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How did humans acquire the power to transform the planet like this? | 0:00:07 | 0:00:13 | |
Looking at the earth at night | 0:00:14 | 0:00:16 | |
reveals to us just how successful we've been | 0:00:16 | 0:00:18 | |
in harnessing and manipulating energy | 0:00:18 | 0:00:21 | |
and how important it is to our existence. | 0:00:21 | 0:00:24 | |
Energy is vital to us all. | 0:00:34 | 0:00:36 | |
We use it to build the structures that surround and protect us. | 0:00:36 | 0:00:40 | |
We use it to power our transport and light our homes. | 0:00:40 | 0:00:44 | |
And even more crucially, energy is essential for life itself. | 0:00:44 | 0:00:48 | |
Without the energy we get from the food we eat, we'd die. | 0:00:48 | 0:00:52 | |
But what exactly is energy? | 0:00:52 | 0:00:54 | |
And what makes it so useful to us? | 0:00:54 | 0:00:57 | |
In attempting to answer these questions, | 0:01:02 | 0:01:04 | |
scientists would come up with a strange set of laws | 0:01:04 | 0:01:07 | |
that would link together everything, from engines, to humans, to stars. | 0:01:07 | 0:01:12 | |
It turns out that energy, so crucial to our daily lives | 0:01:12 | 0:01:17 | |
also helps us make sense of the entire universe. | 0:01:17 | 0:01:22 | |
This film is the intriguing story | 0:01:26 | 0:01:29 | |
of how we discovered the rules that drive the universe. | 0:01:29 | 0:01:34 | |
It is the story of how we realised | 0:01:39 | 0:01:42 | |
that all forms of energy are destined to degrade and fall apart. | 0:01:42 | 0:01:49 | |
To move from order to disorder. | 0:01:53 | 0:01:57 | |
It's the story of how this amazing process | 0:02:00 | 0:02:04 | |
has been harnessed by the universe | 0:02:04 | 0:02:06 | |
to create everything that we see around us. | 0:02:06 | 0:02:09 | |
Over the course of human history, | 0:02:47 | 0:02:49 | |
we've come up with all sorts of different ways | 0:02:49 | 0:02:52 | |
of extracting energy from our environment. | 0:02:52 | 0:02:55 | |
Everything from picking fruit, | 0:02:55 | 0:02:57 | |
to burning wood, to sailing boats, to waterwheels. | 0:02:57 | 0:03:02 | |
But around 300 years ago, something incredible happened. | 0:03:02 | 0:03:06 | |
Humans developed machines | 0:03:06 | 0:03:08 | |
that were capable of processing extraordinary amounts of energy | 0:03:08 | 0:03:12 | |
to carry out previously unimaginable tasks. | 0:03:12 | 0:03:15 | |
This happened thanks to many people and for many different reasons, | 0:03:15 | 0:03:19 | |
but I'd like to begin this story | 0:03:19 | 0:03:21 | |
with one of the most intriguing characters | 0:03:21 | 0:03:23 | |
in the history of science. | 0:03:23 | 0:03:25 | |
One of the first to attempt to understand energy. | 0:03:25 | 0:03:29 | |
Gottfried Leibniz was a diplomat, scientist, philosopher and genius. | 0:03:45 | 0:03:51 | |
He was forever trying to understand the mechanisms | 0:03:51 | 0:03:54 | |
that made the universe work. | 0:03:54 | 0:03:56 | |
Leibniz like several of his great contemporaries | 0:03:58 | 0:04:01 | |
was absolutely convinced that the world we see around us | 0:04:01 | 0:04:04 | |
is a vast machine designed by a powerful and wise person. | 0:04:04 | 0:04:10 | |
And if you could understand how machines worked, | 0:04:10 | 0:04:15 | |
you could therefore understand how the universe | 0:04:15 | 0:04:18 | |
and the principles that had been used to make the universe worked as well. | 0:04:18 | 0:04:23 | |
So there was an extremely close relationship for Leibniz | 0:04:23 | 0:04:30 | |
between theology and philosophy on the one hand | 0:04:30 | 0:04:33 | |
and engineering and mechanics on the other. | 0:04:33 | 0:04:35 | |
It was this relationship between philosophy and engineering | 0:04:39 | 0:04:41 | |
that in 1676 would lead him to investigate | 0:04:41 | 0:04:46 | |
what at first sight seemed to be a very simple question. | 0:04:46 | 0:04:50 | |
What happens when objects collide? | 0:04:57 | 0:04:59 | |
This is was what Leibniz | 0:04:59 | 0:05:01 | |
and many of his contemporaries were grappling with. | 0:05:01 | 0:05:04 | |
So when these two balls bump into each other, | 0:05:04 | 0:05:07 | |
the movement of one gets transferred to the other. | 0:05:07 | 0:05:11 | |
It's as though something's been passed between them | 0:05:12 | 0:05:14 | |
and this that Leibniz called the living force. | 0:05:14 | 0:05:18 | |
He thought of it as a stuff, | 0:05:18 | 0:05:20 | |
as a real physical substance that gets exchanged during collisions. | 0:05:20 | 0:05:26 | |
Leibniz argued that the world is a living machine | 0:05:34 | 0:05:39 | |
and that inside the machine, | 0:05:39 | 0:05:42 | |
there is a quantity of living force put there by God at the Creation | 0:05:42 | 0:05:47 | |
that will stay the same forever. | 0:05:47 | 0:05:49 | |
So the amount of living force in the world will be conserved. | 0:05:49 | 0:05:54 | |
The puzzle was to define it. | 0:05:54 | 0:05:56 | |
Leibnitz would soon find a simple mathematical way | 0:06:01 | 0:06:05 | |
to describe the living force. | 0:06:05 | 0:06:08 | |
But he would also see something else. | 0:06:08 | 0:06:10 | |
EXPLOSION | 0:06:10 | 0:06:12 | |
He realised that in gunpowder, fire and steam, | 0:06:12 | 0:06:17 | |
his living force was being released in violent and powerful ways. | 0:06:17 | 0:06:22 | |
EXPLOSION | 0:06:25 | 0:06:26 | |
If this could be harnessed, | 0:06:35 | 0:06:38 | |
it could give humankind unimaginable power. | 0:06:38 | 0:06:41 | |
Leibniz would soon become fascinated | 0:06:51 | 0:06:53 | |
with ways of capturing the living force. | 0:06:53 | 0:06:56 | |
A prolific letter writer, Leibniz struck up correspondence | 0:07:03 | 0:07:07 | |
with a young French scientist called Denis Papin. | 0:07:07 | 0:07:10 | |
As they corresponded, Leibniz and Papin realised | 0:07:15 | 0:07:18 | |
the living force released in certain situations | 0:07:18 | 0:07:22 | |
could indeed be harnessed. | 0:07:22 | 0:07:24 | |
Heat could be converted in to some form of useful action. | 0:07:25 | 0:07:30 | |
But how far could this idea be taken? | 0:07:36 | 0:07:40 | |
Papin was in no doubt. | 0:07:40 | 0:07:42 | |
This is an extract from his letter to Leibniz... | 0:07:42 | 0:07:45 | |
"I can assure you that the more I go forward, | 0:07:48 | 0:07:50 | |
"the more I find reason to think highly of this invention, | 0:07:50 | 0:07:53 | |
"which in theory, may augment the powers of man to infinity. | 0:07:53 | 0:07:59 | |
"But in practice, I believe I can say without exaggeration, | 0:07:59 | 0:08:02 | |
"that one man by this means | 0:08:02 | 0:08:04 | |
"will be able to do as much as 100 others can do without it." | 0:08:04 | 0:08:08 | |
Now, you might expect me at this point to tell you | 0:08:11 | 0:08:14 | |
that Leibniz and Papin changed the world forever. | 0:08:14 | 0:08:18 | |
Well, they hadn't. | 0:08:18 | 0:08:19 | |
Their ideas had been profound and far reaching, yes, | 0:08:19 | 0:08:22 | |
but they hadn't really moved things forward. | 0:08:22 | 0:08:25 | |
For that, you need something much more tangible. | 0:08:25 | 0:08:29 | |
You need innovation, industry. | 0:08:29 | 0:08:31 | |
You need countless skilled workers and craftsmen | 0:08:31 | 0:08:34 | |
who are going to apply these ideas, | 0:08:34 | 0:08:37 | |
to experiment with them in novel and new ways. | 0:08:37 | 0:08:40 | |
Well, in the century that followed Leibniz and Papin, | 0:08:40 | 0:08:43 | |
this would take place in the most dramatic way imaginable. | 0:08:43 | 0:08:47 | |
150 years after Leibniz and Papin's discussions, | 0:08:56 | 0:09:01 | |
the living force had been harnessed in spectacular ways. | 0:09:01 | 0:09:05 | |
The machines they dreamed of had become a reality. | 0:09:06 | 0:09:09 | |
Steam engines were now the cutting edge of 19th century technology. | 0:09:09 | 0:09:15 | |
If you look at steps in civilisation, | 0:09:24 | 0:09:26 | |
then one great step was the steam engine, because it replaced muscle, | 0:09:26 | 0:09:32 | |
animal muscle, including our muscle, by steam power. | 0:09:32 | 0:09:35 | |
And the steam power was effectively limitless | 0:09:35 | 0:09:38 | |
and hugely important to doing almost unimaginable things. | 0:09:38 | 0:09:43 | |
But steam technology would do more than just transform human society. | 0:09:51 | 0:09:56 | |
It would uncover the truth about what Leibniz had called | 0:09:56 | 0:09:59 | |
the living force and reveal new insights | 0:09:59 | 0:10:03 | |
about the workings of our universe. | 0:10:03 | 0:10:05 | |
This is Crossness in south-east London. | 0:10:10 | 0:10:14 | |
It's an incredible industrial cathedral, | 0:10:14 | 0:10:18 | |
home to some of the most impressive Victorian steam engines ever built. | 0:10:18 | 0:10:23 | |
Constructed in 1854, Crossness houses four huge engines | 0:10:32 | 0:10:39 | |
that once required 5,000 tonnes of coal each year | 0:10:39 | 0:10:44 | |
to drive their 47-tonne beams. | 0:10:44 | 0:10:46 | |
Everything about this place seems to have been built to impress. | 0:11:02 | 0:11:07 | |
From the lavish ironwork - | 0:11:07 | 0:11:09 | |
the grand pillars like something out of a Greek or Roman temple. | 0:11:09 | 0:11:14 | |
It's the kind of effort you'd think would be lavished | 0:11:14 | 0:11:16 | |
on a luxury ocean liner for the rich and famous. | 0:11:16 | 0:11:20 | |
And yet this place was built to process sewage. | 0:11:20 | 0:11:24 | |
Although only a few workers and engineers would see inside it, | 0:11:24 | 0:11:29 | |
steam had become | 0:11:29 | 0:11:30 | |
such a vital part of Britain's power and economic prosperity | 0:11:30 | 0:11:35 | |
that it was afforded almost religious respect. | 0:11:35 | 0:11:39 | |
But for all the great success and immense power | 0:11:53 | 0:11:56 | |
that engines were bestowing on their creators | 0:11:56 | 0:11:59 | |
there was still a great deal of confusion and mystery | 0:11:59 | 0:12:03 | |
surrounding exactly how and why they worked. | 0:12:03 | 0:12:06 | |
In particular questions like, "How efficient could they be made?" | 0:12:06 | 0:12:11 | |
"Were there limits to their power?" | 0:12:11 | 0:12:13 | |
Ultimately, people wanted to know | 0:12:13 | 0:12:15 | |
just what might it be possible to achieve with steam. | 0:12:15 | 0:12:19 | |
The reason these questions persisted was simple almost no-one | 0:12:30 | 0:12:34 | |
had understood the fundamental nature of the steam engine. | 0:12:34 | 0:12:38 | |
Very few were aware of the cosmic principle which underpinned it. | 0:12:38 | 0:12:42 | |
These great lumbering machines we think of as the early steam engines | 0:12:46 | 0:12:51 | |
actually were the seed of understanding | 0:12:51 | 0:12:54 | |
of everything that goes on in the universe. | 0:12:54 | 0:12:57 | |
As unlikely as it sounds, | 0:13:01 | 0:13:04 | |
steam engines held within them the secrets of the cosmos. | 0:13:04 | 0:13:09 | |
This is the Chateau de Vincennes in Paris. | 0:13:33 | 0:13:36 | |
Events here would motivate one man's journey to uncover the cosmic truth | 0:13:36 | 0:13:41 | |
about the steam engine, and help to create a new science. | 0:13:41 | 0:13:46 | |
The science of heat and motion. Thermo-dynamics. | 0:13:46 | 0:13:50 | |
In March 1814, during the Napoleonic wars, | 0:14:05 | 0:14:08 | |
when Napoleon and his armies where fighting elsewhere, | 0:14:08 | 0:14:12 | |
Paris itself came under sustained attack | 0:14:12 | 0:14:15 | |
from the combined forces of Russia, Prussia and Austria. | 0:14:15 | 0:14:19 | |
Citizens were deployed around key locations to protect them. | 0:14:19 | 0:14:23 | |
This chateau was being defended by a group of inexperienced students | 0:14:23 | 0:14:29 | |
who were forced to retreat under sustained artillery fire. | 0:14:29 | 0:14:33 | |
One of them was a brilliant young scientist and soldier. | 0:14:33 | 0:14:37 | |
His name was Nicolas Leonard Sadi Carnot | 0:14:37 | 0:14:41 | |
and the humiliation he felt personally | 0:14:41 | 0:14:44 | |
would drive him and motivate him | 0:14:44 | 0:14:47 | |
to uncover a profound insight into how all engines work. | 0:14:47 | 0:14:52 | |
Carnot came from a highly-respected military family. | 0:14:56 | 0:14:59 | |
After the French defeat here and elsewhere around Europe, | 0:14:59 | 0:15:03 | |
he became determined to reclaim French pride. | 0:15:03 | 0:15:07 | |
What really bothered Carnot was the technological superiority | 0:15:13 | 0:15:17 | |
that France's enemies seemed to possess. | 0:15:17 | 0:15:19 | |
And Britain, in particular, had this huge advantage | 0:15:19 | 0:15:24 | |
both militarily and economically | 0:15:24 | 0:15:27 | |
because of its mastery of steam power. | 0:15:27 | 0:15:30 | |
So Carnot vowed to really understand how steam engines work | 0:15:30 | 0:15:36 | |
and use that knowledge for the benefit of France. | 0:15:36 | 0:15:40 | |
He says absolutely explicitly that if you could take away | 0:15:42 | 0:15:46 | |
steam engines from Britain | 0:15:46 | 0:15:48 | |
then the British Empire would collapse. | 0:15:48 | 0:15:51 | |
And he's writing in the wake of French military defeat | 0:15:51 | 0:15:55 | |
and he proposes to analyse, | 0:15:55 | 0:15:58 | |
literally, the source of British power | 0:15:58 | 0:16:02 | |
by analysing the way in which fire and heat engines work. | 0:16:02 | 0:16:07 | |
Living on half-pay with his brother Hippolyte | 0:16:10 | 0:16:12 | |
in a small apartment in Paris, | 0:16:12 | 0:16:15 | |
in 1824 Carnot wrote the now legendary | 0:16:15 | 0:16:18 | |
Reflections On The Motive Power Of Fire. | 0:16:18 | 0:16:22 | |
In just under 60 pages, | 0:16:22 | 0:16:24 | |
he developed and abstracted the fundamental way | 0:16:24 | 0:16:28 | |
in which all heat engines work. | 0:16:28 | 0:16:30 | |
Carnot saw that all heat engines | 0:16:30 | 0:16:32 | |
comprised of a hot source in cooler surroundings. | 0:16:32 | 0:16:37 | |
Now, Carnot believed heat was some kind of substance | 0:16:38 | 0:16:42 | |
that would flow like water from the hot to the cool. | 0:16:42 | 0:16:47 | |
And just like water falling from a height | 0:16:47 | 0:16:50 | |
the flow of heat could be tapped to do useful work. | 0:16:50 | 0:16:53 | |
Carnot's crucial insight | 0:16:58 | 0:17:00 | |
was to show that to make any heat engine more efficient | 0:17:00 | 0:17:03 | |
all you had to do was to increase the difference in temperature | 0:17:03 | 0:17:08 | |
between the heat source and cooler surroundings. | 0:17:08 | 0:17:11 | |
This idea has guided engineers for 200 years. | 0:17:15 | 0:17:20 | |
Ultimately, a car engine is more efficient than a steam engine | 0:17:22 | 0:17:25 | |
because it runs at a much hotter temperature. | 0:17:25 | 0:17:29 | |
Jet engines are more efficient still | 0:17:29 | 0:17:32 | |
thanks to the incredible temperatures they can run at. | 0:17:32 | 0:17:35 | |
Carnot had revealed | 0:17:38 | 0:17:40 | |
that heat engines weren't just a clever invention. | 0:17:40 | 0:17:44 | |
They were tapping into a deeper property of nature. | 0:17:44 | 0:17:48 | |
They were exploiting the flow of energy | 0:17:49 | 0:17:53 | |
between hot and cold. | 0:17:53 | 0:17:55 | |
Carnot had glimpsed the true nature of heat engines and, in the process, | 0:18:00 | 0:18:07 | |
begun a new branch of science. | 0:18:07 | 0:18:09 | |
But he would never see the impact his idea would have on the world. | 0:18:09 | 0:18:14 | |
In 1832, a cholera epidemic spread through Paris. | 0:18:16 | 0:18:20 | |
It was so severe, it would kill almost 19,000 people. | 0:18:20 | 0:18:25 | |
Now, back then, there was no real scientific understanding | 0:18:25 | 0:18:28 | |
of how the disease spread, so it must have been terrifying. | 0:18:28 | 0:18:31 | |
Carnot undaunted by the risks, | 0:18:31 | 0:18:34 | |
decided to study and document the spread of the disease. | 0:18:34 | 0:18:38 | |
But, unfortunately, he contracted it himself and was dead a day later. | 0:18:38 | 0:18:44 | |
He was just 36 years old. | 0:18:44 | 0:18:46 | |
A lot of his precious scientific papers were burned | 0:18:46 | 0:18:50 | |
to stop the spread of the contagion | 0:18:50 | 0:18:52 | |
and his ideas fell into temporary obscurity. | 0:18:52 | 0:18:55 | |
It seems the world wasn't quite ready for Carnot. | 0:18:55 | 0:19:00 | |
Carnot had made the first great contribution | 0:19:04 | 0:19:07 | |
to the science of thermodynamics. | 0:19:07 | 0:19:11 | |
But as the 19th century progressed the study of heat, motion and energy | 0:19:11 | 0:19:16 | |
began to grip the wider scientific community. | 0:19:16 | 0:19:19 | |
Soon, it was realised these ideas could do much more | 0:19:19 | 0:19:24 | |
than simply explain how heat engines worked. | 0:19:24 | 0:19:26 | |
Just as Leibniz had suspected with his notion of living force, | 0:19:26 | 0:19:31 | |
these ideas were applicable on a much grander scale. | 0:19:31 | 0:19:36 | |
By the mid 19th century, | 0:19:49 | 0:19:51 | |
scientists and engineers had worked out very precisely | 0:19:51 | 0:19:54 | |
how different forms of energy relate to each other. | 0:19:54 | 0:19:58 | |
They measured how much of a particular kind of energy is needed | 0:19:58 | 0:20:02 | |
to make a certain amount of a different kind. | 0:20:02 | 0:20:06 | |
Let me give you an example. | 0:20:06 | 0:20:08 | |
The amount of energy needed to heat 30ml of water | 0:20:08 | 0:20:14 | |
by one degree centigrade | 0:20:14 | 0:20:16 | |
is the same as the amount of energy needed | 0:20:16 | 0:20:19 | |
to lift this 12.5kg weight by one metre. | 0:20:19 | 0:20:24 | |
The deeper point here that people realised | 0:20:26 | 0:20:29 | |
was that although mechanical work and heat may seem very different, | 0:20:29 | 0:20:34 | |
they are, in fact, both facets of the same thing - energy. | 0:20:34 | 0:20:40 | |
This idea would come to be known as the first law of thermodynamics. | 0:20:42 | 0:20:48 | |
The first law reveals that energy is never created or destroyed. | 0:20:48 | 0:20:53 | |
It just changes from one form to another. | 0:20:53 | 0:20:57 | |
19th Century scientists realised this meant the total energy | 0:20:59 | 0:21:03 | |
of the entire universe is actually fixed. | 0:21:03 | 0:21:07 | |
Amazingly, there's a set amount of energy | 0:21:07 | 0:21:11 | |
that just changes into many different forms. | 0:21:11 | 0:21:15 | |
So, in a steam engine, energy isn't created - | 0:21:15 | 0:21:20 | |
it's just changed from heat into mechanical work. | 0:21:20 | 0:21:24 | |
But impressive though the first law is, it begged an enormous question - | 0:21:31 | 0:21:36 | |
what exactly is going on when one form of energy changes into another? | 0:21:36 | 0:21:42 | |
In fact, why does it do it at all? | 0:21:42 | 0:21:44 | |
The answer would, in part, be found by German scientist Rudolf Clausius. | 0:21:51 | 0:21:58 | |
And it would form the basis what would become known | 0:21:58 | 0:22:01 | |
as the second law of thermodynamics. | 0:22:01 | 0:22:03 | |
Rudolf Clausius was a brilliant German physics student | 0:22:09 | 0:22:14 | |
from Pomerania | 0:22:14 | 0:22:16 | |
who studied in Berlin | 0:22:16 | 0:22:18 | |
and at a ridiculously young age became a very brilliant professor | 0:22:18 | 0:22:22 | |
in Berlin and then in Zurich | 0:22:22 | 0:22:26 | |
at the new technology university set up there in Switzerland. | 0:22:26 | 0:22:30 | |
In the 1850s and 60s, Clausius offered what was really | 0:22:30 | 0:22:36 | |
the first, coherent, full-blown, mathematical analysis | 0:22:36 | 0:22:41 | |
of how thermodynamics works. | 0:22:41 | 0:22:44 | |
Clausius realised that not only was there | 0:22:47 | 0:22:50 | |
a fixed amount of energy in the universe | 0:22:50 | 0:22:52 | |
but that the energy seemed to be following a very strict rule. | 0:22:52 | 0:22:57 | |
Put simply, energy in the form of heat | 0:22:59 | 0:23:02 | |
always moved in one particular direction. | 0:23:02 | 0:23:05 | |
This insight of his is | 0:23:09 | 0:23:10 | |
in fact one of the most important ideas in the whole of science. | 0:23:10 | 0:23:15 | |
As Clausius put it, | 0:23:15 | 0:23:17 | |
"Heat cannot of itself pass from a colder to a hotter body". | 0:23:17 | 0:23:22 | |
This is a very intuitive idea. | 0:23:22 | 0:23:24 | |
If left alone, this hot mug of tea will always cool down. | 0:23:24 | 0:23:29 | |
What this means is that heat will pass from the hot mug | 0:23:29 | 0:23:33 | |
say to my hand and then again from my hand to my chest. | 0:23:33 | 0:23:39 | |
This might seem completely obvious but it was a crucial insight. | 0:23:46 | 0:23:51 | |
The flow of heat was a one-way process that seemed to be built | 0:23:53 | 0:23:58 | |
very fundamentally into the workings of the entire universe. | 0:23:58 | 0:24:03 | |
Of course, objects can get hotter | 0:24:07 | 0:24:10 | |
but you always need to do something to them to make this happen. | 0:24:10 | 0:24:14 | |
Left alone, energy seems to always go from being concentrated | 0:24:17 | 0:24:22 | |
to being dispersed. | 0:24:22 | 0:24:24 | |
One of my favourite statements in science was made | 0:24:34 | 0:24:38 | |
by the biochemist called Albert St George who said that, | 0:24:38 | 0:24:41 | |
"Science is all about seeing what everyone else has seen, | 0:24:41 | 0:24:45 | |
"but thinking what no-one else has thought." | 0:24:45 | 0:24:48 | |
And he, Rudolf Clausius, looked at the everyday world | 0:24:48 | 0:24:55 | |
and saw what everyone else had seen, | 0:24:55 | 0:24:57 | |
that heat does not flow spontaneously from a cold body to a hot body. | 0:24:57 | 0:25:03 | |
It always goes the other way. | 0:25:03 | 0:25:05 | |
But he didn't just say, "Ah, I see that." | 0:25:05 | 0:25:09 | |
He actually sat down and thought about it. | 0:25:09 | 0:25:11 | |
Clausius brought together all these ideas about how energy | 0:25:19 | 0:25:22 | |
is transferred and put them into mathematical context. | 0:25:22 | 0:25:26 | |
It could be summarised by this equation. | 0:25:26 | 0:25:29 | |
Now, what Clausius did was introduce a new quantity he called entropy. | 0:25:47 | 0:25:52 | |
This letter S. | 0:25:52 | 0:25:54 | |
Basically, what it's saying in the context of this equation | 0:25:54 | 0:25:58 | |
is that as heat is transferred from hotter to colder bodies, | 0:25:58 | 0:26:02 | |
entropy always increases. | 0:26:02 | 0:26:05 | |
Entropy seemed to be a measure of how heat dissipates or spreads out. | 0:26:11 | 0:26:17 | |
As hot things cool, their entropy increases. | 0:26:17 | 0:26:22 | |
It appeared to Clausius that in any isolated system | 0:26:22 | 0:26:26 | |
this process would be irreversible. | 0:26:26 | 0:26:29 | |
Clausius was so confident about his mathematics | 0:26:39 | 0:26:42 | |
that he figured out that this irreversible process | 0:26:42 | 0:26:46 | |
was going on out there in the wider cosmos. | 0:26:46 | 0:26:49 | |
He speculated that the entropy of the entire universe | 0:26:49 | 0:26:53 | |
had to be increasing toward a maximum | 0:26:53 | 0:26:55 | |
and there was nothing we could do to avoid this. | 0:26:55 | 0:26:59 | |
This idea became known as the second law of thermodynamics | 0:26:59 | 0:27:04 | |
and it turned out to be stranger, and more beautiful, | 0:27:04 | 0:27:07 | |
more universal than anything that Clausius could have imagined. | 0:27:07 | 0:27:12 | |
The second law of thermodynamics seemed to say that all things | 0:27:21 | 0:27:26 | |
that gave off heat were, in some way, connected together. | 0:27:26 | 0:27:30 | |
All things that gave off heat were part of an irreversible process | 0:27:33 | 0:27:38 | |
that was happening everywhere. | 0:27:38 | 0:27:40 | |
A process of spreading out and dispersing. | 0:27:41 | 0:27:45 | |
A process of increasing entropy. | 0:27:46 | 0:27:49 | |
It seemed that, somehow, the universe shared the same fate | 0:27:52 | 0:27:57 | |
as a cup of tea. | 0:27:57 | 0:27:59 | |
The wonderful thing about the Victorian scientists | 0:28:01 | 0:28:05 | |
is that they could make these great leaps | 0:28:05 | 0:28:08 | |
and they could see that their study of a thermometer in a beaker | 0:28:08 | 0:28:13 | |
actually could be transferred... could be extrapolated, | 0:28:13 | 0:28:17 | |
could be enlarged to encompass the whole universe. | 0:28:17 | 0:28:20 | |
Despite the successes of thermodynamics, | 0:28:39 | 0:28:42 | |
in the middle of the 19th century, | 0:28:42 | 0:28:44 | |
there was great debate and confusion about the subject. | 0:28:44 | 0:28:47 | |
What exactly was this strange thing called entropy | 0:28:47 | 0:28:52 | |
and why was it always increasing? | 0:28:52 | 0:28:53 | |
Answering this question would take an incredible intellectual leap | 0:28:55 | 0:28:59 | |
but it would end up revealing the truth about energy | 0:28:59 | 0:29:03 | |
and the many forms of order and disorder | 0:29:03 | 0:29:06 | |
we see in the universe around us. | 0:29:06 | 0:29:08 | |
Many scientists would tackle the mysterious concept of entropy. | 0:29:12 | 0:29:17 | |
But one more than any other would shed light on the truth. | 0:29:17 | 0:29:21 | |
He'd show what entropy really was | 0:29:21 | 0:29:23 | |
and why, over time, it always must increase. | 0:29:23 | 0:29:27 | |
His name was Ludwig Boltzmann | 0:29:27 | 0:29:30 | |
and he was one science's true revolutionaries. | 0:29:30 | 0:29:34 | |
Boltzmann had been born in Vienna in 1844. | 0:29:45 | 0:29:48 | |
It was a world of scientific and cultural certainty. | 0:29:48 | 0:29:53 | |
But Boltzmann took little notice | 0:29:53 | 0:29:54 | |
of the entrenched beliefs of his contemporaries. | 0:29:54 | 0:29:57 | |
To him, the physical world | 0:29:57 | 0:29:59 | |
was something best explored with an open mind. | 0:29:59 | 0:30:03 | |
Boltzmann wasn't your stereotypical scientist. | 0:30:05 | 0:30:09 | |
In fact, he had the kind of temperament | 0:30:09 | 0:30:12 | |
most people might associate with great artists. | 0:30:12 | 0:30:16 | |
He was ruthlessly logical and analytical, yes, | 0:30:16 | 0:30:19 | |
but while working, he'd go through periods of intense emotion | 0:30:19 | 0:30:24 | |
followed by terrible depressions | 0:30:24 | 0:30:27 | |
which would leave him completely unable to think clearly. | 0:30:27 | 0:30:30 | |
He had terrible | 0:30:36 | 0:30:39 | |
mental crises and breakdowns | 0:30:39 | 0:30:42 | |
in which he really thought that the world was coming apart at the seams | 0:30:42 | 0:30:48 | |
and yet these were also accompanied | 0:30:48 | 0:30:50 | |
by some of the most profound insights into the nature of our world. | 0:30:50 | 0:30:55 | |
Outside of mathematics, Boltzmann was passionate about music | 0:30:56 | 0:31:00 | |
and was captivated by the grand and dramatic operas of Wagner | 0:31:00 | 0:31:06 | |
and the raw emotion of Beethoven. | 0:31:06 | 0:31:08 | |
He was a brilliant pianist | 0:31:10 | 0:31:12 | |
and could lose himself for hours in the works of his favourite composers | 0:31:12 | 0:31:17 | |
just as he could lose himself in deep mathematical theories. | 0:31:17 | 0:31:21 | |
MUSIC: Beethoven's 5th Symphony - First Movement. | 0:31:21 | 0:31:24 | |
Boltzmann was a scientist guided by his emotions and instinct | 0:31:29 | 0:31:33 | |
and also by his belief in the ability of mathematics | 0:31:33 | 0:31:37 | |
to unlock the secrets of nature. | 0:31:37 | 0:31:39 | |
It was these traits that would lead him to become | 0:31:39 | 0:31:42 | |
one of the champions of a shocking and controversial new theory. | 0:31:42 | 0:31:47 | |
One that would describe reality at the very smallest scales. | 0:31:47 | 0:31:51 | |
Far smaller than anything we could see with the naked eye. | 0:31:51 | 0:31:55 | |
During the second half of the 19th century, a small group of scientists | 0:31:56 | 0:32:01 | |
began speculating that, at the smallest scales, | 0:32:01 | 0:32:05 | |
the universe might operate very differently | 0:32:05 | 0:32:08 | |
to our everyday experiences. | 0:32:08 | 0:32:10 | |
If you could look close enough, it seemed possible that the universe | 0:32:15 | 0:32:20 | |
might be made of tiny, hard particles, in constant motion. | 0:32:20 | 0:32:25 | |
Viewed in terms of atoms | 0:32:38 | 0:32:40 | |
heat would suddenly become a much less mysterious concept. | 0:32:40 | 0:32:44 | |
Boltzmann and others saw that if an object was hot | 0:32:44 | 0:32:47 | |
it simply meant that its atoms were moving about more rapidly. | 0:32:47 | 0:32:51 | |
Viewing the world as atoms seemed to be an immensely powerful idea. | 0:32:56 | 0:33:00 | |
But this picture of the universe | 0:33:03 | 0:33:05 | |
had one seemingly insurmountable problem. | 0:33:05 | 0:33:08 | |
How could trillions and trillions of atoms, | 0:33:11 | 0:33:14 | |
even in a tiny volume of gas, ever be studied? | 0:33:14 | 0:33:18 | |
How could we come up with mathematical equations | 0:33:18 | 0:33:20 | |
to describe all of this? | 0:33:20 | 0:33:22 | |
After all, atoms are constantly bumping into each other, | 0:33:22 | 0:33:26 | |
changing direction and speed, and there are just so many of them. | 0:33:26 | 0:33:30 | |
It seemed almost an impossible problem. | 0:33:30 | 0:33:33 | |
But then Boltzmann saw there was a way. | 0:33:34 | 0:33:37 | |
Boltzmann saw more clearly than anyone | 0:33:45 | 0:33:48 | |
that for physics to explain this new strata of reality | 0:33:48 | 0:33:52 | |
it had to abandon certainty. | 0:33:52 | 0:33:55 | |
Instead of trying to understand and measure the exact movements | 0:34:04 | 0:34:08 | |
of each individual atom, Boltzmann saw you could build working theories | 0:34:08 | 0:34:14 | |
simply by using the probability that atoms would be travelling | 0:34:14 | 0:34:18 | |
at certain speeds and in certain directions. | 0:34:18 | 0:34:21 | |
Boltzmann had transported himself inside matter. | 0:34:29 | 0:34:33 | |
He had imagined a world beneath our everyday reality | 0:34:36 | 0:34:39 | |
and found a mathematics to describe it. | 0:34:39 | 0:34:42 | |
It would be here at this scale that Boltzmann would one day manage | 0:34:44 | 0:34:48 | |
to unlock energy's deepest secret - | 0:34:48 | 0:34:52 | |
despite the widespread hostility to his theories. | 0:34:52 | 0:34:55 | |
Boltzmann's ideas were highly, highly controversial. | 0:35:02 | 0:35:06 | |
And you have to remember that today we take atoms for granted. | 0:35:06 | 0:35:10 | |
But the reason we take atoms for granted is precisely because | 0:35:10 | 0:35:15 | |
Boltzmann's mathematics married up so beautifully with experiments. | 0:35:15 | 0:35:19 | |
One of the most surprising aspects of this story is that | 0:35:48 | 0:35:51 | |
many of Boltzmann's contemporaries viewed his ideas about atoms | 0:35:51 | 0:35:55 | |
with intense hostility. | 0:35:55 | 0:35:57 | |
Today the existence of atoms, | 0:36:02 | 0:36:04 | |
the idea that all matter is composed of tiny particles, | 0:36:04 | 0:36:07 | |
is something we accept without question. | 0:36:07 | 0:36:10 | |
But back in Boltzmann's time | 0:36:10 | 0:36:11 | |
there were notable, eminent physicists who just didn't buy it. | 0:36:11 | 0:36:16 | |
Why would they? | 0:36:16 | 0:36:17 | |
No-one had ever seen an atom and probably no-one ever would. | 0:36:17 | 0:36:21 | |
How could these particles be considered as real? | 0:36:21 | 0:36:23 | |
After one of Boltzmann's lectures on atomic theory in Vienna | 0:36:34 | 0:36:38 | |
the great Austrian physicist Ernst Mach stood up | 0:36:38 | 0:36:42 | |
and said simply, "I don't believe that atoms exist!" | 0:36:42 | 0:36:46 | |
It was both cutting and dismissive. | 0:36:46 | 0:36:49 | |
And for such a comment to come from a highly regarded scientist | 0:36:49 | 0:36:53 | |
like Ernst Mach, it would have been doubly hurtful. | 0:36:53 | 0:36:56 | |
They argued that, "No, atoms don't exist." | 0:37:04 | 0:37:07 | |
They're names, labels, | 0:37:07 | 0:37:09 | |
convenient fictions, calculating devices. | 0:37:09 | 0:37:13 | |
They don't really exist. We can't observe them. | 0:37:13 | 0:37:16 | |
No-one's ever seen one. | 0:37:16 | 0:37:18 | |
And for that reason, so Boltzmann's critics said, he was a fantasist. | 0:37:18 | 0:37:23 | |
But Boltzmann was right. | 0:37:27 | 0:37:29 | |
He had peered deeper into reality than anyone else had dared, | 0:37:29 | 0:37:33 | |
and seen that the universe could be built from the atomic hypothesis | 0:37:33 | 0:37:37 | |
and understood through the mathematics of probability. | 0:37:37 | 0:37:41 | |
The foundations and certainty of 19th century science | 0:37:41 | 0:37:45 | |
were beginning to crumble. | 0:37:45 | 0:37:47 | |
As Boltzmann stared into his brave new world of atoms | 0:37:55 | 0:37:59 | |
he began to realise his new vision of the universe contained within it | 0:37:59 | 0:38:05 | |
an explanation to one of the biggest mysteries in science. | 0:38:05 | 0:38:10 | |
Boltzmann saw atoms could reveal why the second law of thermodynamics | 0:38:10 | 0:38:15 | |
was true, why nature was engaged in an irreversible process. | 0:38:15 | 0:38:20 | |
Atoms had the power to reveal what entropy really was | 0:38:20 | 0:38:24 | |
and why it must always increase. | 0:38:24 | 0:38:28 | |
Boltzmann understood that all objects these walls, | 0:38:32 | 0:38:36 | |
you, me, the air in this room, are made up of much tinier constituents. | 0:38:36 | 0:38:41 | |
Basically, everything we see is an assembly | 0:38:41 | 0:38:45 | |
of trillions and trillions of atoms and molecules. | 0:38:45 | 0:38:48 | |
And this was the key to his insight about entropy and the second law. | 0:38:48 | 0:38:53 | |
Boltzmann saw what Clausius could not. | 0:38:59 | 0:39:02 | |
The real reason why a hot object left alone will always cool down. | 0:39:02 | 0:39:07 | |
Imagine a lump of hot metal. | 0:39:08 | 0:39:10 | |
The atoms inside it are jostling around. | 0:39:12 | 0:39:14 | |
But as they jostle, the atoms at the edge of the object | 0:39:16 | 0:39:20 | |
transfer some of their energy to the atoms on the surface of the table. | 0:39:20 | 0:39:24 | |
These atoms then bump into their neighbours, and in this way, | 0:39:28 | 0:39:32 | |
the heat energy slowly and very naturally spreads out and disperses. | 0:39:32 | 0:39:37 | |
The whole system has gone from being in a special, ordered state | 0:39:40 | 0:39:45 | |
with all the energy concentrated in one place, | 0:39:45 | 0:39:48 | |
to a disordered state | 0:39:48 | 0:39:50 | |
where the same amount of energy is distributed amongst many more atoms. | 0:39:50 | 0:39:56 | |
Boltzmann's brilliant mind | 0:39:56 | 0:39:58 | |
saw this whole process could be described mathematically. | 0:39:58 | 0:40:02 | |
Boltzmann's great contribution was that, | 0:40:04 | 0:40:07 | |
although we can talk in rather sort of casual terms, | 0:40:07 | 0:40:12 | |
about things getting worse, and disorder increases, | 0:40:12 | 0:40:16 | |
the great contribution of Boltzmann is that he could put numbers to it. | 0:40:16 | 0:40:21 | |
So he was able to derive a formula which enabled you | 0:40:21 | 0:40:25 | |
to calculate the disorder of the system. | 0:40:25 | 0:40:27 | |
This is Boltzmann's famous equation. | 0:40:36 | 0:40:39 | |
It would be his enduring contribution to science, | 0:40:39 | 0:40:43 | |
so much so, it was engraved on his tombstone in Vienna. | 0:40:43 | 0:40:46 | |
What this equation means in essence | 0:40:48 | 0:40:50 | |
is there are many more ways for things to be messy and disordered | 0:40:50 | 0:40:55 | |
than there are for them to be tidy and ordered. | 0:40:55 | 0:40:58 | |
That's why, left to itself, the universe will always get messier. | 0:41:01 | 0:41:07 | |
Things will move from order to disorder. | 0:41:13 | 0:41:19 | |
It's a law that applies to everything | 0:41:31 | 0:41:35 | |
from a dropped jug to a burning star. | 0:41:35 | 0:41:38 | |
A hot cup of tea to the products that we consume every day. | 0:41:40 | 0:41:45 | |
All of this is an expression of the universe's tendency | 0:41:53 | 0:41:57 | |
to move from order to disorder. | 0:41:57 | 0:42:00 | |
Disorder is the fate of everything. | 0:42:07 | 0:42:12 | |
Clausius had shown that something he called entropy | 0:42:18 | 0:42:22 | |
was getting bigger all the time. | 0:42:22 | 0:42:26 | |
Now Boltzmann had revealed what this really meant | 0:42:27 | 0:42:31 | |
entropy was in fact a measure of the disorder of things. | 0:42:31 | 0:42:36 | |
Energy is crumbling away. | 0:42:41 | 0:42:43 | |
It's crumbling away now as we speak. | 0:42:43 | 0:42:45 | |
So the second law is all about entropy increasing. | 0:42:47 | 0:42:51 | |
It's just a technical way of saying things get worse. | 0:42:51 | 0:42:55 | |
Boltzmann's passionate and romantic sensibility | 0:43:23 | 0:43:26 | |
and his belief in the power mathematics | 0:43:26 | 0:43:28 | |
had led him to one of the most important discoveries | 0:43:28 | 0:43:32 | |
in the history of science. | 0:43:32 | 0:43:34 | |
But those very same intense emotions | 0:43:34 | 0:43:37 | |
had a dark and ultimately self-destructive side. | 0:43:37 | 0:43:40 | |
Throughout his life | 0:43:47 | 0:43:50 | |
Boltzmann had been prone to severe bouts of depression. | 0:43:50 | 0:43:53 | |
Sometimes these were induced by the criticisms of his theories | 0:43:53 | 0:43:56 | |
and sometimes they just happened. | 0:43:56 | 0:43:58 | |
In 1906, he was forced to take a break from his studies in Vienna | 0:44:00 | 0:44:03 | |
during a particularly bad episode. | 0:44:03 | 0:44:06 | |
In September 1906, Boltzmann and his family were on holiday | 0:44:17 | 0:44:21 | |
in Duino, near Trieste in Italy. | 0:44:21 | 0:44:25 | |
While his wife and family were out at the beach, | 0:44:25 | 0:44:27 | |
Boltzmann hanged himself, | 0:44:27 | 0:44:29 | |
bringing his short time in our universe to an abrupt end. | 0:44:29 | 0:44:34 | |
Perhaps the saddest aspect of Boltzmann's story | 0:44:34 | 0:44:37 | |
is that, within a few short years of his death, | 0:44:37 | 0:44:40 | |
his ideas that had been attacked and ridiculed during his life, | 0:44:40 | 0:44:44 | |
were finally accepted. | 0:44:44 | 0:44:46 | |
What's more, they became the new scientific orthodoxy. | 0:44:46 | 0:44:50 | |
In the end there is no escaping entropy it is the ultimate move | 0:44:59 | 0:45:05 | |
from order, to decay and disorder, that rules us all. | 0:45:05 | 0:45:09 | |
Boltzmann's equation contains within it the mortality of everything | 0:45:13 | 0:45:18 | |
from a china jug to a human life to the universe itself. | 0:45:18 | 0:45:24 | |
The process of change and degradation is unavoidable. | 0:45:33 | 0:45:38 | |
The second law says the universe itself must one day | 0:45:38 | 0:45:42 | |
reach a point of maximum entropy, maximum disorder. | 0:45:42 | 0:45:47 | |
The universe itself must one day die. | 0:45:50 | 0:45:52 | |
If everything degrades, if everything becomes disordered | 0:46:28 | 0:46:32 | |
you might be wondering how is it that WE exist. | 0:46:32 | 0:46:36 | |
How exactly did the universe manage to create | 0:46:37 | 0:46:40 | |
the exquisite complexity and structure of life on earth? | 0:46:40 | 0:46:45 | |
Contrary to what you might think | 0:46:45 | 0:46:49 | |
it's precisely because of the second law that all this exists. | 0:46:49 | 0:46:53 | |
The great disordering of the cosmos gives rise to its complexity. | 0:46:54 | 0:46:59 | |
It's possible to harness the natural flow | 0:47:04 | 0:47:08 | |
from order to disorder, to tap into the process | 0:47:08 | 0:47:11 | |
and generate something new, to create new order and new structure. | 0:47:11 | 0:47:16 | |
It's what the early steam pioneers had unwittingly hit upon | 0:47:17 | 0:47:20 | |
with their engines | 0:47:20 | 0:47:21 | |
and it's what makes everything we deem special in our world - | 0:47:21 | 0:47:25 | |
from this car, to buildings, to works of art, even to life itself. | 0:47:25 | 0:47:31 | |
The engine of my car, like all engines, | 0:47:49 | 0:47:51 | |
is designed to exploit the second law. | 0:47:51 | 0:47:54 | |
It starts out with something nice and ordered like this petrol | 0:47:54 | 0:47:57 | |
stuffed full of energy. | 0:47:57 | 0:47:59 | |
But when it is ignited in the engine it turns this compact liquid | 0:47:59 | 0:48:04 | |
into a mixture of gases 2,000 times greater in volume - | 0:48:04 | 0:48:08 | |
not to mention dumping heat and sound into the environment. | 0:48:08 | 0:48:12 | |
It's turning order to disorder. | 0:48:12 | 0:48:15 | |
What's so spectacularly clever about my car | 0:48:23 | 0:48:27 | |
is that it can harness that dissipating energy. | 0:48:27 | 0:48:30 | |
It can siphon off a small bit of it | 0:48:30 | 0:48:32 | |
and use it to run a more ordered process | 0:48:32 | 0:48:34 | |
like driving the pistons which turn the wheels. That's what engines do. | 0:48:34 | 0:48:39 | |
They tap into that flow from order to disorder | 0:48:39 | 0:48:43 | |
and do something useful. | 0:48:43 | 0:48:46 | |
But it's not just cars. | 0:48:51 | 0:48:53 | |
Evolution has designed our bodies to work | 0:48:53 | 0:48:55 | |
thanks to the very same principle. | 0:48:55 | 0:48:58 | |
If I eat this chocolate bar | 0:48:58 | 0:49:00 | |
packed full of nice, ordered energy, | 0:49:00 | 0:49:03 | |
my body processes it and turns it into more disordered energy | 0:49:03 | 0:49:07 | |
but powers itself off the proceeds. | 0:49:07 | 0:49:10 | |
Both cars and humans power themselves by tapping into | 0:49:16 | 0:49:21 | |
the great cosmic flow from order to disorder. | 0:49:21 | 0:49:24 | |
Although overall the world is falling apart in disorder | 0:49:28 | 0:49:34 | |
it is doing it in a seriously interesting way. | 0:49:34 | 0:49:37 | |
It's like a waterfall that is rushing down, | 0:49:38 | 0:49:43 | |
but the waterfall throws up a spray of structure | 0:49:43 | 0:49:48 | |
and that spray of structure might be you or me or a daffodil or whatever. | 0:49:48 | 0:49:55 | |
So you can see that the unwinding of the universe, | 0:49:55 | 0:49:59 | |
this collapse into disorder, can in fact be constructive. | 0:49:59 | 0:50:03 | |
Steam engines, | 0:50:10 | 0:50:11 | |
power stations, | 0:50:11 | 0:50:14 | |
life on earth - | 0:50:14 | 0:50:17 | |
all of these things harness the cosmic flow | 0:50:17 | 0:50:20 | |
from order to disorder. | 0:50:20 | 0:50:22 | |
The reason the earth now looks the way it does | 0:50:32 | 0:50:35 | |
is because we've learnt to harness the disintegrating energy | 0:50:35 | 0:50:39 | |
of the universe to maintain and improve our small pocket of order. | 0:50:39 | 0:50:44 | |
But as humankind has evolved, | 0:50:47 | 0:50:50 | |
we've had to find new pieces of concentrated energy | 0:50:50 | 0:50:54 | |
we can break down to drive the ever more demanding | 0:50:54 | 0:50:58 | |
construction of our technologies, our cities, and our society. | 0:50:58 | 0:51:02 | |
From food, to wood, to fossil fuels over human history | 0:51:05 | 0:51:10 | |
we've discovered ever more concentrated forms of energy | 0:51:10 | 0:51:13 | |
to unlock in order to flourish. | 0:51:13 | 0:51:16 | |
Now in the 21st century we're on the cusp of harnessing | 0:51:28 | 0:51:32 | |
the ultimate form of concentrated energy. | 0:51:32 | 0:51:35 | |
The stuff that powers the sun. | 0:51:35 | 0:51:38 | |
Hydrogen. | 0:51:39 | 0:51:41 | |
This is the Cullham Centre for Fusion Energy in Oxford | 0:51:54 | 0:51:58 | |
and at this facility they're attempting to recreate | 0:51:58 | 0:52:03 | |
a star here on earth. | 0:52:03 | 0:52:06 | |
But as you might imagine | 0:52:06 | 0:52:07 | |
creating and containing a small star | 0:52:07 | 0:52:10 | |
is not an easy process. | 0:52:10 | 0:52:12 | |
It requires many hundreds of people | 0:52:17 | 0:52:20 | |
and some extremely ingenious technology. | 0:52:20 | 0:52:23 | |
This machine is called a tokamak and it's designed to extract | 0:52:24 | 0:52:29 | |
an ancient type of highly-concentrated energy. | 0:52:29 | 0:52:32 | |
The ordered energy of hydrogen atoms. | 0:52:34 | 0:52:37 | |
These tiny packets of energy were forged in the early universe, | 0:52:38 | 0:52:44 | |
just three minutes after the moment of creation itself. | 0:52:44 | 0:52:48 | |
Now using the tokamak we can extract the concentrated energy | 0:52:52 | 0:52:58 | |
contained in these atoms by fusing them together. | 0:52:58 | 0:53:01 | |
Inside the tokamak machine two types of hydrogen gas, | 0:53:06 | 0:53:11 | |
deuterium and tritium, | 0:53:11 | 0:53:13 | |
are mixed together into a super hot state called a plasma. | 0:53:13 | 0:53:18 | |
Now, when running this plasma can reach the incredible temperature | 0:53:18 | 0:53:22 | |
of 150 million degrees! | 0:53:22 | 0:53:25 | |
Large magnets in the walls of the tokamak contain the plasma | 0:53:25 | 0:53:28 | |
and stop it touching the sides where it can cool down. | 0:53:28 | 0:53:32 | |
When it gets hot enough the two types of hydrogen atoms | 0:53:32 | 0:53:36 | |
fuse together to form helium and spit out a neutron. | 0:53:36 | 0:53:41 | |
These neutrons fly out of the plasma | 0:53:41 | 0:53:43 | |
and hit the walls of the tokamak, but they carry energy | 0:53:43 | 0:53:46 | |
and the hope is that this energy can one day be used to heat up water, | 0:53:46 | 0:53:51 | |
turn it into steam to drive a turbine and generate electricity. | 0:53:51 | 0:53:55 | |
Essentially for a brief moment inside the tokamak | 0:53:56 | 0:54:00 | |
a small doughnut-shaped star is created. | 0:54:00 | 0:54:04 | |
The problem is it's extremely difficult to sustain | 0:54:16 | 0:54:19 | |
the fusion reaction for long enough to harvest energy from it. | 0:54:19 | 0:54:24 | |
And that's what the scientists at Cullham are working to perfect. | 0:54:24 | 0:54:28 | |
It's a boundary between physics and engineering. | 0:54:29 | 0:54:32 | |
How do we hold on to this very hot thing which is the plasma? | 0:54:32 | 0:54:37 | |
And how do we optimise the way in the performance of this plasma? | 0:54:37 | 0:54:42 | |
So what we want is the particles to stay in there as long as possible | 0:54:42 | 0:54:46 | |
to maximise their chance of hitting each other. | 0:54:46 | 0:54:49 | |
We are trying to push this to the limit | 0:54:49 | 0:54:53 | |
with what we have available in this machine. | 0:54:53 | 0:54:56 | |
And whatever we can learn to understand this plasma better | 0:54:56 | 0:54:59 | |
will allow us to design a better machine in the future. | 0:54:59 | 0:55:03 | |
Although it happens several times a day... Oh, here we go. | 0:55:03 | 0:55:07 | |
The scientists here all gather round the screens. | 0:55:07 | 0:55:10 | |
OK, it's about to come on. | 0:55:10 | 0:55:13 | |
What the tokamak is doing | 0:55:47 | 0:55:49 | |
is mining the fertile ashes of the big bang. | 0:55:49 | 0:55:54 | |
Extracting concentrated energy captured at the beginning of time. | 0:55:54 | 0:55:58 | |
As hydrogen is the most abundant element in the universe, | 0:56:00 | 0:56:04 | |
if future machines can sustain fusion reactions, | 0:56:04 | 0:56:08 | |
they offer us the possibility of almost unlimited energy. | 0:56:08 | 0:56:12 | |
From a science that began as the by-product of questions | 0:56:22 | 0:56:26 | |
about steam engines, | 0:56:26 | 0:56:28 | |
thermodynamics has had a staggering impact on all our lives. | 0:56:28 | 0:56:32 | |
It has shown us why we must consume concentrated energy to stay alive | 0:56:34 | 0:56:39 | |
and has revealed to us how the universe itself is likely to end. | 0:56:39 | 0:56:45 | |
Looking at the earth at night reveals how | 0:56:48 | 0:56:51 | |
one seemingly simple idea transformed the planet. | 0:56:51 | 0:56:55 | |
Over the past 300 years, we've developed ever more ingenious ways | 0:57:14 | 0:57:19 | |
to harness the concentrated energy from the world around us. | 0:57:19 | 0:57:23 | |
But all our efforts and achievements are quite insignificant | 0:57:23 | 0:57:27 | |
when viewed from the perspective of the wider universe. | 0:57:27 | 0:57:31 | |
As far as it's concerned all we are doing is trying to preserve | 0:57:31 | 0:57:34 | |
this tiny pocket of order in a cosmos that's falling apart. | 0:57:34 | 0:57:40 | |
Although we can never escape our ultimate fate | 0:57:49 | 0:57:52 | |
the laws of physics have allowed us | 0:57:52 | 0:57:55 | |
this brief, beautiful, creative moment | 0:57:55 | 0:57:59 | |
in the great cosmic unwinding. | 0:57:59 | 0:58:02 | |
My hope is that by understanding the universe in ever greater detail | 0:58:02 | 0:58:07 | |
we can stretch this moment for many millions | 0:58:07 | 0:58:11 | |
maybe even billions of years to come. | 0:58:11 | 0:58:14 | |
The concept of information is a very strange one, | 0:58:27 | 0:58:30 | |
it's actually a very difficult idea to get your head round. | 0:58:30 | 0:58:34 | |
But in the journey to try and understand it | 0:58:34 | 0:58:37 | |
scientists would discover that | 0:58:37 | 0:58:40 | |
information is actually a fundamental part of our universe. | 0:58:40 | 0:58:44 | |
Subtitles by Red Bee Media Ltd | 0:59:12 | 0:59:14 |