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Cards issued by JP 0:01:51.920 --> 0:01:55.920 Morgan Chase Bank NA Member FDIC subject to credit approval Offer, 0:01:56.000 --> 0:01:57.800 subject to change Terms apply. 0:02:05.440 --> 0:02:08.280 Hey, Orge, do you think our podcast episodes are getting 0:02:08.320 --> 0:02:09.360 like a little too long? 0:02:10.200 --> 0:02:11.480 Are they longer than it used to be? 0:02:11.919 --> 0:02:14.040 You know, we used to start out around forty ish 0:02:14.080 --> 0:02:16.440 minutes and some of the recent ones been hitting an hour. 0:02:17.480 --> 0:02:20.639 But not the ones with me in it right, I'll 0:02:20.680 --> 0:02:21.560 just try to keep it short. 0:02:22.760 --> 0:02:25.120 You ask a lot of questions, and sometimes it takes 0:02:25.160 --> 0:02:26.280 an hour to explain them all. 0:02:26.760 --> 0:02:28.799 I guess we are trying to explain the whole universe, 0:02:28.919 --> 0:02:30.600 so that's supposed to take a while. 0:02:31.240 --> 0:02:34.239 Yeah, it's actually amazing if you can explain like a 0:02:34.320 --> 0:02:37.160 whole year's worth of physics in like sixty minutes. 0:02:37.440 --> 0:02:40.079 Yeah. And the funny thing is that I usually forget 0:02:40.080 --> 0:02:41.320 it within sixty seconds. 0:02:43.680 --> 0:02:45.519 That's where you got to listen to it sixty times. 0:02:45.800 --> 0:02:47.640 But then I'll give it when sixty of the attention 0:02:47.720 --> 0:02:50.799 it needs to. Hey, we're done after an hour, right. 0:02:52.240 --> 0:02:53.280 I think the math works out. 0:02:53.320 --> 0:02:56.160 Yeah, yeah, I do pay attention to math. 0:03:11.440 --> 0:03:11.560 Hi. 0:03:11.639 --> 0:03:13.320 I am Poor Hee May, cartoonist and the author of 0:03:13.360 --> 0:03:14.880 Oliver It's Great, Big Universe. 0:03:15.000 --> 0:03:17.880 Hi. I'm Daniel. I'm a particle physicist and a professor 0:03:17.960 --> 0:03:21.160 at UC Irvine, and I'm very conscious of our finite 0:03:21.160 --> 0:03:21.919 amounts of time. 0:03:22.160 --> 0:03:25.079 You mean, like here on Earth or on the air. 0:03:25.919 --> 0:03:30.080 Yeah, both, Absolutely, we're spending a non trivial amount of 0:03:30.080 --> 0:03:32.200 time on Earth on the air, now that we've done 0:03:32.240 --> 0:03:34.720 so many episodes, you know, it's like a non zero 0:03:34.800 --> 0:03:38.400 fraction of our lives we spent doing this podcast. Yeah, 0:03:38.400 --> 0:03:43.360 I know, but you know, more existentially, my kids are 0:03:43.440 --> 0:03:45.920 growing up. I'm gonna leave home soon, and so yeah, 0:03:45.960 --> 0:03:47.960 I'm valuing every hour I have with them. 0:03:48.240 --> 0:03:51.040 Yeah, they grow up pretty fast, sometimes too fast. 0:03:51.360 --> 0:03:54.720 Do you believe in parental time dilation? Everybody says, oh, 0:03:54.760 --> 0:03:57.080 those years go buy so fast, But you know, when 0:03:57.160 --> 0:03:59.440 you have a screaming toddler and it's two in the morning, 0:03:59.480 --> 0:04:02.360 it feels like about a million hours before they go 0:04:02.520 --> 0:04:03.240 down for their nap. 0:04:04.400 --> 0:04:07.560 Definitely, times needs to go by faster. But I feel 0:04:07.560 --> 0:04:10.800 like I've paid attention pretty good. There's definitely a lot 0:04:10.800 --> 0:04:16.320 of video records of our children, so we always go 0:04:16.360 --> 0:04:17.560 back don memory lean. 0:04:17.880 --> 0:04:19.040 Yeah, that's true. 0:04:19.120 --> 0:04:21.560 But anyways, welcome to our podcast. Daniel and Jorge Explain 0:04:21.600 --> 0:04:24.320 the Universe, a production of iHeartRadio in which. 0:04:24.160 --> 0:04:26.400 We try to take an hour to slow down and 0:04:26.520 --> 0:04:30.640 really understand something. We think it's worthwhile to update the 0:04:30.680 --> 0:04:34.000 mental model in your mind. That's explaining the way the 0:04:34.120 --> 0:04:37.280 universe works out there. We wanted to correspond as much 0:04:37.279 --> 0:04:39.880 as possible, so the way the universe actually works, the 0:04:39.880 --> 0:04:44.480 weird rules that quantum particles follow, the incredible powerful forces 0:04:44.560 --> 0:04:47.840 swirling in the hearts of black holes. We want your 0:04:47.880 --> 0:04:50.279 brain to be aligned with the universe, even if it 0:04:50.320 --> 0:04:51.720 does take a little bit of time. 0:04:52.320 --> 0:04:54.720 Yeah, we do like to take our time to make 0:04:54.720 --> 0:04:57.800 the most of your time when it's time to understand the. 0:04:57.800 --> 0:05:01.239 Universe, and the universe operates on so many amazingly different 0:05:01.360 --> 0:05:04.039 time scales. We think about our lives and you know, 0:05:04.200 --> 0:05:06.919 tens of years, maybe one hundred if we're lucky, but 0:05:07.040 --> 0:05:09.080 that's just the blink of an eye in the history 0:05:09.120 --> 0:05:12.400 of the universe that is billions of years old. And 0:05:12.440 --> 0:05:15.839 then also between every second, there's an incredible number of 0:05:15.960 --> 0:05:19.640 quantum operations happening, electrons buzzing and tuing and throwing, and 0:05:19.680 --> 0:05:23.800 particles appearing and disappearing. Things happen in the universe from 0:05:23.839 --> 0:05:26.320 the tiniest fractions of a second all the way out 0:05:26.400 --> 0:05:29.159 to billions and maybe even trillions of years. 0:05:29.440 --> 0:05:31.240 Yeah, there's a lot going on in the universe, and 0:05:31.320 --> 0:05:34.800 times seems to be underneath it all, dictating at what 0:05:35.000 --> 0:05:37.560 rate things happen and in what order things happen. 0:05:38.160 --> 0:05:40.800 And I wonder sometimes whether the deepest answers to the 0:05:40.880 --> 0:05:44.160 nature of the universe are at the shortest time scales, 0:05:44.320 --> 0:05:47.400 like what is the real fabric of reality, the smallest 0:05:47.400 --> 0:05:50.480 bits in the smallest pieces of time dictating how everything 0:05:50.480 --> 0:05:54.000 else works somehow bubbling up to form our universe, or 0:05:54.040 --> 0:05:57.240 whether the real story is of the longest time periods. 0:05:57.480 --> 0:06:00.080 What's happening to the universe? How does it form or 0:06:00.200 --> 0:06:03.560 what is its future? Over billions or maybe trillions of years? 0:06:03.960 --> 0:06:06.200 You know, the billions of years that our universe has 0:06:06.279 --> 0:06:09.800 existed could just be the first few moments of a 0:06:10.000 --> 0:06:14.039 much longer, impossibly to imagine deep time future. 0:06:15.160 --> 0:06:16.880 Do you feel like maybe you have a little bit 0:06:16.880 --> 0:06:19.960 of a fear of missing out in the universe, you know, 0:06:20.000 --> 0:06:22.120 but maybe things are happening too fast for you to 0:06:22.200 --> 0:06:24.440 notice or too long for you to live through. 0:06:24.680 --> 0:06:27.200 Yeah, I have FOMU. I fear of missing the universe 0:06:27.240 --> 0:06:27.640 for sure. 0:06:28.600 --> 0:06:33.400 Yeah, physical fear of missing the universe. Fomu. 0:06:33.600 --> 0:06:35.640 Yeah. Some of the most interesting things that happened in 0:06:35.680 --> 0:06:39.599 the universe are not the tiniest rules of the little particles, 0:06:39.600 --> 0:06:43.040 but how things come together over time. You know, galaxies 0:06:43.080 --> 0:06:46.279 took hundreds of millions of years to form. Imagine you 0:06:46.320 --> 0:06:49.520 were an intelligent species that existed somehow in the first 0:06:49.600 --> 0:06:51.680 one hundred million years in the universe. You would never 0:06:51.760 --> 0:06:54.200 even see a galaxy, which to us now is like 0:06:54.240 --> 0:06:56.920 the basic building block of what's out there in space. 0:06:57.600 --> 0:06:59.960 What if the most basic building block of the few 0:07:00.000 --> 0:07:04.120 future hasn't yet formed. An intelligent species that evolve in 0:07:04.160 --> 0:07:06.680 a trillion years will wonder about what it was like 0:07:06.760 --> 0:07:09.560 to be us, never even seeing the most basic thing 0:07:09.840 --> 0:07:11.760 that exists in their universe. 0:07:12.360 --> 0:07:14.240 Or even if the future is set at all. 0:07:14.760 --> 0:07:15.200 Yeah. 0:07:15.480 --> 0:07:19.600 Right, they're a big question of whether the universe is deterministic, 0:07:19.720 --> 0:07:22.080 meaning you can sort of know what's going to happen 0:07:22.080 --> 0:07:24.000 in the future or at least in one of the futures, 0:07:24.120 --> 0:07:26.160 or whether it's totally random. 0:07:26.680 --> 0:07:28.960 That's right, And we're hoping to push ourselves into a 0:07:29.000 --> 0:07:32.239 future where we understand the universe a little bit better, 0:07:32.280 --> 0:07:35.280 from the largest time scales to the shortest time scales. 0:07:35.920 --> 0:07:37.680 Yeah, and when it's time to do that, we will 0:07:37.960 --> 0:07:39.720 take a little bit of time to explain it to you, 0:07:39.960 --> 0:07:42.880 in hopefully more or less an hour, because time seems 0:07:42.920 --> 0:07:45.320 to be one of the most fundamental things in the universe, 0:07:45.400 --> 0:07:48.600 but sometimes you have to ask questions about time itself. 0:07:48.760 --> 0:07:51.360 And while we can't see the deep future yet, we 0:07:51.440 --> 0:07:54.000 can do our best to try to understand the shortest 0:07:54.040 --> 0:07:56.920 time scales to zoom in on how fast things are 0:07:56.960 --> 0:07:58.240 happening in the universe. 0:07:58.400 --> 0:08:05.640 So today on the podcast, we'll be tagged clang, what's 0:08:05.720 --> 0:08:08.360 the fastest event ever measured? 0:08:08.600 --> 0:08:11.040 You know, when people run simulations like the Hearts of 0:08:11.120 --> 0:08:14.120 neutron stars or like weather or whatever, they always have 0:08:14.200 --> 0:08:17.480 to choose like a minimum time step. Now you have 0:08:17.600 --> 0:08:20.000 your universe, and then you evolve it forward in time, 0:08:20.080 --> 0:08:22.640 one step in time, and then again and again and again, 0:08:22.920 --> 0:08:26.240 and eventually you describe something longer. But there's that minimum 0:08:26.280 --> 0:08:28.480 time on the computer, right, Yeah, on the computer when 0:08:28.480 --> 0:08:31.520 you run simulations, and so in our real universe. I 0:08:31.520 --> 0:08:33.560 think it's fascinating to think about, like, well, what is 0:08:33.600 --> 0:08:36.480 the shortest time step? How far have we zoomed in 0:08:36.960 --> 0:08:39.559 to see like the fastest thing ever happened? 0:08:39.920 --> 0:08:43.000 Yeah, or possibly we are living in the simulation, right. 0:08:43.120 --> 0:08:45.880 Isn't that something that even smart people think about, not 0:08:46.040 --> 0:08:47.800 just conspiracy theorists. 0:08:48.240 --> 0:08:51.000 I think it's definitely true that smart people think about it. 0:08:51.040 --> 0:08:52.880 I don't know how true it is that smart people 0:08:53.000 --> 0:08:55.640 believe in it or think that it's realistic. I know 0:08:55.640 --> 0:08:57.240 there's a lot of talk out there about it. It's 0:08:57.240 --> 0:08:59.680 a lot of fun to think about. But if you 0:08:59.679 --> 0:09:01.720 have to ask people like whether they really believe it, 0:09:01.760 --> 0:09:04.320 I mean, I think it's unlikely we're living in a simulation. 0:09:04.400 --> 0:09:06.960 For example, you mean it's fun to simulate in your 0:09:07.000 --> 0:09:10.600 head that maybe we're living in a simulation. 0:09:11.360 --> 0:09:14.160 Yeah, it's a really clever sort of meta idea. Like 0:09:14.200 --> 0:09:16.960 we think about simulations. As you say, we run simulations 0:09:17.000 --> 0:09:18.680 in our head. We use simulations for our science. We 0:09:18.679 --> 0:09:21.440 had a whole fun podcast episode about the importance of 0:09:21.480 --> 0:09:25.120 doing simulations in science. It's really a whole new branch 0:09:25.200 --> 0:09:28.480 of science, sort of different from experimental and theoretical physics. 0:09:29.080 --> 0:09:31.719 You know, we describe things like in vivo or in 0:09:31.840 --> 0:09:34.960 vitro and now sometimes we call them in silico. But 0:09:35.040 --> 0:09:37.280 I don't know that we actually are living in a simulation, 0:09:37.520 --> 0:09:39.360 or you know, how we would actually prove that. But 0:09:39.440 --> 0:09:41.640 we have a whole episode about that, so folks interested 0:09:41.679 --> 0:09:44.200 in that go check out that episode right right. 0:09:44.600 --> 0:09:47.079 But whether it's a simulation or not, there's definitely time 0:09:47.200 --> 0:09:49.600 in it. And as you said, when we create little 0:09:49.640 --> 0:09:52.239 universes in our computers, you have to pick a timestep 0:09:53.160 --> 0:09:55.280 to do your simulation, and so you can kind of 0:09:55.280 --> 0:09:58.080 ask the question does that happen in the real universe 0:09:58.120 --> 0:09:58.480 as well? 0:09:58.840 --> 0:10:01.240 Yeah, and when we do it in our simulations, we 0:10:01.360 --> 0:10:05.120 pick a timestep short enough that we're not ignoring anything important. 0:10:05.559 --> 0:10:07.000 So we try to figure out, like, what is the 0:10:07.000 --> 0:10:09.520 shortest time step we're interested in. You know, if you're 0:10:09.559 --> 0:10:12.600 simulating like a evolution of a galaxy, nothing really exciting 0:10:12.679 --> 0:10:14.640 happens in a year or one hundred years, so you 0:10:14.720 --> 0:10:17.800 might take like thousand year time steps. But if you're 0:10:17.800 --> 0:10:21.760 simulating like a nuclear explosion underground, you might take timesteps 0:10:21.760 --> 0:10:23.920 of like a millionth of a second to make sure 0:10:23.960 --> 0:10:25.600 you're capturing all the dynamics. 0:10:25.880 --> 0:10:27.720 Yeah, and as you said, there's lots of things happening 0:10:27.800 --> 0:10:31.240 in the universe, and the idea of a timestep is 0:10:31.280 --> 0:10:34.480 also important when you try to measure things, right. Yeah, Like, 0:10:34.480 --> 0:10:36.160 if you're trying to measure an explosion, you don't want 0:10:36.160 --> 0:10:38.440 to sample the explosion every three minutes because it's going 0:10:38.480 --> 0:10:41.880 to be gone and over. And when you're sampling, you know, 0:10:41.960 --> 0:10:43.320 had the motion of a start, you don't want to 0:10:43.320 --> 0:10:45.480 do it every femtosecond because you're going to have too 0:10:45.559 --> 0:10:46.240 much data. 0:10:46.360 --> 0:10:50.120 Yeah, exactly, So things happen on different timescales, and the 0:10:50.200 --> 0:10:52.959 question is like, what's the fastest thing we've ever measured? 0:10:52.960 --> 0:10:55.960 And what's the actual minimum time slice of the universe? 0:10:57.000 --> 0:11:02.000 Two big questions about very small things. Hopefully we can 0:11:02.040 --> 0:11:03.720 do it in the short amount of time that we 0:11:03.800 --> 0:11:06.680 have well, as usually, we were wondering how many people 0:11:06.679 --> 0:11:08.800 out there had thought about the question of what is 0:11:08.840 --> 0:11:12.440 the fastest event ever measured? So Daniel went out there 0:11:12.480 --> 0:11:15.240 once again to ask people, what do you think is 0:11:15.280 --> 0:11:19.000 the most fleeting or fastest physical event ever measured? 0:11:19.160 --> 0:11:21.480 Thanks very much to our listeners who answer these questions 0:11:21.600 --> 0:11:24.880 very very quickly. I'm very grateful for your contributions. It 0:11:24.920 --> 0:11:28.040 helps me understand what people are thinking about. And I 0:11:28.080 --> 0:11:30.400 hope you enjoy hearing your voice on the air. And 0:11:30.400 --> 0:11:32.400 if you are out there listening and would like to 0:11:32.400 --> 0:11:35.200 hear your voice answering these questions, please don't be shy 0:11:35.280 --> 0:11:38.520 write to me to questions at Danielandjorge dot com. 0:11:38.520 --> 0:11:40.000 So think about it for a second. What do you 0:11:40.040 --> 0:11:44.720 think is the fastest thing humans have ever detected? Here's 0:11:44.720 --> 0:11:45.560 what people had to say. 0:11:46.400 --> 0:11:50.439 I don't know what the smallest time slice ever measured. Here, 0:11:51.120 --> 0:11:56.320 I'm going to assume that it's somehow around themto seconds. 0:11:56.360 --> 0:11:58.040 I don't know why that number sticks my brain, but 0:11:58.040 --> 0:11:59.360 I'm going to say themto seconds. 0:12:00.200 --> 0:12:03.280 The smallest amount of space ever measured, I think is 0:12:03.320 --> 0:12:04.319 the plank space. 0:12:05.880 --> 0:12:07.760 Gonna go with plank time. 0:12:08.240 --> 0:12:11.120 That's easy. It's the time between when butter goes from 0:12:11.200 --> 0:12:15.840 being soft to being soup. But actually it probably tend 0:12:15.920 --> 0:12:19.679 to the negative twenty something, at which point I guess 0:12:20.720 --> 0:12:23.320 doesn't even show that time makes any sense anymore. 0:12:23.880 --> 0:12:25.960 All Right, we got some cooking answers here. 0:12:27.679 --> 0:12:29.760 You know, some people listen to our podcast while they're 0:12:29.800 --> 0:12:32.080 making dinner, and that might have influenced this answer. 0:12:33.200 --> 0:12:36.400 Well, I'm very interested in this recipe that where you 0:12:36.440 --> 0:12:37.400 make soup out of butter. 0:12:38.559 --> 0:12:40.640 You've never had butter soup. Oh man, that. 0:12:43.360 --> 0:12:44.840 Sounds so healthy, so healthy. 0:12:45.400 --> 0:12:49.440 Yeah, I'll have butter soup low fat version please. Yeah. 0:12:49.480 --> 0:12:51.760 That will definitely shorten your time on Earth for sure. 0:12:52.160 --> 0:12:54.640 I mean expand your space, but short in your time. 0:12:55.120 --> 0:12:58.959 I mean that seems like the wrong proportions. 0:12:59.640 --> 0:13:02.280 With well. Buttered chicken is a very popular recipe, so 0:13:02.320 --> 0:13:04.400 I'm sure butter soup is a thing people can make. 0:13:04.600 --> 0:13:09.520 Mm, but buttered chicken soup Oh my goodness, what's better 0:13:09.559 --> 0:13:12.120 than the physics of that? How does it even work? 0:13:13.600 --> 0:13:14.760 It definitely adds mass. 0:13:15.120 --> 0:13:19.040 But yeah, it's definitely an interesting question, and so let's 0:13:19.080 --> 0:13:21.560 jump into it. Daniel. First of all, I guess let's 0:13:21.559 --> 0:13:25.120 talk about time in general and the idea that maybe 0:13:25.160 --> 0:13:28.680 time is pixelated or there's a minimum amount of time 0:13:28.720 --> 0:13:31.439 in the universe. What if physicists think about that. 0:13:31.760 --> 0:13:34.839 Physicists really have no idea how time works. 0:13:34.840 --> 0:13:35.560 All right, we're done. 0:13:35.679 --> 0:13:38.200 Yeah, so it's about time we gave up. 0:13:38.520 --> 0:13:38.600 No. 0:13:38.720 --> 0:13:43.040 Yeah, the shortest episode ever, the shortest podcast about physics 0:13:43.080 --> 0:13:45.120 ever recorded, today's episode. 0:13:45.400 --> 0:13:49.000 Yeah, every podcast is just we don't know. Done. No, 0:13:49.200 --> 0:13:52.040 It is really an enduring mystery. And it's weird because 0:13:52.080 --> 0:13:54.520 time is something we sort of feel like we understand. 0:13:54.520 --> 0:13:56.439 It's part of our everyday lives. We talk about all 0:13:56.440 --> 0:13:59.240 the time. We all have complicated schedules, we rely on time, 0:13:59.280 --> 0:14:02.040 We do time zoneans, we mess them up and miss meetings. 0:14:02.480 --> 0:14:06.240 Time is both familiar and also mysterious because we don't 0:14:06.320 --> 0:14:09.880 understand like what it is. Special relativity tells us that 0:14:09.920 --> 0:14:13.199 it's deeply connected to space, and it makes actually much 0:14:13.200 --> 0:14:16.120 more sense to think about time and space together. As 0:14:16.200 --> 0:14:20.080 one unit space time. And that makes sense because some 0:14:20.200 --> 0:14:22.920 of the things in special relativity show us that space 0:14:22.960 --> 0:14:26.160 and time are mixed. That you know, moving quickly through 0:14:26.200 --> 0:14:29.120 space can affect your measurement of time. All these sorts 0:14:29.120 --> 0:14:31.280 of things sort of the same way that like electricity 0:14:31.320 --> 0:14:35.120 and magnetism make more sense when stuck together into one idea. 0:14:35.560 --> 0:14:37.960 It doesn't tell you that electricity and magnetism are the 0:14:37.960 --> 0:14:40.120 same thing, just that they're connected in the same way 0:14:40.400 --> 0:14:43.320 space and time are connected. They're not the same, but 0:14:43.360 --> 0:14:46.920 they're related to each other in special relativity. 0:14:46.840 --> 0:14:49.520 Right because I guess we grow up, you know, not 0:14:49.720 --> 0:14:52.160 just as kids, but also like sort of through elementary 0:14:52.240 --> 0:14:54.800 high school, thinking that space and time are sort of immovable, 0:14:54.880 --> 0:14:57.600 right like fixed in the universe. But really then eventually 0:14:57.680 --> 0:15:00.040 you learn that space is and time are both and 0:15:00.160 --> 0:15:04.160 a squishy, right envirorable. Time can slow down, time can 0:15:04.200 --> 0:15:07.400 speed up, space can contract, space can expand they can 0:15:07.440 --> 0:15:10.600 both wiggle. But where did this idea that maybe time 0:15:10.680 --> 0:15:13.080 is pixelated? Where did it come from or what would 0:15:13.160 --> 0:15:15.000 make physicists think that it might be? 0:15:15.280 --> 0:15:19.320 Yeah, it's fascinating. You sort of trace the evolution of 0:15:19.360 --> 0:15:21.960 the ideas and we all sort of have that same experience. 0:15:22.080 --> 0:15:24.760 Like Newton thought of space and time as absolute and fixed, 0:15:24.760 --> 0:15:28.000 as you say, sort of immutable. They're like the backdrop 0:15:28.080 --> 0:15:31.920 of the universe. But then Einstein showd us that they're not. Actually, 0:15:32.160 --> 0:15:37.160 they're flexible, they're interconnected. But most importantly, Einstein's theory of 0:15:37.240 --> 0:15:42.560 general relativity and special relativity still suggests that time is continuous, 0:15:42.720 --> 0:15:48.120 it's smooth, it's infinitely divisible, that it's not discrete or pixelated. 0:15:48.200 --> 0:15:50.960 It's not like there are steps in time. In Einstein's 0:15:51.000 --> 0:15:53.880 theory of the universe. You can take any two moments 0:15:53.920 --> 0:15:56.960 and there's always another moment in between. Right, there's no 0:15:57.160 --> 0:16:01.080 minimum time step in Einstein's universe, and relativity describes the 0:16:01.160 --> 0:16:04.480 universe very very well. It describes the expansion of the 0:16:04.560 --> 0:16:08.240 universe and the motion of galaxies and everything we've ever 0:16:08.280 --> 0:16:10.920 been able to test about general relativity has always been 0:16:11.000 --> 0:16:14.160 bang on, exactly correct, with astonishing accuracy. 0:16:14.720 --> 0:16:17.560 Now, when you say the answing theories suggest that what 0:16:17.600 --> 0:16:19.400 does that mean? Does that mean that it only works 0:16:19.440 --> 0:16:22.880 with continuous time or that is just always used continuous 0:16:22.880 --> 0:16:26.320 time and nobody has thought about applying it to the 0:16:26.720 --> 0:16:27.560 pixelated time. 0:16:28.400 --> 0:16:32.600 Yeah, great question. It works assuming that space is continuous. 0:16:32.600 --> 0:16:34.760 So you're like, let's start from that assumption and then 0:16:34.800 --> 0:16:37.160 build on top of that. And then you could ask, well, 0:16:37.200 --> 0:16:39.800 could you have a different theory that didn't make that assumption. 0:16:39.880 --> 0:16:43.680 What if you assumed instead that space was pixelated? And 0:16:43.760 --> 0:16:45.760 then you run into all sorts of mathematical problems that 0:16:45.800 --> 0:16:48.800 nobody has been able to solve before. The motivation for 0:16:48.840 --> 0:16:51.280 that comes from quantum mechanics. Like you might ask, well, 0:16:51.320 --> 0:16:53.840 why would you wake time pixelated? It feels pretty smooth 0:16:53.880 --> 0:16:55.440 to me. I mean, we measure it in seconds, but 0:16:55.480 --> 0:16:58.560 we know there's always milliseconds below those and microseconds below those. 0:16:58.960 --> 0:17:01.520 Why would you ever imagine there would be pixels? And 0:17:01.560 --> 0:17:04.320 that comes from the idea of quantum mechanics, which tells 0:17:04.440 --> 0:17:07.680 us that the nature of reality is a sort of discrete. 0:17:07.720 --> 0:17:10.919 It's like made out of chunks. It's not smooth, you know, 0:17:11.000 --> 0:17:12.680 like when we look at a beam of life from 0:17:12.680 --> 0:17:17.000 a flashlight. Einstein's actual discovery from the photoelectric effect tells 0:17:17.080 --> 0:17:19.600 us that it's not just like smooth beams of light 0:17:19.640 --> 0:17:22.480 that you could like chop up infinitely small, that there's 0:17:22.520 --> 0:17:25.639 like a minimum brightness because light comes in packets, these 0:17:25.680 --> 0:17:30.159 little things called photons, right, and so quantum mechanics suggests 0:17:30.200 --> 0:17:33.600 that even though the universe seems continuous and smooth when 0:17:33.680 --> 0:17:36.120 you zoom in, it really is kind of pixelated. It's 0:17:36.119 --> 0:17:38.200 just like when you look at your computer screen and 0:17:38.280 --> 0:17:41.640 you zoom in, it seems smooth, right, but actually there's 0:17:41.680 --> 0:17:43.760 little dots there. There are little basic units. 0:17:44.200 --> 0:17:48.600 So that's the motivation, right, Like even this podcast is pixelated, right, 0:17:48.680 --> 0:17:52.199 Like we're recording into a digital device. It's recording it 0:17:52.520 --> 0:17:54.960 with a time sample with a minimum time sampling rate, 0:17:55.080 --> 0:17:58.720 and then it gets transmitted as bits and then it 0:17:58.760 --> 0:18:01.160 plays out there where you're listening to this as those 0:18:01.359 --> 0:18:02.439 little bits. 0:18:02.720 --> 0:18:07.680 Yeah, you're exactly right. Digitization is creating some pixelization, right, 0:18:07.720 --> 0:18:10.600 You're creating these units, and exactly the sort of way 0:18:10.640 --> 0:18:15.160 quantum mechanics works. Fascinatingly though, even analog measurements have a resolution, right, 0:18:15.200 --> 0:18:17.919 like a photograph. You think of it as like, oh, 0:18:17.920 --> 0:18:21.240 it's photons. It's not like pixels like a digital camera 0:18:21.800 --> 0:18:25.880 or a analog recording on like vinyl or on a tape. 0:18:26.000 --> 0:18:28.520 It's not using digits. It's analog. It's using some sort 0:18:28.520 --> 0:18:31.160 of like magnetic technology to record it, or like physical 0:18:31.200 --> 0:18:34.800 bumps on the vinyl. Still that is discrete, right, because 0:18:34.960 --> 0:18:38.000 in the end, there's a finite resolution, Like for photographs 0:18:38.160 --> 0:18:41.399 there's a resolution of a photon or the molecule of 0:18:41.480 --> 0:18:44.600 the chemical atoms that are you know, recording the light, 0:18:45.359 --> 0:18:47.720 or on the tape, there's still the resolution of like 0:18:47.720 --> 0:18:50.520 the little magnets that are aligned to record your information, 0:18:50.760 --> 0:18:52.879 or on the vinyl there's still like the chemistry of 0:18:52.920 --> 0:18:56.280 the vinyl itself. So analog is higher resolution, but it's 0:18:56.280 --> 0:18:59.320 not infinite resolution, right, And so. 0:18:59.280 --> 0:19:02.359 The idea is that maybe time is also pixelated. 0:19:02.080 --> 0:19:04.560 Yeah, because it's weird to think about time as infinite. 0:19:04.600 --> 0:19:08.320 You know, we don't see infinities in reality. Everywhere we 0:19:08.359 --> 0:19:11.919 see infinities in our theory, always something acts to prevent 0:19:11.920 --> 0:19:14.480 it from happening in reality. And this is what quantum 0:19:14.520 --> 0:19:17.320 mechanics tells us, that there are new infinities. You can't 0:19:17.320 --> 0:19:22.320 divide things infinitely small, and maybe space itself and time 0:19:22.560 --> 0:19:26.359 are pixelated. Maybe there's a minimum unit of space and 0:19:26.400 --> 0:19:29.600 a minimum unit of time. This would be very natural 0:19:29.600 --> 0:19:32.800 from a quantum mechanical point of view. You asked earlier, like, well, 0:19:32.840 --> 0:19:35.280 has anybody tried that? What if you built general relativity 0:19:35.520 --> 0:19:38.080 out of discrete units of space and time, you know, 0:19:38.160 --> 0:19:40.360 pixelated the universe, and people are trying to do that. 0:19:40.440 --> 0:19:43.439 But bringing together the ideas of general relativity and the 0:19:43.440 --> 0:19:46.439 ideas of quantum mechanics to make that new concept, like 0:19:46.480 --> 0:19:48.760 a theory of gravity and space and time that's built 0:19:48.760 --> 0:19:51.560 on discrete units has so far not been successful. People 0:19:51.600 --> 0:19:53.960 have been trying for decades. You run into all sorts 0:19:53.960 --> 0:19:57.000 of mathematical problems doing so. So we don't have a 0:19:57.119 --> 0:20:00.320 theory of general relativity that's built on discrete time. So 0:20:00.359 --> 0:20:02.399 we have this theory of general relativity. It tells us 0:20:02.440 --> 0:20:05.680 about space and gravity but assumes continuous time. And then 0:20:05.680 --> 0:20:08.920 this idea that the universe is quantum mechanical and time 0:20:08.960 --> 0:20:11.480 and space are probably discrete. But we can't bring these 0:20:11.520 --> 0:20:12.200