[birds tweeting]
[water burbling]
[snuffling, trumpeting]
[tranquil music playing]
[Morgan Freeman] In the lives of every creature on Earth…
-[heart beating] -[whooshing]
[tranquil vocalizing]
…are echoes…
[roars]
…of events that occurred a long, long time ago.
[softly gibbering]
Events of unimaginable scale…
and violent beauty…
that connect all living things…
[dramatic vocalizing]
…their every action and decision,
their every heartbeat,
to the grandest story ever told.
This is a tale 13.8 billion years in the making…
that has seen billions of stars
and billions of worlds…
live and die…
to create the only planet we know of
that is home to life.
[dramatic vocalizing continues]
From the stardust that built us…
to the cosmic ingredients that sustain us…
and the starlight that powers it all,
this is the story of our universe.
[majestic orchestral music playing]
[mysterious music playing]
-[birds tweeting] -[animals calling]
East Africa.
It's where life's most vital connection to the universe can be found.
And a very special predator…
named Wa Chini.
Life for a cheetah is a never-ending search for food…
for vital energy.
And this is one of the hardest places on Earth for a predator to obtain it.
[sniffing]
The blistering sun has driven away nearly everything
from these dry, desolate plains.
Any creature that remains here struggles to survive.
Wa Chini's sole focus…
[tense music playing]
…the only thing driving her…
[ominous music playing]
…is hunger.
This simple, primal impulse
stems from a deep connection she has to her surroundings
that extends beyond the Serengeti,
beyond our planet
to the universe itself.
[whooshing]
Every cell in Wa Chini's body…
is linked to an ancient stream of energy…
[explosive crash]
…connecting her life
to the heart of a star.
[distorted rumbling]
[loud crashing]
This unbroken stream spans vast reaches of space…
and stretches back 13.8 billion years.
[whooshing]
[dramatic music playing]
Ancient energy that existed at the origin of our universe
powers everything.
Every planet.
Every star.
Every life.
Wa Chini is hunting for energy…
but not just for herself.
[cubs mewling]
A mother of two five-month-old cubs,
she's desperate to feed her hungry family.
It's dry season, and food is scarce.
And yet, energy is more abundant than ever.
[growls softly]
It's just hiding in plain sight.
The largest, brightest, hottest object in our solar system…
the sun.
[rumbling]
[distorted synth music playing]
Huge loops of searingly hot plasma erupt from its surface.
Our sun blasts out the energy of four and a half trillion atomic bombs
every second…
sending more power to our planet in an hour
than the entire world consumes in a year.
But as impressive as this gigantic fireball is…
Wa Chini cannot eat sunlight.
[tense music playing]
She only eats things that run…
like gazelle.
[growling softly]
Her spotted coat provides camouflage,
essential for stalking prey.
With few places to hide, getting closer isn't an option.
[tense music intensifies]
Luckily, Wa Chini has a trick up her sleeve.
[action music playing]
Cheetah are the fastest animals on land.
[breathing heavily]
From zero to a hundred in just three seconds…
but gazelles are a pretty close second.
Wa Chini uses up a lot of energy…
but gains nothing.
An adult cheetah can survive for over a week without a meal.
[panting]
But cubs, they can go no longer than a few days.
[chirps]
And these two are getting very, very hungry.
Hunting at such great speeds is incredibly depleting.
Wa Chini's energy reserves are now dangerously low.
It will be hours before she has the strength to hunt again.
Wa Chini and her cubs are running on empty.
[whooshing]
[whimsical music playing]
[softly rumbles]
Animals all over the planet fight the same ongoing battle
between consuming…
and using energy.
No matter your strategy,
be it fast or slow,
your next meal is never guaranteed.
[squawking]
Hunger is something all of us must overcome.
[somber music playing]
Having recovered from her last chase,
Wa Chini is looking for her next opportunity.
Like all cheetah mothers,
she's parenting solo.
To keep her young cubs well-fed,
she should make a kill every day.
But it's taken her so long to recover
that the sun is now setting.
[majestic vocalizing]
As the light fades,
so does this family's hopes of a meal.
[ominous music plays]
As Earth rotates…
the Serengeti turns away from the sun and into darkness.
It's a powerful reminder of life's connection to the sun.
[dramatic music playing]
Our story is the sun's story.
Long, long ago…
[whooshing]
…our solar system was even colder and darker than it is today.
And yet, these were the perfect conditions for the birth of a star.
At temperatures close to absolute zero,
the force of gravity began pulling dust and gas together…
[rumbling]
[wind howling]
…into a massive cloud.
The cloud collapsed inwards,
crushing itself into a glowing hot ball of gas.
A protostar.
[rumbling, whooshing]
[roaring blast]
Like Wa Chini, this star in the making had a ferocious hunger…
pulling in so much gas that jets of hot matter
were propelled from its poles,
stretching out light years into space.
[whooshing]
The infant star continued to grow for 30 million years…
[dramatic vocalizing]
…until finally,
it became hot enough to generate power all on its own.
Our sun.
Its golden rays have now shone brilliantly and steadily…
for 4.6 billion years.
It's just one star in a galaxy of billions.
And yet, it is a most special one…
because it is the one that delivers heat and light…
to this incredible, vibrant planet.
[birds tweeting]
Every living thing in the Serengeti depends on the sun for its energy.
Wa Chini's cubs are drained, beyond hungry now.
[purring]
They need to eat today.
But all Wa Chini can provide this morning is precious TLC.
In this parched land,
our sun both gives and takes.
Its fierce energy is what life needs.
But it also has the power to destroy.
It was never going to be easy living this close to a giant nuclear reactor.
[whooshing]
To understand the source of this unbearable heat,
we must peer into the inferno…
[rumbling]
[whooshing]
…beneath the outer layers of bubbling hot plasma…
650 thousand kilometers down…
to the core of our sun.
Our star's heart would seem surprisingly calm…
but on an atomic level, it's pure chaos.
[whooshing]
This is the hottest part of our solar system.
Temperatures here reach 15 million degrees Celsius…
creating the conditions for an event that can happen almost nowhere else.
[distorted buzzing]
[crunching, rumbling]
Atoms collide at high speed and fuse…
[explosive blast, whoosh]
…releasing pure energy.
[dramatic music playing]
This process is called nuclear fusion
and is what makes our sun shine.
[whooshing]
In fact, it's what powers all the stars in our universe.
This energy released by stars can be traced back to the beginning of time…
when there was no matter,
and all that existed in the entire universe was energy.
And every bit of it lives on in our universe today.
[invigorating music playing]
As sunlight hits the Serengeti,
energy that's been flowing for 13.8 billion years
finds its way to Wa Chini and her cubs
and continues its journey through their environment.
It is never created or destroyed.
It is simply transformed endlessly.
But Wa Chini and her Cubs can only access this energy in one form…
meat.
[sniffing]
[tense music playing]
[mewling]
And there are rival predators out here…
who could snatch not just her food but her cubs as well.
[sniffing]
[breathing heavily]
If they don't feed soon,
they will die regardless.
[action music playing]
[growling]
It's a meager snack, but after two days without food,
it's a lifesaver.
But more than 10% of cheetah kills are stolen.
[hisses, growls]
Wa Chini must defend every scrap of energy she captures…
[growls, hisses]
…because when energy is scarce,
competition is fierce.
[whooshing]
Wa Chini's struggle to survive and sustain her family is repeated
day after day…
[whooshing]
…month after month.
[majestic music playing]
Every meal is a fight.
In the battle between using and acquiring energy…
Wa Chini is only just breaking even.
Dry season on the Serengeti is defined by constant hunger.
[thunder crashing, booming]
But change is in the air.
[wind gusting]
The sun's heat has pulled what moisture there is high into the sky.
[wind whistling]
And what goes up
must eventually come down.
Rains sweep across the plains
and bring dry season to an end.
As the clouds clear,
a glimmer of hope appears.
A single blade of grass cannot feed Wa Chini's family…
but deep within its cells
lies the answer to their hunger.
[whooshing]
[stirring music playing]
Here, there's a hidden world.
Microscopic stacks called grana bask in the warm rays from the sun.
Their surface is covered with a forest of tiny, light-harvesting proteins
that capture energy from our nearest star.
They're packed with the green pigment chlorophyll,
which absorbs rays of light.
Through the magic of photosynthesis…
water combines with carbon dioxide…
and sunbeams are spun into sugar.
In a matter of days, the once parched plains are painted green.
Billions of blades of grass now soak up the boundless sunlight.
And the universe's energy becomes embedded in the landscape.
There's only one problem.
Cheetahs can't eat grass.
But far away in the northern woodlands,
there are beasts…
that do.
Hundreds of thousands of them.
Wildebeest.
They have wide mouths, flexible lips, and four stomachs
that are perfectly adapted to eating grass.
[lowing]
[dramatic music playing]
The massive herds are constantly on the move
in search of fresh grazing.
To find the grass, they follow the rain.
Driven, like all of us…
by hunger.
[lowing]
But if there is one rule in the Serengeti,
it's that food never comes easy.
The Mara River…
home to some of the largest crocodiles on Earth.
[ominous music playing]
It's a serious roadblock
in the wildebeests' quest for vital energy.
To the south, Wa Chini spends every available moment
scouring the plains for something edible.
[growls]
After six months surviving on a meager diet,
one of her cubs has managed to grow bigger…
-[cub mewls] -[mother purring]
…and is even learning some hunting skills of her own.
But the other cub is nowhere to be seen.
[melancholic music playing]
Just five percent of cheetah cubs make it into adulthood.
Most lose their lives to hungry lions and hyenas.
[growling]
This cub's future is far from guaranteed…
even when energy is tantalizingly close.
Amassed on the banks of the Mara,
the wildebeest have nowhere to go but forward.
But someone needs to be first.
[hissing]
[action music playing]
One and a half million wildebeest
make this journey each year.
And here, the battle between using and consuming energy…
plays out on an epic scale.
For those lucky enough to make it across,
this is only the beginning.
Now, they must travel hundreds of kilometers
day and night
for over two months…
to get to the grassy plains.
[tranquil music playing]
Wa Chini eagerly awaits the arrival of the wildebeest,
but there is another migration taking place that is critical
to the survival of both animals.
It's the journey of unfathomable distance and time.
And without it, every creature on the Serengeti would go hungry.
[whooshing, crashing]
[whooshing, crashing, buzzing]
In the core of our sun,
as atoms collide and fuse,
photons are released and stream outwards.
[majestic music playing]
These tiny packages of light energy have zero mass
and travel at the speed of light.
But inside the unbelievably dense core,
they're restrained, absorbed, scattered.
A trip that would normally take just two seconds can take a million years.
It's a mind-boggling torturous struggle to escape the sun.
[whooshing, crashing]
But slowly, the photons do rise
upward through the sun's layers
toward its raging hot surface…
where they can finally be set free.
[whooshing accelerates]
[electronic thud]
They radiate out in all directions…
as starlight…
traveling 150 million kilometers in just over eight minutes.
Arriving just in time…
to meet the wildebeest at the end of their journey.
Each individual blade of grass absorbs ten quadrillion photons every second…
capturing enough energy overall to feed these massive herds.
[whooshing]
From star…
[whooshing]
…to grass…
to wildebeest…
sunlight now provides them with power to move…
to grow…
to reproduce.
And the longer they're out on the plains eating,
the longer they're available to be eaten.
[tense music playing]
Rich, delicious, plentiful energy
is finally within striking distance.
[tense music intensifies]
But with three million eyes watching…
Wa Chini needs to move fast.
Luckily, she's a cheetah.
[intense music ends]
At last, Wa Chini gets a taste of starlight.
[peaceful music playing]
With every bite,
proteins and fats imbued with cosmic energy
enter Wa Chini's bloodstream.
Their final destination are her body's cellular power plants,
mitochondria…
where one last transformation will take place.
Within each mitochondrion is a surging landscape.
Canyons of membranes rippling with complex chemistry.
It's here that the energy-rich food reacts with oxygen
and is finally broken down…
releasing our universe's energy directly into Wa Chini's cells…
[whooshing]
…powering every action and thought,
every little movement.
[panting]
The journey from star to cell is complete.
Energy that once lit up the universe
now gives Wa Chini and her cub the gift of life.
In green season,
hunger is just a memory.
Across the Serengeti, energy is continually transformed…
passing from one life to another,
nourishing the entire ecosystem.
Our sun is the ultimate provider.
Everything feeds on starlight.
[tranquil vocalizing]
The trouble is, there's nothing to feed the sun.
[rumbling]
And in five billion years,
it will run out of fuel.
[ominous synth music playing]
As its core collapses,
the sun will expand…
and become a red giant…
that will devour the inner planets, Mercury and Venus.
[eerie vocalizing]
As it balloons out toward Earth,
the extreme gravity will rip our moon to shreds…
[crunching]
…leaving a ring of moon rock around Earth.
The ultimate fate of our planet is unknown.
[whooshing]
[pensive music playing]
But there will be one last sunrise…
before our star's outer layers blow away,
and it takes its final breath.
All that will remain is a dying ember,
a white dwarf,
barely the size of our Earth, surrounded by a vast glowing cloud.
A beacon to the universe.
We were here.
But right now,
our star continues to shine down on us…
[wondrous music playing]
…and will for billions of years to come,
its energy a vital force for all life.
Next in the story of our universe,
whether you are a blazing star…
a vast black hole,
or a chimpanzee learning the ropes,
everything needs time.
But what do you really know about this mysterious dimension?
Why does everything have a past, present, and future?
And would any of us be here…
without time?
[heart beating]
[dramatic ending theme playing]