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Explores how humanity discovered the fundamental laws governing the universe, reveals how energy drives everything from engines to stars and is bound by the relentless increase of entropy....
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00:07How did humans acquire the power to transform the planet like this?
00:14Looking at the Earth at night reveals to us just how successful we've been
00:18in harnessing and manipulating energy and how important it is to our existence.
00:34Energy is vital to us all. We use it to build the structures that surround and protect us.
00:40We use it to power our transport and light our homes.
00:45And even more crucially, energy is essential for life itself.
00:48Without the energy we get from the food we eat, we die.
00:52But what exactly is energy? And what makes it so useful to us?
01:01In attempting to answer these questions, scientists would come up with a strange set of laws
01:07that would link together everything from engines to humans to stars.
01:13It turns out that energy so crucial to our daily lives also helps us make sense of the entire universe.
01:27This film is the intriguing story of how we discovered the rules that drive the universe.
01:40It's the story of how we realised that all forms of energy are destined to degrade and fall apart.
01:53To move from order to disorder.
02:01It's the story of how this amazing process has been harnessed by the universe
02:06to create everything that we see around us.
02:11Of course.
02:23The end.
02:31So…
02:31Oh, there everyone looks like the world.
02:32There we go.
02:32Oh, there we go.
02:32Oh, there you go.
02:36Oh, here we go to you.
02:37There we go to the world.
02:37Yeah, yeah, yeah.
02:39It makes sense of everything we can remember.
02:47Over the course of human history, we've come up with all sorts of different ways of extracting
02:53energy from our environment.
02:55Everything from picking fruit, to burning wood, to sailing boats, to water wheels.
03:02But around 300 years ago, something incredible happened.
03:06Humans developed machines that were capable of processing extraordinary amounts of energy
03:12to carry out previously unimaginable tasks.
03:16Now, this happened thanks to many people and for many different reasons,
03:19but I'd like to begin this story with one of the most intriguing characters in the history of science.
03:25One of the first to attempt to understand energy.
03:46Godfrey Leibniz was a diplomat, scientist, philosopher and genius.
03:51He was forever trying to understand the mechanisms that made the universe work.
03:58Leibniz, like several of his great contemporaries, was absolutely convinced that the world we see around us
04:04is a vast machine designed by a powerful and wise person.
04:10And if you could understand how machines worked, you could therefore understand how the universe
04:18and the principles that had been used to make the universe worked as well.
04:24And so there was an extremely close relationship for Leibniz between theology and philosophy on the one hand
04:33and engineering and mechanics on the other.
04:39It was this relationship between philosophy and engineering that in 1676 would lead him to investigate
04:46what at first sight seemed to be a very simple question.
04:57What happens when objects collide?
04:59This is what Leibniz and many of his contemporaries were grappling with.
05:04So when these two balls bump into each other,
05:07the movement of one gets transferred to the other.
05:12It's as though something's being passed between them.
05:14And this is what Leibniz called the living force.
05:19He thought of it as a stuff, as a real physical substance that gets exchanged during collisions.
05:34The world is a living machine.
05:35Leibniz argued that the world is a living machine.
05:40And that inside the machine, there is a quantity of living force put there by God at the creation
05:47that will stay the same forever.
05:49So the amount of living force in the world will be conserved.
05:53The puzzle was to define it.
06:01Leibniz would soon find a simple mathematical way to describe the living force.
06:07But he would also see something else.
06:12He realised that in gunpowder, fire and steam,
06:17his living force was being released in violent and powerful ways.
06:35If this could be harnessed, it could give humankind unimaginable power.
06:51Leibniz would soon become fascinated with ways of capturing the living force.
07:03A prolific letter writer, Leibniz struck up correspondence with a young French scientist called Denis Papin.
07:15As they corresponded, Leibniz and Papin realised the living force released in certain situations could indeed be harnessed.
07:26Heat could be converted into some form of useful action.
07:36But how far could this idea be taken?
07:40Papin was in no doubt.
07:42This is an extract from his letter to Leibniz.
07:48I can assure you that the more I go forward, the more I find reason to think highly of this
07:53invention,
07:54which in theory may augment the powers of man to infinity.
07:59But in practice, I believe I can say without exaggeration
08:02that one man by this means will be able to do as much as a hundred others can do without
08:08it.
08:11Now, you might expect me at this point to tell you that Leibniz and Papin changed the world forever.
08:18Well, they hadn't.
08:20Their ideas have been profound and far-reaching, yes, but they hadn't really moved things forward.
08:25For that you need something much more tangible.
08:29You need innovation, industry.
08:32You need countless skilled workers and craftsmen who are going to apply these ideas,
08:37to experiment with them in novel and new ways.
08:41Well, in the century that followed Leibniz and Papin,
08:44this would take place in the most dramatic way imaginable.
08:57150 years after Leibniz and Papin's discussions, the living force had been harnessed in spectacular ways.
09:06The machines they'd dreamed of had become a reality.
09:10Steam engines were now the cutting edge of 19th century technology.
09:23If you look at steps in civilization, then one great step was the steam engine,
09:30because it replaced muscle, animal muscle, including our muscle, by steam power.
09:36And the steam power was effectively limitless and hugely important to doing almost unimaginable things.
09:51But steam technology would do more than just transform human society.
09:56It would uncover the truth about what Leibniz had called the living force,
10:01and reveal new insights about the workings of our universe.
10:11This is Crossness in south-east London.
10:15It's an incredible industrial cathedral,
10:18and home to some of the most impressive Victorian steam engines ever built.
10:33Constructed in 1854, Crossness houses four huge engines that once required 5,000 tonnes of coal each year to drive
10:45their 47-tonne beams.
11:02Everything about this place seems to have been built to impress, from the lavish ironwork, the grand pillars like something
11:11out of a Greek or Roman temple.
11:13It's the sort of effort you'd think would have been lavished on a luxury ocean liner for the rich and
11:19famous.
11:20And yet this place was built to process sewage.
11:25Although only a few workers and engineers would have seen the insides of this place,
11:29steam had become such a vital part of British power and economic prosperity that it was afforded almost religious respect.
11:53But for all the great success and immense power the engines were bestowing on their creators,
11:59there was still a great deal of confusion and mystery surrounding exactly how and why they worked.
12:06In particular, questions like how efficient could they be made?
12:10Were there limits to their power?
12:13Ultimately, people wanted to know just what might it be possible to achieve with steam?
12:29The reason these questions persisted was simple.
12:33Almost no one had understood the fundamental nature of the steam engine.
12:38Very few were aware of the cosmic principle which underpinned it.
12:46These great lumbering machines that we think of as the early steam engines actually were the seed of understanding of
12:55everything that goes on in the universe.
13:02As unlikely as it sounds, steam engines held within them the secrets of the cosmos.
13:32This is the Chateau de Vincennes in Paris.
13:36Events here would motivate one man's journey,
13:39to uncover the cosmic truth about the steam engine and help to create a new science.
13:46The science of heat and motion.
13:50Thermodynamics.
14:02Thermodynamics.
14:05In March 1814, during the Napoleonic Wars, when Napoleon and his armies were fighting elsewhere,
14:12Paris itself came under sustained attack from the combined forces of Russia, Prussia and Austria.
14:18And citizens of the city were deployed around key locations to protect them.
14:24Now, this chateau was being defended by a group of inexperienced young students,
14:29who were forced to retreat under sustained artillery fire.
14:34One of them was a brilliant young scientist and soldier.
14:37His name was Nicola Leona Sadi Karno.
14:41And the humiliation he felt personally would drive him and motivate him to uncover a profound insight into how all
14:50engines work.
14:56Karno came from a highly respected military family.
15:00After the French defeat here and elsewhere around Europe,
15:03he became determined to reclaim French pride.
15:12What really bothered Karno was the technological superiority that France's enemies seem to possess.
15:20And Britain, in particular, had this huge advantage, both militarily and economically,
15:27because of its mastery of steam power.
15:30So Karno vowed to really try and understand how steam engines work and use that knowledge for the benefit of
15:39France.
15:41He says absolutely explicitly that if you could take away steam engines from Britain,
15:48then the British Empire would collapse.
15:51And he's writing in the wake of French military defeat.
15:55And he proposes to analyse, literally, the source of British power by analysing the way in which fire and heat
16:06engines work.
16:10Living on half pay with his brother Hippolyte in a small apartment in Paris,
16:15in 1824, Karno wrote the now legendary Reflections on the Motive Power of Fire.
16:23In just under 60 pages, he developed and abstracted the fundamental way in which all heat engines work.
16:31Karno saw that all heat engines comprised of a hot sauce in cooler surroundings.
16:38Now Karno believed that heat was some kind of substance that would flow like water from the hot to the
16:45cool.
16:46And just like water falling from a height, the flow of heat could be tapped to do useful work.
16:59Karno's crucial insight was to show that to make any heat engine more efficient, all you had to do was
17:05to increase the difference in temperature between the heat source and the cooler surroundings.
17:15This idea has guided engineers for 200 years.
17:22Ultimately, a car engine is more efficient than a steam engine because it runs at a much hotter temperature.
17:29Jet engines are more efficient still thanks to the incredible temperatures they can run at.
17:38Karno had revealed that heat engines weren't just a clever invention.
17:43They were tapping into a deeper property of nature.
17:49They were exploiting the flow of energy between hot and cold.
18:02Karno had glimpsed the true nature of heat engines and, in the process, begun a new branch of science.
18:09But he would never see the impact his idea would have on the world.
18:16In 1832, a cholera epidemic spread through Paris.
18:20It was so severe it would kill almost 19,000 people.
18:25Now, back then there was no real scientific understanding of how the disease spread, so it must have been terrifying.
18:31Karno, undaunted by the risks, decided to study and document the spread of the disease.
18:38But, unfortunately, he contracted it himself and was dead a day later.
18:44He was just 36 years old.
18:46A lot of his precious scientific papers were burnt to stop the spread of contagion.
18:51And his ideas fell into temporary obscurity.
18:56It seems the world wasn't quite ready for Karno.
19:04Karno had made the first great contribution to the science of thermodynamics.
19:10But as the 19th century progressed, the study of heat, motion and energy began to grip the wider scientific community.
19:20Soon, it was realised that these ideas could do much more than simply explain how heat engines worked.
19:26Just as Leibniz had suspected with his notion of living force, these ideas were applicable on a much grander scale.
19:49By the mid-19th century, scientists and engineers had worked out very precisely how different forms of energy relate to
19:57each other.
19:58They measured how much of a particular kind of energy is needed to make a certain amount of a different
20:05kind.
20:06Let me give you an example.
20:08The amount of energy needed to heat 30 millilitres of water by 1 degree centigrade is the same as the
20:17amount of energy needed to lift this 12.5 kilogram weight by 1 metre.
20:26The deeper point here that people realised was that although mechanical work and heat may seem very different, they are
20:35in fact both facets of the same thing.
20:38Energy.
20:42This idea would come to be known as the first law of thermodynamics.
20:49The first law reveals that energy is never created or destroyed.
20:53It just changes from one form to another.
20:5919th century scientists realised this meant the total energy of the entire universe is actually fixed.
21:08Amazingly, there's a set amount of energy that just changes into many different forms.
21:14So, in a steam engine, energy isn't created. It's just changed from heat into mechanical work.
21:31But impressive though the first law is, it begged an enormous question.
21:36What exactly is going on when one form of energy changes into another?
21:42In fact, why does it do it at all?
21:52The answer would in part be found by German scientist Rudolf Clausius.
21:58And it would form the basis of what would become known as the second law of thermodynamics.
22:09Rudolf Clausius was a brilliant German physics student from Pomerania who studied in Berlin and at a ridiculously young age
22:21became a very brilliant professor in Berlin and then in Zurich at the new technology university set up there in
22:29Switzerland.
22:30And in the 1850s and in the 1850s, Clausius offered what is really the first coherent, full-blown mathematical analysis
22:41of how thermodynamics works.
22:48Clausius realised that not only was there a fixed amount of energy in the universe, but that the energy seemed
22:55to be following a very strict rule.
22:58Put simply, energy in the form of heat always moved in one particular direction.
23:10This insight of his is in fact one of the most important ideas in the whole of science.
23:15As Clausius put it, heat cannot of itself pass from a colder to a hotter body.
23:22This is a very intuitive idea.
23:25If left alone, this hot mug of tea will always cool down.
23:29What this means is that heat will pass from the hot mug, say, to my hand, and then again from
23:36my hand to my chest.
23:46This might seem completely obvious, but it was a crucial insight.
23:53The flow of heat was a one-way process that seemed to be built very fundamentally into the workings of
24:01the entire universe.
24:07Of course, objects can get hotter, but you always need to do something to them to make this happen.
24:17Left alone, energy seems to always go from being concentrated to being dispersed.
24:34One of my favourite statements in science was made by the biochemist Albert St. George, who said that science is
24:42all about seeing what everyone else has seen, but thinking what no one else has thought.
24:48And he, Rudolf Clausius, looked at the everyday world and saw what everyone else had seen, that heat does not
24:59flow spontaneously from a cold body to a hot body.
25:03It always goes the other way.
25:05But he didn't just say, ah, I see that.
25:09He actually sat down and thought about it.
25:11He actually sat down and thought about it.
25:19Clausius brought together all these ideas about how energy is transferred and put them into mathematical context.
25:27It could be summarised by this equation.
25:47Now, what Clausius did was introduce a new quantity he called entropy, this letter S.
25:54Basically what it's saying in the context of this equation is that as heat is transferred from hotter to colder
26:01bodies, entropy always increases.
26:11Entropy seemed to be a measure of how heat dissipates or spreads out.
26:17As hot things cool, their entropy increases.
26:22It appeared to Clausius that in any isolated system, this process would be irreversible.
26:39Clausius was so confident about his mathematics that he figured out that this irreversible process was going on out of
26:47the world.
26:49He speculated that the entropy of the entire universe had to be increasing towards a maximum and that there was
26:57nothing we could do to avoid this.
26:59This idea became known as the second law of thermodynamics and it turned out to be stranger and more beautiful,
27:07more universal than anything Clausius could have imagined.
27:21The second law of thermodynamics seemed to say that all things that gave off heat were in some way connected
27:29together.
27:33All things that gave off heat were part of an irreversible process that was happening everywhere.
27:41A process of spreading out and dispersing. A process of increasing entropy.
27:52It seemed that somehow the universe shared the same fate as a cup of tea.
28:01The wonderful thing about the Victorian scientists is that they could make these great leaps and that they could see
28:09that their study of thermometer in a beaker actually could be transferred, could be extrapolated, could be enlarged to encompass
28:19the whole universe.
28:39Despite the successes of thermodynamics, in the middle of the 19th century there was great debate and confusion about the
28:46subject.
28:47What exactly was this strange thing called entropy and why was it always increasing?
28:55Answering this question would take an incredible intellectual leap, but it would end up revealing the truth about energy and
29:03the many forms of order and disorder we see in the universe around us.
29:13Many scientists would tackle the mysterious concept of entropy, but one more than any other would shed light on the
29:21truth.
29:21He'd show what entropy really was and why over time it always must increase.
29:27His name was Ludwig Boltzmann and he was one of science's true revolutionaries.
29:45Boltzmann had been born in Vienna in 1844.
29:49It was a world of scientific and cultural certainty, but Boltzmann took little notice of the entrenched beliefs of his
29:56contemporaries.
29:57To him, the physical world was something best explored with an open mind.
30:06Boltzmann wasn't your stereotypical scientist.
30:09In fact, he had the kind of temperament that most people might associate with great artists.
30:15He was ruthlessly logical and analytical, yes, but while working he'd go through periods of intense emotion and these would
30:24be followed by terrible depressions which would leave him completely unable to think clearly.
30:37He had terrible sort of mental crises and breakdowns in which he really thought that the world was coming apart
30:46at the seams.
30:47And yet these were also accompanied by some of the most profound insights into the nature of our world.
30:56Outside of mathematics, Boltzmann was passionate about music and was captivated by the grand and dramatic operas of Wagner and
31:06the raw emotion of Beethoven.
31:10He was a brilliant pianist and could lose himself for hours in the works of his favourite composers, just as
31:17he could lose himself in deep mathematical theories.
31:29Boltzmann was a scientist guided by his emotions and instinct and also by his belief in the ability of mathematics
31:37to unlock the secrets of nature.
31:38It was these traits that would lead him to become one of the champions of a shocking and controversial new
31:46theory.
31:47One that would describe reality at the very smallest scales, far smaller than anything we could see with the naked
31:53eye.
31:56During the second half of the 19th century, a small group of scientists began speculating that at the smallest scales,
32:05the universe might operate very differently to our everyday experiences.
32:15If you could look close enough, it seemed possible that the universe might be made of tiny, hard particles in
32:24constant motion.
32:29The title of the book is品ic, is a result of this.
32:38Viewed in terms of atoms, heat would suddenly become a much less mysterious concept.
32:44Boltzmann and others saw that if an object was hot, it simply meant that its atoms were moving about more
32:51rapidly.
32:56Viewing the world as atoms seemed to be an immensely powerful idea.
33:03But this picture of the universe had one seemingly insurmountable problem.
33:11How could trillions and trillions of atoms,
33:14even in a tiny volume of gas, ever be studied?
33:18How could we come up with mathematical equations to describe all of this?
33:22After all, atoms are constantly bumping into each other,
33:26changing direction, changing speed.
33:28And there are just so many of them.
33:30It seemed almost an impossible problem.
33:34But then Boltzmann saw there was a way.
33:45Boltzmann saw more clearly than anyone
33:48that for physics to explain this new strata of reality,
33:53it had to abandon certainty.
34:04Instead of trying to understand and measure
34:07the exact movements of each individual atom,
34:11Boltzmann saw you could build working theories
34:13simply by using the probability
34:16that atoms would be travelling at certain speeds
34:19and in certain directions.
34:29Boltzmann had transported himself inside matter.
34:35He'd imagined a world beneath our everyday reality
34:39and found a mathematics to describe it.
34:43It would be here, at this scale,
34:46that Boltzmann would one day
34:48manage to unlock energy's deepest secret,
34:52despite the widespread hostility to his theories.
35:02Boltzmann's ideas were highly, highly controversial.
35:06And you have to remember that, you know,
35:08today we take atoms for granted.
35:10But the reason we take atoms for granted
35:13is precisely because Boltzmann's mathematics
35:17married up so beautifully with experiment.
35:43.
35:47One of the most surprising aspects of this story is that many of Boltzmann's contemporaries
35:53viewed his ideas about atoms with intense hostility.
36:02Today the existence of atoms, the idea that all matter is composed of tiny particles is
36:08something we accept without question.
36:09But back in Boltzmann's time there were notable eminent physicists who just didn't buy it.
36:16Why would they?
36:17No one had ever seen an atom and probably no one ever would.
36:21How could these particles be considered as real?
36:35After one of Boltzmann's lectures of atomic theory in Vienna, the great Austrian physicist
36:40Ernst Mach stood up and said simply, I don't believe that atoms exist.
36:46It was both cutting and dismissive, and for such a comment to come from a highly regarded
36:52scientist like Ernst Mach, it would have been doubly hurtful.
37:04They argued that no, atoms don't exist.
37:07They're names, labels, convenient fictions, calculating devices.
37:13They don't really exist.
37:15We can't observe them.
37:16No one's ever seen one.
37:18And for that reason, so Boltzmann's critics said, he was a fantasist.
37:26But Boltzmann was right.
37:29He peered deeper into reality than anyone else had dared, and seen that the universe could
37:35be built from the atomic hypothesis, and understood through the mathematics of probability.
37:41The foundations and certainty of 19th century science were beginning to crumble.
37:55As Boltzmann stared into his brave new world of atoms, he began to realise his new vision
38:02of the universe contained within it an explanation to one of the biggest mysteries in science.
38:10Boltzmann saw that atoms could reveal why the second law of thermodynamics was true, why
38:16nature was engaged in an irreversible process.
38:20Atoms had the power to reveal what entropy really was, and why it must always increase.
38:32Boltzmann understood that all objects, these walls, you, me, the air in this room, are made
38:38up of much tinier constituents.
38:42Basically, everything we see is an assembly of trillions and trillions of atoms and molecules.
38:48And this was the key to his insight about entropy and the second law.
38:59Boltzmann saw what Clausius could not.
39:02The real reason why a hot object left alone will always cool down.
39:08Imagine a lump of hot metal.
39:12The atoms inside it are jostling around.
39:16But as they jostle, the atoms at the edge of the object transfer some of their energy
39:22to the atoms in the surface of the table.
39:28These atoms then bump into their neighbours, and in this way the heat energy slowly and very
39:35naturally spreads out and disperses.
39:40The whole system has gone from being in a very special ordered state, with all the energy
39:46concentrated in one place, to a disordered state, where the same amount of energy is now distributed
39:53among many more atoms.
39:57Boltzmann's brilliant mind saw this whole process could be described mathematically.
40:04Boltzmann's great contribution was that, although we can talk in rather sort of casual terms
40:12about things getting worse and disorder increases, the great contribution of Boltzmann is that
40:19he could put numbers to it.
40:21And so he was able to derive a formula which enabled you to calculate the disorder of a system.
40:36This is Boltzmann's famous equation.
40:39It will be his enduring contribution to science.
40:42So much so, it was engraved on his tombstone in Vienna.
40:47What this equation means in essence is that there are many more ways for things to be messy and disordered
40:55than there are for them to be tidy and ordered.
41:01That's why, left to itself, the universe will always get messier.
41:13Things will move from order to disorder.
41:31It's a law that applies to everything, from a drop jug to a burning star.
41:39A hot cup of tea to the products that we consume every day.
41:51All of this is an expression of the universe's tendency to move from order to disorder.
42:07Disorder is the fate of everything.
42:18Clausius had shown that something he called entropy was getting bigger all the time.
42:27Now, Boltzmann had revealed what this really meant.
42:31Entropy was in fact a measure of the disorder of things.
42:41Energy is crumbling away. It's crumbling away now as we speak.
42:47So the second law is all about entropy increasing.
42:51Which is just a technical way of saying that things get worse.
42:55It's almost 21st century ever before we move from a moment.
42:57Do it is a natural figure.
42:57Do it is a real nightmare.
43:19Do it.
43:19If you'd like it to me...
43:19Does it?
43:20If you'd like it to me...
43:20Go to my navy.
43:23If you'd like it.
43:23The Chief of theładist.
43:23In fact, you've got the most imperfections.
43:24You can't read the most.
43:24passionate and romantic sensibility and his belief in the power of mathematics
43:29had led him to one of the most important discoveries in the history of science.
43:33But those very same intense emotions had a dark and ultimately self-destructive side.
43:47Throughout his life, Boltzmann had been prone to severe bouts of depression.
43:52Sometimes these were induced by the criticisms of his theories and sometimes they just happened.
43:59In 1906, he was forced to take a break from his studies in Vienna during a particularly bad episode.
44:17In September 1906, Boltzmann and his family were on holiday in Duino, near Trieste in Italy.
44:25While his wife and family were out at the beach, Boltzmann hanged himself, bringing his short time in our universe
44:32to an abrupt end.
44:33But perhaps the saddest aspect of Boltzmann's story is that within just a few years of his death,
44:40his ideas that had been attacked and ridiculed during his lifetime were finally accepted.
44:46What's more, they became the new scientific orthodoxy.
44:59In the end, there is no escaping entropy.
45:03It's the ultimate move from order to decay and disorder that rules us all.
45:13Boltzmann's equation contains within it the mortality of everything from a china jug to a human life to the universe
45:23itself.
45:33The process of change and degradation is unavoidable.
45:38The second law says the universe itself must one day reach a point of maximum entropy, maximum disorder.
45:49The universe itself must one day die.
45:59The universe itself must one day die.
46:27If everything degrades, if everything becomes disordered, you might be wondering how it is that we exist.
46:37How exactly did the universe manage to create the exquisite complexity and structure of life on Earth?
46:47Contrary to what you might think, it's precisely because of the second law that all this exists.
46:54The great disordering of the cosmos gives rise to its complexity.
47:04It's possible to harness this natural flow from order to disorder.
47:09To tap into the process and generate something new.
47:14To create new order, new structure.
47:17It's what the early steam pioneers had unwittingly hit upon with their engines.
47:21And it's what makes everything we deem special in our world.
47:25From this car, to buildings, to works of art, even to life itself.
47:49The engine of my car, like all engines, is designed to exploit the second law.
47:54It starts out with something nice and ordered, like this petrol, stuffed full of energy.
47:59But when it's ignited in the engine, it turns this compact liquid into a mixture of gases 2,000 times
48:06greater in volume.
48:08Not to mention dumping heat and sound into the environment.
48:12It's turning order into disorder.
48:24What's so spectacularly clever about my car is that it can harness that dissipating energy.
48:30It can siphon off a small bit of it and use it for a more ordered process.
48:35Like driving the pistons which turn the wheels.
48:37That's what engines do.
48:39They tap into that flow from order to disorder and do something useful.
48:50But it's not just cars.
48:53Evolution has designed our bodies to work thanks to the very same principle.
48:57If I eat this chocolate bar packed full of nice ordered energy, my body processes it and turns it into
49:06more disordered energy that powers itself off the proceeds.
49:16Both cars and humans power themselves by tapping into the great cosmic flow from order to disorder.
49:27Although overall the world is falling apart in disorder, it's doing it in a seriously interesting way.
49:38It's like a waterfall that is rushing down.
49:43But the waterfall throws up a spray of structure.
49:48And that spray of structure might be you or me or daffodil or whatever.
49:55So you can see that the unwinding of the universe, this collapse into disorder, can in fact be constructive.
50:09Steam engines, power stations, life on Earth.
50:17All of these things harness the cosmic flow from order to disorder.
50:31The reason the Earth now looks the way it does is because we've learnt to harness the disintegrating energy of
50:39the universe to maintain and improve our small pocket of order.
50:48But as humankind has evolved, we've had to find new pieces of concentrated energy we can break down to drive
50:56the ever more demanding construction of our technologies, our cities and our society.
51:05From food to wood to fossil fuels, over human history, we've discovered ever more concentrated forms of energy to unlock
51:14in order to flourish.
51:27Now in the 21st century, we're on the cusp of harnessing the ultimate form of concentrated energy.
51:35The stuff that powers the sun.
51:40Hydrogen.
51:40Hydrogen.
51:45Hydrogen.
51:48Hydrogen.
51:50Hydrogen.
51:54Hydrogen.
51:55Hydrogen.
51:55This is the Cullum Centre for Fusion Energy in Oxford.
51:58And at this facility, they are attempting to recreate a star here on Earth.
52:05But as you might imagine, creating and containing a small star is not an easy process.
52:17It requires many hundreds of people and some extremely ingenious technology.
52:24This machine is called a tokamak, and it's designed to extract an ancient type of highly
52:31concentrated energy, the ordered energy of hydrogen atoms.
52:39These tiny packets of energy were forged in the early universe, just three minutes after
52:46the moment of creation itself.
52:53Now using the tokamak, we can extract the concentrated energy contained in these atoms by fusing them
53:05together.
53:06Inside the tokamak machine, two types of hydrogen gas, deuterium and tritium, are mixed together
53:14into a super hot state called a plasma.
53:18Now when running, this plasma can reach the incredible temperature of 150 million degrees.
53:25Large magnets in the wall of the tokamak contain the plasma and stop it from touching the sides
53:30where it can cool down.
53:32Now when it gets hot enough, the two types of hydrogen atoms fuse together to form helium
53:38and spit out a neutron.
53:40Now these neutrons fly out of the plasma and hit the walls of the tokamak.
53:45But they carry energy.
53:47And the hope is that this energy can one day be used to heat up water, turn it into steam,
53:53to drive a turbine and generate electricity.
53:55Essentially, for a brief moment, inside the tokamak, a small donut shaped star is created.
54:16The problem is, it's extremely difficult to sustain the fusion reaction for long enough to harvest
54:23the energy from it.
54:24And that's what the scientists at Cullum are working to perfect.
54:29It's a sort of boundary between physics and engineering.
54:32How do we hold on to this very, very hot thing, which is the plasma?
54:37And how do we optimise the way, the performance of this plasma?
54:42So what we really want is that the particles stay in there for as long as it's all possible
54:46to maximise their chance of hitting each other.
54:50We are trying to push this to the limits with what we have available in this machine.
54:57And whatever we can learn to understand this plasma better will also allow us to design
55:01a better machine in the future.
55:03You can see, although it happens several times a day, oh, here we go.
55:07The scientists here all gather round the screens.
55:11Ah, OK, it's about to come on.
55:47What the Tokamak is doing...
55:49is mining the fertile ashes of the Big Bang, extracting concentrated energy captured at
55:57the beginning of time.
56:00As hydrogen is the most abundant element in the universe, if future machines can sustain
56:06fusion reactions, they offer us the possibility of almost unlimited energy.
56:22From a science that began as the by-products of questions about steam engines, thermodynamics
56:29has had a staggering impact on all our lives.
56:33It has shown us why we must consume concentrated energy to stay alive, and has revealed to us
56:41how the universe itself is likely to end.
56:47Looking at the Earth at night reveals how one seemingly simple idea transformed the planet.
56:55What is the world's enrichment, how the planet is being created by the planet?
56:57What is the world's enrichment, how the planet is being created by the planet?
57:14Over the past 300 years, we have developed ever more ingenious ways to harness the concentrated energy from the world
57:22around us.
57:23But all our efforts and achievements are quite insignificant
57:27when viewed from the perspective of the wider universe.
57:31As far as it's concerned, all we're doing is trying to preserve
57:34this tiny pocket of order in a cosmos that's falling apart.
57:49Although we can never escape our ultimate fate,
57:52the laws of physics have allowed us this brief, beautiful, creative moment
57:59in the great cosmic unwinding.
58:02My hope is that by understanding the universe in ever greater detail,
58:07we can stretch this moment for many millions,
58:11maybe even billions of years to come.
58:27The concept of information is a very strange one.
58:31It's actually a very difficult idea to get your head round.
58:34But in the journey to try and understand it,
58:38scientists would discover that information is actually
58:41a fundamental part of our universe.
58:55And there's more Big Science here on BBC HD at 7 o'clock tomorrow
58:59with the science of chance in Tales You Win.
59:04The End
59:04The End
59:04The End
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