Cosmos: Possible Worlds (2020) s01e12 Episode Script

1
TYSON: Welcome
to the planet Earth.
A world of blue nitrogen skies,
oceans of liquid water and
more kinds of living things
than you can possibly imagine.
(baby fussing)
You are the newest page
in its four-billion-year-old
book of life.
We're all very young here.
New, like you, to the
mysteries of the universe.
We hope someday you
will add to the little we know.
I can see a future
for you that is,
in many ways,
longer and brighter,
and more free than any human
generation has ever experienced.
I also sense danger.
That's nothing new here.
It's always been that way.
To be alive is to be in
some measure of jeopardy.
Life is dangerous.
In every generation,
in every time,
everywhere on Earth.
Our species, and
our fellow Earthlings,
have gotten through
the tough times,
when the prospects
for life looked bleak.
Somehow, we manage to endure.
And now, we want to protect you,
and your 360,000 brothers
and sisters also born on this day.
I have so much to tell
you about our world.
Some of these
stories are frightening.
But don't be afraid.
We'll find a way.
(theme music plays)
♪♪
♪♪
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TYSON: Where do I begin?
So much has happened
before you got here.
Fortunately, our ancestors
figured out a way to reach all
the way back in time to piece
together the great story of
our planet's own childhood.
And the amazing things
that have happened since.
It's called science,
and it's your birthright.
It's hard to believe that all of this
grandeur was once a sea of fire.
Come, I'll show you.
This time next year, you'll
have your first birthday.
That means you will have
completed one whole trip
around the Sun, which
is what an Earth year is.
To understand the vast
time scale of the cosmos,
and our little world, we've
squished all of time into the
scale of a single year.
And that's where we are now.
On the Cosmic Calendar.
Every month is a little
more than a billion years,
every day a little
less than forty million.
A single hour on this calendar
is almost two million years.
Earth was born in fire.
Fires within its seething heart.
And great balls of rock and
ice that explode in fiery impact.
One was almost as big as Mars,
and when it struck
Earth, it formed the Moon.
But not to worry, little one,
because those fireballs were
part of the chaotic
early solar system.
In the billions of years since,
the other worlds swept
free the lanes of their orbits.
So our solar system is a
relatively peaceful place now.
After its first
half billion years,
Earth was spinning
faster than it does today.
The days were shorter,
merely six hours long.
The Moon was ten times closer,
and its gravitational grip on the
young planet was much stronger.
The shores of the land were
battered by the largest tidal
waves the world has ever known.
A thousand times greater
than they are today.
The infant Earth was
no place for us then.
The atmosphere was mostly carbon
dioxide, methane, and ammonia,
a toxic environment
for our kind of life.
We don't know what the
climate was like back then,
but scientists
reason that the thick,
hazy atmosphere trapped
the heat of the Earth and
made it scorching hot.
Another kind of life, tiny
creatures that could shrug off
the methane and eat carbon
dioxide and sunlight for breakfast,
found a way to make
a living in the ocean.
And those scrappy
little cyanobacteria,
as they're known,
remade the whole planet.
By gobbling up
the carbon dioxide,
and giving off oxygen,
they turned the sky blue.
All that oxygen destroyed
the methane shroud
that enveloped our planet.
And it was cool.
Not as cool as it is now,
but more like a really hot
summer day year-round.
And then something
wonderful happened.
The atoms of oxygen that
the tiny creatures in the ocean
produced began to gather
high above the world in the sky.
And a new kind of
molecule was made.
Ozone.
It created an invisible
canopy against those rays of
the Sun that were lethal.
Now, for the first time,
life was free to leave the
oceans for the land.
And before long, life seized
these new opportunities.
A wild variety of shapes and
sizes evolved as adaptations
to these new habitats.
And there were ears
and noses and wings.
I'd like you to meet
a fellow Earthling,
a very distant
relative of yours.
You've only been here a day,
but beetles have been
here for 300 million years.
And the changes they've
seen on this world
Our kind has only been here for
a fraction of that amount of time,
11:00 on New Year's
Eve of the cosmic year.
That's when our ancestors
stood up for the first time.
We call them Homo
Erectus for that reason.
They were no longer forced to
stare at the mud beneath their feet.
Now, they could look
up and see the stars,
and their hands were
free to change the world.
They began to move
around, to explore,
daring to risk everything
to get to unknown places.
They were brave.
And their blood
runs in your veins.
Some of them explored
the vast continent of Africa.
Others ranged north,
taking a left turn into Europe.
There is evidence that they
would later evolve into the
lost people we
call Neanderthals.
We have no idea what
they called themselves,
but we named them after
the place in Germany where
we first discovered
their ancient remains.
Another even more
mysterious branch of our family
took a right turn into Asia.
And they evolved into
people we call the Denisovans.
But you and I,
and all our other human
brothers and sisters,
were mainly descended
from the people who stayed in
Africa for another
million and a half years.
Sure, most of us have a little blood
from the other branches of the family,
but we are mostly
the children of Africa.
To see how our kind
spread out around the planet,
we have to go even
closer to midnight.
11:55.
Or about 150,000 years ago.
It is now a minute
and a half to midnight.
Until about 40,000 years ago,
our Neanderthal relatives
lived very much as we did.
They had bigger
brains than we do,
and were brawnier,
but they did many of the things
that we think of as being human.
Most of us still carry some tiny
portion of their genes inside us.
But there are no more
living Neanderthals today.
Nor are there any
of our other cousins,
the Denisovans.
When this happens, when
a whole species vanishes
we call it extinction.
It's the end of a road that
began four billion years ago
with the origin of life.
We don't know why they died out.
We do know that they never
ranged beyond the ocean
coastlines of their environment.
Maybe our hominid cousins
were just a bit more contented,
less anxious and more
at peace than we are.
Maybe it's a restlessness
that prods us humans to
choose the unknown.
Some powerful force
moved our ancestors to daring
feats of courage.
They crossed great oceans with
no idea of what lay on the other side,
carrying our people to
every continent on Earth.
And even to the Moon.
By the last second
of the cosmic year,
there was no place on Earth
that we had left untouched.
We became the first species
to remake the planet since the
one-celled cyanobacteria
did billions of years ago.
To change the oceans, the
land and the atmosphere.
And these changes have
led to a new mass extinction.
The scientific community
has looked at the evidence,
and decided our age
needs a new name.
The Anthropocene.
"Anthropo" from
the Greek word for
"Human" and "Cene" the
Greek word for "Recent."
It reflects our global impact
on the environment and
the life it sustains.
There's disagreement
about when it began,
and nobody knows
how it will turn out.
Happy New Year, little one.
Welcome to the Anthropocene.
TYSON: I see a great
future for you, little one.
But a shadow hangs over it.
We're not exactly sure
when the darkening began.
When did we become a force
of nature, altering the skies,
the seas and the
land of the planet?
When did the age of
the Anthropocene begin?
Some would say that it
started in places like this one,
more than 10,000 years ago.
Did our ancestors paint
these images of mammoths and
saber-tooth tigers and giant
sloths to somehow keep their
memory alive after
slaughtering the last of them?
Human-caused
extinction is nothing new.
But we can't really
blame our ancestors.
How could they know
that this or that kill meant
the end of an entire species?
I wonder, maybe the
Anthropocene started with the
first seed that was
planted in the ground,
and the agricultural
revolution that followed.
Before that time, the world
had twice as many trees to
convert the Earth's
carbon dioxide into oxygen.
With the invention
of agriculture,
our ancestors stopped
wandering to settle down into
farms and cities.
This is Çatalhöyük.
It was one of
the earliest cities.
This is how it looked
about 9,000 years ago.
The great move indoors
changed our relationship to nature.
Those hearths, those
fires that warmed the small
dwellings of our ancestors
were they the beginning?
The smoke from those
small fires did little to
alter the atmosphere.
But over thousands of years,
our numbers grew exponentially,
until we were cranking
out enough carbon dioxide
into the atmosphere to
warm the whole world.
Did the Anthropocene begin with
the domestication of animals?
Cattle convert wild
grasses into methane,
another gas that
changes the climate.
It happens inside them when
they're digesting their meals.
But nobody would
figure this out until the
modern scientific era.
How could a few head
of cattle do any harm,
let alone change
Earth so radically?
Our ancestors wanted
to feed their families,
and make sure that the little
ones would not go hungry.
That they would live.
In China, around
4,000 years ago,
a world-changing
discovery was made.
There were rocks that you
could burn for fuel to drive
away the cold and the damp.
These rocks were actually the
carbon remains of plants and
trees that had died hundreds
of millions of years before,
and lay buried in the earth.
Was the discovery of coal the
beginning of the Anthropocene?
Coal became increasingly
important to power forges and
foundries and homes.
Or did the Anthropocene really
get going about 1,000 years later,
when people all over
Asia began to grow rice?
This ingenious technique,
which involves transplanting
seedlings into flooded paddies,
is called "Puddling."
There was no way for these
hardworking farmers to know
that this particular
method of growing rice,
like the cattle, would someday
produce tens of millions of
tons of methane per year.
The flooded soil loses
oxygen, and then tiny,
invisible creatures, microbes,
digest the plant matter
and produce methane.
The leaves of the rice plants release
more methane into the atmosphere.
These early farmers had
no way of seeing what was
happening on the
scale of the very small.
Again, they were just
trying to feed themselves
and each other.
There's all kinds of writing.
But this is how time writes.
If you know how to
read time's alphabet,
you can reconstruct events
in the great story of the planet.
The most dramatic passage
in this saga is not written in
the brightest colors,
but in pale white.
This pale white line is
kind of an epic poem.
It tells the saga of
the death of titans,
all over the planet.
This layer of an otherwise
rare metal called iridium,
signifies the end of the
Cretaceous chapter some
66 million years ago.
This is when dinosaurs,
and three quarters of all the
plants and animals
became extinct.
There's a custom
among geologists.
If you find a layer in
the earth that indicates
the boundary of the first or
last time that the fossils of
any species can be found,
you mark it with
a "golden spike."
You drive it into the
rock with a hammer.
If we are living in
the Anthropocene,
the age of human-
caused extinction,
what wall do we drive
our golden spike into?
It's in me, little one.
When I was brand new,
just like you, only a day old,
there were two great
superpowers fighting
over the planet.
They were both willing to
destroy everything to assert
their dominance.
On the very day I was born,
both nations exploded nuclear
weapons in the atmosphere
just to show how strong they were.
And those were only a few
of the thousands that were
detonated over a
period of decades.
The bombs gave off strontium 90,
an atom made unstable
by its excess nuclear energy.
It's called a
radioactive isotope.
It polluted mother's
milk all over the planet.
Mothers nursing babies like
you refused to live with this horror.
They joined together to protest
until a treaty was signed in 1963.
I, and my whole generation,
carry an excess of
another radioactive isotope
in the tissues of our bodies.
It's called carbon 14.
So if I ever lose my mind,
or forget how old I am,
the echoes of those
nuclear explosions on the day
of my birth would
tell you my age.
Does this "golden spike"
inside me signify the beginning
of the Anthropocene?
Is that when it began?
The atmospheric testing ended,
but we just kept on
trashing our home.
All the while knowing that
the day would come when
it would all fall down.
What good is it to know
of a danger if you don't do
anything about it?
Maybe it's better not to know.
Knowing can be a curse.
The stories that live the longest are
those that never were,
and always will be: myths.
Apollo, the
ancient god of light,
was always on the prowl
for attractive humans.
One day, while strolling
the bustling streets of Troy,
a rival city of the
Ancient Greeks,
he spied Cassandra, the
smartest and most beautiful of
the daughters of King Priam.
Apollo fell madly
in love with her.
Apollo usually got his way,
and he was shocked when
Cassandra rejected him.
How could he win her heart?
She lacked for nothing.
And she was happy.
But Apollo was not
so easily dissuaded.
And so he made her
an irresistible offer.
He would grant her
the gift of prophecy,
the ability to see the future.
Cassandra was thrilled.
Knowing what would happen
before anyone else would make
her all-powerful.
But then, Apollo explained to
her what he expected in return.
She would have to
submit to him as his lover.
This was too high a
price for Cassandra.
Apollo's rage took the form
of a cruel and ingenious curse.
He granted Cassandra the
ability to foresee the future,
but condemned her to be ignored.
The Trojans
thought she was nuts.
They contemptuously
referred to her as the
"Lady of Many Sorrows."
Today she would be
dismissed as a prophet of
gloom and doom.
Cassandra saw nothing but
trouble when her brother, Paris,
decided to take
a trip to Sparta.
She alone knew that
when he got there,
he would fall in love
with the King's wife,
a beauty named Helen,
whom he would abduct.
This would bring ruin to Troy.
But no one paid any attention.
This was a time of
peace and prosperity.
There was no clear
and present danger.
The King wouldn't
listen to his daughter.
No one would.
When Paris brought Helen home,
the people of Troy
celebrated her arrival.
Cassandra was so desperate
to prevent the coming
disaster that she
attacked Helen.
Cassandra knew that the
Greeks would seek revenge
against the Trojans, and
that they would be victorious.
She foretold the defeat
of her father's army,
and the sacking of
Troy by the Greeks.
And the Greeks did come,
just as Cassandra
knew they would.
But even after years of
warfare, Troy still stood.
When the Greeks retreated,
boarding their ships and
sailing out of the harbor,
there must have been a
sigh of relief among the few
who wondered if there was
something to Cassandra's
dire predictions.
But what about that
enormous wooden horse?
A Trojan platoon was
sent to investigate.
They found a
single Greek soldier.
A man named Sinon.
The Trojans asked
Sinon, "What's going on?"
He told them that a King of
the Greeks had wanted to offer
him up as a human sacrifice.
So he'd stayed
hidden until his brothers
departed for home.
And that colossal wooden horse?
Sinon told them that it was an
offering for the goddess Athena.
How wonderful,
the Trojans thought.
The horse was the
ancient symbol of their city.
Why not move it inside the
gates and keep it as a trophy?
Sinon laughed, and told them that
the Greeks had said it was way too big
and heavy for weaklings
like the Trojans to move.
"Let them stare at it all
day and be ashamed about
how feeble they are."
(horn)
(speaking in native languge)
(cheering)
♪♪
TYSON: The Trojans were
terrified that Cassandra's
attempt at arson would
enrage the goddess Athena,
and bring her wrath
down upon the city.
♪♪
Once the invaders
gave the signal,
the ships of the Greek navy
that had been waiting out of
sight offshore commenced
their attack on Troy.
(screams)
♪♪
Apollo had had his fun.
Cassandra's grim prophecies
had gone unheeded,
and now it was
too late for Troy.
For Cassandra,
knowing was a curse.
But it can also be the
greatest of blessings.
Let me tell you another story.
Once upon a time, there
were no refrigerators.
♪♪
TYSON: It used to be hard to keep
food from spoiling in the summertime.
There was a person
called the "iceman."
He would come to your house
and sell you a big block of ice.
You'd keep it in something
called an "icebox" to preserve
the kinds of food
that spoil quickly.
But that was a drag
because the ice kept melting.
It would drip all
over the floor.
So somebody thought up
another way to keep food cold.
It was a gas powered system that used
ammonia or sulfur dioxide as a coolant.
No more lugging blocks of ice.
What could be bad about that?
The chemicals were
not only poisonous,
they smelled terrible
and there were leaks.
A substitute coolant
was badly needed.
One that would circulate
inside the refrigerator,
but would not poison anyone
if the refrigerator leaked,
or pose a danger if it
was sent to the junkyard.
Something that
wouldn't make you sick,
wouldn't burn your
eyes, or attract bugs,
or even bother the cat.
But in all of nature, no such
material seemed to exist.
So chemists in the
United States invented a
class of molecules.
Little collections of even
tinier things called atoms,
that had never
existed on Earth before.
They called them
chlorofluorocarbons,
or CFCs, because they were
made up of one or more carbon
atoms and some chlorine
and/or fluorine atoms.
These new molecules
were wildly successful,
far exceeding the
expectations of their inventors.
(overlapping chatter)
Not only did CFCs become
the chief coolant in refrigerators,
but also in air conditioners.
There were so many things
you could do with CFCs.
People used them to propel great
fluffy mounds of shaving cream.
And to protect your
hair from wind and rain.
It was also the propellant
that made fire extinguishers
and spray paint
cans so much fun.
It was good for foam insulation,
industrial solvents
and cleansing agents.
The most famous brand name
of these chemicals was Freon,
a trademark of DuPont.
It was used for decades and no
harm ever seemed to come from it.
Safe as safe could
be, everyone figured.
Until, in the early 1970s, two
atmospheric chemists at the
University of California, Irvine
were studying
Earth's atmosphere.
Mario Molina was a
Mexican immigrant,
a young laser chemist.
Sherwood Rowland
was a chemical kineticist,
someone who studied
the motions of molecules
and gases under
varying conditions.
He was from a
small town in Ohio.
Molina wanted to
grow as a scientist.
He was looking for a project
that would take him as far
from his previous research
experience as possible.
He wondered.
What happens to those
Freon molecules when they
leak out of the air conditioner?
This was a time when the
Apollo astronauts were still
making regularly
scheduled trips to the Moon.
And NASA was contemplating
weekly launches of
a space shuttle.
Would all that burning rocket fuel
pose a danger to the stratosphere,
that place where Earth's atmosphere
meets the blackness of space?
And this is how science
works a lot of the time.
You set out to
solve one problem,
and you happen on
a completely different,
unexpected phenomenon.
Those wonderfully
inert, "harmless" CFCs,
the magic molecules of
shaving cream and hair spray,
didn't simply vanish when
we were done with them.
They had an afterlife
at the edge of space,
where they accumulated
in the trillions.
They were silently congregating
high above the Earth,
and they were up to no good.
Molina and Rowland were
alarmed to discover that the
CFCs had thinned the
protective layer that shielded
us from the Sun's
harmful ultraviolet radiation.
And it was getting
worse all the time.
When UV light hits
a CFC molecule,
it strips away the
chlorine atoms.
Once that happens, the
chlorine atoms start devouring
the precious ozone molecules.
It wasn't until our planet
developed an ozone layer,
about two and a
half billion years ago,
that it was safe for life to
leave the ocean for the land.
A single chlorine atom can
destroy 100,000 ozone molecules.
CFCs were in everything,
and the manufacturers couldn't
imagine a world without it.
The corporate response
to this danger was that the
science hadn't been settled.
People had a hard time
believing that we had become
powerful enough as a species
to endanger life on the planet.
They looked for non-human
causes for the loss of the
ozone in the sky.
One Reagan administration
official suggested that
everyone just wear more sunblock
and put on a hat and sunglasses.
But the scientists pointed
out that the plankton,
those tiny plants at the
base of the global food chain,
and the larger plants,
were unlikely to do so.
Molina and Rowland tirelessly
worked to warn the world.
ROWLAND: What's the use
of having developed a science
well enough to
make predictions if,
in the end, all we're willing
to do is stand around and wait
for them to come true?
TYSON: Rowland and
Cassandra would've had a lot
to talk about.
But then something
amazing happened.
There was a global outcry.
People all over the
world got involved.
In the 1960s, the women of
the world demanded an end to
atmospheric nuclear testing
because they didn't want to
nurse their babies
with poisoned milk.
Then, in the '80s, consumers
demanded that the corporations
stop manufacturing CFCs.
And you know what, little one?
The governments listened.
CFCs were banned
in 197 countries.
That's just about as many
countries as there are on this planet.
And that's why this is
one danger you can cross
off your worry list.
The ozone layer has been
getting thicker ever since.
But what would've happened
if Rowland and Molina
hadn't been curious
about the stratosphere,
or if their warnings had been
ignored as Cassandra's were?
By the time of
your 40th birthday,
the ozone would have
been all but gone from
the entire planet.
You would never have been
able to take your own little ones
out to bask in the sunshine.
The food crops would
have completely failed.
The herbivores,
those who live off them,
would have died out.
The carnivores would subsist
on their corpses for a while,
but ultimately they,
too, would be doomed.
If we continue to
safeguard the ozone layer,
it will be completely
mended by your 50th birthday.
I may not get to see it,
but I have imagined
what it might be like.
TYSON: One last
story, little one.
It's about another person
who had the power to
foresee the future.
His story remains unknown
outside the scientific community.
But even Apollo would've
envied his power of prophecy.
He foretold an epic tale
of things to come with
astonishing accuracy.
And every one of us,
including you, are in his debt.
He was born in a rural
part of Japan named Ehime,
which means "Lovely Princess."
A place of unspoiled
natural beauty.
But he spent much of his
childhood buried beneath the
surface of the earth.
The cruelest war the world
had ever seen had forced the boy
and the people of his small
town to hide in an underground
bomb shelter.
At first, Syukuro Manabe,
or "Suki," wanted to be a doctor,
like his father and grandfather.
He discovered physics
and became enchanted by it,
but didn't think he
could do the math.
His grades were poor,
until he began to concentrate
on the questions that
interested him most.
Why is the atmosphere and
climate of Earth the way that it is?
He wondered why Earth
maintained the same average
global temperature
year after year.
What was keeping the
planetary thermostat set at that
particular temperature?
Was it possible to take all the
variables of the planet's climate
its atmospheric pressure,
cloud cover, humidity,
surface conditions,
ocean and wind currents;
and create a climate
model for the planet?
One that had the
power of prophecy?
Now remember, this was
before climatologists in Japan
had any access to computers.
He did these brain-numbing
calculations by hand.
In 1958, he was invited to
immigrate to the United States
by the US Weather Service.
Five years later, Manabe
was given access to
one of the first
"super computers."
When the great volume of
data about Earth's climate
crashed the entire
system, he was mortified.
It took him another four
years to assemble the evidence
for a bold and
tragic prediction.
There are broken branches
on the four-billion-year-old
tree of life.
And this is their monument.
Each hallway memorializes
the mass extinctions that
were so widespread that
life itself came close to dying.
The first five catastrophes
happened a long time
before we got here.
But the sixth is now,
and it has our name on it.
(growl)
(wind)
Sometimes prophecy comes as a
cry from the heart of a Trojan princess,
but it can also be the
dry-as-dust title of
a scientific paper.
Thermal Equilibrium of the
Atmosphere with a Given Distribution
of Relative Humidity.
Doesn't sound like,
"The sky is falling,
the sky is falling!"
But that's what it said.
Maybe this is where we
should place our golden spike.
Manabe and his colleague,
Richard Wetherald,
predicted how the temperature
of the planet would change as
a function of the increased
greenhouse gases humans pumped
into the atmosphere.
The scientists foresaw
precisely how the looming
catastrophe would unfold.
They saw far.
Into our own time, and beyond.
Some people still claim
the science is unsettled,
but if that's so, how was
it possible for Manabe and
Wetherald to correctly
predict the rise in Earth's
temperature across
more than 50 years?
And if it wasn't caused by us,
where was all that carbon
dioxide coming from?
The larger community of
climate scientists predicted
heightened flooding
of coastal cities, check.
The mass death of coral
reefs by ocean warming, check.
The increase in intensity of
catastrophic storms, check.
Lethal heat waves,
droughts and runaway wildfires of
unprecedented magnitude, check.
The scientists warned us.
What about your future,
your life, little one?
Your first day of kindergarten
was postponed until the
thermometer dropped below
the lethal temperature level.
When the wildfires came,
your family was forced to flee with
nothing from your childhood home.
Water was the
champagne at your wedding.
(wind)
(distant cries)
This doesn't have to be.
It's not too late.
There's another hallway,
another future, we can still have.
I promise to get you
there. We'll find a way.