The Second Law of Thermodynamics

This BBC podcast is supported by ads outside the UK. [MUSIC] This is a poison-dart frog. For decades, so David Attenborough has shaped how we feel about the natural world. But for a long time, there was one topic he never talked about. I didn't believe that we could change the climate by human beings. Amirano Jochi? I'm Kai Wright. And on the next episode of Big Lives, as David Attenborough prepares to celebrate his 100th birthday, we explore how he took on the mission of his life. Listen to Big Lives wherever you get your podcasts. [MUSIC] Thanks for downloading the Anartime podcast. For more details about Anartime and for our terms of use, please go to bbc.co.uk/radio4. I hope you enjoy the program. Hello, the second law of thermodynamics can be simply stated thus. Energy spontaneously tends to flow from being concentrated in one place to becoming diffused and spread out. It was first formulated to explain how a steam engine worked. It can explain why a cup of tea goes cold if you don't drink it. And how a panor water can be heated to boil an egg. But its application has been found to be rather grander than this. The second law is now used to explain the big bang, the expansion of the cosmos, and even suggests our inexorable passage through time towards the heat death of the universe. It's been called the most fundamental law in all of science. And C.P. Snow and his two cultures wrote, "Not knowing the second law of thermodynamics is like never having read a work of Shakespeare." So what is the second law? What are its implications for time and energy in the universe? And does it appear to be refuted by the existence of life and the theory of evolution? With me to discuss the second law of thermodynamics is John Grieben, visiting fellow in astronomy at the University of Sussex and author of Deep Simplicity. Peter Atkins, professor of chemistry at Oxford University and author of Galileo's finger, and Monica Grady had a meteorite at the Natural History Museum. John Grieben, before we are going to detail of the second law, can you give us an indication of how a law which began concerning steam locomotives came to have such a broad application? Can you give us an overview? But it's because, as you said, it deals with heat. It deals with the flow of heat from one place to another. That's one manifestation of the second law. And of course, that was hugely important in the 19th century as Britain, in particular, industrialised and the rest of the world followed suit. If you could understand how heat worked, you could build more efficient steam engines, putting it very simply. And so your industry would be more efficient. But it goes hand in hand with developing technology. As you learn to develop better technology and better steam engines, then you learn more about the second law as well. So these things always in silence, sort of go hand in hand in a ratcheting process. And it goes back even a bit further than that, to earlier in the 19th century. There was a guy called Count Rumpford, who started lifers as Benjamin Thompson. And he was involved in boring cannon to make cannon for warfare. And he realised that the process of boring out the cannon generated heat in an inexhaustible fashion, which is the important thing. Before then, people had had the idea that heat was a kind of a fluid called caloric, which was existed in something. And if you heated it by friction, you'd rub it all out, and it'd all be used up. And he discovered that no matter how long you kept grinding away at the lumps of iron to make cannon, you kept producing heat. So there was this realisation that heat was a form of energy. It became understood as a form of energy. And energy, of course, is what drives the whole universe and keeps us going. So it's absolutely fundamental. Can you tell us just because the listeners will be clamoring to hear this, I'm sorry. What's the first law, I'm going to tell you? Right, well, the first law is very simple. It's a kind of sort of throat clearing, which says that the total amount of energy in the universe always stays the same. And it's been paraphrased, it's saying you can't get something for nothing. And the second law, in a similar vein, it's been paraphrased, it's saying things wear out. And so you're always losing useful energy. And what matters is that although the total amount of energy in the universe stays the same, you can only do work as in a steam engine by moving energy from a hot place to a cold place. And as you do so, some heat gets lost in the process. That's the second law at work. And eventually, as this goes on and on and on, the whole universe will end up at the same temperature. And if everything's the same temperature, you can't do anything useful. You can't run a steam engine in which both bits of the steam engine are at the same temperature. And so this is the idea that things will eventually wear out entirely. And that ties in with what you're talking about, the arrow of time. There's a past when things are lively and interesting, and heat flows are one place to another, and the future where everything's cold and dark and worn out. Throughout this first part of the programme, we're going to use the steam engine as a metaphor for big bang for all sorts of changes. You'll come on to Peter. Again, can you introduce us? Can we go further into the steam engine? And tell us how the theory grew out of the practice. Because that's one of the fascinating things. These men are working away, making this thing to go along railway lines. And the theory develops alongside or around it. Can you tell us how I say the French physicist, Sadi Cano, what he did about it? I think there are really four people who constructed the second law. One is Sadi Cano. Another was William Thompson, Lord Kelvin later. And then there was Rudolf Clausius. And finally, there was Ludwig Bultzmann. And each made a very special contribution to understanding. Cano looked at the steam engine and tried to identify what was the limits of its efficiency. Everyone thought at the time that England was producing its munitions. It was pumping its wells and so on, pumping its minds with steam. And the French were terrified. So there was a huge interest in France on making their machines more efficient. And Cano looked at the structure of a steam engine and tried to think what it was that determined its ultimate efficiency. Most people at the time thought that it might be changing the pressure. It might be changing the working substance from, say, steam to air and so on. But Cano came up with what turned out to be an absurd idea in the views of his contemporaries, that it was only the temperature. That, as John just mentioned, the steam engine really consists of three bits. There's the hot reservoir. There's the cold sink where you throw away some heat. And there's the guppins in between, really. The piston which converts heat into work. And Cano, by thinking about the machine, decided that it was only the temperature of the hot source and the temperature of the cold sink that determined its ultimate efficiency. What were the, briefly, the chief modifications at the other, extensions at the other three that you mentioned gave to it? Well, Cano's views were seen to be so absurd that they were ignored, which I suppose ringlet was a good thing. But then his book so survived in print and Kelvin came across it and started to think about it in a more detail. And he came up with a view that really the most important part of a steam engine was not the hopper. It was not the piston. It was the cold bit. And he said effectively, and this is yet another statement of the second law of thermodynamics that steam engines don't work unless you've got the cold sink. The next person to come along was Rudolf Tazius. And he said something that we all know anyway, that heat doesn't flow from a cold object to a hot object. And finally, can briefly, you've got the other one to go at the bottom. At another man, his ideas were dismissed as completely absurd. He was, what's my suppose, was short-sighted physically, but he saw more into the nature of the world than anyone else. And he identified the molecular basis of the second law, that why it is that what we have been saying is true in terms of the behavior of individual atoms and molecules. And that's which will come onto, I think, his a major revelation about why the world works in the way that it does. Monica Grady, Kelvin, and Lord Kelvin understood that you had to let some heat escape if other heat was to use to power the turbines. In other words, some heat had to be jettisoned. Now, where does this fit in? I mean, we've got two very powerful introductions from John and from Peter. Where do we go next, then, to sort of build up the theory alongside the steam engine? Well, we have to look at where the heat's going to and what this system is, John referred to equilibrium, and you tend to get equilibrium in a closed system. And of course, in a closed system, you won't get this work happening. You can tell the list of what you mean by a closed system. Oh, a system where nothing can escape. Like a sealed box. Like a sealed box. A sealed box is a closed system. You're not putting heat in, you're not putting, allowing any heat to escape. You have a closed system. Now, in a system like that, you're not going to be able to do any work, because you're not going to get a change, you're not going to allow i hwn am i debatedi. Mae Ев ei ffled British King oedd Full Time' sfor�, a Dymeidaeth sy'n 다 [on] mty sy'n ringa�d yna, einashing o ffr advice να 'Pfldis gerdys Bethonych [ gör er enw y trio pinch] neu Fredmynseli na beth i enw baperacht y cyliwan y gallu g decree. Cliforaethref hint a pauteru ac mae hyn nhw ghorau dwy thi full memory amn de Rovan Y alkohodaethau'n bandau fydd yn gydraethio dipes o hynnybrian yr holl am gyflwn mae Needlesio. Mae'n gwaithio'r cymryd i'n gwaithio'r cymryd i'n gwaithio'r cymryd i'n gwaithio'r cymryd amn y gallu'r cymryd i'n gwaithio'r cymryd i'n gwaithio'r cymryd a gwaithio'r cymryd i'n gwaithio'r cymryd i'n gwaithio'r cymryd noi Eat, eich hyd yn y biasive barchwydd imiAHes. Ysgdwch i dalரó någonting ac rhag allaniedenietholi enterujin. Iolid fawr, Sicherwch, yn stemowe diesaud o' gyfer o'r ei Rydyn Beenis roedd hodd yn vegetafiolain ag esui… …ohu feth Sylwyddo gyfer ddol it yn asog neu roedd yn y smi hynny. Celtic ris ho, yn manach —Тyrt Gym雜 Doed mor fel Cymru. Mae poig брethaf imbarnyt am dyng meidir yn uniryscies? Mae banen beth i cyn OVER, un eraill fy nhw cyith popwps. Myn o seei healed heri'i atyn cotsi peral ei ddwyci ti wrth fyddnya fel sym nursingoeddol fel eu rodion. llen, Idd early, oedag i'r Fiordiad gwneud o dit lefgan fel sut a totalau oанheidlu'r Ö uny fließf, siethau roedd yn themi signalydd yn hynny'r wal wedi, Mynd to fewn cyflwedd o pan, qui変wysig… Kin falleth o boswirnau eisiau ty wedi ei afarwysig aля. Tyn ar ei faddir sylfa i ddiallol fel hosteddeol… …asyt, mae'n eu gallu ac feb newis bod nhw i qualifications, gwy wal clywl fyrde chial neu ei siad digidael o iddym yn cofnion? ั gwlin ynew blau ceithau, chysyllti ei funggen Manya电au a bryrch rel going missing maenethig i Flasht Posiy go CJM consistency â-udeh mae lawf wedi, yn ddim ei'r cymryd cylまた gy upredar a mae'r cy步oso a wasôn enrhyw clyflyaf pas Mae cyhru'n g 캐�g速 stroke, fwy maeneth fy nÜNDNIS son a'r cyhru'n g 캐�g速 o'r cyhru'n g 캐�g速? 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Cyfyd yn ei fy minna fel cyhoŵn yn well an afternoon ac yna yw i asymmyn yn istas ddan beth swy wedi effynirant yr llawer eich sy'n ziannaethi Dogs 6. and the fuel is burning and the energy released in that way spreads and the carbon dioxide and water that is produced when the fuel burns also disperses. The fuel is a way of tapping into that dispersal and you use it to drive pistons and so on and then you can connect those pistons through gears to bricks which you build into a cathedral and so on. So you can use this dispersal constructively and that's the crucial idea. And you can transform the same idea to for example when you eat in the morning the food that you ingest undergoes metabolism and so on it breaks down it releases energy. I think it is fuel once again and instead of having a mechanical train of pistons and gears like in a car what you've got is a biochemical train of gears and so on which can be used to not in this case to to one brick upon another to build a cathedral but to put one amino acid next to another to build a protein. So in other words as you eat and disperse energy so you grow and the processes of life continue and you can be even more fanciful if you like that if you think of the random electrical currents in your brain becoming organized by the same kind of process in order to you eat and through the biochemical process is that occur and drive the neuro physical processes in your brain. You think and so an act of creation like writing a piece of poetry giving this talk any an act of gallantry and so on are all ultimately driven by the dispersal of energy and that is why it is so far reaching both both those examples of course that ultimately to paint on energy from the sun the fuel we use in the car has come from stored up sunlight in plant remains and the food is ultimately from stored up sunlight in plants and what's happening is that we've got a negative entropy happening locally because the sun is is making positive entropy in a much larger scale. I want Monica to unravel that a bit a negative entropy happening locally. Can you just describe how the sun works in our system and prevents our own planet from being a closed system and therefore just stay with our planet and the sun at the moment. And therefore has the effects it has on the entropy here could you just take that on a minute. Yes certainly I mean if you look at life and this building up of life you might think well that is something that's becoming more complex but when we look at a larger system like the system which incorporates the sun then we see what's actually happening is the sun is this enormous ball of hydrogen and the hydrogen is fusing together to become atoms of helium and as it does that it gives out a positive energy. That gives out heat and light and that heat and light bathes the earth it powers our atmosphere our climate our weather it powers the carbon cycle the water cycle so it powers the whole of life on earth. So let's move it further out now John Grimian and go to the big bang were presumably if if if disorder is is coming from order then we can look for a point where there was only order and then we never to be go back to the big bang is that right. No that's wrong it's a big puzzle it was a big puzzle until quite recently the big bang the birth of the universe seems to have been a very disordered state and we now know this from looking at the famous background radiation. The microwave background radiation which gives us a picture of what the universe was like when it was only a few hundred thousand years old a few hundred thousand years after the big bang at about 13 billion years ago the universe was very smooth and well distributed and it was a fairly uniform sea of hot gas. Now what's happened to the heat is that that heat has degraded and it's cooled down to become the very cool background radiation but what's happened to the matter is that it's been turned into stars and galaxies by gravity and you have actually made a much more structured system out of a disorder system thanks to gravity and gravity has a remarkable property which wasn't properly appreciated until relatively recently is that it runs this whole process backwards. Can you introduce can you develop the idea of Monica Grady of the heat death the universe following an inevitable cause towards what will be a heat death of the universe because of the working of the second law of thermodynamics. Yes this follows on from what Peter was saying about this constant expansion and the constant flow of energy as coming back to our star it converts hydrogen to helium gives out heat that the hydrogen will eventually run out the helium will be converted to carbon giving out more heat. This is happening in all sorts of stars some stars explode become supernovae again giving out huge tremendous amounts of energy. unn ni assessing gallu'r uw gynhakais use'u cancerin, terrible ni profanaaf roeddol— ym rhan egiol o tent ariru eu gallu fwegau rhoi'n figgoud, eraill ni bod tiesrwynt牛 yn y sinn yn gyda'r unegafdegau achno ar ei hyffirgiadol proceeded. Eur wedi recycled weaker sryfftis cael ei lefo wedi rydig僞au ei serf direct嗎ru. Mae'r gynny, ac yn ymwch yn y gallu'r gynny, ymwch yn ysgwyrddio, yn y pethau cywbethau, yn ysgwyrddio'r gynny, yn ysgwyrddio, wedi rydig yn ddyn yn ysgwyrddio, a yw'r gynny, ac yn yr unigafdeg yn cyfru. Ymwych yn cylwfru yn yr cylwfru, ac yn yr hynny, yn yr hynny, yn yr hynny, yn yr hynny, yn yr ysgwyrddio, un i welν gifolain ar yr strengthened oedd drawers o rythmi cymde warmau earlwl. Roedd nhw i agio g輕is trw amg oedd hynny ddim, ceid wedi eu crynaeth i slwydd o cyndfeodyd ac mae'n rydli de sydd y ffeid yn roster a hwn yn se Tomato factors a gyda i fo열 o chi Potw i las Chraddiol Kenneth Lleweydd mig. yn seos i te auchó quefodos. Cymru ple うfial و ac amn aggol farbylododton a gweithillerd a dowdi dovoddi sailor. Cl引 eraill wntan hefo, creudin norfr fibryигр a physiófer unt breathu. ac oedog sine An lefn captair ryd ddys, collcektor ar yn siop yng Nghyrhow y gallu unashtaf. Mae'n gydol oedd yn cwthwyr i'r gweithill, ac oedd yn ffwrddol oedd yn ymwyr, i'r gwaith, ac yn cael ymwyllfaith. A mae'n gweithill yn yna, yna amser, ac yna yn yna oedd yn yna oedd yn yna. Yn gweithill, ac yna yn yna oedd yn yna, yna oedd yn yna, yna fŵr yna. Yna gweithill, ac yna oedd yn yna i'n yna oedd yn yna, yna gweithill, ac yna oedd yn yna. usат hyn cat yn y wneilu rosyn a olorau y cy Schönag�� y ddell hynny ym yn unrhygiwch. Mae'n gwybod o'r hynny. I'm your baby. I'm your baby. I'm Kai Wright. On the next episode of Big Lives as David Attenborough prepares to celebrate his 100th birthday we explore how he took on the mission of his life. We'll be back in a few minutes. See you next week.