WEBVTT - Is time pixelated? 0:00:01.280 --> 0:00:03.440 Hey, Jorhan Daniel here, and we want to tell you 0:00:03.480 --> 0:00:07.280 about our new book. It's called Frequently Asked Questions about 0:00:07.320 --> 0:00:09.879 the Universe because you have questions about the universe, and 0:00:09.960 --> 0:00:12.360 so we decided to write a book all about them. 0:00:12.440 --> 0:00:14.800 We talk about your questions, we give some answers, we 0:00:14.880 --> 0:00:17.560 make a bunch of silly jokes as usual, and we 0:00:17.600 --> 0:00:20.159 tackle all kinds of questions, including what happens if I 0:00:20.200 --> 0:00:22.880 fall into a black hole? Or is there another version 0:00:22.920 --> 0:00:25.480 of you out there that's right? 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Hey Daniel, I have a question 0:01:09.360 --> 0:01:12.240 for you about time? All right? I got time for that, 0:01:12.400 --> 0:01:14.240 all right. So you do a lot of things, right, 0:01:14.319 --> 0:01:17.119 you're a professor, you have a podcast, and you're always 0:01:17.160 --> 0:01:20.319 switching between them. That's true. It's a lot of different 0:01:20.319 --> 0:01:22.520 things to manage, all right. So then what do you 0:01:22.560 --> 0:01:27.319 think is the shortest useful unit of time? Like, can 0:01:27.319 --> 0:01:30.080 you get something done in five minutes? Or do you 0:01:30.080 --> 0:01:32.640 need like an hour just to dig into something? Well, 0:01:32.680 --> 0:01:34.760 you know, sort of depends on what it is. Is 0:01:34.800 --> 0:01:38.000 it serious research or just like writing bad jokes for 0:01:38.000 --> 0:01:41.640 the podcast? What do you mean? All right? Well, which 0:01:41.640 --> 0:01:44.399 one takes more time? Oh? Bad jokes for sure? I 0:01:44.400 --> 0:01:46.880 mean at some point you just can't scrape that barrel 0:01:46.920 --> 0:01:48.720 any deeper. What if you just give you more time? 0:01:48.720 --> 0:01:50.840 As long as you're writing jokes about time, they basically 0:01:50.880 --> 0:02:08.720 just right themselves. Hi, I'm Jorge. I'm a cartoonist and 0:02:08.760 --> 0:02:11.920 the creator of PhD comics. I'm Daniel. I'm a particle 0:02:11.960 --> 0:02:15.160 physicist and a professor, and I never seem to have 0:02:15.320 --> 0:02:17.960 enough time. Really, can't you just make time in your 0:02:18.040 --> 0:02:21.240 particle collider? I mean, right, it's called space time. Can 0:02:21.320 --> 0:02:24.280 you just transform some space into time? You know? What 0:02:24.320 --> 0:02:26.680 I need to do is to speed up the rest 0:02:26.720 --> 0:02:28.560 of the world near the speed of light, so it 0:02:28.680 --> 0:02:30.960 runs slowly, and then I can just get all my 0:02:31.040 --> 0:02:33.760 work done while everybody else is frozen. Oh that's a 0:02:33.760 --> 0:02:35.920 good idea. But then you'd be left behind. Everyone would 0:02:35.919 --> 0:02:39.000 be really far away, you'd be light years away, but 0:02:39.040 --> 0:02:41.760 you would catch up and work. I would made all 0:02:41.800 --> 0:02:45.119 my deadlines even though I'd be in the neighboring star system. Yeah, 0:02:45.160 --> 0:02:46.920 there you go. And then how do you turn your 0:02:46.919 --> 0:02:51.120 work in? You can't. I knew there was a flaw 0:02:51.160 --> 0:02:55.600 on this plan. Yeah, you paradox yourself into unemployment. The 0:02:55.639 --> 0:02:58.760 twin professor paradox. But welcome to our podcast. Daniel and 0:02:58.840 --> 0:03:01.560 Jorge explained the Universe say production of I Heart Radio, 0:03:01.639 --> 0:03:04.880 in which we take that mental journey around the universe, 0:03:05.080 --> 0:03:08.040 speeding your brain up to near the speed of light, 0:03:08.320 --> 0:03:11.040 so that we can try to understand the very nature 0:03:11.120 --> 0:03:14.359 of the universe that we find ourselves in, this incredible, 0:03:14.400 --> 0:03:18.200 glittering cosmos with all of its wonderful questions that it inspires, 0:03:18.280 --> 0:03:20.280 the things that make us go, huh, why is it 0:03:20.360 --> 0:03:22.919 like that? Why couldn't it be like this other thing? 0:03:23.200 --> 0:03:25.960 We dig into all of that on this podcast. We 0:03:26.040 --> 0:03:28.639 stare right into the abyss of our ignorance, and we 0:03:28.720 --> 0:03:31.560 ask why, and we do our best to explain what 0:03:31.600 --> 0:03:34.200 we do and don't know to you. Yeah, because it 0:03:34.320 --> 0:03:37.040 is a pretty wonderful universe, but it's also kind of 0:03:37.040 --> 0:03:40.160 a weird universe. We grow up thinking that space is 0:03:40.240 --> 0:03:43.119 fixed and firm and never changes, but actually it sort 0:03:43.120 --> 0:03:46.800 of does. It's it's squishy and also kind of ripley. 0:03:46.840 --> 0:03:49.120 I'm glad it's a weird universe, though, What would it 0:03:49.120 --> 0:03:52.119 be like if we were doing physics and discovering Yeah, 0:03:52.200 --> 0:03:54.880 the universe is basically exactly as you thought it was 0:03:55.040 --> 0:03:57.640 and kind of boring. After all, you would have to 0:03:57.640 --> 0:04:02.840 switch careers to just writing joke. I don't think I 0:04:02.880 --> 0:04:05.440 could have that as a career. But I wonder sometimes 0:04:05.440 --> 0:04:08.280 about how, you know, we find the universe beautiful, We 0:04:08.320 --> 0:04:12.119 find nature beautiful, and we also find it mysterious and interesting, 0:04:12.360 --> 0:04:15.040 And I wonder if that's an accident or a product 0:04:15.120 --> 0:04:17.039 of the way the human mind works, that we just 0:04:17.160 --> 0:04:20.600 find beauty and mystery everywhere around us. Yeah, or even 0:04:20.600 --> 0:04:24.160 like the word weird, like why is it weird to us? Right? Like? 0:04:24.520 --> 0:04:27.440 What makes us the overall judges of what is weird, 0:04:27.440 --> 0:04:29.920 and what is not? Like, maybe the universe is offended 0:04:29.960 --> 0:04:32.240 by us calling it weird. Yeah, and then the word 0:04:32.320 --> 0:04:34.560 weird itself is weird? Mean you say it enough times, 0:04:34.600 --> 0:04:36.640 it sounds pretty weird. It's got an E and I 0:04:36.800 --> 0:04:40.320 in it, like weird, weird, weird, it's a pretty weird word. Yeah. Yeah, 0:04:40.360 --> 0:04:44.400 but that's the English people's fault. Blame it on the Brits. 0:04:44.560 --> 0:04:46.960 So yeah, it is a pretty, let's say, interesting universe. 0:04:47.040 --> 0:04:49.120 You think the universe would be offended if we called 0:04:49.160 --> 0:04:52.560 it interesting, sort of like living in interesting times. No, 0:04:52.720 --> 0:04:54.520 I think it's good. I think we are lucky. It's 0:04:54.520 --> 0:04:56.640 one of the things that makes life worth living. You know. 0:04:56.680 --> 0:04:59.200 People sometimes ask me this question, like why should we 0:04:59.240 --> 0:05:02.320 fund particle physics? What good is it? And I hear 0:05:02.320 --> 0:05:04.960 my colleagues making arguments like, well, you know, we might 0:05:05.000 --> 0:05:08.000 have spinoff technologies or we invented the Worldwide Web. But 0:05:08.080 --> 0:05:11.040 for me, the true answer is that it explores the universe. 0:05:11.080 --> 0:05:13.800 It explores the nature of the human existence, sort of 0:05:13.839 --> 0:05:16.920 the same way like art does you ask an artist like, 0:05:16.920 --> 0:05:18.919 and why should we pay for art? Why should people 0:05:18.920 --> 0:05:21.080 write books? Well, it's you know, just part of the 0:05:21.200 --> 0:05:24.159 joy of life. Is unraveling the mystery of the universe 0:05:24.200 --> 0:05:27.120 we find ourselves in. That's it, and that's enough. Well, 0:05:27.160 --> 0:05:28.599 I'm not sure you want to be in the same 0:05:28.600 --> 0:05:31.000 position that the arts are in trying to get funding 0:05:31.279 --> 0:05:34.760 using that argument, So I would stick with the Worldwide 0:05:34.760 --> 0:05:37.719 Web and useful technology for now. To be honest, I 0:05:37.720 --> 0:05:39.760 think you just haven't asked big enough, Like why don't 0:05:39.800 --> 0:05:42.839 you pitch your ten billion dollar cartoon to the government. 0:05:42.920 --> 0:05:44.920 You know, the more you ask for, the more you get. 0:05:45.000 --> 0:05:47.720 I'm not sure the time is right for that crazy idea, 0:05:48.040 --> 0:05:50.760 the large hay drawing cartoon. Yeah, there you go. It 0:05:50.800 --> 0:05:53.840 will break open the universe probably and create imaginary black 0:05:53.839 --> 0:05:56.360 holes of ink that will swallow up the Earth. That's right, 0:05:56.440 --> 0:05:58.680 that sounds good. I'd read that my pitching my tax 0:05:58.720 --> 0:06:01.599 dollars for that. Anyway, we love for the universe is mysterious, 0:06:01.600 --> 0:06:05.320 and it presents us with really fun, interesting, basic questions, 0:06:05.400 --> 0:06:08.200 things that we don't understand about, you know, the very 0:06:08.279 --> 0:06:11.479 like ABC's of reality. Yeah, because I guess you know, 0:06:11.640 --> 0:06:14.560 we grow up experiencing the universe in one way and 0:06:14.600 --> 0:06:16.600 we think it works in a certain way in our brains. 0:06:16.640 --> 0:06:18.760 But really, when you sort of drill down into it, 0:06:18.920 --> 0:06:21.560 or you scale up to bigger things. There are big 0:06:21.600 --> 0:06:24.280 surprises and it doesn't work the way we think it does. Yeah, 0:06:24.320 --> 0:06:26.400 I think of the universe is sort of like a ladder. 0:06:26.520 --> 0:06:29.040 You know, if you look at it at one distance 0:06:29.080 --> 0:06:31.640 scale and one time scale, it works a certain way. 0:06:31.680 --> 0:06:34.680 If you look at another distance scale, like if you're 0:06:34.720 --> 0:06:37.600 looking at particles or if you're looking at water droplets 0:06:37.720 --> 0:06:41.040 or galaxies, there seem to be different rules that apply 0:06:41.360 --> 0:06:44.280 at these different distance scales, and that's fascinating. It makes 0:06:44.279 --> 0:06:46.520 you wonder, like, are any of these fundamental Are we 0:06:46.640 --> 0:06:49.560 learning anything really deep and true about the universe? Or 0:06:49.560 --> 0:06:51.640 does it all just depends on the questions you're asking? 0:06:51.960 --> 0:06:54.240 And so it's not just scientists who have questions about 0:06:54.240 --> 0:06:56.560 the universe and about the nature of the universe. It's 0:06:56.640 --> 0:06:59.960 also our listeners and everyday people just like you. That's right, 0:07:00.000 --> 0:07:03.919 because remember that science is just people asking questions, and 0:07:03.960 --> 0:07:07.600 the investigations we do are motivated by the individual questions 0:07:07.640 --> 0:07:11.280 of individual scientists wondering things about the universe, and that 0:07:11.360 --> 0:07:14.480 includes you, because we are all out there wondering about 0:07:14.480 --> 0:07:17.240 the universe and trying to figure it out. So today 0:07:17.280 --> 0:07:19.520 we are tackling a question that we got from a 0:07:19.640 --> 0:07:23.680 listener who comes from Sweden. It's Henrik, and Henrik is 0:07:23.720 --> 0:07:27.800 a pretty interesting question about time. So here is Henrick's question. Hi, 0:07:29.080 --> 0:07:32.520 I'm Henrik from Sweden and I have been wondering if 0:07:32.760 --> 0:07:37.080 time could be pixelated? Is there any minimum unit of time? 0:07:37.480 --> 0:07:41.320 Or could it be infinitely short? And when I listened 0:07:41.360 --> 0:07:44.920 to your episode about space being pixelated or not, I 0:07:45.000 --> 0:07:49.080 started wondering if time could be pixelated while space isn't, 0:07:49.440 --> 0:07:52.880 or vice versa. Thank you guys. All right, it's a 0:07:52.920 --> 0:07:55.480 pretty interesting question from Henry. So today on the podcast 0:07:55.520 --> 0:08:05.720 will be tackling is time pixelated? That's a pretty strange question, 0:08:05.880 --> 0:08:10.160 Is time pixelated? I don't usually associate pixels with time. Yeah, 0:08:10.200 --> 0:08:14.520 it's a wonderful question, and I love hearing Henrik do physics. 0:08:14.560 --> 0:08:16.920 You know, he is absorbing what we're talking about and 0:08:17.000 --> 0:08:19.920 he's taking it to the next natural consequence. And that's 0:08:19.960 --> 0:08:21.320 what you got to do with the theory. You say, 0:08:21.360 --> 0:08:23.920 all right, well, this describes what I'm thinking about or 0:08:23.960 --> 0:08:26.920 describes what I've seen. Can I extrapolate from it to 0:08:26.960 --> 0:08:29.520 the rest of the universe or what are the consequences 0:08:29.560 --> 0:08:31.960 of it? How can I test and explore this? So 0:08:32.000 --> 0:08:34.920 that's exactly doing physics. So kudos to you, Henrick, for 0:08:35.200 --> 0:08:37.600 doing some physics in your mind. Yeah, Daniel will be 0:08:37.600 --> 0:08:40.280 sending you a check in the mill right now, right 0:08:40.280 --> 0:08:43.440 after this podcast. I'm gonna email you some Swedish fish, 0:08:43.559 --> 0:08:45.559 my favorite Swedish candy. All right. So then it's a 0:08:45.559 --> 0:08:48.080 pretty interesting question. And Henrick was saying that he listened 0:08:48.120 --> 0:08:50.200 to an episode that we had about whether or not 0:08:50.320 --> 0:08:53.480 space is pixelated. So there's this idea that space could 0:08:53.480 --> 0:08:57.240 be pixelated, meaning like it's not smooth and continuous, maybe 0:08:57.240 --> 0:09:00.280 it's like a grid or something, or it's disc rate 0:09:00.360 --> 0:09:03.439 at the very smallest level. And his question is whether 0:09:03.559 --> 0:09:06.000 or not it applies to time as well. That's right, 0:09:06.040 --> 0:09:08.320 because we often talk on the podcast about how space 0:09:08.360 --> 0:09:11.800 and time are related, and then in relativity at least 0:09:11.840 --> 0:09:15.200 we see them as parts of space time a four 0:09:15.280 --> 0:09:18.640 dimensional object. So it's a very natural question. Yeah, and 0:09:18.679 --> 0:09:20.880 so what did we conclude in that podcast episode about 0:09:20.920 --> 0:09:23.840 space being pixelated? We concluded that we don't know, and 0:09:23.920 --> 0:09:26.840 we might never know, but there are good reasons to 0:09:26.920 --> 0:09:29.920 think that space might be pixelated, right, due to like 0:09:30.000 --> 0:09:33.680 quantum physics and they're being like a theoretical plank scale 0:09:33.720 --> 0:09:36.280 to the universe as well. Right, exactly, we don't know 0:09:36.400 --> 0:09:39.520 how small the pixels of space are if they exist, 0:09:39.559 --> 0:09:41.960 and we have a very simple, kind of bad estimate 0:09:42.000 --> 0:09:45.520 for how small they might be, just by multiplying constants 0:09:45.559 --> 0:09:48.199 of the universe together. And it's very very small number, 0:09:48.360 --> 0:09:52.040 like ten to the minus thirty five meters. That's not 0:09:52.080 --> 0:09:54.640 a measurement of how small the space pixels are or 0:09:54.720 --> 0:09:57.480 proof that space pixels exist. But if you have no 0:09:57.679 --> 0:10:00.480 other information about how to estimate it, this is all 0:10:00.559 --> 0:10:02.040 you can do. It gives you a sense for like 0:10:02.280 --> 0:10:04.760 what the neighborhood of the size might be, all right, 0:10:04.840 --> 0:10:06.600 So then if you're curious, you can look up that 0:10:06.679 --> 0:10:10.160 episode in our archive. But today we're talking about time 0:10:10.160 --> 0:10:12.800 and whether it's pixelated, and so, as usually, we were 0:10:12.800 --> 0:10:14.880 wondering how many people out there have thought about this 0:10:15.000 --> 0:10:17.480 question or had had time to think about this question 0:10:17.840 --> 0:10:20.520 at least a pixel of time and maybe had an 0:10:20.520 --> 0:10:22.600 answer for it. So Daniel went out there into the 0:10:22.640 --> 0:10:26.640 internet to ask listeners is time pixelated? And so if 0:10:26.640 --> 0:10:30.400 you have time to donate your thoughts on random physics 0:10:30.480 --> 0:10:34.000 questions for future podcast episodes. Please don't be shy, right 0:10:34.040 --> 0:10:36.960 to me. Two questions at Daniel and Jorge dot com. 0:10:37.040 --> 0:10:38.520 So think about it for a second. Do you think 0:10:38.559 --> 0:10:41.800 there is a minimum amount of time in the universe? 0:10:42.400 --> 0:10:44.240 Here's what people had to say. I guess if you 0:10:44.360 --> 0:10:49.840 zoomed in far enough, time might be pixelated, like if 0:10:49.880 --> 0:10:52.840 you imagined it as a film strip, if you zoomed 0:10:52.880 --> 0:10:58.559 in just millions and millions and millions of times, that 0:10:59.080 --> 0:11:02.440 it would beam moving sort of in frames, as if 0:11:02.440 --> 0:11:06.240 like a movie kind of thing. Tom, pixelation, haven't heard 0:11:06.280 --> 0:11:10.920 of it? Um, tell me about it. Sounds crazy, Yes, 0:11:14.280 --> 0:11:17.480 it's a usual thing. So do you think it's pixelated 0:11:17.559 --> 0:11:26.960 or continuous? Okay, it's continuous? Okay? Wow? Man, I don't 0:11:26.960 --> 0:11:29.000 even know how to wrap my head around this question. 0:11:29.120 --> 0:11:33.319 Is time pixelated? What does that even mean? Is it 0:11:33.440 --> 0:11:35.480 just like if a second is a pixel or even 0:11:35.600 --> 0:11:38.720 nano second is a pixel. I have no idea how 0:11:38.760 --> 0:11:41.200 to answer this question. I really don't know what that 0:11:41.280 --> 0:11:49.439 question means. Maybe like, is is time quantized in some form? Honest? 0:11:49.480 --> 0:11:53.560 I have no idea time. It's very strange. A lot 0:11:53.600 --> 0:11:57.400 we don't know. I'm not sure. I think that there 0:11:57.400 --> 0:12:00.080 are some theories that suggest it might be, but I 0:12:00.120 --> 0:12:04.080 don't know that we've measured that definitively. My understanding of 0:12:04.120 --> 0:12:07.839 the measuring of time is that it's not infinitely divisible, 0:12:08.920 --> 0:12:15.200 that it is hypothesized that ultimately you'll get two units 0:12:15.200 --> 0:12:18.320 of time that are so short you can't get any short. 0:12:18.360 --> 0:12:23.160 And I think it's referred to as plunk time pixilated 0:12:23.320 --> 0:12:31.199 like all the video games. I'm not sure about. The 0:12:31.360 --> 0:12:36.280 term doesn't seem right. I'm probably not. I have no 0:12:36.360 --> 0:12:41.520 idea from a physics standpoint, but from a perception standpoint, 0:12:42.200 --> 0:12:46.160 I feel like it is um and I think deja 0:12:46.240 --> 0:12:49.800 vu has something to do with that. It's like it 0:12:49.960 --> 0:12:54.080 arrives into my brain in little packets and then my 0:12:54.160 --> 0:12:57.920 brain goes and smooths it all out after the fact, 0:12:58.440 --> 0:13:01.720 so that it in my memories it seems like it's 0:13:01.760 --> 0:13:05.160 all smooth, and I can't actually sense what's going on 0:13:05.240 --> 0:13:08.640 in real time. I have no idea what that means. 0:13:09.360 --> 0:13:14.720 I guess not because I think it's continuous with the 0:13:14.760 --> 0:13:19.320 way that Madam moves in space. All right. Not a 0:13:19.360 --> 0:13:22.360 lot of ideas here. Maybe people didn't spend enough time 0:13:22.480 --> 0:13:24.920 thinking about it. They only thought one or two units 0:13:25.000 --> 0:13:26.680 of time on this and they should have at least 0:13:26.720 --> 0:13:29.280 been ten or two. Yeah, it's a tough question. It 0:13:29.320 --> 0:13:31.840 seems to have puzzled people. Most people just throw their 0:13:31.840 --> 0:13:33.640 hands up in the air and said, I don't know. Yeah, 0:13:33.720 --> 0:13:36.440 it seems a little bit more foreign to people than 0:13:36.520 --> 0:13:39.720 the idea that space is pixelated, like you're familiar with 0:13:39.800 --> 0:13:43.320 looking at a screen, the idea of locations being a 0:13:43.320 --> 0:13:46.320 grid that makes some sense. But the idea of time 0:13:46.360 --> 0:13:49.840 being pixelated, that you know that there are discrete units 0:13:49.920 --> 0:13:53.040 of time as we move forward, that we're stepping forward 0:13:53.080 --> 0:13:55.840 instead of sliding forward, that seems to be a little 0:13:55.880 --> 0:13:59.160 bit more alien. Yeah, so let's maybe tackle this one 0:14:00.040 --> 0:14:01.800 kind of idea at a time. So, first of all, 0:14:01.800 --> 0:14:04.480 what would it mean for time to be pixelated? Would 0:14:04.480 --> 0:14:06.000 it mean like you can cut up time or you 0:14:06.040 --> 0:14:09.320 can step through time in small increments, but at some 0:14:09.400 --> 0:14:12.640 point there comes a point where you can take smaller 0:14:12.679 --> 0:14:16.520 steps in time. There's sort of two very different but 0:14:16.679 --> 0:14:20.520 closely related ways for time to be discreet, for there 0:14:20.520 --> 0:14:23.720 to be like a minimal, sensible unit of time. The 0:14:23.760 --> 0:14:26.400 first is what you were just talking about. This idea 0:14:26.440 --> 0:14:30.360 of pixelization, and pixelization is something we think about for space, right, 0:14:30.440 --> 0:14:33.760 like pixels on the screen. You can either be at 0:14:33.960 --> 0:14:36.720 x equals seven or x equals eight, but you can't 0:14:36.720 --> 0:14:39.320 be at x equals seven and a half. So that's 0:14:39.400 --> 0:14:43.280 very natural sense for space and for time. The idea 0:14:43.320 --> 0:14:47.000 would be that things step forwards in time, that you 0:14:47.000 --> 0:14:50.040 could be like time equals one point seven or time 0:14:50.040 --> 0:14:52.920 equals one point eight, but there is no time equals 0:14:52.920 --> 0:14:55.400 one point seven and a half. That the universe just 0:14:55.440 --> 0:14:58.480 goes from one point seven boom to one point eight. 0:14:58.560 --> 0:15:01.000 It's like ticks on a clock, but there's no moment 0:15:01.080 --> 0:15:03.760 in between the ticks, Like you can't have a half 0:15:03.800 --> 0:15:06.440 of a second or something like that. Yeah, and you know, 0:15:06.440 --> 0:15:09.160 obviously seconds aren't the minimum immunity of time. You can't 0:15:09.200 --> 0:15:11.720 have half of a second. If time units exist, but 0:15:11.720 --> 0:15:14.320 there's a minimum discrete chunk of time, it would be 0:15:14.400 --> 0:15:18.120 super duper small. So that to us it seems continuous, right, 0:15:18.200 --> 0:15:20.840 and you think it doesn't exist or like what happens 0:15:21.120 --> 0:15:24.080 in between those two times? Yeah, well what does it 0:15:24.160 --> 0:15:27.400 mean for the universe to be in between those times? 0:15:27.840 --> 0:15:30.720 It's like it doesn't have a meaning, Like time is 0:15:31.040 --> 0:15:34.400 here and time is there, but in between there isn't anything. 0:15:34.560 --> 0:15:36.480 It just doesn't exist. This is something that's sort of 0:15:36.480 --> 0:15:41.200 familiar to us from learning quantum mechanics, that not everything 0:15:41.280 --> 0:15:44.520 has like a smooth classical path, you know, like an electron. 0:15:44.560 --> 0:15:47.200 You measure it here and then you later you measure 0:15:47.240 --> 0:15:49.840 it over there. Does that mean that it went from 0:15:49.880 --> 0:15:52.440 here to there? No, it just means it was here 0:15:52.680 --> 0:15:54.880 and then it was there. It doesn't have to have 0:15:54.960 --> 0:15:59.360 a location in between. We think of everything as smooth 0:15:59.360 --> 0:16:01.560 and continuous because that's the way it seems to us, 0:16:01.640 --> 0:16:05.120 because we're kind of big and slow. But the universe, 0:16:05.160 --> 0:16:07.960 as you were saying earlier, could be drastically different from 0:16:07.960 --> 0:16:10.040 the way we experience it, all right, So that's one 0:16:10.080 --> 0:16:14.520 possibility that time just doesn't exist in between time pixels, 0:16:14.520 --> 0:16:17.080 like there's a grade of the time in the universe. 0:16:17.160 --> 0:16:19.480 And that's actually something that makes sense to us sort 0:16:19.480 --> 0:16:23.360 of numerically, like when we simulate things in the computer. 0:16:23.600 --> 0:16:26.120 You want to describe, for example, how a hurricane moves 0:16:26.280 --> 0:16:28.960 or how galaxies form, and we want to simulate them. 0:16:29.080 --> 0:16:31.320 That's exactly how we do it. We make a grid 0:16:31.360 --> 0:16:35.080 in time, and we step our simulated universe forward. We say, 0:16:35.160 --> 0:16:37.560 something's happening right now, what's going to happen at the 0:16:37.600 --> 0:16:39.560 next time step, and you can decide is it going 0:16:39.600 --> 0:16:41.920 to be a nanosecond in the future or ten minutes 0:16:41.960 --> 0:16:44.680 in the future. Depends on how much computing time you have. 0:16:45.000 --> 0:16:47.360 But it's very natural to step things forward in time 0:16:47.560 --> 0:16:50.960 in simulations, right, You do simulations with time steps. But 0:16:51.080 --> 0:16:53.440 simulations are not perfect, right, and that that's one of 0:16:53.440 --> 0:16:55.120 the main reasons is that they do have sort of 0:16:55.120 --> 0:16:58.520 a resolution. It doesn't do it continuously like the universe 0:16:58.560 --> 0:17:01.000 sort of seems to be. Yeah, exactly, they're not continuous, 0:17:01.000 --> 0:17:03.280 they're discreet. And you're right that you want really small 0:17:03.320 --> 0:17:06.840 time steps so that you're extrapolating in a reasonable way. 0:17:07.119 --> 0:17:09.600 But it might be that the universe actually does have 0:17:09.640 --> 0:17:11.280 the same sort of time steps, and if you did 0:17:11.280 --> 0:17:13.879 your simulation with a time step equal to that of 0:17:13.920 --> 0:17:17.439 the universe, then it would be perfect. But wow, that 0:17:17.440 --> 0:17:19.680 would be weird, right, Like the universe would be operating 0:17:19.880 --> 0:17:22.960 at the minimum possible time step because but the computer 0:17:23.119 --> 0:17:26.520 is in the universe, so that would blows my mind 0:17:26.520 --> 0:17:28.400 a little bit. But all right, So that's the first 0:17:28.480 --> 0:17:31.879 kind of time pixelization. What's the second. The second is 0:17:31.920 --> 0:17:35.560 that time isn't actually pixelized in the sense that you 0:17:35.640 --> 0:17:39.240 could have any value of time. It's not like values 0:17:39.280 --> 0:17:42.400 in between one point seven and one point eight are disallowed. 0:17:42.520 --> 0:17:44.800 If you try to measure like when did something happen? 0:17:45.160 --> 0:17:47.520 You could get any number between one point seven and 0:17:47.600 --> 0:17:50.840 one point eight. All those values are real and possible. 0:17:51.600 --> 0:17:54.800 In this idea, though, there's a minimum resolution, like you 0:17:54.840 --> 0:17:57.679 can't measure differences in time that are smaller than a 0:17:57.680 --> 0:18:00.520 certain number, Like if you measure something twice, you can't 0:18:00.520 --> 0:18:04.040 get two measurements that are closer than a certain minimum distance, 0:18:04.480 --> 0:18:06.560 but you can get any value. So it's sort of 0:18:06.600 --> 0:18:09.560 like you have this minimum resolution, but it can slide 0:18:09.640 --> 0:18:13.120 up and down the time scale where and land wherever. Okay, 0:18:13.119 --> 0:18:14.479 I think I know what you're saying. You're saying that 0:18:14.520 --> 0:18:18.320 maybe like every possible time step exists or is possible, 0:18:18.440 --> 0:18:21.200 like you can have one point oh three seconds and 0:18:21.320 --> 0:18:26.080 up one point two four seven seconds, but maybe at 0:18:26.119 --> 0:18:29.560 some point, at some scale of smallness and time, it 0:18:29.680 --> 0:18:34.200 just kind of becomes random or fuzzy or sort of unknowable. Yeah, exactly, 0:18:34.520 --> 0:18:36.560 And we can think about that because we think about 0:18:36.640 --> 0:18:41.560 quantum particles in exactly that way. Like an electron is quantized, right, 0:18:41.600 --> 0:18:45.560 it's a single object quantized of the electron field. So 0:18:45.640 --> 0:18:49.040 it's got a certain like natural width to it, below 0:18:49.040 --> 0:18:51.919 which you can't really probe where its location is, but 0:18:52.240 --> 0:18:55.879 it could be anywhere. It can live in continuous space. 0:18:56.200 --> 0:18:59.760 If space is continuous, you can still have discrete objects 0:18:59.800 --> 0:19:01.680 in side of it. And in that same way, time 0:19:01.720 --> 0:19:04.959 might be like fundamentally continuous, but there might be a 0:19:05.040 --> 0:19:08.680 minimum basic resolution of time below which the time difference 0:19:08.680 --> 0:19:12.560 between two events has no meaning, no meaning, but it exists, 0:19:12.560 --> 0:19:15.320 but it's sort of random. And because it's random, you're 0:19:15.359 --> 0:19:17.360 saying it doesn't have any meaning. But is that really 0:19:17.400 --> 0:19:20.720 pixelated though? Like it's so it doesn't fit our idea 0:19:20.720 --> 0:19:23.440 of a pixel, right, It's more like there's no pixel, 0:19:23.440 --> 0:19:25.800 but it's sort of fuzzy at a certain scale. Yeah, exactly. 0:19:25.800 --> 0:19:28.200 It sets a scale which I think that the physicist 0:19:28.320 --> 0:19:31.919 is interesting because it means that you can't infinitely divide time. 0:19:32.440 --> 0:19:34.360 That was the other part of Hendrick's question, like can 0:19:34.440 --> 0:19:37.920 you have infinitely small slices in time? Does it make 0:19:37.960 --> 0:19:40.800 sense to think about things happening at one moment and 0:19:40.840 --> 0:19:44.679 then tend to the minus one thousand seconds later, Like 0:19:44.760 --> 0:19:48.240 does their universe really evolve things step by step at 0:19:48.280 --> 0:19:51.119 that granularity. And what this would tell you is not 0:19:51.520 --> 0:19:54.320 that things are locked into specific numbers, but that it 0:19:54.400 --> 0:19:56.879 makes no sense to think about steps in time that 0:19:57.000 --> 0:20:00.880 are that small. You can just make stuff u It's 0:20:01.000 --> 0:20:05.119 unknown and it's undetermined, right in the same way that like, 0:20:05.280 --> 0:20:08.840 not all the information about an electron is knowable, not 0:20:08.920 --> 0:20:11.119 just because we can't measure it, but because it's not 0:20:11.280 --> 0:20:15.120 specified as undetermined. In that same way, pieces of time 0:20:15.240 --> 0:20:18.359 smaller than like whatever is the minimum resolution and time 0:20:18.760 --> 0:20:21.360 are not known or knowable. All right, Well, those are 0:20:21.359 --> 0:20:23.760 the two ways in which time could be pixelated, and 0:20:23.840 --> 0:20:26.399 so let's get into why we think it might be 0:20:26.400 --> 0:20:29.359 pixelated and whether or not we'll ever know if it 0:20:29.440 --> 0:20:31.720 is or not. But first let's take a quick break. 0:20:44.280 --> 0:20:48.560 All right, we're asking the question is time pixelated? And 0:20:48.640 --> 0:20:51.480 so we had a whole episode about whether space was pixelated, 0:20:51.640 --> 0:20:54.000 and we had all those reasons there. But now we're 0:20:54.000 --> 0:20:57.159 asking if time is pixelated, And so the question is 0:20:57.200 --> 0:20:59.600 why do we think time might be pixelated? It seems 0:20:59.640 --> 0:21:03.880 pretty continuous and smooth to me. It does seem continuous 0:21:03.960 --> 0:21:06.520 and smooth, but you know, our intuition breaks down when 0:21:06.520 --> 0:21:08.560 we try to apply it to things that are much 0:21:08.640 --> 0:21:12.040 much faster or much much smaller, and they reveal that 0:21:12.040 --> 0:21:14.720 the rules of the universe are really pretty different. Of course, 0:21:14.760 --> 0:21:17.240 when you zoom out to things like our skill, those 0:21:17.320 --> 0:21:21.679 rules do sort of coalesce to recover our experience. So 0:21:21.720 --> 0:21:23.600 it's amazing that you can have like one set of 0:21:23.680 --> 0:21:26.080 rules for the very tiny particles and it can all 0:21:26.160 --> 0:21:29.160 sort of work together to conspire to give a very 0:21:29.200 --> 0:21:31.920