In 1988, I wrote a popular science book called A Brief History Of Time,
which sold over ten million copies.
I say that not to brag,
but to underline the deep fascination
we all have with our universe.
20 years ago, people rushed to buy Stephen Hawking's book.
It was an unlikely sensational best seller,
and he became an instant celebrity.
In the book,
he promised we would soon have the ultimate answer -
a theory of everything that explained how the universe began.
But 20 years on,
it remains tantalisingly elusive,
and Hawking's body is deteriorating.
Now his only way of communicating
is through one muscle in his cheek.
For Hawking, time is running out to unlock the mysteries
that could finally make him master of the universe.
These films are a journey into his extraordinary quest
for a theory of everything.
He does not see himself as a genius.
He sees himself as one of those lucky people
who get paid to do what they love.
It's just that his job is a little bit different from most people's.
20 years ago, Hawking said he wanted to know the mind of God.
He felt he was on the brink of delivering a simple, elegant set of laws
that would explain everything in our universe
and, more importantly, how it all began.
How can we understand the universe?
Is it arbitrary or is there a grand design?
Do we still need a God?
20 years on,
my need to find answers to the fundamental questions about our existence
is undiminished.
Hawking's need to find answers started early.
He was born in 1942, during the darkest days of World War II.
Hawking has always enjoyed the fact
that he was born 300 years to the day
after the death of that other revolutionary scientist, Galileo.
As a schoolboy, he was gifted and enquiring.
His father hoped he'd study medicine.
He chose physics.
But in 1963, while studying for his PhD,
he was told he had a life-threatening disease.
His response to the bad news was later made much of in the press.
How true is it that when you were first diagnosed,
that you listened to Wagner and drank heavily?
I took to listening to Wagner,
but reports in magazine articles that I drank heavily are an exaggeration.
The trouble is, once one article said it,
other articles copied it,
because it made a good story.
The outlook was bleak.
Motor neurone disease is progressive.
The nerves controlling the muscles degenerate to complete paralysis,
while the brain remains intact.
He was given two years to live.
Before then, as a student,
Hawking had, by his own admission, become somewhat directionless.
Now faced with an uncertain and nightmarish future,
he developed a fierce determination that would become his hallmark.
Often to the exclusion of all else,
he set his sights on the greatest questions in physics.
Professor Bernard Carr was a graduate student of Hawking's,
and became his close colleague.
And of course it's required a huge amount of effort for him...
..but in some sense
I think it's given Stephen the determination to overcome the problems
and it made him even more determined, I think,
to crack the ultimate problems of physics.
So young Hawking set off to crack the ultimate problem of physics.
He wanted to get an idea
of what the beginning of the universe looked like.
But to do that,
he'd have to attempt what everyone else thought was impossible.
Hawking was going to have to unify the two great,
but very different, theories of physics.
Einstein's theory of relativity is the theory of the very large.
Of planets, galaxies and space.
Quantum mechanics is the theory of the very small.
Of atoms, particles and forces.
But to understand how the universe came about,
Hawking would have to force the two together.
My life's work has been to unify the theories of the very large
and the very small.
Only then can we answer the more challenging questions.
Why are we here?
And where did we come from?
It's a quest that, despite near total paralysis,
he's not about to give up on.
He's a very tenacious, courageous individual,
but he never thinks of it like that, he just gets on with it.
That's really how he gets on with everything.
He can be quite exhausting as well, you know, very demanding.
He doesn't get tired like the rest of us.
We all get very tired, but he can keep going.
Physicists love to explain how our universe arose and how it works.
We understand enormous amounts,
but when asked, "How did it all come to be?,
we don't have one single answer yet"
Can I have a minute, please?
Stephen Hawking is the Lucasian Professor of Mathematics
at Cambridge University,
a post once held by Sir Isaac Newton.
Age 66, Hawking still tirelessly
puts in a full week of teaching and research.
Hawking's schedule is frantic.
As well as trying to find out how our universe came about,
he tries to satisfy an incessant demand for his illustrated lectures.
Can you hear me?
(ALL) Yes.
According to the Boshongo people of Central Africa,
in the beginning there was only darkness,
water and the great god Bumba.
One day Bumba, in pain from a stomach ache, vomited up the sun.
The sun dried up some of the water, leaving land.
Still in pain, Bumba vomited up the moon,
the stars and then some animals -
the leopard, the crocodile, the turtle and finally, man.
This creation myth, like many others,
tries to answer the questions we all ask.
Why are we here?
Where did we come from?
"Why are we here?"
was a question Hawking asked himself a lot back in 1965,
while contemplating what the doctors had told him
might well be a very short life ahead.
Then he heard reports of a lecture given in London
by a brilliant young mathematician, Roger Penrose.
Sorry to interrupt but Roger Penrose is here.
I was wondering, shall I bring him up?
Yes.
Thank you, Stephen.
Penrose's ground-breaking work catapulted Hawking out of his depression.
I certainly remember Stephen in lectures
asking extremely awkward questions at the ends of seminars,
or in the course of seminars -
that was the thing that struck me particularly about him.
They were penetrating questions I should say, not just awkward.
Penrose had given Hawking a glimpse
of how physics could be used to answer the question,
"Why are we here?"
For both Penrose and Hawking,
the starting point was Einstein's Theory of Relativity.
The theory of the very large.
It explains how the universe works,
and how insignificant our place in it is.
One small planet in a tiny galaxy, lost in the vast realms of space,
as cosmologist Pedro Ferreira explains...
Now, let's imagine that this enormous library is our visible universe,
and we know that the universe is sprinkled with galaxies -
and I really mean sprinkled -
there's a lot of empty space around each galaxy.
Let's take our galaxy, the Milky Way.
It would comfortably fit in a full stop in Stephen's book.
Our galaxy is microscopic
compared to the gigantic tracks of empty space that dominate the universe.
But Einstein showed that all that empty space
turns out to have some remarkable properties.
Let's imagine that this basketball is a celestial object like a star,
OK, and let's imagine that this book shelf with these books is space.
In our classical view of space, it would be rigid like this,
it would just be this static thing, this thing that is unresponsive,
but in our modern view, this star as it moves through space,
it warps it, it dents it, it bends it,
and other objects that then move through this space
will feel this warp, will feel these bends, these warps and
will move according to that.
They won't move in straight lines,
they'll feel these bends and they'll curve.
The fact that big objects like stars can actually bend and curve space,
is now an everyday notion to astrophysicists like Kim Weaver.
What we're talking about in terms of astronomy
and cosmology are objects that have a huge amount of mass -
a planet, a planet-sized object
or a moon-sized object or a star-sized object.
The mass of this object bends space around it.
If the ball here that is at the centre of this sheet
is representing the sun,
and this penny is representing a planet like the earth,
then you can use the penny to demonstrate
how the earth orbits the sun.
Most of us think of gravity as an invisible force,
which holds us on the earth
and keeps the earth in orbit round the sun.
So far, so good.
But what physics says is really happening
is that planets are trapped in areas of curved space.
The earth is actually rolling round and down into an area of space
warped by the sun.
The penny rolls in quickly,
but of course it'll take the earth billions of years to hit the sun.
And it's the curvature of space caused by the earth itself
which holds us in place on our planet.
Hawking knew Einstein's work like the back of his hand,
but what excited him was that Penrose had used the theory
to discover something altogether bizarre.
It was possible not just to bend space,
but to twist it right back in on itself,
to create a black hole.
Penrose showed that when a massive star burns out,
it collapses in on itself in a spectacular way.
Something that was many times bigger than our sun
is compressed to a size smaller than an atom.
It becomes so incredibly dense that it pulls space back towards it.
Everything in that warped space is eaten up.
Even light cannot escape its clutches.
Around the ultra-dense centre, there forms a sphere of darkness,
that we now call a black hole.
But Penrose hadn't just shown that a massive star
could collapse into a black hole.
What gripped Hawking was that Penrose had proved,
using Einstein¡¯s equations,
that at the very centre of a black hole,
there had to be a plughole,
down which matter, space and time disappeared.
The plughole had a fancy mathematical name -
a singularity.
Hawking was excited and mystified.
In 1965,
Roger Penrose showed that if a star collapsed below a certain critical radius,
it would inevitably develop a singularity,
at which time would come to an end.
At first I didn't understand either the significance
or the proof of this result.
Hawking became obsessed with understanding the singularity.
It was a poignant choice of specialist subject.
A young man who'd been told he had two years to live
was wrestling with a point in space
where the universe disappeared out of existence.
This was typical of Hawking's stubbornness,
refusing to accept the limitations of his body, or his brilliant mind.
And even in his private life, he exhibited the same bravado.
Despite his family's concerns over his health,
he met, fell in love with, and married Jane Wilde, a languages student.
As Jane later remembered in an interview,
death seemed to be all around.
It was the time of the Cold War with Russia,
an age of defiance.
It wasn't a terribly difficult decision to take, to marry Stephen,
because I think a lot of people had forgotten that, at that time,
every day, one read reports in the newspapers
that a nuclear war was likely to break out in the next year or two.
People said they weren't going to have children
because there was going to be a nuclear war,
and the fact that Stephen had been diagnosed as only having a couple of years to live
didn't really seem to be very much different to the situation
that was facing the rest of us, anyhow.
But out of this gloom, Hawking managed to conjure up...
light.
Out of what seemed to be the end of everything,
he found a beginning.
Penrose had shown that bits of the universe
could be sucked into a singularity,
a tiny plughole at the centre of a black hole.
Hawking took Penrose's equations and reversed them.
Like running a film backwards.
Where Penrose showed the universe disappearing into a black hole,
Hawking showed it came from one.
For thousands of years, man had wondered how the universe began.
Now, a young PhD student from Cambridge
had come up with an answer.
It was an incredible turning point in our understanding of the world.
But Hawking's results raised as many questions as they solved.
He could prove the universe started from a tiny, single point,
but frustratingly, not how or why.
It seemed to many that this inexplicable, sudden appearance of the universe,
expanding out from a microscopically tiny point,
had to be a miracle.
There are two attitudes one can take
from the results of Penrose and myself.
One is that God chose how the universe began
for reasons we could not understand.
At a conference on cosmology in the Vatican,
the Pope told the delegates that it was OK
to study the universe after it began.
But they should not enquire into the beginning itself,
because that was the moment of Creation and the work of God.
I was glad he didn't realise I had presented a paper at the conference
suggesting how the universe began.
I didn't fancy the thought of being handed over to the Inquisition
like Galileo.
LAUGHTER
APPLAUSE
Hawking's response to his results
was to decide that the equations he'd used,
Einstein's Theory of Relativity, were not the whole story.
General relativity makes a prediction
that the universe was once infinitely small,
but it loses the ability to describe the universe when it was tiny.
Hawking now knew that our entire universe
did start out as a tiny dot,
but he wasn't going to be happy
until he could describe how that dot came about.
Hawking had lain down a huge challenge for himself
and the rest of physics.
As physicist Michio Kaku explains.
"The bottom line is,
Einstein's equations are useless at the instant of the Big Bang.
We physicists say that a long time ago,
the universe was so small it was smaller than a basketball,
you could put the universe in your pocket,
it was smaller than an electron.
Some people call it a "singularity of infinite gravity".
Now, that's silly.
There's no such thing as infinite gravity,
it just means that we use the word "singularity" to hide our ignorance.
We don't know what this singularity is.
Unraveling this singularity, this tiny point of creation,
became Hawking's life's work.
(MOUTHS)
But it was a race against time, against encroaching disability.
Hawking has defied all the predictions of his doctors,
his disease has progressed much more slowly than they thought it would.
But today, he has only the use of his facial muscles.
"He communicates, actually using just one muscle on his cheek.
There's a little censor, and whenever he moves his cheek,
that sends a pulse through to his computer.
By tensing that one muscle,
he can do everything from checking his e-mail,
to speaking, to browsing the internet.
I was there with him when he changed from using the finger switch
on to the blink switch, and it was quite a...
Well, the blinks which sat in a cupboard for 13 years
before he would even think of trying it,
so he tends to go with what he knows.
Every time he changes to another type of technology,
he seems to see that as admitting defeat.
So, he's very resistant to changing to other technologies.
Can you finish in 10 minutes?
10 minutes? 15. Maybe!
It becomes very apparent that his struggle is daily,
it's not just something that he gets used to,
then it's not a problem any more.
At the same time, you realise how much help he's got.
You know... That doesn't mean it's easy for him.
But Hawking is nothing if not determined,
and back in the 1970s, he set his sights on solving the big problem -
what happened at the moment of Creation?
In the early 1970s, black holes were the agents of death,
the place where everything we know about the cosmos
came to a chilling end.
But to a young physics researcher like Stephen Hawking,
they were an exciting challenge.
He'd already shown that the universe arose from a single, tiny point
now he wanted a complete theory of everything.
A theory that would describe the moment of universe's creation
in precise detail, and again, black holes would point the way.
My own work on black holes
began with a Eureka! moment while getting into bed in 1970.
In 1970, getting into bed was a protracted business for Hawking.
His paralysis was increasing
and he needed constant care and attention from his wife, Jane.
And they'd started a family.
But despite his disability, the couple were managing.
He'd taken a research post at Cambridge University
and was eagerly pursuing his quest to understand the universe.
What Hawking had glimpsed that night getting into bed
was something very peculiar about black holes.
Hawking knew that every object in the universe
could be heated up or cooled down,
but black holes were different.
Heat, would never get out of a black hole, it seemed.
This started to niggle Hawking,
but it would turn out to be the key to the mystery of creation.
Hawking was about to attempt something
no other physicist had ever achieved.
For 50 years physicists had failed to unite the theories
of the very big and the very small.
Einstein's theory of gravity
would not fuse with the very different theory of how atoms work -
quantum mechanics.
But what Hawking had glimpsed
was a point where the two must clash -
at the very edge of a black hole.
What happens if you have a black hole
which is sitting there, it's black,
that's why it's called a black hole,
no light comes out of it.
What happens if you include the effects of quantum mechanics?
Einstein's theory said the black hole was a smooth, perfect sphere.
Hawking plunged it into a sea of particles and atoms.
The two theories sputtered and fought each other.
Somehow, Hawking must bring them together.
The problem of reconciling Einstein's theory with quantum mechanics
is one of the holy grails of modern physics.
What Hawking did in the early '70s was,
he didn't try to solve this problem completely,
but he tried to put quantum mechanics and general relativity together
in a very limited fashion.
What was all the more remarkable
was that now unable to write down long equations and calculations,
Hawking had to imagine the whole process in his head.
As well as space and black holes,
Hawking had to visualise a world we are all unfamiliar with,
the bizarre realm of the very small, of the atom.
A good way to think of an atom is a bit like our solar system.
You've got a nucleus at the centre and electrons whizzing around.
Now, let's imagine that this marble is the nucleus of an atom.
An electron will be the width of this hair.
Now again, we're used to seeing in textbooks
that an electron is more or less this distance from a marble,
but it's not, it's not this far,
it's not this far.
It's not this far...
It's not even this far...
Not even here.
On this scale, where the nucleus is the size of a marble
and an electron is the width of a hair,
the electron would actually be two miles away from the nucleus.
At the atomic level, particles are almost not there.
They're less like solid lumps of matter
and more like tiny empty force fields,
and as force fields, they shimmer.
Physicists often describe them as waves.
Water, sound and light can behave like waves,
but so too can the parts of the atom
and that means they can spread out
to be in more than just one place at a time.
Common sense says that when I fire this gun,
one ball hits one target, that's it.
If this is an electron gun hitting many targets,
I find out that one electron has a probability
of hitting many targets at the same time.
Now, that violates common sense.
I thought it was one ball, one target.
In the quantum world, common sense is violated.
Common sense has no place in the quantum world.
Hawking knew that atoms were not like little billiard balls.
They turn out to be much more fuzzy and erratic.
How could he join Einstein's stars and planets
that float sedately along nice curved lines,
with atoms that buzz around in a frenzy?
At a very tiny level,
our universe is like a crazy dance of waves
jangling to a myriad of beats.
Particles appear and disappear at random,
and at this level nothing is certain, not even existence.
Atoms are a bit like people.
They're very hard to predict with absolute certainty.
They do roughly what you'd expect of them,
but never exactly.
With atoms, it's even hard to be totally certain
whether they exist or not.
Sometimes, Hawking knew, atoms pop up
where there should be absolutely nothing around.
In fact, out in space, it happens all the time.
The theory of the very tiny says space is never empty.
At an atomic level,
there is always a tiny, tiny amount of activity.
But the theory of the very big
says nothing exists at the edge of a black hole.
Hawking realised this was where the two theories clashed.
He had to find out what was really going on.
According to the theory of the very tiny, in empty space,
there are pairs of subatomic particles that emerge out of the void,
exist for a tiny moment and then destroy each other.
And so the idea is that out of nothing if you like,
a pair of particles is created and then exists for a short time
and then annihilates,
and that's happening throughout space,
so it's happening there and it's happening there
and it's happening there.
This pair of particles is like yin and yang,
night and day,
opposites that would not exist without each other.
One has positive mass and the other has negative mass.
But Hawking asked, what would happen
if this pair of particles bumped up against a black hole?
Hawking realised that the positive particle
would have just enough energy to escape the black hole,
but the particle with negative mass would fall in
and it would do something extraordinary to the black hole.
The particle that goes inside the black hole
eventually decreases the mass of the black hole.
It effectively has negative mass.
But the particle that goes off to the distant observer,
is there observed as part of radiation.
Although we now understand why black holes
have to give off thermal radiation,
it came as a complete surprise at the time.
At first I thought I must have made a mistake.
But Hawking had not made a mistake.
Around a black hole is an almost imperceptible microscopic glow.
Positive mass particles fly off from it,
behaving just like heat.
Negative mass particles fall in.
Slowly, almost imperceptibly,
they decrease the mass of the black hole
and this eventually has catastrophic consequences.
So what the Hawking result implies,
it means that the black hole, instead of being black,
is actually always emitting radiation.
What is happening is that for most of its life,
the black hole is gently sizzling away,
but eventually it gets smaller and smaller,
the temperature gets hotter and hotter
and eventually it gets to a point where it's so hot
that it essentially explodes,
it loses all the rest of its mass in a very, very short time.
Hawking had transformed the black hole from a ball of nothing
into a galactic monster, that chews up the universe
and spits out fire and brimstone.
When black holes were first thought of
and when I first started studying black holes,
I remember thinking, "Oh, a black hole, it's the end of everything,
a star collapses down and everything disappears into it
and nothing ever comes out,
so maybe it's really boring?"
But really, black holes represent our best way
to have an ultimate test of the physics of understanding the universe.
And astronomy has borne out Hawking's discovery.
Black holes now seem to be where it all happens.
They're the engines that rip up the cosmos and create new stars
and jets of energy and matter.
"Black holes are not ultimate end points,
they really are beginnings of something -
around a black hole you have enormous amounts of activity going on.
You have stars being ripped apart
and you have discs of accreting matter swirling around,
you have cauldrons of heat and light around a black hole,
you have jets being produced by a black hole.
You have particles coming out at half the speed of light,
being shot away from a black hole,
you have stars being born around a black hole.
There's an enormous amount of stuff going on
caused by the fact that that black hole's really there,
and that's exciting.
Hawking had taken a great leap forward in his quest.
He'd linked the theories of the big and the small
for the first time ever in physics.
What was really amazing about this paper,
really one of the most beautiful papers in the 20th century,
is that his argument that this could happen
relies on almost no assumptions.
The assumptions about the nature of quantum mechanics
and the nature of general relativity,
that basically every living physicist will agree with.
But Hawking had done more than just show that black holes were complex.
The theory of the very tiny
was starting to unlock the secrets of the very large.
Could he now apply it to the entire universe?
Could he now explain the big bang?
By applying quantum mechanics to the edge of the black holes in the 1970s,
I was able to revolutionise our understanding of them.
To expand our understanding further,
we need to bring quantum mechanics into the heart of the black hole.
In the 1970s,
it seemed Hawking had only to wrest the key to the universe
from the inner reaches of his brilliant mind.
But more humble problems of health, love and fame
would try to tempt him away from his devotion to physics.
This world that is so familiar,
how did it come about?
Can we ever discover how all this came to be?
Stephen Hawking runs a department
that is still trying to find the answer.
He has his PhD students and they have supervision,
and they come in every week and have lunch, and they talk about ideas,
and if they get stuck, they can come to him.
You have to have exceptionally good students to be able to
cope with the heavy work that they have to have, and also with
the communication, they really have to know their subject.
You have all survived the summer.
LAUGHTER
Very well.
Start
Aged 66, when many are retiring,
Hawking shows no sign of giving up his quest.
The food's improved!
Has it improved the work-rate of the students?
No!
I think he caught you there!
Hawking's life's work has been to come up with a theory of everything,
a theory that explains how our universe works and how it arose.
In the 1970s, he had huge success
using the theory of the tiny, quantum mechanics,
to better explain black holes.
But in the 30 years since,
using it to explain the entire universe
has turned out to be just a bit harder.
Hawking has admitted that he was over-confident.
The early 1960s idealism of his work and his personal life
have waned somewhat.
His relationship with his family
was often strained by his drive to succeed.
His wife Jane, interviewed in 1989,
said despite her dedication,
she struggled to cope with someone whose whole focus was physics.
His determination has now rather outstripped mine.
I cannot keep up with him.
I do think he tends to overcompensate for his
condition by doing absolutely everything that comes to his notice.
I'm not a scientist.
I'm not an appendage of Stephen, as I very much feel I am.
When we go to some of these official gatherings, I mean,
sometimes I'm not even introduced to people.
Hawking's dedication to his science came with a personal cost.
By 1985, just before his meteoric rise to fame,
the Hawkings' marriage was under considerable strain,
and the couple were drifting apart.
Jane took her family on holiday,
while Hawking went on a working trip to Switzerland alone.
But as he was visiting the huge particle accelerator at CERN, near Geneva,
Hawking suddenly contracted severe pneumonia.
It seemed he might not make it.
Jane rushed to his side.
For days, he struggled on life support.
But with characteristic stubbornness, Hawking pulled through.
He'd needed a tracheostomy,
which meant he completely lost his ability to speak unaided.
The famous voice box followed soon after.
Then came the book.
Through it all,
Hawking's eye was, and still is, on the prize.
The theory of everything.
Nevertheless,
even though the job has been more difficult than one might have hoped,
I think there is still every indication
that there is a final theory and that we may get there,
but it just proves much more complicated than we originally hoped.
It is, after all, the toughest job in science.
Hawking's trying to peer back to 13.7 billion years ago,
to the start of everything.
His main stumbling block has been getting the theory to explain
what the entire universe was like back then,
when it was all compressed to a size smaller than an atom.
Although the universe is very big now,
the observable universe is something like 13,000 million light years,
the distance light has travelled since the Big Bang,
we know that that entire region
must once have been compressed into a very, very small scale.
But, of course, once the universe is compressed into a very small scale
or a very high density,
we know we are in the domain of quantum theory.
Using the theory of the tiny,
Hawking has made huge progress
in describing the birth of the universe.
But there is one part that eludes him.
He's found it impossible so far
to describe how gravity must have worked
at the moment of the Big Bang.
If we want to know what happened when the universe began,
we have to have a theory that can describe gravity on a very small scale.
For the last 30 years,
Hawking has struggled to find a way
to describe gravity with quantum theory,
but he has unshakeable faith
that the theory of the tiny will eventually win through.
And he's not alone.
Today all of physics is racing along beside him.
Incredible experiments are now being built
in outer space and deep underground,
which will try to probe deeper into the very moment of creation.
There is excitement in the air,
a sense that the problem of gravity in the early universe will be solved,
and that a theory of everything is just waiting to be found.
Whether he finds it first or not,
Hawking is philosophical about his part in this great journey.
I was unlucky to get motor neurone disease,
but lucky in almost everything else.
I have three very attractive children,
success in my scientific work
and a real sense of satisfaction at having achieved all of this,
despite the difficulties.
Not many people can say this.
Is there anything you wish you'd achieved professionally
that you haven't already?
I feel I have achieved quite a lot,
but one would always like to have done more.
In particular, I would like to have found a complete theory
of quantum gravity in the early universe.
Still, that wouldn't have left much for anyone else to do.
Subtitles by Red Bee Media Ltd