1 00:00:07,800 --> 00:00:10,480 Speaker 1: Hey or hey, I think it's time we confronted a 2 00:00:10,600 --> 00:00:13,159 Speaker 1: really tricky topic. Do you think we have time for that? 3 00:00:13,520 --> 00:00:16,160 Speaker 1: You know, there's no time like the present. It could 4 00:00:16,200 --> 00:00:18,120 Speaker 1: be a good time. It might be a fun way 5 00:00:18,120 --> 00:00:20,599 Speaker 1: to pass some time. All right, I'll make time for it. 6 00:00:20,600 --> 00:00:28,320 Speaker 1: It's about time. That's so corny. How many time puns 7 00:00:28,360 --> 00:00:31,320 Speaker 1: can one fit into a single podcast? That's right? How 8 00:00:31,360 --> 00:00:35,400 Speaker 1: much time do you have? Um, I've got time. I 9 00:00:35,400 --> 00:00:38,559 Speaker 1: think it's a timely set of puns. Well, you use 10 00:00:38,680 --> 00:00:44,360 Speaker 1: that pun time after time, commending else. Now is the 11 00:00:44,440 --> 00:00:47,360 Speaker 1: time to start the podcast. Now is the time to 12 00:00:47,440 --> 00:01:07,640 Speaker 1: tackle this tricky topic. I am and I'm Daniel. It's 13 00:01:07,720 --> 00:01:11,000 Speaker 1: time for our podcast, Daniel and Jorge Explain the Universe, 14 00:01:11,160 --> 00:01:13,600 Speaker 1: a production of I Heart Radio in which we take 15 00:01:13,640 --> 00:01:17,000 Speaker 1: everything about the universe, the now, the future, the past, 16 00:01:17,200 --> 00:01:19,880 Speaker 1: the deep, deep, deep past and try to explain it 17 00:01:19,880 --> 00:01:22,600 Speaker 1: to you. That's worry. We take the time to take 18 00:01:22,640 --> 00:01:25,039 Speaker 1: a little bit of your time and maybe get you 19 00:01:25,080 --> 00:01:28,120 Speaker 1: to understand a little bit more about this amazing and 20 00:01:28,520 --> 00:01:31,680 Speaker 1: spacious place that we live in called the universe. That's right. 21 00:01:31,840 --> 00:01:34,560 Speaker 1: And sometimes we have to grapple with topics that are 22 00:01:34,640 --> 00:01:36,520 Speaker 1: sort of obvious. You know sort of things that are 23 00:01:36,600 --> 00:01:39,399 Speaker 1: right in front of you and understand like does physics 24 00:01:39,400 --> 00:01:41,360 Speaker 1: know how to make sense of it? Does physics have 25 00:01:41,400 --> 00:01:44,040 Speaker 1: a good definition of it? Do we understand why it's 26 00:01:44,080 --> 00:01:46,280 Speaker 1: this way and not that way? That's right? And so 27 00:01:46,319 --> 00:01:49,919 Speaker 1: today we're tackling a topic that is probably in everybody's 28 00:01:49,960 --> 00:01:53,000 Speaker 1: mind all the time. That's right. This is something you 29 00:01:53,040 --> 00:01:55,640 Speaker 1: think about every day from when your alarm clock goes 30 00:01:55,680 --> 00:01:57,720 Speaker 1: off to when it's time to go to bed. To 31 00:01:57,720 --> 00:02:05,760 Speaker 1: stay on the podcast, we will be talking about out time. 32 00:02:06,240 --> 00:02:09,280 Speaker 1: What is time anyway? Yeah? And why does it only 33 00:02:09,520 --> 00:02:12,640 Speaker 1: go forwards? Why do you remember the past and not 34 00:02:12,840 --> 00:02:15,440 Speaker 1: the future? Can you remember the future? That would be 35 00:02:15,480 --> 00:02:18,680 Speaker 1: pretty cool. Well, that's the whole question. Right on one hand, 36 00:02:19,080 --> 00:02:21,720 Speaker 1: very intuitive understanding of time. We all know what time 37 00:02:21,840 --> 00:02:25,480 Speaker 1: is right, yesterday was yesterday, tomorrow's tomorrow, right now is now, 38 00:02:26,040 --> 00:02:27,600 Speaker 1: But when you get down to it, we don't really 39 00:02:27,680 --> 00:02:30,799 Speaker 1: understand why we have it right. Why is it like that? 40 00:02:30,880 --> 00:02:33,800 Speaker 1: Why does it only go forwards? Why is the future 41 00:02:33,919 --> 00:02:36,040 Speaker 1: different from the past. Yeah, it's weird to think that 42 00:02:36,080 --> 00:02:37,880 Speaker 1: we are in the pressing right now and there's a 43 00:02:37,960 --> 00:02:41,119 Speaker 1: past going backwards in time, and there's a future going 44 00:02:41,120 --> 00:02:43,760 Speaker 1: forwards in time? But what's really the difference between those 45 00:02:43,800 --> 00:02:48,480 Speaker 1: two things? Yeah? Why can't I see or feel or 46 00:02:48,720 --> 00:02:51,480 Speaker 1: have any kind of memory about the future? Yeah? Exactly 47 00:02:51,480 --> 00:02:54,079 Speaker 1: what makes it different? Why is the past fixed? Right, 48 00:02:54,280 --> 00:02:58,160 Speaker 1: unchangeable unless you believe in crazy science fiction time travel stories, 49 00:02:58,160 --> 00:03:01,880 Speaker 1: which I don't, and the future undetermined? Right? What's the difference? 50 00:03:02,080 --> 00:03:05,680 Speaker 1: Can physics reveal that? Is there some understanding of time? 51 00:03:06,400 --> 00:03:08,680 Speaker 1: From physics? It tells us why one is different from 52 00:03:08,720 --> 00:03:11,239 Speaker 1: the other? Yeah? Why is there an arrow of time 53 00:03:11,320 --> 00:03:14,760 Speaker 1: like a one way sign in the universe, in the 54 00:03:14,840 --> 00:03:17,799 Speaker 1: highway of time of the universe? Yeah, this is one 55 00:03:17,800 --> 00:03:20,720 Speaker 1: of those wonderful questions because on the surface of it 56 00:03:20,720 --> 00:03:23,280 Speaker 1: it seems kind of dumb, Like somebody asks you what 57 00:03:23,480 --> 00:03:25,120 Speaker 1: is time? You're gonna tell him, Oh, it's three o'clock. 58 00:03:25,480 --> 00:03:27,240 Speaker 1: And if they dig deeper and ask you though, like 59 00:03:27,280 --> 00:03:30,000 Speaker 1: what does time even mean? Man? Sometimes I say it's 60 00:03:30,040 --> 00:03:34,400 Speaker 1: two o'clock. Depending on the circumstances, I always give the 61 00:03:34,400 --> 00:03:37,760 Speaker 1: same answer no matter what. That way, people stop asking. 62 00:03:38,560 --> 00:03:40,560 Speaker 1: My kids are aways what time is it? And they 63 00:03:40,560 --> 00:03:42,720 Speaker 1: have like a watch on their hand. There's like two 64 00:03:42,760 --> 00:03:44,840 Speaker 1: watches on the wall, Like why are you asking me? 65 00:03:44,880 --> 00:03:46,800 Speaker 1: So I would just say it's three o'clock no matter what, 66 00:03:47,160 --> 00:03:50,800 Speaker 1: so that they stop. It sounds like it sounds like 67 00:03:50,840 --> 00:03:53,400 Speaker 1: the same parenting strategy my my wife has when we 68 00:03:53,440 --> 00:03:55,640 Speaker 1: going road trips to always ask how long are we 69 00:03:55,760 --> 00:03:57,720 Speaker 1: do we get there? Is it? Are we there yet? 70 00:03:57,760 --> 00:04:01,240 Speaker 1: And she always answers, nope, scant twenty more hours, no 71 00:04:01,280 --> 00:04:03,680 Speaker 1: matter what. You're like pulling into the place, and she's like, 72 00:04:03,720 --> 00:04:07,480 Speaker 1: twenty more hours, yeah, no matter what, she always says 73 00:04:07,600 --> 00:04:10,280 Speaker 1: twenty It's a great strategy. You know, me and your wife, 74 00:04:10,320 --> 00:04:12,520 Speaker 1: we would really get along. It seems like we see 75 00:04:12,520 --> 00:04:15,520 Speaker 1: eye to eye about how to handle these approaches. How Tom, 76 00:04:17,080 --> 00:04:23,040 Speaker 1: you would have some very um sarcastic kids probably exactly. Um. Anyway, 77 00:04:23,080 --> 00:04:25,279 Speaker 1: I love these questions you know that are like, on 78 00:04:25,320 --> 00:04:28,760 Speaker 1: the surface so simple, when you dig deep, they reveal 79 00:04:28,880 --> 00:04:32,560 Speaker 1: like enormous gaps in our knowledge about the universe. Those 80 00:04:32,640 --> 00:04:35,760 Speaker 1: questions are the best because those are the opportunities to 81 00:04:35,839 --> 00:04:38,720 Speaker 1: reveal that the universe is different from the way we understood. 82 00:04:38,920 --> 00:04:41,240 Speaker 1: Like the way we think about the universe reflects just 83 00:04:41,560 --> 00:04:44,080 Speaker 1: our experience, the way we've lived and grown up, and 84 00:04:44,120 --> 00:04:47,520 Speaker 1: not something fundamental, something universal, right, And that's the whole 85 00:04:47,560 --> 00:04:50,520 Speaker 1: goal of physics. Yeah, it's one of those questions, like 86 00:04:51,000 --> 00:04:54,080 Speaker 1: it makes you kind of look almost inwards or look 87 00:04:54,120 --> 00:04:57,360 Speaker 1: in your like you one day you just wake up 88 00:04:57,360 --> 00:05:00,240 Speaker 1: and you don't even know where you're standing, or how 89 00:05:00,520 --> 00:05:02,560 Speaker 1: how the house that you live in was built. Who 90 00:05:02,880 --> 00:05:05,400 Speaker 1: don't lose grasp of reality there? Or or hey, we're 91 00:05:05,400 --> 00:05:08,520 Speaker 1: trying to dig deeper, trying to make you go crazy. 92 00:05:09,080 --> 00:05:11,120 Speaker 1: Doesn't it make it kind of question at like the 93 00:05:11,240 --> 00:05:13,960 Speaker 1: very nature of the universe. It does. It's sort of 94 00:05:14,000 --> 00:05:16,640 Speaker 1: like if you say a word like a hundred times, 95 00:05:16,680 --> 00:05:19,880 Speaker 1: like say the word marriage a hundred times, it starts 96 00:05:19,920 --> 00:05:21,840 Speaker 1: to turn into a really weird word. Right, you take 97 00:05:21,880 --> 00:05:23,840 Speaker 1: it apart, you look at you like, that's really strange. 98 00:05:24,279 --> 00:05:27,040 Speaker 1: It's the same thing with the concept of time, Like 99 00:05:27,360 --> 00:05:30,040 Speaker 1: you know, pick up your hand and rub your fingers together, right, 100 00:05:30,480 --> 00:05:34,080 Speaker 1: you're feeling that right now? Right? But what does now mean? 101 00:05:34,480 --> 00:05:38,599 Speaker 1: Right now? Sort of like it's always it's infinitely short, 102 00:05:38,640 --> 00:05:41,000 Speaker 1: and it's slipping constantly into the past. You can never 103 00:05:41,080 --> 00:05:43,280 Speaker 1: grasp onto it, you can never hold it, right, it's 104 00:05:43,520 --> 00:05:46,679 Speaker 1: always you're always losing it. It's a really strange concept 105 00:05:46,720 --> 00:05:50,760 Speaker 1: of concept of now. Yeah. Yeah, although I don't know 106 00:05:50,800 --> 00:05:55,720 Speaker 1: if that's what makes marriage weird. But there's lots of 107 00:05:55,760 --> 00:05:58,320 Speaker 1: things that make marriage weird. Um, saying it a hundred 108 00:05:58,360 --> 00:06:01,239 Speaker 1: times is not it. But I remember reading a book 109 00:06:01,360 --> 00:06:03,800 Speaker 1: about consciousness back when I was really interested in the 110 00:06:03,800 --> 00:06:06,240 Speaker 1: science of consciousness, which we can talk about another podcast. 111 00:06:06,480 --> 00:06:09,080 Speaker 1: But the basic idea in that book, as by Daniel 112 00:06:09,120 --> 00:06:12,039 Speaker 1: Dennit it's called Consciousness Explained, is that there is no 113 00:06:12,040 --> 00:06:15,719 Speaker 1: now that you're the consciousness is basically an illusion that 114 00:06:15,839 --> 00:06:19,920 Speaker 1: all you're ever doing is remembering the immediate past. And 115 00:06:20,040 --> 00:06:21,440 Speaker 1: I don't know if I believe that, but it really 116 00:06:21,440 --> 00:06:23,839 Speaker 1: made me think about what now is and how you 117 00:06:23,880 --> 00:06:26,240 Speaker 1: can never really grasp it. It's always just like sliding 118 00:06:26,279 --> 00:06:28,800 Speaker 1: away from you and you know, whether it really exists, 119 00:06:28,839 --> 00:06:31,600 Speaker 1: whether there is a now, right, whether there's a special 120 00:06:31,720 --> 00:06:35,000 Speaker 1: instant that that differentiates between the past and the future 121 00:06:35,560 --> 00:06:39,120 Speaker 1: right right, because sort of technically in physics of time 122 00:06:39,400 --> 00:06:42,600 Speaker 1: could go both ways right like you could in time 123 00:06:42,680 --> 00:06:44,279 Speaker 1: is kind of just like an arrow you can flip 124 00:06:44,279 --> 00:06:47,080 Speaker 1: back and forth in the equations that you guys use, right. Yeah, 125 00:06:47,200 --> 00:06:49,800 Speaker 1: time is not really very central to physics. Yeah, I mean, 126 00:06:49,920 --> 00:06:51,520 Speaker 1: on one hand, it is. On one hand, it isn't. 127 00:06:51,560 --> 00:06:53,760 Speaker 1: Tom you could write a lot of physics down without 128 00:06:53,800 --> 00:06:56,600 Speaker 1: ever thinking about time. On the other hand, time is 129 00:06:57,160 --> 00:06:59,400 Speaker 1: essential property physics because we're trying to use physics to 130 00:06:59,520 --> 00:07:03,000 Speaker 1: predict the future. So um, this time is both like 131 00:07:03,279 --> 00:07:05,920 Speaker 1: not part of physics and deeply entwined in it at 132 00:07:05,920 --> 00:07:09,720 Speaker 1: the same time. So it's, uh, it's an important topic. Yeah, no, 133 00:07:09,800 --> 00:07:12,920 Speaker 1: And it's a topic that everybody experiences right at every 134 00:07:12,960 --> 00:07:15,960 Speaker 1: second of the day, every day of the year, every 135 00:07:16,040 --> 00:07:19,360 Speaker 1: year their lives. They're experiencing time, and they're moving forwards 136 00:07:19,440 --> 00:07:22,440 Speaker 1: in it, and they feel it, right. Yeah, they think 137 00:07:22,480 --> 00:07:24,840 Speaker 1: about it, they think about the future, they remember the past, 138 00:07:24,880 --> 00:07:27,920 Speaker 1: and so it kind of makes you wonder how many 139 00:07:27,960 --> 00:07:35,120 Speaker 1: people actually think about or know what time actually is. Yeah, exactly. 140 00:07:35,720 --> 00:07:39,800 Speaker 1: So I was wondering do people know why time goes forward? Like, 141 00:07:39,960 --> 00:07:42,160 Speaker 1: I mean, physicists don't really, but it's always fun to 142 00:07:42,200 --> 00:07:46,200 Speaker 1: ask general public questions that scientists don't know the answer to, 143 00:07:46,320 --> 00:07:48,640 Speaker 1: just to see what they come up with. So I 144 00:07:48,680 --> 00:07:50,600 Speaker 1: walked around the US of Irvine campus and I asked 145 00:07:50,640 --> 00:07:53,760 Speaker 1: people why does time only go forwards? Here's what people 146 00:07:53,760 --> 00:07:58,480 Speaker 1: had to say. Do you know why time only goes forwards? Um? 147 00:07:58,520 --> 00:08:02,120 Speaker 1: Not really, honestly, I have like some sort of like 148 00:08:02,640 --> 00:08:05,960 Speaker 1: intuition why it only goes forward? But I don't think 149 00:08:05,960 --> 00:08:10,920 Speaker 1: we can't explain that. Yeah, okay, cool, I have no idea. No, 150 00:08:10,960 --> 00:08:12,880 Speaker 1: I don't any guess. If I had to go, I 151 00:08:12,960 --> 00:08:16,960 Speaker 1: just said gravity or something. Okay, No, I don't any idea, 152 00:08:17,040 --> 00:08:22,360 Speaker 1: best guess. Sorry. I think time is lack of force 153 00:08:22,520 --> 00:08:28,920 Speaker 1: dimensional right, So actually I don't know, creaky right, Okay, 154 00:08:29,600 --> 00:08:35,000 Speaker 1: I'm not sure. Okay, Well, when I think of time, 155 00:08:35,040 --> 00:08:37,400 Speaker 1: I think of it kind of almost as a linear progression, 156 00:08:38,240 --> 00:08:42,000 Speaker 1: meaning that it's a constant in the universe, and it's 157 00:08:42,040 --> 00:08:44,040 Speaker 1: always kind of moving forward, and that's something that we 158 00:08:44,120 --> 00:08:47,120 Speaker 1: accept as being a fact of the universe, at least 159 00:08:47,120 --> 00:08:49,679 Speaker 1: as we understand it now. So in that regards, I 160 00:08:49,760 --> 00:08:52,200 Speaker 1: think that's why we can only see it as moving forwards, 161 00:08:52,200 --> 00:08:54,319 Speaker 1: because it doesn't kind of make sense to us or 162 00:08:54,360 --> 00:08:57,120 Speaker 1: it's not even physically possible currently for us to move 163 00:08:57,160 --> 00:09:00,240 Speaker 1: backwards in time, so we don't consider it in that way. 164 00:09:00,280 --> 00:09:02,880 Speaker 1: I think it might be a matter of observation. So 165 00:09:03,000 --> 00:09:05,880 Speaker 1: relative to us, time moves forward, and the way that 166 00:09:05,920 --> 00:09:09,240 Speaker 1: you experienced the world biologically is designed to be in 167 00:09:09,240 --> 00:09:12,400 Speaker 1: a manner that is sort of one dimentional and a 168 00:09:12,440 --> 00:09:16,079 Speaker 1: forward mind all the time. But in reality it might 169 00:09:16,160 --> 00:09:20,760 Speaker 1: be that the fourth dimension of time in space time 170 00:09:20,840 --> 00:09:23,040 Speaker 1: might just be a way of describing the universe that 171 00:09:23,080 --> 00:09:27,520 Speaker 1: the math predicts a from physics and my option perhaps 172 00:09:27,520 --> 00:09:30,880 Speaker 1: other related science fills. Okay, cool, Yeah, so I got 173 00:09:30,960 --> 00:09:33,360 Speaker 1: a pretty good mix of answers there, right from the 174 00:09:33,559 --> 00:09:36,720 Speaker 1: standard physics, like gravity, which is you know, that's a 175 00:09:36,720 --> 00:09:39,640 Speaker 1: good answer. You never know, it might be, right, gravity. 176 00:09:40,160 --> 00:09:44,079 Speaker 1: Somebody actually said gravity. I don't know gravity, It could 177 00:09:44,080 --> 00:09:46,120 Speaker 1: be it could be. Yeah, well, gravity is like the 178 00:09:46,120 --> 00:09:48,120 Speaker 1: answer to half the questions in physics, the way like 179 00:09:48,520 --> 00:09:50,679 Speaker 1: pie is the answer to half the questions in math. Right, 180 00:09:50,679 --> 00:09:52,240 Speaker 1: so if you have no idea, you could just say 181 00:09:52,240 --> 00:09:55,240 Speaker 1: gravity and have the time. You'll be right. Not the 182 00:09:55,240 --> 00:09:59,880 Speaker 1: movie the fourth right, yeah, the fabric of space time itself. 183 00:10:00,080 --> 00:10:02,440 Speaker 1: That's right, it's gravity. Yeah. And then you know, some 184 00:10:02,480 --> 00:10:07,400 Speaker 1: other folks had some more elaborate discussions, But people had opinions. 185 00:10:07,600 --> 00:10:10,120 Speaker 1: People did have opinions. Yeah, some of them were sort 186 00:10:10,160 --> 00:10:12,559 Speaker 1: of longer word salad. Right, you know, some of them 187 00:10:12,640 --> 00:10:14,960 Speaker 1: hit on some of the scientific concepts time being a 188 00:10:15,000 --> 00:10:19,160 Speaker 1: fourth dimension, etcetera. Um, but um, yeah, a lot of 189 00:10:19,160 --> 00:10:20,719 Speaker 1: people want to ask them this question. You could just 190 00:10:20,760 --> 00:10:23,560 Speaker 1: see in their faces that they had not ever considered this. 191 00:10:23,640 --> 00:10:26,480 Speaker 1: They're not even question they had imagined, but as soon 192 00:10:26,520 --> 00:10:28,720 Speaker 1: as they thought about it, they realized they didn't know. 193 00:10:28,840 --> 00:10:31,960 Speaker 1: And that's my favorite part of this this topic is 194 00:10:31,960 --> 00:10:34,680 Speaker 1: that nobody, nobody has really thought about it in terms 195 00:10:34,720 --> 00:10:37,320 Speaker 1: of general public, but as soon as they do, they're 196 00:10:37,480 --> 00:10:40,760 Speaker 1: very curious. Right, this is the best questions. It's amazing 197 00:10:40,760 --> 00:10:43,520 Speaker 1: how little you actually kind of need to know about 198 00:10:43,520 --> 00:10:47,680 Speaker 1: the universe to live a full and happy life, you 199 00:10:47,720 --> 00:10:51,360 Speaker 1: know what I mean, that's the protective happy life. There's 200 00:10:51,400 --> 00:10:53,720 Speaker 1: so much you don't need to know. Ignorance is bliss, 201 00:10:53,800 --> 00:10:55,520 Speaker 1: you know, that does have a meeting. People have been 202 00:10:55,559 --> 00:10:58,600 Speaker 1: living in this universe for hundreds of thousands of years, 203 00:10:58,600 --> 00:11:01,480 Speaker 1: depending on how you count the beginning of humanity, and 204 00:11:01,559 --> 00:11:03,720 Speaker 1: there's been a lot of happiness and joy without really 205 00:11:03,760 --> 00:11:07,520 Speaker 1: any understanding. I mean, I would say people five years 206 00:11:07,520 --> 00:11:11,480 Speaker 1: ago basically knew nothing about the way the universe actually works. 207 00:11:11,520 --> 00:11:14,960 Speaker 1: But you know, people had birthday parties and eight cakes 208 00:11:15,040 --> 00:11:17,840 Speaker 1: and had moments of joy. So yeah, I mean like 209 00:11:17,880 --> 00:11:20,280 Speaker 1: a hundred only a hundred years ago, right in the 210 00:11:20,440 --> 00:11:25,080 Speaker 1: nine hundreds, early nineteen hundreds, people didn't know the concept 211 00:11:25,160 --> 00:11:28,320 Speaker 1: of Adams or quantum physics, right, Yeah, that was about 212 00:11:28,360 --> 00:11:30,160 Speaker 1: a hundred years old. We didn't know how long the 213 00:11:30,240 --> 00:11:33,920 Speaker 1: universe had been around, right, so pretty basic stuff about 214 00:11:33,920 --> 00:11:36,280 Speaker 1: the way the universe works is pretty modern. Right, So 215 00:11:36,440 --> 00:11:39,560 Speaker 1: we didn't know there were other galaxies, right, No, they didn't. Um, 216 00:11:39,600 --> 00:11:41,240 Speaker 1: So what's your point here? Your point is you don't 217 00:11:41,280 --> 00:11:42,880 Speaker 1: need physics to be happy? Is that what you're trying 218 00:11:42,880 --> 00:11:46,760 Speaker 1: to say is irrelevant happiness? You think of how much 219 00:11:46,760 --> 00:11:50,800 Speaker 1: of a richer life you can lead if you know physics. Okay, 220 00:11:50,880 --> 00:11:53,520 Speaker 1: I like the way you spun that back, right, using 221 00:11:53,559 --> 00:11:56,280 Speaker 1: all this technology to talk to me. That's based on physics, 222 00:11:56,640 --> 00:11:58,960 Speaker 1: not not like not like money rich, but you know, 223 00:11:59,120 --> 00:12:03,400 Speaker 1: like spiritually right right? Um? Isn't your career based on 224 00:12:03,520 --> 00:12:07,960 Speaker 1: technology that was developed with the help of physicists? Where 225 00:12:07,960 --> 00:12:14,480 Speaker 1: would you be? Isn't your science dependent on technology? Yes? 226 00:12:14,559 --> 00:12:16,960 Speaker 1: I am a tiny little mite standing on the shoulders 227 00:12:16,960 --> 00:12:19,720 Speaker 1: of giants, absolutely, But so are we all? So are 228 00:12:19,760 --> 00:12:26,199 Speaker 1: we all? Yeah? Well maybe it's time we got back 229 00:12:26,240 --> 00:12:28,400 Speaker 1: on topic here, and um, so let's break it down 230 00:12:28,400 --> 00:12:31,600 Speaker 1: for people, Daniel, what how do physicists see time? Like 231 00:12:31,960 --> 00:12:34,160 Speaker 1: if if you're at a conference and you guys are 232 00:12:34,160 --> 00:12:36,400 Speaker 1: talking and somebody said, hey, guys, what is time? What 233 00:12:36,480 --> 00:12:39,280 Speaker 1: do you think people would generally say, I think there'd 234 00:12:39,280 --> 00:12:42,080 Speaker 1: be a lot of disagreements because we don't really have 235 00:12:42,320 --> 00:12:45,160 Speaker 1: a great description of time, you know, one that really 236 00:12:45,200 --> 00:12:47,760 Speaker 1: makes sense. And you know, the way physics approaches the 237 00:12:47,880 --> 00:12:50,440 Speaker 1: problem is first you try to build like a model 238 00:12:50,480 --> 00:12:52,200 Speaker 1: of the problem. You're trying to describe it in a 239 00:12:52,240 --> 00:12:55,280 Speaker 1: way that we can grapple using the language that we're 240 00:12:55,280 --> 00:12:58,240 Speaker 1: familiar with, which is mathematics. You try to find an 241 00:12:58,240 --> 00:13:03,359 Speaker 1: equation that tells you what what's what's happening? Yeah, exactly, 242 00:13:03,520 --> 00:13:05,839 Speaker 1: you know, something's happening in the real world. Maybe it's 243 00:13:05,880 --> 00:13:08,240 Speaker 1: like a ball is being thrown the air, and we 244 00:13:08,360 --> 00:13:10,360 Speaker 1: try to understand it. So we write down a bunch 245 00:13:10,360 --> 00:13:13,199 Speaker 1: of equations to describe it um and that lets us 246 00:13:13,440 --> 00:13:15,720 Speaker 1: build that model in our heads and manipulate it and 247 00:13:15,720 --> 00:13:18,920 Speaker 1: then use information from the model to describe what's happening 248 00:13:18,920 --> 00:13:21,920 Speaker 1: in the world. Cool. How do we do that with time? Right? 249 00:13:21,960 --> 00:13:24,200 Speaker 1: How do we ask this question about like why can 250 00:13:24,280 --> 00:13:27,280 Speaker 1: I remember the past and not the future? Why does 251 00:13:27,440 --> 00:13:31,120 Speaker 1: ice melt but not unmelt? Right? These kinds of questions 252 00:13:31,160 --> 00:13:35,560 Speaker 1: about time, it's pretty hard to to wrap your mind around. 253 00:13:36,320 --> 00:13:39,880 Speaker 1: One approach is to think about the universe in terms 254 00:13:39,880 --> 00:13:43,520 Speaker 1: of a bunch of snapshots. Like you think about a movie. Right, 255 00:13:43,559 --> 00:13:46,839 Speaker 1: what is a movie? It's not really a continuous experience 256 00:13:46,840 --> 00:13:48,840 Speaker 1: in time. If you're looking at the screen, you're not 257 00:13:48,920 --> 00:13:52,480 Speaker 1: really seeing smooth motion. You're seeing a bunch of snapshots. 258 00:13:52,679 --> 00:13:54,840 Speaker 1: You're seeing like a little cells in a film, or 259 00:13:54,920 --> 00:13:58,319 Speaker 1: like a bunch of screenshots. Yeah, it's a bunch of screenshots, 260 00:13:58,520 --> 00:14:00,760 Speaker 1: and they're just packed so tightly together that you don't 261 00:14:00,840 --> 00:14:04,120 Speaker 1: notice that they're not actually smoothly varying. Right. Your brain 262 00:14:04,160 --> 00:14:06,880 Speaker 1: does the interpolation for you. It tells you a story. 263 00:14:06,960 --> 00:14:10,000 Speaker 1: So sometimes we think about the universe that way. We 264 00:14:10,040 --> 00:14:13,440 Speaker 1: think about like all the universe at this moment, and 265 00:14:13,480 --> 00:14:15,800 Speaker 1: then all the universe at the next moment, and all 266 00:14:15,800 --> 00:14:18,920 Speaker 1: the universe at the next moment, like snapshots of the universe. 267 00:14:19,240 --> 00:14:22,360 Speaker 1: By snapshots, I mean like what is every particle doing 268 00:14:23,120 --> 00:14:27,040 Speaker 1: and where is it going? Yeah, exactly and time. Then 269 00:14:27,360 --> 00:14:29,640 Speaker 1: is a way to sort of order those snapshots is 270 00:14:29,680 --> 00:14:32,760 Speaker 1: to say this one first, that one next, that one next, 271 00:14:33,360 --> 00:14:35,360 Speaker 1: um and to sort of put them together. This one 272 00:14:35,440 --> 00:14:37,520 Speaker 1: can go in front of the other one. Yes, you 273 00:14:37,560 --> 00:14:41,680 Speaker 1: know what I mean. It limits um the ordering. Yeah, 274 00:14:41,760 --> 00:14:46,040 Speaker 1: And in that sense, physics. The job of physics is 275 00:14:46,080 --> 00:14:48,800 Speaker 1: to take all the snapshots in the past and predict 276 00:14:48,840 --> 00:14:51,400 Speaker 1: the ones in the future and to say, Okay, according 277 00:14:51,440 --> 00:14:53,800 Speaker 1: to the laws of physics, the next snapshot will look 278 00:14:53,840 --> 00:14:56,520 Speaker 1: like this, or if you want to talk quantum mechanically, 279 00:14:56,880 --> 00:15:00,920 Speaker 1: there's a probability distribution of the next snapshots. These are likely, 280 00:15:00,960 --> 00:15:04,680 Speaker 1: these are unlikely, these are impossible. Right, So physics um 281 00:15:04,960 --> 00:15:06,920 Speaker 1: takes sort of that view of time, and there's a 282 00:15:06,920 --> 00:15:09,080 Speaker 1: bunch of caveats there. Like, you can't have a snapshot 283 00:15:09,120 --> 00:15:12,080 Speaker 1: of the whole universe, right because time is not universal. 284 00:15:12,400 --> 00:15:14,600 Speaker 1: It means different things for different people. You can't know 285 00:15:14,640 --> 00:15:17,280 Speaker 1: everything about the universe. But you know, you take a 286 00:15:17,280 --> 00:15:20,000 Speaker 1: small enough model or a single particle or something, you 287 00:15:20,000 --> 00:15:23,040 Speaker 1: can also have quantum and you also have quantum states, 288 00:15:23,160 --> 00:15:25,840 Speaker 1: right Like it' isn't that prevent you from getting an 289 00:15:25,880 --> 00:15:29,080 Speaker 1: exact snapshot of the universe? Yeah, exactly. So you can't 290 00:15:29,080 --> 00:15:30,880 Speaker 1: really get an exact snapshot, but you could do a 291 00:15:30,960 --> 00:15:33,680 Speaker 1: quantum mechanical version. You could say, well, what's the quantum 292 00:15:33,720 --> 00:15:35,840 Speaker 1: state of all the particles or you know, what's the 293 00:15:36,360 --> 00:15:38,640 Speaker 1: wave function. What's the state of the wave function right 294 00:15:38,640 --> 00:15:41,680 Speaker 1: now that you can talk about, and that determines probabilities. 295 00:15:42,040 --> 00:15:43,960 Speaker 1: I see, So you describe me kind of how physicists 296 00:15:44,040 --> 00:15:46,720 Speaker 1: see the universe. They don't see it as um. They 297 00:15:46,760 --> 00:15:50,000 Speaker 1: see it as as this kind of sequence of snapshots 298 00:15:50,120 --> 00:15:53,200 Speaker 1: of how things are arranged. Yeah. For example, think about 299 00:15:53,360 --> 00:15:57,120 Speaker 1: the Shortinger equation. The Shortinger equation famous equation describes how 300 00:15:57,160 --> 00:16:01,280 Speaker 1: a particles a wave function um moves through time, right, 301 00:16:02,120 --> 00:16:04,160 Speaker 1: and it tells you how it moves. It says, if 302 00:16:04,200 --> 00:16:07,160 Speaker 1: you have this wave function now and you experience this, 303 00:16:07,240 --> 00:16:09,480 Speaker 1: then your way function will be that later. Right. So 304 00:16:09,560 --> 00:16:12,120 Speaker 1: that's that's what physics tries to do, or or go 305 00:16:12,200 --> 00:16:14,120 Speaker 1: back to them making the mechanical example of a ball 306 00:16:14,160 --> 00:16:16,040 Speaker 1: going through the air right tells you, well, you you 307 00:16:16,080 --> 00:16:18,560 Speaker 1: shot your ball in this direction. Where is your ball 308 00:16:18,600 --> 00:16:21,120 Speaker 1: going to be in the future. So that's the role 309 00:16:21,160 --> 00:16:24,360 Speaker 1: of time in physics, right to predict the future snapshots. Oh, 310 00:16:24,440 --> 00:16:27,200 Speaker 1: I see. So to you guys, time is like a 311 00:16:27,800 --> 00:16:31,400 Speaker 1: like an input that tells you what the universe is 312 00:16:31,440 --> 00:16:33,240 Speaker 1: likely to do. You you know what I mean? Like 313 00:16:33,280 --> 00:16:35,520 Speaker 1: you do you It's an input. It's not like an 314 00:16:35,520 --> 00:16:40,600 Speaker 1: output or something that you can vary or that it 315 00:16:40,680 --> 00:16:43,880 Speaker 1: is affected by all the other variables. Yeah, exactly. And 316 00:16:43,920 --> 00:16:46,200 Speaker 1: so for example, you want to predict the flight of 317 00:16:46,240 --> 00:16:48,160 Speaker 1: your ball, it's an input. You can dial that knob 318 00:16:48,160 --> 00:16:49,320 Speaker 1: and say I want to know where the ball is 319 00:16:49,320 --> 00:16:51,280 Speaker 1: going to be in one second or five seconds or 320 00:16:51,360 --> 00:16:54,520 Speaker 1: eight point two nine seconds or whatever. So it's sort 321 00:16:54,520 --> 00:16:57,040 Speaker 1: of that knob. The thing we don't the thing that 322 00:16:57,040 --> 00:17:00,360 Speaker 1: that doesn't explain at all is like why it only 323 00:17:00,360 --> 00:17:03,440 Speaker 1: go forwards and who's controlling how fast that knob is turning? 324 00:17:03,560 --> 00:17:05,880 Speaker 1: Or why do we have time at all? Why don't 325 00:17:05,880 --> 00:17:08,000 Speaker 1: we just have a static universe? It's just sort of 326 00:17:08,040 --> 00:17:12,160 Speaker 1: like there, you know, it's the first step. Of course, 327 00:17:12,160 --> 00:17:14,120 Speaker 1: they just try to describe it, and then you can 328 00:17:14,160 --> 00:17:16,600 Speaker 1: build from that and try to answer some of these questions. 329 00:17:16,800 --> 00:17:18,399 Speaker 1: But you mean, like, how come we don't have a 330 00:17:18,440 --> 00:17:21,360 Speaker 1: static universe, Like, um, why do we have time at all? 331 00:17:21,640 --> 00:17:26,439 Speaker 1: Boom right, I don't know, you don't know, nobody knows, Like, well, 332 00:17:26,480 --> 00:17:29,600 Speaker 1: I know, there's this idea that time is the fourth dimensions. 333 00:17:29,640 --> 00:17:32,640 Speaker 1: We have three dimensions up, down, left and right, backwards 334 00:17:32,640 --> 00:17:36,520 Speaker 1: and forwards, and maybe time is just another direction of 335 00:17:36,560 --> 00:17:39,040 Speaker 1: the universe. And so we and I think the days 336 00:17:39,040 --> 00:17:42,439 Speaker 1: that we do sort of exist in this a state 337 00:17:42,600 --> 00:17:47,040 Speaker 1: of being still in all four dimensions, but it just 338 00:17:47,080 --> 00:17:51,240 Speaker 1: so happens that we somehow feel one of the mensitions. 339 00:17:51,320 --> 00:17:52,760 Speaker 1: Do you know what I mean? Yeah? I love the 340 00:17:53,040 --> 00:17:56,399 Speaker 1: it just so happens part of that explanation, right, Okay, 341 00:17:56,440 --> 00:17:58,880 Speaker 1: here's the hardest part. I'll just YadA, YadA, YadA over 342 00:17:58,920 --> 00:18:03,119 Speaker 1: that bit. That's that's my that's my Nobel Prize, Nobel 343 00:18:03,200 --> 00:18:06,000 Speaker 1: Prize winning paper officer. It just so happens. I was 344 00:18:06,040 --> 00:18:08,600 Speaker 1: going ninety miles an hour. Um, you know, I can't 345 00:18:08,640 --> 00:18:11,520 Speaker 1: explain it now, You're right. Um, time is sometimes thought 346 00:18:11,520 --> 00:18:13,800 Speaker 1: of as the fourth dimension. And so let's dig into 347 00:18:13,840 --> 00:18:15,320 Speaker 1: that a little bit. What does that mean? Why do 348 00:18:15,400 --> 00:18:17,199 Speaker 1: we think of it that way? We think of it 349 00:18:17,240 --> 00:18:21,080 Speaker 1: that way because it's helpful mathematically. Like when Einstein was 350 00:18:21,080 --> 00:18:24,040 Speaker 1: developing his theory of special relativity and we talked all 351 00:18:24,080 --> 00:18:27,160 Speaker 1: about time dilation and stuff like that on a previous episode, 352 00:18:27,600 --> 00:18:30,920 Speaker 1: he discovered that the equations have a certain symmetry. They 353 00:18:30,960 --> 00:18:33,560 Speaker 1: look really nice like that you can write them down 354 00:18:33,640 --> 00:18:37,119 Speaker 1: really simply and compactly if you include time as the 355 00:18:37,160 --> 00:18:40,600 Speaker 1: fourth dimension of this larger concept he called space time. 356 00:18:40,880 --> 00:18:43,320 Speaker 1: So he took three dimensions of space. He tacked on 357 00:18:43,359 --> 00:18:46,240 Speaker 1: a fourth dimension, which is time, and he constructed this 358 00:18:46,280 --> 00:18:50,320 Speaker 1: thing called space time. And because your perception of time 359 00:18:50,359 --> 00:18:53,359 Speaker 1: depends on where you are in space and how fast 360 00:18:53,440 --> 00:18:56,800 Speaker 1: you are moving through space, the equations get much simpler 361 00:18:57,080 --> 00:19:00,199 Speaker 1: if you think about all four dimensions in that way, right, 362 00:19:00,200 --> 00:19:02,720 Speaker 1: if you think about time parallel to space in that way. 363 00:19:03,000 --> 00:19:06,119 Speaker 1: And that's a clue when you write down equations, and 364 00:19:06,160 --> 00:19:08,199 Speaker 1: they become simpler if you think about them a certain way. 365 00:19:08,240 --> 00:19:10,119 Speaker 1: That's a clue from the universe that it's maybe the 366 00:19:10,240 --> 00:19:13,359 Speaker 1: right way to think about things. Okay, so that's um, 367 00:19:13,400 --> 00:19:16,199 Speaker 1: that's time is a different dimension. Let's get more into it. 368 00:19:16,280 --> 00:19:18,840 Speaker 1: Let's go down that rabbit hole. But first let's take 369 00:19:18,880 --> 00:19:33,920 Speaker 1: a quick break. So I think it's fun to think 370 00:19:33,920 --> 00:19:36,920 Speaker 1: about time as the fourth dimension. But it's also kind 371 00:19:36,960 --> 00:19:39,760 Speaker 1: of a trick, right, It's not. It doesn't really fit. 372 00:19:40,359 --> 00:19:42,560 Speaker 1: So wait, So the idea that it's a fourth dimension 373 00:19:42,760 --> 00:19:48,399 Speaker 1: you're saying, came from mathematical convenience by Einstein, do you 374 00:19:48,400 --> 00:19:50,919 Speaker 1: know what I mean? Like, it's not. It was just 375 00:19:51,040 --> 00:19:54,560 Speaker 1: easier to treat it like a dimension. Yeah, And I 376 00:19:54,600 --> 00:19:57,560 Speaker 1: wouldn't you blow that off? Mathematical convenience is not a 377 00:19:57,600 --> 00:20:00,399 Speaker 1: small thing, you know. The whole goal of physics, remember, 378 00:20:00,480 --> 00:20:02,560 Speaker 1: is to like write down an equation of the universe 379 00:20:02,560 --> 00:20:05,720 Speaker 1: in one line. And so if you can write things 380 00:20:05,760 --> 00:20:08,600 Speaker 1: more simply, that's a clue that it's probably more correct, 381 00:20:08,640 --> 00:20:12,360 Speaker 1: it's more and it's like a deeper understanding. So yeah, 382 00:20:12,400 --> 00:20:14,640 Speaker 1: he discovered that if you write things down with time 383 00:20:14,720 --> 00:20:17,920 Speaker 1: is sort of the fourth column of your vector, then 384 00:20:18,040 --> 00:20:20,160 Speaker 1: a lot of the equations are simpler to write down. 385 00:20:20,160 --> 00:20:22,480 Speaker 1: There's it's there's a connection. There's a symmetry there. Right. 386 00:20:22,560 --> 00:20:25,359 Speaker 1: We talked about symmetry in another episode. You can treat 387 00:20:25,400 --> 00:20:28,359 Speaker 1: time the same way you treat space in many ways. 388 00:20:29,280 --> 00:20:31,520 Speaker 1: And that's that's tempting because you think, oh, well, that 389 00:20:31,560 --> 00:20:34,040 Speaker 1: answers the question time is just another dimension, right, But 390 00:20:34,080 --> 00:20:37,280 Speaker 1: it doesn't answer the question because it's not just another dimension. Right. 391 00:20:37,560 --> 00:20:40,800 Speaker 1: You know time is not space? Right? Time? What does 392 00:20:40,800 --> 00:20:44,479 Speaker 1: that mean? Time is not space? Well, for money, you 393 00:20:44,520 --> 00:20:46,760 Speaker 1: can move forwards and backwards in space, right, you can 394 00:20:46,800 --> 00:20:49,119 Speaker 1: go left, you can go right, you have some control 395 00:20:49,160 --> 00:20:52,120 Speaker 1: over it. You can't do that with time. But isn't 396 00:20:52,119 --> 00:20:55,840 Speaker 1: it just sort of a matter of perspective, Like I think, 397 00:20:56,160 --> 00:21:01,000 Speaker 1: like in the grand scheme of the history of the universe, Um, 398 00:21:01,040 --> 00:21:03,679 Speaker 1: you know, I existed for this amount of time, but 399 00:21:03,840 --> 00:21:06,280 Speaker 1: while I'm living it, I can only go forward. I 400 00:21:06,320 --> 00:21:09,640 Speaker 1: kind of get the experience of moving forward in time. Yeah, 401 00:21:09,640 --> 00:21:12,480 Speaker 1: that's true. Technically, I sort of existed all throughout my 402 00:21:12,520 --> 00:21:16,680 Speaker 1: life in space time, you existed all throughout your life, Yeah, 403 00:21:16,760 --> 00:21:19,800 Speaker 1: but you don't exist all throughout time. Right, There's no 404 00:21:19,920 --> 00:21:21,879 Speaker 1: limit to where you can visit. In space, you can 405 00:21:21,920 --> 00:21:24,240 Speaker 1: go from here to there to the other places. But 406 00:21:24,320 --> 00:21:27,600 Speaker 1: in time, you can only visit between your birth and 407 00:21:27,640 --> 00:21:31,160 Speaker 1: your death, and you can only go to each time once. Right, 408 00:21:31,280 --> 00:21:33,240 Speaker 1: that's not true for space. I imagine there are lots 409 00:21:33,240 --> 00:21:35,320 Speaker 1: of places you go to many many times, like your 410 00:21:35,320 --> 00:21:39,560 Speaker 1: refrigerator or your bed. Right, Um, you visit those places 411 00:21:39,600 --> 00:21:42,680 Speaker 1: many times. So space is quite different from time. Right, 412 00:21:43,160 --> 00:21:45,520 Speaker 1: there's a special loops in space, but I can't do 413 00:21:45,640 --> 00:21:50,000 Speaker 1: loops in time exactly. And time time has this special difference. 414 00:21:50,119 --> 00:21:53,680 Speaker 1: Right then now, right, there's no now in space. I mean, 415 00:21:53,760 --> 00:21:57,120 Speaker 1: I'm here, I'm there, you're over here, but there's no 416 00:21:57,280 --> 00:22:00,959 Speaker 1: there's no special location in a what time has this 417 00:22:01,359 --> 00:22:05,520 Speaker 1: special location? This thing we call now, which exists weirdly 418 00:22:05,880 --> 00:22:09,080 Speaker 1: and slides forward weirdly. So I was saying earlier, wh 419 00:22:09,240 --> 00:22:11,440 Speaker 1: why isn't the universe static? Why is time move forwards? 420 00:22:11,440 --> 00:22:13,880 Speaker 1: Why isn't it just stuck at to equal zero? Nothing happens? 421 00:22:14,040 --> 00:22:17,960 Speaker 1: What's pushing it forward? What's turning the engine of the universe? Right? 422 00:22:18,240 --> 00:22:19,959 Speaker 1: I guess what I mean is, you know, if time 423 00:22:20,200 --> 00:22:23,600 Speaker 1: is you can treat it as a fourth dimension, then 424 00:22:24,400 --> 00:22:27,040 Speaker 1: you know, our experience of the universe is at time 425 00:22:27,480 --> 00:22:33,880 Speaker 1: is constant and the moves at a steady pace, and that, um, 426 00:22:34,240 --> 00:22:36,520 Speaker 1: you're only going forwards in it, right, whereas in space 427 00:22:36,600 --> 00:22:38,719 Speaker 1: you're saying we can go backwards. But what if I 428 00:22:38,800 --> 00:22:41,320 Speaker 1: just kind of take another dimension and use that as 429 00:22:41,320 --> 00:22:44,320 Speaker 1: my kind of ticker? Which dimension would you use as 430 00:22:44,359 --> 00:22:51,240 Speaker 1: your clock? I don't know? Up, okay, yeah, so you'd 431 00:22:51,240 --> 00:22:54,320 Speaker 1: be like, hey, let's have lunch at x equel's five 432 00:22:54,359 --> 00:22:57,119 Speaker 1: meters or something. Yeah, I don't know, or you know, 433 00:22:57,200 --> 00:23:01,119 Speaker 1: kind of mathematically, what does that mean? Different? Time and 434 00:23:01,160 --> 00:23:03,360 Speaker 1: space are not the same. You can't just swap out 435 00:23:03,359 --> 00:23:06,919 Speaker 1: time for space because you don't have the same freedom 436 00:23:06,920 --> 00:23:09,560 Speaker 1: and time as you do in space. Right, if if 437 00:23:09,600 --> 00:23:12,199 Speaker 1: space were moved always forward, the way time did, Like 438 00:23:12,359 --> 00:23:15,720 Speaker 1: you could never go back to anywhere, right, Like, oh yeah, hey, 439 00:23:15,800 --> 00:23:18,000 Speaker 1: I had lunch and now is sort of sliding slowly 440 00:23:18,040 --> 00:23:20,880 Speaker 1: away from me. You know, Um, it would be pretty weird, 441 00:23:21,359 --> 00:23:23,560 Speaker 1: but it's very natural experience. So I see you're more 442 00:23:23,680 --> 00:23:27,159 Speaker 1: limited in the time dimension exactly. There's some extra rules 443 00:23:27,160 --> 00:23:29,200 Speaker 1: that seemed to apply to the time dimension that don't 444 00:23:29,200 --> 00:23:32,920 Speaker 1: apply to the other dimensions. And that's weird. And anytime 445 00:23:33,000 --> 00:23:35,680 Speaker 1: we see symmetries where like cool. But then when those 446 00:23:35,680 --> 00:23:38,199 Speaker 1: symmetries are broken, we're like, Okay, time is like the 447 00:23:38,240 --> 00:23:41,520 Speaker 1: other dimensions, but it's different. Then we ask why is 448 00:23:41,560 --> 00:23:43,760 Speaker 1: it different? How the different? What makes it different? Because 449 00:23:43,800 --> 00:23:47,080 Speaker 1: that's the clue to solve that, not the other puzzle. Right, Okay, 450 00:23:47,119 --> 00:23:49,240 Speaker 1: so time is it is sort of a fourth dimension, 451 00:23:49,320 --> 00:23:52,119 Speaker 1: but there are special rules that apply to it that 452 00:23:52,160 --> 00:23:55,280 Speaker 1: makes us think that maybe it's not really a fourth dimension. 453 00:23:55,320 --> 00:24:01,080 Speaker 1: Maybe it's just like a mathematical um good cluage, right, yeah, 454 00:24:01,240 --> 00:24:04,040 Speaker 1: Or maybe there's two kinds of dimensions. There are space 455 00:24:04,080 --> 00:24:08,040 Speaker 1: dimensions and time dimensions, right, and yeah, and maybe there 456 00:24:08,040 --> 00:24:12,800 Speaker 1: are other people haven't imagined yet, you know. Yeah, that's 457 00:24:12,840 --> 00:24:15,119 Speaker 1: that's the kind of mind blowing, like look at the 458 00:24:15,200 --> 00:24:17,440 Speaker 1: universe in a different way, discovery that I always hope 459 00:24:17,440 --> 00:24:19,439 Speaker 1: to make in science, you know, to like crack something 460 00:24:19,480 --> 00:24:22,040 Speaker 1: open that's so deep that it like nobody gets it 461 00:24:22,080 --> 00:24:32,360 Speaker 1: but the stoner's man. Okay, so, so what are these rules? 462 00:24:32,400 --> 00:24:34,560 Speaker 1: The rules are that you can only you can't visit 463 00:24:34,840 --> 00:24:37,840 Speaker 1: two times in your you know, you can't go back 464 00:24:37,840 --> 00:24:40,400 Speaker 1: in time, you can make gloops, and it can only 465 00:24:40,440 --> 00:24:45,040 Speaker 1: go forward. Are those mainly the main restrictions here with time? Yeah, exactly, 466 00:24:45,080 --> 00:24:47,240 Speaker 1: those are the main restrictions. And I think the goal 467 00:24:47,440 --> 00:24:49,879 Speaker 1: of physics and the goal of our podcast is is 468 00:24:49,920 --> 00:24:52,320 Speaker 1: to try to understand where that comes from. Like can 469 00:24:52,400 --> 00:24:54,919 Speaker 1: we look at the laws of physics and say, oh, 470 00:24:54,960 --> 00:24:57,359 Speaker 1: that comes from this, you know, like the way we 471 00:24:57,359 --> 00:24:59,360 Speaker 1: can look at the laws of quantum mechanics and from 472 00:24:59,359 --> 00:25:01,960 Speaker 1: that understand in the way hydrogen works or whatever. We 473 00:25:02,000 --> 00:25:04,000 Speaker 1: want to look at the laws of physics and say 474 00:25:04,200 --> 00:25:07,399 Speaker 1: do they require this behavior? Is it necessary? What does 475 00:25:07,440 --> 00:25:09,840 Speaker 1: it come from? And it's the deepest level, right. The 476 00:25:09,880 --> 00:25:12,240 Speaker 1: problem is when we look at the laws of physics, 477 00:25:12,480 --> 00:25:14,760 Speaker 1: we don't get those kinds of clues. When when we 478 00:25:14,800 --> 00:25:17,160 Speaker 1: look at the laws of physics, we don't so the 479 00:25:17,240 --> 00:25:21,639 Speaker 1: equations in your model of the universe don't tell you 480 00:25:21,680 --> 00:25:23,840 Speaker 1: that there should be restriction some time. Yeah, let's go 481 00:25:23,880 --> 00:25:26,320 Speaker 1: back to those equations about like the ball moving. Right. 482 00:25:26,760 --> 00:25:32,720 Speaker 1: Imagine you throw a ball, right, you're talking about basic stuff, Right, 483 00:25:32,920 --> 00:25:34,720 Speaker 1: you throw a ball in the air, it goes up 484 00:25:34,800 --> 00:25:37,360 Speaker 1: and it comes down. Let's start with the simplest case 485 00:25:37,400 --> 00:25:39,760 Speaker 1: with there's no air resistance, Right, it's passed up and 486 00:25:39,800 --> 00:25:41,960 Speaker 1: it's passed down. Are gonna be very similar. In fact, 487 00:25:42,200 --> 00:25:45,560 Speaker 1: if somebody took a video of that and then plated backwards, 488 00:25:46,040 --> 00:25:49,399 Speaker 1: they couldn't tell whether the video is going forwards or backwards. Right, 489 00:25:49,440 --> 00:25:52,600 Speaker 1: Physicists analyzing the motion of the ball couldn't tell you 490 00:25:52,640 --> 00:25:56,360 Speaker 1: whether the video was going forwards or backwards. So if 491 00:25:56,400 --> 00:25:59,880 Speaker 1: you fed it a time, like if you gave it time, 492 00:26:00,320 --> 00:26:02,400 Speaker 1: it would give you the same oppu whether you put 493 00:26:02,440 --> 00:26:05,360 Speaker 1: negative time or positive time exactly how it breaks down 494 00:26:05,600 --> 00:26:08,840 Speaker 1: exactly because the equations work in both directions. Right. The 495 00:26:08,840 --> 00:26:11,440 Speaker 1: equations have time in them. They tell you how things 496 00:26:11,520 --> 00:26:15,280 Speaker 1: change with time, but they work the same forwards and backwards. 497 00:26:15,280 --> 00:26:18,359 Speaker 1: So they don't tell you which way the universe should run, right, 498 00:26:18,440 --> 00:26:21,359 Speaker 1: They tell you how the universe changes with time, but 499 00:26:21,400 --> 00:26:23,359 Speaker 1: they don't say why it has to go forwards and 500 00:26:23,440 --> 00:26:25,560 Speaker 1: not backwards, why it has to go anywhere at all? 501 00:26:25,680 --> 00:26:29,000 Speaker 1: Or I can't go forwards and then backwards. Right, So 502 00:26:29,119 --> 00:26:31,880 Speaker 1: if the equations of the universe really represent the universe, 503 00:26:32,560 --> 00:26:37,080 Speaker 1: then the universe would is okay with traveling backwards and time. 504 00:26:37,160 --> 00:26:39,760 Speaker 1: You're saying exactly, the equations sort of saying like, hey, 505 00:26:39,800 --> 00:26:41,440 Speaker 1: you want to go backward this time, Sure, here is 506 00:26:41,480 --> 00:26:44,600 Speaker 1: what would happen. Yeah, exactly, And it's sort of like 507 00:26:44,600 --> 00:26:46,600 Speaker 1: you were saying earlier. It's like an input. You know. 508 00:26:46,640 --> 00:26:49,600 Speaker 1: Imagine you're doing some calculation and the calculation is a 509 00:26:49,640 --> 00:26:52,960 Speaker 1: function of position and time. Right, you want to know 510 00:26:53,520 --> 00:26:55,919 Speaker 1: how many balls are at this location at this time. Right, 511 00:26:56,080 --> 00:26:58,080 Speaker 1: you you drop a thousand balls into a box and 512 00:26:58,080 --> 00:27:00,359 Speaker 1: you're wondering, like, how many balls are this location the time? 513 00:27:00,640 --> 00:27:02,600 Speaker 1: You can ask that question of any point in space, 514 00:27:02,640 --> 00:27:05,000 Speaker 1: at any point in time. Right. You can take the 515 00:27:05,040 --> 00:27:08,320 Speaker 1: concercurrent configuration and you can evolve it forwards or evolve 516 00:27:08,320 --> 00:27:11,000 Speaker 1: it backwards. The laws allow for all of that, but 517 00:27:11,080 --> 00:27:14,280 Speaker 1: for some reason that there there's a difference in the 518 00:27:14,280 --> 00:27:16,640 Speaker 1: way it actually works in the real world. Right, things 519 00:27:16,680 --> 00:27:19,439 Speaker 1: slide forwards in time, and we don't know why. But 520 00:27:19,640 --> 00:27:22,280 Speaker 1: there's no restriction on the space parts right there. The 521 00:27:22,560 --> 00:27:25,280 Speaker 1: equations are functions of space and time, but there's is 522 00:27:25,280 --> 00:27:28,040 Speaker 1: like extra restriction on the time part of it. When 523 00:27:28,040 --> 00:27:31,840 Speaker 1: it comes to like actually implementing the universe, right, it's 524 00:27:31,880 --> 00:27:34,280 Speaker 1: kind of like, um, we have them now, and if 525 00:27:34,320 --> 00:27:37,280 Speaker 1: all we had was now, the equations would let us 526 00:27:38,320 --> 00:27:41,400 Speaker 1: tell what happened before in negative time, and we would 527 00:27:41,440 --> 00:27:44,320 Speaker 1: let it tell us what happens forwards in time, right, 528 00:27:44,720 --> 00:27:49,120 Speaker 1: exactly the equations. Yeah, but but someh our experience. We 529 00:27:49,400 --> 00:27:52,640 Speaker 1: only have experience of the stuff that happened in negative time. 530 00:27:52,760 --> 00:27:55,159 Speaker 1: That's right. We only remember the past, right, that's the 531 00:27:55,200 --> 00:27:58,199 Speaker 1: weird part, right, The past we can remember, we have 532 00:27:58,280 --> 00:28:01,480 Speaker 1: access to it. Um in a affects us. The future 533 00:28:01,560 --> 00:28:04,520 Speaker 1: we can't. And and and most of the laws of 534 00:28:04,520 --> 00:28:07,520 Speaker 1: physics is an asterisk there. Most of the laws of 535 00:28:07,560 --> 00:28:10,240 Speaker 1: physics are totally symmetric. Right. They don't care whether the 536 00:28:10,280 --> 00:28:12,919 Speaker 1: universe is going forward or backwards. They're happy to do 537 00:28:13,000 --> 00:28:18,080 Speaker 1: either one. Wow. So that's the mystery is the time 538 00:28:18,080 --> 00:28:20,800 Speaker 1: would be sort of a fourth dimension, but there's some rules, 539 00:28:20,840 --> 00:28:23,080 Speaker 1: but they those worlds are sort of not in the 540 00:28:23,119 --> 00:28:26,720 Speaker 1: equations of the universe. That's the game with an asterisk, 541 00:28:26,760 --> 00:28:30,960 Speaker 1: you're saying, right, Yeah, So the game is figure out 542 00:28:31,160 --> 00:28:33,240 Speaker 1: if the laws of physics that we know of, that 543 00:28:33,280 --> 00:28:36,760 Speaker 1: we've discovered, that we've written down, if those require things 544 00:28:36,840 --> 00:28:39,959 Speaker 1: to move forwards? Um? And if so, you know, does 545 00:28:40,000 --> 00:28:42,160 Speaker 1: that give us a clues to why it's happening? Or 546 00:28:42,200 --> 00:28:44,200 Speaker 1: maybe there are other laws of physics out there that 547 00:28:44,240 --> 00:28:46,560 Speaker 1: are much more sensage to time, that are the ones 548 00:28:46,640 --> 00:28:48,880 Speaker 1: making time go forward. What do you mean, Like, so 549 00:28:48,920 --> 00:28:51,520 Speaker 1: you're looking for something in the equations that would require 550 00:28:51,960 --> 00:28:55,479 Speaker 1: time to only move forwards? What does that mean? Like 551 00:28:55,920 --> 00:28:59,160 Speaker 1: if you put negative time, you should break or or 552 00:28:59,680 --> 00:29:02,680 Speaker 1: yeah exactly, Like let's think about that. Are there is 553 00:29:02,720 --> 00:29:06,240 Speaker 1: there anything in physics that does require time to move forward? 554 00:29:06,440 --> 00:29:08,760 Speaker 1: So let's go back to that ball example. Right, I said, 555 00:29:08,800 --> 00:29:10,880 Speaker 1: if you throw a ball in the air, Um, you 556 00:29:10,960 --> 00:29:13,240 Speaker 1: can't tell whether the video of that ball in the 557 00:29:13,240 --> 00:29:15,640 Speaker 1: air goes forwards or backwards. And when we did that, 558 00:29:15,680 --> 00:29:18,440 Speaker 1: I said, ignore air resistance. And that's for an important reason, right, 559 00:29:18,480 --> 00:29:21,440 Speaker 1: because air resistance changes the flight of the ball, right, 560 00:29:21,560 --> 00:29:24,400 Speaker 1: slows it down, so that in reality, if you throw 561 00:29:24,440 --> 00:29:27,200 Speaker 1: a ball in the air, right, Um, it's going to 562 00:29:27,280 --> 00:29:29,520 Speaker 1: slow down. And so you can tell the difference between 563 00:29:29,520 --> 00:29:32,840 Speaker 1: going forwards and going backwards right, right, because there's a 564 00:29:33,000 --> 00:29:35,479 Speaker 1: there's like you lose some heat or you lose some 565 00:29:35,560 --> 00:29:38,280 Speaker 1: energy in reality, right. Yeah, it's probably similar to think 566 00:29:38,280 --> 00:29:40,840 Speaker 1: about like dropping a ball. You know, if you drop 567 00:29:40,880 --> 00:29:43,000 Speaker 1: a ball and there's no friction, it's going to come 568 00:29:43,040 --> 00:29:45,600 Speaker 1: all the way up to where where you dropped it from. 569 00:29:45,720 --> 00:29:47,719 Speaker 1: If you drop a ball, it is air resistance. It's 570 00:29:47,760 --> 00:29:51,719 Speaker 1: gonna lose some energy to bumping against all the air molecules. Right, 571 00:29:51,760 --> 00:29:53,600 Speaker 1: It's not gonna come up quite as high as you 572 00:29:53,680 --> 00:29:55,880 Speaker 1: dropped it. You just keep letting it bounce. Eventually it's 573 00:29:56,040 --> 00:29:59,400 Speaker 1: it's gonna dribble down and stop right right. And that one, 574 00:29:59,600 --> 00:30:01,320 Speaker 1: that one to you played it backwards, you would be 575 00:30:01,320 --> 00:30:03,640 Speaker 1: able to tell the difference exactly that one if you 576 00:30:03,640 --> 00:30:05,800 Speaker 1: played backwards. And that's the case for most things, right. 577 00:30:05,800 --> 00:30:09,760 Speaker 1: So where does that come from? Well, that comes from entropy, right, 578 00:30:09,800 --> 00:30:13,040 Speaker 1: that comes from heat. The heat really there is the key. 579 00:30:13,200 --> 00:30:16,720 Speaker 1: It turns out that the universe likes to go from 580 00:30:17,080 --> 00:30:22,280 Speaker 1: organized to disorganized, right, And that's this concept we call entropy. Yeah, 581 00:30:22,360 --> 00:30:24,560 Speaker 1: I've heard of this before, but before we dive in. 582 00:30:24,760 --> 00:30:39,440 Speaker 1: Let's take a short break. What do you mean when 583 00:30:39,480 --> 00:30:43,000 Speaker 1: you say that the universe likes entropy or that it 584 00:30:43,160 --> 00:30:45,920 Speaker 1: likes to go from order to disorder? What is it? 585 00:30:46,000 --> 00:30:47,800 Speaker 1: What is it liking? Me? It means that if the 586 00:30:47,880 --> 00:30:50,120 Speaker 1: universe had a bedroom, it would be a mess, right, 587 00:30:50,560 --> 00:30:54,640 Speaker 1: and it would never want to clean it up. No, 588 00:30:54,800 --> 00:30:57,000 Speaker 1: it's obviously that is our experience of it. Like, maybe 589 00:30:57,000 --> 00:30:59,240 Speaker 1: what if there are aliens out there who experienced time 590 00:30:59,280 --> 00:31:02,520 Speaker 1: backwards and they're like, why does the universe like order? 591 00:31:03,120 --> 00:31:06,000 Speaker 1: Everything we see? It seems to get ordered exactly. So 592 00:31:06,040 --> 00:31:08,000 Speaker 1: there's a big flaw in this argument. But let's put 593 00:31:08,000 --> 00:31:09,480 Speaker 1: a pin in that and come back to it once 594 00:31:09,480 --> 00:31:11,960 Speaker 1: we've done constructing the argument, then we can take it 595 00:31:12,000 --> 00:31:17,239 Speaker 1: apart um. Yeah, so you're right that the universe likes it. Well, 596 00:31:17,320 --> 00:31:22,520 Speaker 1: it just means that we've noticed, we've observed that disorder increases, right. 597 00:31:22,600 --> 00:31:25,320 Speaker 1: For example, the classic example is you have a box 598 00:31:25,600 --> 00:31:27,600 Speaker 1: and you put put a bunch of gas particles in 599 00:31:27,640 --> 00:31:30,400 Speaker 1: the corner. Right, that's very organized. It's like only one 600 00:31:30,440 --> 00:31:32,560 Speaker 1: way to arrange or a few ways to arrange gas 601 00:31:32,560 --> 00:31:34,960 Speaker 1: particles in the corner. What happens if you run the 602 00:31:34,960 --> 00:31:37,240 Speaker 1: clock forward? If you let that go, Well, if they're 603 00:31:37,280 --> 00:31:40,480 Speaker 1: not totally frozen, they're gonna spread out through the box. Right, 604 00:31:40,960 --> 00:31:43,640 Speaker 1: It's like we pour water onto a surface that spreads 605 00:31:43,680 --> 00:31:48,160 Speaker 1: out things like things tend to go from organized configurations 606 00:31:48,280 --> 00:31:51,160 Speaker 1: to disorganized. And that's just an observation. That's not a 607 00:31:51,200 --> 00:31:55,000 Speaker 1: deep insight into the universe. It says, here's what we've seen. Right. 608 00:31:55,240 --> 00:32:00,160 Speaker 1: You notice that there's a correlation between positive time and 609 00:32:00,600 --> 00:32:04,520 Speaker 1: messiness exactly, And that's called the second law of thermodynamics. Right, 610 00:32:04,560 --> 00:32:07,520 Speaker 1: it says that entropy always increases. Entropy is a measure 611 00:32:07,520 --> 00:32:10,840 Speaker 1: of disorder. Right, So things are basically always spreading out 612 00:32:11,400 --> 00:32:14,120 Speaker 1: and um and getting more diffuse, right, And that's the 613 00:32:14,120 --> 00:32:16,280 Speaker 1: whole universe is doing that, Right, The universe, like on 614 00:32:16,320 --> 00:32:19,440 Speaker 1: a grand scale, is spreading out and getting smoother and 615 00:32:19,520 --> 00:32:21,560 Speaker 1: stuff like that. Is it a law law, like an 616 00:32:21,560 --> 00:32:24,520 Speaker 1: equation or is it more like an observation, Right, It's 617 00:32:24,520 --> 00:32:30,840 Speaker 1: more like we've never seen something good un messy with 618 00:32:31,000 --> 00:32:33,760 Speaker 1: positive time. Yeah, that's that's a great question. It's a 619 00:32:33,760 --> 00:32:36,280 Speaker 1: really deep question. I love that question. I think the 620 00:32:36,280 --> 00:32:39,200 Speaker 1: answer is this, Um, The answer is that it's an observation. 621 00:32:39,320 --> 00:32:42,680 Speaker 1: It's something we've noticed and we've never really seen it broken, 622 00:32:42,720 --> 00:32:45,040 Speaker 1: and so we thought, well, this must be important, so 623 00:32:45,120 --> 00:32:47,360 Speaker 1: let's write that down. Let's call that a law because 624 00:32:47,400 --> 00:32:49,720 Speaker 1: it's something we've noticed happens all the time. Now, you 625 00:32:49,720 --> 00:32:52,520 Speaker 1: can never get broken. Why is that? Does that reveal 626 00:32:52,640 --> 00:32:55,560 Speaker 1: something deeper about the universe? Can we explain that from 627 00:32:55,600 --> 00:32:59,160 Speaker 1: something else? And if you dig into like statistical mechanics, 628 00:32:59,560 --> 00:33:02,520 Speaker 1: you can and derived the second law of thermodynamics from 629 00:33:02,560 --> 00:33:07,400 Speaker 1: simpler assumptions, like if you say every possible configuration of 630 00:33:07,440 --> 00:33:11,280 Speaker 1: the universe has equal probability, then it turns out there 631 00:33:11,320 --> 00:33:15,840 Speaker 1: are more messy probably messy configurations than unmessy ones, right, 632 00:33:15,920 --> 00:33:18,880 Speaker 1: Like there's a thousand ways to have gas particles spread 633 00:33:18,880 --> 00:33:20,920 Speaker 1: out through a box, but there's only a couple ways 634 00:33:20,920 --> 00:33:23,400 Speaker 1: to have them stuck in the corner. So it's just 635 00:33:23,560 --> 00:33:26,960 Speaker 1: more likely to end up with the messy ones because 636 00:33:26,960 --> 00:33:30,680 Speaker 1: there are more messy configurations. But that's sort of a 637 00:33:30,720 --> 00:33:32,520 Speaker 1: cop out. I mean, it's just sort of another way 638 00:33:32,520 --> 00:33:35,200 Speaker 1: to state that, is to say, well, we you can 639 00:33:35,240 --> 00:33:38,040 Speaker 1: call this a deeper understanding, but it's also just like 640 00:33:38,320 --> 00:33:40,320 Speaker 1: a posture that we came up with so that we 641 00:33:40,360 --> 00:33:43,360 Speaker 1: could derive the second law, which we've observed. Right, You're 642 00:33:43,400 --> 00:33:45,440 Speaker 1: you're basically down to the same argument you were saying. 643 00:33:46,800 --> 00:33:49,120 Speaker 1: You're basically saying that the reason we have entropy is 644 00:33:49,160 --> 00:33:52,320 Speaker 1: that when you move forward in times, you go through 645 00:33:52,360 --> 00:33:55,160 Speaker 1: the most likely scenario. But then you can ask, why 646 00:33:55,200 --> 00:33:56,640 Speaker 1: does when you go forward in time do you go 647 00:33:56,720 --> 00:33:59,160 Speaker 1: to the most like exactly, it's just a restatement. Really, 648 00:33:59,280 --> 00:34:02,520 Speaker 1: it's a sort of more fundamental statement of the same 649 00:34:02,600 --> 00:34:07,080 Speaker 1: basic observation that things go from organized to messy, right, 650 00:34:07,640 --> 00:34:12,879 Speaker 1: and um, yeah, exactly. So we were looking for, um, like, 651 00:34:13,160 --> 00:34:15,200 Speaker 1: something in the laws of phasics that told us why 652 00:34:16,080 --> 00:34:18,920 Speaker 1: going forwards in time is is preferred, And you're saying, 653 00:34:19,560 --> 00:34:21,879 Speaker 1: we have this observation that it always does and it's 654 00:34:21,920 --> 00:34:25,719 Speaker 1: somehow related to chaos and order and messiness. That's right, 655 00:34:25,880 --> 00:34:27,359 Speaker 1: And so this is like the only thing we can 656 00:34:27,400 --> 00:34:29,880 Speaker 1: really get our fingers on. You know, everything else in 657 00:34:29,960 --> 00:34:34,279 Speaker 1: physics is time symmetric. And there's another asterisk there. There 658 00:34:34,280 --> 00:34:37,640 Speaker 1: are some things in particle physics which are time asymmetric. 659 00:34:37,920 --> 00:34:40,080 Speaker 1: Those are really really small effects, and we don't really 660 00:34:40,080 --> 00:34:42,719 Speaker 1: think that that can explain the direction of time. Um, 661 00:34:42,760 --> 00:34:44,560 Speaker 1: But we can cover that in a whole other podcast 662 00:34:44,640 --> 00:34:48,000 Speaker 1: topics sometimes, but Basically, entropy is the big one. Entropy 663 00:34:48,040 --> 00:34:50,080 Speaker 1: is the only law that like clearly as you say, 664 00:34:50,120 --> 00:34:53,240 Speaker 1: has a correlation. But that's key. You made this point, 665 00:34:53,400 --> 00:34:55,759 Speaker 1: which I think is very insightful, was that there's a correlation. 666 00:34:55,760 --> 00:34:59,680 Speaker 1: It's not causation, right right, we know they're related, but 667 00:35:00,080 --> 00:35:02,239 Speaker 1: what's the connection between them. That's what you're looking for, 668 00:35:02,360 --> 00:35:05,120 Speaker 1: right exactly. That would be something that explains why time 669 00:35:05,160 --> 00:35:07,520 Speaker 1: can only go forward, right exactly. So if you just 670 00:35:07,560 --> 00:35:09,520 Speaker 1: take the second law and you add it to the 671 00:35:09,520 --> 00:35:11,719 Speaker 1: rest of physics, you can say, okay, there's a correlation 672 00:35:11,800 --> 00:35:15,440 Speaker 1: between time and messiness. So either the universe has to 673 00:35:15,440 --> 00:35:18,600 Speaker 1: go forward in time and get messier, or the universe 674 00:35:18,600 --> 00:35:21,319 Speaker 1: has to go backwards in time and get less messy. Right, 675 00:35:21,880 --> 00:35:24,960 Speaker 1: Either the second law of physics allows for both. Right. 676 00:35:25,239 --> 00:35:28,520 Speaker 1: So it doesn't actually tell you why time goes forwards. 677 00:35:28,800 --> 00:35:31,560 Speaker 1: It just says, well, if you pick forwards, then this 678 00:35:31,600 --> 00:35:33,799 Speaker 1: is going to happen. If you pick backwards, that's going 679 00:35:33,840 --> 00:35:36,160 Speaker 1: to happen. And there's a difference. So it breaks the 680 00:35:36,200 --> 00:35:38,279 Speaker 1: symmetry of forward and backwards, but it doesn't pick one. 681 00:35:38,680 --> 00:35:41,440 Speaker 1: Or or if you assume that messiness is kind of 682 00:35:41,480 --> 00:35:44,520 Speaker 1: where the universe prefers to be. Then that tells you 683 00:35:44,560 --> 00:35:49,120 Speaker 1: that forward time is the preferred thing in the universe. Yeah, 684 00:35:49,200 --> 00:35:52,160 Speaker 1: And it doesn't even tell you that entropy determines time, right, 685 00:35:52,200 --> 00:35:53,799 Speaker 1: It just tells you that they're connecting. There could be 686 00:35:53,800 --> 00:35:58,520 Speaker 1: something else, something deeper, which causes both time and entropy. Right, 687 00:35:58,719 --> 00:36:01,480 Speaker 1: that's the whole problem with like correlations. You know, you 688 00:36:01,520 --> 00:36:03,959 Speaker 1: can find correlations between between lots of things. It doesn't 689 00:36:04,000 --> 00:36:07,520 Speaker 1: explain it, right, what's some of those famous things? Like, Um, 690 00:36:07,600 --> 00:36:10,920 Speaker 1: you know global warming is correlated with the decrease in 691 00:36:10,960 --> 00:36:14,640 Speaker 1: the number of piracy events worldwide? Right? Does that mean 692 00:36:14,680 --> 00:36:18,000 Speaker 1: that pirates kept global warming at bay for hundreds of years? Certainly? 693 00:36:18,040 --> 00:36:21,440 Speaker 1: Not right? Um? So we know time and interropy are correlated. 694 00:36:21,640 --> 00:36:24,439 Speaker 1: We don't know if entropy causes time or the other way, 695 00:36:24,560 --> 00:36:27,960 Speaker 1: or something else deeper that we haven't even thought about yet. Um. 696 00:36:28,160 --> 00:36:30,560 Speaker 1: Or maybe it's just random, Like maybe it's a random 697 00:36:30,600 --> 00:36:34,880 Speaker 1: connection like pirates and global warming. I think we've observed 698 00:36:34,960 --> 00:36:37,120 Speaker 1: in grid enough detail that we know it better than 699 00:36:37,120 --> 00:36:40,680 Speaker 1: empirate than global warming. Um. But I love looking at 700 00:36:40,719 --> 00:36:43,480 Speaker 1: these correlations. You know, there's like a correlation between the 701 00:36:43,560 --> 00:36:46,600 Speaker 1: number of movies Nicolas Cage has done and the number 702 00:36:46,600 --> 00:36:49,360 Speaker 1: of people per year that die because they're twisted in 703 00:36:49,400 --> 00:36:56,120 Speaker 1: their own bedsheets. So they're correlated. When one goes up, 704 00:36:56,160 --> 00:36:58,400 Speaker 1: the other one goes up. Yeah, exactly, or they have right, 705 00:36:58,440 --> 00:37:00,879 Speaker 1: that doesn't mean they're going to continue in the few sure, right. 706 00:37:00,880 --> 00:37:03,600 Speaker 1: That's the problem with the observational correlations they don't tell 707 00:37:03,600 --> 00:37:05,799 Speaker 1: you is if you don't understand the mechanism of it, 708 00:37:06,080 --> 00:37:09,040 Speaker 1: you can't really argue that they're connected. They could just 709 00:37:09,080 --> 00:37:12,840 Speaker 1: be chance. Right, Um, I mean sometimes there are connections, 710 00:37:12,920 --> 00:37:15,960 Speaker 1: Like you know that the consumption of ice cream is 711 00:37:16,040 --> 00:37:20,040 Speaker 1: very well correlated with the number of murders. What. Yeah, 712 00:37:20,080 --> 00:37:22,200 Speaker 1: Well people kill people more in the summer, I guess 713 00:37:22,200 --> 00:37:25,839 Speaker 1: because they're grumpier and they're sweaty and hot. People also 714 00:37:26,040 --> 00:37:29,120 Speaker 1: ice cream in the summer. Right, So say some rude 715 00:37:29,120 --> 00:37:32,000 Speaker 1: cause cause is in charge of both ice cream consumption 716 00:37:32,239 --> 00:37:35,319 Speaker 1: and murder rates. Right. It doesn't mean that ice cream 717 00:37:35,360 --> 00:37:38,399 Speaker 1: causes murder, right that we know of that we know 718 00:37:39,080 --> 00:37:42,240 Speaker 1: don't understand everything. That's right, the fourth law of thermodynamics, 719 00:37:42,280 --> 00:37:51,319 Speaker 1: ice cream causes murder? Um? Okay, So entropies are only 720 00:37:51,400 --> 00:37:54,720 Speaker 1: kind of clue you're saying, And there's three possibilities. Either 721 00:37:55,440 --> 00:38:01,400 Speaker 1: time an entropy are not at all connected. They just 722 00:38:01,440 --> 00:38:05,239 Speaker 1: haven't to go in the same direction, or they are 723 00:38:06,200 --> 00:38:09,000 Speaker 1: both the result of something else deeper about the universe, 724 00:38:09,239 --> 00:38:14,799 Speaker 1: or maybe one causes the other or right, yeah, exactly 725 00:38:14,400 --> 00:38:16,040 Speaker 1: direct connect and we don't know and we don't even 726 00:38:16,080 --> 00:38:17,480 Speaker 1: know if there is much of a connection. And if 727 00:38:17,520 --> 00:38:19,480 Speaker 1: you know, there's a lot of deep questions. They're like 728 00:38:19,520 --> 00:38:23,880 Speaker 1: if time is because of entropy, then like what happens 729 00:38:24,239 --> 00:38:27,719 Speaker 1: when the universe reaches maximum entropy, because you know, if 730 00:38:27,840 --> 00:38:30,839 Speaker 1: entropy is always increasing and time is going forwards, then 731 00:38:30,880 --> 00:38:34,000 Speaker 1: there's no rewind right, the universe marches forward towards messier 732 00:38:34,000 --> 00:38:36,960 Speaker 1: and messier, and eventually you reach the heat death of 733 00:38:36,960 --> 00:38:40,960 Speaker 1: the universe when everything is perfectly spread out, right, perfectly disorganized, 734 00:38:40,960 --> 00:38:44,800 Speaker 1: there's no structures at all. Does time stop? Does time 735 00:38:44,840 --> 00:38:47,680 Speaker 1: turn around and go the other way? Like, you know, 736 00:38:47,920 --> 00:38:50,680 Speaker 1: just saying time is connected entropy doesn't answer most of 737 00:38:50,719 --> 00:38:56,800 Speaker 1: the deepest questions Time quit exactly. Some people have theories 738 00:38:56,800 --> 00:39:00,400 Speaker 1: that time stops and turns around, right, and the universe 739 00:39:00,440 --> 00:39:04,960 Speaker 1: then goes towards more organized configurations like maybe, um, I 740 00:39:05,000 --> 00:39:07,720 Speaker 1: love reading about theories of time because people really go bonkers. 741 00:39:07,960 --> 00:39:10,879 Speaker 1: One of my favorites is that is a guy who 742 00:39:10,880 --> 00:39:14,239 Speaker 1: asked the question, Okay, we have three or more dimensions 743 00:39:14,239 --> 00:39:19,359 Speaker 1: of space, why should we have only one dimension of time? Right? Like, 744 00:39:19,400 --> 00:39:22,840 Speaker 1: what if you had two dimensions of time? That's pretty 745 00:39:22,840 --> 00:39:25,040 Speaker 1: hard to think about, which is weird because it's not 746 00:39:25,120 --> 00:39:26,799 Speaker 1: so hard to think about two dimensions of space to 747 00:39:26,800 --> 00:39:29,000 Speaker 1: think about like you know, a plane instead of a line, 748 00:39:29,360 --> 00:39:32,000 Speaker 1: but it's pretty hard to think about two dimensions of time, 749 00:39:32,160 --> 00:39:35,040 Speaker 1: like I'll meet you at three o'clock in north and 750 00:39:35,560 --> 00:39:38,880 Speaker 1: you know four fifteen east west? Like what does that 751 00:39:38,920 --> 00:39:42,080 Speaker 1: even mean? What is before and after? Right? Oh? You 752 00:39:42,080 --> 00:39:45,240 Speaker 1: could have time coordinates? Yeah, yeah, you could have multiple 753 00:39:45,280 --> 00:39:48,160 Speaker 1: dimensions of time. Um, isn't that sort of like a 754 00:39:48,280 --> 00:39:53,439 Speaker 1: multiverse argument? Then, like there's maybe parallel universes besides this one. 755 00:39:53,560 --> 00:39:55,160 Speaker 1: Well that's a bit of a cop out, right saying 756 00:39:55,719 --> 00:39:59,080 Speaker 1: maybe there's every configuration and our universe just happens to 757 00:39:59,120 --> 00:40:01,719 Speaker 1: have one core a native time And that's the explanation. 758 00:40:02,360 --> 00:40:04,200 Speaker 1: I think there must be a deep reason. There must 759 00:40:04,239 --> 00:40:07,720 Speaker 1: be a um, something revealing about the structure the universe 760 00:40:07,760 --> 00:40:09,839 Speaker 1: as we've discovered it. There's it's got to be a 761 00:40:09,840 --> 00:40:12,839 Speaker 1: clue as the way the things actually work, you know, 762 00:40:13,000 --> 00:40:15,320 Speaker 1: and I suspect that it's a it's going to be 763 00:40:15,360 --> 00:40:17,439 Speaker 1: a really deep answer that when we figure it out, 764 00:40:17,640 --> 00:40:20,800 Speaker 1: it's gonna show us that the universe works really differently 765 00:40:20,840 --> 00:40:23,480 Speaker 1: from the way we imagined. That a huge parts of 766 00:40:23,520 --> 00:40:25,640 Speaker 1: our life, um, and the way we live and the 767 00:40:25,719 --> 00:40:28,520 Speaker 1: things we think are fundamental about the universe are accidents. 768 00:40:28,520 --> 00:40:33,960 Speaker 1: Are just constructs, right, they are timely accidents. Sorry, it 769 00:40:33,960 --> 00:40:37,080 Speaker 1: took a lot of time, but eventually we we created 770 00:40:37,120 --> 00:40:40,719 Speaker 1: this illusion of the universe. Yeah, alright, so then we 771 00:40:40,719 --> 00:40:43,320 Speaker 1: we haven't really answered the question. I mean, it sounds 772 00:40:43,320 --> 00:40:45,239 Speaker 1: like there is no answer, right, like why does time 773 00:40:45,280 --> 00:40:48,239 Speaker 1: only go forwards? We know it's related to entropy, but 774 00:40:48,280 --> 00:40:50,600 Speaker 1: we don't really know the connection, and that's that's kind 775 00:40:50,600 --> 00:40:51,920 Speaker 1: of as far as we know. I mean, there are 776 00:40:51,920 --> 00:40:53,640 Speaker 1: a lot of people out there thought about this much 777 00:40:53,680 --> 00:40:56,200 Speaker 1: more deeply than I have. Sean Carroll, Carlo Rovelli, these 778 00:40:56,239 --> 00:40:59,560 Speaker 1: folks have written whole books on time. But in my view, 779 00:40:59,800 --> 00:41:02,879 Speaker 1: the argument mostly boils down to, you know, either it's 780 00:41:02,880 --> 00:41:05,719 Speaker 1: connected to entropy, which I don't find that convincing an 781 00:41:05,719 --> 00:41:09,320 Speaker 1: explanation for why it goes forwards, right, or that space 782 00:41:09,320 --> 00:41:11,600 Speaker 1: and time itself are illusions and they come out of 783 00:41:11,680 --> 00:41:14,799 Speaker 1: something deeper and uh, you know, and we need to 784 00:41:14,840 --> 00:41:17,120 Speaker 1: dig deeper to understand like the string theory of the 785 00:41:17,160 --> 00:41:20,160 Speaker 1: universe or the quantum loops that make up the fabric 786 00:41:20,200 --> 00:41:24,840 Speaker 1: of space and time itself. Um, so we were pretty 787 00:41:24,880 --> 00:41:27,080 Speaker 1: pretty clueless as a field. It's a it's a definitely 788 00:41:27,080 --> 00:41:29,520 Speaker 1: an open time. Well until we figure it out. I 789 00:41:29,560 --> 00:41:33,400 Speaker 1: hope that people out there don't lose it and they 790 00:41:33,400 --> 00:41:35,279 Speaker 1: that they make the best use of it. Right. Yeah, 791 00:41:35,440 --> 00:41:37,959 Speaker 1: but it's not a waste of time to think about time. 792 00:41:39,520 --> 00:41:41,839 Speaker 1: It just takes a little bit of time, that's right. 793 00:41:42,160 --> 00:41:44,640 Speaker 1: But it's about time, and now it's time to the 794 00:41:44,719 --> 00:41:47,160 Speaker 1: end the podcast. That's right. So thanks for listening, And 795 00:41:47,200 --> 00:41:50,360 Speaker 1: if you have questions about big, basic fundamental questions of 796 00:41:50,400 --> 00:41:52,839 Speaker 1: the universe, send them to us. We love to dig 797 00:41:52,840 --> 00:41:55,799 Speaker 1: into them and explore our ignorance and the ignorance of 798 00:41:55,840 --> 00:41:58,920 Speaker 1: modern physics. So send us your questions at feedback at 799 00:41:59,160 --> 00:42:03,160 Speaker 1: Daniel and Y dot com. Yeah, thanks for listening. See 800 00:42:03,200 --> 00:42:07,239 Speaker 1: you next time or see you last time. We should say, oh, 801 00:42:07,280 --> 00:42:13,320 Speaker 1: see you last, see you, see you anything, see anytime. 802 00:42:13,400 --> 00:42:24,080 Speaker 1: That's right. Thanks for listening. If you still have a 803 00:42:24,160 --> 00:42:27,600 Speaker 1: question after listening to all these explanations. Please drop us 804 00:42:27,640 --> 00:42:29,719 Speaker 1: a line. We'd love to hear from you. You can 805 00:42:29,760 --> 00:42:33,160 Speaker 1: find us at Facebook, Twitter, and Instagram at Daniel and 806 00:42:33,280 --> 00:42:36,799 Speaker 1: Jorge That's one Word, or email us at Feedback at 807 00:42:36,880 --> 00:42:40,280 Speaker 1: Daniel and Jorge dot com. Thanks for listening, and remember 808 00:42:40,320 --> 00:42:43,160 Speaker 1: that Daniel and Jorge Explain the Universe is a production 809 00:42:43,239 --> 00:42:46,760 Speaker 1: of I Heart Radio from More podcast from my heart Radio, 810 00:42:46,920 --> 00:42:50,480 Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever 811 00:42:50,600 --> 00:42:52,280 Speaker 1: you listen to your favorite shows.