WEBVTT - What is Entropy? 0:00:06.040 --> 0:00:08.800 There are so many topics in physics that are hard 0:00:08.840 --> 0:00:12.719 to grapple with to deeply understand, and it's not helped 0:00:12.760 --> 0:00:16.040 by the fact that often physicists have given these things 0:00:16.160 --> 0:00:20.680 confusing names. Electrons, for example, have quantum spin, but they're 0:00:20.720 --> 0:00:24.640 not actually spinning. Moments of inertia have nothing to do 0:00:24.760 --> 0:00:28.920 with moments of time. Work and power have very different 0:00:28.960 --> 0:00:32.880 meanings in physics and in English. But sometimes even when 0:00:32.920 --> 0:00:36.920 physicists invent a brand new word to convey a new idea, 0:00:37.320 --> 0:00:40.760 it's still slippery to grasp. So today in the pod, 0:00:40.840 --> 0:00:42.640 we're going to try to grab hold of one of 0:00:42.640 --> 0:00:47.040 the trickiest concepts in physics, one that's often tossed about 0:00:47.040 --> 0:00:50.479 and attached to a simple explanation, but whose subtle power 0:00:50.880 --> 0:00:54.280 isn't usually clearly explained. Today in the pod, we are 0:00:54.360 --> 0:00:57.880 tackling entropy. What is it? Does it explain why our 0:00:57.880 --> 0:01:01.200 teenager's rooms are so messy, or why coffee spills out 0:01:01.200 --> 0:01:03.639 of cups but not back into them. Does it tell 0:01:03.720 --> 0:01:06.000 us about the fate of the universe or the nature 0:01:06.000 --> 0:01:09.440 of time? Is it about order and chaos? Why did 0:01:09.480 --> 0:01:14.200 physicists even devise this concept? Welcome to Daniel and Kelly's 0:01:14.319 --> 0:01:17.160 Extraordinarily Disorderly Universe. 0:01:31.160 --> 0:01:34.080 Hello. My name is Kelly Wiener Smith, and I often 0:01:34.080 --> 0:01:37.240 make jokes about entropy increasing in my home, and today 0:01:37.280 --> 0:01:39.920 I'm gonna find out if that joke is scientifically accurate 0:01:40.000 --> 0:01:42.040 or not. Hi. 0:01:42.200 --> 0:01:44.800 I'm Daniel. I'm a particle a physicists, and I think 0:01:44.840 --> 0:01:47.480 that there's always one person in the marriage who's more 0:01:47.560 --> 0:01:49.520 orderly and one person is more chaotic. 0:01:50.960 --> 0:01:54.720 Yeah, it's pretty easy to identify who's who in my marriage. 0:01:55.760 --> 0:01:57.840 Are you the more orderly or the more chaotic in 0:01:57.880 --> 0:02:00.840 your marriage? Katrina seems pretty orderly, but so do you. 0:02:01.240 --> 0:02:03.560 I don't want to slander my wife on air, especially 0:02:03.560 --> 0:02:05.680 if she's not here to defend herself, so I'll say 0:02:05.680 --> 0:02:09.200 that in some categories, I'm more orderly, and in some categories, 0:02:09.480 --> 0:02:11.560 she's more on top of stuff, and that's why we're 0:02:11.600 --> 0:02:12.320 such a good team. 0:02:12.880 --> 0:02:15.320 Ah, I'm going to slander my husband. He's the chaotic 0:02:15.360 --> 0:02:18.360 force in our family, he absolutely is. But he's also, 0:02:18.520 --> 0:02:20.280 you know, a lot of the creative force. So it 0:02:20.320 --> 0:02:20.720 works out. 0:02:20.760 --> 0:02:23.920 Yeah, exactly. Well. The yin and yang is what makes 0:02:23.919 --> 0:02:25.120 it exciting, isn't it. 0:02:25.120 --> 0:02:28.760 It keeps things fresh, that's for sure. So I was 0:02:28.800 --> 0:02:30.799 thinking about the topic for today, and when I think 0:02:30.800 --> 0:02:33.840 about entropy, the first thing that comes to mind is 0:02:33.960 --> 0:02:37.280 jazz music. And when I googled entropy and jazz, actually 0:02:37.280 --> 0:02:39.280 a lot of things came up. People have like studied 0:02:39.320 --> 0:02:42.120 jazz music through the lens of entropy. Do you like 0:02:42.200 --> 0:02:43.280 jazz music? What do you think? 0:02:45.000 --> 0:02:49.040 Wow, that's fascinating. I never connected entropy and jazz music. 0:02:49.520 --> 0:02:52.079 There's some jazz music I like, but I like things 0:02:52.080 --> 0:02:53.960 that are a little bit more melodic. So just like 0:02:54.360 --> 0:02:57.320 a wandering sprinkle of nodes doesn't do it for me. 0:02:57.639 --> 0:02:59.600 I need a little bit of rhythm and some beat 0:02:59.639 --> 0:03:01.440 to it and whatever. So I'm more of a blues 0:03:01.480 --> 0:03:03.000 guy than jazz, how about you. 0:03:03.280 --> 0:03:05.240 It depends on my mood. There are some moods that 0:03:05.280 --> 0:03:07.720 I'm in where jazz is exactly what I want and 0:03:07.760 --> 0:03:09.880 it's exactly what I need to listen to while I'm writing. 0:03:10.200 --> 0:03:12.480 And then there's other moods where it does make me 0:03:12.520 --> 0:03:16.120 feel kind of frustrated and overwhelmed. So, but you know, 0:03:16.200 --> 0:03:17.600 I feel that way for a lot of different kinds 0:03:17.639 --> 0:03:19.840 of music. I've got like very particular kinds of music 0:03:19.880 --> 0:03:20.880 for different kinds of moods. 0:03:21.200 --> 0:03:24.600 I appreciate the jazz nerds though, because they help me 0:03:24.680 --> 0:03:28.040 understand how almost any human endeavor there are so many 0:03:28.120 --> 0:03:30.760 layers to it, you know, like people who appreciate wine 0:03:30.760 --> 0:03:32.400 and they can tell the difference between like a five 0:03:32.520 --> 0:03:34.440 hundred dollars bottle of wine and a five thousand dollars 0:03:34.440 --> 0:03:36.800 bottle of wine, whereas like I can't tell the difference 0:03:36.800 --> 0:03:39.720 between ten dollars and twenty dollars bottles of wine, Or 0:03:39.760 --> 0:03:42.400 like how many levels of skale there are two chess, 0:03:42.680 --> 0:03:44.400 you know, where like a level twenty person will be 0:03:44.440 --> 0:03:47.960 the level eighteen person will be the level seventeen person. Consistently. 0:03:48.080 --> 0:03:50.160 I feel that same way about jazz, because people talk 0:03:50.200 --> 0:03:52.240 about it and they're like, Wow, this guy is a 0:03:52.240 --> 0:03:54.400 genius and so amazing in this way and that way, 0:03:54.440 --> 0:03:56.400 and I'm just like at the beginning of a journey 0:03:56.440 --> 0:03:59.080 of appreciating that. But I love when human culture goes 0:03:59.160 --> 0:04:02.800 really deep on something and people could appreciate the fine 0:04:02.880 --> 0:04:03.680 nuances of it. 0:04:04.080 --> 0:04:06.040 Yeah, you know, if I had endless time and money, 0:04:06.040 --> 0:04:08.320 I would love to just like jump into different cultures 0:04:08.400 --> 0:04:11.680 and just sort of like appreciate and absorb, you know, 0:04:11.720 --> 0:04:14.320 the various features that are exciting to them and just 0:04:14.360 --> 0:04:16.600 sort of enjoy their culture for a little while. And 0:04:17.120 --> 0:04:19.640 I very briefly jumped into jazz as I've had different 0:04:19.680 --> 0:04:22.560 friends who do jazz things and it's a very cool culture. 0:04:22.680 --> 0:04:24.680 But I am still at the early phases of like 0:04:24.920 --> 0:04:26.520 what is good? I don't know. I just know that 0:04:26.600 --> 0:04:27.480 this makes me smile. 0:04:29.720 --> 0:04:32.040 Well, something I do have very strong opinions about because 0:04:32.040 --> 0:04:35.200 I spent a lot of time perfecting my tastes about 0:04:35.200 --> 0:04:37.719 it is pizza making. I'm an at home pizza maker, 0:04:38.000 --> 0:04:39.960 and I have like strong opinions about like, you know, 0:04:39.960 --> 0:04:42.240 the stretchiness of the dough and the puffiness of the 0:04:42.240 --> 0:04:45.520 crust and the darkness of the sauce and whatever, because 0:04:45.800 --> 0:04:47.760 I've made a lot of pizzas in my house, so 0:04:47.800 --> 0:04:50.000 I know like exactly what I like in a pizza. 0:04:50.240 --> 0:04:52.800 What have you nerded out on? What are you like 0:04:52.800 --> 0:04:54.359 a level twenty expert in? 0:04:54.880 --> 0:04:57.600 Hmm? Well, so first I'll say that my husband also 0:04:57.680 --> 0:04:59.599 nerds out on pizza, which is making me wonder if 0:04:59.640 --> 0:05:02.200 we sh make pizza when you're here to visit or 0:05:02.240 --> 0:05:05.800 if we shouldn't. Uh oh, Zach and I will have 0:05:05.839 --> 0:05:08.360 a discussion about that. What am I a level twenty 0:05:08.400 --> 0:05:11.760 nerd on. I don't know. I guess I'm sort of 0:05:11.800 --> 0:05:14.520 a generalist. I like lots of things. I mean, I'm 0:05:14.520 --> 0:05:17.640 really into the moths in our area, and I spent 0:05:17.680 --> 0:05:21.359 two years learning about Russian and Russian culture and like 0:05:21.440 --> 0:05:23.640 the language. But I don't know if I'm like a 0:05:23.720 --> 0:05:25.719 level twenty on either one. 0:05:25.600 --> 0:05:28.359 Of those things. Well, I can tell you moths not 0:05:28.480 --> 0:05:30.919 very good on pizza. I mean they're delicious, but really 0:05:30.960 --> 0:05:31.920 not a popular topic. 0:05:32.120 --> 0:05:34.960 No, I totally believe that. But I've pulled us far 0:05:35.040 --> 0:05:39.719 from our topic. Today. We're talking about entropy, and you know, 0:05:39.760 --> 0:05:41.800 I think first we should find out what our audience 0:05:41.960 --> 0:05:43.119 thinks entropy means. 0:05:43.320 --> 0:05:45.040 That's right, let's try to beat back the chaos and 0:05:45.080 --> 0:05:49.000 stay on topic today, Kelly good luck. So I went 0:05:49.040 --> 0:05:52.200 out there and I asked folks what they thought entropy was, 0:05:52.240 --> 0:05:54.560 because I was curious what connections people had made in 0:05:54.600 --> 0:05:57.359 their minds. Maybe they'll also connect it to jazz or 0:05:57.400 --> 0:06:00.880 blues or pizza making or moth loving. Let's hear what 0:06:00.960 --> 0:06:04.359 folks had to say. The tendency of a closed system 0:06:04.440 --> 0:06:08.080 to kind of go from order to disorder unless you 0:06:08.120 --> 0:06:11.599 add energy to go from order to disorder only I 0:06:11.720 --> 0:06:12.720 had my head around it. 0:06:13.279 --> 0:06:16.279 Entropy is a measure of the remaining free energy in 0:06:16.320 --> 0:06:17.560 a specific. 0:06:17.080 --> 0:06:22.679 Volume homogene as milk toast, a description of the state 0:06:22.720 --> 0:06:25.840 of a system in terms of its energy. The more 0:06:26.040 --> 0:06:29.359 different configurations the system can have and be in the 0:06:29.400 --> 0:06:34.799 same state, the higher the entropy it has. Matter being 0:06:35.640 --> 0:06:39.520 either organized or being in a chaotic state, the degree 0:06:39.560 --> 0:06:42.359 of disorder and a physical system. 0:06:41.880 --> 0:06:44.719 The amount of energy in a system that can't. 0:06:44.560 --> 0:06:47.120 Be recovered, describes the level of organization. 0:06:47.320 --> 0:06:49.640 As time progresses, entropy progresses. 0:06:49.839 --> 0:06:52.640 I think it's the tendency of energy to spread out 0:06:53.160 --> 0:06:58.599 slow crawl towards simplicity that the universe imposes on everything. Disorder, 0:06:59.240 --> 0:07:04.080 aos the absence of order. Things degrade over time. It 0:07:04.160 --> 0:07:06.880 feels weird because that seems made up what disorder is 0:07:06.920 --> 0:07:09.480 and what order is. Or if there are more configurations, 0:07:09.520 --> 0:07:13.400 the entropy is higher number of micro states of the system, 0:07:13.640 --> 0:07:15.920 which can result in the current macro state. 0:07:16.080 --> 0:07:18.880 Things want to move from a higher embodied energy state 0:07:19.240 --> 0:07:22.360 to a lower one. Well, no pizza in those answers, 0:07:22.360 --> 0:07:24.920 but actually a lot of variety in the answers there. 0:07:25.080 --> 0:07:27.720 Yeah, I think we really capture something here that there's 0:07:27.760 --> 0:07:30.680 a general sense that entropy goes up and that it 0:07:30.760 --> 0:07:33.640 has to do something with order and disorder, but also 0:07:33.680 --> 0:07:36.840 that there are multiple concepts of entropy. Right, this sensitive 0:07:37.040 --> 0:07:40.280 energy and entropy and a sense of organization related to entropy. 0:07:40.880 --> 0:07:43.320 And so I think that captures like the big chaotic 0:07:43.360 --> 0:07:47.600 confusion that is most people's understanding of what entropy actually is. 0:07:48.000 --> 0:07:50.520 I do think this idea has escaped into like the 0:07:50.720 --> 0:07:54.680 general consciousness, and maybe it has disconnected from its physics 0:07:54.680 --> 0:07:56.400 definitions in that process. 0:07:56.640 --> 0:07:58.119 Yeah, I think you see a lot of tech bros 0:07:58.160 --> 0:08:01.040 on social media using enterpa if they know what it means. 0:08:03.480 --> 0:08:05.720 I mean, it's nowhere near as bad as the word quantum. 0:08:05.720 --> 0:08:07.880 But let's clear things up today exactly. 0:08:08.280 --> 0:08:09.240 It's getting there, though. 0:08:09.280 --> 0:08:11.720 It's getting there, all right. So tell me about the 0:08:11.720 --> 0:08:13.800 first time the word entropy was used. 0:08:14.040 --> 0:08:16.760 Yeah, entropy is a fun topic because it's not an 0:08:16.800 --> 0:08:20.120 ancient topic. Right. People have been talking about motion and 0:08:20.200 --> 0:08:23.640 velocity and energy and time since people have been like 0:08:23.720 --> 0:08:26.160 smoking whatever and sitting in caves and looking up at 0:08:26.160 --> 0:08:28.440 the night sky and wondering how the universe. 0:08:28.040 --> 0:08:29.920 Works, the things that bring us all together. 0:08:30.800 --> 0:08:33.000 Yeah, so you can go back and look at the 0:08:33.160 --> 0:08:36.200 Sumerians thinking about the path of the planets and the 0:08:36.280 --> 0:08:38.559 length of the year, and you know, the structure of 0:08:38.600 --> 0:08:40.920 the Solar system and stuff like that. But entropy is 0:08:40.960 --> 0:08:44.520 a recent concept. It's less than two hundred years old. 0:08:44.760 --> 0:08:48.120 It's a word that was invented fairly recently as people 0:08:48.160 --> 0:08:51.760 were puzzling over engines and wheels and energy. 0:08:52.160 --> 0:08:54.000 Oh so was the idea that, like, it's hard to 0:08:54.080 --> 0:08:58.280 keep an engine working because entropy sort of overtime makes 0:08:58.320 --> 0:09:01.760 the system less reliable or tell me more about this history. 0:09:01.960 --> 0:09:04.360 Yes, so it's the early eighteen hundreds and there's the 0:09:04.440 --> 0:09:08.640 Carnea cycle and so this French physicist Carno actually a 0:09:08.679 --> 0:09:12.440 father's son team we're thinking about engines and heat and 0:09:12.480 --> 0:09:14.160 there was sort of a mystery at the time, like 0:09:14.360 --> 0:09:17.640 what is heat? Anyway, people had the sense that the 0:09:17.760 --> 0:09:21.040 universe had a microscopic explanation that could help you understand 0:09:21.080 --> 0:09:24.000 the macroscopic view, like you know, this is around the 0:09:24.080 --> 0:09:26.840 time when we're about to get Dalton and thinking about 0:09:26.840 --> 0:09:29.840 the existence of atoms. So that idea is out there 0:09:29.840 --> 0:09:32.760 that like maybe this microscopic stuff, you know, and also 0:09:32.760 --> 0:09:35.400 biologically right, like the germ theory is coming out around 0:09:35.480 --> 0:09:38.600 this time, you know, within decades at least, so people 0:09:38.600 --> 0:09:41.960 were wondering, like, what is heat? Is heat like a particle, 0:09:42.160 --> 0:09:44.559 is it a substance? Does it flow from one thing 0:09:44.600 --> 0:09:47.559 to the other. Remember early ideas of like electric charge, 0:09:47.800 --> 0:09:49.520 where like there were two of them and they were 0:09:49.520 --> 0:09:51.760 a liquid and they flowed. So this is sort of 0:09:51.760 --> 0:09:54.040 like an idea that was out there. People were wondering, 0:09:54.320 --> 0:09:57.080 how do engines work? What is energy? What is heat? 0:09:57.120 --> 0:09:59.319 How are they all related? And in eighteen twenty four 0:09:59.360 --> 0:10:02.680 Carnot put his finger on this idea that differences in 0:10:02.760 --> 0:10:06.160 heat can be used to do useful stuff like if 0:10:06.200 --> 0:10:08.920 you have something that's hot and something that's cold, energy 0:10:08.920 --> 0:10:10.800 will flow from the hot thing to the cold thing, 0:10:10.960 --> 0:10:13.800 and you can use that to do stuff sort of 0:10:13.840 --> 0:10:17.280 like the way water flows from uphill to downhill, and 0:10:17.320 --> 0:10:20.240 if you capture that flow, you put like a water 0:10:20.280 --> 0:10:22.680 wheel there. You can use that to do stuff like 0:10:22.880 --> 0:10:26.920 grind your wheat into flour. Right, very useful. But if 0:10:26.920 --> 0:10:28.640 the water is all flat, you can't use it to 0:10:28.679 --> 0:10:31.480 do anything. And so heat differences can be used to 0:10:31.559 --> 0:10:34.760 produce work. That's Carno's big insight in the early eighteen. 0:10:34.559 --> 0:10:37.360 Hundreds, did we have the steam engine at this point. 0:10:37.440 --> 0:10:40.240 Yet, yeah, steam engines existed at this point, and that's 0:10:40.280 --> 0:10:42.400 a great example of how you use heat. Right, you 0:10:42.440 --> 0:10:45.400 heat the steam, it rises, it turns your turbine. You 0:10:45.440 --> 0:10:47.440 can use that to do work or these days to 0:10:47.600 --> 0:10:52.559 make electricity. Right, and so Carne understood that engines can 0:10:52.600 --> 0:10:56.320 do this, engines can turn heat differences into work. But 0:10:56.400 --> 0:10:59.200 he describes sort of a perfect engine one where you 0:10:59.240 --> 0:11:02.080 can turn heat differences into work, and then you could 0:11:02.200 --> 0:11:04.600 use that work to create heat differences, so back and 0:11:04.640 --> 0:11:07.040 forth and back and forth and sort of perfectly without 0:11:07.040 --> 0:11:10.040 any loss. But he also had this idea that, well, 0:11:10.120 --> 0:11:14.840 sometimes you have imperfect engines, that something is lost, creeps 0:11:14.880 --> 0:11:18.040 out of your cycle. This is an imperfect engine. Eventually 0:11:18.080 --> 0:11:20.520 it'll wind down, you'll turn a heat difference into work, 0:11:20.520 --> 0:11:22.440 and then you'll turn that work into a heat difference. 0:11:22.600 --> 0:11:24.600 But you get a little bit less, sort of like 0:11:24.600 --> 0:11:26.840 the way if you drop a ball. In principle, the 0:11:26.840 --> 0:11:29.840 potential energy the ball turns into kinetic energy and then 0:11:29.880 --> 0:11:32.480 it bounces back up and it regains all of that 0:11:32.480 --> 0:11:35.319 potential energy. But in practice there's a little bit of 0:11:35.400 --> 0:11:37.520 friction and there's losses in the system, and the ball 0:11:37.600 --> 0:11:41.479 doesn't bounce forever, right, in the same way. He understood 0:11:41.559 --> 0:11:44.240 that this happened, but he didn't describe it mathematically. It 0:11:44.280 --> 0:11:47.000 wasn't for a few more decades that people sort of 0:11:47.200 --> 0:11:50.920 described this with equations and sort of more mathematical concepts. 0:11:51.120 --> 0:11:53.480 Okay, but even today, we don't have a perfect engine, right, 0:11:53.559 --> 0:11:54.960 all of our engines are imperfect. 0:11:55.240 --> 0:11:58.360 All of our engines are imperfect. Exactly. And it was 0:11:58.440 --> 0:12:01.040 Claussius who sounds like he's it would be an ancient 0:12:01.040 --> 0:12:05.760 Greek guy he does, I know, yeah, exactly. I imagine 0:12:05.840 --> 0:12:07.560 him in a robe, even though he probably just wore 0:12:07.559 --> 0:12:10.120 a suit and had a top hat. But Classius defined 0:12:10.120 --> 0:12:13.120 it mathematically, and he thought of it as the stuff 0:12:13.160 --> 0:12:17.040 that's flowing, like entropy is leaving the system, it's moving 0:12:17.120 --> 0:12:20.160 through It's like a physical thing. And he connected it 0:12:20.160 --> 0:12:23.800 to temperature. And so his contribution was essentially invent this 0:12:23.960 --> 0:12:28.280 concept of entropy to help us understand why some engines 0:12:28.320 --> 0:12:30.800 are imperfect. And he thought of it as a thing 0:12:30.840 --> 0:12:33.320 which flows to the system, like a real physical thing, 0:12:33.440 --> 0:12:36.400 not just like hey, here's a number, we're calculating it. 0:12:36.480 --> 0:12:39.320 We define it like you could invent anything, right, you 0:12:39.360 --> 0:12:42.160 could invent the jigiblions and define it as like the 0:12:42.240 --> 0:12:44.640 number of apples in the universe minus the number of 0:12:44.640 --> 0:12:48.160 ice cream cones. And that doesn't necessarily have to mean anything, right, 0:12:48.600 --> 0:12:50.920 But sometimes you invent a number and it means something 0:12:50.920 --> 0:12:53.480 in the universe. It like describes someone which actually exists 0:12:53.559 --> 0:12:57.240 or is important. And so he connected entropy not just 0:12:57.400 --> 0:13:01.480 to heat, but also to temperature. Right. Temperature also something 0:13:01.480 --> 0:13:03.640 people were trying to understand. And so we're going to 0:13:03.679 --> 0:13:05.800 get into the mathematics of what that all means and 0:13:05.840 --> 0:13:08.560 how it works a little later on. But Colossius's other 0:13:08.600 --> 0:13:12.760 big contribution was the word. He created the word entropy. 0:13:13.240 --> 0:13:16.120 Before this, we had heat and we had temperature. But 0:13:16.200 --> 0:13:20.120 Colossius created the word entropy to think about energy flow. 0:13:21.040 --> 0:13:24.719 And so at this point he's thinking about the movements 0:13:25.320 --> 0:13:28.120 of heat or the movement of energy. But like so 0:13:28.160 --> 0:13:29.800 when I think of entropy, I usually think of like 0:13:29.840 --> 0:13:32.200 stuff getting lost. Was the idea of stuff getting lost 0:13:32.280 --> 0:13:34.280 or getting disordered part of this idea or is he 0:13:34.400 --> 0:13:37.840 just tracking the flow of things not disordered? 0:13:37.840 --> 0:13:40.520 Disorder comes later with Boltzmann. We'll get to there in 0:13:40.520 --> 0:13:42.960 a minute. But he's thinking about the energy flow and 0:13:43.000 --> 0:13:45.840 where does it go, and he's using that to understand 0:13:45.880 --> 0:13:49.760 why engines will wind down, right for sure, because entropy 0:13:49.800 --> 0:13:52.840 is one of the reasons energy doesn't flow completely perfectly. 0:13:53.320 --> 0:13:55.520 But I also love the story of how he came 0:13:55.640 --> 0:13:58.200 up with the word. So entropy is like a word 0:13:58.200 --> 0:14:00.600 he invented. He took the letters E N from energy 0:14:00.640 --> 0:14:03.400 because it's related to energy, and then he took the 0:14:03.400 --> 0:14:06.679 word trophy from the Greek word for change. So he's like, oh, 0:14:06.720 --> 0:14:10.439 this is cool entropy. And you know, he was cognizant 0:14:10.480 --> 0:14:12.360 of the fact that this is something he was inventing, 0:14:12.559 --> 0:14:14.800 and it was kind of a recent idea. So that's 0:14:14.840 --> 0:14:16.920 why he reached all the way back to Greek, because 0:14:16.960 --> 0:14:19.800 he wanted it to connect it with like ancient languages 0:14:19.840 --> 0:14:23.360 and ancient thoughts, and he said, quote, I prefer going 0:14:23.400 --> 0:14:26.880 to the ancient languages for the names of important scientific quantities, 0:14:27.240 --> 0:14:29.400 so that they may mean the same thing in all 0:14:29.480 --> 0:14:32.200 living tongues. I think he was hoping that, like, if 0:14:32.200 --> 0:14:35.280 he uses a Greek root, then even like Romanians and 0:14:35.280 --> 0:14:38.920 Bulgarians and English speakers and everybody is going to have 0:14:39.040 --> 0:14:41.840 some understanding intuitively of what this concept means. 0:14:42.000 --> 0:14:49.880 Now I am imagining him saying that in a toga. 0:14:46.960 --> 0:14:48.560 He's carving it into marble. 0:14:48.320 --> 0:14:51.680 Right, and has history judged this to have been a 0:14:51.720 --> 0:14:52.320 good decision. 0:14:52.600 --> 0:14:54.680 I don't know. I mean, listen to the listeners, Like, 0:14:54.840 --> 0:14:57.240 entropy is very confusing. I don't think anybody has the 0:14:57.240 --> 0:15:00.840 same idea of what entropy is. And there's famous physicists 0:15:00.880 --> 0:15:03.560 a few decades ago, Leon Cooper, who won the Nobel 0:15:03.640 --> 0:15:06.560 Prize for superconductivity. So like a dude knows his stuff 0:15:06.640 --> 0:15:09.680 and he says the COLOSSI has quote succeeded in coining 0:15:09.680 --> 0:15:17.680 a word that means the same thing to everybody. Nothing. 0:15:19.600 --> 0:15:21.880 I don't know. If I invent something so pervasive that 0:15:21.920 --> 0:15:23.960 people are griping about it, then like, hey, you know 0:15:24.040 --> 0:15:27.640 I've done something. All publicity is good publicity, right, We'll. 0:15:27.400 --> 0:15:29.320 Never be sure about that, but okay. 0:15:30.360 --> 0:15:32.000 And so at this point we have sort of these 0:15:32.080 --> 0:15:35.840 macroscopic handles on it. We're describing temperature and energy and 0:15:36.040 --> 0:15:39.760 entropy as things we can measure about the stuff we experience, right, 0:15:39.800 --> 0:15:42.720 A macroscopic that means like stuff in our world the 0:15:42.800 --> 0:15:45.400 human scale, you know, like you can take a thermometer 0:15:45.480 --> 0:15:47.080 and you can put it in your water. You can 0:15:47.160 --> 0:15:50.160 measure the temperatures, the number you can measure about like 0:15:50.600 --> 0:15:54.000 large amounts of physical things. But people again wanted to 0:15:54.080 --> 0:15:58.160 understand these things microscopically, like what happens down below? If 0:15:58.160 --> 0:16:00.400 you're understanding the particles, what is this all mean? And 0:16:00.880 --> 0:16:02.240 on the show we do that a lot, and people 0:16:02.280 --> 0:16:04.160 are often writing in to ask me, like, well, what's 0:16:04.200 --> 0:16:07.880 really happening at the particle level during hawking radiation or 0:16:07.920 --> 0:16:10.560 when light bounces off a mirror or something like, what's 0:16:10.600 --> 0:16:14.600 really going on? As if like the reductionist explanation reveals 0:16:14.600 --> 0:16:17.680 something truer, And you know, we'll talk about that in 0:16:17.680 --> 0:16:19.400 a minute, but I want people to understand that there 0:16:19.400 --> 0:16:22.240 are many layers of the universe of reality. None of 0:16:22.280 --> 0:16:24.560 them are more true than the other. We have this 0:16:24.680 --> 0:16:27.360 sense that like, as you go deeper, maybe you're approaching 0:16:27.440 --> 0:16:31.560 some fundamental layer of explanation, but every layer is useful. 0:16:31.680 --> 0:16:34.160 You know, the macroscopic view, the human level view of 0:16:34.160 --> 0:16:36.720 the universe is just as valid and just as useful, 0:16:36.840 --> 0:16:40.200 even if there is another layer underneath. Because the amazing 0:16:40.200 --> 0:16:42.120 thing is that you can write equations that work to 0:16:42.160 --> 0:16:46.320 describe the macroscopic without understanding the microscopic. The universe gives 0:16:46.400 --> 0:16:49.480 us that that access to many different layers of reality. 0:16:49.840 --> 0:16:52.320 So if every layer is useful, what I'm hearing you 0:16:52.320 --> 0:16:55.480 say is that it's okay that I skip chemistry. I 0:16:55.520 --> 0:16:58.600 can focus on the other useful layers. We tell me 0:16:58.680 --> 0:16:59.280 just as much. 0:16:59.400 --> 0:17:01.520 I'm saying, and unfortunately you can quote me on this. 0:17:01.640 --> 0:17:04.919 Chemistry has its uses. There are places where there are 0:17:04.920 --> 0:17:08.360 problems you can't solve using biology or we're using physics. 0:17:08.440 --> 0:17:11.040 You need that intermediate step where you're like, you're thinking 0:17:11.040 --> 0:17:14.400 about the stoichiometry and whatever. So you're like, yes, chemist's 0:17:14.400 --> 0:17:17.320 out there. I appreciate you. It's not that chemistry is terrible, 0:17:17.359 --> 0:17:18.560 it's just that I can't do it. 0:17:18.840 --> 0:17:22.520 Same same Yep, No, I appreciate you too, all right. 0:17:22.680 --> 0:17:25.959 So then late eighteen hundreds we have Boltzmann. He's one 0:17:26.000 --> 0:17:29.280 of the guys that founded statistical mechanics and thinking about 0:17:29.320 --> 0:17:31.760 things in terms of the particles. You really want to understand, 0:17:31.760 --> 0:17:35.040 like what is temperature in terms of the particles, Like 0:17:35.040 --> 0:17:37.520 if I have something hot and something cold, what's going 0:17:37.600 --> 0:17:42.920 on microscopically? And he made this huge contribution connecting temperature 0:17:43.000 --> 0:17:47.760 to microscopic motion and specifically defining entropy in terms of 0:17:47.800 --> 0:17:51.520 what's going on microscopically. This is a huge leap forward 0:17:51.560 --> 0:17:54.439 and really one of the only places in physics or 0:17:54.440 --> 0:17:57.800 maybe even in science where we have a mathematical bridge 0:17:57.840 --> 0:18:01.000 between two different layers of reality, where you can take 0:18:01.080 --> 0:18:04.640 the microscopic understanding of like particles whizzing around and use 0:18:04.680 --> 0:18:08.639 it to derive the macroscopic rules right different levels of reality. 0:18:08.720 --> 0:18:10.879 Is like when you have different kinds of laws, Like 0:18:11.119 --> 0:18:14.280 particles have different behavior than liquid flowing, but we know 0:18:14.359 --> 0:18:16.760 liquids are made of particles, and so liquids are this 0:18:16.840 --> 0:18:19.760 thing that emerge from particles, and usually we don't know 0:18:19.760 --> 0:18:21.840 how to derive it. We can like find the laws 0:18:21.840 --> 0:18:24.359 for liquids and find the laws for particles, but we 0:18:24.400 --> 0:18:26.240 don't know how to connect them, right, Like you can't 0:18:26.240 --> 0:18:30.080 derive fluid mechanics from the standard model. But here he 0:18:30.200 --> 0:18:32.719 developed an understanding of what's going on for particles and 0:18:32.840 --> 0:18:35.760 he built the mathematical bridge, like you can derive the 0:18:35.840 --> 0:18:40.159 ideal gas law from Boltzmann's description of what's happening with 0:18:40.200 --> 0:18:43.080 these particles. It's amazing. It's like the only place I've 0:18:43.119 --> 0:18:46.119 ever seen this kind of connection where like, not only 0:18:46.119 --> 0:18:49.200 do you have a reductionist ability to see the lower level. 0:18:49.680 --> 0:18:52.919 But also there's like a mathematical bridge that shows you 0:18:53.080 --> 0:18:54.920 why it works. It's kind of incredible. 0:18:54.960 --> 0:18:56.000 Why is that so rare? 0:18:56.480 --> 0:18:59.160 Because the universe is complicated, you know, like to go 0:18:59.240 --> 0:19:02.040 from micros gopic to macroscopic, you have to describe a 0:19:02.040 --> 0:19:06.560 lot of stuff, and usually they're two hurdles chaos and approximations. 0:19:07.160 --> 0:19:10.879 Chaos because like, sometimes the tiny little details matter, you know, 0:19:10.960 --> 0:19:13.560 like butterfly flaps its wings in China, hurricane goes a 0:19:13.600 --> 0:19:16.800 different direction, like, so you can't ignore those little details, 0:19:16.960 --> 0:19:18.560 which means you have to keep track of lots and 0:19:18.560 --> 0:19:21.160 lots and lots of little details, like remember how many 0:19:21.200 --> 0:19:24.520 atoms there are in a drop of water, right, like 0:19:24.880 --> 0:19:27.879 Avagajo's number is a big, big number. Calculating all those 0:19:27.960 --> 0:19:31.880 details is essentially impossible, so you end up making approximations. 0:19:32.000 --> 0:19:36.000 And sometimes those approximations work, like Boltzmann's big contribution was 0:19:36.040 --> 0:19:39.960 finding ways to calculate these averages that work mostly, but 0:19:40.040 --> 0:19:42.119 sometimes they don't, and maybe we just don't have the 0:19:42.160 --> 0:19:44.680 right kind of math. So in principles should be possible, 0:19:45.160 --> 0:19:47.520 but the approximations we make along the way and the 0:19:47.600 --> 0:19:50.720 sensitivity to the little details make it really, really hard. 0:19:51.160 --> 0:19:52.480 That's why we need chemistry. 0:19:53.520 --> 0:19:56.679 All right, Well, on that note, let's take a break 0:19:56.800 --> 0:19:59.000