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Why are we here? | 0:00:12 | 0:00:13 | |
Where do we come from? | 0:00:13 | 0:00:15 | |
These are the most enduring of questions | 0:00:15 | 0:00:19 | |
and it's an essential part of human nature | 0:00:19 | 0:00:21 | |
to want to find the answers. | 0:00:21 | 0:00:23 | |
And we can trace our ancestry back hundreds of thousands of years, | 0:00:28 | 0:00:31 | |
to the dawn of humankind, | 0:00:31 | 0:00:33 | |
but, in reality, our story extends far further back in time. | 0:00:33 | 0:00:39 | |
Our story starts with the beginning of the universe. | 0:00:39 | 0:00:42 | |
It began 13.7 billion years ago. | 0:00:47 | 0:00:51 | |
And today, it's filled with over 100 billion galaxies, | 0:00:54 | 0:00:57 | |
each containing hundreds of billions of stars. | 0:00:57 | 0:01:02 | |
In this series, I want to tell that story, | 0:01:03 | 0:01:07 | |
because, ultimately, we are part of the universe, | 0:01:07 | 0:01:10 | |
so its story is our story. | 0:01:10 | 0:01:14 | |
This film is about the stuff that makes us and where it all came from, | 0:01:17 | 0:01:22 | |
because understanding our own origins means understanding the lives of stars. | 0:01:22 | 0:01:28 | |
And how their catastrophic deaths bring new life to the universe. | 0:01:31 | 0:01:37 | |
Because every mountain, | 0:01:37 | 0:01:39 | |
every rock on this planet, every living thing, | 0:01:39 | 0:01:43 | |
every piece of you and me was forged in the furnaces of space. | 0:01:43 | 0:01:49 | |
This is Pashupatinath, | 0:02:40 | 0:02:41 | |
in the Nepalese capital city of Kathmandu | 0:02:41 | 0:02:43 | |
and Hindus come here from all over India and Nepal | 0:02:43 | 0:02:47 | |
to worship the god Shiva. That is Shiva's temple. | 0:02:47 | 0:02:51 | |
Now, Shiva is the god of destruction. | 0:02:51 | 0:02:56 | |
In the Hindu faith, everything has to be destroyed, | 0:02:56 | 0:02:59 | |
so that new things can be created | 0:02:59 | 0:03:02 | |
and that's why pilgrims come here to the banks of the Bagmati River, | 0:03:02 | 0:03:06 | |
at the foot of Shiva's temple. | 0:03:06 | 0:03:09 | |
The belief in this cycle of creation and destruction | 0:03:15 | 0:03:18 | |
lends Pashupatinath an added significance. | 0:03:18 | 0:03:21 | |
Many of these pilgrims will have come here at the end of their lives, | 0:03:26 | 0:03:30 | |
to die here and be cremated. | 0:03:30 | 0:03:33 | |
Hindus believe in reincarnation, | 0:03:36 | 0:03:38 | |
an eternal sequence of death and rebirth. | 0:03:38 | 0:03:41 | |
Cremation helps free the soul, so it's ready for the next life. | 0:03:46 | 0:03:51 | |
'They also believe that the physical elements of the body are released' | 0:03:54 | 0:03:58 | |
back to the world, so they can be recycled in the next stage of creation. | 0:03:58 | 0:04:02 | |
'It's an ancient belief that touches on a deeper truth about how the universe works.' | 0:04:09 | 0:04:16 | |
Every civilisation, | 0:04:20 | 0:04:22 | |
every religion across the world, has a creation story. | 0:04:22 | 0:04:26 | |
It tells of where we came from of how we came to be here and of what will happen when we die. | 0:04:26 | 0:04:32 | |
Well, I have a different creation story to tell and it's based entirely on physics and cosmology. | 0:04:38 | 0:04:44 | |
It can tell us what we're made of and where we came from. | 0:04:44 | 0:04:47 | |
In fact, it can tell us what everything in the world is made of and where it came from. | 0:04:47 | 0:04:52 | |
It also answers that most basic of human needs, to feel part of | 0:04:52 | 0:04:56 | |
something much bigger, because to tell this story | 0:04:56 | 0:04:59 | |
you have to understand the history of the universe. | 0:04:59 | 0:05:03 | |
And it teaches us that the path to enlightenment | 0:05:03 | 0:05:06 | |
is not an understanding of our own lives and deaths, | 0:05:06 | 0:05:10 | |
but the lives and deaths of the stars. | 0:05:10 | 0:05:13 | |
My creation story is the story of how we were made by the universe. | 0:05:24 | 0:05:30 | |
It explains how every atom in our bodies was formed, not on Earth, | 0:05:31 | 0:05:36 | |
but was created in the depths of space, | 0:05:36 | 0:05:39 | |
through the epic lifecycle of the stars. | 0:05:39 | 0:05:42 | |
And to understand that story, we will journey to the stars in all their stages of life. | 0:05:44 | 0:05:50 | |
This is where stars are born, a nebula - | 0:05:54 | 0:05:59 | |
a stellar nursery, where new stars burst into life. | 0:05:59 | 0:06:03 | |
Those stars will burn for billions of years, | 0:06:06 | 0:06:10 | |
until their voracious hunger for fuel | 0:06:10 | 0:06:12 | |
forces them to blow up, to become giants... | 0:06:12 | 0:06:15 | |
..hundreds of times the size of our sun. | 0:06:19 | 0:06:21 | |
And when they die, stars go out with the biggest bang in the universe. | 0:06:24 | 0:06:30 | |
But to understand how we came from the stars, | 0:06:39 | 0:06:43 | |
we must begin our journey much closer to home. | 0:06:43 | 0:06:46 | |
Well, this is sunrise over Nepal | 0:07:15 | 0:07:18 | |
and those are the tallest mountains in the world, the Himalayas. | 0:07:18 | 0:07:21 | |
Every one of those peaks is over 6,500 metres. | 0:07:21 | 0:07:26 | |
What a spectacular sight. | 0:07:27 | 0:07:29 | |
But it's incredible to think that, | 0:07:31 | 0:07:33 | |
just a few tens of millions of years ago, | 0:07:33 | 0:07:35 | |
those mountains were something very different. | 0:07:35 | 0:07:38 | |
'The Himalayas haven't always been mountains.' | 0:07:43 | 0:07:47 | |
We can find clues to their true origin | 0:07:50 | 0:07:53 | |
by looking at them more closely. | 0:07:53 | 0:07:55 | |
This is Himalayan limestone, | 0:07:58 | 0:08:01 | |
the rock out of which much of this magnificent mountain range is made. | 0:08:01 | 0:08:06 | |
If you look closely, you can see a kind of chalky granular structure, | 0:08:06 | 0:08:11 | |
because limestone is made primarily out of the bodies, the shells, | 0:08:11 | 0:08:15 | |
of dead sea creatures - coral and polyps - and when they die, | 0:08:15 | 0:08:20 | |
they are put under immense pressures and squashed | 0:08:20 | 0:08:23 | |
and eventually form limestone. | 0:08:23 | 0:08:25 | |
So the Himalayas were once living creatures. | 0:08:25 | 0:08:30 | |
Much of the rock in the Himalayas was formed at the bottom of an ocean and then, over millions of years, | 0:08:31 | 0:08:37 | |
it was raised up, to become these vast peaks. | 0:08:37 | 0:08:41 | |
We've even found fossils at the top of Mount Everest. | 0:08:42 | 0:08:45 | |
It's a beautiful example of the endless recycling of the earth's resources | 0:08:45 | 0:08:50 | |
that has been going on since the dawn of time - | 0:08:50 | 0:08:53 | |
and we are part of that system. | 0:08:53 | 0:08:56 | |
Every atom in my body was once part of something else, | 0:08:57 | 0:09:02 | |
so an ancient tree or a dinosaur or a rock, in fact, | 0:09:02 | 0:09:08 | |
definitely, a rock. And the reason that the rocks of the Earth | 0:09:08 | 0:09:12 | |
can become living things and then living things will return | 0:09:12 | 0:09:16 | |
to the rocks of the Earth is because everything | 0:09:16 | 0:09:20 | |
is made of the same basic ingredients. | 0:09:20 | 0:09:23 | |
Those ingredients are the chemical elements, | 0:09:26 | 0:09:29 | |
the building blocks of everything on Earth. | 0:09:29 | 0:09:32 | |
Elements like hydrogen, helium, lithium, | 0:09:36 | 0:09:41 | |
beryllium, borum, carbon, nitrogen, | 0:09:41 | 0:09:45 | |
oxygen, fluorine, neon, sodium, magnesium... | 0:09:45 | 0:09:50 | |
Everything in the world is made up of the same basic sets | 0:09:55 | 0:09:58 | |
of chemical elements, just assembled in different ways. | 0:09:58 | 0:10:01 | |
So these mountains, the Himalayas, are made of limestone - and that's calcium carbonate. | 0:10:01 | 0:10:08 | |
Now, calcium, carbon and oxygen are three of the elements that are vital for life, | 0:10:08 | 0:10:13 | |
so calcium in my teeth and bones, oxygen in the air that I breathe | 0:10:13 | 0:10:18 | |
and carbon in every organic molecule in my body. | 0:10:18 | 0:10:22 | |
Now, you're probably pretty familiar with those elements in their combined forms, | 0:10:22 | 0:10:27 | |
but you very rarely see the elements on their own. | 0:10:27 | 0:10:31 | |
There's a good reason why many of the elements are not found | 0:10:33 | 0:10:36 | |
in their raw forms in nature. They're extremely reactive. | 0:10:36 | 0:10:41 | |
This is sodium. | 0:10:42 | 0:10:43 | |
As you can see, it's a silvery metal and it's also quite reactive. | 0:10:43 | 0:10:49 | |
In fact, it's so reactive that when you drop it into water... | 0:10:49 | 0:10:52 | |
..you get a violent, | 0:10:53 | 0:10:55 | |
almost explosive, reaction, | 0:10:55 | 0:10:59 | |
which is all the more surprising when you think that, | 0:10:59 | 0:11:01 | |
when combined with chlorine, this forms sodium chloride... | 0:11:01 | 0:11:04 | |
EXPLOSION | 0:11:04 | 0:11:05 | |
..salt, which is vital for life. | 0:11:05 | 0:11:09 | |
Excellent! Ha-ha! | 0:11:10 | 0:11:14 | |
And that's why I love chemistry | 0:11:14 | 0:11:15 | |
almost as much as physics! | 0:11:15 | 0:11:17 | |
It's this reactivity that enables the elements to combine with one another to make new substances. | 0:11:19 | 0:11:25 | |
CAMERA MAN: Where's it gone? Where the hell's it gone?! | 0:11:27 | 0:11:30 | |
BRIAN LAUGHS | 0:11:30 | 0:11:31 | |
That, in turn, has allowed the Earth to develop its endless variety. | 0:11:33 | 0:11:38 | |
And that variety includes us. | 0:11:41 | 0:11:45 | |
So, to explain where we come from, | 0:11:48 | 0:11:52 | |
we must also explain where the elements come from. | 0:11:52 | 0:11:55 | |
We now know that the Earth is made of 92 chemical elements | 0:12:01 | 0:12:05 | |
and that's pretty amazing, if you think of the complexity that we see around us. | 0:12:05 | 0:12:11 | |
We also know that everything beyond Earth, everything we can see in the universe, | 0:12:11 | 0:12:15 | |
is made of those same 92 elements. | 0:12:15 | 0:12:17 | |
And notice that I didn't say, "We think" that that's what they're made of. | 0:12:17 | 0:12:21 | |
I said, "We know" that's what they're made of, because we can prove it. | 0:12:21 | 0:12:27 | |
The chemistry set we have on Earth extends far beyond the planet. | 0:12:32 | 0:12:37 | |
We have set foot on the moon and know that it's rich in helium, silver and water. | 0:12:40 | 0:12:47 | |
We have sent robot landers to our neighbouring planets and discovered that Mars | 0:12:49 | 0:12:55 | |
is rich in iron, which has combined with oxygen to form its familiar rusty-red colour. | 0:12:55 | 0:13:01 | |
And we know that Venus's thick atmosphere is full of sulphur. | 0:13:04 | 0:13:08 | |
We've sent spacecraft to the edge of the solar system | 0:13:11 | 0:13:15 | |
to discover that Neptune is rich in organic molecules, like methane. | 0:13:15 | 0:13:20 | |
But what of the rest of the universe? | 0:13:22 | 0:13:25 | |
It seems impossible that we could discover what the stars are made of, | 0:13:28 | 0:13:32 | |
because they're so far away. | 0:13:32 | 0:13:34 | |
Even the nearest star, Proxima Centauri, | 0:13:39 | 0:13:42 | |
is ten thousand times more distant than Neptune, | 0:13:42 | 0:13:46 | |
4.2 light years from Earth. | 0:13:46 | 0:13:49 | |
And the nearest galaxy, Andromeda, | 0:13:56 | 0:13:59 | |
is another 2.5m light years away. | 0:13:59 | 0:14:02 | |
Yet despite these vast distances, these alien worlds are constantly | 0:14:05 | 0:14:10 | |
sending us signals, telling us exactly what they're made of. | 0:14:10 | 0:14:15 | |
Our only contact with the distant stars is their light, | 0:14:15 | 0:14:20 | |
that has journeyed across the universe to reach us, | 0:14:20 | 0:14:23 | |
and encoded in that light is the key to understanding what the universe is made of. | 0:14:23 | 0:14:28 | |
And it's all down to a particular property of the chemical elements. | 0:14:28 | 0:14:32 | |
You see, when you heat the elements, when you burn them, then they give | 0:14:32 | 0:14:36 | |
off light and each element gives off its own unique set of colours. | 0:14:36 | 0:14:41 | |
This is strontium and it burns... | 0:14:41 | 0:14:45 | |
..with a beautiful red colour. | 0:14:47 | 0:14:49 | |
Sodium is yellow. | 0:14:54 | 0:14:56 | |
Potassium is lilac. | 0:14:59 | 0:15:01 | |
And copper is blue. | 0:15:02 | 0:15:04 | |
Each element has its own characteristic colour. | 0:15:07 | 0:15:12 | |
It's this property that tells us what the stars are made of. | 0:15:15 | 0:15:20 | |
But it's a little more complicated than simply looking at the colour of the light that each star emits. | 0:15:22 | 0:15:28 | |
You can see why, by looking at the light from our nearest star, the sun. | 0:15:30 | 0:15:35 | |
This is a spectrum of the light taken from our sun | 0:15:39 | 0:15:43 | |
and, you know, at first glance, it looks very familiar. | 0:15:43 | 0:15:46 | |
It looks like a stretched-out rainbow, | 0:15:46 | 0:15:48 | |
because that's exactly what a rainbow is. | 0:15:48 | 0:15:51 | |
It's the spectrum of the light from the sun in the sky. | 0:15:51 | 0:15:55 | |
But if you look a bit more closely, then you see that this spectrum is covered in black lines. | 0:15:55 | 0:16:00 | |
These are called absorption lines. | 0:16:00 | 0:16:03 | |
Each element within our sun not only emits light of a certain colour, | 0:16:04 | 0:16:09 | |
it also absorbs light of the same colour. | 0:16:09 | 0:16:12 | |
By looking for these black lines in the sun's light, we can simply read off a list | 0:16:12 | 0:16:18 | |
of its constituent elements, like a bar code. | 0:16:18 | 0:16:21 | |
For example, these two black lines in the yellow bit of the spectrum are sodium. | 0:16:21 | 0:16:27 | |
You can see iron. | 0:16:27 | 0:16:30 | |
Right down here you can see hydrogen. | 0:16:30 | 0:16:33 | |
So, by looking at these lines in precise detail, you can work out exactly what elements are present | 0:16:33 | 0:16:40 | |
in the sun and it turns out that that's about 70% hydrogen, 28% helium and 2% the rest. | 0:16:40 | 0:16:47 | |
And you can do this, not only for the sun, but for any of the stars | 0:16:47 | 0:16:52 | |
you can see in the sky and you can measure exactly what they're made of. | 0:16:52 | 0:16:58 | |
That star there is Polaris, the Pole Star, | 0:17:03 | 0:17:06 | |
and you can see that because all the other stars in the night sky appear to rotate around it. | 0:17:06 | 0:17:12 | |
Now it's 430 light years away. | 0:17:12 | 0:17:16 | |
But we know just by looking at the light that it has about the same heavy element abundance as our sun, | 0:17:18 | 0:17:26 | |
but it's got markedly less carbon and a lot more nitrogen. | 0:17:27 | 0:17:32 | |
And the same applies for other stars. | 0:17:37 | 0:17:40 | |
Vega, the second brightest star in the northern sky, | 0:17:41 | 0:17:45 | |
has only about a third of the metal content of our sun. | 0:17:45 | 0:17:48 | |
Whereas, other stars are metal-heavy. | 0:17:51 | 0:17:53 | |
Sirius, the dog star, contains three times as much iron as the sun. | 0:17:58 | 0:18:03 | |
And Proxima Centauri is rich in magnesium. | 0:18:05 | 0:18:09 | |
But although the quantities of the elements may vary, | 0:18:13 | 0:18:16 | |
wherever we look across space, we only ever find the same 92 elements that we find on Earth. | 0:18:16 | 0:18:23 | |
We are made of the same stuff as the stars and the galaxies. | 0:18:27 | 0:18:33 | |
But where did all this matter come from? | 0:18:40 | 0:18:43 | |
And how did it become the complex universe we see today? | 0:18:45 | 0:18:49 | |
In order to understand where we came from, we have to understand events | 0:19:12 | 0:19:17 | |
that happened in the first few seconds of the life of the universe. | 0:19:17 | 0:19:22 | |
So when the universe began, it was unimaginably hot and dense. | 0:19:22 | 0:19:27 | |
We, literally, don't have the scientific language to describe it, | 0:19:27 | 0:19:31 | |
but it was, in a very real sense, beautiful. | 0:19:31 | 0:19:35 | |
There was no structure, there was certainly no matter. | 0:19:35 | 0:19:40 | |
It was exactly the same whichever way you look at it. | 0:19:40 | 0:19:45 | |
We can get some idea of how the universe developed | 0:19:50 | 0:19:53 | |
from this state of pure symmetry by looking at the behaviour of water | 0:19:53 | 0:19:58 | |
in this remarkable landscape. | 0:19:58 | 0:20:01 | |
These are the El Tatio geysers, high in the Chilean Andes. | 0:20:03 | 0:20:08 | |
As the boiling water bubbles up through the ground to meet | 0:20:10 | 0:20:13 | |
the freezing mountain air, | 0:20:13 | 0:20:15 | |
water can be found in all three of its natural phases - | 0:20:15 | 0:20:20 | |
vapour, liquid and ice. | 0:20:20 | 0:20:22 | |
In its hottest state, water is, | 0:20:26 | 0:20:29 | |
like the early universe, an undifferentiated cloud. | 0:20:29 | 0:20:33 | |
But as it cools, it suddenly behaves very differently. | 0:20:35 | 0:20:39 | |
You see, if you look at a cloud of steam, it looks the same from every direction, | 0:20:41 | 0:20:48 | |
but as it cools down, as it lands on this plate of freezing cold glass, | 0:20:48 | 0:20:55 | |
then it immediately crystallises out. | 0:20:55 | 0:20:57 | |
It turns into solid water - ice. | 0:20:57 | 0:21:00 | |
As the ice crystals form, the symmetry of the water vapour | 0:21:04 | 0:21:07 | |
disappears from view and complex, beautiful structure emerges. | 0:21:07 | 0:21:13 | |
In the same way, we think that the universe, as it cooled, | 0:21:16 | 0:21:21 | |
went through a series of these events, where structure emerged. | 0:21:21 | 0:21:25 | |
One of the most important was about a billionth of a second after the Big Bang. | 0:21:25 | 0:21:30 | |
In that moment, an important part of the symmetry of the universe was broken. | 0:21:32 | 0:21:38 | |
Known as electroweak symmetry breaking, this was the moment when | 0:21:41 | 0:21:46 | |
subatomic particles acquired mass - substance - for the first time. | 0:21:46 | 0:21:52 | |
Amongst them, were the quarks. | 0:21:52 | 0:21:55 | |
As the universe continued to cool, those quarks joined together | 0:21:57 | 0:22:02 | |
to form larger, more complex structures, called protons and neutrons. | 0:22:02 | 0:22:07 | |
Way before the universe was a minute old, | 0:22:07 | 0:22:11 | |
the quarks had been locked away inside the protons and the neutrons | 0:22:11 | 0:22:17 | |
and they were the building blocks of all atomic nuclei, | 0:22:17 | 0:22:21 | |
the building blocks of the elements. | 0:22:21 | 0:22:23 | |
These same protons and neutrons are with us to this day. | 0:22:29 | 0:22:33 | |
They form the hearts, the nuclei, of all atoms. | 0:22:33 | 0:22:37 | |
Just a few seconds after the beginning of the universe, | 0:22:50 | 0:22:53 | |
the fundamental building blocks of everything had been created. | 0:22:53 | 0:22:58 | |
It sounds ridiculous, the fact that everything you need | 0:23:03 | 0:23:06 | |
to make up me and everything on planet Earth and, | 0:23:06 | 0:23:11 | |
in fact, every star and every galaxy in the sky was there, | 0:23:11 | 0:23:16 | |
after the first minutes in the life of the universe. | 0:23:16 | 0:23:19 | |
It's almost unbelievable, but we have extremely strong | 0:23:19 | 0:23:23 | |
experimental evidence to suggest that that is the way that it is. | 0:23:23 | 0:23:28 | |
But from that point on, it was just, in a sense, | 0:23:28 | 0:23:32 | |
a process of assembling those bits into more and more complex things. | 0:23:32 | 0:23:40 | |
That is an incredibly fascinating story in itself. | 0:23:41 | 0:23:44 | |
To tell that story, we must look deep inside the atom, to the nucleus at its centre. | 0:24:06 | 0:24:14 | |
Here, we can see how protons and neutrons are assembled, | 0:24:15 | 0:24:19 | |
to build up the 92 different elements. | 0:24:19 | 0:24:21 | |
Now, the wonderful thing about the construction of the chemical elements is that it's so simple. | 0:24:23 | 0:24:30 | |
I suppose you could call it "child's play". | 0:24:30 | 0:24:33 | |
So imagine these bubbles are my universal chemistry set... | 0:24:41 | 0:24:45 | |
..and the single bubbles could just be single protons. | 0:24:47 | 0:24:51 | |
That's the nucleus of the simplest chemical element. | 0:24:51 | 0:24:54 | |
The element with a single proton in its nucleus is hydrogen | 0:24:57 | 0:25:01 | |
and, from hydrogen, you can make all the other elements. | 0:25:01 | 0:25:05 | |
The first stage is to stick two protons together. | 0:25:08 | 0:25:12 | |
Ha-ha! Look at that! | 0:25:14 | 0:25:16 | |
That was two bubbles stuck together. | 0:25:16 | 0:25:19 | |
Now what happens when you stick two protons together is one of the protons turns into a neutron. | 0:25:19 | 0:25:24 | |
Now, that is called deuterium. | 0:25:24 | 0:25:27 | |
Deuterium is still a form of hydrogen, | 0:25:29 | 0:25:32 | |
because it has only one proton in its nucleus, and it's the number of protons that defines the element. | 0:25:32 | 0:25:39 | |
It's only when two deuterium nuclei are combined that a new element is created. | 0:25:39 | 0:25:46 | |
Take two deuteriums and fuse them together and you get a nucleus for two protons and two neutrons. | 0:25:46 | 0:25:53 | |
That's helium, the second simplest element. | 0:25:54 | 0:25:58 | |
Then, it's just a question of adding more and more protons and neutrons. | 0:26:00 | 0:26:05 | |
Well, there is an incredibly complicated nucleus. | 0:26:06 | 0:26:09 | |
That's about 12 things stuck together, so that would be probably | 0:26:09 | 0:26:13 | |
carbon 12, which is six protons and six neutrons. | 0:26:13 | 0:26:16 | |
And you can carry on building more and more complex elements... | 0:26:18 | 0:26:22 | |
..all the way up to the heaviest elements in the universe, | 0:26:24 | 0:26:29 | |
to uranium and beyond. | 0:26:29 | 0:26:31 | |
Simple, and beautiful, physics. | 0:26:31 | 0:26:35 | |
This process of building the elements is called nuclear fusion. | 0:26:43 | 0:26:48 | |
It allows the simplest of ingredients to create the infinite variety of the universe. | 0:26:48 | 0:26:54 | |
But although this bubble metaphor makes creating new elements seem simple, it is, | 0:26:56 | 0:27:02 | |
in reality, incredibly difficult to achieve. | 0:27:02 | 0:27:05 | |
So difficult that there's only one place in nature that it happens. | 0:27:10 | 0:27:15 | |
It's in stars like our sun that the elements are assembled. | 0:27:28 | 0:27:33 | |
They're the only places in the universe hot enough and dense enough to fuse atoms together. | 0:27:33 | 0:27:40 | |
Even then, only a fraction of the star reaches the extreme temperatures necessary. | 0:27:40 | 0:27:47 | |
The sun is 6,000 Celsius at its surface, not nearly hot enough to power fusion. | 0:27:47 | 0:27:54 | |
But deep below, where the temperature reaches 15m degrees, | 0:27:59 | 0:28:05 | |
the sun fuses hydrogen into helium at a furious rate. | 0:28:05 | 0:28:10 | |
Every second, it burns 600m tons of hydrogen. | 0:28:10 | 0:28:16 | |
As it does so, it releases the huge amounts of heat and light that brings our planet to life. | 0:28:20 | 0:28:28 | |
It is this process of converting one element into another that allows us to exist. | 0:28:34 | 0:28:41 | |
For all its power, the sun only converts hydrogen, | 0:28:44 | 0:28:48 | |
the simplest element, into helium, the next simplest. | 0:28:48 | 0:28:52 | |
But there are over 90 other elements present in our universe, so where did they all come from? | 0:28:52 | 0:28:57 | |
If the heavier elements are not being made in stars like the sun, then there must be somewhere else | 0:28:59 | 0:29:05 | |
in the universe where they are assembled. | 0:29:05 | 0:29:08 | |
It's important to know | 0:29:08 | 0:29:09 | |
because it's the elements beyond helium that give our world its complexity, | 0:29:09 | 0:29:14 | |
and when it comes to planet Earth and human beings, | 0:29:14 | 0:29:17 | |
there's one element that is particularly important - carbon. | 0:29:17 | 0:29:22 | |
Life is completely dependent on carbon. | 0:29:23 | 0:29:27 | |
I mean, I'm made of about a billion billion billion carbon atoms, as is | 0:29:27 | 0:29:33 | |
every human being out there, every living thing on the planet. | 0:29:33 | 0:29:38 | |
Imagine how many carbon atoms that is. | 0:29:38 | 0:29:41 | |
So where does all that carbon come from? | 0:29:41 | 0:29:43 | |
Well, it comes from the only place in the universe where elements are made - stars. | 0:29:43 | 0:29:50 | |
But in order for us to live, a star must die. | 0:29:50 | 0:29:55 | |
Stars in the prime of their lives, like our sun, are only hot enough to make helium. | 0:29:57 | 0:30:03 | |
Forming the heavier elements requires much higher temperatures. | 0:30:05 | 0:30:10 | |
Temperatures that can only be reached at the end of a star's life. | 0:30:11 | 0:30:16 | |
Looking out into space, | 0:30:21 | 0:30:22 | |
you might think that the cosmos is a constant, unchanging place. | 0:30:22 | 0:30:27 | |
That the stars will always be there. | 0:30:27 | 0:30:30 | |
But in fact, the stars are only a temporary feature in the sky, | 0:30:30 | 0:30:35 | |
and though they may burn brightly | 0:30:35 | 0:30:37 | |
for many millions or billions of years, | 0:30:37 | 0:30:41 | |
they can only live for as long as they have a supply of hydrogen to burn. | 0:30:41 | 0:30:44 | |
When a star runs out of hydrogen, it begins to die, | 0:30:47 | 0:30:51 | |
but it doesn't go quietly. | 0:30:51 | 0:30:53 | |
Rather than cooling, | 0:30:57 | 0:30:58 | |
the star becomes much hotter, until there's a sudden flash. | 0:30:58 | 0:31:02 | |
Then the star starts to expand. | 0:31:04 | 0:31:07 | |
Over tens of thousands of years, | 0:31:10 | 0:31:12 | |
it balloons to many hundreds of times its previous size. | 0:31:12 | 0:31:17 | |
But in this bloated state, | 0:31:18 | 0:31:20 | |
the star is unable to maintain its surface temperature. | 0:31:20 | 0:31:24 | |
As it cools, it takes on the characteristic colour of a dying star. | 0:31:26 | 0:31:33 | |
It has become a red giant. | 0:31:33 | 0:31:36 | |
These are pictures of a red giant star in our galaxy, a star called Betelgeuse. | 0:31:43 | 0:31:48 | |
Now, it's one of our nearest neighbours in cosmic terms. | 0:31:48 | 0:31:51 | |
It's only about 600 light years away, but it's the size that's astonishing. | 0:31:51 | 0:31:57 | |
If you were to put the sun there, then Venus would be about there | 0:31:57 | 0:32:02 | |
and the Earth about there, and Mars here, and in fact you could | 0:32:02 | 0:32:06 | |
fit everything in the solar system all the way out to Jupiter | 0:32:06 | 0:32:10 | |
inside the star. | 0:32:10 | 0:32:12 | |
Now, because it's so big, even though it is 600 light years away, | 0:32:12 | 0:32:17 | |
you can see detail on its surface, | 0:32:17 | 0:32:20 | |
so these, these are sunspots on the surface of Betelgeuse. | 0:32:20 | 0:32:24 | |
But it's not what's going on on the surface that's really interesting. | 0:32:24 | 0:32:29 | |
To understand where carbon comes from in the universe, we have to | 0:32:29 | 0:32:33 | |
understand what's going on deep in the heart of the star. | 0:32:33 | 0:32:37 | |
Imagine this old prison in Rio is a dying star like Betelgeuse. | 0:33:01 | 0:33:06 | |
Out there is the bright surface, shining off into space. | 0:33:06 | 0:33:12 | |
As I descend deeper and deeper into the prison, | 0:33:12 | 0:33:16 | |
the conditions would become hotter and hotter and denser and denser, | 0:33:16 | 0:33:21 | |
until down there in the heart in the star is the core, | 0:33:21 | 0:33:27 | |
and it's in there that all the ingredients of life are made. | 0:33:27 | 0:33:33 | |
Deep in its core, the star is fighting a futile battle against its own gravity. | 0:33:35 | 0:33:41 | |
As it desperately tries to stop itself collapsing under its own | 0:33:43 | 0:33:47 | |
weight, new elements are made in a sequence of separate stages. | 0:33:47 | 0:33:51 | |
Stage one is while there is still a supply of hydrogen to burn. | 0:33:56 | 0:34:02 | |
Whilst the star is burning hydrogen to helium in the core, vast amounts | 0:34:08 | 0:34:13 | |
of energy are released and that energy escapes, literally creating | 0:34:13 | 0:34:18 | |
an outward pressure which bounces the force of gravity and, | 0:34:18 | 0:34:23 | |
well, it holds the star up and keeps it stable. | 0:34:23 | 0:34:26 | |
But eventually, the hydrogen in the core will run out | 0:34:26 | 0:34:30 | |
and at that point the fusion reactions will stop, | 0:34:30 | 0:34:34 | |
no more energy will be released | 0:34:34 | 0:34:36 | |
and that outward pressure will disappear. | 0:34:36 | 0:34:39 | |
Now, at that point, the core will start to collapse very rapidly, | 0:34:39 | 0:34:44 | |
leaving a shell... | 0:34:44 | 0:34:46 | |
..of hydrogen and helium behind. | 0:34:49 | 0:34:53 | |
Beneath this shell, as the core collapses, | 0:34:56 | 0:35:00 | |
the temperature rises again | 0:35:00 | 0:35:03 | |
until, at 100 million degrees, | 0:35:03 | 0:35:06 | |
stage two starts and helium nuclei begin to fuse together. | 0:35:06 | 0:35:12 | |
A helium fusion does two things. | 0:35:20 | 0:35:23 | |
Firstly, more energy is released and so the collapse is halted. | 0:35:23 | 0:35:28 | |
But secondly, two more elements are produced in that process... | 0:35:28 | 0:35:33 | |
..carbon. | 0:35:35 | 0:35:37 | |
Oxygen. Two elements vital for life. | 0:35:40 | 0:35:44 | |
So this is where all the carbon in the universe comes from. | 0:35:44 | 0:35:49 | |
Every atom of carbon in my hand, | 0:35:49 | 0:35:52 | |
every atom of carbon in every living thing on the planet | 0:35:52 | 0:35:56 | |
was produced in the heart of a dying star. | 0:35:56 | 0:36:02 | |
But compared to the lifetime of the star, the creation process of carbon and oxygen is over | 0:36:03 | 0:36:10 | |
in a blink of an eye, because, in only about a million years, | 0:36:10 | 0:36:14 | |
the supply of helium in the core is used up | 0:36:14 | 0:36:18 | |
and for stars as massive as the sun, | 0:36:18 | 0:36:20 | |
that's where fusion stops, because there isn't enough | 0:36:20 | 0:36:24 | |
gravitational energy to compress the core any further and restart fusion. | 0:36:24 | 0:36:29 | |
But for massive stars like Betelgeuse, | 0:36:29 | 0:36:33 | |
the fusion process can continue. | 0:36:33 | 0:36:37 | |
When the helium runs out, | 0:36:41 | 0:36:43 | |
gravity takes over again and the collapse continues. | 0:36:43 | 0:36:48 | |
The temperature rises once more, launching stage three, | 0:36:50 | 0:36:54 | |
in which carbon fuses into magnesium, neon, | 0:36:54 | 0:36:59 | |
sodium, and aluminium. | 0:36:59 | 0:37:01 | |
And so it goes on. | 0:37:01 | 0:37:03 | |
Core collapse, followed by the next stage of fusion | 0:37:03 | 0:37:07 | |
to create more elements, each stage hotter and shorter than the last. | 0:37:07 | 0:37:14 | |
And, eventually, in a final stage that lasts only a couple of days, | 0:37:16 | 0:37:21 | |
the heart of the star is transformed into almost pure... | 0:37:21 | 0:37:27 | |
iron, whose chemical symbol is Fe, | 0:37:27 | 0:37:32 | |
and this is where the fusion process stops. | 0:37:32 | 0:37:36 | |
In its millions of years of life, | 0:37:36 | 0:37:39 | |
the star has made all the common elements, | 0:37:39 | 0:37:44 | |
the stuff that makes up 99% of the Earth. | 0:37:44 | 0:37:49 | |
The core is now a solid ball of those elements stacked on top of each other in layers. | 0:37:49 | 0:37:57 | |
On the outside, there's a shell of hydrogen. | 0:37:57 | 0:38:01 | |
Beneath it, a layer of helium. | 0:38:01 | 0:38:04 | |
Then carbon and oxygen, and all the other elements, all the way | 0:38:04 | 0:38:09 | |
down to the very heart of the star. | 0:38:09 | 0:38:12 | |
And once that has fused into solid iron, the star has only seconds left to live. | 0:38:12 | 0:38:19 | |
When a star runs out of fuel, then it can no longer release | 0:38:20 | 0:38:24 | |
energy through fusion reactions, | 0:38:24 | 0:38:27 | |
and then there's only one thing that can happen. | 0:38:27 | 0:38:30 | |
In about the same amount of time it takes this prison block to crumble, | 0:38:46 | 0:38:51 | |
the entire star falls in on itself. | 0:38:51 | 0:38:53 | |
This is the destiny that awaits most of the stars in the universe. | 0:39:01 | 0:39:06 | |
Yet even the implosion of the star only forges the first 26 elements. | 0:39:10 | 0:39:16 | |
What of the remaining elements, | 0:39:18 | 0:39:20 | |
some of which are vital for life and many of which we hold most precious? | 0:39:20 | 0:39:25 | |
These are the remote forests of northern California. | 0:39:44 | 0:39:47 | |
100 years ago, this whole area was teeming with people, all in search of one element. | 0:39:49 | 0:39:56 | |
And the reason they were here can still be found in the original Sixteen To One Mine. | 0:40:03 | 0:40:08 | |
This once stood at the centre of the California gold rush | 0:40:12 | 0:40:17 | |
and, thanks to a quirk of geology, it continues to yield its precious bounty over 100 years later. | 0:40:17 | 0:40:25 | |
You know, the unique thing about this place is that it sits right on the divide | 0:40:25 | 0:40:30 | |
between the North American plate and the Pacific plate. | 0:40:30 | 0:40:35 | |
You see a divide there between the rock and quartz, | 0:40:35 | 0:40:39 | |
then right up there you can see the top of it. | 0:40:39 | 0:40:43 | |
Now, in between the faults, this rock, the quartz, formed. | 0:40:43 | 0:40:47 | |
Then, 140 million years ago, in the Jurassic period, when the dinosaurs | 0:40:47 | 0:40:52 | |
were running around above our heads, | 0:40:52 | 0:40:55 | |
hot water welled up and flowed, and that water deposited the gold | 0:40:55 | 0:41:01 | |
through the seams of quartz, and so all the miners have to do... | 0:41:01 | 0:41:07 | |
and ALL they have to do... | 0:41:07 | 0:41:08 | |
is follow the seams of quartz, and over hundreds of years they've | 0:41:08 | 0:41:12 | |
found vast amounts of gold deposited there. | 0:41:12 | 0:41:16 | |
This is what all the fuss is about. | 0:41:31 | 0:41:33 | |
This is the gold as it comes out of the ground, | 0:41:33 | 0:41:37 | |
and it's unusually pure as gold goes. | 0:41:37 | 0:41:40 | |
This is about 85% pure gold, but it could also be found like this, | 0:41:40 | 0:41:46 | |
and this is a gold nugget that was found in a river, | 0:41:46 | 0:41:49 | |
on a river bed, and it's a heavy piece of gold. | 0:41:49 | 0:41:53 | |
It's between about one and one and a half ounces, | 0:41:53 | 0:41:56 | |
which means that at today's prices it's worth about 2,000, | 0:41:56 | 0:42:00 | |
and it's that inherent value that makes mines like this worth operating. | 0:42:00 | 0:42:07 | |
But there's something a bit odd about the value we attach to gold. | 0:42:08 | 0:42:13 | |
Throughout history, people have gone to extraordinary lengths to get their hands | 0:42:13 | 0:42:18 | |
on this most precious substance, which is strange, | 0:42:18 | 0:42:22 | |
because it isn't particularly useful for anything. | 0:42:22 | 0:42:26 | |
Most of the gold that's been extracted throughout human history | 0:42:26 | 0:42:29 | |
has ended up as jewellery, but it has got one thing going for it | 0:42:29 | 0:42:34 | |
and that's that it is incredibly rare. | 0:42:34 | 0:42:38 | |
All the gold mined from the earth in all of human history | 0:42:38 | 0:42:42 | |
would only just fill three Olympic-size swimming pools. | 0:42:42 | 0:42:46 | |
And it's that scarcity that makes gold valuable, | 0:42:48 | 0:42:53 | |
but gold is just one of many rare elements. | 0:42:53 | 0:42:56 | |
There are over 60 elements heavier than iron in the universe | 0:42:59 | 0:43:02 | |
and some are valuable, like gold, silver, platinum. | 0:43:02 | 0:43:07 | |
Some are vital for life, like copper and zinc, | 0:43:07 | 0:43:11 | |
and some are just useful, like uranium, tin and lead. | 0:43:11 | 0:43:16 | |
But across the universe, | 0:43:16 | 0:43:18 | |
there are vanishingly small amounts of those heavy elements. | 0:43:18 | 0:43:22 | |
The reason for that scarcity | 0:43:23 | 0:43:25 | |
is that creating substantial amounts of the heaviest elements requires | 0:43:25 | 0:43:30 | |
some of the rarest conditions in the universe, | 0:43:30 | 0:43:33 | |
and we need to look far into space to find them. | 0:43:33 | 0:43:37 | |
In a galaxy of 100 billion stars, these conditions will exist | 0:43:39 | 0:43:44 | |
on average for less than a minute in every century. | 0:43:44 | 0:43:48 | |
That's because they're only created in the final death throes | 0:43:54 | 0:43:59 | |
of the very largest stars... | 0:43:59 | 0:44:01 | |
..stars of at least nine times the mass of our sun. | 0:44:04 | 0:44:07 | |
Only they can reach the extreme temperatures needed | 0:44:09 | 0:44:12 | |
to create large amounts of the heavy elements. | 0:44:12 | 0:44:16 | |
Deep in the heart of the star, | 0:44:21 | 0:44:24 | |
the core finally succumbs to gravity. | 0:44:24 | 0:44:27 | |
It falls in on itself with enormous speed... | 0:44:33 | 0:44:37 | |
..and rebounds with colossal force. | 0:44:44 | 0:44:48 | |
As the blast wave collides with the outer layers of the star, | 0:44:55 | 0:44:59 | |
it generates the highest temperatures in the universe, 100 billion degrees. | 0:44:59 | 0:45:06 | |
These conditions last for just 15 seconds, but it's enough | 0:45:07 | 0:45:12 | |
to form the heaviest elements like gold. | 0:45:12 | 0:45:15 | |
It's called a supernova... | 0:45:21 | 0:45:23 | |
..the most powerful explosion in the universe. | 0:45:25 | 0:45:29 | |
It's quite a thought that something as precious to us as the gold in a wedding ring was | 0:45:36 | 0:45:43 | |
actually forged in the death of a distant star, | 0:45:43 | 0:45:46 | |
millions of light years away, billions of years ago. | 0:45:46 | 0:45:51 | |
Despite the rarity of supernovae, | 0:45:54 | 0:45:57 | |
when they do happen, they're the most dramatic events in the sky. | 0:45:57 | 0:46:03 | |
This is a picture of the Tarantula Nebula, which is a cloud of gas and dust in | 0:46:03 | 0:46:08 | |
the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way, | 0:46:08 | 0:46:13 | |
and this is what it looks like on any clear starry night of the year. | 0:46:13 | 0:46:19 | |
But on one night in 1987, the Tarantula Nebula looked like that. | 0:46:19 | 0:46:25 | |
You can see that a new bright star has appeared in the sky. | 0:46:25 | 0:46:29 | |
This is a supernova explosion, the explosive death of a massive star, | 0:46:29 | 0:46:35 | |
and they're incredibly violent cosmic events, as this picture beautifully shows. | 0:46:35 | 0:46:41 | |
This is a galaxy about 55 million light years away from Earth, | 0:46:41 | 0:46:47 | |
but this is a supernova explosion in that galaxy. | 0:46:47 | 0:46:51 | |
You can see that it's shining as brightly as the galactic core. | 0:46:51 | 0:46:55 | |
There may be a billion suns in that core, | 0:46:55 | 0:46:59 | |
and one supernova can shine as brightly as that. | 0:46:59 | 0:47:03 | |
Yet to really appreciate the scale of these explosions, we would need | 0:47:05 | 0:47:10 | |
to see one up close, to see a star die in our own galaxy, | 0:47:10 | 0:47:15 | |
the Milky Way. | 0:47:15 | 0:47:18 | |
Although on average there's one big supernova | 0:47:18 | 0:47:20 | |
in each galaxy every century, | 0:47:20 | 0:47:23 | |
there hasn't been one in the Milky Way since the birth of modern science. | 0:47:23 | 0:47:28 | |
The last was in 1604, so we're long overdue. | 0:47:28 | 0:47:32 | |
Astronomers are now searching the skies for the star that is most likely to go supernova. | 0:47:32 | 0:47:39 | |
And amongst the leading candidates there's a familiar name. | 0:47:39 | 0:47:43 | |
This is the constellation of Orion and this is Betelgeuse, | 0:47:43 | 0:47:49 | |
and we know it's extremely unstable | 0:47:49 | 0:47:53 | |
because it's dimmed by about 15% in the last ten years. | 0:47:53 | 0:47:59 | |
Now, astronomers think that this star could go supernova at any moment. | 0:47:59 | 0:48:04 | |
That could mean any time in the next million years but equally it could explode tomorrow, | 0:48:07 | 0:48:15 | |
and Betelgeuse is only 600 light years away. | 0:48:15 | 0:48:19 | |
Now, when it goes, Betelgeuse will be incredibly bright. | 0:48:21 | 0:48:26 | |
It'll be by far the brightest star in the sky. | 0:48:26 | 0:48:31 | |
It may shine as brightly as a full moon. | 0:48:31 | 0:48:34 | |
It will be almost a second sun in the daylight. | 0:48:34 | 0:48:39 | |
In this single instant, Betelgeuse will release more energy | 0:48:59 | 0:49:04 | |
than our sun will produce in its entire lifetime. | 0:49:04 | 0:49:08 | |
As the star is torn apart, it will fire out into space | 0:49:13 | 0:49:18 | |
all the elements that it created in its life and death. | 0:49:18 | 0:49:22 | |
Those elements will spread out to become a nebula, | 0:49:24 | 0:49:28 | |
a rich chemical cloud drifting through space. | 0:49:28 | 0:49:32 | |
And at the heart of the nebula will be a tiny beacon of light, | 0:49:32 | 0:49:38 | |
the remnant of a star once more than a billion and a half kilometres | 0:49:38 | 0:49:42 | |
across that has been crushed out of all recognition by gravity. | 0:49:42 | 0:49:48 | |
This is Betelgeuse, the neutron star. | 0:49:51 | 0:49:56 | |
And it's how this once mighty star will end its life. | 0:50:00 | 0:50:04 | |
Now, once Betelgeuse has gone, | 0:50:18 | 0:50:20 | |
the constellation of Orion will look very different. | 0:50:20 | 0:50:23 | |
I mean there will just be a hole in the sky | 0:50:23 | 0:50:27 | |
where that brilliant bright red star once shone. | 0:50:27 | 0:50:31 | |
But it's in the deaths of old stars that new stars are born | 0:50:31 | 0:50:35 | |
and it's very much like the cycle of death and rebirth | 0:50:35 | 0:50:40 | |
here on earth but played out on a cosmic scale, and you can see that | 0:50:40 | 0:50:44 | |
happening today in the constellation of Orion | 0:50:44 | 0:50:48 | |
because in the sword handle you can see this - the Orion nebula. | 0:50:48 | 0:50:54 | |
Now, it's nothing more than a misty patch of light in the night sky | 0:50:54 | 0:50:57 | |
to the naked eye but if you look more closely, | 0:50:57 | 0:51:01 | |
you see that there is a lot more going on. | 0:51:01 | 0:51:04 | |
The Orion nebula is one of the wonders of the universe. | 0:51:10 | 0:51:14 | |
Hidden in its clouds are bright points of light. | 0:51:20 | 0:51:23 | |
These are new stars, forming from the elements blown out by supernova explosions, | 0:51:26 | 0:51:33 | |
new stars being born from the remains of dead ones. | 0:51:37 | 0:51:42 | |
And it's from this universal process of death and rebirth that we emerged | 0:51:44 | 0:51:52 | |
because it was in a nebula just like this, five billion years ago, | 0:51:52 | 0:51:58 | |
that our sun was formed. | 0:51:58 | 0:52:00 | |
Around it, a network of planets formed. | 0:52:09 | 0:52:13 | |
Among them was the Earth. | 0:52:14 | 0:52:18 | |
Everything we find on the Earth today also originated in that nebula. | 0:52:18 | 0:52:24 | |
But that is not the end of this story of how the universe created us. | 0:52:27 | 0:52:32 | |
Because when we look deep into the nebula, | 0:52:36 | 0:52:38 | |
we don't just see individual elements. | 0:52:38 | 0:52:41 | |
We see greater complexity, the seeds of our own existence. | 0:52:41 | 0:52:46 | |
Well, this is a spectrum of the light from the Orion nebula taken | 0:52:46 | 0:52:51 | |
by the Herschel space telescope, so it really is a picture of light from interstellar space. | 0:52:51 | 0:52:58 | |
You know, I wouldn't normally show you a graph like this but this is fascinating because what it shows | 0:52:58 | 0:53:04 | |
is that that gas cloud, the Orion nebula, is not just a cloud of elements. | 0:53:04 | 0:53:10 | |
There's complex chemistry here happening in deep space because each peak on this graph | 0:53:10 | 0:53:16 | |
corresponds to a different molecule and there are some molecules present that I suppose are quite obvious. | 0:53:16 | 0:53:22 | |
There's water and there's sulphur dioxide. But there are also complex carbon compounds in here. So there's | 0:53:22 | 0:53:29 | |
methanol, there's hydrogen cyanide, there's formaldehyde, there's dimethyl ether. | 0:53:29 | 0:53:34 | |
So what we're seeing here is complex carbon chemistry happening in deep space. | 0:53:34 | 0:53:40 | |
That carbon chemistry is the beginning of the chemistry of life, | 0:53:45 | 0:53:51 | |
and there is surprising evidence that this chemistry | 0:53:51 | 0:53:54 | |
may have had a direct impact on the evolution of life on Earth. | 0:53:54 | 0:53:59 | |
That evidence comes from meteorites, | 0:54:05 | 0:54:08 | |
debris left over from the formation of the | 0:54:11 | 0:54:14 | |
solar system that occasionally collides with the earth. | 0:54:14 | 0:54:18 | |
One of the most productive places for finding meteorites | 0:54:27 | 0:54:31 | |
is the Atacama desert in the High Andes of South America. | 0:54:31 | 0:54:35 | |
This is a meteorite, a piece of rock that fell to earth from somewhere | 0:54:44 | 0:54:49 | |
out there in the solar system, and it is certainly older than any rock you can see here. | 0:54:49 | 0:54:57 | |
It's probably older than any rock you can find anywhere on Earth | 0:54:57 | 0:55:02 | |
because it formed from the primordial gas cloud, that nebula that collapsed | 0:55:02 | 0:55:07 | |
to form the sun and the planets over four and a half billion years ago. | 0:55:07 | 0:55:11 | |
So it's incredibly ancient. | 0:55:11 | 0:55:14 | |
Now this is a slice, a crosssection through a meteorite. | 0:55:14 | 0:55:19 | |
You see those little brown areas in there? | 0:55:19 | 0:55:22 | |
Well, in those brown areas we found amino acids, the building blocks of proteins, | 0:55:22 | 0:55:30 | |
which are the building blocks of me, the building blocks of life. Incredibly complex carbon compounds. | 0:55:30 | 0:55:37 | |
So this says that the complex carbon chemistry you need to send you on the path to life | 0:55:37 | 0:55:45 | |
was happening out there in space four and a half billion years ago. | 0:55:45 | 0:55:50 | |
So the first amino acids on earth, the fundamental building blocks of life, may have formed in the depths | 0:55:57 | 0:56:05 | |
of space and been delivered to the earth on meteorites. | 0:56:05 | 0:56:10 | |
When we look out into space, we are looking into our own origins. | 0:56:18 | 0:56:23 | |
Because we are truly children of the stars. | 0:56:28 | 0:56:33 | |
And written into every atom and every molecule of our bodies | 0:56:33 | 0:56:37 | |
is the entire history of the universe from the Big Bang to the present day. | 0:56:37 | 0:56:43 | |
Our story is the story of the universe | 0:56:48 | 0:56:51 | |
and every piece of everyone, of everything you love, | 0:56:51 | 0:56:55 | |
of everything you hate, of the thing you hold most precious, | 0:56:55 | 0:57:00 | |
was assembled by the forces of nature | 0:57:00 | 0:57:03 | |
in the first few minutes of the life of the universe, | 0:57:03 | 0:57:06 | |
transformed in the hearts of stars or created in their fiery deaths. | 0:57:06 | 0:57:13 | |
And when you die, those pieces will be returned to the universe | 0:57:13 | 0:57:19 | |
in the endless cycle of death and rebirth. | 0:57:19 | 0:57:23 | |
What a wonderful thing it is to be a part of that universe! | 0:57:23 | 0:57:28 | |
And what a story. | 0:57:28 | 0:57:29 | |
What a majestic story. | 0:57:29 | 0:57:32 | |
Subtitles by Red Bee Media Ltd | 0:58:00 | 0:58:04 | |
E-mail [email protected] | 0:58:04 | 0:58:08 |