All language subtitles for Human_Universe-S01E04-Unlocking_Space_and_Time.en

BRIAN COX: Every day in every town,
there's a moment...

(BABY COOING)

when for the first time,
we stare into the eyes of mum and dad

and are welcomed
into the arms of the universe.

Every human life has to start somewhere,

a place in space and time,
and I started here

on March the 3rd, 1968,
in the Royal Oldham Hospital.

In 1971, we moved here
to the family home in Chadderton.

It's only about a mile away
from the hospital.

I stayed here for the next 18 years.

In 1979, my world expanded a bit

because I came up the hill
to this school,

Hulme Grammar School.

This was my form room, 3Y,

and that was the end of the universe

because the girls' school
was through there.

And it wasn't long
before I began to wonder

how my world fitted
into the wider cosmos.

My granddad used to tell me
how he walked up onto this hill

in the summer of 1927,

to see a total solar eclipse.

And because of that story
I always wanted to see one.

And I finally got to do it,
80 years later.

And it was a very powerful experience,

I didn't know what I'd think.

He always spoke of the sky going dark
and everything going quiet

and the birds stopping singing.

What I felt was that
I was on a ball of rock.

I got a very powerful sense
that I was on this rocky planet,

orbiting in the blackness of space
around a star.

That understanding of where we are

is the culmination of 400-year journey
of scientific discovery.

This is the story of how we are
measuring with increasing precision,

our place in space and time,

how we've discovered
that we are an infinitesimal spec

in a possibly infinite universe.

And in doing so,
just how valuable we are.

As far as we know,
we humans are unique in the universe.

The only creatures
that have developed the ability

to ask deep questions about the cosmos.

This curiosity has led us
to a profound change in perspective.

From believing we were the most
important creatures in all creation,

we have uncovered
humanity's true place in the cosmos...

And glimpsed our earliest origins.

This is the fortified town
of Ait Ben Haddou.

It was built in the 17th century

on the trade route that winds
it's way north across the High Atlas

and into the markets of Marrakesh.

The indigenous Berber people
who built this place

have been in this part of North Africa
for well over 10,000 years,

and they're mentioned
in ancient Egyptian texts and in Greek.

Both Herodotus and Cicero
talk of these people

who worship the sun and the moon.

In fact, they tell a story
of how they cut off the ears of goats,

and threw them over their houses
in honor of the moon god.

And the skies are so crystal clear
that you can see why they did it.

Well, not the goat thing, but worshipped
those celestial objects in the sky.

High above the village,

the summit affords
an unobstructed view of the heavens.

The perfect vantage point from which
to ponder your place in the universe.

For all of history,
or at least I imagine,

for as long as people
have considered such things,

the Earth has been thought of
as being motionless,

at the center of the universe.

And when you think about it,
that's obvious.

It doesn't feel like we're moving.

And the ground feels solid
beneath our feet,

the proverbial mountains
move for no one,

and the sun, moon, and stars
arc across the sky.

The Earth is motionless at the center

and the universe rotates around it.

Watching the night sky,

it's natural to think
that the stars move around us.

And so for thousands of years,

this geocentric view of the universe
was never questioned.

And it's not just
the motion of the stars,

Aristotle the ancient Greek philosophers
thought about these things in detail.

They noticed that when you drop things,

they always fall towards
the center of the Earth.

So, therefore, there must be
something special about the Earth,

it must be the center of the universe.

These arguments are so persuasive

that it was millennia
before they were overturned.

It was here in Venice that our demotion
from the center of the universe began.

Venice was an independent city-state
for well over 1,000 years,

and by the 15th century,
it was the richest city in Europe.

You see that legacy everywhere,

buildings are spectacular.

You can only imagine what
it must have been like in its heyday.

And that pre-eminence,
put it at the center

of arguably
the greatest intellectual revolution

in the history of human civilization,
the Renaissance.

The Renaissance was a period
when the rebirth of art and science

transformed how we saw the world.

This is the Scuola Grande Di San Rocco

and everywhere you look,
there is masterpiece after masterpiece

from one of the greatest artists
of the Italian Renaissance, Tintoretto.

It took him over 20 years,

beginning in the 1560s,
to complete this building.

And it's breath-taking.

We see scenes
from the Old Testament on the walls,

scenes from the New Testament.

And what's striking, apart from
the obvious skill of the painter,

is the realism
and there, the Last Supper.

You could almost walk
into that painting.

You could walk across
that checkered floor,

up the stairs, turn right and out
through that illuminated doorway.

In the art
of the medieval period and before,

you don't see
this depiction of real space,

the paintings are flat.

From the 14th century,

with the rediscovery
of the geometry of the Greeks,

then you see
a genuine intellectual shift.

You see the desire
to paint the world as it really is.

You see paintings
with perspective and depth.

That was a change in perspective.

(BELL TOLLING)

And we got our first hints of
our planet's true place in the cosmos,

when this desire
to see things as they are

was combined with the city's
most valuable commodity.

(SPEAKING ITALIAN)

COX: During the Renaissance,

these craftsmen
were so valuable to Venice,

that they were barred from
leaving the city on pain of death.

Murano glass was so prized

because it's clarity allowed it
to be fashioned into optics,

into mirrors and lenses.

And it was precisely that property

that caught the eye of one
of the periods most renowned figures,

Galileo Galilei.

Now, in 1609,
Galileo came here to Venice

to commission lenses
for his new telescope.

This was the world center
of glass production

and he immediately
put that telescope to good use

by turning it towards the moon
and sketching what he saw.

In the 1600s,

most people thought that anything
in the heavens was perfect,

perfectly round, perfectly smooth,

but Galileo depicted the lunar surface
as we know it to be today,

the sunlight bouncing off mountains,
disappearing into valleys,

its shaded rims of craters.

Galileo didn't just observe the moon
with his telescope,

he turned it to the planets.

And also in 1610,

he made this series of sketches of Venus

and he noticed that different times
of the year,

Venus can appear
as a full circle in the sky,

or as a slim crescent
and is everything in-between.

When Venus is on the other side
of the sun from the Earth,

we see the whole planet.

But as it moves around in its orbit,

less and less sunlight is seen
to strike its surface

until it crosses the sun in silhouette.

The only credible explanation
to these phases of Venus,

is that Venus is a planet,

it's orbiting the sun
inside the orbit of the Earth

which is also orbiting the sun.

So, this is the first confirmation
of a sun-centered solar system.

Galileo had seen evidence
that the sun, not the Earth,

was the center of the solar system...

And began our scientific exploration
of the universe in earnest.

In the last 50 years,

we've done more
than simply look out from Earth.

We've sent unmanned space craft
to every corner of the solar system.

No, no, no, no.

- (HORNS HONKING)
- Tram.

Many not much bigger and not much
more advanced than this car.

Oops. Sorry.

It's a beautiful piece of engineering,
but it's essentially got no brakes.

We sent Mariner 10
and a messenger to Mercury,

the closest planet to the sun.

It's got no acceleration.

I don't know what these sticks do here.

Forty-three missions to Venus.

And 51 to Mars.

Hey-hey.

But only a handful have made it into
the solar system's outer most reaches.

In 1977, a chance alignment of
the planets, meant that it was possible,

at least in principle,

to launch a spacecraft
to all four of the outer gas giants.

So, NASA launched two spacecraft,
Voyagers 7 and 2.

And just 18 months later, they reached
the largest planet in the solar system,

aptly named after
the Roman king of the gods, Jupiter.

They explored Saturn,

before separating,
with Voyager 2 going on to visit Uranus.

And then in 1989,
after traveling for 12 years,

it reached Neptune,

the most distant planet
in the solar system.

But perhaps the most dramatic
change in perspective

came on the 21st of December, 1968...

When we left the Earth for ourselves
and set out for another world.

BELL ANDERS: When you're up
flying on a beautiful day,

you're certainly free like a bird.

And I just enjoy the scenery
and the solitude of it.

I've probably got
over 13,000 hours in the air.

But as a fighter pilot,
one of the things I pride myself in

is more landings than I have hours.

COX: Of all the flights
Major General Bill Anders has taken,

he'll be remembered for the one he made
when he was just 35.

MAN: (ON VIDEO) In the eighth year
of man flight into space,

the National Aeronautic
and Space Administration

prepared men and equipment for the most
advanced manned mission to date.

COX: Together with Frank Barman
and Jim Lovell,

Bill climbed aboard the most
powerful machine ever built by man.

(ROCKETS IGNITING)

ANDERS: When the rocket ignited
the giant 5F1 engines,

putting out a total of seven and a half
million pounds of thrust,

the racket was unbelievable.

MISSION CONTROL: We have lift off,
lift off at 7.57 a.m.,

Eastern Standard Time.

ANDERS: The sideways forces
as those rockets gimballed,

to try to keep us pointed straight up,

threw us around the spacecraft.

If we hadn't been strapped in,
we'd be bouncing of the walls.

Within about 30 seconds to a minute,

we flew out of the noise
and echo from the Earth

and we knew we were on our way.

GROUND CONTROL: Apollo 8,
Houston, you're looking good.

ASTRONAUT: (ON RADIO) This is Apollo 8.

GROUND CONTROL: We hear you
loud and clear, Apollo 8.

ASTRONAUT: (ON RADIO) Okay,
the first stage was very smooth

and this one is smoother.

COX: The three astronauts had begun
the longest human journey

ever attempted.

ASTRONAUT: I can see the entire
Earth now out of the center window.

I can see Florida, Cuba,
Central America...

COX: Over 68 hours and 57 minutes,

they traveled across
380,000 kilometers of empty space.

Until suddenly, their tiny craft
was plunged into darkness.

ANDERS: The stars just exploded.
I mean, there were...

Every star you ever thought about
was visible

to the degree that it was very difficult
to pick out constellations.

And yet, as I look back over
my shoulder, the stars suddenly stopped.

And there was this big black hole,

and that was the moon.

And I must say, that got
the hair on the back of my neck

standing up a little bit.

COX: On Christmas Eve, 7968,
Apollo 8 entered lunar orbit.

ANDERS: It was just one crater
on top of another crater

and no matter how close you looked,

you were gonna find smaller and smaller
craters on top of the big ones.

It looked like a battle field,
it was totally beat up.

COX: It was as they emerged

from behind the desolate lunar surface
for the third time,

that our perception
of the Earth changed forever.

ANDERS: But when we finally
turned around and were going forward

like a car driving on down the highway,

we saw for the first time,
the Earth come up on the lunar horizon.

I set the range at infinity,
pointed it at the Earth,

and just started clicking away,
changing the F-stop with every click.

ANDERS: The photograph
was the shotgun approach,

you figure one of them
is gonna hit, and indeed it did.

COX: The photograph Anders took
is known as Earthrise.

One of the iconic images of our time.

ANDERS: After the flight,
I've often been asked

what I thought was
the most significant part of Apollo 8,

its biggest contribution.

And I've often said, our mission
really was to explore the moon,

but our accomplishment was
that we discovered the Earth.

COX: It was only by looking back
at our planet from afar

that we felt just how small
and delicate a part of the universe

our fragile world really is.

ANDERS: Well, I look up and realize
that the moon is a long way off,

240,000 miles,
and sometimes it's hard to imagine

that we actually zipped
all the way up there

and around it 11 times
and back in this day and age.

COX: Hundreds of years of exploration

have revealed our planet
to be just one of eight

in orbit around a star we call the sun.

But understanding
our place in the solar system

is only the first step
in finding our place in the universe.

Because far beyond anywhere
we can visit, lie the stars.

Until recently, there was no way
of knowing how distant the stars are.

And so we had no idea
of our star's true place in the heavens.

(cow MOOING)

MAN: I've been roping
since I was a little kid.

Now, the older I get,
the more I like roping,

it's very important part
of the cowboy lifestyle.

The most important skill
when you're roping

is accuracy and judging the distance.

You've gotta be a real good judge
of where the steer is gonna be

when you throw your rope.

COX: Because our eyes
are a few inches apart,

each one captures a slightly different
view of the world.

And comparing the differences
between the two images

is one of the ways
the brain judges distance.

It's a phenomenon known as parallax.

And remarkably,
you can use the same effect

to measure the distance to the stars.

Now, the parallax shift of a star
in the sky from one eye to the other

is of course imperceptibly small,

but if you could arrange for your head

to be, let's say,
180 million miles in diameter,

then the parallax shift
would be measurable and you can do that.

Here are two pictures
of a double star system called 61 Cygni

taken in May and November.

That's when the Earth is on
one side of the sun and the other.

There is your 180 million miles.

And as you can see,

the shift is small but noticeable.

COX: Using parallax, 61 Cygni

was found to be
104,000 billion kilometers from Earth.

But this technique only works
for our nearest stellar neighbors.

The vast majority of stars
are so much further away

that they exhibit no perceptible
parallax shift at all.

So to go beyond our local
stellar neighborhood,

a new technique was required.

And it involved measuring
the brightness of the stars themselves.

If you want to use
the brightness of a star

as seen from the Earth's surface
to measure its distance,

then you have to know
how bright the star actually is.

And the first person
to work out how to do that

was one of the great unsung heroes
in the history of astronomy,

Henrietta Leavitt.

Leavitt was cataloging the brightness
of stars from photographs

and she became interested
in a particular kind of star

known as a variable star
which changes its brightness over time.

So it goes dimmer and brighter,
dimmer and brighter,

over a period of days
or weeks or even months.

She took a special interest in a class
of variable stars called Cepheid.

Now, what Leavitt noticed was
that there is a simple relationship

between the actual brightness
of the Cepheid variable

and the rate of change
of that brightness, its period.

She noticed that
for the dimmer Cepheid variables

the rate of change in brightness
is very fast,

whereas for the brightest
of the Cepheid's

the rate of change is slow.

So, that means that if you can
determine the distance

of just one Cepheid variable
by parallax,

then you know
the distance to all of them

just by measuring the rate of change
of the brightness in the sky.

Now, within a year of the publication
of the paper in 1912,

the size of the Milky Way galaxy
had been measured

and shown to be
100,000 light years across,

with the sun not near the center,
but close to the edge.

The Milky Way is a disc of between
two and 400 billion stars

reaching out in giant spiral arms.

The sun and the solar system sit within
the inner rim of the Orion Arm,

27,000 light-years
from the galactic center

which they orbit once
every 248 million years.

But as vast as the Milky Way is,

it wasn't long before we found
Cepheid variables

that were far more distant.

Our galaxy wasn't the only one.

MAN (OVER RADIO):
Five, four, three, two, one

and lift-off of space shuttle Discovery

with the Hubble Space Telescope,
our window on the universe.

COX: Only 400 years ago,

Galileo used simple glass lenses
to explore the solar system.

Today, we use advanced instruments
like the Hubble Space Telescope

to explore the universe.

MAN: (OVER RADIO)
Do you like this, Houston?

MAN 2: (OVER RADIO) Oh, it's not' bad.

COX: Hundreds of billions of galaxies
stretching out in every direction

to the edge of the observable universe
and 46 billion light-years away...

We've discovered that the universe
is far grander,

far more majestic than anyone suspected

when we first started exploring it
just a few centuries ago.

And we've discovered there are no
special places in the universe,

we are not at its center,

we just orbit around one
of a trillion suns,

which raises an obvious question,

where did all those stars come from?

(SPEAKING ARABIC)

(GOATS BLEATING)

COX: For 51 weeks a year,

the 88 households
of Souad's tiny village

make up her entire universe.

But this week will be different.

For a few days every year,
thousands of Berber tribespeople

from across the High Atlas
leave their isolated villages

to attend a festival of marriage

in the hope of finding a partner

and so beginning a new chapter
in their family history.

(SPEAKING ARABIC)

COX: Just as in Souad's family,
for as long as anyone can remember,

each generation of Berber
have returned to this place

to begin the next generation.

Today, we can trace
our origins much further back

than our immediate family tree,

back, in fact, further than the origin
of our species here in Africa,

back past the origin of life on Earth
and the formation of Earth itself,

back, in fact, to what appears
to be the beginning of time.

And that didn't require
a journey of exploration in a spaceship,

flying off into the unknown,

just required something
that we all possess,

the human imagination.

(KIDS LAUGHING)

COX: Scientists are often described
as being childlike,

and the archetypal example
is Albert Einstein.

And I think it means
thinking with simplicity...

(KIDS LAUGHING)

following threads carefully
and tenaciously, seeing where they lead,

following the implications
of a thought through

and asking the question
why, why, why, why?

It's having a mind uncluttered
by the adult affliction of common sense.

COX: Einstein would free
his mind of the everyday

and allow it to wonder
through the universe.

He imagined himself
riding on a beam of light.

And by wondering what he might see,

he transformed
our understanding of space and time.

But it was his re-imagining

of an experiment dreamt up
by Galileo in the 1500s

that laid the foundations
of modern cosmology.

Einstein called it
"The happiest thought of my life,"

which is in itself
an almost childlike sentence,

because following that thought through

ultimately led us to a theory
of the origin of the universe itself.

And there's a place where
you can see with your eyes

what Einstein saw in his mind.

This is NASA's Space Power Facility
near Cleveland, Ohio

and it is the world's
biggest vacuum chamber.

It's used to test spacecraft
in the conditions of outer space

and it does that by pumping out
the 30 tonnes of air in this chamber

until there are about two grams left.

This has kind of got
an eccentric construction,

which is part of its history.

It was built in the 1960s
as a nuclear test facility

to test nuclear propulsion systems.

And that meant that
they built it out of aluminum

to make the radiation
easier to deal with.

Aluminum is not the best thing,

the strongest material,
to build a vacuum chamber out of,

so they built outer concrete skin

which is part radiation shielding
and part an external pressure vessel,

so this thing can take the force
that's present on the outside

when it's pumped out
to the conditions of outer space.

Galileo's experiment was simple,

he took a heavy object and a light one

and dropped them at the same time
to see which fell fastest.

Now in this case
the feathers fell to the ground

at a slower rate than the bowling ball
because of air resistance.

So, in order to see
the true nature of gravity,

we have to remove the air.

(ALARM BLARING)

It takes 3 hours to pump out the 800, 000
cubic feet of air from the chamber.

Okay, we dropped 2 millitorr
in the last 30 minutes.

COX: But once it's complete
there's a near perfect vacuum inside.

MAN: 61-04, manual, 10 percent open.

Station one, go for drop.

PCB 30 dash one,
pressure set point at 240 psi.

We are go for drop.

Ten, nine, eight,

seven, six, five,

four, cameras on,

two, one, release.

- (LAUGHING)
- Exact. Exact.

- They came down exactly the same.
- Wow.

Oh, look, look, look.

- Holy mackerel.
- (LAUGHING)

Exactly the same.

- COX: Exactly the same.
- MAN: The feathers don't move, nothing.

Look at that, that's just brilliant.

COX: Isaac Newton would say
that the ball and the feather fall

because there's a force
pulling them down, gravity.

But Einstein imagined
the scene very differently.

The happiest thought
of his life was this...

The reason the bowling ball
and the feather fall together

is because they're not falling,

they're standing still,
there is no force acting on them at all.

He reasoned that
if you couldn't see the background,

there'd be no way of knowing
if the ball and the feathers

were being accelerated
towards the Earth.

So he concluded, they weren't.

Instead, Einstein proposed that
the force of gravity is an illusion.

Just as the surface
of the Earth isn't flat,

neither, he said,
was the fabric of space.

All objects, like stars and planets,

warp the space and time around them
to produce valleys.

And all objects,
like planets and bowling balls,

move across this curved landscape,

giving the appearance
of being diverted by a force.

Einstein called this theory
general relativity.

Esoteric and strange
as Einstein's theory of gravity seems,

it can be tested.

The Arecibo Observatory in Puerto Rico

has the largest dish of any telescope
anywhere in the world...

Enabling it to detect the faintest
radio waves from galaxies far, far away.

When we come back,
we should destroy the shield generator.

Using telescopes like this,

we witness some of the most violent
gravitational events in the cosmos.

The deaths of giant stars.

Entire suns devoured by black holes.

And here at Arecibo, they've studied

one of the most extreme systems
in the universe,

a binary pulsar,

and measured the stars' doomed orbits

as they spiral towards each other
to the last millimeter.

These measurements are so precise,

that using this telescope has found
that the radius of the orbits

is decreasing by 1.7 millimeters a day.

That number is precisely the number
calculated using Einstein's theory.

This is why I think that Einstein's
theory of general relativity is

arguably the greatest achievement
of the human intellect.

It is, as far as we can tell,
a precisely accurate description

of everything
we look at in the universe.

But Einstein soon realized
his equations could do far more.

They could rewrite
the most universal of human stories.

MAN: (OVER RADIO) In the beginning,
God created the heaven and the Earth.

And the Earth was without form and void

and darkness
was upon the face of the deep.

And the spirit of God
moved upon the face of the waters.

And God said, "Let there be light."

And there was light.

Einstein's equations allow you
to predict the shape of space time

given the distribution
of matter within it.

So, if you plug a spherical blob
of matter into his equations

the sun, let's say, and Einstein's
equations give you a solar system,

they allow you to understand
its past and to predict its future.

And shortly after
Einstein published the theory,

he had another happy thought.

He thought, "Well, if you can
do that for a solar system",

"why can't you do it for a universe?"

Think about that for a minute,

understand the past and predict
the future of the entire universe,

even Einstein thought he'd gone too far.

Because to do that, you need
to know how matter is distributed,

not just around a single star,

but across the whole cosmos.

The simplest thing you can do

is to assume that the universe
is the same everywhere,

there are no special places.

You assume a completely
uniform matter distribution.

And when you do that,

then Einstein's equations
predict something surprising.

They predict that the universe can't
be static and the universe is dynamic,

it's constantly changing.

Now, if you have an expanding universe

then that implies
that it was smaller in the past,

and ultimately it implies
that there was a beginning.

The Belgian priest and mathematician,
Georges Lemaitre,

who was one of the first to work
on these solutions, put it beautifully.

He said, "The universe must have had
a day without a yesterday."

Einstein's equations described
the evolution of the universe

all the way back
to its very first moments.

From its adulthood
with mature stars and galaxies...

Through adolescence...

To its childhood
and the formation of the first stars.

With every step back in time,
the fabric of space contracts

and the universe gets smaller...

Until 13.8 billion years ago,

it was born in the Big Bang.

And perhaps the ultimate triumph
of our exploration of the cosmos

is that in the last few years
we've taken a snap shot of the universe

in its infancy.

(MAN COUNTING DOWN IN FRENCH)

COX: On the 14th of May, 2009,

the Planck satellite was launched from
ESA's spaceport in French Guiana.

Its mission was to travel

one and a half million kilometers
into deep space

and there, far from any interference
from Earth,

to witness the birth of the cosmos.

For four years,
Plank scoured the heavens,

gathering the oldest light
in the universe,

light that began its journey to Earth

long before there were any humans
to witness it.

Light that is older than any galaxy,
more ancient than any star,

the cosmic microwave background.

This is the photograph of that light
that was released

380,000 years after the Big Bang

and has been journeying
through the cosmos ever since

for almost the entire history
of the universe.

It really is the afterglow
of the Big Bang.

(EXPLOSION)

In those first moments, the universe was
a fireball of hot opaque plasma.

But as it cooled,
the first atoms formed,

and the first light was free
to roam through the universe.

And then coded in minute temperature
differences in that light

is the story of our earliest origins.

Those tiny variations
in the temperature of this radiation

which correspond
to tiny fluctuations in density

in the universe
when it was only 380,000 years old

are vitally important,

because these are the seeds
of the galaxies.

Without these slight density variations,

there would have been nothing
for matter to coalesce around

and we wouldn't exist.

And that makes this, I think,

by far the most remarkable picture
of all time.

(RUMBLING)

So, this is our place in space and time,

15.8 billion years from the Big Bang...

27,000 light-years from
the center of the Milky Way galaxy...

On a rocky world
orbiting a yellow main sequence star.

Today, the 21st of June,

the Earth's northern hemisphere
is tilted towards the sun,

and here in Poland,
people gather to celebrate

the shortest night of the year.

(INDISTINCT CONVERSATIONS)

We've come a long way.

In only 500 years, we've journeyed
to the edge of our solar system

and photographed our whole world.

We've counted the galaxies.

We've captured the most ancient light
in the universe and measured its age.

And in doing so, we've discovered

that we are just one planet in orbit
around one star amongst billions,

inside one galaxy amongst trillions,

afloat in a possibly infinite sea
of space time.

COX: In finding our place
in the universe,

we've come to realize how small
and fragile a part of it we are.

But it's been the most glorious ascent
into insignificance,

because our physical demotion
has been the inevitable consequence

of a daring intellectual climb,

from being the puppets of the gods
to that most rare and precious thing,

a scientific civilization, the only one
we know of anywhere in the universe

that's been able to comprehend
it's true place in nature.

That is our greatest achievement.