1 00:00:01,920 --> 00:00:06,600 Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey 2 00:00:06,680 --> 00:00:10,280 Speaker 1: brain Stuff, Lauren Bogle bomb here. You can't easily put 3 00:00:10,320 --> 00:00:14,280 Speaker 1: the toothpaste back into the tube. You can't expect molecules 4 00:00:14,280 --> 00:00:17,639 Speaker 1: of steam to spontaneously migrate back together to form a 5 00:00:17,680 --> 00:00:20,840 Speaker 1: panful of water. If you release a bunch of corky 6 00:00:20,920 --> 00:00:23,880 Speaker 1: puppies into a field, it's very unlikely that you're going 7 00:00:23,920 --> 00:00:25,400 Speaker 1: to be able to get all of them back together 8 00:00:25,440 --> 00:00:29,479 Speaker 1: into a crate without doing a ton of adorable fluffy work. 9 00:00:30,760 --> 00:00:34,320 Speaker 1: These are the problems associated with the second law of thermodynamics, 10 00:00:34,400 --> 00:00:38,720 Speaker 1: also known as the law of entropy. Thermodynamics is important 11 00:00:38,760 --> 00:00:43,120 Speaker 1: to various scientific disciplines, from engineering to natural sciences, to chemistry, 12 00:00:43,159 --> 00:00:47,400 Speaker 1: to physics, and even economics. A thermodynamic system is a 13 00:00:47,440 --> 00:00:50,680 Speaker 1: confined space which doesn't let energy in or out of it. 14 00:00:51,920 --> 00:00:54,360 Speaker 1: The first law of thermodynamics has to do with the 15 00:00:54,440 --> 00:00:57,480 Speaker 1: conservation of energy. You know that the energy in a 16 00:00:57,520 --> 00:01:01,360 Speaker 1: closed system remains constant. That is, energy can be neither 17 00:01:01,480 --> 00:01:05,840 Speaker 1: created nor destroyed, that is, unless the system is tampered 18 00:01:05,880 --> 00:01:10,480 Speaker 1: with from the outside. However, the energy in a system 19 00:01:10,520 --> 00:01:14,720 Speaker 1: constantly changes. Forms of fire can turn chemical energy from 20 00:01:14,720 --> 00:01:19,520 Speaker 1: a plant into thermal and electromagnetic energy. Battery turns chemical 21 00:01:19,600 --> 00:01:24,360 Speaker 1: energy into electrical energy. The world turns and energy becomes 22 00:01:24,600 --> 00:01:28,640 Speaker 1: less organized. This is entropy, and it's one of the 23 00:01:28,720 --> 00:01:33,800 Speaker 1: laws that demonstrates how our universe works. So entropy is 24 00:01:33,840 --> 00:01:37,480 Speaker 1: a measure of the disorder in a closed system. According 25 00:01:37,480 --> 00:01:40,760 Speaker 1: to the second law of thermodynamics, entropy in a system 26 00:01:40,880 --> 00:01:44,680 Speaker 1: almost always increases over time. You can do work to 27 00:01:44,800 --> 00:01:47,560 Speaker 1: create order in a system, but even the work that's 28 00:01:47,560 --> 00:01:52,720 Speaker 1: put into reordering increases disorder as a byproduct, usually in 29 00:01:52,760 --> 00:01:56,400 Speaker 1: the form of heat. Because the measure of entropy is 30 00:01:56,440 --> 00:02:00,240 Speaker 1: based on probabilities, it is of course possible for the 31 00:02:00,360 --> 00:02:03,640 Speaker 1: entropy to decrease in the system on occasion, but it's 32 00:02:03,640 --> 00:02:08,239 Speaker 1: statistically very unlikely. It's harder than you think to find 33 00:02:08,280 --> 00:02:10,919 Speaker 1: a system that doesn't let any energy in or out. 34 00:02:11,520 --> 00:02:13,680 Speaker 1: Our universe is as good of an example as we have, 35 00:02:14,440 --> 00:02:17,040 Speaker 1: but after accounting for the fact that it's usually not 36 00:02:17,080 --> 00:02:20,919 Speaker 1: going to be mathematically perfect, entropy does help describe how 37 00:02:20,960 --> 00:02:23,920 Speaker 1: disorder happens in a system as large as the galaxy 38 00:02:24,120 --> 00:02:28,640 Speaker 1: or small as a thermos full of coffee. However, entropy 39 00:02:28,760 --> 00:02:30,760 Speaker 1: doesn't have to do with the type of disorder you 40 00:02:30,800 --> 00:02:33,320 Speaker 1: think of when you lock a bunch of chimpanzees in 41 00:02:33,360 --> 00:02:36,000 Speaker 1: a kitchen, it has more to do with how many 42 00:02:36,120 --> 00:02:39,560 Speaker 1: possible permutations of mess can be made in that kitchen, 43 00:02:40,080 --> 00:02:43,680 Speaker 1: rather than how big of a mess is possible. Of course, 44 00:02:43,720 --> 00:02:46,959 Speaker 1: the entropy depends on a lot of factors, how many 45 00:02:47,040 --> 00:02:49,880 Speaker 1: chimpanzees there are, how much stuff is being stored in 46 00:02:49,919 --> 00:02:53,399 Speaker 1: the kitchen, and how big the kitchen is. So if 47 00:02:53,400 --> 00:02:56,600 Speaker 1: you were to look at two kitchens, one very large 48 00:02:56,639 --> 00:02:59,880 Speaker 1: and stocked to the gills but meticulously clean and organized, 49 00:03:00,240 --> 00:03:03,200 Speaker 1: and another that's smaller, with less stuff in it but 50 00:03:03,360 --> 00:03:07,239 Speaker 1: pretty baseline messy, it's tempting to say that the messier 51 00:03:07,320 --> 00:03:11,000 Speaker 1: room has more entropy, but that's not necessarily the case. 52 00:03:11,880 --> 00:03:15,080 Speaker 1: Entropy concerns itself more with how many different states are 53 00:03:15,120 --> 00:03:18,560 Speaker 1: possible than how disordered it is at the moment. A 54 00:03:18,600 --> 00:03:22,480 Speaker 1: system therefore, has more entropy if there are more molecules 55 00:03:22,480 --> 00:03:25,760 Speaker 1: and atoms in it, and if it's larger, and if 56 00:03:25,760 --> 00:03:31,040 Speaker 1: there are more chimpanzees. Entropy might be the truest scientific 57 00:03:31,080 --> 00:03:35,240 Speaker 1: concept that the fewest people actually understand. Honestly, me sort 58 00:03:35,280 --> 00:03:38,920 Speaker 1: of included. The concept of entropy can be very confusing, 59 00:03:39,240 --> 00:03:43,880 Speaker 1: partly because there are actually different types. The Hungarian mathematician 60 00:03:44,000 --> 00:03:47,960 Speaker 1: John von Neumann lamented the situation by saying, whoever uses 61 00:03:47,960 --> 00:03:50,960 Speaker 1: the term entropy in a discussion always wins, since no 62 00:03:51,000 --> 00:03:53,800 Speaker 1: one knows what entropy really is, so in a debate, 63 00:03:54,040 --> 00:03:58,120 Speaker 1: one always has the advantage. We spoke via email with 64 00:03:58,160 --> 00:04:02,320 Speaker 1: one Marko Popovich, a post auctoral researcher in bio thermodynamics 65 00:04:02,320 --> 00:04:04,920 Speaker 1: in the School of Life Sciences at the Technical University 66 00:04:04,960 --> 00:04:09,080 Speaker 1: of Munich. He said, it's a little hard to define entropy. 67 00:04:09,120 --> 00:04:13,280 Speaker 1: Perhaps it's best defined as a non negative thermodynamic property 68 00:04:13,480 --> 00:04:16,120 Speaker 1: which represents a part of energy of a system that 69 00:04:16,200 --> 00:04:20,800 Speaker 1: cannot be converted into useful work. Thus, any addition of 70 00:04:20,880 --> 00:04:23,320 Speaker 1: energy to a system implies that a part of the 71 00:04:23,400 --> 00:04:27,440 Speaker 1: energy will be transformed into entropy, increasing the disorder in 72 00:04:27,440 --> 00:04:31,839 Speaker 1: the system. Thus, entropy is a measure of disorder of 73 00:04:31,880 --> 00:04:36,720 Speaker 1: a system. But don't feel bad if you're still confused. 74 00:04:37,080 --> 00:04:40,400 Speaker 1: The definition can vary depending on which discipline is wielding 75 00:04:40,440 --> 00:04:44,159 Speaker 1: it at the moment. For example, in the mid nineteenth century, 76 00:04:44,240 --> 00:04:47,640 Speaker 1: a German physicist named Rudolph Classius, one of the founders 77 00:04:47,640 --> 00:04:50,719 Speaker 1: of the concept of thermodynamics, was working on a problem 78 00:04:50,800 --> 00:04:55,000 Speaker 1: concerning efficiency in steam engines, and he invented the concept 79 00:04:55,000 --> 00:04:58,599 Speaker 1: of entropy to help measure useless energy that cannot be 80 00:04:58,680 --> 00:05:03,279 Speaker 1: converted into eve full work. A couple decades later, Ludwig 81 00:05:03,360 --> 00:05:07,520 Speaker 1: Boltzman entropies other founder used the concept to explain the 82 00:05:07,520 --> 00:05:11,599 Speaker 1: behavior of immense numbers of atoms, like even though it's 83 00:05:11,600 --> 00:05:15,000 Speaker 1: impossible to describe the behavior of every single particle in 84 00:05:15,000 --> 00:05:18,040 Speaker 1: a glass of water, it's still possible to predict their 85 00:05:18,080 --> 00:05:22,960 Speaker 1: collective behavior when they're heated using a formula for entropy, 86 00:05:23,480 --> 00:05:27,640 Speaker 1: Popovich said. In the nineteen sixties, the American physicist T. S. 87 00:05:27,760 --> 00:05:32,280 Speaker 1: Jayne's interpreted entropy is information that we miss to specify 88 00:05:32,320 --> 00:05:35,960 Speaker 1: the motion of all particles in a system. For example, 89 00:05:36,360 --> 00:05:39,800 Speaker 1: one mole of gas consists of six times ten to 90 00:05:39,880 --> 00:05:43,400 Speaker 1: the power of twenty three particles. Thus, for us, it 91 00:05:43,480 --> 00:05:47,000 Speaker 1: is impossible to describe the motion of each particle, so 92 00:05:47,080 --> 00:05:50,159 Speaker 1: instead we do the next best thing by defining the 93 00:05:50,200 --> 00:05:52,760 Speaker 1: gas not through the motion of each particle, but through 94 00:05:52,760 --> 00:05:58,120 Speaker 1: the properties of all the particles combined temperature, pressure, total energy. 95 00:05:58,320 --> 00:06:01,479 Speaker 1: The information that we lose when we do this is 96 00:06:01,520 --> 00:06:07,280 Speaker 1: referred to as entropy, and the terrifying and or fascinating 97 00:06:07,320 --> 00:06:09,840 Speaker 1: concept of the heat death of the universe wouldn't be 98 00:06:09,880 --> 00:06:14,120 Speaker 1: possible without entropy, because our universe most likely started out 99 00:06:14,200 --> 00:06:17,520 Speaker 1: as a singularity, as an infinitely small ordered point of 100 00:06:17,600 --> 00:06:20,960 Speaker 1: energy that ballooned out and continues expanding all the time. 101 00:06:21,520 --> 00:06:25,000 Speaker 1: Entropy is constantly growing in our universe because there's more 102 00:06:25,080 --> 00:06:28,599 Speaker 1: space and therefore more potential states of disorder for the 103 00:06:28,640 --> 00:06:33,880 Speaker 1: atoms here to adopt. The scientists have hypothesized that long 104 00:06:33,920 --> 00:06:36,880 Speaker 1: after you and I are gone, the universe will eventually 105 00:06:36,880 --> 00:06:40,640 Speaker 1: reach some point of maximum disorder, at which point everything 106 00:06:40,680 --> 00:06:43,680 Speaker 1: will be the same temperature, with no pockets of order 107 00:06:43,880 --> 00:06:48,760 Speaker 1: like stars and chimpanzees to be found. And if that happens, 108 00:06:48,839 --> 00:06:56,080 Speaker 1: we'll have entropy to thank for it. Today's episode was 109 00:06:56,080 --> 00:06:58,760 Speaker 1: written by Josceline Shields and produced by Tyler Klang. For 110 00:06:58,800 --> 00:07:00,560 Speaker 1: more on this lots of other top x visit how 111 00:07:00,600 --> 00:07:03,120 Speaker 1: stuff works dot com. Brain Stuff is a production of 112 00:07:03,160 --> 00:07:05,480 Speaker 1: I Heart Radio. For more podcasts from my heart Radio, 113 00:07:05,600 --> 00:07:08,159 Speaker 1: visit the I heart Radio app, Apple Podcasts, or wherever 114 00:07:08,240 --> 00:07:09,520 Speaker 1: you listen to your favorite shows.