Original subtitles

Hello.

My name is Stephen Hawking -

physicist, cosmologist,

and something of a dreamer.

Although I cannot move

and I have to speak through a computer,

Narrator: in my mind, I am free...

Free to explore

the deepest questions of the Universe.

Among them, the deepest of all...

ls there a God who created and controls the Universe -

from the stars and the planets

to you and me?

Finding out takes us on a journey

through the laws of nature,

for there, I think, lies the answer

to the age-old mystery

of how the Universe was made and how it really works.

Check it out.

Hawking: I recently published a book

that asked if God created the Universe.

It caused something of a stir.

People got upset that a scientist

should have anything to say on matters of religion.

I have no desire to tell anyone what to believe,

but for me, asking if God exists

is a valid question for science.

After all, it is hard to think

of a more important or fundamental mystery

than what or who created and controls the Universe.

[ Thunder crashes ]

Narrator: Long ago, the answer was almost always the same.

Gods made everything.

[ Thunder crashes ]

The world was a scary place.

So even people as tough as the Vikings

believed in supernatural beings

to make sense of natural phenomena,

like lightning

or storms.

[ Thunder crashes ]

[ Thunder crashes ]

Another god, Aegir, caused stormy seas.

But the god they feared the most was named Skoll.

He was responsible for the terrifying natural event

that we now call a solar eclipse.

Skoll was a wolf god who lived in the sky.

Sometimes, he would eat the Sun,

causing the dreadful moment when day turned to night.

Without a scientific explanation,

imagine how disturbing it would have been

to see the Sun vanish.

The Vikings responded

in the only way that made sense to them.

[ All shouting ]

They tried to scare away the wolf.

[ Shouting stops ]

[ All cheering ]

The Vikings believed that their actions

caused the Sun to return.

Of course, we now know they had nothing to do with it.

The Sun would have reappeared anyway.

It turns out that the Universe

is not as supernatural or mysterious as it seems.

But it takes more courage than even the Vikings had

to discover the truth.

Mere mortals like you and I

can understand how the Universe works.

This was realized long before the Vikings

in ancient Greece.

In about 300 B.C.,

a philosopher called Aristarchus was fascinated by eclipses, too,

especially eclipses of the Moon.

He was brave enough to question

whether they really were caused by gods.

Aristarchus was a true scientific pioneer.

He studied the heavens carefully

and reached a bold conclusion.

He realized the eclipse was actually the shadow of the Earth

passing over the Moon

and not a divine event.

Liberated by this discovery,

he was able to work out

what was really going on above his head

and draw diagrams that showed the true relationship

of the Sun...

The Earth...

And the Moon.

From there, he reached even more remarkable conclusions.

He deduced that the Earth was not the center of the Universe,

as everyone had thought,

but instead orbits the Sun.

In fact, understanding this arrangement

explains all eclipses.

When the Moon casts its shadow on the Earth,

that's a solar eclipse.

And when the Earth shades the Moon,

that's a lunar eclipse.

But Aristarchus took it even further.

He suggested the stars were not chinks in the floor of heaven,

as his contemporaries believed,

but that stars were other suns like ours,

only a very long way away.

What a stunning realization it must have been.

The Universe is a machine

governed by principles, or laws,

laws that can be understood by the human mind.

Hawking: I believe the discovery of these laws

has been humankind's greatest achievement,

for it's these laws of nature, as we now call them,

that will tell us whether we need a God

to explain the Universe at all.

For centuries, it was believed that disabled people like me

were living under a curse inflicted by God.

While I suppose it's possible

that I've upset someone up there,

I prefer to think

that everything can be explained another way -

by the laws of nature.

So, what exactly is a law of nature,

and why is it so powerful?

I'll show you with a game of tennis.

Narrator: Tennis is governed by two sets of laws.

One set is man-made -

the rules of the game.

They govern things such as the size of the court,

the height of the net,

and what determines if a shot is in...

or if a shot is out.

These rules could conceivably be changed

if the governing body of tennis so desired.

But the other set of laws that apply to the game

are fixed, immutable.

They govern what happens to the ball...

When it is hit.

The force and angle of the racket strike

determines exactly what happens next.

The laws of nature

are a description of how things actually work

in the past, present, and future.

In tennis,

the ball always goes exactly where they say it will.

And there are many other laws at work here, too.

They govern everything that is going on -

from how the energy of the shot

is produced in the players' muscles...

to the speed at which the grass grows

beneath their feet.

But what's really important is that these physical laws,

as well as being unchangeable, are universal.

They apply not just to the flight of a ball

but to the motion of a planet

and everything else in the Universe.

Unlike laws made by humans,

the laws of nature cannot ever be broken.

That's why they are so powerful

and, when seen from a religious standpoint,

controversial, too.

Hawking: if you accept, as I do,

that the laws of nature are fixed,

then it doesn't take long to ask,

what role is there for God?

This is a big part of the contradiction

between science and religion.

And although my views have recently made headlines,

it is actually an ancient conflict.

[ Bell tolls ]

Narrator: Back in 1.277,

Pope John XXl felt so threatened by the idea of laws of nature

that he decreed them a heresy.

Unfortunately, that did nothing to change the law governing gravity.

A few months later,

the palace roof collapsed and fell on the Pope's head.

[ Wood cracking ]

[ Bell tolling ]

But organized religion soon found a solution.

For the next few hundred years,

it was simply stated

that the laws of nature were the work of God,

and God could break them if he wished to.

This view was reinforced

by the idea that our perfect blue planet

was quite still at the center of it all,

that all the stars and planets rotated around the Earth

like some carefully designed clockwork.

Aristarchus' idea to the contrary

had been long forgotten.

But humans are naturally inquisitive,

and some, such as Galileo Galilei,

couldn't help but look at God's clockwork once more.

It was 1609, and this time,

the results would change everything.

Galileo is the founder of modern-day science

and one of my heroes.

He thought, as I do,

that if you looked at the Universe closely enough,

you could discern what was really going on.

He was so determined

that he perfected lenses that, for the first time,

could magnify the night sky by 20 times.

Carefully, he assembled them

into a telescope.

From his house in Padua,

he used this telescope

to study Jupiter

night after night

and made a wonderful discovery -

three tiny dots very close to the giant planet.

To begin with, he thought the dots must be very faint stars,

but then as he watched for a few nights,

he saw that they moved.

And then a fourth dot appeared.

Sometimes, one of them would vanish behind Jupiter

and then reappear.

He realized they had to be moons circling the vast planet.

Here was proof positive

that at least some objects do not orbit the Earth.

Inspired by this discovery, Galileo went on to prove

that the Earth must, in fact, orbit the Sun.

Aristarchus had been right all along.

Galileo's discoveries triggered a revolution in thought

that would ultimately loosen the grip of religion over science.

But back in the 17th century,

they got him in a lot of trouble with the church.

He narrowly avoided execution

by recanting his so-called heresy

and was confined to house arrest

for the last nine years of his life.

Legend has it

that even as he confessed his sin, he muttered,

"but it does move."

Over the next 300 years,

as more and more of the laws of nature were discovered,

science began to explain all kinds of things -

from lightning, earthquakes, and storms

to what makes the stars shine.

[ Thunder rumbling ]

Each new discovery

further removed the need for a God.

After all, if you know the science behind an eclipse,

you're much less likely to believe

in wolf gods that live in the sky.

Hawking: Science does not deny religion,

just offers a simpler alternative.

But several mysteries remain.

After all, if the Earth moves,

could it be God that moves it?

Ultimately, did God create the Universe

in the first place?

Narrator: In 1985, I attended a conference on cosmology

at the Vatican in Rome.

The gathering of scientists

had an audience with Pope John Paul ll.

He told us that it was okay

to study the workings of the Universe.

But we should not ask questions about its origin,

for that was the work of God.

Hawking: I am glad to say I, for one,

haven't followed his advice.

I can't simply switch off my curiosity.

I believe it's a cosmologist's duty

to try and work out where the Universe came from.

Luckily, it's not quite as difficult as it seems.

Narrator: Despite the complexity and variety of the Universe,

it turns out that to make one,

you need just three ingredients.

Let's imagine we could list them in some kind of cosmic cookbook.

So, what are the three ingredients we need

to cook up a Universe?

The first is matter -

stuff that has mass.

Matter is all around us,

in the ground beneath our feet...

and out in space...

dust, rock, ice,

liquids, vast clouds of gas,

massive spirals of stars

each containing billions of suns,

stretching away for incredible distances.

The second thing you need is energy.

Even if we've never thought about it,

we all know what energy is.

Something we encounter every day.

Look up at the Sun,

and you can feel it on your face...

energy produced by a star 93 million miles away.

Energy permeates the Universe...

driving the processes that keep it a dynamic,

endlessly changing place.

So, we have matter, and we have energy.

The third thing we need to build a Universe

is space...

Lots of space.

You can call the Universe many things -

Awesome...

Beautiful...

Violent.

But one thing you can't call it is cramped.

Wherever we look, we see space...

And more space and even more space,

stretching in all directions.

It's enough to make your head spin.

So, where could all this matter, energy, and space come from?

We had no idea until well into the 20th century.

[ Bell tolling ]

The answer came from the insights of one man...

Probably the most remarkable scientist

who has ever lived.

His name was Albert Einstein.

Sadly, I never got to meet him,

since I was only 13 when he died.

Einstein realized something quite remarkable -

that two of the main ingredients needed to make a universe,

mass and energy,

are basically the same thing,

two sides of the same coin, if you like.

His famous equation, e=mc�,

simply means that mass

can be thought of as a kind of energy

and vice versa.

So, instead of three ingredients,

we can now say the Universe has just two -

energy and space.

So, where did all this energy and space come from?

The answer was found

after decades of work by scientists.

Space and energy were spontaneously created

in an event we now call

the Big Bang.

At the moment of the Big Bang,

an entire universe full of energy came into existence,

and with it, space.

It all inflated,

just like a balloon being blown up.

So, where did all this energy and space come from?

How does an entire universe full of energy,

the awesome vastness of space and everything in it,

simply appear out of nothing?

For some, this is where God comes back into the picture.

It was God that created the energy and the space.

The Big Bang was the moment of creation.

But science tells a different story.

At the risk of getting myself into trouble...

Hawking: I think we can understand

far more the natural phenomena that terrified the Vikings.

We can even go beyond the beautiful symmetry

of matter and energy discovered by Einstein.

We can use the laws of nature

to grasp the very origins of the Universe

and discover the existence of a God

as the only way to explain it.

As I was growing up in England after the Second World War,

it was a time of austerity.

We were taught that you never get something for nothing.

But now, after a lifetime of work,

I think that, in fact, you can get a whole universe for free.

Narrator: The great mystery at the heart of the Big Bang

is to explain how an entire fantastically enormous Universe

of space and energy can materialize out of nothing.

The secret lies

in one of the strangest facts about our cosmos.

The laws of physics demand the existence

of something called negative energy.

To get your head around this weird but crucial concept,

let me draw a simple analogy.

Imagine a man wants to build a hill

on a flat piece of land.

The hill will represent the Universe.

To make this hill, he digs a hole in the ground

and uses that soil to build his hill.

But, of course, he's not just making a hill.

He's also making a hole -

in effect, a negative version of the hill.

The stuff that was in the hole has now become the hill.

So it all perfectly balances out.

This is the principle behind what happened

right at the beginning of the Universe.

When the Big Bang produced a vast amount of positive energy,

it simultaneously produced

the same amount of negative energy.

In this way, the positive and the negative

add up to zero -

always.

It's another law of nature.

So, where is all this negative energy today?

It's in the third ingredient in our cosmic cookbook.

It's in space.

This may sound odd,

but according to the laws of nature

concerning gravity and motion,

laws that are among the oldest in science,

space itself is a vast store of negative energy -

enough to ensure that everything adds up to zero.

I'll admit that unless mathematics is your thing,

this is hard to grasp,

but it's true.

The endless web of billions upon billions of galaxies,

each pulling on one another by the force of gravity,

acts like a giant storage device.

The Universe is like an enormous battery

storing negative energy.

The positive side of things -

the mass and the energy we see today -

is like the hill.

The corresponding hole, or negative side of things,

is spread throughout space.

Hawking: So, what does that mean

on our quest to find out if there is a God?

It means that if the Universe adds up to nothing,

then you don't need a God to create it.

The Universe is the ultimate free lunch.

Narrator: Since we know

that the positive and negative in the Universe adds up to zero,

all we have to do now is work out what -

or, dare I say, who -

triggered the whole process in the first place.

What could cause the spontaneous appearance of a universe?

At first, it seems a baffling problem.

After all, in our daily lives,

things don't simply materialize out of the blue.

You can't just click your fingers

and summon up a cup of coffee when you feel like one, can you?

You have to make it out of other stuff,

like coffee beans,

water,

perhaps some milk and sugar.

But travel down into this coffee cup...

Through the milk particles...

Down to the atomic level...

And right down to the subatomic level...

And you enter a world

where conjuring something out of nothing

is possible...

At least for a short while.

That's because at this scale,

particles such as protons

behave according to the laws of nature

we call quantum mechanics.

And they really can appear at random,

stick around for a while,

and then vanish again...

To reappear somewhere else.

Since we know the Universe itself was once very small -

smaller than a proton, in fact -

this means something quite remarkable.

It means the Universe itself,

in all of its mind-boggling vastness and complexity,

can simply have popped into existence

without violating the known laws of nature.

From that moment on,

vast amounts of energy were released

as space itself expanded.

A place to store all the negative energy

needed to balance the books.

But, of course, the critical question

is raised again.

Did God create the quantum laws

that allowed the Big Bang to occur?

In a nutshell...

Hawking: Do we need a God to set it all up

so that a Big Bang could...

Bang?

I have no desire to offend anyone of faith,

but I think science

has a more compelling explanation

than a divine creator.

Our everyday experience makes us convinced

that everything that happens must be caused

by something that occurred earlier in time.

So it's natural for us to assume that something -

perhaps God -

must have caused the Universe to come into existence.

But when we're talking about the Universe as a whole,

that isn't necessarily so.

Let me explain.

Imagine a river

flowing down a mountainside.

What caused the river?

Well, perhaps the rain -

rain that fell earlier in the mountains.

But, then, what caused the rain?

A good answer would be the Sun -

the Sun that shone on the ocean

and lifted water vapor up into the sky

and made clouds.

Okay.

So, what caused the Sun to shine?

Well, if we look inside,

we see the process known as fusion,

in which hydrogen atoms join to form helium,

releasing vast quantities of energy in the process.

So far, so good.

Where does the hydrogen come from?

Answer -

the Big Bang.

But here's the crucial bit.

The laws of nature themselves

tell us that not only can the Universe

have popped into existence like a proton

and have required nothing in terms of energy...

But also that it is possible

that nothing caused the Big Bang.

Nothing!...

Narrator: The explanation lies back with the theories of Einstein

and his insights into how space and time in the Universe

are fundamentally intertwined.

Something very wonderful happened to time

at the instant of the Big Bang.

Time itself began.

To understand this mind-boggling idea,

consider one of these -

a black hole floating in space.

A typical black hole is a star so massive

that it has collapsed in on itself.

It's so massive that not even light can escape its gravity,

which is why it's almost perfectly black.

Its gravitational field is so powerful,

it doesn't only warp and distort light

but also time.

To see how,

imagine a clock is being sucked into it.

[ Clock ticking ]

As the clock gets closer and closer to the black hole,

it begins to get slower and slower.

[ Ticking slows ]

Time itself begins to slow down.

Now imagine the clock as it enters the black hole.

Well, assuming, of course,

it could withstand the extreme gravitational forces,

the clock would actually stop.

[ Ticking stops ]

It stops not because it's broken

but because inside the black hole itself,

time doesn't exist.

And that's exactly what happened at the start of the Universe.

Hawking: The role played by time

at the beginning of the Universe is, I believe,

the final key to removing the need for a grand designer

and revealing how the Universe created itself.

Narrator: As we travel back in time

towards the moment of the Big Bang...

the Universe gets smaller

and smaller and smaller...

until it finally comes to a point

where the whole Universe is in a space so small

that it is, in effect,

a single, infinitesimally small,

infinitesimally dense black hole.

And just as with modern-day black holes

floating around in space,

the laws of nature dictate something quite extraordinary.

They tell us that here, too,

time itself must come to a stop.

You can't get to a time before the Big Bang

because there was no "before the Big Bang."

We have finally found something that doesn't have a cause,

because there was no time for a cause to exist in.

For me, this means there is no possibility of a creator

because there is no time for a creator to have existed.

Since time itself began at the moment of the Big Bang,

it was an event that could not have been caused or created

by anyone or anything.

So, science has given us

the answer we set out to discover,

an answer that took

more than 3,000 years of human endeavor.

We have discovered how the laws of nature,

acting on the mass and energy of the Universe,

started a process that would eventually produce us,

sitting here on our planet

pretty pleased at having worked it all out.

So, when people ask me if a God created the Universe,

I tell them that the question itself makes no sense.

Time didn't exist before the Big Bang,

so there is no time for God to make the Universe in.

It's like asking for directions to the edge of the Earth.

The Earth is a sphere.

It doesn't have an edge,

so looking for it is a futile exercise.

Hawking: We are each free to believe what we want,

and it's my view that the simplest explanation is

there is no God.

No one created the Universe, and no one directs our fate.

This leads me to a profound realization.

There is probably no heaven and no afterlife, either.

We have this one life to appreciate

the grand design of the Universe.

And for that, I extremely grateful.