Energy Order and Disorder


Energy

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

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Looking at the earth at night

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reveals to us just how successful we've been

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in harnessing and manipulating energy

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and how important it is to our existence.

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Energy is vital to us all.

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

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

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

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

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But what exactly is energy?

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And what makes it so useful to us?

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In attempting to answer these questions,

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scientists would come up with a strange set of laws

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

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

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also helps us make sense of the entire universe.

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This film is the intriguing story

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of how we discovered the rules that drive the universe.

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It is the story of how we realised

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

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To move from order to disorder.

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It's the story of how this amazing process

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has been harnessed by the universe

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to create everything that we see around us.

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Over the course of human history,

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we've come up with all sorts of different ways

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of extracting energy from our environment.

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Everything from picking fruit,

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to burning wood, to sailing boats, to waterwheels.

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But around 300 years ago, something incredible happened.

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Humans developed machines

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that were capable of processing extraordinary amounts of energy

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to carry out previously unimaginable tasks.

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

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but I'd like to begin this story

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with one of the most intriguing characters

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in the history of science.

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One of the first to attempt to understand energy.

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

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He was forever trying to understand the mechanisms

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that made the universe work.

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Leibniz like several of his great contemporaries

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was absolutely convinced that the world we see around us

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

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And if you could understand how machines worked,

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you could therefore understand how the universe

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

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So there was an extremely close relationship for Leibniz

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between theology and philosophy on the one hand

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and engineering and mechanics on the other.

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It was this relationship between philosophy and engineering

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that in 1676 would lead him to investigate

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

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What happens when objects collide?

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This is was what Leibniz

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and many of his contemporaries were grappling with.

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So when these two balls bump into each other,

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the movement of one gets transferred to the other.

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

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and this that Leibniz called the living force.

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He thought of it as a stuff,

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as a real physical substance that gets exchanged during collisions.

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Leibniz argued that the world is a living machine

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and that inside the machine,

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

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that will stay the same forever.

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

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The puzzle was to define it.

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Leibnitz would soon find a simple mathematical way

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to describe the living force.

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But he would also see something else.

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EXPLOSION

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He realised that in gunpowder, fire and steam,

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

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EXPLOSION

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If this could be harnessed,

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it could give humankind unimaginable power.

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Leibniz would soon become fascinated

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with ways of capturing the living force.

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A prolific letter writer, Leibniz struck up correspondence

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with a young French scientist called Denis Papin.

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As they corresponded, Leibniz and Papin realised

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the living force released in certain situations

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could indeed be harnessed.

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

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But how far could this idea be taken?

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Papin was in no doubt.

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

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

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

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

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

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"that one man by this means

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

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

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that Leibniz and Papin changed the world forever.

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Well, they hadn't.

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Their ideas had been profound and far reaching, yes,

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but they hadn't really moved things forward.

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For that, you need something much more tangible.

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You need innovation, industry.

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You need countless skilled workers and craftsmen

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who are going to apply these ideas,

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to experiment with them in novel and new ways.

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Well, in the century that followed Leibniz and Papin,

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this would take place in the most dramatic way imaginable.

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150 years after Leibniz and Papin's discussions,

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the living force had been harnessed in spectacular ways.

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The machines they dreamed of had become a reality.

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

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If you look at steps in civilisation,

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

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animal muscle, including our muscle, by steam power.

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And the steam power was effectively limitless

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and hugely important to doing almost unimaginable things.

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

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It would uncover the truth about what Leibniz had called

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the living force and reveal new insights

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about the workings of our universe.

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This is Crossness in south-east London.

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It's an incredible industrial cathedral,

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

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Constructed in 1854, Crossness houses four huge engines

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that once required 5,000 tonnes of coal each year

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to drive their 47-tonne beams.

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

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From the lavish ironwork -

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

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

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on a luxury ocean liner for the rich and famous.

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And yet this place was built to process sewage.

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

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steam had become

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

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that it was afforded almost religious respect.

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But for all the great success and immense power

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that engines were bestowing on their creators

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there was still a great deal of confusion and mystery

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surrounding exactly how and why they worked.

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

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"Were there limits to their power?"

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Ultimately, people wanted to know

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just what might it be possible to achieve with steam.

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The reason these questions persisted was simple almost no-one

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had understood the fundamental nature of the steam engine.

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

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

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actually were the seed of understanding

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of everything that goes on in the universe.

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As unlikely as it sounds,

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steam engines held within them the secrets of the cosmos.

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This is the Chateau de Vincennes in Paris.

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

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

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The science of heat and motion. Thermo-dynamics.

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In March 1814, during the Napoleonic wars,

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when Napoleon and his armies where fighting elsewhere,

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Paris itself came under sustained attack

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from the combined forces of Russia, Prussia and Austria.

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Citizens were deployed around key locations to protect them.

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This chateau was being defended by a group of inexperienced students

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who were forced to retreat under sustained artillery fire.

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One of them was a brilliant young scientist and soldier.

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His name was Nicolas Leonard Sadi Carnot

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and the humiliation he felt personally

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would drive him and motivate him

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to uncover a profound insight into how all engines work.

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Carnot came from a highly-respected military family.

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After the French defeat here and elsewhere around Europe,

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he became determined to reclaim French pride.

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What really bothered Carnot was the technological superiority

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that France's enemies seemed to possess.

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And Britain, in particular, had this huge advantage

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both militarily and economically

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because of its mastery of steam power.

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So Carnot vowed to really understand how steam engines work

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and use that knowledge for the benefit of France.

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He says absolutely explicitly that if you could take away

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steam engines from Britain

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then the British Empire would collapse.

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

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and he proposes to analyse,

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literally, the source of British power

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

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Living on half-pay with his brother Hippolyte

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in a small apartment in Paris,

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in 1824 Carnot wrote the now legendary

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Reflections On The Motive Power Of Fire.

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In just under 60 pages,

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he developed and abstracted the fundamental way

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in which all heat engines work.

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Carnot saw that all heat engines

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comprised of a hot source in cooler surroundings.

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Now, Carnot believed heat was some kind of substance

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

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And just like water falling from a height

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

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Carnot's crucial insight

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was to show that to make any heat engine more efficient

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

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between the heat source and cooler surroundings.

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This idea has guided engineers for 200 years.

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

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because it runs at a much hotter temperature.

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Jet engines are more efficient still

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thanks to the incredible temperatures they can run at.

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Carnot had revealed

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that heat engines weren't just a clever invention.

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They were tapping into a deeper property of nature.

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They were exploiting the flow of energy

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between hot and cold.

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

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begun a new branch of science.

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

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In 1832, a cholera epidemic spread through Paris.

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

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Now, back then, there was no real scientific understanding

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

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Carnot undaunted by the risks,

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decided to study and document the spread of the disease.

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

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He was just 36 years old.

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A lot of his precious scientific papers were burned

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to stop the spread of the contagion

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and his ideas fell into temporary obscurity.

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

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Carnot had made the first great contribution

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to the science of thermodynamics.

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

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began to grip the wider scientific community.

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Soon, it was realised these ideas could do much more

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than simply explain how heat engines worked.

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

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these ideas were applicable on a much grander scale.

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By the mid 19th century,

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scientists and engineers had worked out very precisely

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how different forms of energy relate to each other.

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

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to make a certain amount of a different kind.

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Let me give you an example.

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The amount of energy needed to heat 30ml of water

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by one degree centigrade

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is the same as the amount of energy needed

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to lift this 12.5kg weight by one metre.

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The deeper point here that people realised

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

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

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

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

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It just changes from one form to another.

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19th Century scientists realised this meant the total energy

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of the entire universe is actually fixed.

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Amazingly, there's a set amount of energy

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that just changes into many different forms.

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

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it's just changed from heat into mechanical work.

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

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

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In fact, why does it do it at all?

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

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And it would form the basis what would become known

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as the second law of thermodynamics.

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Rudolf Clausius was a brilliant German physics student

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from Pomerania

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who studied in Berlin

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and at a ridiculously young age became a very brilliant professor

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in Berlin and then in Zurich

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at the new technology university set up there in Switzerland.

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

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the first, coherent, full-blown, mathematical analysis

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of how thermodynamics works.

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Clausius realised that not only was there

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a fixed amount of energy in the universe

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

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Put simply, energy in the form of heat

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always moved in one particular direction.

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This insight of his is

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

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As Clausius put it,

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

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This is a very intuitive idea.

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

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

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

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

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

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very fundamentally into the workings of the entire universe.

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Of course, objects can get hotter

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

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Left alone, energy seems to always go from being concentrated

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to being dispersed.

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One of my favourite statements in science was made

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by the biochemist called Albert St George who said that,

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

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

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And he, Rudolf Clausius, looked at the everyday world

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and saw what everyone else had seen,

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

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It always goes the other way.

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

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He actually sat down and thought about it.

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Clausius brought together all these ideas about how energy

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is transferred and put them into mathematical context.

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It could be summarised by this equation.

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

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This letter S.

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

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

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entropy always increases.

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

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As hot things cool, their entropy increases.

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It appeared to Clausius that in any isolated system

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this process would be irreversible.

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Clausius was so confident about his mathematics

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that he figured out that this irreversible process

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was going on out there in the wider cosmos.

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He speculated that the entropy of the entire universe

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had to be increasing toward a maximum

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and there was nothing we could do to avoid this.

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This idea became known as the second law of thermodynamics

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

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more universal than anything that Clausius could have imagined.

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The second law of thermodynamics seemed to say that all things

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

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

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that was happening everywhere.

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A process of spreading out and dispersing.

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A process of increasing entropy.

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

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as a cup of tea.

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The wonderful thing about the Victorian scientists

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is that they could make these great leaps

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

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actually could be transferred... could be extrapolated,

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could be enlarged to encompass the whole universe.

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Despite the successes of thermodynamics,

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in the middle of the 19th century,

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there was great debate and confusion about the subject.

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What exactly was this strange thing called entropy

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and why was it always increasing?

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Answering this question would take an incredible intellectual leap

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but it would end up revealing the truth about energy

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and the many forms of order and disorder

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we see in the universe around us.

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Many scientists would tackle the mysterious concept of entropy.

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

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He'd show what entropy really was

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and why, over time, it always must increase.

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His name was Ludwig Boltzmann

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and he was one science's true revolutionaries.

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Boltzmann had been born in Vienna in 1844.

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It was a world of scientific and cultural certainty.

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But Boltzmann took little notice

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of the entrenched beliefs of his contemporaries.

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To him, the physical world

0:29:570:29:59

was something best explored with an open mind.

0:29:590:30:03

Boltzmann wasn't your stereotypical scientist.

0:30:050:30:09

In fact, he had the kind of temperament

0:30:090:30:12

most people might associate with great artists.

0:30:120:30:16

He was ruthlessly logical and analytical, yes,

0:30:160:30:19

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

0:30:190:30:24

followed by terrible depressions

0:30:240:30:27

which would leave him completely unable to think clearly.

0:30:270:30:30

He had terrible

0:30:360:30:39

mental crises and breakdowns

0:30:390:30:42

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

0:30:420:30:48

and yet these were also accompanied

0:30:480:30:50

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

0:30:500:30:55

Outside of mathematics, Boltzmann was passionate about music

0:30:560:31:00

and was captivated by the grand and dramatic operas of Wagner

0:31:000:31:06

and the raw emotion of Beethoven.

0:31:060:31:08

He was a brilliant pianist

0:31:100:31:12

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

0:31:120:31:17

just as he could lose himself in deep mathematical theories.

0:31:170:31:21

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

0:31:210:31:24

Boltzmann was a scientist guided by his emotions and instinct

0:31:290:31:33

and also by his belief in the ability of mathematics

0:31:330:31:37

to unlock the secrets of nature.

0:31:370:31:39

It was these traits that would lead him to become

0:31:390:31:42

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

0:31:420:31:47

One that would describe reality at the very smallest scales.

0:31:470:31:51

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

0:31:510:31:55

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

0:31:560:32:01

began speculating that, at the smallest scales,

0:32:010:32:05

the universe might operate very differently

0:32:050:32:08

to our everyday experiences.

0:32:080:32:10

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

0:32:150:32:20

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

0:32:200:32:25

Viewed in terms of atoms

0:32:380:32:40

heat would suddenly become a much less mysterious concept.

0:32:400:32:44

Boltzmann and others saw that if an object was hot

0:32:440:32:47

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

0:32:470:32:51

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

0:32:560:33:00

But this picture of the universe

0:33:030:33:05

had one seemingly insurmountable problem.

0:33:050:33:08

How could trillions and trillions of atoms,

0:33:110:33:14

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

0:33:140:33:18

How could we come up with mathematical equations

0:33:180:33:20

to describe all of this?

0:33:200:33:22

After all, atoms are constantly bumping into each other,

0:33:220:33:26

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

0:33:260:33:30

It seemed almost an impossible problem.

0:33:300:33:33

But then Boltzmann saw there was a way.

0:33:340:33:37

Boltzmann saw more clearly than anyone

0:33:450:33:48

that for physics to explain this new strata of reality

0:33:480:33:52

it had to abandon certainty.

0:33:520:33:55

Instead of trying to understand and measure the exact movements

0:34:040:34:08

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

0:34:080:34:14

simply by using the probability that atoms would be travelling

0:34:140:34:18

at certain speeds and in certain directions.

0:34:180:34:21

Boltzmann had transported himself inside matter.

0:34:290:34:33

He had imagined a world beneath our everyday reality

0:34:360:34:39

and found a mathematics to describe it.

0:34:390:34:42

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

0:34:440:34:48

to unlock energy's deepest secret -

0:34:480:34:52

despite the widespread hostility to his theories.

0:34:520:34:55

Boltzmann's ideas were highly, highly controversial.

0:35:020:35:06

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

0:35:060:35:10

But the reason we take atoms for granted is precisely because

0:35:100:35:15

Boltzmann's mathematics married up so beautifully with experiments.

0:35:150:35:19

One of the most surprising aspects of this story is that

0:35:480:35:51

many of Boltzmann's contemporaries viewed his ideas about atoms

0:35:510:35:55

with intense hostility.

0:35:550:35:57

Today the existence of atoms,

0:36:020:36:04

the idea that all matter is composed of tiny particles,

0:36:040:36:07

is something we accept without question.

0:36:070:36:10

But back in Boltzmann's time

0:36:100:36:11

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

0:36:110:36:16

Why would they?

0:36:160:36:17

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

0:36:170:36:21

How could these particles be considered as real?

0:36:210:36:23

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

0:36:340:36:38

the great Austrian physicist Ernst Mach stood up

0:36:380:36:42

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

0:36:420:36:46

It was both cutting and dismissive.

0:36:460:36:49

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

0:36:490:36:53

like Ernst Mach, it would have been doubly hurtful.

0:36:530:36:56

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

0:37:040:37:07

They're names, labels,

0:37:070:37:09

convenient fictions, calculating devices.

0:37:090:37:13

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

0:37:130:37:16

No-one's ever seen one.

0:37:160:37:18

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

0:37:180:37:23

But Boltzmann was right.

0:37:270:37:29

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

0:37:290:37:33

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

0:37:330:37:37

and understood through the mathematics of probability.

0:37:370:37:41

The foundations and certainty of 19th century science

0:37:410:37:45

were beginning to crumble.

0:37:450:37:47

As Boltzmann stared into his brave new world of atoms

0:37:550:37:59

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

0:37:590:38:05

an explanation to one of the biggest mysteries in science.

0:38:050:38:10

Boltzmann saw atoms could reveal why the second law of thermodynamics

0:38:100:38:15

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

0:38:150:38:20

Atoms had the power to reveal what entropy really was

0:38:200:38:24

and why it must always increase.

0:38:240:38:28

Boltzmann understood that all objects these walls,

0:38:320:38:36

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

0:38:360:38:41

Basically, everything we see is an assembly

0:38:410:38:45

of trillions and trillions of atoms and molecules.

0:38:450:38:48

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

0:38:480:38:53

Boltzmann saw what Clausius could not.

0:38:590:39:02

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

0:39:020:39:07

Imagine a lump of hot metal.

0:39:080:39:10

The atoms inside it are jostling around.

0:39:120:39:14

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

0:39:160:39:20

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

0:39:200:39:24

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

0:39:280:39:32

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

0:39:320:39:37

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

0:39:400:39:45

with all the energy concentrated in one place,

0:39:450:39:48

to a disordered state

0:39:480:39:50

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

0:39:500:39:56

Boltzmann's brilliant mind

0:39:560:39:58

saw this whole process could be described mathematically.

0:39:580:40:02

Boltzmann's great contribution was that,

0:40:040:40:07

although we can talk in rather sort of casual terms,

0:40:070:40:12

about things getting worse, and disorder increases,

0:40:120:40:16

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

0:40:160:40:21

So he was able to derive a formula which enabled you

0:40:210:40:25

to calculate the disorder of the system.

0:40:250:40:27

This is Boltzmann's famous equation.

0:40:360:40:39

It would be his enduring contribution to science,

0:40:390:40:43

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

0:40:430:40:46

What this equation means in essence

0:40:480:40:50

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

0:40:500:40:55

than there are for them to be tidy and ordered.

0:40:550:40:58

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

0:41:010:41:07

Things will move from order to disorder.

0:41:130:41:19

It's a law that applies to everything

0:41:310:41:35

from a dropped jug to a burning star.

0:41:350:41:38

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

0:41:400:41:45

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

0:41:530:41:57

to move from order to disorder.

0:41:570:42:00

Disorder is the fate of everything.

0:42:070:42:12

Clausius had shown that something he called entropy

0:42:180:42:22

was getting bigger all the time.

0:42:220:42:26

Now Boltzmann had revealed what this really meant

0:42:270:42:31

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

0:42:310:42:36

Energy is crumbling away.

0:42:410:42:43

It's crumbling away now as we speak.

0:42:430:42:45

So the second law is all about entropy increasing.

0:42:470:42:51

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

0:42:510:42:55

Boltzmann's passionate and romantic sensibility

0:43:230:43:26

and his belief in the power mathematics

0:43:260:43:28

had led him to one of the most important discoveries

0:43:280:43:32

in the history of science.

0:43:320:43:34

But those very same intense emotions

0:43:340:43:37

had a dark and ultimately self-destructive side.

0:43:370:43:40

Throughout his life

0:43:470:43:50

Boltzmann had been prone to severe bouts of depression.

0:43:500:43:53

Sometimes these were induced by the criticisms of his theories

0:43:530:43:56

and sometimes they just happened.

0:43:560:43:58

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

0:44:000:44:03

during a particularly bad episode.

0:44:030:44:06

In September 1906, Boltzmann and his family were on holiday

0:44:170:44:21

in Duino, near Trieste in Italy.

0:44:210:44:25

While his wife and family were out at the beach,

0:44:250:44:27

Boltzmann hanged himself,

0:44:270:44:29

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

0:44:290:44:34

Perhaps the saddest aspect of Boltzmann's story

0:44:340:44:37

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

0:44:370:44:40

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

0:44:400:44:44

were finally accepted.

0:44:440:44:46

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

0:44:460:44:50

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

0:44:590:45:05

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

0:45:050:45:09

Boltzmann's equation contains within it the mortality of everything

0:45:130:45:18

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

0:45:180:45:24

The process of change and degradation is unavoidable.

0:45:330:45:38

The second law says the universe itself must one day

0:45:380:45:42

reach a point of maximum entropy, maximum disorder.

0:45:420:45:47

The universe itself must one day die.

0:45:500:45:52

If everything degrades, if everything becomes disordered

0:46:280:46:32

you might be wondering how is it that WE exist.

0:46:320:46:36

How exactly did the universe manage to create

0:46:370:46:40

the exquisite complexity and structure of life on earth?

0:46:400:46:45

Contrary to what you might think

0:46:450:46:49

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

0:46:490:46:53

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

0:46:540:46:59

It's possible to harness the natural flow

0:47:040:47:08

from order to disorder, to tap into the process

0:47:080:47:11

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

0:47:110:47:16

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

0:47:170:47:20

with their engines

0:47:200:47:21

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

0:47:210:47:25

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

0:47:250:47:31

The engine of my car, like all engines,

0:47:490:47:51

is designed to exploit the second law.

0:47:510:47:54

It starts out with something nice and ordered like this petrol

0:47:540:47:57

stuffed full of energy.

0:47:570:47:59

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

0:47:590:48:04

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

0:48:040:48:08

not to mention dumping heat and sound into the environment.

0:48:080:48:12

It's turning order to disorder.

0:48:120:48:15

What's so spectacularly clever about my car

0:48:230:48:27

is that it can harness that dissipating energy.

0:48:270:48:30

It can siphon off a small bit of it

0:48:300:48:32

and use it to run a more ordered process

0:48:320:48:34

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

0:48:340:48:39

They tap into that flow from order to disorder

0:48:390:48:43

and do something useful.

0:48:430:48:46

But it's not just cars.

0:48:510:48:53

Evolution has designed our bodies to work

0:48:530:48:55

thanks to the very same principle.

0:48:550:48:58

If I eat this chocolate bar

0:48:580:49:00

packed full of nice, ordered energy,

0:49:000:49:03

my body processes it and turns it into more disordered energy

0:49:030:49:07

but powers itself off the proceeds.

0:49:070:49:10

Both cars and humans power themselves by tapping into

0:49:160:49:21

the great cosmic flow from order to disorder.

0:49:210:49:24

Although overall the world is falling apart in disorder

0:49:280:49:34

it is doing it in a seriously interesting way.

0:49:340:49:37

It's like a waterfall that is rushing down,

0:49:380:49:43

but the waterfall throws up a spray of structure

0:49:430:49:48

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

0:49:480:49:55

So you can see that the unwinding of the universe,

0:49:550:49:59

this collapse into disorder, can in fact be constructive.

0:49:590:50:03

Steam engines,

0:50:100:50:11

power stations,

0:50:110:50:14

life on earth -

0:50:140:50:17

all of these things harness the cosmic flow

0:50:170:50:20

from order to disorder.

0:50:200:50:22

The reason the earth now looks the way it does

0:50:320:50:35

is because we've learnt to harness the disintegrating energy

0:50:350:50:39

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

0:50:390:50:44

But as humankind has evolved,

0:50:470:50:50

we've had to find new pieces of concentrated energy

0:50:500:50:54

we can break down to drive the ever more demanding

0:50:540:50:58

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

0:50:580:51:02

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

0:51:050:51:10

we've discovered ever more concentrated forms of energy

0:51:100:51:13

to unlock in order to flourish.

0:51:130:51:16

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

0:51:280:51:32

the ultimate form of concentrated energy.

0:51:320:51:35

The stuff that powers the sun.

0:51:350:51:38

Hydrogen.

0:51:390:51:41

This is the Cullham Centre for Fusion Energy in Oxford

0:51:540:51:58

and at this facility they're attempting to recreate

0:51:580:52:03

a star here on earth.

0:52:030:52:06

But as you might imagine

0:52:060:52:07

creating and containing a small star

0:52:070:52:10

is not an easy process.

0:52:100:52:12

It requires many hundreds of people

0:52:170:52:20

and some extremely ingenious technology.

0:52:200:52:23

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

0:52:240:52:29

an ancient type of highly-concentrated energy.

0:52:290:52:32

The ordered energy of hydrogen atoms.

0:52:340:52:37

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

0:52:380:52:44

just three minutes after the moment of creation itself.

0:52:440:52:48

Now using the tokamak we can extract the concentrated energy

0:52:520:52:58

contained in these atoms by fusing them together.

0:52:580:53:01

Inside the tokamak machine two types of hydrogen gas,

0:53:060:53:11

deuterium and tritium,

0:53:110:53:13

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

0:53:130:53:18

Now, when running this plasma can reach the incredible temperature

0:53:180:53:22

of 150 million degrees!

0:53:220:53:25

Large magnets in the walls of the tokamak contain the plasma

0:53:250:53:28

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

0:53:280:53:32

When it gets hot enough the two types of hydrogen atoms

0:53:320:53:36

fuse together to form helium and spit out a neutron.

0:53:360:53:41

These neutrons fly out of the plasma

0:53:410:53:43

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

0:53:430:53:46

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

0:53:460:53:51

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

0:53:510:53:55

Essentially for a brief moment inside the tokamak

0:53:560:54:00

a small doughnut-shaped star is created.

0:54:000:54:04

The problem is it's extremely difficult to sustain

0:54:160:54:19

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

0:54:190:54:24

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

0:54:240:54:28

It's a boundary between physics and engineering.

0:54:290:54:32

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

0:54:320:54:37

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

0:54:370:54:42

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

0:54:420:54:46

to maximise their chance of hitting each other.

0:54:460:54:49

We are trying to push this to the limit

0:54:490:54:53

with what we have available in this machine.

0:54:530:54:56

And whatever we can learn to understand this plasma better

0:54:560:54:59

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

0:54:590:55:03

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

0:55:030:55:07

The scientists here all gather round the screens.

0:55:070:55:10

OK, it's about to come on.

0:55:100:55:13

What the tokamak is doing

0:55:470:55:49

is mining the fertile ashes of the big bang.

0:55:490:55:54

Extracting concentrated energy captured at the beginning of time.

0:55:540:55:58

As hydrogen is the most abundant element in the universe,

0:56:000:56:04

if future machines can sustain fusion reactions,

0:56:040:56:08

they offer us the possibility of almost unlimited energy.

0:56:080:56:12

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

0:56:220:56:26

about steam engines,

0:56:260:56:28

thermodynamics has had a staggering impact on all our lives.

0:56:280:56:32

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

0:56:340:56:39

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

0:56:390:56:45

Looking at the earth at night reveals how

0:56:480:56:51

one seemingly simple idea transformed the planet.

0:56:510:56:55

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

0:57:140:57:19

to harness the concentrated energy from the world around us.

0:57:190:57:23

But all our efforts and achievements are quite insignificant

0:57:230:57:27

when viewed from the perspective of the wider universe.

0:57:270:57:31

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

0:57:310:57:34

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

0:57:340:57:40

Although we can never escape our ultimate fate

0:57:490:57:52

the laws of physics have allowed us

0:57:520:57:55

this brief, beautiful, creative moment

0:57:550:57:59

in the great cosmic unwinding.

0:57:590:58:02

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

0:58:020:58:07

we can stretch this moment for many millions

0:58:070:58:11

maybe even billions of years to come.

0:58:110:58:14

The concept of information is a very strange one,

0:58:270:58:30

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

0:58:300:58:34

But in the journey to try and understand it

0:58:340:58:37

scientists would discover that

0:58:370:58:40

information is actually a fundamental part of our universe.

0:58:400:58:44

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