Original subtitles

PROFESSOR BRIAN COX: Why are we here? Where do we come from?

These are the most enduring of questions.

And it's an essential part of human nature to want to find the answers.

Now, we can trace our ancestry back hundreds of thousands of years

to the dawn of humankind.

But in reality, our story extends far further back in time.

Our story starts with the beginning of the universe.

It began 13.7 billion years ago.

And today, it's filled with over a hundred billion galaxies,

each containing hundreds of billions of stars.

In this series, I want to tell that story.

Because ultimately, we are part of the universe.

So its story is our story.

This film is about the stuff that makes us

and where it all came from.

Because understanding our own origins

means understanding the lives of stars...

...and how their catastrophic deaths bring new life to the universe.

Because every mountain, every rock on this planet,

every living thing, every piece of you and me

was forged in the furnaces of space.

(BIRDS CHIRPING)

(CHILDREN LAUGHING)

This is Pashupatinath in the Nepalese capital city of Kathmandu.

And Hindus come here from all over India and Nepal

to worship the god Shiva.

In fact, that is Shiva's temple.

Now, Shiva is the god of destruction.

In the Hindu faith, everything has to be destroyed

so that new things can be created.

And that's why pilgrims come here to the banks of the Bagmati River

at the foot of Shiva's temple.

The belief in this cycle of creation and destruction

lends Pashupatinath an added significance.

Many of these pilgrims will have come here at the end of their lives,

to die here and be cremated.

Hindus believe in reincarnation, an eternal sequence of death and rebirth.

Cremation helps free the soul, so it's ready for the next life.

They also believe that the physical elements of the body

are released back to the world

so they can be recycled in the next stage of creation.

It's an ancient belief that touches on a deeper truth

about how the universe works.

Every civilization, every religion across the world has a creation story.

It tells of where we came from, of how we came to be here

and of what will happen when we die.

Well, I have a different creation story to tell,

and it's based entirely on physics and cosmology.

Now, it can tell us what we're made of and where we came from.

In fact, it can tell us what everything in the world

is made of and where it came from.

It also answers that most basic of human needs,

to feel part of something much bigger.

Because to tell this story,

you have to understand the history of the universe.

And it teaches us that the path to enlightenment

is not an understanding of our own lives and deaths,

but the lives and deaths of the stars.

My creation story is the story of how we were made by the universe.

It explains how every atom in our bodies was formed not on Earth,

but was created in the depths of space,

through the epic life cycle of the stars.

And to understand that story,

we will journey to the stars in all their stages of life.

This is where stars are born, a nebula,

a stellar nursery, where new stars burst into life.

Those stars will burn for billions of years,

until their voracious hunger for fuel forces them to blow up,

to become giants

hundreds of times the size of our sun.

And when they die, stars go out with the biggest bang in the universe.

But to understand how we came from the stars,

we must begin our journey much closer to home.

Well, this is sunrise over Nepal

and those are the tallest mountains in the world, the Himalayas.

I mean, every one of those peaks is over six and a half thousand metres.

What a spectacular sight.

But it's incredible to think that just a few tens of millions of years ago,

those mountains were something very different.

The Himalayas haven't always been mountains.

We can find clues to their true origin by looking at them more closely.

This is Himalayan limestone,

the rock out of which much of this magnificent mountain range is made.

Now, if you look closely, you can see a kind of chalky, granular structure.

Because limestone is made primarily out of the bodies,

the shells of dead sea creatures, of coral and polyps.

And when they die, they are put under immense pressures and squashed

and eventually form limestone.

So the Himalayas were once living creatures.

Much of the rock in the Himalayas was formed at the bottom of an ocean.

And then over millions of years, it was raised up to become these vast peaks.

We've even found fossils at the top of Mount Everest.

It's a beautiful example of the endless recycling of the Earth's resources

that has been going on since the dawn of time.

And we are part of that system.

Every atom in my body was once part of something else.

So an ancient tree or a dinosaur or a rock,

in fact, definitely a rock.

And the reason that the rocks of the Earth can become living things

and then living things will return to the rocks of the Earth

is because everything is made of the same basic ingredients.

Those ingredients are the chemical elements,

the building blocks of everything on Earth.

Elements like hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen,

oxygen, fluorine, neon, sodium, magnesium,

aluminium, silicon, phosphorus...

Everything in the world is made up of the same basic set of chemical elements,

just assembled in different ways.

So these mountains, the Himalayas, are made of limestone.

And that's calcium carbonate.

Now, calcium, carbon and oxygen

are three of the elements that are vital for life.

The calcium in my teeth and bones, oxygen in the air that I breathe

and carbon in every organic molecule in my body.

Now, you're probably pretty familiar

with those elements in their combined forms,

but you very rarely see the elements on their own.

There's a good reason why many of the elements

are not found in their raw forms in nature.

They are extremely reactive.

This is sodium.

As you can see, it's a silvery metal. It's also quite reactive.

In fact, it's so reactive that when you drop it into water,

you get a violent, almost explosive, reaction.

Which is all the more surprising

when you think that when combined with chlorine,

this forms sodium chloride,

salt, which is vital for life.

Excellent.

(LAUGHING)

And that's why I love chemistry almost as much as physics.

It's this reactivity that enables the elements

to combine with one another to make new substances.

MAN 1 : It's gone. MAN 2: Where the hell's it gone?

(COX LAUGHING)

That, in turn, has allowed the Earth to develop its endless variety.

And that variety includes us.

So to explain where we come from,

we must also explain where the elements come from.

We now know that the Earth is made of 92 chemical elements.

And that's pretty amazing, if you think of the complexity that we see around us.

We also know that everything beyond Earth,

everything we can see in the universe, is made of those same 92 elements.

And notice that I didn't say we think that's what they're made of.

I said we know that's what they're made of,

because we can prove it.

The chemistry set we have on Earth extends far beyond the planet.

We have set foot on the moon

and know that it's rich in helium, silver and water.

We've sent robot landers to our neighbouring planets

and discovered that Mars is rich in iron,

which has combined with oxygen to form its familiar rusty red colour.

And we know that Venus' thick atmosphere is full of sulphur.

We've sent spacecraft to the edge of the solar system

to discover that Neptune is rich in organic molecules like methane.

But what of the rest of the universe?

It seems impossible that we could discover what the stars are made of

because they're so far away.

Even the nearest star, Proxima Centauri,

is ten thousand times more distant than Neptune,

4.2 light years from Earth.

And the nearest galaxy, Andromeda, is another 2.5 million light years away.

Yet despite these vast distances,

these alien worlds are constantly sending us signals,

telling us exactly what they are made of.

Our only contact with the distant stars

is their light that's journeyed across the universe to reach us.

And encoded in that light

is the key to understanding what the universe is made of.

And it's all down to a particular property of the chemical elements.

You see, when you heat the elements, when you burn them,

then they give off light.

And each element gives off its own unique set of colours.

So this is strontium and it burns with a beautiful red colour.

Sodium is yellow.

Potassium is lilac.

And copper is blue.

Each element has its own characteristic colour.

It's this property that tells us what the stars are made of.

But it's a little more complicated

than simply looking at the colour of the light that each star emits.

You can see why by looking at the light from our nearest star, the sun.

This is a spectrum of the light taken from our sun.

And at first glance it looks very familiar,

it looks like a stretched-out rainbow,

because that's exactly what a rainbow is,

it's the spectrum of the light from the sun in the sky.

But if you look a bit more closely,

then you see that this spectrum is covered in black lines.

These are called absorption lines.

Each element within our sun

not only emits light of a certain colour,

it also absorbs light of the same colour.

By looking for these black lines in the sun's light,

we can simply read off a list of its constituent elements, like a barcode.

For example, these two black lines

in the yellow bit of the spectrum are sodium.

You can see iron. Right down here, you can see hydrogen.

So by looking at these lines in precise detail,

you can work out exactly what elements are present in the sun.

And it turns out that that's about 70% hydrogen,

28% helium and 2% the rest.

And you can do this not only for the sun,

but for any of the stars you can see in the sky,

and you can measure exactly what they're made of.

So that star there is Polaris, the pole star. And you can see that

because all the other stars in the night sky appear to rotate around it.

Now, it's 430 light years away.

But we know just by looking at the light

that it has about the same heavy element abundance as our sun,

but it's got markedly less carbon and a lot more nitrogen.

And the same applies for other stars.

Vega, the second brightest star in the northern sky,

has only about a third of the metal content of our sun,

whereas other stars are metal-heavy.

Sirius, the dog star, contains three times as much iron as the sun.

And Proxima Centauri is rich in magnesium.

But although the quantities of the elements may vary,

wherever we look across space,

we only ever find the same 92 elements that we find on Earth.

We are made of the same stuff as the stars and the galaxies.

But where did all this matter come from?

And how did it become the complex universe we see today?

In order to understand where we came from,

we have to understand events that happened

in the first few seconds of the life of the universe.

You see, when the universe began, it was unimaginably hot and dense.

We literally don't have the scientific language to describe it.

But it was, in a very real sense, beautiful.

There was no structure, there was certainly no matter.

It was exactly the same, whichever way you look at it.

We can get some idea of how the universe developed

from this state of pure symmetry

by looking at the behaviour of water in this remarkable landscape.

These are the El Tatio geysers, high in the Chilean Andes.

As the boiling water bubbles up through the ground

to meet the freezing mountain air,

water can be found in all three of its natural phases,

vapour, liquid and ice.

In its hottest state, water is, like the early universe,

an undifferentiated cloud.

But as it cools, it suddenly behaves very differently.

You see, if you look at a cloud of steam,

it looks the same from every direction,

but as it cools down, as it lands on this plate of freezing cold glass,

then it immediately crystallises out, it turns into solid water, ice.

As the ice crystals form,

the symmetry of the water vapour disappears from view

and complex, beautiful structure emerges.

In the same way, we think that the universe, as it cooled,

went through a series of these events where structure emerged.

One of the most important

was about a billionth of a second after the Big Bang.

In that moment, an important part of the symmetry of the universe was broken.

Known as electroweak symmetry breaking,

this was the moment when subatomic particles acquired mass,

substance for the first time.

Amongst them were the quarks.

As the universe continued to cool,

those quarks joined together to form larger, more complex structures

called protons and neutrons.

Way before the universe was a minute old,

the quarks had been locked away inside the protons and the neutrons.

They are the building blocks of all atomic nuclei,

the building blocks of the elements.

These same protons and neutrons are with us to this day.

They form the hearts, the nuclei, of all atoms.

Just a few seconds after the beginning of the universe,

the fundamental building blocks of everything had been created.

Well, it sounds ridiculous.

The fact that everything you need to make up me

and everything on planet Earth

and, in fact, every star and every galaxy in the sky

was there after the first minutes in the life of the universe.

It's almost unbelievable,

but we have extremely strong experimental evidence

to suggest that that is the way that it is.

Well, from that point on, it was just, in a sense,

a process of assembling those bits into more and more complex things.

That is an incredibly fascinating story in itself.

To tell that story,

we must look deep inside the atom, to the nucleus at its centre.

Here we can see how protons and neutrons are assembled

to build up the 92 different elements.

Now, the wonderful thing about the construction of the chemical elements

is that it's so simple.

I suppose you could call it child's play.

So imagine these bubbles are my universal chemistry set.

And the single bubbles would just be single protons.

That's the nucleus of the simplest chemical element.

The element with a single proton in its nucleus is hydrogen.

And from hydrogen, you can make all the other elements.

The first stage is to stick two protons together.

(LAUGHS) Look at that! That was two bubbles stuck together.

Now, what happens when you stick two protons together is

one of the protons turns into a neutron.

And that is called deuterium.

Deuterium is still a form of hydrogen,

because it has only one proton in its nucleus

and it is the number of protons that defines the element.

It's only when two deuterium nuclei are combined

that a new element is created.

Take two deuteriums and fuse them together

and you get a nucleus with two protons and two neutrons.

That's helium, the second simplest element.

And then it's just a question of adding more and more protons and neutrons.

Well, there's an incredibly complicated nucleus.

That's about 12 things stuck together.

So that would be probably carbon-12, which is six protons and six neutrons.

And you can carry on building more and more complex elements

all the way up to the heaviest element in the universe,

to uranium and beyond.

Simple and beautiful physics.

This process of building the elements is called nuclear fusion.

It allows the simplest of ingredients

to create the infinite variety of the universe.

But although this bubble metaphor makes creating new elements seem simple,

it is in reality incredibly difficult to achieve...

so difficult that there's only place in nature that it happens.

It's in stars like our sun that the elements are assembled.

They are the only places in the universe hot enough and dense enough

to fuse atoms together.

Even then, only a fraction of the star

reaches the extreme temperatures necessary.

The sun is 6000 degrees Celsius at its surface,

not nearly hot enough to power fusion.

But deep below, where the temperature reaches 15 million degrees,

the sun fuses hydrogen into helium at a furious rate.

Every second it burns 600 million tonnes of hydrogen.

As it does so, it releases the huge amounts of heat and light

that brings our planet to life.

It is this process of converting one element into another

that allows us to exist.

But for all its power, the sun only converts

hydrogen, the simplest element, into helium, the next simplest.

But there are over 90 other elements present in our universe.

So where did they all come from?

If the heavier elements are not being made in stars like the sun,

then there must be somewhere else in the universe where they are assembled.

It's important to know,

because it's the elements beyond helium that give our world its complexity.

And when it comes to planet Earth and human beings,

there's one element that is particularly important.

Carbon.

Life is completely dependent on carbon.

I mean, I'm made of about a billion billion billon carbon atoms,

as is every human being out there, every living thing on the planet.

Imagine how many carbon atoms that is.

So where does all that carbon come from?

Well, it comes from the only place in the universe where elements are made.

Stars.

But in order for us to live, a star must die.

Stars in the prime of their lives, like our sun,

are only hot enough to make helium.

Forming the heavier elements requires much higher temperatures,

temperatures that can only be reached at the end of a star's life.

Looking out into space,

you might think that the cosmos is a constant, unchanging place,

the stars will always be there.

But in fact, the stars are only a temporary feature in the sky.

And though they may burn brightly for many millions or billions of years,

they can only live for as long as they have a supply of hydrogen to burn.

When a star runs out of hydrogen, it begins to die.

But it doesn't go quietly.

Rather than cooling, the star becomes much hotter,

until there's a sudden flash.

Then the star starts to expand.

Over tens of thousands of years,

it balloons to many hundreds of times its previous size.

But in this bloated state,

the star is unable to maintain its surface temperature.

As it cools, it takes on the characteristic colour of a dying star.

It has become a red giant.

These are pictures of a red giant star in our galaxy,

a star called Betelgeuse.

Now, it's one of our nearest neighbours in cosmic terms,

it's only about 600 light years away.

But it's the size that's astonishing.

If you were to put the sun there, then Venus would be about there,

and the Earth about there, and Mars here.

And in fact, you could fit everything in the solar system

all the way out to Jupiter inside the star.

Now, because it's so big, even though it is 600 light years away,

you can see detail on its surface.

So these, these are sunspots on the surface of Betelgeuse.

But it's not what's going on on the surface that's really interesting.

To understand where carbon comes from in the universe,

we have to understand what's going on deep in the heart of the star.

Imagine this old prison in Rio is a dying star like Betelgeuse.

Out there is the bright surface, shining off into space.

As I descend deeper and deeper into the prison,

the conditions will become hotter and hotter and denser and denser,

until down there, in the heart of the star, is the core,

and it's in there that all the ingredients of life are made.

Deep in its core,

the star is fighting a futile battle against its own gravity.

As it desperately tries to stop itself collapsing under its own weight,

new elements are made in a sequence of separate stages.

Stage one is while there is still a supply of hydrogen to burn.

Whilst the star is burning hydrogen to helium in the core,

vast amounts of energy are released, and that energy escapes,

literally creating an outward pressure which balances the force of gravity

and, well, it holds the star up and keeps it stable.

But eventually the hydrogen in the core will run out

and at that point, the fusion reactions will stop,

no more energy will be released,

and that outward pressure will disappear.

Now, at that point, the core will start to collapse very rapidly,

leaving a shell

of hydrogen and helium behind.

Beneath this shell, as the core collapses,

the temperature rises again,

until, at a hundred million degrees, stage two starts

and helium nuclei begin to fuse together.

Now, helium fusion does two things.

Firstly, more energy is released, and so the collapse is halted.

But secondly, two more elements are produced in that process.

Carbon,

oxygen. Two elements vital for life.

So this is where all the carbon in the universe comes from.

Every atom of carbon in my hand,

every atom of carbon in every living thing on the planet

was produced in the heart of a dying star.

Now, compared to the lifetime of a star,

the creation process of carbon and oxygen is over in the blink of an eye,

because in only about a million years,

the supply of helium in the core is used up,

and for stars as massive as the sun, that's where fusion stops,

because there isn't enough gravitational energy

to compress the core any further and restart fusion.

But for massive stars like Betelgeuse, the fusion process can continue.

When the helium runs out,

gravity takes over again and the collapse continues.

The temperature rises once more, launching stage three,

in which carbon fuses into magnesium, neon, sodium and aluminium.

And so it goes on, core collapse,

followed by the next stage of fusion to create more elements,

each stage hotter and shorter than the last.

And eventually, in a final stage that lasts only a couple of days,

the heart of the star is transformed into almost pure iron,

whose chemical symbol is Fe.

This is where the fusion process stops.

In its millions of years of life,

the star has made all the common elements,

the stuff that makes up 99% of the Earth.

The core is now a solid ball of those elements,

stacked on top of each other in layers.

On the outside, there's a shell of hydrogen,

beneath it a layer of helium,

then carbon and oxygen and all the other elements,

all the way down to the very heart of the star.

And once that has fused into solid iron,

the star has only seconds left to live.

When a star runs out of fuel,

then it can no longer release energy through fusion reactions,

and then there's only one thing that can happen.

In about the same amount of time it takes this prison block to crumble,

the entire star falls in on itself.

This is the destiny that awaits most of the stars in the universe.

Yet even the implosion of a star only forges the first 26 elements.

What of the remaining elements, some of which are vital for life,

and many of which we hold most precious?

(BIRDS CHIRPING)

These are the remote forests of northern California.

A hundred years ago, this whole area was teeming with people,

all in search of one element.

And the reason they were here can still be found

in the Original Sixteen to One mine.

This once stood at the centre of the California gold rush.

And thanks to a quirk of geology,

it continues to yield its precious bounty over a hundred years later.

The unique thing about this place is that it sits right on the divide

between the North American plate and the Pacific plate.

You see a divide there, between the rock and quartz.

And then right up there you can see the top of it.

Now, in between the faults, this rock, the quartz, formed.

Then 140 million years ago, in the Jurassic period,

when the dinosaurs were running around above our heads,

hot water welled up and flowed.

And that water deposited the gold through the seams of quartz.

And so, all the miners have to do,

all they have to do is follow the seams of quartz,

and over hundreds of years they've found vast amounts of gold deposited there.

Well, this is what all the fuss is about.

This is the gold as it comes out of the ground.

And it's unusually pure, as gold goes. This is about 85% pure gold.

But it can also be found like this.

And this is a gold nugget that was found in a river, on a riverbed.

And it's a heavy piece of gold,

it's between about one and one and a half ounces,

which means that at today's prices, it's worth about $2,000.

And it's that inherent value that makes mines like this worth operating.

(PIANO PLAYING)

But there's something a bit odd about the value we attach to gold.

Throughout history, people have gone to extraordinary lengths

to get their hands on this most precious substance.

Which is strange, because it isn't particularly useful for anything.

Most of the gold that's been extracted throughout human history

has ended up as jewellery.

But it has got one thing going for it, and that's that it is incredibly rare.

All the gold mined from the Earth in all of human history

would only just fill three Olympic-sized swimming pools.

And it's that scarcity that makes gold valuable.

But gold is just one of many rare elements.

There over 60 elements heavier than iron in the universe.

Some are valuable like gold, silver, platinum.

Some are vital for life, like copper and zinc.

And some are just useful. Like uranium, tin and lead.

But across the universe,

there are vanishingly small amounts of those heavy elements.

The reason for that scarcity

is that creating substantial amounts of the heaviest elements

requires some of the rarest conditions in the universe.

And we need to look far into space to find them.

In a galaxy of a hundred billion stars,

these conditions will exist, on average, for less than a minute in every century.

That's because they are only created

in the final death throes of the very largest stars,

stars of at least nine times the mass of our sun.

Only they can reach the extreme temperatures needed

to create large amounts of the heavy elements.

Deep in the heart of the star, the core finally succumbs to gravity.

It falls in on itself with enormous speed...

and rebounds with colossal force.

As the blast wave collides with the outer layers of the star,

it generates the highest temperatures in the universe,

a hundred billion degrees.

These conditions last for just 15 seconds,

but it's enough to form the heaviest elements, like gold.

It's called a supernova,

the most powerful explosion in the universe.

You know, it's quite a thought that something as precious to us

as the gold in a wedding ring

was actually forged in the death of a distant star

millions of light years away, billions of years ago.

Despite the rarity of supernovae,

when they do happen, they are the most dramatic events in the sky.

This is a picture of the Tarantula Nebula,

which is a cloud of gas and dust

in the Large Magellanic cloud, which is a satellite galaxy of the Milky Way.

And this is what it looks like on any clear, starry night of the year.

But on one night in 1987, the Tarantula Nebula looked like that.

You see that a new, bright star has appeared in the sky.

This is a supernova explosion, the explosive death of a massive star.

And they are incredibly violent cosmic events,

as this picture beautifully shows.

This is a galaxy about 55 million light years away from Earth,

but this is a supernova explosion in that galaxy.

And you see that it is shining as brightly as the galactic core.

There may be a billion suns in that core,

and one supernova can shine as brightly as that.

Yet to really appreciate the scale of these explosions,

we would need to see one up close,

to see a star die in our own galaxy, the Milky Way.

Although on average there's one big supernova in each galaxy every century,

there hasn't been one in the Milky Way since the birth of modern science.

The last was in 1604, so we're long overdue.

Astronomers are now searching the skies

for the star that is most likely to go supernova.

And amongst the leading candidates, there's a familiar name.

This is the constellation of Orion, and this is Betelgeuse.

And we know it's extremely unstable

because it's dimmed by about 15% in the last 10 years.

Now, astronomers think that this star could go supernova at any moment.

That could mean any time in the next million years,

but equally it could explode tomorrow.

And Betelgeuse is only 600 light years away.

Now, when it goes, Betelgeuse will be incredibly bright.

It will be by far the brightest star in the sky.

It may shine as brightly as a full moon.

It will be almost a second sun in the daylight.

In this single instant, Betelgeuse will release more energy

than our sun will produce in its entire lifetime.

As the star is torn apart, it will fire out into space

all the elements that it created in its life and death.

Those elements will spread out to become a nebula,

a rich chemical cloud drifting through space.

And at the heart of the nebula will be a tiny beacon of light,

the remnant of a star, once more than a billion and a half kilometres across,

that has been crushed out of all recognition by gravity.

This is Betelgeuse, the neutron star.

And it's how this once mighty star will end its life.

Now, once Betelgeuse is gone,

the constellation of Orion will look very different.

I mean, there'll just be a hole in the sky

where that brilliant, bright red star once shone.

But it's in the deaths of old stars that new stars are born.

It's very much like the cycle of death and rebirth here on Earth,

but played out on a cosmic scale.

And you can see that happening today in the constellation of Orion,

because in the sword handle, you can see this, the Orion nebula.

Now, it's nothing more than

a misty patch of light in the night sky to the naked eye.

But if you look more closely, you see that there is a lot more going on.

The Orion nebula is one of the wonders of the universe.

Hidden in its clouds are bright points of light.

These are new stars

forming from the elements blown out by supernova explosions.

New stars being born from the remains of dead ones.

And it's from this universal process of death and rebirth that we emerged,

because it was in a nebula just like this, five billion years ago,

that our sun was formed.

Around it, a network of planets formed.

Among them was the Earth.

Everything we find on the Earth today also originated in that nebula.

But that is not the end of the story of how the universe created us.

Because when we look deep into the nebula,

we don't just see individual elements,

we see greater complexity, the seeds of our own existence.

This is a spectrum of the light from the Orion nebula

taken by the Herschel space telescope.

So it really is a picture of light from interstellar space.

You know, I wouldn't normally show you a graph like this,

but this is fascinating, because what it shows

is that that gas cloud, the Orion nebula,

is not just a cloud of elements.

There's complex chemistry here happening in deep space.

Because each peak on this graph corresponds to a different molecule

and there are some molecules present that I suppose are quite obvious.

There's water, there's sulphur dioxide.

But there are also complex carbon compounds in here.

So there's methanol, there's hydrogen cyanide,

there's formaldehyde, there's dimethyl ether.

So what we're seeing here is complex carbon chemistry

happening in deep space.

That carbon chemistry is the beginning of the chemistry of life.

And there is surprising evidence that this chemistry

may have had a direct impact on the evolution of life on Earth.

That evidence comes from meteorites,

debris left over from the formation of the solar system

that occasionally collides with the Earth.

One of the most productive places for finding meteorites

is the Atacama Desert in the High Andes of South America.

This is a meteorite,

a piece of rock that fell to Earth from somewhere out there in the solar system.

And it is certainly older than any rock you can see here.

It's probably older than any rock you can find anywhere on Earth,

because it formed from the primordial gas cloud,

that nebula that collapsed

to form the sun and the planets over four and a half billion years ago.

So it's incredibly ancient.

Now, this is a slice, a cross-section through a meteorite.

You see those little brown areas in there?

Well, in those brown areas we've found amino acids,

the building blocks of proteins,

which are the building blocks of me, the building blocks of life.

Incredibly complex carbon compounds.

So this says that the complex carbon chemistry you need

to send you on the path to life

was happening out there in space four and a half billion years ago.

So the first amino acids on Earth, the fundamental building blocks of life,

may have formed in the depths of space

and been delivered to the Earth on meteorites.

When we look out into space, we are looking into our own origins,

because we are truly children of the stars.

And written into every atom and every molecule of our bodies

is the entire history of the universe, from the Big Bang to the present day.

Our story is the story of the universe.

Every piece of everyone,

of everything you love and everything you hate,

of the thing you hold most precious, was assembled by the forces of nature

in the first few minutes of the life of the universe,

transformed in the hearts of stars or created in their fiery deaths.

And when you die,

those pieces will be returned to the universe

in the endless cycle of death and rebirth.

What a wonderful thing it is to be a part of that universe.

And what a story, what a majestic story.

(ACROSS THE UNIVERSE BY DAVID BOWIE PLAYING)