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  • How did humans acquire the power to transform the planet like this?

  • Looking at the earth at night

  • reveals to us just how successful we've been

  • in harnessing and manipulating energy

  • and how important it is to our existence.

  • Energy is vital to us all.

  • We use it to build the structures that surround and protect us.

  • We use it to power our transport and light our homes.

  • And even more crucially, energy is essential for life itself.

  • Without the energy we get from the food we eat, we'd die.

  • But what exactly is energy?

  • And what makes it so useful to us?

  • In attempting to answer these questions,

  • scientists would come up with a strange set of laws

  • that would link together everything, from engines, to humans, to stars.

  • It turns out that energy, so crucial to our daily lives

  • also helps us make sense of the entire universe.

  • This film is the intriguing story

  • of how we discovered the rules that drive the universe.

  • It is the story of how we realised

  • that all forms of energy are destined to degrade and fall apart.

  • To move from order to disorder.

  • It's the story of how this amazing process

  • has been harnessed by the universe

  • to create everything that we see around us.

  • Over the course of human history,

  • we've come up with all sorts of different ways

  • of extracting energy from our environment.

  • Everything from picking fruit,

  • to burning wood, to sailing boats, to waterwheels.

  • But around 300 years ago, something incredible happened.

  • Humans developed machines

  • that were capable of processing extraordinary amounts of energy

  • to carry out previously unimaginable tasks.

  • This happened thanks to many people and for many different reasons,

  • but I'd like to begin this story

  • with one of the most intriguing characters

  • in the history of science.

  • One of the first to attempt to understand energy.

  • Gottfried Leibniz was a diplomat, scientist, philosopher and genius.

  • He was forever trying to understand the mechanisms

  • that made the universe work.

  • Leibniz like several of his great contemporaries

  • was absolutely convinced that the world we see around us

  • is a vast machine designed by a powerful and wise person.

  • And if you could understand how machines worked,

  • you could therefore understand how the universe

  • and the principles that had been used to make the universe worked as well.

  • So there was an extremely close relationship for Leibniz

  • between theology and philosophy on the one hand

  • and engineering and mechanics on the other.

  • It was this relationship between philosophy and engineering

  • that in 1676 would lead him to investigate

  • what at first sight seemed to be a very simple question.

  • What happens when objects collide?

  • This is was what Leibniz

  • and many of his contemporaries were grappling with.

  • So when these two balls bump into each other,

  • the movement of one gets transferred to the other.

  • It's as though something's been passed between them

  • and this that Leibniz called the living force.

  • He thought of it as a stuff,

  • as a real physical substance that gets exchanged during collisions.

  • Leibniz argued that the world is a living machine

  • and that inside the machine,

  • there is a quantity of living force put there by God at the Creation

  • that will stay the same forever.

  • So the amount of living force in the world will be conserved.

  • The puzzle was to define it.

  • Leibnitz would soon find a simple mathematical way

  • to describe the living force.

  • But he would also see something else.

  • EXPLOSION

  • He realised that in gunpowder, fire and steam,

  • his living force was being released in violent and powerful ways.

  • EXPLOSION

  • If this could be harnessed,

  • it could give humankind unimaginable power.

  • Leibniz would soon become fascinated

  • with ways of capturing the living force.

  • A prolific letter writer, Leibniz struck up correspondence

  • with a young French scientist called Denis Papin.

  • As they corresponded, Leibniz and Papin realised

  • the living force released in certain situations

  • could indeed be harnessed.

  • Heat could be converted in to some form of useful action.

  • But how far could this idea be taken?

  • Papin was in no doubt.

  • This is an extract from his letter to Leibniz...

  • "I can assure you that the more I go forward,

  • "the more I find reason to think highly of this invention,

  • "which in theory, may augment the powers of man to infinity.

  • "But in practice, I believe I can say without exaggeration,

  • "that one man by this means

  • "will be able to do as much as 100 others can do without it."

  • Now, you might expect me at this point to tell you

  • that Leibniz and Papin changed the world forever.

  • Well, they hadn't.

  • Their ideas had been profound and far reaching, yes,

  • but they hadn't really moved things forward.

  • For that, you need something much more tangible.

  • You need innovation, industry.

  • You need countless skilled workers and craftsmen

  • who are going to apply these ideas,

  • to experiment with them in novel and new ways.

  • Well, in the century that followed Leibniz and Papin,

  • this would take place in the most dramatic way imaginable.

  • 150 years after Leibniz and Papin's discussions,

  • the living force had been harnessed in spectacular ways.

  • The machines they dreamed of had become a reality.

  • Steam engines were now the cutting edge of 19th century technology.

  • If you look at steps in civilisation,

  • then one great step was the steam engine, because it replaced muscle,

  • animal muscle, including our muscle, by steam power.

  • And the steam power was effectively limitless

  • and hugely important to doing almost unimaginable things.

  • But steam technology would do more than just transform human society.

  • It would uncover the truth about what Leibniz had called

  • the living force and reveal new insights

  • about the workings of our universe.

  • This is Crossness in south-east London.

  • It's an incredible industrial cathedral,

  • home to some of the most impressive Victorian steam engines ever built.

  • Constructed in 1854, Crossness houses four huge engines

  • that once required 5,000 tonnes of coal each year

  • to drive their 47-tonne beams.

  • Everything about this place seems to have been built to impress.

  • From the lavish ironwork -

  • the grand pillars like something out of a Greek or Roman temple.

  • It's the kind of effort you'd think would be lavished

  • on a luxury ocean liner for the rich and famous.

  • And yet this place was built to process sewage.

  • Although only a few workers and engineers would see inside it,

  • steam had become

  • such a vital part of Britain's power and economic prosperity

  • that it was afforded almost religious respect.

  • But for all the great success and immense power

  • that engines were bestowing on their creators

  • there was still a great deal of confusion and mystery

  • surrounding exactly how and why they worked.

  • In particular questions like, "How efficient could they be made?"

  • "Were there limits to their power?"

  • Ultimately, people wanted to know

  • just what might it be possible to achieve with steam.

  • The reason these questions persisted was simple almost no-one

  • had understood the fundamental nature of the steam engine.

  • Very few were aware of the cosmic principle which underpinned it.

  • These great lumbering machines we think of as the early steam engines

  • actually were the seed of understanding

  • of everything that goes on in the universe.

  • As unlikely as it sounds,

  • steam engines held within them the secrets of the cosmos.

  • This is the Chateau de Vincennes in Paris.

  • Events here would motivate one man's journey to uncover the cosmic truth

  • about the steam engine, and help to create a new science.

  • The science of heat and motion. Thermo-dynamics.

  • In March 1814, during the Napoleonic wars,

  • when Napoleon and his armies where fighting elsewhere,

  • Paris itself came under sustained attack

  • from the combined forces of Russia, Prussia and Austria.

  • Citizens were deployed around key locations to protect them.

  • This chateau was being defended by a group of inexperienced students

  • who were forced to retreat under sustained artillery fire.

  • One of them was a brilliant young scientist and soldier.

  • His name was Nicolas Leonard Sadi Carnot

  • and the humiliation he felt personally

  • would drive him and motivate him

  • to uncover a profound insight into how all engines work.

  • Carnot came from a highly-respected military family.

  • After the French defeat here and elsewhere around Europe,

  • he became determined to reclaim French pride.

  • What really bothered Carnot was the technological superiority

  • that France's enemies seemed to possess.

  • And Britain, in particular, had this huge advantage

  • both militarily and economically

  • because of its mastery of steam power.

  • So Carnot vowed to really understand how steam engines work

  • and use that knowledge for the benefit of France.

  • He says absolutely explicitly that if you could take away

  • steam engines from Britain

  • then the British Empire would collapse.

  • And he's writing in the wake of French military defeat

  • and he proposes to analyse,

  • literally, the source of British power

  • by analysing the way in which fire and heat engines work.

  • Living on half-pay with his brother Hippolyte

  • in a small apartment in Paris,

  • in 1824 Carnot wrote the now legendary

  • Reflections On The Motive Power Of Fire.

  • In just under 60 pages,

  • he developed and abstracted the fundamental way

  • in which all heat engines work.

  • Carnot saw that all heat engines

  • comprised of a hot source in cooler surroundings.

  • Now, Carnot believed heat was some kind of substance

  • that would flow like water from the hot to the cool.

  • And just like water falling from a height

  • the flow of heat could be tapped to do useful work.

  • Carnot's crucial insight

  • was to show that to make any heat engine more efficient

  • all you had to do was to increase the difference in temperature

  • between the heat source and cooler surroundings.

  • This idea has guided engineers for 200 years.

  • Ultimately, a car engine is more efficient than a steam engine

  • because it runs at a much hotter temperature.

  • Jet engines are more efficient still

  • thanks to the incredible temperatures they can run at.

  • Carnot had revealed

  • that heat engines weren't just a clever invention.

  • They were tapping into a deeper property of nature.

  • They were exploiting the flow of energy

  • between hot and cold.

  • Carnot had glimpsed the true nature of heat engines and, in the process,

  • begun a new branch of science.

  • But he would never see the impact his idea would have on the world.

  • In 1832, a cholera epidemic spread through Paris.

  • It was so severe, it would kill almost 19,000 people.

  • Now, back then, there was no real scientific understanding

  • of how the disease spread, so it must have been terrifying.

  • Carnot undaunted by the risks,

  • decided to study and document the spread of the disease.

  • But, unfortunately, he contracted it himself and was dead a day later.

  • He was just 36 years old.

  • A lot of his precious scientific papers were burned

  • to stop the spread of the contagion

  • and his ideas fell into temporary obscurity.

  • It seems the world wasn't quite ready for Carnot.

  • Carnot had made the first great contribution

  • to the science of thermodynamics.

  • But as the 19th century progressed the study of heat, motion and energy

  • began to grip the wider scientific community.

  • Soon, it was realised these ideas could do much more

  • than simply explain how heat engines worked.

  • Just as Leibniz had suspected with his notion of living force,

  • these ideas were applicable on a much grander scale.

  • By the mid 19th century,

  • scientists and engineers had worked out very precisely

  • how different forms of energy relate to each other.

  • They measured how much of a particular kind of energy is needed

  • to make a certain amount of a different kind.

  • Let me give you an example.

  • The amount of energy needed to heat 30ml of water

  • by one degree centigrade

  • is the same as the amount of energy needed

  • to lift this 12.5kg weight by one metre.

  • The deeper point here that people realised

  • was that although mechanical work and heat may seem very different,

  • they are, in fact, both facets of the same thing - energy.

  • This idea would come to be known as the first law of thermodynamics.

  • The first law reveals that energy is never created or destroyed.

  • It just changes from one form to another.

  • 19th Century scientists realised this meant the total energy

  • of the entire universe is actually fixed.

  • Amazingly, there's a set amount of energy

  • that just changes into many different forms.

  • So, in a steam engine, energy isn't created -

  • it's just changed from heat into mechanical work.

  • But impressive though the first law is, it begged an enormous question -

  • what exactly is going on when one form of energy changes into another?

  • In fact, why does it do it at all?

  • The answer would, in part, be found by German scientist Rudolf Clausius.

  • And it would form the basis what would become known

  • as the second law of thermodynamics.

  • Rudolf Clausius was a brilliant German physics student

  • from Pomerania

  • who studied in Berlin

  • and at a ridiculously young age became a very brilliant professor

  • in Berlin and then in Zurich

  • at the new technology university set up there in Switzerland.

  • In the 1850s and 60s, Clausius offered what was really

  • the first, coherent, full-blown, mathematical analysis

  • of how thermodynamics works.

  • Clausius realised that not only was there

  • a fixed amount of energy in the universe

  • but that the energy seemed to be following a very strict rule.

  • Put simply, energy in the form of heat

  • always moved in one particular direction.

  • This insight of his is

  • in fact one of the most important ideas in the whole of science.

  • As Clausius put it,

  • "Heat cannot of itself pass from a colder to a hotter body".

  • This is a very intuitive idea.

  • If left alone, this hot mug of tea will always cool down.

  • What this means is that heat will pass from the hot mug

  • say to my hand and then again from my hand to my chest.

  • This might seem completely obvious but it was a crucial insight.

  • The flow of heat was a one-way process that seemed to be built

  • very fundamentally into the workings of the entire universe.

  • Of course, objects can get hotter

  • but you always need to do something to them to make this happen.

  • Left alone, energy seems to always go from being concentrated

  • to being dispersed.

  • One of my favourite statements in science was made

  • by the biochemist called Albert St George who said that,

  • "Science is all about seeing what everyone else has seen,

  • "but thinking what no-one else has thought."

  • And he, Rudolf Clausius, looked at the everyday world

  • and saw what everyone else had seen,

  • that heat does not flow spontaneously from a cold body to a hot body.

  • It always goes the other way.

  • But he didn't just say, "Ah, I see that."

  • He actually sat down and thought about it.

  • Clausius brought together all these ideas about how energy

  • is transferred and put them into mathematical context.

  • It could be summarised by this equation.

  • Now, what Clausius did was introduce a new quantity he called entropy.

  • This letter S.

  • Basically, what it's saying in the context of this equation

  • is that as heat is transferred from hotter to colder bodies,

  • entropy always increases.

  • Entropy seemed to be a measure of how heat dissipates or spreads out.

  • As hot things cool, their entropy increases.

  • It appeared to Clausius that in any isolated system

  • this process would be irreversible.

  • Clausius was so confident about his mathematics

  • that he figured out that this irreversible process

  • was going on out there in the wider cosmos.

  • He speculated that the entropy of the entire universe

  • had to be increasing toward a maximum

  • and there was nothing we could do to avoid this.

  • This idea became known as the second law of thermodynamics

  • and it turned out to be stranger, and more beautiful,

  • more universal than anything that Clausius could have imagined.

  • The second law of thermodynamics seemed to say that all things

  • that gave off heat were, in some way, connected together.

  • All things that gave off heat were part of an irreversible process

  • that was happening everywhere.

  • A process of spreading out and dispersing.

  • A process of increasing entropy.

  • It seemed that, somehow, the universe shared the same fate

  • as a cup of tea.

  • The wonderful thing about the Victorian scientists

  • is that they could make these great leaps

  • and they could see that their study of a thermometer in a beaker

  • actually could be transferred... could be extrapolated,

  • could be enlarged to encompass the whole universe.

  • Despite the successes of thermodynamics,

  • in the middle of the 19th century,

  • there was great debate and confusion about the subject.

  • What exactly was this strange thing called entropy

  • and why was it always increasing?

  • Answering this question would take an incredible intellectual leap

  • but it would end up revealing the truth about energy

  • and the many forms of order and disorder

  • we see in the universe around us.

  • Many scientists would tackle the mysterious concept of entropy.

  • But one more than any other would shed light on the truth.

  • He'd show what entropy really was

  • and why, over time, it always must increase.

  • His name was Ludwig Boltzmann

  • and he was one science's true revolutionaries.

  • Boltzmann had been born in Vienna in 1844.

  • It was a world of scientific and cultural certainty.

  • But Boltzmann took little notice

  • of the entrenched beliefs of his contemporaries.

  • To him, the physical world

  • was something best explored with an open mind.

  • Boltzmann wasn't your stereotypical scientist.

  • In fact, he had the kind of temperament

  • most people might associate with great artists.

  • He was ruthlessly logical and analytical, yes,

  • but while working, he'd go through periods of intense emotion

  • followed by terrible depressions

  • which would leave him completely unable to think clearly.

  • He had terrible

  • mental crises and breakdowns

  • in which he really thought that the world was coming apart at the seams

  • and yet these were also accompanied

  • by some of the most profound insights into the nature of our world.

  • Outside of mathematics, Boltzmann was passionate about music

  • and was captivated by the grand and dramatic operas of Wagner

  • and the raw emotion of Beethoven.

  • He was a brilliant pianist

  • and could lose himself for hours in the works of his favourite composers

  • just as he could lose himself in deep mathematical theories.

  • MUSIC: Beethoven's 5th Symphony - First Movement.

  • Boltzmann was a scientist guided by his emotions and instinct

  • and also by his belief in the ability of mathematics

  • to unlock the secrets of nature.

  • It was these traits that would lead him to become

  • one of the champions of a shocking and controversial new theory.

  • One that would describe reality at the very smallest scales.

  • Far smaller than anything we could see with the naked eye.

  • During the second half of the 19th century, a small group of scientists

  • began speculating that, at the smallest scales,

  • the universe might operate very differently

  • to our everyday experiences.

  • If you could look close enough, it seemed possible that the universe

  • might be made of tiny, hard particles, in constant motion.

  • Viewed in terms of atoms

  • heat would suddenly become a much less mysterious concept.

  • Boltzmann and others saw that if an object was hot

  • it simply meant that its atoms were moving about more rapidly.

  • Viewing the world as atoms seemed to be an immensely powerful idea.

  • But this picture of the universe

  • had one seemingly insurmountable problem.

  • How could trillions and trillions of atoms,

  • even in a tiny volume of gas, ever be studied?

  • How could we come up with mathematical equations

  • to describe all of this?

  • After all, atoms are constantly bumping into each other,

  • changing direction and speed, and there are just so many of them.

  • It seemed almost an impossible problem.

  • But then Boltzmann saw there was a way.

  • Boltzmann saw more clearly than anyone

  • that for physics to explain this new strata of reality

  • it had to abandon certainty.

  • Instead of trying to understand and measure the exact movements

  • of each individual atom, Boltzmann saw you could build working theories

  • simply by using the probability that atoms would be travelling

  • at certain speeds and in certain directions.

  • Boltzmann had transported himself inside matter.

  • He had imagined a world beneath our everyday reality

  • and found a mathematics to describe it.

  • It would be here at this scale that Boltzmann would one day manage

  • to unlock energy's deepest secret -

  • despite the widespread hostility to his theories.

  • Boltzmann's ideas were highly, highly controversial.

  • And you have to remember that today we take atoms for granted.

  • But the reason we take atoms for granted is precisely because

  • Boltzmann's mathematics married up so beautifully with experiments.

  • One of the most surprising aspects of this story is that

  • many of Boltzmann's contemporaries viewed his ideas about atoms

  • with intense hostility.

  • Today the existence of atoms,

  • the idea that all matter is composed of tiny particles,

  • is something we accept without question.

  • But back in Boltzmann's time

  • there were notable, eminent physicists who just didn't buy it.

  • Why would they?

  • No-one had ever seen an atom and probably no-one ever would.

  • How could these particles be considered as real?

  • After one of Boltzmann's lectures on atomic theory in Vienna

  • the great Austrian physicist Ernst Mach stood up

  • and said simply, "I don't believe that atoms exist!"

  • It was both cutting and dismissive.

  • And for such a comment to come from a highly regarded scientist

  • like Ernst Mach, it would have been doubly hurtful.

  • They argued that, "No, atoms don't exist."

  • They're names, labels,

  • convenient fictions, calculating devices.

  • They don't really exist. We can't observe them.

  • No-one's ever seen one.

  • And for that reason, so Boltzmann's critics said, he was a fantasist.

  • But Boltzmann was right.

  • He had peered deeper into reality than anyone else had dared,

  • and seen that the universe could be built from the atomic hypothesis

  • and understood through the mathematics of probability.

  • The foundations and certainty of 19th century science

  • were beginning to crumble.

  • As Boltzmann stared into his brave new world of atoms

  • he began to realise his new vision of the universe contained within it

  • an explanation to one of the biggest mysteries in science.

  • Boltzmann saw atoms could reveal why the second law of thermodynamics

  • was true, why nature was engaged in an irreversible process.

  • Atoms had the power to reveal what entropy really was

  • and why it must always increase.

  • Boltzmann understood that all objects these walls,

  • you, me, the air in this room, are made up of much tinier constituents.

  • Basically, everything we see is an assembly

  • of trillions and trillions of atoms and molecules.

  • And this was the key to his insight about entropy and the second law.

  • Boltzmann saw what Clausius could not.

  • The real reason why a hot object left alone will always cool down.

  • Imagine a lump of hot metal.

  • The atoms inside it are jostling around.

  • But as they jostle, the atoms at the edge of the object

  • transfer some of their energy to the atoms on the surface of the table.

  • These atoms then bump into their neighbours, and in this way,

  • the heat energy slowly and very naturally spreads out and disperses.

  • The whole system has gone from being in a special, ordered state

  • with all the energy concentrated in one place,

  • to a disordered state

  • where the same amount of energy is distributed amongst many more atoms.

  • Boltzmann's brilliant mind

  • saw this whole process could be described mathematically.

  • Boltzmann's great contribution was that,

  • although we can talk in rather sort of casual terms,

  • about things getting worse, and disorder increases,

  • the great contribution of Boltzmann is that he could put numbers to it.

  • So he was able to derive a formula which enabled you

  • to calculate the disorder of the system.

  • This is Boltzmann's famous equation.

  • It would be his enduring contribution to science,

  • so much so, it was engraved on his tombstone in Vienna.

  • What this equation means in essence

  • is there are many more ways for things to be messy and disordered

  • than there are for them to be tidy and ordered.

  • That's why, left to itself, the universe will always get messier.

  • Things will move from order to disorder.

  • It's a law that applies to everything

  • from a dropped jug to a burning star.

  • A hot cup of tea to the products that we consume every day.

  • All of this is an expression of the universe's tendency

  • to move from order to disorder.

  • Disorder is the fate of everything.

  • Clausius had shown that something he called entropy

  • was getting bigger all the time.

  • Now Boltzmann had revealed what this really meant

  • entropy was in fact a measure of the disorder of things.

  • Energy is crumbling away.

  • It's crumbling away now as we speak.

  • So the second law is all about entropy increasing.

  • It's just a technical way of saying things get worse.

  • Boltzmann's passionate and romantic sensibility

  • and his belief in the power mathematics

  • had led him to one of the most important discoveries

  • in the history of science.

  • But those very same intense emotions

  • had a dark and ultimately self-destructive side.

  • Throughout his life

  • Boltzmann had been prone to severe bouts of depression.

  • Sometimes these were induced by the criticisms of his theories

  • and sometimes they just happened.

  • In 1906, he was forced to take a break from his studies in Vienna

  • during a particularly bad episode.

  • In September 1906, Boltzmann and his family were on holiday

  • in Duino, near Trieste in Italy.

  • While his wife and family were out at the beach,

  • Boltzmann hanged himself,

  • bringing his short time in our universe to an abrupt end.

  • Perhaps the saddest aspect of Boltzmann's story

  • is that, within a few short years of his death,

  • his ideas that had been attacked and ridiculed during his life,

  • were finally accepted.

  • What's more, they became the new scientific orthodoxy.

  • In the end there is no escaping entropy it is the ultimate move

  • from order, to decay and disorder, that rules us all.

  • Boltzmann's equation contains within it the mortality of everything

  • from a china jug to a human life to the universe itself.

  • The process of change and degradation is unavoidable.

  • The second law says the universe itself must one day

  • reach a point of maximum entropy, maximum disorder.

  • The universe itself must one day die.

  • If everything degrades, if everything becomes disordered

  • you might be wondering how is it that WE exist.

  • How exactly did the universe manage to create

  • the exquisite complexity and structure of life on earth?

  • Contrary to what you might think

  • it's precisely because of the second law that all this exists.

  • The great disordering of the cosmos gives rise to its complexity.

  • It's possible to harness the natural flow

  • from order to disorder, to tap into the process

  • and generate something new, to create new order and new structure.

  • It's what the early steam pioneers had unwittingly hit upon

  • with their engines

  • and it's what makes everything we deem special in our world -

  • from this car, to buildings, to works of art, even to life itself.

  • The engine of my car, like all engines,

  • is designed to exploit the second law.

  • It starts out with something nice and ordered like this petrol

  • stuffed full of energy.

  • But when it is ignited in the engine it turns this compact liquid

  • into a mixture of gases 2,000 times greater in volume -

  • not to mention dumping heat and sound into the environment.

  • It's turning order to disorder.

  • What's so spectacularly clever about my car

  • is that it can harness that dissipating energy.

  • It can siphon off a small bit of it

  • and use it to run a more ordered process

  • like driving the pistons which turn the wheels. That's what engines do.

  • They tap into that flow from order to disorder

  • and do something useful.

  • But it's not just cars.

  • Evolution has designed our bodies to work

  • thanks to the very same principle.

  • If I eat this chocolate bar

  • packed full of nice, ordered energy,

  • my body processes it and turns it into more disordered energy

  • but powers itself off the proceeds.

  • Both cars and humans power themselves by tapping into

  • the great cosmic flow from order to disorder.

  • Although overall the world is falling apart in disorder

  • it is doing it in a seriously interesting way.

  • It's like a waterfall that is rushing down,

  • but the waterfall throws up a spray of structure

  • and that spray of structure might be you or me or a daffodil or whatever.

  • So you can see that the unwinding of the universe,

  • this collapse into disorder, can in fact be constructive.

  • Steam engines,

  • power stations,

  • life on earth -

  • all of these things harness the cosmic flow

  • from order to disorder.

  • The reason the earth now looks the way it does

  • is because we've learnt to harness the disintegrating energy

  • of the universe to maintain and improve our small pocket of order.

  • But as humankind has evolved,

  • we've had to find new pieces of concentrated energy

  • we can break down to drive the ever more demanding

  • construction of our technologies, our cities, and our society.

  • From food, to wood, to fossil fuels over human history

  • we've discovered ever more concentrated forms of energy

  • to unlock in order to flourish.

  • Now in the 21st century we're on the cusp of harnessing

  • the ultimate form of concentrated energy.

  • The stuff that powers the sun.

  • Hydrogen.

  • This is the Cullham Centre for Fusion Energy in Oxford

  • and at this facility they're attempting to recreate

  • a star here on earth.

  • But as you might imagine

  • creating and containing a small star

  • is not an easy process.

  • It requires many hundreds of people

  • and some extremely ingenious technology.

  • This machine is called a tokamak and it's designed to extract

  • an ancient type of highly-concentrated energy.

  • The ordered energy of hydrogen atoms.

  • These tiny packets of energy were forged in the early universe,

  • just three minutes after the moment of creation itself.

  • Now using the tokamak we can extract the concentrated energy

  • contained in these atoms by fusing them together.

  • Inside the tokamak machine two types of hydrogen gas,

  • deuterium and tritium,

  • are mixed together into a super hot state called a plasma.

  • Now, when running this plasma can reach the incredible temperature

  • of 150 million degrees!

  • Large magnets in the walls of the tokamak contain the plasma

  • and stop it touching the sides where it can cool down.

  • When it gets hot enough the two types of hydrogen atoms

  • fuse together to form helium and spit out a neutron.

  • These neutrons fly out of the plasma

  • and hit the walls of the tokamak, but they carry energy

  • and the hope is that this energy can one day be used to heat up water,

  • turn it into steam to drive a turbine and generate electricity.

  • Essentially for a brief moment inside the tokamak

  • a small doughnut-shaped star is created.

  • The problem is it's extremely difficult to sustain

  • the fusion reaction for long enough to harvest energy from it.

  • And that's what the scientists at Cullham are working to perfect.

  • It's a boundary between physics and engineering.

  • How do we hold on to this very hot thing which is the plasma?

  • And how do we optimise the way in the performance of this plasma?

  • So what we want is the particles to stay in there as long as possible

  • to maximise their chance of hitting each other.

  • We are trying to push this to the limit

  • with what we have available in this machine.

  • And whatever we can learn to understand this plasma better

  • will allow us to design a better machine in the future.

  • Although it happens several times a day... Oh, here we go.

  • The scientists here all gather round the screens.

  • OK, it's about to come on.

  • What the tokamak is doing

  • is mining the fertile ashes of the big bang.

  • Extracting concentrated energy captured at the beginning of time.

  • As hydrogen is the most abundant element in the universe,

  • if future machines can sustain fusion reactions,

  • they offer us the possibility of almost unlimited energy.

  • From a science that began as the by-product of questions

  • about steam engines,

  • thermodynamics has had a staggering impact on all our lives.

  • It has shown us why we must consume concentrated energy to stay alive

  • and has revealed to us how the universe itself is likely to end.

  • Looking at the earth at night reveals how

  • one seemingly simple idea transformed the planet.

  • Over the past 300 years, we've developed ever more ingenious ways

  • to harness the concentrated energy from the world around us.

  • But all our efforts and achievements are quite insignificant

  • when viewed from the perspective of the wider universe.

  • As far as it's concerned all we are doing is trying to preserve

  • this tiny pocket of order in a cosmos that's falling apart.

  • Although we can never escape our ultimate fate

  • the laws of physics have allowed us

  • this brief, beautiful, creative moment

  • in the great cosmic unwinding.

  • My hope is that by understanding the universe in ever greater detail

  • we can stretch this moment for many millions

  • maybe even billions of years to come.

  • The concept of information is a very strange one,

  • it's actually a very difficult idea to get your head round.

  • But in the journey to try and understand it

  • scientists would discover that

  • information is actually a fundamental part of our universe.

  • Subtitles by Red Bee Media Ltd

How did humans acquire the power to transform the planet like this?

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