How much time can you imagine?
A hundred years?
A thousand?
A million years?
Our earth holds clues to the immensity of time.
From its ancient beginnings and violent past,
the Earth has revolutionised how we understand time.
Time is more vast than we ever imagined.
And that's raising new questions.
About our ancestral roots.
About our connection to life's oldest secrets.
Our Earth is revealing our place in time.
And ultimately, our future.
Our whole world is shaped by time in ways that are often hidden from us.
Time for most of us is dictated by the rhythms of our daily life.
We get up in the morning, we go to work, we come back at night.
So watching the days and the years pass by can be quite disconcerting.
But what if we could see farther, to a greater horizon of time?
We know that time stretches into a past that existed before we were born.
We can also imagine it rolling on into a future long after we're gone.
Butjust how far back and how far forward does time really go?
And where do we fit into this larger timescale of life and even the Earth?
Answers to these questions
are now fundamentally changing our sense of who we are
and even what it means to be human.
In this programme,
I'm going to explore the huge scale of Earth Time,
its beginning and its end,
and our place within it.
On a rugged cliff of granite in South Dakota,
stone masons risk life and limb to create something unique.
The world's largest sculpture.
It's a memorial to Crazy Horse,
the native American chief from the 19th century.
But it's also a monument to a uniquely human sense of time,
one that allows us to imagine a future beyond our own lives.
Ruth Ziolkowskiis in charge of the carving.
This is her life's work.
I think sometimes people get into projects
such as cathedrals or carving a mountain or the sphinx
and anything that's going to take a long, long time;
they usually think oh, this is going to take me 30 or 40 years,
and then all of a sudden when you get started
it's going to be your lifetime and several more generations.
Five, four, fire...
Ruth's faith in a future that stretches far, far beyond her own life
is shared by three generations.
Monique, a sculptor, is one of Ruth's seven children.
I work here because I believe in what we're doing,
and the purpose of Crazy Horse is way more than a mountain carving.
The family is continuing the work of Ruth's husband, Korczak.
In 1940,
the young sculptor was invited by Standing Bear,
Chief of the Lakota, to create a fitting memorial to Crazy Horse,
their great warrior leader.
Korczak accepted the challenge,
and set to work with little more than ajackhammer
and a monumental ambition.
His vision for this project was so big,
I don't think he even realised what it was going to entail.
Korczak didn't think it was important to see it finished himself,
or for anyone of us to see it finished.
He said, 'the important thing is that you keep on working
and you never stop.'
Korczak kept carving away the mountain till his death in 1982.
But it's only recently,
50 years since Korczak began work,
that Crazy Horse's huge 90-foot face is complete.
It's anybody's guess exactly when the sculpture will be finished.
I don't have the foggiest idea how long it's going to take.
I honestly don't think Korczak did.
Korczak's vision reflects a deep and fundamental human belief,
that time exists far beyond our own experience.
I think it's incredible that dad could come out here
with nothing, nothing at all -
and erm to see so far into the future.
To be a part of that, it makes you very humble.
We hope it will grow and plan that it will,
and it's for the Indian people tomorrow
and on into the future for as many generations as it continues.
It's a dream that's becoming a legacy.
Such legacies rely on a uniquely human concept of time.
Our monuments testify to a certainty
that time will always continue onwards.
It stretches forwards into an unknowable future.
And back into a dim and distant past.
Our knowledge of time lies at the very heart of our humanity.
We learn from the past,
we pass on that wisdom to the future.
That's been the bedrock of our civilisation.
The relentless march of progress,
the world we live in today,
all that rests upon the accumulation of thousands of years of time.
On the wall of Einstein's office,
he used to keep photographs of all his predecessors
to remind himself of the great debt that he owed them.
In other words,
we all stand on the shoulders of giants.
There's no Shakespeare without classical Greece;
there's no Einstein without Newton;
there are no skyscrapers
without the skill
of generations of builders going back to the dawn of history.
This awareness that time stretches into a distant past
has driven us for thousands of years
to ask one of the greatest questions of humanity.
When did time itself begin?
In the 17th century,
an archbishop from Dublin decided to find out.
For James Ussher,
the beginning of time was the moment of God's creation,
of the Earth, the heavens, and all of humanity.
So he started with the old testament.
All Ussher really had to do
was add up the various ages of the patriarchs.
Because the bible tells us what age each person was when his son was born.
So, for example
Genesis 5 tell us that Adam was 130 years old when his son Seth was born.
Seth was 105 years old when his son Enoch was born.
But at the end of the Old Testament, the family trees run out.
Finally, in 1650,
he determined a date for the beginning of time.
With stunning precision.
In the very first paragraph
Ussher dates the creation of the world
to exactly the evening before the 23rd October 4004 BC.
James Ussher had established the very moment of God's creation.
Our place was at the centre of the universe,
the Earth created for our purpose.
Humanity, the Earth and time itself were six thousand years old.
Compared to our lifetime,
six thousand years is an incredible amount of time.
But around a hundred years later,
that timescale was about to be dwarfed.
For all of Ussher's library full of books,
the Earth itself was beginning to present quite a different story.
And the first man to realise there was a problem
was a Scottish farmer by the name of James Hutton.
There he is.
James Hutton spent most of his life
marvelling at natural processes, mainly on his own farm.
And his investigations would lead to an entirely new idea of time.
I'm about to look for the clues
that led Hutton to rethink the age of the earth
and overturn Ussher's six thousand year history.
Geologist Dave Thayer is going to be my guide.
Well, I think it's ironic that people used to wonder how old is the Earth?
But the answer was underneath their feet in the rocks all the time.
They were walking on the answer.
Yes, and they just didn't have the knowledge of er,
finding out how to er, open that book and read the - read the answer.
So Dave er, what are we going to see on this journey now?
We're going to gaze into an abyss of time.
Many people come to the place we're approaching,
and they don't really understand what they're looking at.
James Hutton's insights came from Scotland.
But Dave's brought me to a place
where the same features have been carved out on a much larger scale.
The Grand Canyon in Arizona.
270 miles of Colorado river flow across two states,
carving out a chasm one mile deep.
It's created a landscape on an epic scale.
Let's have a seat here.
Now Dave, the Colorado river is a small little thing.
How can the Colorado river gouge out such a huge canyon?
The river is digging the canyon deeper
at the rate of one foot every thousand years.
And in that time
it -just all this rubble is eroding down into it from the rain.
- I see. - You can imagine
how long that's taking, because it's all changed into sand as it goes.
A mile below us, the river continues to cut its path through the rock,
carrying it away in its silty waters.
So we're talking about the power of water, right?
I mean, water, water carved this cathedral out of nothing?
Yep. Yeah.
And how long has this erosion been taking place?
Well, at least five and a half million years is what they say.
Following similar clues,
Hutton realised
that Ussher's six thousand year age for earth had to be wrong.
Unimaginable eons of time were needed for water to carve out valleys.
And Hutton noticed something else.
The layers of rock revealed by erosion showed a still greater scale of time.
Now Dave, when I look at a rock, it's boring.
A rock is a rock is a rock.
But you're telling me that each rock has a story, right?
Well, that's true Michio.
Erm, er, you can see all the different colours of the layers in the canyon,
and each one has a different thing to tell.
Amazingly,
long, long before the rock was eroded away,
its layers had to have been formed.
Well, here's a nice place to see the strata.
I see yeah, right here.
Yes.
This red layer right here
would be a silt stone that formed at the edge of an ocean.
And you know,
it took probably a thousand years to form one inch of it.
A thousand years.
So you're telling me that
all of human recorded history
going right back to the Babylonians and the Egyptians
Would be just that much.
Just a few inches.
Isn't that staggering? Yeah.
So this is like a - like a time machine, basically, right.
Er, a thousand years per inch on average.
On average er, yeah.
If you - if you just took the whole
length ofjust the sedimentary rocks in the canyon
that have been deposited here.
Floods and rivers and streams and the ocean coming in.
It staggers the imagination.
It does indeed.
In fact,
just six inches of the Grand Canyon's rock face
is equivalent to Ussher's timescale for the whole of Earth's existence.
The Earth had begun to reveal the true immensity of time.
A scale of time that was inconceivable.
An unending abyss.
For me, Hutton wrote a great passage
which summarises the experience of the Grand Canyon,
and that is:
'The result, therefore, of our present inquiry
is that we find no vestige of a beginning,
no prospect for an end.'
The great vastness of Earth time had been revealed
and a scientific quest had begun.
If the Earth wasn't six thousand years old,
then just how old was it?
It's a question that has only finally been answered in the last few decades.
Sam Bowring is a specialist at dating rocks from all over the world.
Back in the 1980s,
he collected a sample from Canada which lay forgotten in his office.
It held an amazing secret.
Other than noting its presence and thinking it was pretty interesting,
I didn't actually begin to work on the rocks for another four years.
When Sam got round to study the rock,
he wanted to discover its age,
so he extracted a mineral called zircon.
Present in nearly every rock on earth,
it's a treasure to anyone interested in time.
The mineral zircon, when it forms in a rock,
incorporates uranium into its crystal structure.
So it's like a little time capsule,
because over time the uranium decays to lead.
This decay from one element to another is like a ticking clock.
It happens at a slow universal rate.
Measure the proportion of uranium to lead in the zircon
and you know the age of the rock it came from.
Like thousands of other samples,
the Canadian rock appeared unremarkable.
But when the results emerged,
Sam realised the rock's true significance.
I remember very clearly -
seeing the numbers come off the mass spectrometer on the screen.
That was the first time we knew that we had a very old rock.
The numbers indicated the longest time span he'd ever seen.
In fact, Sam had discovered the oldest fragment of Earth ever found.
Its age?
An amazing four thousand million years.
Dating rocks like Sam's opens up ever greater depths of time.
But it still doesn't answer that fundamental question:
Just how old is Earth?
The trouble is,
how do you know
when you've found the oldest rock on Earth?
And even after you find it,
how do you know that it was formed at the same time as the Earth?
Well, quite frankly, you don't.
The answer lies in something else,
something that was formed millions of miles away.
I'd like to buy this rock, please.
Right.
Here's the money.
Okay, that'll be 85 cents.
Compared to the other rocks in the shop -
- this rock looks pretty ordinary.
But this rock represents a landmark in our understanding of time.
It comes from outer space.
My rock is a fragment from a giant meteor that left this.
The Berenger meteor crater in Arizona.
300,000 tons of rock from space collided with Earth
and blew the ground apart.
The meteor was so huge,
it ripped house sized boulders from the ground.
Try to imagine a few of these flying through the air.
My fragment is part of that meteor.
It's debris from the very birth of our solar system.
When the solar system first formed,
it was full of rock and debris,
out of which the planets and the Earth condensed.
However, there were some bits and pieces of rock that did not condense.
And those leftover rocks remain,
primitive relics from the birth of the planets.
That's the origin of the meteorites.
They share a common age and common origin with the Earth.
So if you know the date of this rock, then you'd know the age of the Earth.
In 1955,
using radioactive dating on this very meteor,
scientists at last revealed the Earth's true age.
The search that had started with Ussher and Hutton was over.
I imagine that if James Hutton were still alive today
he'd be quite pleased with himself.
He set off on ajourney 200 years ago that he could never complete.
He talked about a vestige of a beginning that he would never see.
Well, today by looking at rocks,
not from Scotland but from outer space,
we can nail that number right to the wall.
Since 1955,
all ways to date the Earth have agreed.
The Earth is 4,600 million years old.
That's 4.6 billion years.
Earth time is unimaginably vast.
It's amazing
that in just a few centuries
our view of the depths of Earth time has changed so radically
that it's completely changed our conception of who we are.
How are weto comprehend this vast ocean of time?
And if we begin to understand the immensity of Earth time,
what does that mean for our sense of our place within it?
Let's say that one millimetre represents one year backwards in time.
Here we are in the present, this is me in the 21st century.
Now, if I go back 5.8 centimetres, then we reach 1947.
That's the year I was born.
Now let's talk about the Roman conquest of England.
That took place in the year 43 AD.
For that we have to go back about 195 centimetres.
To about here.
Even the length of my table represents 2,000 years.
But I want to measure out the whole of earth time.
And 4.6 billion years is going to take me a whole lot further.
On this scale,
every mile is an epoch of nearly two million years.
As the sheer depths of Earth time roll on,
a human lifespan seems so insignificant.
I've travelled two and a half thousand miles.
4.6 billion years of time.
The entire age of the Earth.
It's taken me across the whole of America,
and it's made me feel by comparison very, very small indeed.
Compared to my own 58 years, that's how vast Earth time really is.
My own lifespan is nothing but a pimple on the face of Earth time.
That's what makes 4.6 billion years so captivating, but also so unnerving.
You see, time means change.
Everything changes with time.
The world we see around us
that seems so solid and so permanent,
is literally changing right beneath our own feet.
Our Earth is constantly changing.
But it happens so slowly
that we're simply not around long enough to witness it.
This beach, for example, took millions of years to form.
You see, we can only see the effects of time through change.
And change over millions of years is almost imperceptible.
There are, however,
some places where occasionally
we're able to glimpse these changes in action.
Kalapana, 1990.
This Hawaiian fishing village faced total devastation
from the most active volcano in the world.
Kalawaya.
It's a 90 foot wall of hot molten lava rolling toward your home,
and people just stood there basically, in total disbelief...
And before that lava would hit the home,
homes would just burst into flame -
and people would cry
and er, you know, traumatised to the max, you know.
That lava buried house after house.
Kalapana has gone forever.
It lies 50 feet under a blanket of solid rock.
This was once the road to Kalapana.
For us, such violent events are catastrophic.
But for our Earth,
they are no more than the beats of a much greater timescale of change.
To understand this,
I'm going to take a closer look at the engine that drives this change.
Kalawaya, the world's most active volcano,
has been erupting continuously since 1983.
This is truly a fantastic experience to be literally
face to face with a live volcano.
We're dealing with very primeval forces here.
The power of volcanoes is basically the power of the Earth itself.
But this power isn't only a source of destruction,
it's the creator of new land.
This is one of the youngest parts of our planet,
built from countless layers of solidified lava.
Imagine that each of the Hawaiian islands was created in this fashion.
Volcanoes pushing their way through the crust of the earth,
forming islands.
Island after island after island.
This is the origin of the Hawaiian chain.
And it's still happening right before our eyes.
Over time, this process causes change on a huge scale.
This island was created by volcanoes 800,000 years ago -
and it's still growing,
at the rate of about a square mile every 20 years.
And you can actually see that process happening right over there.
Already 20 miles to the south,
3,000 feet under water,
yet another volcano is being born.
Lava is pouring out of the Earth's crust,
creating what will be the next Hawaiian island.
And in 200,000 years
that could be as big as the island that I'm standing on right now.
The creation of the entire chain of Hawaiian islands
took 43 million years.
But the Earth is a hundred times as old as that.
And in that amount of time,
our entire planet has been transformed.
From the time the Earth cooled,
its rocky crust has always been on the move.
Oceans and mountain ranges have been and gone.
Our planet today is just a snapshot in time.
250 million years ago, the globe was very different.
It was time that created the continents we recognise today.
And time will continue to transform the Earth.
But time has been crucial to another unique and extraordinary journey.
Life.
We are part of the most extraordinary story of all
part of the incredible diversity of life on our planet.
So what is ourjourney through time?
What I find remarkable is the fact that this journey is imprinted in me.
My body is like a museum.
My face, my features, my arms, my legs,
all of them bear the scars of evolution.
So if I could peer into my DNA, into my body,
I could perhaps retrace the steps
taken by my ancestors thousands of years ago.
I could take my own journey through time.
All of these marks of time are catalogued in my DNA,
logged in every one of my cells.
One part of my DNA,
mitochondrial DNA,
is the key to tracing my ancestry.
This DNA links me to all the mothers of my past.
How and when I became a Japanese American living in the 21st century
somehow is all encoded right here.
I'm sending it to a special lab in Cambridge.
Geneticist Peter Forster
has created a global map of human ancestry, all based on DNA.
By checking my sample against his database,
I'm hoping that he'll be able to find out
where my ancient forebears came from.
I've come to London to see what Peter's found.
I've been looking forward to this moment.
Hi Michio, pleased to meet you. I'm Peter Forster.
Hi Reary. How do you do?
Do take a seat.
Sure. So exciting.
So, the moment of truth.
What we've done to you is
we've determined your mitochondrial DNA sequence.
We can then trace your maternal ancestry back over generations.
I say, I think my mother would be delighted to know this too.
The interesting thing is that in Japan
we only have about three hits in a sample size of over a thousand.
That's unusual, right.
Yeah, it's not a very usual lineage, in other words.
Yeah. Um, it's interesting to see that you have cousins,
distant cousins -
- er, quite far away -
- in er, and around Tibet.
Is that right?
Your maternal lineage M9,
has its highest frequency in Tibet of the areas studied so far.
Well, that's amazing, uh?
Who - who'd have thought?
Yeah.
So life's full of surprises.
I'm a Japanese American Tibetan living in New York.
In fact, the same DNA connects us all,
back to the very first modern humans that evolved in Africa
over a hundred thousand years ago.
But what about before that?
This reorganisation of DNA lies at the heart of evolution.
Ever since people began to carefully look at rocks
they've found inside them
the remains of creatures embedded inside their layers.
I like to think of this as being a time capsule written in stone.
Now, the story of life is written in these fossils.
With specimens like these,
science has been able to piece together life's journey through time.
Because we can date the rocks, we can also date these trilobites.
They lived over 500 million years ago,
scuttling around the floor of some deep ocean.
Fossils have allowed us to chart the evolutionary chain that led,
by chance, to us.
And it all began a staggeringly long time ago.
Now the amazing thing is,
when you look at older and older rock,
you continue to see signs of life,
all the way back to the earliest life forms,
which are tiny little dots
marking the presence of single-celled organisms.
They date back to an incredible three and a half billion years ago,
back to the very beginning of life's journey.
To get a perspective of humanity's place in time,
I'm making anotherjourney.
Starting from the beginning of Earth time,
right through to the present day.
The first billion years of Earth time are lifeless.
But then, no one knows exactly how,
the first signs of life appear,
three and a half billion years ago.
These are our very first ancestors.
Now for the next two and a half billion years,
not much really happens.
The Earth is dominated by single-celled organisms or bacteria.
All they do is they live,
they divide and they die, over and over and over again.
As time passes,
it's incredible just how long it takes
before life shows any sign of change at all.
It's not until 570 million years ago that something amazing happens.
There's an explosion of new life forms in the world's oceans.
These are the ancestors of all living animals
fish, birds, even us.
It isn't long before animals are everywhere on the planet.
But it's not until around five million years ago
that something remarkable happens in ourjourney.
The first ape men appear.
This is about when our ancestors
first left the jungles and forests of Africa
to live in the grasslands and Savannahs.
That's when our ancestors begin to walk upright.
This freed up the hand.
The thumb, which was once used to swing in trees,
can now be used to make tools and to grab things.
That's when we begin to separate from the apes
and begin our long journey to become modern humans.
For us, it still seems a long, long journey
from ape men to modern humans.
But in the time span of life of Earth it's a mere stroll in the park.
Civilisations get going only a few thousand years ago.
We're just one tiny part of life's
three and a half billion year journey through time.
When we stop to think about the vastness of time
and life's journey through it,
it makes us feel so insignificant.
But it's also amazing that we're here at all,
able to think about our place in time,
and to realise that one day
humanity and all our glories will be gone.
Time erodes everything too.
99.9 per cent of all species
that have ever lived on the Earth are now extinct.
And one day we too may be erased.
Our new perspective on the vastness of Earth history
teaches us that live is very transient.
When and how we may meet our end nobody knows,
but evolution teaches us
that one day the human race too will die out.
So how far might humanity stretch into the future?
It's impossible to tell for sure.
But that doesn't stop us from imagining.
One day, 7,000 years from now,
an explorer stumbles into a cave deep inside a mountain in Nevada.
He might find something extraordinary.
It's a clock, unlike any ever built.
Designed to run for ten thousand years.
I imagine all the time
an archaeologist discovering it thousands of years from now.
Its creator, Danny Hillis, is an inventor.
To conceive this clock,
he had to ponder a future beyond our civilisation.
I've come to realise there's no way I can possibly plan for what
people are going to be like ten thousand years from now.
Will I relate to them? Will they look like me?
Will they be my descendents?
Will they be from some other part of the Earth or some other planet?
It starts raising a whole bunch of questions
that you don't normally think about.
The mechanics of the clock will be on display
so that any people of the future can see exactly how it works.
Danny's used the natural cycles of the planets
as a universal language of time.
He's reaching across time
to speak to any civilisation that might follow us.
What I want to do is say to the people of the future,
well we did see, even when -
we were going through that crazy thing that happened around
the year 2000, a few centuries around it,
even then we realised we were part of something
larger that lasted a longer time.
But even Danny's clock at 10,000 years
is nothing in Earth's timescale.
So what is our ultimate future?
When will our Earth's time be over?
The answer depends on an understanding not of life or the Earth,
but of our sun.
I'm in Arizona,
on top of the biggest solar telescope in the world.
It projects the largest live image of our sun that I'm ever likely to see.
I have never seen the sun like this before, in its full glory.
This is fantastic.
The clarity, the size.
And over here you can see a sunspot,
representing a cooler storm on the surface of the sun.
This is truly magnificent.
Our source of light and heat, the sun powers our planet.
Without it, life couldn't exist.
But our sun will not be around forever,
and when the sun dies the Earth will die too.
In the 1930s,
scientists speculated
that the sun was a gigantic nuclear furnace burning up hydrogen.
In fact, if you knew the total amount of sunlight that fell upon the Earth,
you could even estimate
how fast the sun was burning up its nuclear fuel.
You could even calculate when the sun would die.
But that was just a theory.
Until the 1st November 1952.
On an island in the Pacific,
the most powerful bomb in human history was being tested.
For the first time,
by fusing hydrogen atoms,
scientists were duplicating the very process
that drives the sun's furnace.
In some sense those hydrogen bombs
were like a piece of the sun placed on the Earth.
They confirmed the theory.
We now knew with certainty when the sun would die.
The sun is a middle aged star.
It's consumed about half its nuclear fuel,
and it will die in five billion years.
That's a certainty.
That's a law of physics.
We've seen the birth of Earth time, 4.6 billion years ago.
And now we know the end, in another five billion years.
The Earth is halfway through its life.
We have at last found our place in time.
Just a tiny moment in our planet's great story,
a transient fragment doomed to pass.
But maybe, just maybe, we can escape.
When I was a kid,
I used to read a lot of science fiction
because it would take me to a world of fantasy and adventure.
But in my own lifetime
I've seen many of these fantasies become reality.
We've seen the beginning of space travel,
genetic manipulation,
the computer revolution and artificial intelligence.
So I believe that the human creative spirit is truly limitless.
And I believe that perhaps our technology
may insulate us from extinction,
elevate our human culture to heights that we've never seen before,
and allow us to enter a new epic of time,
in which we could continue our remarkable journey.