Where do we come from?
How did the universe begin?
Why is the universe the way it is?
Good morning.
Welcome to Gonville and Caius,
More commonly known as Caius College.
Caius College was founded in 1348
By Edmund Gonville.
Where are we going?
Now we come to the portrait
Of probably our most famous caiusan,
Professor Stephen Hawking, The world-famous cosmologist.
Like predecessor sir Isaac Newton before him,
He is lucasian professor of mathematics
For the university,
And his particular sphere Is research of the black hole
And the history of the universe,
Culminating in his book "The brief history of time,"
Which worldwide has sold Over 8 million copies.
Hawking: all of my life, I have been fascinated
By the big questions that face us,
And have tried to find Scientific answers to them.
Perhaps that's why I have Sold more books on physics
Than Madonna has on sex.
Now this is professor Hawking's study,
Which he will use when he's In residency in college.
He'll use this for his Tutorials or meetings
Or any private work he needs to do.
It is very much a personal Room with his books
And his portraits and pictures, So it's really a home from home
when they're in college.
He's got an inherited disease, motor neuron disease.
He can project his voice with a synthesizer
Which is attached to his wheelchair.
Hope you enjoyed your visit. Bye. Bye.
If, like me, you have Looked at the stars
And tried to make sense of what you see,
You too have started to wonder what makes the universe exist.
The questions are clear and deceptively simple,
But the answers have always seemed well beyond our reach
Until now.
Narrator: our view of the universe
Has long been shaped simply by what we could see.
For thousands of years, that meant we understood
Only what the naked eye could behold.
Now, new breakthroughs In science and technology
Are rapidly advancing our horizons.
We are witness to the very brink of time and space.
Hawking: I want you to share my excitement
At the discoveries, past and present,
Which have revolutionized the way we think.
From the big bang to black holes,
From dark matter to a possible big crunch,
Our image of the universe today
Is full of strange-sounding ideas
And remarkable truths.
The story of how we Arrived at this picture
Is a story of learning to understand what we see.
Narrator: with every century,
Our eyes on the universe have been opened a new.
Only 75 years ago,
At the Mount Wilson Observatory in California,
A young astronomer peered into a now-primitive telescope
And forever changed our understanding of the heavens.
His name -- Edwin Hubble.
We know, thanks to Hubble, that
Altogether within the limits
Of the observable universe
There's something like
100 billion trillion stars.
It's a lot of stars.
And we now know thanks to recent discoveries
-Very recent discoveries also
What we had believed But had no proof of,
And that is that many of those stars have planets.
So there are countless trillions of planets
In the observable universe.
Narrator: this was among Hubble's
Most striking contributions
Even as it was for his predecessors.
The more we learn about the universe,
The humbler the role We seem to play in it.
Jastrow: two-thirds of The stars and planets
And life, if it's there, in the universe
Are billions of years older than we are.
And if you ask what a billion years means
In the history of life, I must tell you
That a billion years ago
The highest form of life on the earth was a worm.
Three billion years ago,
The highest form of life on the earth were bacteria.
So we must ask ourselves,
We who are so proud of our accomplishments,
What is our place in the cosmic perspective of life
If most of those beings out there,
If they are there, stand in relationship to us
As we do to the worms on this planet?
And that is not meant to be a denigrating remark,
But only to suggest that humankind's greatest experiences
Still lie ahead of us.
Narrator: it was the sumerians and babylonians
Who first studied the workings of the heavens.
Tions laid the groundwork
For the ancient greeks who followed.
They could see the stars
And wonder about the sky and the heavens
But they had very little information indeed --
Just what their eyes could pick up.
They thought that everything they knew came out of the water.
Obviously water was a very important substance,
And so they gave water a sort of cosmic significance.
They thought that the heavens are made of many holes,
And these holes represented the stars,
And just behind they had this divine fire.
Narrator: the greeks had long explained what they saw
With myths and legends.
Now they began to use reason.
Cotsakis: they thought that they had to find
A more accurate way of expressing
Their views about the universe,
And that way dramatically turned out to be mathematics
Narrator: the science of logic was born,
And long-held assumptions were called into question.
Cotsakis: when you see from the distance
A boat coming,
You don't see the whole boat in the beginning,
But you gradually see the boat appearing
From the horizon as if it was raising up from the sea.
So in this way they questioned the view
That the earth was flat.
Narrator: proof that the earth was round
Would have to be persuasive.
A philosopher named Eratosthenes
Devised one of the first scientific experiments.
Identical objects on a flat earth
Should cast identical shadows.
So at the same time of day,
In two places miles apart,
He put this to the test.
It was a beautiful way that he discovered
Where he used two sticks.
He noticed that the rays coming from the sun
Produced different amounts of shade
In each of the two sticks.
Narrator: since each peg cast shadows of different lengths
The earth's surface had to be curved.
From the angle of the shadows, Eratosthenes could estimate
The earth's circumference at 25,000 miles --
Less than 100 miles off today's measurements.
To its first students,
The earth itself submitted to its laws.
Mathematics was the discipline
That endowed the greeks with ultimate truths.
Cotsakis: they realized
That they can use mathematics to develop
Theories and applications
To all sorts of different kinds of phenomena.
Hawking: but mathematically beautiful theories
Are not always supported by observation.
In the earliest days of astronomy,
The ancient greeks found the heavens
Less perfect than they had first imagined.
Looking at the skies more closely,
they began to see stars move
in a way which defined their logic.
If every night you go out
And you have a careful look seeing towards south,
after two or three days
if you watch again you'll see five stars.
And this is something unusual
in respect to the other stars of the sky
which don't change any position.
They look as moving from west towards the east.
Sometime they look staying still.
Then they begin to move from the east towards the west
Narrator: the greeks had identified
five heavenly bodies that neighbored us.
They dubbed them "Planetos" or "Wanderers."
They believed in a universe in perfect balance.
The planets, they were convinced,
were precise globes,
traveling in sublime circular orbits.
But observation said otherwise
It was the astronomer Ptolemy
Who tried to explain the discrepancy with math.
He made adjustments to the planets' orbits,
retracing their paths as circles within circles,
All neatly fitting within a sphere of fixed stars.
At the center of the universe --
The Earth.
Ptolemy lived over a century after the death of Christ.
The new christian church
was quick to seize upon a model of the universe
That imagined us, God's pride, at its center.
Papathanassiou: the cosmology of the church
is the cosmology of the Genesis,
and if something has the same ideas
as they are described In "Genesis," it's okay.
For those who could understand
the mathematics of Ptolemy's model,
well, it's a model which can foretell
the position of the planets
with an accuracy which is satisfying.
And on the other hand there is nothing
which can contradict the idea of the genesis.
3, 2, 1, zero,
Liftoff!
Hawking: today, the claims of the scriptures
are being put to the test
By experiments launched into the heavens.
Steady improvements in technology over the years
have enabled us to test our theories
about the universe.
But before such detailed
observational evidence was available,
belief in any theory was often
as much a matter of faith and conviction
Ptolemy's model of the universe
went virtually unchallenged for 1,500 years,
supported all the time by the church,
which was at that time the repository of learning
Lord, receive our gifts.
Let our offerings make us holy
And bring us salvation.
Narrator: Ptolemy's vision prevailed
of a universe that acknowledged our supremacy
of an earth that, after all,
did not seem to move.
And if simple experience weren't enough
to lend Ptolemy credence,
he had the support of the authorities as well
The catholic church, by and large,
through the centuries, say, from Ptolemy
For 1,000 years -- A bit more --
Was the educated world.
Ptolemy thought that it wasn't really sensible
to have anything but the earth as the center, not so much
for astronomical reasons, but because, after all,
if you're not used to it, it does seem incredible
that the earth can be moving
And Ptolemy catalogued
quite a few of the obvious reasons
which affront common sense
Like, why aren't we hurled off a rotating earth?
How could the birds fly if there was a constant gale blowing?
and so on.
So that, I think, weighed fairly heavily with Ptolemy.
Narrator: by the 16th century, Ptolemy's followers were faced
with increasingly contradictory observations
The church's teachings would soon enough be undone
by one of its own scholar-priests.
Sharratt: Nicholas Copernicus was a church man
Not just in the sense he was catholic,
but he actually held
a church office as a canon
of a cathedral.
He had a great admiration for Ptolemaic astronomy.
Lacked a certain elegance for Copernicus
He found he could better explain observations
if he made one staggering shift.
He put the sun,
not the earth, the center of the universe.
Hawking: it was a revolutionary moment for cosmology.
Copernicus had radically re-organized
the model of the universe which had lasted for centuries.
He began an irreversible process
that has downgraded us from the center of the universe
to the outer suburbs
of one among billions of galaxies.
Narrator: for the church, though,
Copernicus' model amounted to heresy.
God had put man on earth,
and the earth at the hub of his creation.
Copernicus died in 1543,
his life's work dismissed but not forgotten.
Some 60 years later,
Johannes Kepler, a german mathematician,
took up his work.
Sharratt: he broke with 2,000 years
of philosophical and astronomical tradition.
What Kepler finished up with was non-circular motion.
He realized that the planets
are actually traveling in elliptical orbits.
The great thing about Kepler's system
is he can do everything Copernicus did
, simply with the one clear curve of the ellipse
in a colossal achievement.
Narrator: at first, the church failed to comprehend
the dramatic change coming
but when Galileo Galilei, An italian scientist,
dared to publish
Copernicus' heretical idea
the Vatican took action.
Man: we are now at the top Floor of the villa Il Juliello
in the place where Galileo
spent his last 10, 15 years of life,
the most dramatic part of his life,
as a prisoner being condemned not to leave the house,
not to receive guests.
And that's why this was a place at the beginning very happy,
at the end, very sad for him
Isolation was torment for Galileo
but, in solitude, his studies came into sharp focus.
The only work he could perform
during the period in which he was prisoner
in his own house, was the completion
of the laws of motion.
Narrator: Kepler's model
had raised some boggling questions.
For day to follow night,
the earth would have to rotate at a thousand miles an hour.
Why, then, didn't we fall off?
Your first impression Everybody,
a kid for instance, 5 years old,
not yet going to school,
you ask him if the earth is in motion,
he will say no.
He will not have any idea, any possible idea.
This is what was the situation , not just for kids,
but for everybody time of Galileo.
Narrator: that the earth was moving,
Galileo had no doubt.
He realized we were unaware of its motion
simply because as it moved we moved with it.
But he could not explain what force
keeps us fixed to its surface.
[ Bells ring ]
As he studied the laws of motion,
Galileo longed for a clearer view of the firmament.
Galuzzi: at the end of 1609 he heard
that there were into the market
some funny objects which were a tube with some glasses,
were giving some funny performance.
This instrument
was coming from Holland
and was sold as a toy.
When Galileo took it, it began to be transformed
from a toy to an instrument.
He started to use
the magnification power of the telescope
to look at the skies.
This is a major step in his career
qnd also in the history of modern cosmology.
Narrator: this novelty trinket, remodeled as a scientific tool
was to revolutionize our vision of the heavens.
At once, Galileo was witness to worlds we had only imagined
According to the church,
they should have been perfect spheres
orbiting the earth.
They were not.
Galuzzi: the moon was not so polished
and so round as people believed,
but they were presented
valleys and mountains exactly as the earth.
And he moved afterwards to other bodies.
He started to observe Mercury, Mars --
But he was captured by Jupiter
He started to observe, seriously,
Jupiter in january 1610,
and his diary note is very touching.
It says, "I have discovered a funny body,
something like that which is circulating around Jupiter,"
7 january, if i remember correctly.
And the day after,
he was immediately at the sunset at the telescope
Narrator: struck with disbelief, he sketched what he saw.
Galuzzi: in a few days he became aware
that those moons as he called them were four,
and they were satellites because they were doing
rhythmic and cyclic performances around the body of Jupiter
Narrator: something orbiting Jupiter
could not be orbiting Earth.
The church's model of the Universe was shattered.
This was the decisive step why Galileo became convinced
so he started to publish
and started to produce work saying, be careful.
We cannot stay anymore with Ptolemy.
What the bible was saying in many times
about the position of the sun
and the motion of the sun around the Earth
was not tenable anymore.
Galileo entered a fight with the authorities.
The book of Copernicus was suspended
and sent to correction.
Galileo was called to Rome at the tribunal of inquisition
Finally he was condemned.
Narrator: threatened with death at the stake,
Galileo retracted his claims
He was sentenced to spend the rest of his life
under house arrest.
Galuzzi: it's the beginning of the conflict
between science and religion
science and theology,
and it's a tension which is going to be
many other episodes during the modern age.
Narrator: Galileo's voice could be stilled,
but his spirit could not.
The spark he lit caught fire and for those who followed
Observing the sky became a consuming quest.
To this day, we peer into space
with the same sense of wonder he felt.
Observing is almost mystical.
It's the act that really puts me in contact
with the rest of the universe.
I often think if somebody's looking back at me --
I wonder if their telescope is bigger than mine.
Narrator: today's telescopes depend in part
on refinements introduced
by a man born the year Galileo died --
Isaac Newton.
Hawking: I feel I have links To both Newton and Galileo.
I now hold the same professorship at Cambridge
That Newton once held,
And I was born 300 years to The day after Galileo died.
But at least
half a million other babies
were born that day.
Man: Isaac Newton
Was born here in this house in Woolsthorpe
on Christmas day, 1642.
Newton, by all accounts, was a very difficult man.
His father died
before he was born.
His mother
the rather rich rector in the neighboring village.
Newton was left here in Woolsthorpe
at the age of 3,
and was brought up for the next seven or eight years
by his grandmother.
So I think he probably had a sense of insecurity.
Narrator: the year was 1660.
The world of astronomy was filled with questions
and ripe for change.
Barbour : at Cambridge, more or less by chance,
he picked up about four or five books on mathematics,
and he set to work to read them.
Six months later he was making
important contributions to mathematics.
18 months later he was
the greatest mathematician alive.
It's just staggering.
He taught himself, just from four or five books
and it all came out of that.
Narrator: Newton didn't lack ambition.
He set his sights on tackling mysteries
Galileo had left unsolved.
He bettered his chances
by incorporating an internal mirror in the telescope,
doubling its power.
Barbour: the news of this telescope
was distributed around Europe,
and that's actually what made his name.
And later on, that design of telescope
turned out to be the best one of all
for studying the heavens,
so in that way he greatly advanced astronomy.
Newton had been at Cambridge for several years
when the plague forced him
To come back home here to Woolsthorpe.
And at the time he'd left Cambridge,
he was beginning to think about the laws of motion,
how things are moving,
and he had the idea that basically things
would essentially move in a straight line
if they were left on their own
He was beginning to think about the forces
that might be at work,
and one of the most obvious is the pull of gravity,
which is pulling an object towards the earth.
Narrator: Newton's discovery became the stuff of myth..
Remember the story of the apple falling from a tree?
I think it probably is true
that he did start thinking about these thing
from seeing apples fall,
but I'm absolutely certain he didn't have
the complete theory of universal gravitation
back here in the plague year
and the full working out came much later.
His idea of gravity --
and he called it universal gravity
because that is a very important thing --
Is that every single piece of matter in the universe
pulls every other piece
of matter in the universe towards it, and vice versa
The earth is billions of times more massive than the apple,
so basically the earth is moving
ever so slightly towards the apple,
but you just can't see that.
The motion of the apple is much more pronounced
than that of the Earth.
The importance of the apple is that it symbolizes the idea
that the laws of nature that are working on the Earth
are also working throughout the whole universe.
Narrator: Newton's crowning achievement
was to unite all that had preceded him.
He applied his theory of gravity
to the heavens Kepler described,
then united Galileo's laws with his own.
He described the path of the moon around the earth
then looked beyond.
Barbour: and that was enough to give Newton the hints
to then apply those same techniques of Galileo,
but now to the planets.
And that essentially was the whole of the universe.
Narrator: with one sweeping theory,
Newton had redefined the cosmos.
He had solved the mystery of what kept us on earth,
what kept the Earth moving what set the stars in motion
Even the church had to bow to the inevitable.
The Ptolemaic system
had surrendered to one word -- gravity.
Barbour: he was the first person
which manifestly worked.
And the title of his great book, the "Principia"
That real makes the point --
He described it as the mathematical principles
of natural philosophy.
Hawking: Newton's equations
for gravity explained the elliptical orbits
of the planets perfectly.
Kepler and Copernicus were vindicated.
According to Newton's theory
the universe ran like clockwork forever.
I think people were comforted by the thought
that even though they grew old and died,
the universe was eternal and unchanging.
Narrator: with new telescopes based on Newton's design
with a new vision of the sky based on his theories --
stargazing became popular.
It was the age of gentleman astronomers.
Man: I am William Brendan, The 7th Earl of Rosse,
Great-great-grandson
Of the 3rd Earl, who Was also another William
His great achievement was the building
of the great 6-foot telescope,
Or Leviathan of Parsons Town , as it was called,
That was the biggest and The most powerful telescope
in the world up till the present century.
Narrator: Brendan's Great-great-grandfather
In the Marshy countryside outside Dublin.
He made everything he needed himself, here.
He made it in a foundry that he set up
at the bottom of the moat,
that was fueled by the turf from the local bogs,
by making the most of all the resources he had.
I think he wanted to see farther
than anyone else had ever been able to see before.
He invited great scientists and astronomers
from all over the world
to show them what he saw here at Birr,
and that was amazing at the time,
because many other of the early astronomers
had guarded far more carefully,
and he didn't want to do that.
He wanted to share what he'd discovered with everyone.
Narrator: today, a kindred spirit
pays a call on the Earl of Rosse's telescope.
Man: my name is Francisco Diego.
I am involved in optical design In university college, London,
And we are planning to build a new mirror for this telescope.
Narrator: the antique Diego is restoring
worked the same way as Newton's telescope.
Images from space were concentrated
on a concave mirror.
In Newton's day, the mirror was 5 inches wide
200 years later, the earl's
was 6 feet in diameter.
Diego: with telescopes Like Galileo or Newton,
you could only see the solar system --
I mean the moon, the sun, the planets,
and almost nothing else.
Earl of Rosse: and you see here a plate
of the 6-foot telescope with an observer
here in position.
Remembering, of course, that this is a reflecting telescope
so the observers had to get into position at the top
to look right down the length of the tube
to see the image reflected
in the giant 6-foot mirror at the bottom.
I was browsing in your library,
and found this book --
This is "Transactions Of the royal society"
1850 or something like that.
And there is the 3rd earl's
Drawing of the whirlpool.
- The whirlpool galaxy
The first time the whirlpool galaxy was ever seen.
Narrator: telescopes Like the earl of Rosse's
gave new detail to distant wisps of light,
assumed to be strange gaseous clouds
on the fringes of our galaxy
The realization that these were indeed other galaxies
would only come after another conceptual breakthrough.
The universe was once again about to be redefined --
now by light,
born across time and the incomprehensible
distances of space.
Diego: spectroscopy is the analysis of light.
The information that we get from starlight or from sunlight
or from light in general is tremendous, is enormous.
Narrator: it was a german physicist
who discovered spectroscopy in the early 19th century --
Joseph von Frauenhofer.
Diego: he was an optical manufacturer.
He was working in a company which was building
lenses for astronomers.
He was very methodical.
He used to write everything he did.
And fortunately we have these texts
of his own very words
"In a shuttered room I allowed sunlight to pass
through a narrow opening in the shutters
onto a prism.
I found with the telescope almost countless
strong and weak vertical lines crossing the spectrum,
which however are darker than the remaining part
of the spectrum of the color image.
Some seem to be nearly completely black."
He couldn't explain the origin of these lines.
He just saw that part of the spectrum was missing.
Narrator: in the cryptic traces of its light,
the universe reveals its true colors.
We can see its chemical structure.
Light is originated in atoms
Light is originated
every time that electrons in these atoms
it's emitting or absorbing light at a particular frequency.
So each chemical element has a particular way of behavior
The electrons are jumping in particular places.
So depending on these places
is the position of the line in the spectrum.
"Ah, this is hydrogen."
But if the line appears here ?Ah this is not hydrogen, this is Sodium?
So in the solar spectrum we have the finger prints
of a lot of chemical elements
that we can identify in our labs,
because with the same equipment we take a spectrum off our lamp,
say, for example, an arc of iron --
and we can produce the same lines in our labs
And we match the lines from the sun
with the lines from the lamp in our laboratory,
and the match is perfect.
Hawking: using spectroscopy it was found
that the chemical content of our sun
was identical to that of any star in the universe.
Our sun, and our solar system itself,
was just one of an infinite number of others.
Perhaps we ourselves
have no special place in the universe.
Diego: the chemistry of stars is more or less the same
As the chemistry of the sun,
so the sun becomes a star or stars become suns.
This is a big revolution.
This is like a Copernican revolution,
when you abandon the idea
that the earth is the center of the universe,
and you say, well,
It's no longer the center of the universe
no center at least of the solar system
And that was a major revolution in science.
Now we have another revolution in which we say,
well, we are not so special about it,
because our own bodies, our own chemistry,
our blood, our bones, our skins --
they are made of hydrogen, nitrogen, oxygen, etcetera
sodium, etcetera.
And we find hydrogen and oxygen, etcetera,
in nebulae, in stars, in the universe.
So it is the same chemistry,
so there is nothing special about it.
Narrator: light, it turns out, is a messenger,
as swift as it is informative.
The news it bears is not just about chemistry.
It also signals the motion of the universe itself.
That discovery is owed in part to Christian Doppler.
Diego: the doppler shift has been, perhaps,
one of the tools in astrophysics,
I would say in cosmology now
because it is our speedometer, if you like.
It is the meter that we use to measure the speed
of almost everything in the universe.
Narrator: Doppler suggested that, as an object moves,
the light it emits will appear to be altered.
We can't observe this in everyday life,
because light moves too fast but we hear the same effect.
Sound is also carried in waves.
As it approaches, sound Is also carried in waves
Its waves are squashed together.
As it departs, the sound waves are stretched apart.
The change in pitch is audible and known as the doppler shift
[ Siren approaches ]
[ Pitch of siren decreases ]
By analyzing stars,
scientists found the doppler shift at work
in the light spectrum as well.
If a light source moves toward us,
The frauenhofer lines are shifted
towards the blue end of the spectrum.
If the light source is receding,
the lines shift towards the red.
Hawking: these extraordinary patterns in starlight
brought the dawn of a new age for cosmology.
It became possible to tell
not only what the universe was made of,
but also how it was moving.
The breakthrough came
by analyzing light from deep in the universe --
light seen through powerful new telescopes in America.
They could reveal
details of the universe never seen before.
Jastrow: everybody knew what The Milky Way galaxy was --
A collection of billions of stars
to which the sun belongs,
but nobody knew
What these little patches of nebulous material
that looked like spirals and pancakes and so on were.
And some people thought that the Milky Way galaxy
was the whole universe,
and these little spirals were wisps of gas in that universe.
The most famous person that worked at Mount Wilson
Was Edwin Hubble,
who came here when he was quite young, actually,
right after his service in world war I,
and Hubble had the golden touch.
He had a knack of picking the important problems.
Narrator: no problem seemed more puzzling
than the one posed by the Earl of Rosse
and his contemporaries.
What were those strange swirls they'd sighted?
Hubble wanted to know.
Jastrow: making use of the extraordinary clarity
of the atmosphere over Mount Wilson,
which is the best on the continent,
he was able to distinguish individual stars
in these little clouds of gas, these so-called nebulae,
and that told him in itself
that they were not wisps of gas in our galaxy,
but galaxies in their own right,
each one containing billions of stars,
and that the universe, the true universe,
was populated with countless numbers
of island universes,
each one like our Milky Way galaxy.
The distances that he measured
were absolutely stupefying to the astronomers of that time.
He found that the Andromeda nebula,
which is the closest galaxy to us like our own,
was at least a million light years away,
and a light year is 6 trillion miles --
a very, very great distance,
far outside the edge of our own milky way galaxy.
For the first time we knew how big the universe was
with that discovery.
Narrator: meanwhile, Doppler's theory came into play
under the studied gaze of a colleague of Hubble's
Vesto Slipher began to analyze light.
Jastrow: all of the galaxies that he could see around him
had red shifts,
towards longer wavelengths.
And that would mean, of course , that relative to us,
they were moving away.
When Slipher gave this report, everybody stood up and cheered
They didn't know what it meant but they had a gut feeling
that it was something cosmic in its significance.
Narrator: that galaxies were speeding away from us
was a discovery as striking as it was baffling.
But unknown to Slipher and Hubble,
an explanation was being formed an obscure german physicist.
His new model of the universe would be no less radical
than those of centuries past
and among its predictions would be the revelation
that the universe is rapidly expanding.
All the more remarkable was that this insight came
from a man now working as a patent clerk
because he had shown so little academic promise
His name -- Albert Einstein.
He was forced to learn
a lot of very complicated mathematics in order to do so.
But in 1915 finally the theory was born.
The theory was called General Relativity,
And it differed from the theory of gravity
that had held sway up until then for more than 200 years,
which was newtonian gravity.
In Newtonian gravity all objects in the universe attract each other directly.
Einstein's theory of gravity is radically different,
in fact, that the objects don't
attract each other directly at all.
One object makes dents or dimples or warps
in the fabric of space-time itself,
and the other object, as it moves by,
is actually bent by the curvature of space-time
by the fact that there's this dimple there.
And it looks like it's being attracted to the first object,
the object that's making the dimple,
but, in fact, it's not direct.
It's just reacting to The warpage of space-time
So one thing to understand about general relativity
is that you can't have a whole collection of matter
say, of galaxies or stars,
which are sitting in static configuration
with respect to each other , and expect them to stay there.
They won't.
They are going to collapse in towards each other.
So this means
that you can't have
A static model of the universe in general relativity.
The model -- the universe either has to be expanding
or it has to be contracting --
it has to be dynamical in some way.
It can't possibly be static.
Narrator: Einstein imagined that there must be
some unknown force keeping the cosmos
from collapsing in on itself.
In fact, he had predicted that the universe is expanding
Jastrow: the astronomers
looked at Slipher's discovery of the motion of the galaxies,
and the prediction that the universe expands,
and they said, aha! These are two sides of one coin.
They fit together.
And Hubble again with that golden touch
for working on the big problem
turned his attention to this question,
and he asked himself, how can I investigate it?
And the way he did so was to start to measure
the red shifts, as they are called --
the velocities with which
these galaxies are moving away from us.
Narrator: Hubble began the painstaking process
of comparing the distance and redshifts
of dozens of galaxies.
The results were staggering.
Jastrow: and he found something known today as Hubble's law,
quite extraordinary, that the red shift
or the velocity of recession from us
is proportional to distance.
If a galaxy at this distance
is moving away from you at a certain speed,
a galaxy twice as far away will be guaranteed
to be moving away from you at twice the speed.
Hubble actually changed
the picture of the universe
Because the ptolemaic picture was static,
And Newton's picture
of the universe was static
but Hubble showed that the universe is dynamic
Everything is moving away from everything else.
Greek astronomers thought -- most of them, not all of them --
that the earth was the center of the universe
Copernicus showed that that was not so,
and thought the sun was the center of the universe.
Other later astronomers showed
no, the sun was not the center of the universe
but many of them thought
that the center of our galaxy was the center of the universe
Hubble showed that there is no center.
That was a tremendous scientific, theological,
and philosophical accomplishment.
He showed that the universe as far as the telescope can see
is populated with countless numbers of island universes,
and there is no difference whatsoever.
There is no center.
The second implication in his finding was --
well, to explain it,
imagine that the picture of the expanding galaxies
moving away from us and one another
Is a movie strip.
Now run that in reverse.
And all the galaxies going backward in time
come closer and closer together.
And finally they all meet together at one point
Speaking loosely, because there is no one point,
there is no center in the universe.
They all come together in an infinitely dense
and yet infinitely extended moment
And beyond that, of infinite density,
one cannot go.
So that moment marks the beginning
or the birth of the universe
And all of the things that we see around us --
every star, every planet,
every living thing on the earth and in the cosmos
owes its genesis to that moment
You can call it the big bang
but you can also call it with accuracy
The moment of creation.
Narrator: today, our expanding vision
is keeping pace with an expanding universe
There are new revelations
of the big bang, of dark matter, of a strange breach of space
What are called black holes
A black hole is a gaping void in space
that sucks in and devours anything that gets too near.
It becomes compact, massive, and therefore able to --
if it encounters something else --
able to eat some more matter
It becomes the eater of all things.
Narrator: cosmologists are now
exploring a universe their predecessors
would hardly recognize.
Hawking: it seems that the kind of matter
of which we are made
constitutes only a small fraction
of the universe.
Over 90% is something we cannot even see --
dark matter.
It sort of puts one in --
as a human being --
into some perspective,
that the earth is not
the center of the solar system
we are not even made of particularly
cmmon matter that's around,
because most of it's dark matter.
Narrator: gradually, the heavens are yielding
their secrets to us.
These photographs are from the orbiting telescope
named after Hubble.
Hawking: from sitting at the center of the universe,
we now find ourselves orbiting an average-sized sun,
which is just one of millions of stars
in our own Milky Way galaxy.
And our galaxy itself
is just one of billions of galaxies
in a universe that is infinite and expanding.
But this is far from the end of a long history of inquiry
Huge questions remain to be answered
before we can hope to have
a complete picture of the universe we live in
To learn more about Stephen Hawking's Universe,
visit pbs online at the Internet address on your screen.
--Captions by vitac-- burbank, Pittsburgh, tampa, and washington, d.c.
?Stephen Hawking's Universe" was made possible
By Alfred P. Sloan foundation, To enhance public understanding
Of the role of science and technology,
The Arthur Vining Davis foundations,
The corporation for public broadcasting,
And viewers like you.
Corporate funding is provided by Amgen,
Unlocking the secrets of Life through biotechnology.
At Amgen, we produce medicines
That improve people's lives today
And bring hope for tomorrow.
"Stephen Hawking's Universe" is made possible
By Alfred P. Sloan foundation To enhance public understanding
Of the role of science and technology,
The Arthur Vining Davis foundations,
The corporation for public broadcasting,
And viewers like you.
Corporate funding is provided by Amgen,
Unlocking the secrets of Life through biotechnology.
At Amgen, we produce medicines
That improve people's lives today
And bring hope for tomorrow.