Forces of Nature with Brian Cox (2016) s01e02 Episode Script
Somewhere in Spacetime
1 The natural world is beautiful but complex.
The skies dance with colour.
CHEERING Shapes of great geometrical beauty form and disappear.
And the planet itself is constantly transformed.
But this seemingly infinite complexity is the shadow of something deeper.
The underlying laws of nature.
The world we live in is beautiful to look at.
But it's even more beautiful to understand.
Everything in the universe is in motion.
And yet it feels as if we're standing still.
This appears to be such a simple observation, but the study of motion lies at the very foundation of modern physics and leads to the astonishing conclusion that the division of time into past, present and future is an illusion.
Our intuition is wrong.
Space and time are stranger than we could possibly have imagined.
From our viewpoint here on Earth, the planet seems motionless, as the universe revolves around us.
Every day for four-and-a-half-billion years, the sun has risen in the east, tracked across the sky and set below the western horizon.
And as the years pass, so the seasons turn.
Summer fades into autumn .
.
and autumn into winter.
But these seemingly perpetual cycles are delicate, evocative hints that our planet is far from stationary.
I've always loved the passing of the seasons.
A gentle experience with a powerful resonance.
I always remember the words of those hymns that I used to sing when I was six or seven that celebrate them.
"Let me plough the fields and scatter", "In the bleak midwinter, the frosty winds made moan.
" The daily changes are almost imperceptible.
The reddening of the leaves and the cooling of the streams is subtle.
But those changes mask a jarring, celestial violence.
So what is going on out there in space, in time, as the days pass, the seasons change? The most familiar aspect of our planet's motion is the day, caused by the Earth's rotation.
You'd have to go back to the turn of the 17th century to find anyone who would argue that the Earth doesn't spin.
But you need a piece of 21st century technology to experience just how fast it's moving.
We're going to get ourselves airborne from Wharton, here, and then we're going to climb up to altitude and were going to try and beat the Earth's rotation.
The Earth spins so fast that you can't beat it with any old crate.
You need something a bit special.
This is a Eurofighter Typhoon.
It flies at least Mach 1.
85 - twice the speed of sound.
I can't tell you exactly how fast, because it's classified.
They go to at least 55,000 feet, but again, I can't tell you - it's classified.
And you can't film down those air intakes, because they're classified, as well.
This one is BAE Systems' development aircraft - I'm going to get in it in a minute - and it's got all the test software in.
The pilot told me that, you know, it's a bit ropey, so press control, alt, delete occasionally if it all goes funny and usually it comes back on.
Which is good.
Get in.
Feet-wise, comfy? Good.
That's for if you need to control it at any point.
- It's unlikely! - Unlikely.
Sick bag? Right.
Worst comes to the worst, do it in your glove.
'Time is 6-9, runway 0-7, clear takeoff.
' Surface wind 350 degrees, seven knots.
Over on cable.
- Ready? - Yeah.
- Go for it.
And we're off.
Oh, lovely and bright.
MUSIC: Blue Orchid by The White Stripes Oh! # You got a reaction, didn't you? # You took a white orchid # You took a white orchid and turned it blue # Something better than nothing Something better than nothing It's giving up - I have to say, that's the way to depart an airfield.
- It is a bit.
You see, on the east side, everything is darkening up quite nicely as the sun starts to set.
And on the ground, it's already It's dark on the ground now, as far as the sun is concerned.
Accelerating.
So that's Mach .
78.
- Yeah.
- And the G-suit is inflating.
- Yeah.
'Turning directly towards the setting sun, 'the Typhoon accelerates to catch up with the Earth's spin.
'Beneath us, a 6,000 billion, billion-tonne rock is spinning at 650 mph.
'Match that speed and something interesting happens 'to the sun's motion across the sky.
' 650 mph, so we are travelling at precisely the speed of the Earth's rotation.
- That's right.
- So we stop the sun, it's about two thirds down.
So it should just stay there now, because we're going at exactly the same speed as the Earth.
'But travel faster than the planet's surface, 'and the normal passage of the day is reversed.
' Right, accelerating.
Accelerating.
Oh, there we go.
- That's acceleration.
- Mach 1.
Through the sound barrier.
'As the jet accelerates, 'it starts to overtake the spin of the Earth '.
.
causing the setting sun to rise again.
' Starting to grow a little.
It is, I can see it.
We are beating the Earth! Absolutely terrific.
- Starting to climb again, you can see it.
- Yes.
That's Mach 1.
4.
So it's 1,000 miles an hour.
We're doing almost 1,000 miles an hour.
And now the sun, it's almost a full vista with the clouds.
- The sunrise! - It is.
Two sunrises in one day! And all you need is the world's most advanced fighter aircraft.
There we go.
Beautiful.
We've done it, we've outrun the Earth! BRIAN LAUGHS - Goodbye, sun! - Yes, right.
Let's get ourselves on our way home.
Do me a favour.
We've had a bit of a quarrel with Lambeth parking services.
THEY LAUGH Just one last favour before we left.
THEY LAUGH RADIO CHATTER So that worked beautifully well.
What happens when you light those engines on full, accelerate up to 1.
4 times the speed of sound, you can't tell you're going at that speed at all, apart from the fact that out in the front of the cockpit, the sun just gently rises up again in the West, over Ireland.
And then you put the brakes on and your face goes funny.
But it was terrific.
Thank you.
THEY LAUGH And for the tape, he wasn't ill.
THEY LAUGH To turn on its axis once every 24 hours, the Earth is spinning at breakneck speed.
At the equator, where the ground has furthest to travel each day, its speed exceeds 1,000 miles an hour.
Which presents a deep paradox.
Here, right now, on a lazy spring day in the south of England, this piece of ground is thundering along at 650mph, and yet, I can't feel it.
And when you think about it, that's a very strange thing.
I mean, what is motion if you can't perceive it? Well, the answer is a deep one.
You can't perceive that you're moving if you're travelling in a straight line at a constant speed.
And that's a fundamental property of nature.
It's the way our universe is constructed.
So I don't feel that I'm moving from minute to minute, because I'm almost moving in a straight line.
I have to make it round in a circle, but it's 15,000 miles around and I have 24 hours to do it.
Although we don't experience the sensation of moving around our planet's axis, we do experience events that are a direct consequence of living on a spinning globe.
In the Philippines, the warmth of the tropical sun and the spin of the Earth conspire to produce some of the most extreme weather on the planet.
And for the people who live here, it poses an ever-present threat.
With the kids out of the way, Leanilla begins the work she hopes will allow them to leave Tacloban for ever.
Every time it rains, darker memories rise to the surface.
Three years ago, driven by heat rising from the tropical waters, a storm formed over the Pacific Ocean.
As it tracked north, the Earth's rotation gave rise to a force known as the Coriolis force, which acted on the air falling into its low-pressure heart, causing the storm to spin, increasing its intensity.
So what began as a tropical storm at sea hit Tacloban as a category five super-typhoon.
Leanilla's family were caught directly in its path.
Leanilla took the children and sought shelter in the local church - the only solid structure in the neighbourhood.
But while the family were in the relative safety of the church, Leanilla's husband was caught up in the chaos raging outside.
Boosted by the Coriolis force, winds approaching 200mph whipped up the ocean .
.
into a devastating storm surge.
Over 90% of the city was destroyed .
.
leaving Leanilla with an anxious wait for news of her husband.
Exposed to the full force of the storm, Juvie had been swept inland for more than a mile.
The Hernandez family experienced a singular event that affected their lives dramatically and directly.
The Coriolis force that caused it isn't a fundamental force of nature in its own right.
It appears because of the Earth's rotation.
So-called fictitious forces like this arise whenever anything spins or rotates.
And because the Earth's orbital motion through space is complex - affected not only by the sun, but also the moon - there are other fictitious forces at work.
One of these plays a subtle but important role in a twice daily phenomenon with which we are all familiar.
The ebb and flow of the tides.
We usually think of the moon in orbit around the Earth as the Earth stays still.
But that's not quite right.
Actually, they are both in orbit.
They are in orbit around a point called the common centre of mass of the Earth-Moon system.
Essentially, what's happening is something like that, although it's quite difficult to do.
Now, when things rotate around in circles, other forces come into play.
In this case a force called the centrifugal force.
So that's the force you'd feel if you were hanging on to a roundabout, going faster and faster and you have to hang on tighter and tighter because of the force trying to throw you off.
That's the centrifugal force.
Now, let's bring the moon back.
So now there are two forces at play in this system.
There's a gravitational pull - the moon - which pulls everything towards it, and there's that centrifugal force, trying to throw everything off.
And they are in perfect balance at the centre of the Earth.
But think about the ocean, here.
That's closer to the moon, and so the moon's gravitational pull wins and you get a tidal bulge.
Now think about this point on this side of the Earth.
That's farther away from the moon, so the centrifugal force wins, throwing the water off, and you get a tidal bulge.
Now the Earth just rotates underneath those tides once a day and that's why you get two tides every day.
On an English beach, the complex gravitational interaction between Earth and Moon is distilled into the gentle advance and retreat of the waves.
But in some parts of the world, on a few days of the year, this mismatch of the forces across the Earth unleashes something far more destructive.
For nearly 4,500 miles, the Amazon snakes through dense rainforest from its source high in the Andes to the shores of the Atlantic Ocean.
And here, close to the mouth of the river, its banks are home to the Rivieros.
In this remote part of the jungle, Joao's family are completely dependent on the river.
The Amazon is the centre of their world .
.
the place where they work and play.
But today is different.
Today, they must get away from the water.
Because this part of the river is home to a monster.
In the ancient Tupi language, Pororoca means "great roar".
A sound so loud, it can be heard ten miles away.
Pororoca When the moon and sun fall into alignment with the Earth .
.
their gravitational pull is combined .
.
causing the Pororoca to emerge from the ocean.
The Pororoca is one of the biggest and most powerful tidal waves on the planet.
A seething wall of water that engulfs everything in its path as it surges up the river for nearly 200 miles.
But as the Pororoca strikes, not everyone is trying to escape.
# My veins are blue and connected # And every single bone in my brain is electric # But I dig ditches like the best of 'em Yo trabajo duro Como en madera y yeso Serginho Laus has devoted his life to surfing the Pororoca.
Waiting for the few times a year when the Earth's orbit around the sun and the centre of mass of the Earth-Moon system provides the ultimate ride through the jungle.
Then, as suddenly it appears, the Pororoca passes .
.
leaving nothing but stories in its wake.
The tides are a familiar, everyday result of the details of the Earth's complex spinning and rotational motion, and its gravitational dance with the moon.
We experience them almost from moment to moment, certainly over the length of one lazy summer's afternoon.
But the very existence of the moon has its origins in a series of chance events way back in deep time that created this stage on which we live out our lives.
4.
6 billion years ago, the solar system formed from a cloud of gas and dust, collapsing under its own gravity.
As the cloud fell inwards, it began to spin.
And it was out of this maelstrom that our planet was forged, from colliding rock and ice.
The Earth's spin was taken from the primordial cloud out of which it formed.
With every impact, the Earth grew, until eventually .
.
the sun rose over the newly formed planet .
.
for the first time.
The first sunrise and the first day.
For around 100 million years, the young Earth circled the sun alone until, it's thought, a catastrophic impact resulted in the creation of our planet's constant companion.
It's not long after the Earth formed, a planet the size of Mars crashed into it in a glancing collision, throwing rocks and debris thousands of miles out into space.
And over time, those rocks coalesced together to form the moon.
The moon formed 15 times closer to the Earth than it is today, so it wasn't 250,000 miles away, it was ten or 15,000 miles away.
It would have been a smooth object with volcanoes just seething with lava.
An incredible sight.
The collision that formed the moon also had a dramatic and lasting effect on the Earth.
You might expect that when the planets formed out of that rotating disc of gas and dust, then they would all spin along with it.
So their spin axis would be at right angles to the disc of the solar system.
But that collision that formed the moon knocked the Earth over, so now it's at an angle of 23.
5 degrees.
And that means, as it orbits around the sun, then at some points, the northern hemisphere points towards the sun, and at other points, the northern hemisphere points away from the sun.
A random event that happened so long ago has shaped the character of our planet ever since, and we experience its legacy every day.
But these spins and orbits have had a deeper effect because they are an essential part of the stage upon which life evolved, and over billions of years natural selection has shaped the animals and plants that live on Earth in response to this celestial clockwork.
The lowly dung beetle is a beautiful example.
Their lives revolve around dung.
Eating it .
.
fighting over it .
.
before rolling it away to safety.
To aid their getaway, the beetles have evolved a trick that's intimately linked to the mechanics of the heavens.
Using specialised photoreceptors on the tops of their eyes, they track the sun as it sweeps across the sky, using it to guide them on the quickest straight-line path away from the other beetles.
But as night falls, the sun dips below the western horizon to be followed across the sky by the moon.
So, by night, nocturnal beetles navigate by moonlight.
And after the moon itself has set in the dead of night, they navigate by the light of the Milky Way.
It's as if the beetles carry an imprint of events that happened billions of years in the past.
Their unique behaviour can be traced back to the origin of the solar system.
The collisions that set our world spinning, and the catastrophic impact that created the moon.
We are separated from the violence of our planet's history by the passage of time.
Although, almost paradoxically, it's in our experience of time, the setting of the sun, the rise and fall of the tides, and the passing of the seasons .
.
that we glimpse the reality of our voyage through space and time.
It's July 10th and the northern hemisphere is tilted towards the sun.
That means the sun rises high across the sky, and that increases the amount of sunlight falling on the ground in this little part of Oxfordshire, and that heats it up.
The English summer is in full swing.
But the Earth is on the move.
A planet continuing to thunder around the sun because of the principle of inertia, its straight-line path curved into an orbit by the force of gravity.
And as the Earth moves on that orbit, the North Pole tilts away from the sun and the violence of all that celestial mechanics is distilled into the gentle sensation of a lazy summer's day, giving way to the crisp chill of autumn.
The sun rides lower in the sky and the nights draw in.
As the Earth continues a yearly voyage, the North Pole tilts still further from the warmth of the sun.
Autumn .
.
becomes winter.
The sun barely rises above the tops of the trees, and Britain is plunged into a deep freeze.
In the temperate latitudes of Oxfordshire, the passing of the seasons is relatively gentle.
But if you head north, Earth's 23-degree tilt delivers a much more powerful challenge to the people that live in these lands of midnight sun and perpetual winter night.
Sitting on the Arctic Circle, Tasiilaq experiences one of the largest seasonal temperature swings on the planet.
In summer, days are long and mild, with nearly 23 hours of daylight to enjoy.
Mmm! The dramatic seasonal shifts present elemental challenges to families like the Christiansens.
As the Earth journeys around the sun, the whole of Greenland is tilted outwards towards the cold blackness of space.
Human beings evolved in the equatorial valleys of Africa, and they're not well suited to the Arctic winter, where wind speeds exceed 100mph and temperatures plummet towards -30 Celsius.
We require all the ingenuity and skills passed down from generation to generation to survive until the sun rides high again.
To search for food, Michael, Malik and their friend Enoch must head out onto the treacherous frozen ocean.
HE SHOUTS ORDERS HE SPEAKS IN OWN LANGUAGE HE SHOUTS ORDERS They've come here because, beneath the ice, the ocean waters teem with life.
Despite appearances, the frozen depths of winter are in fact the best time to fish.
For just a few months, ice provides a platform over the ocean, giving easy access to the fish below.
A brief window in which they must catch enough to last the entire year.
Lessons learned this winter will stay with Malik for the rest of his life.
Until he becomes a hunter himself.
HE LAUGHS Our planet's motion leads to something beyond the shifts in the thickness of the ice and the lengths of the days.
It's reflected in the ever deepening relationship between father and son.
The seasonal shifts in the colours and sounds of the wood are life's response to the clockwork of the solar system.
Spring will follow winter as long as the Earth orbits the sun.
The cycle of the seasons is effectively eternal, with the Earth returning to the same place every year.
Except it doesn't return to the same place, because we don't only travel through space, we also travel through time.
We live on a spinning ball of rock, hurtling through the universe.
And yet in only a few moments does the violence of our world's motion break through.
For the most part, our planet's movement is completely imperceptible to us.
But there is a consequence of motion that affects us all more deeply than any other - our journey into the future.
Once every year, Antonio Carter comes to the Church of St Constantine to pray for his life.
In just a few hours, he will risk everything taking part in the Ardia .
.
the town's annual horse race.
A tradition that has been part of his life since childhood.
As the Earth has circled the sun, the Ardia has remained constant.
The highlight of each passing year.
GUNSHO The race itself is a perilous cat-and-mouse chase through the village's most treacherous streets, that's taken place on the same two days in July for hundreds of years.
Every year, the riders appear to take the same circuit around the same Sardinian town, at the precise moment the Earth returns to the same place in its orbit.
But the reality is different.
With every passing moment, we move to a different place in the universe.
Not just in space, but also in time.
We are hurtling into the future at the speed of light, and it's that motion we experience as the passing of time.
It's only in the last century that we've discovered just how deeply motion and time are intertwined.
We feel as if we move through space as time ticks by, but that's an illusion.
The separation of space and time is false.
The first person to realise that was Albert Einstein.
He thought deeply about motion, the idea that we can't tell whether we're moving or not, and he tried to reconcile that with our picture of the universal laws of nature.
And he found that he could do, but at the expense of jettisoning space and time as separate entities and merging them together into a unified whole, a fabric of the universe called spacetime.
In spacetime, the central idea is that of an event, a moment that has a location in space and time.
So, although I've come back to this same place, this wood, over the course of the year in summer, autumn, winter and now spring, each one of those visits is a different moment with a different location in spacetime.
As the Earth moves through spacetime, its orbit traces out a spiral as it circles the sun and races into the future.
It never returns to the same place because each moment is a different location in the fabric of the universe.
And just as the Earth travels relentlessly onwards on its path through space time .
.
so must we.
So this is how Einstein asks us to picture the sweep of our lives - the experience of living.
Our lives are series of moments and they're laid out like places on a map.
There is me as a little baby with my dad and with my grandad.
That idyllic summer, some time in the early '70s in a paddling pool with my sister.
I was about four years old.
And the perfect Christmas, with my grandparents some time back in the 1970s.
There is me when I was 20 years old with a ridiculous haircut.
I was playing a gig somewhere in the middle of Europe - in Budapest, I think.
Wedding day.
And me in Oldham where I grew up .
.
with my little boy, George.
This isn't exactly like a map.
See, I can return to these places in space - to Oldham, to central Europe, to Duluth, Minnesota - where I got married - back to Oldham again.
But I can't return to these moments, to these events in spacetime.
Because of the geometry of spacetime itself, we are compelled to move inexorably into the future.
As we all journey through spacetime, it's only in our memories that we can revisit the past.
But just because we can't go back in time .
.
doesn't mean that the past isn't out there.
If you take Einstein's universe at face value - and there's no reason why you shouldn't - it's our best theory of space and time, and this picture of spacetime with events placed within it suggests something wonderful and, I think, quite magical.
See, if I leave a place in space, then it doesn't cease to exist when I've left it, and in spacetime, if I leave an event, it doesn't cease to exist when I've left it.
So, that suggests that all those summers you spent with your mum and dad, or that first Christmas with your grandparents long ago, all those most precious memories of people and places, all those summers and winters passed and seasons yet to come are out there, somewhere in spacetime.
The skies dance with colour.
CHEERING Shapes of great geometrical beauty form and disappear.
And the planet itself is constantly transformed.
But this seemingly infinite complexity is the shadow of something deeper.
The underlying laws of nature.
The world we live in is beautiful to look at.
But it's even more beautiful to understand.
Everything in the universe is in motion.
And yet it feels as if we're standing still.
This appears to be such a simple observation, but the study of motion lies at the very foundation of modern physics and leads to the astonishing conclusion that the division of time into past, present and future is an illusion.
Our intuition is wrong.
Space and time are stranger than we could possibly have imagined.
From our viewpoint here on Earth, the planet seems motionless, as the universe revolves around us.
Every day for four-and-a-half-billion years, the sun has risen in the east, tracked across the sky and set below the western horizon.
And as the years pass, so the seasons turn.
Summer fades into autumn .
.
and autumn into winter.
But these seemingly perpetual cycles are delicate, evocative hints that our planet is far from stationary.
I've always loved the passing of the seasons.
A gentle experience with a powerful resonance.
I always remember the words of those hymns that I used to sing when I was six or seven that celebrate them.
"Let me plough the fields and scatter", "In the bleak midwinter, the frosty winds made moan.
" The daily changes are almost imperceptible.
The reddening of the leaves and the cooling of the streams is subtle.
But those changes mask a jarring, celestial violence.
So what is going on out there in space, in time, as the days pass, the seasons change? The most familiar aspect of our planet's motion is the day, caused by the Earth's rotation.
You'd have to go back to the turn of the 17th century to find anyone who would argue that the Earth doesn't spin.
But you need a piece of 21st century technology to experience just how fast it's moving.
We're going to get ourselves airborne from Wharton, here, and then we're going to climb up to altitude and were going to try and beat the Earth's rotation.
The Earth spins so fast that you can't beat it with any old crate.
You need something a bit special.
This is a Eurofighter Typhoon.
It flies at least Mach 1.
85 - twice the speed of sound.
I can't tell you exactly how fast, because it's classified.
They go to at least 55,000 feet, but again, I can't tell you - it's classified.
And you can't film down those air intakes, because they're classified, as well.
This one is BAE Systems' development aircraft - I'm going to get in it in a minute - and it's got all the test software in.
The pilot told me that, you know, it's a bit ropey, so press control, alt, delete occasionally if it all goes funny and usually it comes back on.
Which is good.
Get in.
Feet-wise, comfy? Good.
That's for if you need to control it at any point.
- It's unlikely! - Unlikely.
Sick bag? Right.
Worst comes to the worst, do it in your glove.
'Time is 6-9, runway 0-7, clear takeoff.
' Surface wind 350 degrees, seven knots.
Over on cable.
- Ready? - Yeah.
- Go for it.
And we're off.
Oh, lovely and bright.
MUSIC: Blue Orchid by The White Stripes Oh! # You got a reaction, didn't you? # You took a white orchid # You took a white orchid and turned it blue # Something better than nothing Something better than nothing It's giving up - I have to say, that's the way to depart an airfield.
- It is a bit.
You see, on the east side, everything is darkening up quite nicely as the sun starts to set.
And on the ground, it's already It's dark on the ground now, as far as the sun is concerned.
Accelerating.
So that's Mach .
78.
- Yeah.
- And the G-suit is inflating.
- Yeah.
'Turning directly towards the setting sun, 'the Typhoon accelerates to catch up with the Earth's spin.
'Beneath us, a 6,000 billion, billion-tonne rock is spinning at 650 mph.
'Match that speed and something interesting happens 'to the sun's motion across the sky.
' 650 mph, so we are travelling at precisely the speed of the Earth's rotation.
- That's right.
- So we stop the sun, it's about two thirds down.
So it should just stay there now, because we're going at exactly the same speed as the Earth.
'But travel faster than the planet's surface, 'and the normal passage of the day is reversed.
' Right, accelerating.
Accelerating.
Oh, there we go.
- That's acceleration.
- Mach 1.
Through the sound barrier.
'As the jet accelerates, 'it starts to overtake the spin of the Earth '.
.
causing the setting sun to rise again.
' Starting to grow a little.
It is, I can see it.
We are beating the Earth! Absolutely terrific.
- Starting to climb again, you can see it.
- Yes.
That's Mach 1.
4.
So it's 1,000 miles an hour.
We're doing almost 1,000 miles an hour.
And now the sun, it's almost a full vista with the clouds.
- The sunrise! - It is.
Two sunrises in one day! And all you need is the world's most advanced fighter aircraft.
There we go.
Beautiful.
We've done it, we've outrun the Earth! BRIAN LAUGHS - Goodbye, sun! - Yes, right.
Let's get ourselves on our way home.
Do me a favour.
We've had a bit of a quarrel with Lambeth parking services.
THEY LAUGH Just one last favour before we left.
THEY LAUGH RADIO CHATTER So that worked beautifully well.
What happens when you light those engines on full, accelerate up to 1.
4 times the speed of sound, you can't tell you're going at that speed at all, apart from the fact that out in the front of the cockpit, the sun just gently rises up again in the West, over Ireland.
And then you put the brakes on and your face goes funny.
But it was terrific.
Thank you.
THEY LAUGH And for the tape, he wasn't ill.
THEY LAUGH To turn on its axis once every 24 hours, the Earth is spinning at breakneck speed.
At the equator, where the ground has furthest to travel each day, its speed exceeds 1,000 miles an hour.
Which presents a deep paradox.
Here, right now, on a lazy spring day in the south of England, this piece of ground is thundering along at 650mph, and yet, I can't feel it.
And when you think about it, that's a very strange thing.
I mean, what is motion if you can't perceive it? Well, the answer is a deep one.
You can't perceive that you're moving if you're travelling in a straight line at a constant speed.
And that's a fundamental property of nature.
It's the way our universe is constructed.
So I don't feel that I'm moving from minute to minute, because I'm almost moving in a straight line.
I have to make it round in a circle, but it's 15,000 miles around and I have 24 hours to do it.
Although we don't experience the sensation of moving around our planet's axis, we do experience events that are a direct consequence of living on a spinning globe.
In the Philippines, the warmth of the tropical sun and the spin of the Earth conspire to produce some of the most extreme weather on the planet.
And for the people who live here, it poses an ever-present threat.
With the kids out of the way, Leanilla begins the work she hopes will allow them to leave Tacloban for ever.
Every time it rains, darker memories rise to the surface.
Three years ago, driven by heat rising from the tropical waters, a storm formed over the Pacific Ocean.
As it tracked north, the Earth's rotation gave rise to a force known as the Coriolis force, which acted on the air falling into its low-pressure heart, causing the storm to spin, increasing its intensity.
So what began as a tropical storm at sea hit Tacloban as a category five super-typhoon.
Leanilla's family were caught directly in its path.
Leanilla took the children and sought shelter in the local church - the only solid structure in the neighbourhood.
But while the family were in the relative safety of the church, Leanilla's husband was caught up in the chaos raging outside.
Boosted by the Coriolis force, winds approaching 200mph whipped up the ocean .
.
into a devastating storm surge.
Over 90% of the city was destroyed .
.
leaving Leanilla with an anxious wait for news of her husband.
Exposed to the full force of the storm, Juvie had been swept inland for more than a mile.
The Hernandez family experienced a singular event that affected their lives dramatically and directly.
The Coriolis force that caused it isn't a fundamental force of nature in its own right.
It appears because of the Earth's rotation.
So-called fictitious forces like this arise whenever anything spins or rotates.
And because the Earth's orbital motion through space is complex - affected not only by the sun, but also the moon - there are other fictitious forces at work.
One of these plays a subtle but important role in a twice daily phenomenon with which we are all familiar.
The ebb and flow of the tides.
We usually think of the moon in orbit around the Earth as the Earth stays still.
But that's not quite right.
Actually, they are both in orbit.
They are in orbit around a point called the common centre of mass of the Earth-Moon system.
Essentially, what's happening is something like that, although it's quite difficult to do.
Now, when things rotate around in circles, other forces come into play.
In this case a force called the centrifugal force.
So that's the force you'd feel if you were hanging on to a roundabout, going faster and faster and you have to hang on tighter and tighter because of the force trying to throw you off.
That's the centrifugal force.
Now, let's bring the moon back.
So now there are two forces at play in this system.
There's a gravitational pull - the moon - which pulls everything towards it, and there's that centrifugal force, trying to throw everything off.
And they are in perfect balance at the centre of the Earth.
But think about the ocean, here.
That's closer to the moon, and so the moon's gravitational pull wins and you get a tidal bulge.
Now think about this point on this side of the Earth.
That's farther away from the moon, so the centrifugal force wins, throwing the water off, and you get a tidal bulge.
Now the Earth just rotates underneath those tides once a day and that's why you get two tides every day.
On an English beach, the complex gravitational interaction between Earth and Moon is distilled into the gentle advance and retreat of the waves.
But in some parts of the world, on a few days of the year, this mismatch of the forces across the Earth unleashes something far more destructive.
For nearly 4,500 miles, the Amazon snakes through dense rainforest from its source high in the Andes to the shores of the Atlantic Ocean.
And here, close to the mouth of the river, its banks are home to the Rivieros.
In this remote part of the jungle, Joao's family are completely dependent on the river.
The Amazon is the centre of their world .
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the place where they work and play.
But today is different.
Today, they must get away from the water.
Because this part of the river is home to a monster.
In the ancient Tupi language, Pororoca means "great roar".
A sound so loud, it can be heard ten miles away.
Pororoca When the moon and sun fall into alignment with the Earth .
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their gravitational pull is combined .
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causing the Pororoca to emerge from the ocean.
The Pororoca is one of the biggest and most powerful tidal waves on the planet.
A seething wall of water that engulfs everything in its path as it surges up the river for nearly 200 miles.
But as the Pororoca strikes, not everyone is trying to escape.
# My veins are blue and connected # And every single bone in my brain is electric # But I dig ditches like the best of 'em Yo trabajo duro Como en madera y yeso Serginho Laus has devoted his life to surfing the Pororoca.
Waiting for the few times a year when the Earth's orbit around the sun and the centre of mass of the Earth-Moon system provides the ultimate ride through the jungle.
Then, as suddenly it appears, the Pororoca passes .
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leaving nothing but stories in its wake.
The tides are a familiar, everyday result of the details of the Earth's complex spinning and rotational motion, and its gravitational dance with the moon.
We experience them almost from moment to moment, certainly over the length of one lazy summer's afternoon.
But the very existence of the moon has its origins in a series of chance events way back in deep time that created this stage on which we live out our lives.
4.
6 billion years ago, the solar system formed from a cloud of gas and dust, collapsing under its own gravity.
As the cloud fell inwards, it began to spin.
And it was out of this maelstrom that our planet was forged, from colliding rock and ice.
The Earth's spin was taken from the primordial cloud out of which it formed.
With every impact, the Earth grew, until eventually .
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the sun rose over the newly formed planet .
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for the first time.
The first sunrise and the first day.
For around 100 million years, the young Earth circled the sun alone until, it's thought, a catastrophic impact resulted in the creation of our planet's constant companion.
It's not long after the Earth formed, a planet the size of Mars crashed into it in a glancing collision, throwing rocks and debris thousands of miles out into space.
And over time, those rocks coalesced together to form the moon.
The moon formed 15 times closer to the Earth than it is today, so it wasn't 250,000 miles away, it was ten or 15,000 miles away.
It would have been a smooth object with volcanoes just seething with lava.
An incredible sight.
The collision that formed the moon also had a dramatic and lasting effect on the Earth.
You might expect that when the planets formed out of that rotating disc of gas and dust, then they would all spin along with it.
So their spin axis would be at right angles to the disc of the solar system.
But that collision that formed the moon knocked the Earth over, so now it's at an angle of 23.
5 degrees.
And that means, as it orbits around the sun, then at some points, the northern hemisphere points towards the sun, and at other points, the northern hemisphere points away from the sun.
A random event that happened so long ago has shaped the character of our planet ever since, and we experience its legacy every day.
But these spins and orbits have had a deeper effect because they are an essential part of the stage upon which life evolved, and over billions of years natural selection has shaped the animals and plants that live on Earth in response to this celestial clockwork.
The lowly dung beetle is a beautiful example.
Their lives revolve around dung.
Eating it .
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fighting over it .
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before rolling it away to safety.
To aid their getaway, the beetles have evolved a trick that's intimately linked to the mechanics of the heavens.
Using specialised photoreceptors on the tops of their eyes, they track the sun as it sweeps across the sky, using it to guide them on the quickest straight-line path away from the other beetles.
But as night falls, the sun dips below the western horizon to be followed across the sky by the moon.
So, by night, nocturnal beetles navigate by moonlight.
And after the moon itself has set in the dead of night, they navigate by the light of the Milky Way.
It's as if the beetles carry an imprint of events that happened billions of years in the past.
Their unique behaviour can be traced back to the origin of the solar system.
The collisions that set our world spinning, and the catastrophic impact that created the moon.
We are separated from the violence of our planet's history by the passage of time.
Although, almost paradoxically, it's in our experience of time, the setting of the sun, the rise and fall of the tides, and the passing of the seasons .
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that we glimpse the reality of our voyage through space and time.
It's July 10th and the northern hemisphere is tilted towards the sun.
That means the sun rises high across the sky, and that increases the amount of sunlight falling on the ground in this little part of Oxfordshire, and that heats it up.
The English summer is in full swing.
But the Earth is on the move.
A planet continuing to thunder around the sun because of the principle of inertia, its straight-line path curved into an orbit by the force of gravity.
And as the Earth moves on that orbit, the North Pole tilts away from the sun and the violence of all that celestial mechanics is distilled into the gentle sensation of a lazy summer's day, giving way to the crisp chill of autumn.
The sun rides lower in the sky and the nights draw in.
As the Earth continues a yearly voyage, the North Pole tilts still further from the warmth of the sun.
Autumn .
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becomes winter.
The sun barely rises above the tops of the trees, and Britain is plunged into a deep freeze.
In the temperate latitudes of Oxfordshire, the passing of the seasons is relatively gentle.
But if you head north, Earth's 23-degree tilt delivers a much more powerful challenge to the people that live in these lands of midnight sun and perpetual winter night.
Sitting on the Arctic Circle, Tasiilaq experiences one of the largest seasonal temperature swings on the planet.
In summer, days are long and mild, with nearly 23 hours of daylight to enjoy.
Mmm! The dramatic seasonal shifts present elemental challenges to families like the Christiansens.
As the Earth journeys around the sun, the whole of Greenland is tilted outwards towards the cold blackness of space.
Human beings evolved in the equatorial valleys of Africa, and they're not well suited to the Arctic winter, where wind speeds exceed 100mph and temperatures plummet towards -30 Celsius.
We require all the ingenuity and skills passed down from generation to generation to survive until the sun rides high again.
To search for food, Michael, Malik and their friend Enoch must head out onto the treacherous frozen ocean.
HE SHOUTS ORDERS HE SPEAKS IN OWN LANGUAGE HE SHOUTS ORDERS They've come here because, beneath the ice, the ocean waters teem with life.
Despite appearances, the frozen depths of winter are in fact the best time to fish.
For just a few months, ice provides a platform over the ocean, giving easy access to the fish below.
A brief window in which they must catch enough to last the entire year.
Lessons learned this winter will stay with Malik for the rest of his life.
Until he becomes a hunter himself.
HE LAUGHS Our planet's motion leads to something beyond the shifts in the thickness of the ice and the lengths of the days.
It's reflected in the ever deepening relationship between father and son.
The seasonal shifts in the colours and sounds of the wood are life's response to the clockwork of the solar system.
Spring will follow winter as long as the Earth orbits the sun.
The cycle of the seasons is effectively eternal, with the Earth returning to the same place every year.
Except it doesn't return to the same place, because we don't only travel through space, we also travel through time.
We live on a spinning ball of rock, hurtling through the universe.
And yet in only a few moments does the violence of our world's motion break through.
For the most part, our planet's movement is completely imperceptible to us.
But there is a consequence of motion that affects us all more deeply than any other - our journey into the future.
Once every year, Antonio Carter comes to the Church of St Constantine to pray for his life.
In just a few hours, he will risk everything taking part in the Ardia .
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the town's annual horse race.
A tradition that has been part of his life since childhood.
As the Earth has circled the sun, the Ardia has remained constant.
The highlight of each passing year.
GUNSHO The race itself is a perilous cat-and-mouse chase through the village's most treacherous streets, that's taken place on the same two days in July for hundreds of years.
Every year, the riders appear to take the same circuit around the same Sardinian town, at the precise moment the Earth returns to the same place in its orbit.
But the reality is different.
With every passing moment, we move to a different place in the universe.
Not just in space, but also in time.
We are hurtling into the future at the speed of light, and it's that motion we experience as the passing of time.
It's only in the last century that we've discovered just how deeply motion and time are intertwined.
We feel as if we move through space as time ticks by, but that's an illusion.
The separation of space and time is false.
The first person to realise that was Albert Einstein.
He thought deeply about motion, the idea that we can't tell whether we're moving or not, and he tried to reconcile that with our picture of the universal laws of nature.
And he found that he could do, but at the expense of jettisoning space and time as separate entities and merging them together into a unified whole, a fabric of the universe called spacetime.
In spacetime, the central idea is that of an event, a moment that has a location in space and time.
So, although I've come back to this same place, this wood, over the course of the year in summer, autumn, winter and now spring, each one of those visits is a different moment with a different location in spacetime.
As the Earth moves through spacetime, its orbit traces out a spiral as it circles the sun and races into the future.
It never returns to the same place because each moment is a different location in the fabric of the universe.
And just as the Earth travels relentlessly onwards on its path through space time .
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so must we.
So this is how Einstein asks us to picture the sweep of our lives - the experience of living.
Our lives are series of moments and they're laid out like places on a map.
There is me as a little baby with my dad and with my grandad.
That idyllic summer, some time in the early '70s in a paddling pool with my sister.
I was about four years old.
And the perfect Christmas, with my grandparents some time back in the 1970s.
There is me when I was 20 years old with a ridiculous haircut.
I was playing a gig somewhere in the middle of Europe - in Budapest, I think.
Wedding day.
And me in Oldham where I grew up .
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with my little boy, George.
This isn't exactly like a map.
See, I can return to these places in space - to Oldham, to central Europe, to Duluth, Minnesota - where I got married - back to Oldham again.
But I can't return to these moments, to these events in spacetime.
Because of the geometry of spacetime itself, we are compelled to move inexorably into the future.
As we all journey through spacetime, it's only in our memories that we can revisit the past.
But just because we can't go back in time .
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doesn't mean that the past isn't out there.
If you take Einstein's universe at face value - and there's no reason why you shouldn't - it's our best theory of space and time, and this picture of spacetime with events placed within it suggests something wonderful and, I think, quite magical.
See, if I leave a place in space, then it doesn't cease to exist when I've left it, and in spacetime, if I leave an event, it doesn't cease to exist when I've left it.
So, that suggests that all those summers you spent with your mum and dad, or that first Christmas with your grandparents long ago, all those most precious memories of people and places, all those summers and winters passed and seasons yet to come are out there, somewhere in spacetime.