mathematics 0:23:14.960 --> 0:23:18.520 or is that actually reflecting something fundamental about the universe? 0:23:18.640 --> 0:23:20.399 You know, often if physics were doing this, we're like 0:23:20.760 --> 0:23:23.280 noticing a pattern about the way things seem to work 0:23:23.320 --> 0:23:27.439 mathematically and wondering, who does that reflect something real in 0:23:27.520 --> 0:23:30.520 the universe. Is that like how we're discovering something about 0:23:30.560 --> 0:23:32.639 the structure of the universe or is this just the 0:23:32.640 --> 0:23:34.960 way we write things down because we're humans and that's 0:23:34.960 --> 0:23:37.600 where our brains work, And you know, it's a deep question. 0:23:37.640 --> 0:23:39.800 We just don't know the answer to right, is it 0:23:39.880 --> 0:23:42.160 maybe just physicists not wanting to do any more math? 0:23:43.400 --> 0:23:47.000 That's just add more dimensions? Why not more dimensions? This 0:23:47.119 --> 0:23:49.960 more math, man, it makes it more complicated. You know, 0:23:50.160 --> 0:23:54.080 eleven dimensional integral it's like, you know, eleven times harder 0:23:54.080 --> 0:23:57.280 than a three dimensional integraw. But yeah, sometimes the math 0:23:57.359 --> 0:23:59.960 just works. And it also makes for a cooler grand 0:24:00.080 --> 0:24:04.040 title grant application form. Yeah, but the money you get 0:24:04.040 --> 0:24:06.000 from that grant then gets thinner and thinner because it 0:24:06.000 --> 0:24:09.920 spreads out through all eleven dimensions, it gets diluted. Yeah, 0:24:10.080 --> 0:24:13.720 but you can build a grant in more dimensions than three. Yeah, 0:24:13.760 --> 0:24:16.040 maybe we can find funding agencies that work in these 0:24:16.080 --> 0:24:18.320 other dimensions as well. All right, Well, there's also this 0:24:18.480 --> 0:24:22.920 other idea that maybe more dimensions explains gravity in some way, right, 0:24:23.000 --> 0:24:25.879 like why gravity seems so weak? Or how can we 0:24:26.000 --> 0:24:31.880 kind of resolve this conflict between special relativity and quantum physics. 0:24:32.280 --> 0:24:35.160 There's other excuses for adding more dimensions. It's a really 0:24:35.200 --> 0:24:37.920 tempting idea for lots of reasons. And one is, you say, 0:24:38.000 --> 0:24:40.920 is to explain this mystery of gravity. You know, of 0:24:41.040 --> 0:24:45.119 all the fundamental forces, the strong force, the weak force, electromagnetism. 0:24:45.400 --> 0:24:48.040 Gravity is the weakest, and not by a little bit, 0:24:48.280 --> 0:24:50.840 but like ten to the thirty. So it's just like 0:24:51.280 --> 0:24:54.840 so much weaker than the other forces. And we physicists 0:24:54.840 --> 0:24:56.640 we like harmony. We like things to sort of fit 0:24:56.720 --> 0:25:00.119 together and be explainable as part of a package. When 0:25:00.200 --> 0:25:02.080 one thing really sticks out, we don't like that. We 0:25:02.119 --> 0:25:04.720 look for an explanation for why that might be. And 0:25:04.760 --> 0:25:07.520 as you say, the idea is that gravity might not 0:25:07.640 --> 0:25:10.480 actually be super weak. It might just seem like it's 0:25:10.480 --> 0:25:13.760 super weak because it's spreading out in these other dimensions. 0:25:14.000 --> 0:25:17.000 Remember that the power of gravity gets weaker as you 0:25:17.040 --> 0:25:19.960 get further away from something. Currently, we measured that to 0:25:20.000 --> 0:25:22.679 be like one over the distance squared, But if you 0:25:22.720 --> 0:25:25.879 actually had more dimensions than just three, then the distance 0:25:25.920 --> 0:25:28.399 would grow more rapidly because you'd be moving away in 0:25:28.480 --> 0:25:32.080 more dimensions. So if gravity actually moves through all these 0:25:32.119 --> 0:25:34.960 other dimensions as well, then the reason it feels weak 0:25:35.040 --> 0:25:37.160 is that it's spreading out through those dimensions, that your 0:25:37.240 --> 0:25:39.800 distance from the other object is actually greater than it 0:25:39.880 --> 0:25:43.119 seems like it is in just three dimensions. So maybe 0:25:43.119 --> 0:25:45.920 gravity is just as powerful as these other forces. It's 0:25:45.960 --> 0:25:49.800 just mostly getting wasted in the other eight or whatever dimensions, 0:25:49.880 --> 0:25:52.240 And so that would be super awesome because it would 0:25:52.320 --> 0:25:55.120 let us like discover other dimensions of the universe and 0:25:55.200 --> 0:25:58.919 also solve this really deep mystery about why gravity seems 0:25:58.960 --> 0:26:01.560 so different from the other forces, right, And the idea 0:26:01.600 --> 0:26:04.359 is that the other forces, like magnetism and the strong 0:26:04.560 --> 0:26:07.400 and the weak forces, they only act in the three 0:26:07.400 --> 0:26:09.960 dimensions that we know, right, or they're like more focused 0:26:09.960 --> 0:26:13.720 in our regular dimensions and they're they're not acting in 0:26:13.760 --> 0:26:16.560 the other dimensions like gravity is, yeah, exactly, and that's 0:26:16.560 --> 0:26:18.280 a question we don't know the answer to, like why 0:26:18.320 --> 0:26:21.400 would that be? And as often happens in physics, if 0:26:21.440 --> 0:26:24.480 you have found those dimensions and discover the gravity is 0:26:24.480 --> 0:26:26.240 the only one that moved through them, then you'd be 0:26:26.320 --> 0:26:29.040 left with another, maybe deeper question, which is like, well, 0:26:29.240 --> 0:26:31.720 what's different about gravity that it moves through these other 0:26:31.760 --> 0:26:35.680 dimensions but electromagnetism doesn't and the strong force doesn't. So 0:26:35.840 --> 0:26:37.639 you know, we're never going to run out of those questions, 0:26:37.720 --> 0:26:41.360 even if we make crazy discoveries about the nature of space. Right. 0:26:41.400 --> 0:26:44.760 So basically you would wait the same in other dimensions, 0:26:44.800 --> 0:26:48.680 but your cell phone and your magnets wouldn't work. That 0:26:48.720 --> 0:26:53.760 would be inconvenient. Yeah, exactly. But it also means that 0:26:53.840 --> 0:26:56.760 gravity might be much more powerful than we thought, and 0:26:56.760 --> 0:26:59.600 that if you managed to get really really close to something, 0:26:59.640 --> 0:27:03.159 if you can, for example, two particles super duper close 0:27:03.200 --> 0:27:06.159 together so their distance actually gets very very small, that 0:27:06.280 --> 0:27:09.040 you might see that very strong gravity. And that's why 0:27:09.119 --> 0:27:11.879 people think we might make many black holes at the 0:27:11.960 --> 0:27:15.600 Large Hadron Collider, because two protons getting pushed really really 0:27:15.640 --> 0:27:19.240 close together might trigger super strong gravity and create a 0:27:19.240 --> 0:27:23.119 black hole. That's the whole idea behind making many black holes. 0:27:23.160 --> 0:27:26.159 It might actually reveal the existence of other dimensions of 0:27:26.200 --> 0:27:28.280 space and time. Hey, let's give it a try. That 0:27:28.320 --> 0:27:33.600 sounds like a good idea. Let's make black holes here. Yeah, 0:27:33.640 --> 0:27:36.720 and let's do it million times a second. Yeah, what's 0:27:36.760 --> 0:27:40.160 the worst, Like, let's just go wild, all right? Well, 0:27:40.160 --> 0:27:43.359 there's also the idea that maybe the fourth dimension or 0:27:43.480 --> 0:27:47.320 the extra dimensions are not necessarily related to space, like 0:27:47.480 --> 0:27:50.280 a direction that we can move in or kind of 0:27:50.320 --> 0:27:53.200 like wiggle around in. There's also the idea that maybe 0:27:53.200 --> 0:27:56.159 this fourth dimension is timet exactly. The way we were 0:27:56.160 --> 0:27:59.000 talking about gravity a moment ago was as a force 0:27:59.080 --> 0:28:02.080 that gets weaker as it propagates through space, and that's 0:28:02.080 --> 0:28:04.200 sort of like the quantum mechanical views like trying to 0:28:04.280 --> 0:28:07.320 understand gravity is one of the other forces and maybe 0:28:07.359 --> 0:28:09.400 finding a quantum theory of it. But you're right, there's 0:28:09.400 --> 0:28:12.840 another way to look at gravity, and that's part of relativity. 0:28:13.040 --> 0:28:16.240 And relativity tells us that there's a deep connection between 0:28:16.240 --> 0:28:19.479 the three dimensions of space that we're familiar with and time. 0:28:19.680 --> 0:28:21.639 So it's like you were saying earlier, like do the 0:28:21.680 --> 0:28:24.119 dimensions all have to be space? Could they be like 0:28:24.359 --> 0:28:28.480 flavor or color or you know, sourness or whatever. But 0:28:28.560 --> 0:28:31.080 you're right, it's cool to think about other dimensions and 0:28:31.119 --> 0:28:34.320 have them be not necessarily just motion in space, but time. 0:28:34.680 --> 0:28:37.760 And the more we learn about space and special relativity, 0:28:38.000 --> 0:28:40.920 the more it feels like time should get promoted to 0:28:41.040 --> 0:28:45.040 like one of the dimensions. Promoter. Are you saying time 0:28:45.160 --> 0:28:48.600 is lesser than space, Daniel, you're saying it needs and promotion. 0:28:49.040 --> 0:28:51.640 I'm saying it's segregated. It's like put by itself. You know, 0:28:51.680 --> 0:28:54.480 quantum mechanics likes to say the time is really separate 0:28:54.640 --> 0:28:57.440 from space, that the two things are different, and you know, 0:28:57.600 --> 0:29:00.239 space can do all sorts of things that time can't do. Like, 0:29:00.360 --> 0:29:02.200 you know, you can go backwards and forwards in space 0:29:02.240 --> 0:29:03.760 and you can't do that in time. So it would 0:29:03.760 --> 0:29:07.320 be super awesome if we understood time is actually part 0:29:07.360 --> 0:29:11.480 of some four D object, which was three spatial dimensions 0:29:11.480 --> 0:29:13.720 and this one weird time to mention. I think that 0:29:13.720 --> 0:29:16.120 would be a promotion for time to get graduated up 0:29:16.160 --> 0:29:18.800 to a full dimension. Right, but you know what is 0:29:18.840 --> 0:29:22.160 space without time? Then? You know, do you think about it? 0:29:22.160 --> 0:29:25.600 It's brief. I can exist without space or you know, 0:29:25.680 --> 0:29:28.600 time doesn't need three dimensions of space. You know, I 0:29:28.640 --> 0:29:31.040 would could hang out with two dimensions of space. Yeah, 0:29:31.040 --> 0:29:33.280 that's true. So really, I mean, I think time is 0:29:33.320 --> 0:29:39.920 just cooler. It's more, it's more timeless. It's a classic. Yeah, 0:29:39.960 --> 0:29:42.320 you know, there's something good about everybody, but it's also 0:29:42.520 --> 0:29:45.680 just cool to understand them as part of the bigger picture. 0:29:45.840 --> 0:29:48.880 And I think there's something really beautiful. They're something really 0:29:48.920 --> 0:29:51.760 deep and insightful, and understanding time is part of this 0:29:51.880 --> 0:29:54.120 for D object. You know, it's not just like, hey, 0:29:54.160 --> 0:29:57.200 there's some similarities, let's write them down together. It's that 0:29:57.320 --> 0:30:00.640 the concept makes much more sense when you put them together. 0:30:00.960 --> 0:30:04.120 Then when you leave them apart. Special relativity really shows 0:30:04.200 --> 0:30:06.640 us that it shows us that space and time are 0:30:06.720 --> 0:30:09.600 really closely connected in the same way that the three 0:30:09.640 --> 0:30:12.880 spatial dimensions are really closely connected. You know, the universe 0:30:13.000 --> 0:30:15.000 makes much more sense if you look at it in 0:30:15.160 --> 0:30:17.680 three dimensions, and it turns out it makes even more 0:30:17.840 --> 0:30:20.720 sense if you packed it all together into a four 0:30:20.760 --> 0:30:24.560 dimensional concept. Right. This is the concept of space time, right, 0:30:24.600 --> 0:30:28.240 like you treated all is one concept or one thing 0:30:28.400 --> 0:30:31.959 or one like coordinate system that we live in. Yeah, exactly, 0:30:32.000 --> 0:30:34.280 you think about it is like one coordinate system, and 0:30:34.360 --> 0:30:37.600 some things just make more sense in that coordinate system. 0:30:37.640 --> 0:30:40.280 You know. Take for example, the length of an object 0:30:40.400 --> 0:30:44.080 in three dimensional space, right, doesn't really matter how you 0:30:44.120 --> 0:30:46.640 measure it, you know, or where your axes are, how 0:30:46.680 --> 0:30:48.960 you define your X, y and z. The length of 0:30:48.960 --> 0:30:50.800 a stick is the length of a stick, and you 0:30:50.800 --> 0:30:52.760 can turn that stick around and it still has the 0:30:52.840 --> 0:30:55.320 same length, right, And that would be true if you're 0:30:55.320 --> 0:30:57.120 only looking at like a two D slice of it. 0:30:57.240 --> 0:30:58.880 If you're only looking at a two D slice of 0:30:58.920 --> 0:31:01.280 that stick, it would seem like it changing length as 0:31:01.320 --> 0:31:03.720 you like rotated it around or whatever. But we know 0:31:03.800 --> 0:31:06.400 the stick has a certain length, and so we want 0:31:06.440 --> 0:31:09.480 our measurement system to reflect that. Well, the same thing 0:31:09.600 --> 0:31:13.200 is actually true in space time. If you add time 0:31:13.520 --> 0:31:16.280 to your universe as the fourth dimension, then you can 0:31:16.360 --> 0:31:18.840 have a new definition of distance, which is called a 0:31:18.960 --> 0:31:22.240 space time interval, which is a distance in space and 0:31:22.440 --> 0:31:25.400 in time. You like add another bit to the calculation. 0:31:25.560 --> 0:31:28.160 And we know in our universe that like distance between 0:31:28.240 --> 0:31:31.000 objects is actually weird. It depends on how where you 0:31:31.040 --> 0:31:33.880 are and how fast you're going, and that the distance 0:31:33.880 --> 0:31:37.680 in time between objects depends also on how fast you're going. 0:31:37.720 --> 0:31:40.760 This is like length contraction and time dilation. The universe 0:31:40.760 --> 0:31:43.680 seems really weird, like it doesn't follow a lot of rules. 0:31:43.680 --> 0:31:46.480 It turns out in four D it does follow those rules, 0:31:46.560 --> 0:31:50.120 and like the four D space time interval, it doesn't 0:31:50.200 --> 0:31:52.680 change no matter what reference frame you're in how you 0:31:52.840 --> 0:31:55.960 rotate your measuring stick. So there are these properties, these 0:31:56.000 --> 0:31:59.280 principles that are respected only in four dimensional space and 0:31:59.360 --> 0:32:01.800 not in three dimensional space. And that's what makes us 0:32:01.800 --> 0:32:04.160 think that the four D spaces like more natural, that 0:32:04.240 --> 0:32:06.440 it's the better way to think about the universe. M 0:32:07.040 --> 0:32:09.320 It's like you don't need a special kind of math 0:32:09.480 --> 0:32:11.960 or a whole different set of equations to deal with time. 0:32:12.000 --> 0:32:14.360 You can use the same equations if you treat it 0:32:14.400 --> 0:32:17.280 another dimension. Yeah, you can use the same equations, and 0:32:17.400 --> 0:32:19.440 a bunch of stuff now suddenly makes sense, and it 0:32:19.520 --> 0:32:22.320 is simple if you do the math altogether. You know, 0:32:22.360 --> 0:32:25.960 for example, our laws of physics don't change if you 0:32:26.200 --> 0:32:29.720 rotate them in four dimensional space. What that means is 0:32:29.760 --> 0:32:32.840 that they're the same for everybody in an inertial reference frame. 0:32:32.880 --> 0:32:35.440 It doesn't matter where you are and how fast you're going. 0:32:35.800 --> 0:32:39.400 You can always apply the same laws of physics, electromagnetism 0:32:39.400 --> 0:32:41.520 and the strong force. All that can be applied no 0:32:41.560 --> 0:32:44.200 matter who you are and how fast you're going. That's 0:32:44.240 --> 0:32:46.560 not true. If you ignore that fourth dimension, you're like 0:32:46.800 --> 0:32:49.920 missing part of the story. Mmmmm, I guess It's kind 0:32:49.920 --> 0:32:52.600 of like if I'm sitting here doing nothing, you know, 0:32:52.680 --> 0:32:55.280 taking it up. Maybe it doesn't look like I'm moving 0:32:55.280 --> 0:32:57.880 in the three special dimensions, but I'm actually sort of 0:32:58.000 --> 0:33:01.880 moving in the time dimension right, Yes, yes, exactly. And 0:33:01.960 --> 0:33:06.680 the distance between your like spacetime locations right can be 0:33:06.760 --> 0:33:10.200 measured in that four dimensional space. You have zero distance 0:33:10.600 --> 0:33:12.440 in x, y and z, but you have a non 0:33:12.520 --> 0:33:15.560 zero distance in time, right, So it only looks like 0:33:15.560 --> 0:33:18.959 I mean lazy and inactive, But really I'm like working 0:33:19.000 --> 0:33:21.480 out in the time dimension, right, I'm like going for 0:33:21.520 --> 0:33:25.240 a job. You're getting strong in time exactly. And somebody 0:33:25.280 --> 0:33:28.360 else flying by near the speed of light might have 0:33:28.400 --> 0:33:31.680 a different opinion about exactly when one event happened, but 0:33:31.760 --> 0:33:34.720 they would make the same measurement of your space time interval, 0:33:34.920 --> 0:33:37.760 your distance, and four dimensions between the beginning of your 0:33:37.760 --> 0:33:41.040 workout and the end of your workout. I see, I 0:33:41.040 --> 0:33:44.520 would look good no matter how fast you're going. Yes, 0:33:44.760 --> 0:33:48.560 your beauty is invariant. All right, Well, let's talk about 0:33:48.920 --> 0:33:52.080 how this relates to quantum physics and special relativity, and 0:33:52.120 --> 0:33:54.960 also let's talk about how it shows up in The Avengers. 0:33:55.080 --> 0:34:09.879 But first let's take another quick break. We're talking about 0:34:09.920 --> 0:34:12.320 the tests or act Daniel, and now in the Avengers 0:34:12.320 --> 0:34:14.759 the Tests I act shows up I think in the 0:34:15.440 --> 0:34:18.920 thor movies First or or No Captain America. Maybe. Yeah, 0:34:19.000 --> 0:34:21.600 So it's this cube, right, and I think it's actually 0:34:21.800 --> 0:34:25.000 in these movies it's a vessel. It's just like holds 0:34:25.120 --> 0:34:29.120 the space stone, one of these six infinity stones, and 0:34:29.200 --> 0:34:32.240 so like somebody at some point earlier on the Marvel 0:34:32.400 --> 0:34:35.680 Universe took the Infinity Stone and put it inside this 0:34:35.880 --> 0:34:38.520 cube which they call a test Aract to make it 0:34:38.600 --> 0:34:41.640 like sound awesome in science, right, I think it's called 0:34:41.680 --> 0:34:44.359 making it up as you go along in terms of 0:34:44.400 --> 0:34:49.160 the writing craft there. But yeah, it turns out that 0:34:49.200 --> 0:34:51.640 the talk connected and in particularly the tests I act 0:34:51.719 --> 0:34:54.000 and this one is the space Stone, right, like it's 0:34:54.000 --> 0:34:57.040 somehow control space and lets you like create warm holes 0:34:57.160 --> 0:34:59.319 and things like that. Yeah, the space Stone has a 0:34:59.360 --> 0:35:01.720 lot of power unless you do all sorts of crazy stuff. 0:35:01.800 --> 0:35:04.640 And so the space Stone itself is not the tests Irac, 0:35:04.719 --> 0:35:06.960 but the tests Ract is this thing which holds it 0:35:07.160 --> 0:35:09.239 and you know, test React we know now is a 0:35:09.239 --> 0:35:12.160 four dimensional cube, but in the Avengers movie they use 0:35:12.200 --> 0:35:14.520 a three D cube because I guess, you know, it's 0:35:14.560 --> 0:35:16.759 harder to write a four D cube or even the 0:35:16.760 --> 0:35:19.920 special effects that Marvel Studios can't do four D movies, 0:35:20.440 --> 0:35:22.319 and so it's really just a three D C but 0:35:22.360 --> 0:35:25.440 it's glowing blue, right, So maybe in the Marvel movies, 0:35:25.520 --> 0:35:29.200 color is the fourth dimension. Well, technically if you're watching 0:35:29.239 --> 0:35:31.640 in three D, you are watching a four D movie 0:35:31.680 --> 0:35:35.600 because it is playing out in time that's true, right, Yeah, 0:35:35.680 --> 0:35:38.920 exactly right. So if you saw the Avengers in three D, 0:35:38.960 --> 0:35:41.239 you probably did see a four D test a rack 0:35:41.400 --> 0:35:44.680 containing the Space Stone. So congrats to you. Right, and 0:35:44.719 --> 0:35:47.000 then I see your notes here that it's powered by 0:35:47.080 --> 0:35:49.400 dark energy, where they just like throwing all kinds of 0:35:49.400 --> 0:35:52.840 physics terms in there to try to impress people. Yeah, exactly. 0:35:52.880 --> 0:35:55.640 I don't know who the science consultant was for that movie, 0:35:56.000 --> 0:35:58.239 but you know, they give them a broad introduction to 0:35:58.320 --> 0:36:00.640 everything about the universe, and they just like cherry picked 0:36:00.680 --> 0:36:03.759 the words that sounded cool, and hey, dark energy does 0:36:03.840 --> 0:36:05.920 sound cool. So it's nice to know that if the 0:36:05.960 --> 0:36:09.160 Space Stone were real, it would be somehow powered by 0:36:09.200 --> 0:36:13.040 this mysterious force that's accelerating the expansion of the universe. 0:36:13.320 --> 0:36:16.920 I might have to marvel a fact check that. I 0:36:16.960 --> 0:36:19.160 think maybe it was another stone that was powered by 0:36:19.239 --> 0:36:23.839 dark energy, maybe the Red one. Maybe I'm not quite sure. Yeah, 0:36:23.880 --> 0:36:26.440 you you certainly might be right. I just remember watching 0:36:26.440 --> 0:36:29.680 this movie and going, oh, dark energy, that sounds fun. 0:36:30.920 --> 0:36:32.840 Now you were watching in black and white or something. 0:36:33.480 --> 0:36:37.160 Maybe I was watching it backwards in time accidentally, right, 0:36:38.160 --> 0:36:40.440 And it also shows up in other words, right, and 0:36:40.520 --> 0:36:42.960 the wrinkle in Time books, right, Yeah, The Wrinkle in 0:36:43.040 --> 0:36:45.280 Time is a really fun book which recently made into 0:36:45.280 --> 0:36:48.319 a pretty good movie. And in that book they can 0:36:48.360 --> 0:36:52.360 travel all around the universe and they call the fifth 0:36:52.360 --> 0:36:55.080 dimension a test I act. So like a tests iact 0:36:55.280 --> 0:36:57.440 is a four D cube in our universe, but in 0:36:57.640 --> 0:37:01.200 a Wrinkle in Time universe, the whole fifth dimension is 0:37:01.239 --> 0:37:03.759 a tests iract and you can like add that to 0:37:03.880 --> 0:37:07.400 other four dimensions as you travel through space without like 0:37:07.480 --> 0:37:09.880 having to go the long way around. So it's sort 0:37:09.880 --> 0:37:13.120 of like a portable wormhole you can use to get 0:37:13.239 --> 0:37:16.040 from one spot to the other. Wait, what the fifth 0:37:16.040 --> 0:37:19.160 dimension is actually a four dimensional cube? In that movie, 0:37:19.200 --> 0:37:20.960 they sort of brush over the tests Iract as a 0:37:21.000 --> 0:37:23.320 four D cube and they just call the tests Iract 0:37:23.320 --> 0:37:26.799 the fifth dimension. And so imagine if like space and 0:37:26.920 --> 0:37:29.360 time are four dimensions, and you wanted to get to 0:37:29.440 --> 0:37:32.279 somewhere else in the universe, and you wanted to do 0:37:32.320 --> 0:37:35.120 it without going through four D space, if you could 0:37:35.160 --> 0:37:37.600 somehow move in the fifth dimension, if the universe is 0:37:37.680 --> 0:37:40.919 like bent in the fifth dimension, so that you could 0:37:40.960 --> 0:37:43.320 like hop from one part of our four D sheet 0:37:43.400 --> 0:37:45.680 to another part of the four D sheet by moving 0:37:45.760 --> 0:37:49.160 in that fifth dimension. That's sort of like what wormholes 0:37:49.239 --> 0:37:51.680 do in our universe. So it's sort of like, you know, 0:37:51.719 --> 0:37:54.279 a little shortcut, m I see. It's kind of the 0:37:54.320 --> 0:37:57.520 idea that maybe, like here where we are now is 0:37:57.840 --> 0:37:59.880 and Jupiter, which is really far away or we think 0:38:00.120 --> 0:38:02.480 really far away, could be really close to each other 0:38:02.760 --> 0:38:06.439 in another dimension, right Like if I could somehow reach 0:38:06.480 --> 0:38:08.640 out in another dimension, maybe I could just reach out 0:38:08.640 --> 0:38:12.799 and touch Jupiter exactly. Imagine our universe again, just as 0:38:12.800 --> 0:38:15.440 a sheet and then like roll it up. Then all 0:38:15.480 --> 0:38:19.480 of a sudden, you're close to another layer of that sheet. 0:38:19.760 --> 0:38:22.000 And if you like went through our universe space, it 0:38:22.040 --> 0:38:24.440 would take you forever to get there. But you know, 0:38:24.560 --> 0:38:27.600 in this like other direction, the direction in which our 0:38:27.680 --> 0:38:30.400 universe is like a rolled up sheet or folded or whatever, 0:38:30.600 --> 0:38:32.560 then you could just hop from one part of the 0:38:32.560 --> 0:38:35.000 sheet to the other, moving in that other dimension. But 0:38:35.200 --> 0:38:37.640 you know, we don't know that that dimension exists, but 0:38:37.760 --> 0:38:40.480 in a ringle in time, it does exist. So it's 0:38:40.480 --> 0:38:42.960 sort of this like cool wormhole strategy. But for a 0:38:43.000 --> 0:38:44.960 reason that just really doesn't make any sense to me 0:38:45.080 --> 0:38:47.680 other than that it sounds cool and science e They 0:38:47.760 --> 0:38:51.719 call that fifth dimension the tests I Act, right, And 0:38:51.760 --> 0:38:54.160 it also shows up in the inter Sellar movies, right, 0:38:54.200 --> 0:38:56.919 like Matthew McConaughey goes into a black hole and he's 0:38:56.920 --> 0:39:00.239 somehow like navigating a tests I act where time is 0:39:00.280 --> 0:39:03.920 another dimension and he's able to like send messages to 0:39:04.040 --> 0:39:07.200 his daughter in the future. Right, Yeah, there is some 0:39:07.280 --> 0:39:11.120 weird stuff where Interstellar you go into the black hole 0:39:11.400 --> 0:39:14.359 and space and time are all twisted up. And it's 0:39:14.360 --> 0:39:17.800 certainly true that in a black hole, space and time 0:39:17.880 --> 0:39:20.640 are a very confusing, right, and like time and space 0:39:20.640 --> 0:39:24.400 sort of like switch relationships, and space is only forwards, 0:39:24.680 --> 0:39:27.120 you know. Outside of the black hole, time can only 0:39:27.120 --> 0:39:29.879 move forwards. Inside the black hole, you can only move 0:39:30.040 --> 0:39:33.920 sort of one direction in space, sort of forwards towards 0:39:33.960 --> 0:39:37.720 the singularity. As some people say that inside the black hole, 0:39:38.000 --> 0:39:40.680 space has become time, like so I think that's the 0:39:40.719 --> 0:39:43.239 origin of that. But in the movie, you know, he 0:39:43.280 --> 0:39:46.600 can then like move through time, but he moves through 0:39:46.640 --> 0:39:49.360 time as part of the story, so there still is time. 0:39:49.400 --> 0:39:51.759 There's like a time when he was earlier in time 0:39:51.760 --> 0:39:54.440 and a time when he was later in time. You know, honestly, 0:39:54.440 --> 0:39:57.600 it doesn't make any actual sense, but it's uh, you know, 0:39:57.719 --> 0:40:01.360 it makes for a poignant scene. You mean, Christopher Nolan 0:40:01.400 --> 0:40:05.080 movie doesn't make sense with regards to time. That's so weird. 0:40:05.880 --> 0:40:08.920 You know. I recently watched Tenant, which is really fun, 0:40:09.000 --> 0:40:11.520 but I had the impression the whole time that like, wow, 0:40:11.680 --> 0:40:14.040 I either I am not following because I'm not smart enough, 0:40:14.360 --> 0:40:17.000 or this makes no sense and I can't tell which 0:40:17.000 --> 0:40:21.000 it is. You couldn't tell, really tell, And I try 0:40:21.040 --> 0:40:22.479 to map it out and try to watch a scene 0:40:22.480 --> 0:40:24.560 by scene and be like, Okay, what's going on here? 0:40:24.920 --> 0:40:27.040 How does that make sense? Trying to build a map 0:40:27.080 --> 0:40:29.160 of like what's going on in that universe? But wow, 0:40:29.200 --> 0:40:31.200 it's very confusing, And eventually I just went on to 0:40:31.239 --> 0:40:33.080 read it, and of course somebody else had watched the 0:40:33.120 --> 0:40:35.480 movie like a hundred times and built a map. But 0:40:35.560 --> 0:40:38.160 even still, it's very confusing because it's hard to think 0:40:38.200 --> 0:40:42.600 about things moving backwards in time as the story moves forwards. Right, Yeah, 0:40:42.880 --> 0:40:45.880 I think the movie lost me at backwards oxygen. I 0:40:45.920 --> 0:40:51.040 was like, you need backwards oxygen to survive living backwards. 0:40:51.480 --> 0:40:52.759 I don't know how where are they going to get 0:40:52.760 --> 0:40:56.880 to so much oxygen backwards? Anyways? Yeah, so it shows 0:40:56.920 --> 0:40:59.600 up a lot in popular culture and movies and books, 0:40:59.760 --> 0:41:02.319 But extrat dimensions and the test arc are sort of 0:41:02.360 --> 0:41:04.439 real things that physicists are thinking about. Right, It might 0:41:04.560 --> 0:41:08.600 explain gravity, might explain how quantum mechanics and general relativity 0:41:08.600 --> 0:41:11.000 are connected. Right, it's a it's like a real thing. 0:41:11.160 --> 0:41:13.440 It's a real thing. It might be a real thing. Yeah, 0:41:13.480 --> 0:41:16.160 it's a real thing in science, and that it's a 0:41:16.280 --> 0:41:19.160 very valuable and useful way to think about the universe. 0:41:19.480 --> 0:41:22.040 And there's a larger lesson there, right, that we don't 0:41:22.080 --> 0:41:24.640 know the deep nature of the universe, and we keep 0:41:24.680 --> 0:41:27.880 making the same mistake as humans by imagining that the 0:41:28.000 --> 0:41:31.000 universe is the way we always thought it was. And 0:41:31.040 --> 0:41:33.359 so it's very healthy to try to like break out 0:41:33.360 --> 0:41:36.680 of the confines of our intuition and imagine different ways 0:41:36.719 --> 0:41:40.000 the universe might be. And this is a pretty deep one. 0:41:40.320 --> 0:41:42.239 So we'd like to be open minded about the nature 0:41:42.239 --> 0:41:44.680 of the universe and not just be stuck in three dimensions. 0:41:44.800 --> 0:41:46.759 And I think that's how we made this leap to 0:41:46.960 --> 0:41:50.000 thinking about the universe in four dimensions. This connection and 0:41:50.080 --> 0:41:53.440 special relativity between space and time really does show us 0:41:53.640 --> 0:41:56.160 that time is deeply connected to space in a way 0:41:56.200 --> 0:41:59.960 that's not just mathematical, real and physical, and that whole 0:42:00.040 --> 0:42:02.840 pully might help us bridge, as you say, between relativity 0:42:02.840 --> 0:42:05.480 and quantum mechanics. Is quantum mechanics is a very very 0:42:05.520 --> 0:42:08.600 different view of time. So whatever theory we come up with, 0:42:08.640 --> 0:42:11.040 whether it's string theory or something else, to bring these 0:42:11.040 --> 0:42:13.839 together and reveal the actual nature of the universe, it's 0:42:13.880 --> 0:42:16.520 got to definitely be something that figures out time and 0:42:16.560 --> 0:42:19.960 its relationship to space and all the other possible dimensions 0:42:19.960 --> 0:42:22.839 that might be out there, like they might be real. Yeah. 0:42:23.040 --> 0:42:26.160 I guess the history of science and physics and our 0:42:26.200 --> 0:42:30.040 exploration of it is that the universe is much more 0:42:30.800 --> 0:42:33.040 complex than we think it is. Right, There's more twit 0:42:33.120 --> 0:42:35.640 and what it seems like apparently, yeah, exactly. There might 0:42:35.680 --> 0:42:38.359 really be backwards oxygen and you might have to breathe 0:42:38.360 --> 0:42:41.040 it one day. Keep your mind open. Yeah, the universe 0:42:41.160 --> 0:42:44.680 might might be wilder than you think, exactly, And the 0:42:44.760 --> 0:42:47.759 universe is always builled with surprises, And so I look 0:42:47.800 --> 0:42:50.280 forward to learning about the deep nature of the universe 0:42:50.280 --> 0:42:53.640 and discovering other dimensions of space and or time. You know, 0:42:53.680 --> 0:42:55.919 we talked about other dimensions of space, but it's also 0:42:56.000 --> 0:43:00.400 possible there are the dimensions of time. What all right, 0:43:00.440 --> 0:43:05.040 let's get into that another time. Sounds good, But in 0:43:05.080 --> 0:43:07.600 the meantime we hope that answer the questions that our 0:43:07.640 --> 0:43:09.960 listeners had about the test are act and about living 0:43:10.080 --> 0:43:13.200 in four dimensions. You hope you enjoyed that. Thanks for 0:43:13.280 --> 0:43:23.799 joining us, see you next time. Thanks for listening, and 0:43:23.840 --> 0:43:26.560 remember that Daniel and Jorge explained. The Universe is a 0:43:26.600 --> 0:43:30.040 production of I Heart Radio. Or more podcast from my 0:43:30.160 --> 0:43:33.759 heart Radio visit the I heart Radio app, Apple Podcasts, 0:43:33.880 --> 0:43:36.240 or wherever you listen to your favorite shows.