WEBVTT - What is membrane theory? 0:00:07.960 --> 0:00:10.520 Hey, Daniel, have you guys figured out what's inside a 0:00:10.560 --> 0:00:11.400 black hole? Yet? 0:00:12.000 --> 0:00:14.560 Unfortunately not? Still pretty confused. 0:00:14.920 --> 0:00:17.520 Okay, it sounds like you guys need to go back 0:00:17.560 --> 0:00:19.880 to the drawing board get some new ideas. 0:00:20.520 --> 0:00:23.279 I know, but like from where the smartest people on 0:00:23.320 --> 0:00:26.479 the planet have been stuck in this question for literally decades. 0:00:26.840 --> 0:00:29.480 See that is where you are going wrong. You are 0:00:29.480 --> 0:00:34.280 looking to the smart people. If you need wacky, crazy ideas, 0:00:34.360 --> 0:00:36.960 you need to ask the wacky crazy people like me. 0:00:39.360 --> 0:00:41.199 You're saying we should go to the insane asylum and 0:00:41.240 --> 0:00:43.480 ask people what they think is inside a black hole. 0:00:43.720 --> 0:00:46.080 I think that they could come up with some good ideas. 0:00:46.159 --> 0:00:48.840 They might be insane enough in the membrane to figure 0:00:48.840 --> 0:00:49.160 it out. 0:00:51.200 --> 0:01:09.559 Insane in the brain. Hi, I'm Daniel. I'm a particle 0:01:09.600 --> 0:01:12.440 physicist and a professor at UC Irvine. And if you 0:01:12.480 --> 0:01:15.360 didn't get my Cypress Hill reference, you're officially young. 0:01:16.080 --> 0:01:22.000 I am Katie. I am not a physicist. I like animals, though, 0:01:22.520 --> 0:01:26.840 and I like the universe. And I got that reference. 0:01:26.680 --> 0:01:28.560 Because you're insane in the membrane. 0:01:28.319 --> 0:01:33.200 Exactly, just the membrane, though the rest of me is perfectly. 0:01:32.800 --> 0:01:37.880 Sane and welcome to the podcast Daniel and Jorge Explain 0:01:37.920 --> 0:01:40.520 the Universe, in which we do our best to bring 0:01:40.600 --> 0:01:44.679 this insane universe into your brain. We try to make 0:01:44.760 --> 0:01:47.600 it all make sense, from the tiniest little quantum particles 0:01:47.640 --> 0:01:52.560 to the hugest swirling accretion disks surrounding super massive black holes. 0:01:52.960 --> 0:01:56.920 We have this hunch that maybe the universe is understandable, 0:01:57.240 --> 0:01:59.920 that it's a big mathematical puzzle that we can of 0:02:00.040 --> 0:02:02.640 eventually figure it out if we put all of our 0:02:02.680 --> 0:02:06.280 brains and membranes together. And our goal on this podcast 0:02:06.400 --> 0:02:07.840 is to explain all of it to you. 0:02:08.600 --> 0:02:12.320 Now, that's another song, super Massive black Hole. I think 0:02:12.480 --> 0:02:17.280 muse soundtrack to that really sort of indie movie called Twilight. 0:02:19.280 --> 0:02:21.200 Are you sure that wasn't part of the hip hop 0:02:21.240 --> 0:02:23.200 wars in the nineties, super Massive black Hole? 0:02:24.480 --> 0:02:28.600 I couldn't say. In the nineties, I was not cool 0:02:28.720 --> 0:02:29.200 enough to know. 0:02:29.639 --> 0:02:32.400 Well, you know, maybe there are some secrets in music 0:02:32.560 --> 0:02:35.440 that can help us crack the mysteries of the universe, 0:02:35.760 --> 0:02:38.400 because you know, some people say the universe is musical 0:02:38.440 --> 0:02:41.640 and there's a connection between music and mathematics, right, So 0:02:41.680 --> 0:02:43.839 maybe we have been looking in the wrong places. 0:02:44.240 --> 0:02:47.440 Yeah, Like I've heard this in terms of string theory, 0:02:47.480 --> 0:02:50.840 where strings aren't you know, they're not like violin strings, 0:02:50.840 --> 0:02:56.120 But it's something about some like either vibration or pattern. Honestly, 0:02:56.680 --> 0:03:00.720 I do not understand it, but you know, well, I 0:03:00.720 --> 0:03:04.520 think that is interesting that there is the idea that 0:03:04.639 --> 0:03:07.800 a lot of the mysteries of the universe could be 0:03:07.840 --> 0:03:12.560 about certain frequencies or patterns, which is also what is 0:03:12.680 --> 0:03:14.800 the major components of music. 0:03:16.040 --> 0:03:19.040 Exactly, Although if you listen to Terrence Howard on Joe Rogan, 0:03:19.280 --> 0:03:21.080 it's all frequencies. 0:03:20.440 --> 0:03:22.120 Man, is all frequencies? 0:03:22.160 --> 0:03:22.480 Man? 0:03:22.680 --> 0:03:25.480 Why am I not on Joe Rogan? See, I just 0:03:25.960 --> 0:03:26.959 can say that too. 0:03:27.360 --> 0:03:30.679 I can because you believe that one times one equals one, 0:03:30.800 --> 0:03:34.320 and Terrence Howard proves that it equals to And that's 0:03:34.320 --> 0:03:36.480 why you're just not mathematically qualified to be. 0:03:38.000 --> 0:03:40.600 I just can't think outside of the box enough to 0:03:40.600 --> 0:03:43.560 not do mauth good exactly. 0:03:43.960 --> 0:03:46.800 But we are fascinated by the mysteries of the universe. 0:03:46.840 --> 0:03:49.400 We do think that there are mathematical solutions to them. 0:03:49.720 --> 0:03:52.960 Maybe they are encoded in the sonatas of Mozart. Maybe 0:03:52.960 --> 0:03:55.520 the engineers are right that it's all vibrations all the 0:03:55.520 --> 0:03:58.640 way down. But we hope that there is an explanation. 0:03:59.000 --> 0:04:00.480 And one of the biggest things and we need an 0:04:00.480 --> 0:04:03.320 explanation for is how to think about the universe on 0:04:03.400 --> 0:04:06.960 the smallest scales. What happens when things get really, really 0:04:07.000 --> 0:04:10.760 dense and really really tiny. One of the biggest puzzles 0:04:10.760 --> 0:04:13.600 in modern physics is how to put together the two 0:04:13.720 --> 0:04:18.400 pillars of our understanding of the universe, relativity and quantum mechanics. 0:04:18.720 --> 0:04:20.840 We've been banging our heads against this for almost one 0:04:20.920 --> 0:04:25.200 hundred years, basically since we've had relativity and quantum mechanics 0:04:25.400 --> 0:04:29.680 and realize that they are fundamentally incompatible at the smallest scale. 0:04:30.040 --> 0:04:31.880 And we've been trying to figure this out. And today 0:04:31.880 --> 0:04:35.159 on the podcast, we'll be exploring yet another attempt to 0:04:35.520 --> 0:04:40.400 unify relativity and quantum mechanics. So on the podcast today 0:04:40.400 --> 0:04:49.000 we'll be answering the question what is membrane theory? 0:04:49.760 --> 0:04:53.560 Okay, as a biology nerd, I'm pretty sure I can 0:04:53.720 --> 0:04:59.159 answer this. A membrane is a semi permeable barrier, So 0:05:00.520 --> 0:05:03.400 I solved it. Congratulations to me. 0:05:04.440 --> 0:05:07.320 What about the audio barrier between us and the listeners 0:05:07.720 --> 0:05:10.080 the ideas from our brains and that their brains have 0:05:10.160 --> 0:05:11.839 we permeated a membrane. 0:05:12.320 --> 0:05:16.920 I yes, why not. I don't know enough about audio 0:05:17.040 --> 0:05:21.240 engineering to say no or philosophy, so I'm gonna say yes. 0:05:21.320 --> 0:05:26.760 We're like salt ions through the airwaves, permeating the membrane, 0:05:27.520 --> 0:05:29.800 so hopefully you can reach homeostasis. 0:05:32.279 --> 0:05:34.760 So I'm not surprised that when you heard this phrase 0:05:34.880 --> 0:05:39.240 you thought of cellular membranes divisions between solutions. You want 0:05:39.240 --> 0:05:41.880 to keep osmosis from, like moving all these bits of 0:05:41.920 --> 0:05:44.960 salt over here, or using fats to keep that over there. 0:05:45.480 --> 0:05:48.760 But it's not just in biology that we have membranes. 0:05:48.760 --> 0:05:52.280 It turns out that they are fundamental concept in theories 0:05:52.320 --> 0:05:55.599 of quantum gravity. But before we dig into that, I 0:05:55.680 --> 0:05:57.960 was curious what everybody else out there thought when they 0:05:58.000 --> 0:06:02.200 heard membrane theory. As usual, I asked our cadre of 0:06:02.279 --> 0:06:05.960 volunteers to speculate on the question without the opportunity to 0:06:06.320 --> 0:06:09.240 use Google. So, if you would like to join this 0:06:09.320 --> 0:06:11.440 group of volunteers in the future, please don't be shy. 0:06:11.600 --> 0:06:15.440 Write me to questions at Danielandjorge dot com. We all 0:06:15.480 --> 0:06:18.840 want to hear what you have to say. In the meantime, 0:06:19.000 --> 0:06:22.039 check out these answers from listeners. What do you think 0:06:22.240 --> 0:06:26.240 membrane theory is here's what people had to say. That's 0:06:26.240 --> 0:06:27.599 the first time I'm hearing golfit. 0:06:27.880 --> 0:06:30.400 But if I had to guess membranes, the function of 0:06:30.400 --> 0:06:33.839 the membranes are to pass on stuff in one direction 0:06:34.000 --> 0:06:37.160 and other stuff not in the other direction. So maybe 0:06:37.200 --> 0:06:43.480 we're talking about it's a mechanism about particle coexistence through 0:06:43.680 --> 0:06:45.360 a wall of things something like that. 0:06:45.520 --> 0:06:47.200 Just to guess, what comes to mind for me on 0:06:47.240 --> 0:06:50.039 that one is that it's something that you use to 0:06:50.080 --> 0:06:52.440 separate things, like in a fuel cell car, you know, 0:06:52.520 --> 0:06:55.279 you separate components and you make energy. Maybe it's like 0:06:55.320 --> 0:06:57.440 a desalination thing where you take salt. 0:06:57.160 --> 0:06:57.719 Out of water. 0:06:58.160 --> 0:07:02.120 So maybe there's some membrane here in the universe that's doing. 0:07:01.880 --> 0:07:02.520 That in space. 0:07:03.440 --> 0:07:07.000 I'm guessing membrane theory has to do with the outside 0:07:07.040 --> 0:07:11.960 of a cell. Maybe how the membrane, you know, protects 0:07:12.000 --> 0:07:15.960 the core of the cell and how it stays intact. 0:07:16.440 --> 0:07:18.360 I think it has to do with string theory. There 0:07:18.360 --> 0:07:20.760 are strings that vibrate in there one dimension, and I 0:07:20.840 --> 0:07:25.000 think a membrane is a something similar that can have 0:07:25.080 --> 0:07:25.920 more than one dimension. 0:07:26.840 --> 0:07:32.800 See, I'm I'm definitely with the theory that everything is 0:07:32.840 --> 0:07:35.480 a cell. If you look at the universe, it's just 0:07:35.560 --> 0:07:40.280 a giant body for some kind of huge animal. You know, 0:07:40.720 --> 0:07:44.480 it makes sense, right, you're saying the universe is alive. Yeah, 0:07:44.520 --> 0:07:47.560 it's a big maybe a giant cat. I don't know. 0:07:47.640 --> 0:07:50.800 Have you ever looked at like a black cat? Right, 0:07:51.000 --> 0:07:55.200 It's it kind of has that sort of quantum mechanics 0:07:55.240 --> 0:08:00.120 and general relativity paradox. Right, it's like a fluid, it's 0:07:59.840 --> 0:08:02.880 a solid. It's sweet and loving, and then it bites you. 0:08:03.120 --> 0:08:05.640 So yeah, I think the universe could be a giant cat. 0:08:06.120 --> 0:08:09.200 And when you get down to the tiniest components there cells, 0:08:09.800 --> 0:08:11.200 and yeah, it's been solved. 0:08:11.400 --> 0:08:14.880 You're welcome and we're done, Thank you very much. Physics 0:08:15.080 --> 0:08:19.040 is over. Katie wins all of the Nobel prices. Heay, Well, 0:08:19.040 --> 0:08:22.480 we're definitely hearing from listeners the connection to biology, which 0:08:22.520 --> 0:08:25.200 makes a lot of sense, and the idea of having 0:08:25.240 --> 0:08:30.200 two dimensional surfaces or even connections to string theory. So 0:08:30.240 --> 0:08:31.760 there's a lot of good stuff in here that we're 0:08:31.800 --> 0:08:34.720 going to dig into and explain in this episode. But 0:08:35.120 --> 0:08:37.280 a plus to all the listeners. 0:08:37.200 --> 0:08:39.840 I mean, I would assume that, yes, it's probably not 0:08:40.080 --> 0:08:43.960 like a cellular membrane. But if we're talking about a membrane, 0:08:44.480 --> 0:08:49.360 I would guess it is some kind of barrier through 0:08:49.440 --> 0:08:54.720 which certain physics transactions can occur. But that would be 0:08:54.760 --> 0:08:55.439 my guess. 0:08:56.440 --> 0:08:59.520 Is this whole podcast a physics transaction? We are taking 0:08:59.559 --> 0:09:02.200 your time and exchanging it for knowledge, is like a 0:09:02.200 --> 0:09:03.560 physics transaction. 0:09:03.400 --> 0:09:06.160 You know what? That's pretty good. I think I'm wondering 0:09:06.200 --> 0:09:10.199 about the exchange rate, though, because that's that's the real issue. 0:09:10.480 --> 0:09:12.560 Yeah, I think we're too high on the jokes permit 0:09:12.640 --> 0:09:14.439 it and too low and the physics permitted so far. 0:09:14.520 --> 0:09:15.800 Let's try to flip that right now. 0:09:16.600 --> 0:09:19.079 All right, well, okay, let me have it. Like, what's 0:09:19.160 --> 0:09:20.720 going on with this membrane theory? 0:09:21.000 --> 0:09:23.480 So membrane theory is an attempt to crack the puzzle 0:09:23.760 --> 0:09:26.840 of quantum gravity. So let's start with that. What is 0:09:26.880 --> 0:09:29.160 the puzzle of quantum gravity? Why do we want to 0:09:29.160 --> 0:09:31.480 crack it? What is the issue? Why are all the 0:09:31.520 --> 0:09:33.640 smart people on the planet thinking they need to go 0:09:33.679 --> 0:09:36.080 into the insane this islum if they can't figure this out? 0:09:36.559 --> 0:09:38.600 The basic issue is we have two ways to describe 0:09:38.640 --> 0:09:42.800 the universe. There's general relativity, which tells us about space 0:09:42.960 --> 0:09:45.880 and time and energy, and the expansion of the universe 0:09:46.160 --> 0:09:48.680 describes a lot of the big stuff. It tells us 0:09:48.800 --> 0:09:51.960 how gravity works and how the universe is expanding, and 0:09:52.000 --> 0:09:54.640 how far away galaxies are getting red shifted and all 0:09:54.720 --> 0:09:57.840 that good stuff. And then we have quantum mechanics, which 0:09:57.880 --> 0:10:00.480 describes the really small stuff, the little part of goals 0:10:00.880 --> 0:10:03.640 light and all this kind of quantum fields and sort 0:10:03.640 --> 0:10:07.640 of our understanding of microscopic matter. And the issue is 0:10:07.640 --> 0:10:09.640 that we don't know how to make these two things 0:10:09.720 --> 0:10:10.880 play well together. 0:10:11.480 --> 0:10:15.559 They don't play nice because I've actually, i think I've 0:10:15.559 --> 0:10:17.480 been on the show a couple times when we talked 0:10:17.480 --> 0:10:21.200 about this conundrum, and so it seems like, you know, 0:10:21.200 --> 0:10:24.960 when you have these mathematical theories that describe each of them, 0:10:24.960 --> 0:10:28.800 it works within it. So the general relativity math works 0:10:28.840 --> 0:10:32.320 within general relativity. It seems really nice and neat and good. 0:10:32.640 --> 0:10:35.640 Same thing for quantum mechanics. But then when you try 0:10:35.679 --> 0:10:40.080 to cross the beams the math beams, suddenly it doesn't work. 0:10:40.160 --> 0:10:42.800 Like if you're trying to use general relativity math to 0:10:43.080 --> 0:10:47.840 describe what you know is observed in experiments happening on 0:10:48.040 --> 0:10:50.480 sort of the quantum level, or vice versa. It no 0:10:50.559 --> 0:10:52.600 longer works. Is that more or less? 0:10:53.280 --> 0:10:55.720 Yeah? I love crossing the math beams. That's awesome. I 0:10:55.720 --> 0:10:58.400 want a t shirt that says I'm crossing the math beams. 0:10:58.920 --> 0:11:01.760 But yeah, that's basic the idea. And remember that what 0:11:01.760 --> 0:11:04.880 we're doing in physics is trying to build a mental 0:11:04.960 --> 0:11:09.880 model that describes the universe easy. Those mental models are 0:11:09.920 --> 0:11:14.439 always imperfect. They're always incomplete, they're always simplifications. Even if 0:11:14.440 --> 0:11:17.000 you're talking about like the flight of a baseball, right, 0:11:17.080 --> 0:11:19.640 how does a baseball fly across the field? Well, I'm 0:11:19.679 --> 0:11:22.400 going to use a parabola in Newton's equations, but I 0:11:22.440 --> 0:11:24.520 can't do the calculation very easily. I have had to 0:11:24.559 --> 0:11:27.000 include air resistance, so I decide I'm not including that 0:11:27.040 --> 0:11:30.160 because it's probably not important, and really, to answer my 0:11:30.280 --> 0:11:32.120 question of whether the guy's going to catch it, air 0:11:32.120 --> 0:11:34.760 resistance doesn't matter. I'm not going to include effects of 0:11:34.840 --> 0:11:37.560 humidity and the siazillion things I could include in my 0:11:37.600 --> 0:11:40.199 model to make it a very accurate description of the 0:11:40.240 --> 0:11:42.960 universe that I don't need to to answer my question. 0:11:43.400 --> 0:11:45.880 And so the models that we build to answer questions 0:11:45.920 --> 0:11:49.520 about the universe are always incomplete, they are always approximations, 0:11:49.840 --> 0:11:52.400 but they're still very very useful. And that's the issue 0:11:52.400 --> 0:11:54.840 with quantum mechanics and general relativity is that they are 0:11:54.880 --> 0:11:59.200 two different approximate descriptions of the universe that make different approximations, 0:11:59.240 --> 0:12:03.160 different foundations assumptions that go into building those models that 0:12:03.200 --> 0:12:06.160 are incompatible, and they let us describe different parts of 0:12:06.160 --> 0:12:08.679 the universe, as you say, very very well. So if 0:12:08.720 --> 0:12:10.959 I want to talk about how two electrons scatter off 0:12:11.000 --> 0:12:13.520 of each other, I can use quantum mechanics and talk 0:12:13.520 --> 0:12:16.360 about how they interact and the virtual particles they exchange 0:12:16.440 --> 0:12:18.200 or the fields that ripple between them, and it all 0:12:18.240 --> 0:12:21.400 works out amazingly well. And that can ignore what general 0:12:21.400 --> 0:12:24.560 relativity would do in that situation because it's irrelevant. It's 0:12:24.559 --> 0:12:27.040 like the wind resistance or the humidity on the baseball. 0:12:27.200 --> 0:12:29.760 It doesn't affect the calculations, so I can ignore it. 0:12:30.440 --> 0:12:32.880 Or if I want to say, hey, how do galaxies 0:12:32.960 --> 0:12:35.520 form and how do they swirl around each other? I 0:12:35.520 --> 0:12:38.880 can use general relativity to answer those questions, and that 0:12:38.960 --> 0:12:42.000 can ignore the quantum effects because who cares what one 0:12:42.120 --> 0:12:46.240 electron does in Andromeda doesn't affect whether our galaxy is 0:12:46.280 --> 0:12:50.080 going to crash into that galaxy, general relativity dominates. The 0:12:50.160 --> 0:12:53.680 amazing thing is that in every situation in our universe 0:12:53.720 --> 0:12:56.880 you can use either quantum mechanics to explain it or 0:12:57.080 --> 0:13:00.880 general relativity and ignore the other one. A perfect divorced 0:13:00.880 --> 0:13:03.800 couple that have separated their lives and never have to interact. 0:13:03.960 --> 0:13:06.679 You know, there are no argument at McDonald's about who's 0:13:06.720 --> 0:13:11.439 taking the kid. Yeah, they're co parenting the universe. And 0:13:11.480 --> 0:13:13.840 so you might think, all right, great, what's the problem, 0:13:14.280 --> 0:13:16.920 right co parents can live in harmony without ever talking 0:13:16.960 --> 0:13:20.160 to each other. Well, there's two problems. One is that's 0:13:20.200 --> 0:13:24.600 really unsatisfying, right, Like, we want one explanation for the universe. 0:13:24.640 --> 0:13:27.559 We don't want two different explanations. We don't want a 0:13:27.640 --> 0:13:31.400 Russiaman universe where both parents tell very very different stories 0:13:31.440 --> 0:13:32.960 about what's going on. Right. 0:13:34.440 --> 0:13:34.920 I get that. 0:13:36.640 --> 0:13:39.120 We think that there is one story about the universe. 0:13:39.160 --> 0:13:41.800 There's something that's happening, and that there are rules that 0:13:41.800 --> 0:13:44.160 are being followed, and we want to know what they are. 0:13:44.280 --> 0:13:47.480 We want our best approximation of them. So it's deeply 0:13:47.559 --> 0:13:51.800 unsatisfying to have two different, incompatible theories of the universe. 0:13:52.360 --> 0:13:55.679 And also, there are moments in the universe a very 0:13:55.720 --> 0:13:58.800 few places. In times when you can't ignore one ar 0:13:58.880 --> 0:14:01.880 or the other, you need things like the heart of 0:14:01.920 --> 0:14:05.880 a black hole a singularity. In general, relativity is incompatible 0:14:06.120 --> 0:14:08.600 with quantum mechanics, which says you've got to have some 0:14:08.760 --> 0:14:12.400 fuzziness or the Big Bang or the very early universe 0:14:12.440 --> 0:14:14.720 when things were really, really hot and dense. You need 0:14:14.760 --> 0:14:17.320 the rules of quantum mechanics to describe those particles. But 0:14:17.360 --> 0:14:20.000 you can't ignore gravity because things are so hot and 0:14:20.080 --> 0:14:22.800 so dense. So we desperately want to find a way 0:14:22.840 --> 0:14:24.840 to bring these two together. But as you say, the 0:14:24.880 --> 0:14:27.640 math beings don't cross, right. 0:14:27.720 --> 0:14:30.960 I mean, it's like, as physicists you now kind of 0:14:30.960 --> 0:14:34.240 have to play as a couple's therapist, where you have 0:14:34.320 --> 0:14:38.640 these two theories that are essentially speaking different languages and 0:14:38.680 --> 0:14:42.880 they cannot come to an agreement, and they can be 0:14:42.960 --> 0:14:45.800 perfectly functional on their own, but then when they come together, 0:14:45.920 --> 0:14:50.520 they are unable to communicate. And the Yeah, I mean, 0:14:50.560 --> 0:14:55.400 it seems like resolving that difference between the two theories, 0:14:55.440 --> 0:14:58.480 like resolving why they don't work with each other, would 0:14:58.520 --> 0:15:03.880 actually reveal some big things that we just fundamentally have 0:15:04.040 --> 0:15:05.840 not understood yet about the universe. 0:15:06.080 --> 0:15:06.360 M M. 0:15:06.640 --> 0:15:09.080 You know, I've heard anecdotally about couples that don't actually 0:15:09.080 --> 0:15:11.120 speak the same language, you know, where they have like 0:15:11.160 --> 0:15:17.000 literally now yet they've fallen in love. That's actually true, 0:15:17.160 --> 0:15:18.920 they have some other love language. 0:15:18.680 --> 0:15:21.200 Hi language interpretive there. 0:15:21.320 --> 0:15:23.880 Love at first sight, right, doesn't love it first word? 0:15:24.080 --> 0:15:24.440 Yeah. 0:15:24.600 --> 0:15:27.240 Anyway, you're right that quantum mechanics in general relativity don't 0:15:27.240 --> 0:15:29.840 get along, and one of the reasons is that they 0:15:29.840 --> 0:15:32.880 are built on very different assumptions. Like general relativity says 0:15:32.880 --> 0:15:37.320 the universe is smooth, it's continuous, it's precise, there's an 0:15:37.320 --> 0:15:40.640 infinite number of locations. It says that you can divide 0:15:40.720 --> 0:15:43.920 space an infinite number of times, like relativity agrees with 0:15:44.040 --> 0:15:47.240 Zeno's paradox, right that between you and a candy store, 0:15:47.320 --> 0:15:49.640 there's always a distance that you can cut in half. 0:15:50.200 --> 0:15:52.280 Space from the point of view of general relativity is 0:15:52.280 --> 0:15:55.360 something that's smooth and continuous and you always have a 0:15:55.480 --> 0:15:59.480 very specific location, whereas quantum mechanics says not. Nothing is 0:15:59.560 --> 0:16:02.800 actually smooth and continuous. There are not infinite number of 0:16:02.840 --> 0:16:06.280 locations between any two points. Things are discrete and chunky. 0:16:06.560 --> 0:16:08.760 A beam of light is actually made up of little 0:16:08.760 --> 0:16:11.800 pieces of light, little packets of light. Everything in the 0:16:11.880 --> 0:16:16.240 universe is discrete, and it's also imprecise. None of these 0:16:16.240 --> 0:16:19.960 little packets have a precise location that have probabilities. So 0:16:20.000 --> 0:16:22.880 you see the foundations of these two theories are very 0:16:22.960 --> 0:16:25.640 very different. They start from two very different places, and 0:16:25.720 --> 0:16:29.400 so weaving them together has a lot of challenges. People 0:16:29.440 --> 0:16:32.920 have been trying to make theories of quantum gravity to say, hey, 0:16:33.000 --> 0:16:35.280 let's take gravity and try to describe it in the 0:16:35.360 --> 0:16:38.440 language of quantum mechanics. For example, think of it like 0:16:38.520 --> 0:16:42.200 a quantum field that are exchanging virtual particles. They even 0:16:42.200 --> 0:16:44.360 have a name for these particles, it would be the graviton. 0:16:44.960 --> 0:16:47.200 But when you sit down and try to do those calculations, 0:16:47.440 --> 0:16:50.280 gravity is different from the other quantum forces because it 0:16:50.320 --> 0:16:53.760 couples to itself. Everything that has energy has gravity, and 0:16:53.760 --> 0:16:56.400 so if you emit a graviton, it also feels gravity, 0:16:56.440 --> 0:17:00.000 and it emits gravitons, which emit more gravitons. You can 0:17:00.080 --> 0:17:02.640 infinite number of gravitons, and then you start to get 0:17:02.720 --> 0:17:06.360 nonsense answers. So as you say, the math beams don't cross. 0:17:06.800 --> 0:17:10.440 So in terms of gravitons, is that something that has 0:17:10.480 --> 0:17:13.560 ever been able to be studying the same way that 0:17:13.640 --> 0:17:16.000 you can study protons or is it just sort of 0:17:16.040 --> 0:17:19.320 a byproduct of this seems like this could be a 0:17:19.359 --> 0:17:23.359 thing based on the math that we have theorized about. 0:17:23.520 --> 0:17:27.840 Yeah, gravitons are purely theoretical, and they're not even coherently theoretical. 0:17:28.240 --> 0:17:31.120 Theories that have gravitons in them just don't work their 0:17:31.200 --> 0:17:33.840 problems with them, and so it's not just that we 0:17:33.920 --> 0:17:36.119 haven't seen them. We don't even understand how they would 0:17:36.160 --> 0:17:39.040 work if they did exist. And there also would be 0:17:39.080 --> 0:17:42.040 really really hard to spot, Like if you're thinking about 0:17:42.040 --> 0:17:46.880 gravitational waves from rotating black holes, for example, those are 0:17:46.880 --> 0:17:50.080 not gravitons. Those are ripples in space and time. They 0:17:50.119 --> 0:17:52.879 are like a beam of light. Gravitons would be like 0:17:52.920 --> 0:17:55.560 taking that beam of light and breaking it up into photons. 0:17:55.600 --> 0:17:57.720 So you take that gravitational wave and now break it 0:17:57.800 --> 0:18:01.959 up into tiny little gravitons. But even gravitational waves are 0:18:02.000 --> 0:18:05.200 really hard to see. Gravitons would be much much tinier, 0:18:05.640 --> 0:18:09.920 well beyond our capability. But also mathematically they just don't work. 0:18:09.920 --> 0:18:12.600 If you try to do calculations with gravitons, you get 0:18:12.600 --> 0:18:16.080 weird answers like what's the probability that this electron is 0:18:16.119 --> 0:18:18.439 going to go left? Oh, one hundred and forty percent? 0:18:18.840 --> 0:18:21.160 What that doesn't make any sense, right, And so that's 0:18:21.200 --> 0:18:23.320 telling you that fundamentally there is a problem with the 0:18:23.359 --> 0:18:26.200 mathematics that you need to go deeper and start from 0:18:26.240 --> 0:18:29.200 something else, change one of your assumptions in order to 0:18:29.240 --> 0:18:31.240 make a working theory of quantum gravity. 0:18:31.600 --> 0:18:34.159 I mean this kind of reminds me in biology of 0:18:34.200 --> 0:18:37.199 how like the history of biology and medicine, where we 0:18:37.240 --> 0:18:40.000 would start to understand things like we would start to 0:18:40.240 --> 0:18:45.679 understand how certain medications work, or you know, understand things like, 0:18:45.720 --> 0:18:47.680 you know, a man and a woman make a baby 0:18:47.840 --> 0:18:52.440 and the like, there seems to be these germinal cells responsible. 0:18:52.480 --> 0:18:57.040 But then we didn't have the ability to get tiny 0:18:57.160 --> 0:19:00.840 enough inside the human body where we couldn't see like proteins, 0:19:00.880 --> 0:19:03.760 we couldn't see, you know, maybe we at some point 0:19:03.800 --> 0:19:07.320 could see cells, but we couldn't see DNA. So there 0:19:07.359 --> 0:19:11.680 were so many strange and interesting theories that kept circling 0:19:11.720 --> 0:19:14.200 around trying to get closer and closer to the truth. 0:19:14.600 --> 0:19:17.320 Like there were really funny ones like imagining that there's 0:19:17.400 --> 0:19:20.440 just like a tiny person inside of a sperm cell 0:19:20.480 --> 0:19:24.000 and then that grew into a baby. But essentially it's 0:19:24.040 --> 0:19:28.240 like we were able to make scientific observations, but without 0:19:28.240 --> 0:19:31.159 the ability to get small enough in terms of like 0:19:31.200 --> 0:19:34.560 we didn't have electron microscopes, we didn't have the technology 0:19:34.600 --> 0:19:38.480 or understanding to study DNA, these theories could not kind 0:19:38.520 --> 0:19:41.840 of you know, interweave until we got to that point. 0:19:42.280 --> 0:19:45.640 And that kind of seems like where, you know, sort 0:19:45.640 --> 0:19:48.240 of like what's happening with the universe. Like we're able to, 0:19:49.119 --> 0:19:52.240 you know, make all of these really interesting scientific observations 0:19:52.240 --> 0:19:56.200 and they're not necessarily wrong, but there is some fundamental 0:19:56.240 --> 0:19:59.800 aspect that it's not necessarily that it's too small to see, 0:20:00.000 --> 0:20:03.119 but it's something that we can't see yet or something 0:20:03.160 --> 0:20:06.840 that is really hard to observe that might help tie 0:20:06.880 --> 0:20:09.119 these things together exactly. 0:20:09.200 --> 0:20:13.280 And because it's a question mark, it's deeply unsatisfying to 0:20:13.280 --> 0:20:15.919 not have figured it out. We suspect that when we 0:20:16.000 --> 0:20:18.680 do figure it out, it'll be something new, something fascinating, 0:20:19.000 --> 0:20:22.760 something that tells us about the basic nature of the universe. 0:20:23.320 --> 0:20:26.320 Because it's telling us that Gr's description of the universe 0:20:26.440 --> 0:20:29.560 is wrong. Space is not just some bendable manifold and 0:20:29.600 --> 0:20:32.479 the quantum mechanics description of the universe is wrong in 0:20:32.480 --> 0:20:36.000 some important way. That's what I love about physics, because 0:20:36.200 --> 0:20:38.399 it's not just I have a model in my head 0:20:38.480 --> 0:20:40.800 that is predicting the universe. You can then look at 0:20:40.800 --> 0:20:43.080 that model and ask questions about it that are philosophical 0:20:43.119 --> 0:20:45.640 and like, huh, why does the universe work this way? 0:20:45.760 --> 0:20:47.200 Or you can look at it and say, oh, that's 0:20:47.240 --> 0:20:50.200 why time flows forwards and there's only one dimension of 0:20:50.240 --> 0:20:52.960 it in three dimensions of space. If you have that 0:20:53.040 --> 0:20:56.240 fundamental theory of the universe, we hope that those kind 0:20:56.280 --> 0:20:59.159 of answers can come from it deep insights about the 0:20:59.280 --> 0:21:02.840 very nature of reality. And for people who think like, oh, 0:21:02.880 --> 0:21:05.360 that's so weird and abstract, I mean, that's like the 0:21:05.359 --> 0:21:08.600 context of our whole lives, you know, our entire existence. 0:21:09.160 --> 0:21:12.120 Understanding the basic nature of reality of space and time 0:21:12.160 --> 0:21:14.959 and matter and energy like that is the stage of 0:21:15.000 --> 0:21:18.040 our life, the context of our existence. The stakes could 0:21:18.040 --> 0:21:19.280 literally not be higher. 0:21:19.600 --> 0:21:23.399 I mean it's interesting because I'm really curious about things 0:21:23.480 --> 0:21:27.720 like animal and human behavior, understanding them and understanding things 0:21:27.800 --> 0:21:31.280 like perception and you know, but those kinds of questions 0:21:31.320 --> 0:21:34.720 I don't see as too fundamentally different from the questions 0:21:34.720 --> 0:21:38.320 that physicists are answering, because in a way, you know, 0:21:38.600 --> 0:21:41.879 our perception of things are sort of like behaviors and stuff. 0:21:41.920 --> 0:21:44.960 That is how we're able to perceive the universe. And 0:21:45.000 --> 0:21:48.199 so these kinds of questions of understanding. Of course, the 0:21:48.240 --> 0:21:51.119 methodologies are very different, and what we find are going 0:21:51.160 --> 0:21:53.360