WEBVTT - Could spacetime be a fluid? 0:00:08.560 --> 0:00:11.760 Hey, Daniel, I have a question about the physics of space. 0:00:12.119 --> 0:00:16.040 Oh cool, I love those Space is so amazing and 0:00:16.120 --> 0:00:16.919 fun to talk about. 0:00:17.160 --> 0:00:19.759 Well, not the physics of space space, I mean like 0:00:19.800 --> 0:00:21.680 the office space of physics. 0:00:22.239 --> 0:00:25.280 What's the physics of office space? 0:00:25.520 --> 0:00:25.680 You know? 0:00:25.720 --> 0:00:28.960 I remember when I visited at CERN and I walked 0:00:28.960 --> 0:00:32.239 by the office of a physicists called John Ellis, and 0:00:32.320 --> 0:00:35.559 it was so messy, with paper stacks so high it 0:00:35.560 --> 0:00:37.320 looked almost impossible to walk in. 0:00:38.400 --> 0:00:41.520 Yeah, he is famously disorganized. 0:00:41.680 --> 0:00:44.360 Now how does that work? Do particle physicists have some 0:00:44.479 --> 0:00:47.040 kind of special trick that makes their office bigger on 0:00:47.080 --> 0:00:49.600 the inside than on the outside, you know, kind of 0:00:49.640 --> 0:00:51.080 like those Harry Potter tents. 0:00:51.920 --> 0:00:54.080 Actually, I think it might be the opposite. I think 0:00:54.120 --> 0:00:57.680 their offices are on the verge of collapsing into personal 0:00:57.720 --> 0:00:58.400 black holes. 0:00:59.040 --> 0:01:00.800 No, but that's kind of what I mean, Like black 0:01:00.800 --> 0:01:03.760 holes might have whole universes inside of him. Do physicist 0:01:03.800 --> 0:01:06.480 offices have a whole universe inside of him? And what 0:01:06.520 --> 0:01:07.560 are they doing inside of there? 0:01:07.600 --> 0:01:10.000 I don't know, but I suspect in John Ellis's office 0:01:10.160 --> 0:01:13.440 there's lots of ideas lost behind his personal event. 0:01:13.200 --> 0:01:17.240 Horizon, event horizon or mess Horizon. 0:01:17.000 --> 0:01:18.839 The disorganization Horizon. 0:01:34.280 --> 0:01:37.280 I am Jorge May, cartoonist and the creator of PhD comments. 0:01:37.440 --> 0:01:40.759 Hi, I'm Daniel. I'm a particle physicist and a professor 0:01:40.840 --> 0:01:45.000 at UC Irvine. And contrary to popular perception, I do 0:01:45.040 --> 0:01:47.320 try to keep my office kind of organized. 0:01:47.520 --> 0:01:49.680 Kinda that that sounds like a little bit of a 0:01:49.720 --> 0:01:52.880 loophole there. Yeah, my office is totally kind of organized 0:01:53.040 --> 0:01:56.200 if you set the bar really for the definition of 0:01:56.240 --> 0:01:57.280 the word organization. 0:01:57.520 --> 0:01:59.480 I didn't want to brag too much, but yes, I 0:01:59.520 --> 0:02:01.840 do like to keep my office neat and tidy. 0:02:02.160 --> 0:02:05.000 M I'm not sure that's something to brag about it. 0:02:05.600 --> 0:02:08.320 Don't they say genius is related to how messy your 0:02:08.480 --> 0:02:08.960 desk is? 0:02:09.200 --> 0:02:12.880 Yeah? Well, Obama said physical discipline leads to mental discipline, So. 0:02:13.240 --> 0:02:17.320 Yeah, well, I think Yoda said something similar. Also, organization 0:02:17.440 --> 0:02:20.960 leads to hate. Hate leads to suffering, and suffering leads 0:02:20.960 --> 0:02:21.760 to the dark side. 0:02:21.800 --> 0:02:23.760 But who do you think would win in basketball? Obama 0:02:23.840 --> 0:02:24.240 or Yoda? 0:02:24.440 --> 0:02:28.640 Yoda? I mean, I love Obama, but come on, Yoda, 0:02:28.720 --> 0:02:31.000 I can do like Super summersaults with a lightsaber. 0:02:31.160 --> 0:02:33.040 Yeah, that dude could probably dunk, that's true. 0:02:33.120 --> 0:02:36.400 Anyways, Welcome to our podcast Daniel and Jorge in the Universe, 0:02:36.480 --> 0:02:39.040 a production of iHeartRadio in which we. 0:02:38.960 --> 0:02:43.120 Do mental summersaults to try to explain the entire universe 0:02:43.240 --> 0:02:46.200 to you. We go out there into the vast stretches 0:02:46.280 --> 0:02:49.839 of empty space, wondering about what is actually out there, 0:02:49.880 --> 0:02:52.400 what it's made out of, zoom down to the very 0:02:52.480 --> 0:02:56.560 granular nature of reality itself, and ask questions about what 0:02:56.639 --> 0:02:59.040 it is, what it means, and how we can figure 0:02:59.120 --> 0:03:01.720 it all out. We zoom in, we zoom out, we 0:03:01.800 --> 0:03:05.040 zoom everywhere in the universe to try to explain everything 0:03:05.160 --> 0:03:05.519 to you. 0:03:05.680 --> 0:03:08.040 That's right, because it is a pretty amazing universe, and 0:03:08.080 --> 0:03:11.240 we like to explore the force in it, the dark 0:03:11.320 --> 0:03:15.000 side of it, and also the physics of basketball sometimes 0:03:15.040 --> 0:03:15.399 as well. 0:03:15.520 --> 0:03:17.640 You know, I wonder in the Star Wars universe you 0:03:17.680 --> 0:03:20.240 have like young Jedi. Are they playing sports with each other? 0:03:20.360 --> 0:03:23.639 Do they have some version of like Jedi quidditch where 0:03:23.680 --> 0:03:25.760 they're you know, pushing balls around with their minds? 0:03:26.000 --> 0:03:28.640 Oh, interesting question. You should write like a fan fiction 0:03:29.520 --> 0:03:33.840 bbble based on just that Harry Potter Star Wars like 0:03:33.919 --> 0:03:38.240 qui gon quidditch fan fiction for Star Wars, and throw 0:03:38.240 --> 0:03:39.200 in some brooms as well. 0:03:39.240 --> 0:03:40.800 But I'm asking a serious question. I think give a 0:03:40.840 --> 0:03:44.440 deeper knowledge of these universes than I do. Do young 0:03:44.560 --> 0:03:46.840 Jedi play some sort of ball sports with their minds. 0:03:46.920 --> 0:03:49.400 I don't see why they wouldn't. I guess I don't 0:03:49.440 --> 0:03:51.240 think it's canon. I mean, I do play with a 0:03:51.240 --> 0:03:53.360 little like a floating ball where they try to hit 0:03:53.400 --> 0:03:56.000 it with the lightsaber. Maybe may that's a sport. I 0:03:56.040 --> 0:03:58.440 don't know. We'll have to ask George Lucas. Can we 0:03:58.440 --> 0:04:00.640 get them on the podcast Lucas? 0:04:00.800 --> 0:04:03.000 Oh yeah, I totally email with George Lucas all the time. 0:04:03.120 --> 0:04:04.960 I send him all of my Star Wars ideas. 0:04:05.560 --> 0:04:07.640 Oh good, that would explain a lot. 0:04:08.240 --> 0:04:10.800 I don't get any answers, but I do email him. 0:04:10.800 --> 0:04:13.680 But it is a pretty wonderful universe. We do explore 0:04:13.720 --> 0:04:16.640 all sides of it because it's kind of a big universe. 0:04:16.680 --> 0:04:17.840 There's a lot of space in it. 0:04:17.880 --> 0:04:21.200 In fact, the universe is mostly space. The kind of 0:04:21.200 --> 0:04:23.200 thing that you're standing on and the sun that's in 0:04:23.240 --> 0:04:25.840 the sky is pretty unusual. If you're going to pick 0:04:25.880 --> 0:04:28.479 like a random spot in the universe, you're mostly going 0:04:28.560 --> 0:04:30.360 to end up in a spot without a whole lot 0:04:30.360 --> 0:04:31.360 of stuff in it. 0:04:31.480 --> 0:04:33.839 Yeah, because, as we talked about on the podcast, space 0:04:33.880 --> 0:04:37.239 it's not just emptiness, it's not nothing. It is actually 0:04:37.279 --> 0:04:40.800 a thing, the thing that can stretch, that can bend, 0:04:40.880 --> 0:04:44.040 that can slow down time. It's reactive to things, So 0:04:44.080 --> 0:04:45.360 it's not nothing exactly. 0:04:45.440 --> 0:04:47.880 We know that space is something interesting and it's a 0:04:47.920 --> 0:04:51.560 really fascinating step in our sort of multi stage exploration 0:04:51.720 --> 0:04:54.119 of the universe. You know, we start just by looking 0:04:54.160 --> 0:04:56.400 at the stuff that's around us. We ask what's that 0:04:56.520 --> 0:04:58.279 made out of? What's that made out of? What's that 0:04:58.360 --> 0:05:00.200 made out of? But we sort of never stop I'm 0:05:00.279 --> 0:05:02.320 asking those questions, and now we're at the point where 0:05:02.360 --> 0:05:04.279 we're trying to understand, like what is the thing that 0:05:04.360 --> 0:05:07.520 all the stuff is in. You know, if matter in 0:05:07.560 --> 0:05:09.840 the end is made of particles, and those particles are 0:05:09.880 --> 0:05:13.839 oscillations and quantum fields, and those quantum fields sit in space, 0:05:14.320 --> 0:05:17.479 then the next frontier of understanding really is to understand 0:05:17.600 --> 0:05:21.080 what that space itself is, and is space sitting in 0:05:21.120 --> 0:05:23.760 some sort of like meta super or subspace. 0:05:24.040 --> 0:05:27.920 Yeah, it's a very spacey question. There are many possibilities 0:05:27.920 --> 0:05:31.080 out there for what space can be. If you can't 0:05:31.080 --> 0:05:31.680 imagine that. 0:05:31.800 --> 0:05:34.919 And it's a fundamental question at the heart of modern physics. 0:05:35.000 --> 0:05:37.520 We're trying to understand quantum theory, were trying to understand 0:05:37.560 --> 0:05:40.719 relativity and gravitation, and if the nexus of those two 0:05:41.279 --> 0:05:44.880 is the fundamental mystery of what space actually is? Can 0:05:44.960 --> 0:05:47.359 it actually been to make black holes? Are black holes 0:05:47.400 --> 0:05:50.479 really black holes? Or are they something else? Why is 0:05:50.560 --> 0:05:53.520 the universe expanding? What will be its ultimate fate? At 0:05:53.600 --> 0:05:56.919 their hearts, all of these questions really are asking what 0:05:57.279 --> 0:05:59.760 is space? And what are the rules of it? What 0:06:00.120 --> 0:06:03.239 earns it? What is it fundamentally? Is it in fact 0:06:03.320 --> 0:06:06.440 fundamental or is it just a frothing, emergent phenomena of 0:06:06.480 --> 0:06:08.240 something even deeper? Yeah? 0:06:08.279 --> 0:06:10.800 And do the rules of space apply to office space? 0:06:11.960 --> 0:06:13.520 And I mean where people work, not just a. 0:06:13.520 --> 0:06:16.719 Movie Office space turns out to be mostly politics. You know, 0:06:16.760 --> 0:06:19.800 every time somebody retires here, there's like a scramble to 0:06:19.800 --> 0:06:21.320 see who gets their big office. 0:06:21.360 --> 0:06:23.800 Oh really, does it go by seniority? Like the more 0:06:23.880 --> 0:06:27.599 senior you are, the closer you are to the snack 0:06:27.680 --> 0:06:30.000 room or the restrooms, or the closer you need to 0:06:30.000 --> 0:06:31.000 be to the restroom. 0:06:31.080 --> 0:06:35.159 Perhaps, you know academics. Academics always have ladder systems and 0:06:35.240 --> 0:06:37.599 ranking systems and it's no different here. We have like 0:06:37.720 --> 0:06:41.400 many levels of being a professor. It's not just like assistant, 0:06:41.440 --> 0:06:44.120 associate and full professor. Within each of those, it's like 0:06:44.200 --> 0:06:48.120 many gradations, like full professor four or associate professor seven 0:06:48.320 --> 0:06:50.480 or whatever. So when a new office opens up, they 0:06:50.480 --> 0:06:52.960 go down the ladder and ask people at the top 0:06:53.000 --> 0:06:56.600 of the ladder if they want it or not. And ridiculously, 0:06:56.760 --> 0:06:59.640 all the offices in my building at least are different sizes. 0:06:59.680 --> 0:07:02.000 And it would have been so much simpler if just 0:07:02.120 --> 0:07:04.560 every office was the same size. I know, they made 0:07:04.560 --> 0:07:06.880 some really big ones and some really little ones. 0:07:07.040 --> 0:07:07.320 Hmm. 0:07:07.520 --> 0:07:11.000 It's almost like they wanted some drama, political drama. Maybe 0:07:11.000 --> 0:07:12.600 that was the architects revenge. 0:07:12.800 --> 0:07:14.360 Maybe it was I don't know. 0:07:14.600 --> 0:07:17.640 Isn't there some kind of like office space inertia, Like ooh, 0:07:17.680 --> 0:07:20.320 that that is a slightly bigger office, But I would 0:07:20.320 --> 0:07:22.880 have to clean my office and pack everything up to move, 0:07:22.920 --> 0:07:23.920 so maybe I'll just skip. 0:07:24.080 --> 0:07:26.280 Yeah. I do think that a lot of people don't 0:07:26.400 --> 0:07:29.480 take a bigger office just because they're happy where they are, 0:07:29.640 --> 0:07:32.320 or they don't really care, or their office is such 0:07:32.320 --> 0:07:36.040 a disaster that it's impossible to imagine moving. And I 0:07:36.040 --> 0:07:38.119 think That's also why it's sometimes hard to get people 0:07:38.120 --> 0:07:40.160 out of their offices, because if you've been in there 0:07:40.200 --> 0:07:42.360 for thirty years, you got a lot of stuff you 0:07:42.360 --> 0:07:43.080 got to move out. 0:07:43.280 --> 0:07:45.840 Are you saying there is such a thing as space inertia? 0:07:46.240 --> 0:07:48.120 Like space can have inertia. 0:07:47.840 --> 0:07:50.240 Turns out space can have politics. That's even weirder. 0:07:50.520 --> 0:07:52.200 Or can a black hole have inertia? 0:07:52.240 --> 0:07:54.960 Back to actual physics? Black holes definitely do have inertia, right, 0:07:54.960 --> 0:07:58.000 They have mass, which means that they have inertia. If 0:07:58.040 --> 0:08:00.400 you pushed on a black hole, then it's acceleration be 0:08:00.440 --> 0:08:02.200 inversely proportional to its mass. 0:08:02.240 --> 0:08:05.320 But you wouldn't actually recommend that, right, pushing a black hole? 0:08:06.080 --> 0:08:07.120 That would be not good. 0:08:07.240 --> 0:08:09.320 It depends if the black hole is headed towards our 0:08:09.360 --> 0:08:12.239 solar system, then I would say, yes, let's launch something 0:08:12.280 --> 0:08:14.400 heavy to push on the black hole so that it 0:08:14.440 --> 0:08:16.000 doesn't come through our solar system. 0:08:16.080 --> 0:08:18.080 Well, I guess what I meant is you wouldn't want 0:08:18.120 --> 0:08:21.320 to push it yourself, like send Daniel up into space 0:08:21.880 --> 0:08:23.920 having pushed on the black hole. I don't think that 0:08:23.920 --> 0:08:24.560 would end well. 0:08:24.960 --> 0:08:27.360 Am I going to get a big office out of it? Maybe? 0:08:27.400 --> 0:08:31.120 Probably? Yeah, you might have the whole black hole to yourself. 0:08:32.120 --> 0:08:33.960 That sounds great, except there are no windows, and I 0:08:34.040 --> 0:08:35.320 really like an office with a view. 0:08:35.559 --> 0:08:40.200 Well, it would be all windows except except yeah, I 0:08:40.200 --> 0:08:42.360 guess you couldn't stick your head out of the window. Mm. 0:08:42.640 --> 0:08:42.920 Yeah. 0:08:42.960 --> 0:08:45.520 But it is interesting to think about what space could 0:08:45.600 --> 0:08:48.199 be like, what is it made out of, and what 0:08:48.400 --> 0:08:49.640 actually makes space happen. 0:08:49.760 --> 0:08:52.920 Sometimes I think about scientists the way we think about 0:08:52.960 --> 0:08:57.439 fish swimming around in water, probably not even really aware 0:08:57.920 --> 0:09:01.400 that they are inside some sort of fluid because that's 0:09:01.440 --> 0:09:04.599 their entire world. It might take fish like hundreds of 0:09:04.679 --> 0:09:07.199 years or thousands of years to discover that the thing 0:09:07.240 --> 0:09:09.680 they're inside is not the fundamental nature of the universe. 0:09:09.720 --> 0:09:12.560 It doesn't exist everywhere, and it can do other kinds 0:09:12.559 --> 0:09:15.360 of things like boil and freeze and all sorts of stuff. 0:09:15.640 --> 0:09:17.840 So I wonder if we are sort of like fish, 0:09:18.160 --> 0:09:20.760 exploring the nature of space and only now discovering that 0:09:20.800 --> 0:09:23.800 it can do weird things that might have strange properties 0:09:23.840 --> 0:09:26.720 and might not even be the fundamental layer of reality 0:09:26.840 --> 0:09:27.160 so to be. 0:09:27.240 --> 0:09:34.640 On the podcast, we'll be asking the question is space 0:09:34.760 --> 0:09:37.880 time a fluid? What do you mean it's a fluid? 0:09:38.600 --> 0:09:40.000 It's certainly a gas isn't it. 0:09:40.679 --> 0:09:44.120 Well, time definitely seems to flow, so why not space time? 0:09:44.360 --> 0:09:47.800 Right, Well, it's basfinitely a solid thing. It's always there, 0:09:48.080 --> 0:09:48.880 you can rely on it. 0:09:48.960 --> 0:09:50.880 Well, back to the analogy with fish scientists, which I 0:09:50.920 --> 0:09:54.000 think probably originates with Max Tegmark. If you discover that 0:09:54.120 --> 0:09:58.240 space is more complicated than just the backdrop of the universe, 0:09:58.280 --> 0:10:00.599 and you discover that it might have other properties, it 0:10:00.679 --> 0:10:03.840 might be able to do things like flow or bubble 0:10:03.960 --> 0:10:07.400 or have different phases. And so that's a fascinating question 0:10:07.559 --> 0:10:09.760 about the nature of space itself and sort of what 0:10:09.960 --> 0:10:13.800 it can do. Can we described using the mathematics of 0:10:13.880 --> 0:10:16.480 fluids or do we need a completely different kind of 0:10:16.480 --> 0:10:18.840 mathematics to explain what space is up to? 0:10:19.000 --> 0:10:21.120 Well, it is kind of a mind blowing question to 0:10:21.120 --> 0:10:23.679 think that space time could be a fluid. It makes 0:10:23.720 --> 0:10:26.600 it seem like it's a physical thing, like it actually 0:10:26.640 --> 0:10:30.040 has like mass to it or something, or that it 0:10:30.120 --> 0:10:32.000 responds to forces and things like that. 0:10:32.120 --> 0:10:35.120 Yeah, as we'll see, space time being a fluid would 0:10:35.160 --> 0:10:38.640 give very specific predictions for how things propagate through it, 0:10:38.880 --> 0:10:42.400 how energy is spread or dissipates. So it's a really 0:10:42.520 --> 0:10:45.040 fascinating hypothesis and I know we've talked about it in 0:10:45.120 --> 0:10:48.600 the podcast before, how space time could be like a bubble, 0:10:48.760 --> 0:10:50.200 right or like a foam? 0:10:50.240 --> 0:10:51.040 Is not a fluid is it? 0:10:51.160 --> 0:10:51.240 Now? 0:10:51.280 --> 0:10:54.080 There are many theories of what space might be down 0:10:54.120 --> 0:10:56.960 at the granular level. Is it made of little pixels 0:10:57.000 --> 0:10:59.920 which are woven together with quantum entanglement into a kind 0:10:59.920 --> 0:11:02.800 of foam or do those pixels operate in a different 0:11:02.840 --> 0:11:05.839 sort of way. So this is more about, like at 0:11:05.880 --> 0:11:08.280 the fundamental level, what are the rules of how those 0:11:08.320 --> 0:11:12.360 pixels interact with each other and what phenomena emerges from that. 0:11:12.520 --> 0:11:15.080 Can you describe them using the physics of foam, or 0:11:15.080 --> 0:11:18.960 of liquids, or of ice cream, or office space bright 0:11:20.200 --> 0:11:22.160 or interpersonal politics. 0:11:21.760 --> 0:11:23.840 Or any kind of politics. Well, as usual, we were 0:11:23.880 --> 0:11:26.240 wondering how many people out there had thought about this question, 0:11:26.320 --> 0:11:29.240 had thought that maybe space time could be a fluid. 0:11:29.760 --> 0:11:32.320 So Daniel went out there as usual and ask the 0:11:32.360 --> 0:11:33.559 internet what they thought. 0:11:33.600 --> 0:11:36.600 Thanks very much to everybody who answers these questions. We 0:11:36.840 --> 0:11:40.160 love to hear your voice on the podcast, and anybody 0:11:40.240 --> 0:11:42.360 out there who wants to volunteer, please don't be shy, 0:11:42.559 --> 0:11:45.920 just write to me. Two questions at Danielandjorge dot com. 0:11:45.960 --> 0:11:47.560 So think about it for a second. Do you think 0:11:47.640 --> 0:11:51.000 space time could be a fluid? Here's what people had 0:11:51.000 --> 0:11:51.320 to say. 0:11:51.440 --> 0:11:54.240 I remember this was the argument for a theory in 0:11:54.280 --> 0:11:59.960 the Bigavon theory. So yeah, maybe spacetime could be a fluid, 0:12:00.160 --> 0:12:03.480 and that's the reason it only goes in one direction. 0:12:03.760 --> 0:12:08.880 Maybe in previous episodes, I've noticed that you say that 0:12:09.080 --> 0:12:12.800 space time can be stretched and squashed and almost like 0:12:12.880 --> 0:12:16.360 molded in that kind of way. So I always imagine 0:12:16.360 --> 0:12:22.920 space time being in some sort of matter state. So yes, 0:12:23.160 --> 0:12:26.480 I would say space time could be similar. 0:12:26.000 --> 0:12:28.880 To a fluid. I guess that space time is fluid 0:12:29.240 --> 0:12:34.240 ish because you can't put it in a jar or something, 0:12:34.600 --> 0:12:38.760 but it may behave like a fluid for some physics calculation. 0:12:39.120 --> 0:12:42.480 I don't know, man, it seems like, you know, there's 0:12:42.520 --> 0:12:44.520 waves in it, and we talk about it as some 0:12:44.559 --> 0:12:49.400 sort of foam, But like what space is the fluid occupying? 0:12:49.800 --> 0:12:52.200 That's that's a That's what gets me. I don't know. 0:12:52.640 --> 0:12:54.760 So if I think about it, what is a fluid? 0:12:54.760 --> 0:12:59.480 A fluid is a fluid will flow and it could 0:12:59.480 --> 0:13:03.720 flow very slow like a glacier is ice? You think 0:13:03.840 --> 0:13:07.840 ice is a solid but over long time scares a 0:13:07.880 --> 0:13:11.959 glacier would flow like a river, and I think space 0:13:12.040 --> 0:13:16.800 time around really massive objects like a black hole spinning 0:13:16.800 --> 0:13:21.319 black hole in particular will also get dragged around. I 0:13:21.360 --> 0:13:25.120 think it's called frame dragging, so space time itself will 0:13:25.160 --> 0:13:28.200 spin around the black hole. And I think as you 0:13:28.320 --> 0:13:33.880 go past the event horizon, doesn't space time itself kind 0:13:33.920 --> 0:13:36.600 of flow towards the singularity. 0:13:36.920 --> 0:13:40.600 I'm guessing that you could consider the curvature that some 0:13:40.760 --> 0:13:44.320 kind of and start to exert on space time could 0:13:44.360 --> 0:13:47.360 be considered blue. All right. I feel like we blew 0:13:47.400 --> 0:13:50.760 people's minds with this question. Somebody's like one of the 0:13:50.800 --> 0:13:53.680 people is like, WHOA, I don't know, man. 0:13:55.120 --> 0:13:57.640 Well, that's my favorite part of this podcast is making 0:13:57.720 --> 0:14:01.880 people explore crazy ideas, is dig deep into whether the 0:14:02.000 --> 0:14:04.720 universe could really be different from the way that we 0:14:04.800 --> 0:14:08.040 imagine it, you know, so contrary to our intuition. Those 0:14:08.040 --> 0:14:10.640 are the best kinds of discoveries. And I think these 0:14:10.679 --> 0:14:15.160 responses really reflect that kind of moment of exhilaration to 0:14:15.280 --> 0:14:17.600 imagine that the universe could be so different. 0:14:17.720 --> 0:14:22.120 I like the person to say they think it's fluid ish. Hey, 0:14:22.200 --> 0:14:25.400 that's a good answer for anything. Do you think the unerus. 0:14:25.520 --> 0:14:28.360 Is this there that way? I think it's this way ish. 0:14:28.400 --> 0:14:31.520 Hmmm, my office is organized ish. 0:14:31.160 --> 0:14:34.960 That's right. Yeah. But somebody else wrote in here that 0:14:35.400 --> 0:14:37.280 space can have ways. We know that. You know you 0:14:37.320 --> 0:14:40.920 can feel gravitational ways. We detected those. So if something 0:14:40.920 --> 0:14:42.800 can have ways in it, does that mean it's like 0:14:42.800 --> 0:14:43.320 a fluid? 0:14:43.440 --> 0:14:45.560 Yeah, it's a really good deep question. 0:14:45.520 --> 0:14:47.200 Like if you can make ripples in it, it's sort 0:14:47.240 --> 0:14:48.840 of does that mean it is a fluid? I guess 0:14:48.840 --> 0:14:50.920 you can make ripples in a gas too, or a solid. 0:14:51.040 --> 0:14:53.640 Yeah. Liquids have special kinds of mathematics that describe them, 0:14:53.640 --> 0:14:55.640 and that's what we're going to dig into. And there 0:14:55.640 --> 0:14:58.800 are even people who have tried to build liquid analogies 0:14:58.800 --> 0:15:01.760 of space time and liquid and analogies of black holes. 0:15:02.240 --> 0:15:05.320 Is a guy in Israel who builds sonic black holes. 0:15:05.720 --> 0:15:09.320 Sonic black holes. That sounds like a good definition for 0:15:09.360 --> 0:15:13.280 our podcast. We're soundways good to die. I hope we're 0:15:13.320 --> 0:15:15.480 not just speaking into the void. I hope there's somebody 0:15:15.520 --> 0:15:19.680 out there listening. Maybe we're hawking radiationing our ideas into 0:15:19.720 --> 0:15:20.280 the universe. 0:15:20.520 --> 0:15:23.920 M you mean like we're fish in a fish tank. Maybe, 0:15:24.440 --> 0:15:27.760 hopefully our soundways, are you going out there beyond the 0:15:27.760 --> 0:15:28.240 fish tank? 0:15:28.320 --> 0:15:30.440 I have some evidence that there are people out there 0:15:30.560 --> 0:15:32.640 listening and we're not trapped into a sonic black hole 0:15:32.680 --> 0:15:35.520 because we get responses from listeners. So if y'all are 0:15:35.520 --> 0:15:37.160 actually out there and we're not trapped in a sonic 0:15:37.200 --> 0:15:39.040 black hole, right back to us and confirm. 0:15:39.120 --> 0:15:41.400 What if we're all in your mind, Daniel, what if 0:15:41.440 --> 0:15:47.640 we're all like multiple personality aspects of you plot twist? 0:15:47.840 --> 0:15:50.440 It's like the plot of an m. Jamelon movie. 0:15:50.520 --> 0:15:52.080 I always wanted to be in one of his movies, 0:15:52.080 --> 0:15:53.680 so I'd be pretty happy with that outcome. 0:15:53.800 --> 0:15:56.080 But one of our responders here also asked an interesting 0:15:56.160 --> 0:15:59.160 question like if space is a fluid, what is the 0:15:59.200 --> 0:16:03.040 fluid in, Like what is it occupying? Is something holding 0:16:03.040 --> 0:16:05.760 it like a jar or a fissible. 0:16:05.600 --> 0:16:08.800 Or some sort of super space Like revealing the fundamental 0:16:08.880 --> 0:16:11.720 nature of space time really just opens us up to 0:16:11.800 --> 0:16:14.920 the next level of questions, like if space is a fluid, 0:16:15.040 --> 0:16:17.400 or if space emerges from something else, and that other 0:16:17.520 --> 0:16:20.160 thing and emerges from is more fundamental, and now we 0:16:20.160 --> 0:16:22.640 can focus all of our energy on that thing. It 0:16:22.720 --> 0:16:25.120 might be a never ending cycle where were always just 0:16:25.200 --> 0:16:29.080 digging deeper and finding deeper and deeper layers of reality. 0:16:29.120 --> 0:16:30.840 We don't know if we'll ever find some sort of 0:16:31.160 --> 0:16:34.720 bedrock fundamental nature to the universe or not, or we 0:16:34.720 --> 0:16:37.160 can always just ask, well, what's that made out of 0:16:37.240 --> 0:16:38.480 or what's that sitting in? 0:16:38.840 --> 0:16:42.480 Yeap goes on forever, and so let's start to dig 0:16:42.520 --> 0:16:45.880 our way through it. Daniel, let's explain what is space time? 0:16:45.960 --> 0:16:48.080 So the short version is we just really have no 0:16:48.200 --> 0:16:49.720 idea what space is. 0:16:50.120 --> 0:16:54.160 Boom and done, all right, thanks for joining us. It 0:16:54.240 --> 0:16:56.400 is kind of a black hole. See question Yeah, good 0:16:56.520 --> 0:16:57.960 diet on our podcast. 0:16:58.160 --> 0:17:00.680 One of the most confusing things about it is that 0:17:00.760 --> 0:17:03.960 we have very crisp and clear pictures of what space 0:17:04.080 --> 0:17:06.159 might be in the theories that we have built up 0:17:06.200 --> 0:17:08.240 about the universe, and as we've talked about in the 0:17:08.240 --> 0:17:12.040 podcast many times, we have like two pillars of modern physics, 0:17:12.080 --> 0:17:14.840 two different sets of ideas that have helped us answer 0:17:14.920 --> 0:17:16.800 questions about what's going on in the universe. We have 0:17:16.920 --> 0:17:20.960 quantum mechanics and we have general relativity. They're fundamentally inconsistent, 0:17:21.320 --> 0:17:24.040 and they each give us a very different picture of 0:17:24.080 --> 0:17:27.360 what space might be and how it works. So one 0:17:27.359 --> 0:17:29.720 of the biggest puzzles is like trying to bring these 0:17:29.760 --> 0:17:32.600 two things together to give us at least a unified 0:17:32.640 --> 0:17:35.920 picture of what space is. But as of now, nobody's 0:17:35.960 --> 0:17:36.760 been able to do that. 0:17:37.000 --> 0:17:39.080 Yeah, there are two different views, so let's do one 0:17:39.119 --> 0:17:42.920 of them at a time. What is space time according 0:17:42.920 --> 0:17:45.600 to quantum mechanics or does quantum mechanics even call it 0:17:45.680 --> 0:17:48.800 space time or does it treat space and time differently? 0:17:48.880 --> 0:17:52.639 Yeah, quantum mechanics treat space and time very differently. It 0:17:52.680 --> 0:17:56.480 treats space as the backdrop for quantum fields. It says 0:17:56.600 --> 0:18:00.440 that space is filled with these fields that can oscillate, 0:18:00.560 --> 0:18:03.440 and we have great equations that describe exactly how they 0:18:03.480 --> 0:18:06.560 oscillate and buzz, and you can use those equations to 0:18:06.720 --> 0:18:10.080 explain how electrons fly through space and how they radiate 0:18:10.080 --> 0:18:12.800 photons which are absorbed by other particles. And so far 0:18:12.840 --> 0:18:16.160 it seems like a super duper accurate description of what's 0:18:16.200 --> 0:18:18.560 going on in the universe. We've done amazing experiments to 0:18:18.640 --> 0:18:20.840 validate this description of the universe and compare it to 0:18:20.920 --> 0:18:23.720 quantum mechanics predictions, which agreed to like eight or nine 0:18:23.840 --> 0:18:26.680 decimal places. It's really super impressive. But the picture of 0:18:26.720 --> 0:18:29.240 space and quantum mechanics is just sort of like the backdrop. 0:18:29.280 --> 0:18:31.879 It's where the fields are. You know, we do the 0:18:31.880 --> 0:18:34.920 mathematics of quantum field theory. We write these fields as 0:18:34.960 --> 0:18:38.159 a function of space. We say every location in space 0:18:38.359 --> 0:18:40.800 has a value of these fields, or if it's a 0:18:40.880 --> 0:18:44.560 vector field, multiple values. There are like these numbers embedded 0:18:44.640 --> 0:18:47.280 in space. The time is different. Time just tells us 0:18:47.280 --> 0:18:50.359 how those fields change. And one really important thing about 0:18:50.600 --> 0:18:53.560 time in quantum mechanics is that it should be infinite. 0:18:53.960 --> 0:18:56.679 Like quantum mechanics says that the universe should have always 0:18:56.680 --> 0:19:00.800 existed and should always exist because information in the universe 0:19:00.920 --> 0:19:03.200 can't be lost, it can't just go away. And so 0:19:03.240 --> 0:19:05.159 if you take the shorten your equation, for example, and 0:19:05.240 --> 0:19:07.199 use it to describe the universe, you can run it 0:19:07.240 --> 0:19:10.240 backwards and forwards in time to infinity. And that actually 0:19:10.280 --> 0:19:13.200 tells you something about space itself, because it says that 0:19:13.359 --> 0:19:17.160