All language subtitles for BBC.Everything.and.Nothing.2of2.Nothing.PDTV.XviD.MP3.MVGroup.org.eng

What is nothing?

It's an extremely, extremely
difficult question to answer,

because if you think about it,

wherever you look around you, there
always seems to be something there.

Things appear almost impossible
to escape from.

Even just trying to
imagine true nothingness

seems like an impossible task.

But this is more than just
a philosophical question.

I have here a box. What would happen

if I were to remove everything
I possibly could from inside it?

All the air, dust,
every last single atom,

until there was no thing left.

What, then, exists inside
the space in the box?

Is it really nothing?

You might wonder why this matters.

Well, emptiness is what makes up
almost the entire universe.

Even the atoms
that make up our bodies

and the physical world around us
comprise mostly of empty space.

This film tells the story

of how we've begun to understand
what is known as the void,

or the vacuum.

Emptiness, or simply nothing.

It's about reality
at the very furthest reaches
of human perception.

A place where the deepest mysteries
of the universe may be held.

This film reveals how,

using ingenious technology,

humans have transcended
their physical senses,

and found ways to understand
and probe the universe

at the smallest scales.

Today, we believe the void
contains nature's deepest secrets.

It might even explain
why we exist at all.

And that's because,
to the best of our knowledge,

the entire universe
appeared nearly 14 billion years ago

out of nothing.

For over 1,000 years,

our understanding of empty space
was defined by one man -

the Greek philosopher Aristotle.

To Aristotle, the concept of
nothingness was deeply disturbing.

It seemed to present all sorts
of problems and paradoxes.

He came to believe that nature
would forever fight against

the creation of true nothingness.

As he put it,
nature abhors a vacuum.

These words stuck for over 1,000
years, because after Aristotle,

people who attempted to make empty
space faced an uphill struggle.

It seemed nature was indeed
doing everything in its power

to stop them.

Well, the whole mystery
of nothingness

is contained inside
this simple drinking straw.

Let me demonstrate.
If I suck out the air
from the top of the straw...

..more air immediately rushes in
to fill the space left behind.

And even more weirdly,
if I block off the bottom
of the straw and suck...

..the walls of the straw
collapse in on themselves.

It's as though the universe
won't allow me to make nothingness.

And it gets even weirder.
If I take a sip of my drink...

..and pinch off the top,

then it seems nature
is so intent on stopping me

that even the law
of gravity is suspended.

So it's not hard to
understand why people believed

that it was impossible
to make truly empty space.

But there is
a very simple explanation

for why a straw behaves like this -

a reason that would
come as a profound shock
to the people who worked it out.

By the 17th century, some strange
exceptions were being found

to nature's abhorrence
of empty space.

And it was beginning to seem

like there may be ways of tricking
nothingness into existence.

The man who would finally
do what Aristotle thought impossible

was an Italian Jesuit
called Evangelista Torricelli.

Torricelli's experiment would,
for the first time,

create and capture empty space for
long enough to begin to study it.

This is how the experiment went,
with a tube filled with mercury

and a finger really
strongly clamped over the end.

The tube was then turned upside down

and then placed
into the bath of mercury.

At this point,
the mercury was released.

You can now see it dropping down.

And then it stops.

So I guess
the important thing is that...

that isn't trapped air.

We started with a tube
filled with mercury, and all
we did was we let it drain out.

But it doesn't drain out completely,
it reaches a level and stops.

Torricelli's experiments had not
only created an airless space,

it had also shown that the
atmosphere has a specific weight.

The reason my straw crumples
when I suck the air out

is because of the pressure of
the atmosphere that surrounds it.

But Torricelli's apparatus
was overcoming this

by using the extreme weight
of mercury and a rigid glass tube.

The level of mercury in his tube

was a measure of
the weight of the atmosphere.

The level is, of course, determined
by the weight of the mercury
on the one hand,

and the weight of the air
pressing down on the other.

And so the two balance out,
like scales.

They'd found a way
to weigh the atmosphere.

And Torricelli wrote
this fantastic phrase.

He said, "Noi viviamo
sommersi nel fondo d'un
pelago d'aria elementare."

"We live at the bottom
of an ocean of air."

Suddenly, the air really
was a substance.

But I guess the real mystery
for me now is, what's inside here?

Could this really be nothingness?

Indeed.

In revealing
that the air has a weight

and that it's pushing down on us all
the time, filling any space it can,

Torricelli had managed
to create an empty space,

a type of nothingness
that could now be studied.

Over 1,000 years of thinking
about the way nature worked

was beginning to crumble.

Medieval philosophy, much
influenced by Aristotle, supposed,

reasonably enough, that there is no
such thing as empty space in nature.

And yet here is
a pretty simple device -

a long, thin glass tube
with some liquid in it -

which is able to produce, says
Torricelli, an empty space,

thus showing that Aristotle
and his disciples are wrong.

How can you show that centuries of
philosophical tradition are wrong

just by doing a trick?

That didn't seem right at all.

But Torricelli was right,

and it would fall to philosopher
and scientist Blaise Pascal

to develop and refine his work.

As Pascal began investigating
Torricelli's ideas,

he discovered even more
peculiar properties.

In Paris, he carried a mercury
tube to the top of a huge tower

and recorded the mercury
dropping to a lower level
than it had been on the ground.

It seemed the pressure of the air
fell as you went higher.

Pascal's experiments would lead
to the realisation that the Earth

is cocooned in an atmosphere
that rapidly thins out
the higher you go...

..eventually becoming the cold,
silent expanse of space.

Torricelli and Pascal had begun
to unravel a profound truth -

nothing is everywhere.

Our Earth is merely
a tiny speck of dust,

floating through a vast expanse

of an utterly silent,
inhospitable void.

Nature doesn't abhor a vacuum.

A vacuum is nature's default state.

So what was this vast, empty space?

Now it was possible
to make it on Earth,

scientists became deeply curious.

What exactly were
the properties of nothingness?

After Torricelli
and Pascal's experiments,

many scientists became fascinated

with studying
the properties of the vacuum.

And they found some very odd things.

For instance, placing a ringing
bell inside it became silent,

you couldn't hear it
from the outside,

because, having removed all the air,

there was no medium
to carry the sound waves.

Most intriguingly, although
you couldn't hear the bell,

you could still see it.

This means light must be
travelling through the vacuum.

But how could it do this?

For those scientists carrying out
experiments with the vacuum,

there was just one
simple conclusion.

The vacuum wasn't empty after all.

The fact that
they could see inside it

meant that there still had
to be something left in there.

Just as air carries sound waves,

they believed there had to be
a medium carrying the light waves.

And whatever it was, it was proving
very difficult to get rid of.

The nothingness that had been
glimpsed by Torricelli and Pascal

now appeared to be a something -

a mysterious substance
which carried waves of light.

And if that this substance
existed in our vacuums on Earth,

it meant that it also
existed out there.

It appeared once again
that nothingness
could not exist in nature.

Everything in the universe
appeared to be sitting
within an invisible medium,

what scientists called
the luminiferous aether.

It was clear for many reasons,
many good reasons,

that light was a kind of wave.

But if light is a kind of wave,
what's it a wave in?

Sound waves are waves in air,
light waves are waves in
what came to be called,

from the early 1800s,
the luminiferous aether,

the light-carrying fluid
that fills all space.

If there's a fluid that fills all
space, if light is a wave,
nowhere is empty,

because light travels everywhere.

So at the very moment when
it seemed absolutely plausible

that there can be empty space,
it is obvious that there isn't.

And that there's this stuff
called aether that carries light.

The problem was that this aether

appeared to be so subtle
and so intangible

that it eluded
all attempts to measure it.

It wouldn't be until the end of
the 19th century that an experiment

would be built that was sensitive
enough to reveal the truth.

The experiment would take
place in the United States,

and Albert Michelson,
the scientist who conducted it,

would go on to become
America's first Nobel Prize winner.

From a young age,
Michelson had relished tackling

the particularly difficult
practical problems in physics.

He'd earned his reputation

by making extremely precise
measurements of the speed of light.

Having completed his work on light,
Michelson travelled to Europe

to spend some time amongst some of
the best scientists in the world.

And it was there that he became
fascinated with the topic

that everyone was talking about -
the mysterious luminiferous aether.

One idea in particular
captured his imagination.

It had been proposed that
if you could measure the speed
of light accurately enough,

it might just be possible

to actually deduce
the properties of the aether.

And this is how.

If there was an aether,
then as the Earth orbited the sun,

we should be able to detect
its presence.

It would be like sticking your hand
out of the window of a moving car.

You feel the rush of wind
as the car travels through the air.

Michelson realised that if this
picture of the aether was true,

then two light beams should travel
at different speeds on Earth,

depending on the direction they were
moving through this aethereal wind.

The difficulty was actually
in making such a measurement.

It seemed like
an almost impossible task.

The problem is this.

The speed of light is over
186,000 miles per second.

Now that's pretty nifty.

In comparison, the Earth
virtually crawls around its orbit.

So the difference in speeds
between those two light beams
would be tiny -

something like
one part in 100 million.

So the precision needed to get
any sort of meaningful result

was way beyond anything
that scientists thought
was possible at the time.

But not so the headstrong Michelson.

He began to work
his way round the problem.

He started to develop techniques
and precision instruments

that he believed would be capable of
unlocking the secrets of the aether.

From 1881, Michelson
was taking measurements,

and tweaking
and refining his apparatus.

But it wouldn't be until 1887

at the Case School of Applied
Science in Cleveland, Ohio,

that Michelson would finally
build a machine sensitive enough

to give him some definitive answers.

There he joined forces with
another scientist, Edward Morley,

to conduct what was to become
one of the most notorious
experiments in physics.

The original apparatus was set
in a solid block of sandstone,

and then suspended
in a bath of mercury

to remove any vibrations that
might affect the measurements.

It was incredibly
hi-tech and very expensive.

Think of it as an 1880s version
of the Large Hadron Collider.

OK, so here's how it works.
Light is emitted

from this source.

In the middle is something
called a beam splitter,

which divides the light
up into two parts.

Over here are two mirrors,

which reflect the light
back to the middle

where they recombine
at the beam splitter.

The light is sent down
to this detector. Now,

Now, because of the wave-like
properties of light,

you see
a very specific pattern here.

Basically, if the light
has travelled at the same speed
along the two paths,

then you see a bright spot
in the middle of the pattern.

So here's the really clever part.

Michelson and Morley reasoned

that if the Earth really was moving
through a stationary aether,

the experiment should behave
in a very different way.

Let's look at what happens when we
simulate the effect of an aether.

The light leaves the detector

and gets split.

Now here's the key.

The light that travels against
the aether and back again

covers this journey
in a different time

to the light travelling
across the aether.

This means that when
the light waves recombine,

they now interfere with each other.

This interference
means that the image

will have a dark spot at its centre.

See this, and you know that
the void must be filled

with a stationary medium through
which the Earth is moving.

Of course I can't be sure exactly

what was going through the minds
of Michelson and Morley

as they began their experiment,

but it is a safe bet that, given
the scientific consensus at the time,

they were convinced
that the aether really existed.

So they would have been sure
that they would have found light

travelling at different speeds as
it moved in different directions.

But it didn't.

No matter how they
rotated their apparatus,

they always found light
travelled at the same speed.

Michelson and Morley had gained an
extraordinary and accurate result.

But the idea of the
luminiferous aether was so ingrained

that they believed simply
that their experiments had failed.

So what is going on?

Why didn't Michelson and
Morley's experiment reveal
the result they were expecting?

How could light always be travelling
at the same speed?

Well, the answer is simple.
The aether doesn't exist.

No matter what light is doing,
how it is travelling,

it doesn't need to be carried
along by this mysterious stuff
that pervades the vacuum.

So how does light
move through empty space?

Well, by the end
of the 19th century,

light was known to be in fact

a combination of fluctuating
electric and magnetic fields.

But it would take the genius
of Einstein in 1905

to reveal that this picture of
light doesn't need an aether.

He showed that
it has the weird property

of being able to propagate
through completely empty space.

So the message from the failure
of Michelson and Morley's
experiment is this -

there is no aether.

Maybe the vacuum is really empty.

If only it were that simple.

Almost as soon as Michelson
and Morley had revealed,

by accident, that you
really could have nothing...

..scientists began to discover some
very weird properties of nature.

In the 100 years that followed
Michelson and Morley's experiments,

physics and our understanding
of the vacuum

has been totally transformed.

But what drove this huge shift
was not simply scientific curiosity.

But the fact that in
the late 19th century,

the vacuum and its many
applications had become big business.

Industry was finding
ever more ingenious ways

to make money out of nothing.

Understanding and harnessing
the vacuum turned out

to lead to a wealth
of new technologies that
we just take for granted today.

Everything from
the light bulb to the television

were only made possible

because they could contain
within them small volumes of vacuum.

The filament inside a light bulb
can glow for long periods

because it is contained
within a vacuum.

Expose it to air and it would
simply burn out in seconds.

As cities around
the world began to electrify,

the demand for
light bulbs grew massively.

The engineers became ever more
skilled at creating cheap,
efficient vacuums.

This technology would give rise
to a huge range of gadgets -

everything from the valves
in radios and early computers

to the television.

But all the
technological innovations
that came from harnessing the vacuum

would pale into insignificance
when compared to what scientists

would soon find out about
the fundamental nature of reality.

Because vacuum technology
was getting so much cheaper,

and more efficient,

scientists all over the world could
use it as a tool for research.

In empty space, nature's tiniest
constituents could now be studied

without interference
from the contaminant-filled air
of the outside world.

This revolutionised physics.

Because of the vacuum,
X-rays were discovered in 1895.

The following year, the electron
was identified for the first time.

And in 1909, Ernest Rutherford
would use vacuums

to help reveal
the strange structure of the atom.

These discoveries were all feeding
into a radically new picture

of the way nature works at its
smallest and most fundamental level.

It was a theory that would come
to be known as quantum mechanics.

And the submicroscopic world it
describes behaves very differently

to the world we are used to.

This is a world where,
against all common sense,

it seems impossible
to ever truly have nothing.

This is the classical world,

action and reaction.

Cause and effect.

It is sensible,
certain and knowable.

But the quantum world soon revealed
itself to be very different.

There was one discovery
that was particularly troubling

and it's known as
Heisenberg's Uncertainty Principle.

In everyday life
we are used to doubt, to uncertainty.

How can we be sure that
something is this way or that way?

Well, it turns out that nature itself
is based on indeterminacy,

in uncertainty.

The world of quantum physics,
the microscopic world,
is a world of uncertainty.

It's a world where you can never
be sure of what is going to happen.

Not because your measurements are not
good enough, simply because,

at a very fundamental level, nature
itself is based on uncertainty.

OK, I would like to
get across the essence of
Heisenberg's Uncertainty Principle.

I'm going to use
a non-mathematical analogy.

We have to be careful here -

it is just an analogy so
we shouldn't push it too far.

I have here two
identical memory sticks.

On the first one
is a high-resolution image.

It is a picture of me
having a game of pool.

We can see it is very detailed.

In fact, I can zoom in...

..even quite closely
onto the pool ball.

And you see,
even at this magnification,

I can still see the precise
position, I can see the edges
of the ball very detailed.

But what I don't know is
how fast the ball is moving

or what is going to happen next.

Now, on the second memory
stick is another file.
It's a very different kind of file.

It is a movie.

The important thing to note
is that the file is the same size

as the high-resolution image.

Now, have a look at this.

Now we can see the whole movie
playing out. It is the same scene,

but you can see
all the balls moving.

But if I zoom in on some detail...

..very quickly the balls
become fuzzy and blurred.

So for the same amount
of information,

although I've gained knowledge
about how the balls are moving,

I've lost information
about their exact positions.

So with the more I know
about where something is,

the less I know
about how it is moving.

In the quantum world,

I cannot at the same time
know both these quantities exactly.

Unfortunately,
there is no way around this.

Heisenberg showed in his mathematics

that this is in an inescapable
feature of reality at this scale.

OK, so what has all
this quantum weirdness

got to do with nothing?

Well, you see,
Heisenberg's Uncertainty Principle
can be expressed in a different way,

in terms of a balance between two
other quantities - energy and time.

Now, this is going to sound
quite complicated,

but it's very important,
so I'm going to try and explain.

You see, if I were to examine

a small volume of empty space
inside this box, then I could

in principle know how much
energy it contains very precisely.

But, if I were able
to slow time down,

things would start
to get very strange.

OK, so we are now looking
at a tiny interval of time
that has been stretched out.

Heisenberg's uncertainty principle

tells us that because I'm looking
at a smaller interval of time,

I've lost precise information
about the exact energy in the box.

If I could examine
an even smaller interval of time,

and an even smaller volume
inside the box,

then Heisenberg's equation
suggests something
truly bizarre could happen.

I will be so uncertain about
how much energy there is in that
part of the box,

that there is a chance
it could contain

enough energy to create particles
literally out of nowhere...

..provided that somehow
they went away again very quickly.

Heisenberg's uncertainty principle
seemed to suggest that

in truly tiny amounts
of time and space,
something could come from nothing.

But then what?
If particles could pop into
existence, where do they go?

Why don't we see these
particles appearing all around us?

The vacuum, contrary to what
one normally expects from the vacuum,

is alive.

It's alive with what physicists
call quantum fluctuations.

In the vacuum, little packets
of energy appear and disappear

very, very quickly.

This is perfectly allowed
by the laws of physics.

It's all allowed but it has an name,

it is called Heisenberg's
uncertainty principle,

which tells us that you can

borrow energy from nothing, so long
as you pay it back quickly enough.

The vacuum is alive.

Bizarre though these ideas seem,
they are, I promise you,
fundamental to our universe.

To see how this can be,

our story of nothing
takes us to one of the most

gifted and oddest characters
in the whole history of physics.

Behind me is Bishop Road
Primary School in Bristol

and almost 100 years ago,

it was attended by two students
who were destined for greatness.

One of them, Archibald Leach,
would go on to conquer Hollywood,

becoming better known
as Cary Grant.

The other was a quiet, shy
and rather intense boy two years
younger than Grant,

who would become one of
the greatest scientists
Britain has ever produced,

the theoretical physicist
Paul Dirac.

Even by the standards
of theoretical physicists,

Dirac was a very queer bird.

He was not someone
you'd go for a beer with.

Intensely focused,

man of extremely few words,
very, very little empathy

and someone of rectilinear thought.

These personality traits were key
to Dirac's genius,

but they often resulted
in difficult or awkward

social situations with his peers.

Even in casual conversation, Dirac
would never speak unnecessarily.

He'd often leave these long
pauses in between sentences while

he worked out the most precise and
concise way of expressing himself.

Friends had jokingly coined
the term a Dirac, which stands for

the smallest number of words it
is possible to speak in one hour,

while still taking part
in a conversation.

It is a sort of unit of shyness.

Dirac's unusual personality
had its roots

in a difficult
and troubled childhood.

But from a young age, he had
found solace in the classroom.

In particular, he excelled at both
mathematics and technical drawing.

This was something that
cultivated his visual imagination.

In maths classes, he was
looking at mathematical symbols.

He was looking at similar things,
but in a geometric way in
his technical drawing class.

It is very, very suggestive of the
way he looked at physics later on

because he always stressed that
he was pre-eminently a visualiser.

He was someone who had a geometric
look at physics.

He was not interested per say
in mathematical symbols.

Rather he wanted a visual sense of
what was going on in the mathematics.

Dirac continued his visual training,
doing a degree in engineering

before go to Cambridge
to study mathematics.

It would be here that
Dirac would begin to unravel
the deepest mysteries of the vacuum

and uncover what was
really going on in empty space.

But his insight sprang from a
seemingly unrelated difficulty.

By 1928, physics was
struggling with a big problem.

The two most important theories

that described
how the universe worked
didn't agree with each other.

On the one hand, you had Einstein's
special theory of relativity

encapsulated
in the famous equation E=mc2.

It was a beautiful,
simple and elegant theory

that describes the behaviour of
things close to the speed of light.

On the other hand, you had
Planck's discovery of the quantum

and the revolution that followed
describing the bizarre rules
of the very, very small.

The problems arose
when trying to describe situations
where things were small enough

for quantum effects to be felt,

but travelling fast enough for
special relativity to be important.

Specifically, there were
huge problems trying to describe

the electron, a tiny particle
whizzing around inside an atom.

If both of these theories were true,
then they should be able to be used

together to give a mathematical
description of the electron.

But what if this couldn't be done?

What if quantum physics and special
relativity couldn't be married?

This would mean one or other
of these two cornerstones
of physics had to be wrong.

A way had to be found for the two
theories to be married together.

It would be Dirac
who would achieve this.

Dirac's unification of the
special theory and the rules of
the quantum world

would rank as one of
the greatest mathematical
accomplishments of the 20th century.

And it would lead inadvertently
to a radical new picture of nothing.

To get a non mathematical sense
of what he did, and how he did it,

I've come to the cinema to see one
of Dirac's favourite films,
2001 A Space Odyssey.

Understanding
why it appealed to him

helps give us an insight
into how he managed to
solve this great problem.

If you look at 2001, it was, as
Kubrick has said, a demonstration

that you could make a really good
movie script without words

but with a power of
the visual imagery.

Now, that in some ways
is very closely analogous

to Dirac's a theoretical physics

because, for him, what was central,
were the mathematical equations.

And more over, he had a visual
sense of what those equations meant.

The abstract images of 2001
appealed to Dirac

because they captivated
his brilliant visual imagination.

It was this highly developed
and unusual way of thinking,

honed in his schooldays,
that would enable him in 1928

to visualise a unique
way of describing the electron.

It was a description that
finally managed to unite Einstein's

special theory of relativity
and the weird world
of quantum mechanics.

Today, it's known simply
as the Dirac equation.

It may look like a small
collection of symbols,

but to a mathematician this
equation is profoundly beautiful.

A complex and symmetrical
synthesis of mathematical ideas,
expressed with stunning clarity.

This is the commemorative
plaque at Bishop Road,
Paul Dirac's primary school.

And on it, his famous equation.

Within these few symbols lie
profound truths about the universe.

But don't be deceived by
its apparent simplicity,

think of this equation as the tip
of a giant mathematical iceberg.

Each of these terms relate to
entire branches of mathematics

and the particular
relationships between them.

Beneath this equation,
are mathematical ideas that

have been developed and honed by
many, many other great individuals.

If you think of a poem, you can
think of it as the most supercharged

kind of language,
the way you compress meaning

into a very, very
brief area on the page.

Dirac was producing equations
that had that kind of concision

and you can then unpack them,

just as you re-read a Shakespeare
sonnet and see more and more
in it, more and more elegance.

Same with the Dirac equation,
you find an equation there

you can keep finding things that
were not obvious on first reading.

In fact, Dirac once said that the
equation was smarter than he was

because it actually gave more stuff
out than he put into it.

There was one particularly
odd thing the equation seemed
to be saying to Dirac.

Something that would redefine
the concept of empty space forever.

In his description of the electron,
Dirac had been forced to use a
collection of four equations

represented by the symbol gamma,

in order to make special relativity
and quantum mechanics fit together.

But the need for
four equations seemed strange.

To Dirac and other
physicists in the 1920s, the first
two were quite recognisable.

They described the behaviour
of an electron as it had
been observed in the laboratory.

But the second two
were very strange.

They seemed to be saying
there was some other type of
electron that could exist.

One that had
never been seen before.

So, this is the normal
world we are familiar with.

And here, scaled up
many, many times

is a regular electron of the type
contained within

the trillions of atoms
that make up this table,

me and everything else
in the universe.

Dirac realised that
these mysterious new elements
in his equation

predicted the existence
of a strange new kind of particle.

In some ways, just like the
electron, and yet at the same time
very, very different.

Dirac gradually became convinced
that the new parts of his equation

were describing something

that could be thought of
as an anti-electron.

In many ways, it was like
the mirror image of an electron,

having opposite properties like
electric charge.

And, in principle an anti-electron
could form part of an anti-atom,

and many anti-atoms
could fit together

to make an anti-matter table,
or even an anti-me.

But the weirdness didn't end there.

Dirac realised that if things and
anti-things ever met each other,

they would instantly annihilate,

turning all their mass
into energy...

EXPLOSION

Disappearing completely.

Here, finally was the answer
to the riddle of empty space.

Heisenberg's uncertainty principle
had suggested that matter could

pop into existence for
incredibly short periods of time.

Now, Dirac had provided
the mechanism

by which matter could
be created out of the vacuum...

..and just as quickly,
disappear again.

So, let's take another look
at our box.

Whenever a particle pops out
of empty space,

so simultaneously
does its anti-particle.

Although this sounds
completely ridiculous,
let me assure you it is true.

So, whenever you try to remove
everything you can from empty space,

it's still always awash
with all these fluctuations.

Within nothingness, there's
a kind of fizzing, a dynamic dance

as pairs of particles
and anti-particles

borrow energy from the vacuum
for brief moments

before annihilating
and paying it back again.

Dirac's theory of the electron
and the idea of anti-matter

gives us a completely
new picture of the vacuum.

Before you could think about the
vacuum as empty space, so to speak.

relativity had said,
you don't need an aether,

so the picture was
of the vacuum being empty.

But when you bring relativity and
quantum theory together

then you have for certain,
this notion of electron
and anti-electron pairs

just appearing out of the vacuum.

So you can think of these pairs just
sprouting all over the place
in the vacuum.

So, the vacuum goes from
being nothing

to being a place absolutely teeming
with matter, anti-matter creation.

Dirac's ideas about empty space
were refined and developed

into what is known today as
quantum field theory.

And these strange
fleeting things within nothing

became known as
virtual particles.

So it seems, nothingness
is in fact a seething mass
of virtual particles,

appearing and disappearing

trillions of times
in the blink of an eye.

I've come to
Imperial College London

to see the effects of
these virtual particles myself.

Thanks to a brilliant experiment
by an American scientist
called Willis Lamb,

we now have a way to
conclusively show

there is activity
within apparent nothingness.

But in order to glimpse it,

you have to peer deep
within a single atom

and amazingly Lamb found
an ingenious way to do this.

So, what did Lamb do?

Well, his experiment relies on
the quantum rules of the atom.

Within atoms, electrons have very
specific, discreet energies

in the way
they orbit around the nucleus.

His experiment showed that if the
vacuum really was full

of these hidden fluctuations,

then these would cause
the electrons' orbit

to wobble ever-so-slightly.

Think of it as an analogy
as though the electron is a plane

flying along
and hitting turbulence

forcing it to move up
to a slightly higher altitude.

So this is how
the experiment works.

Contained within
this vacuum chamber
are a small number of atoms.

While Lamb used microwaves in
his original experiments,

in this version,
the team at Imperial are
using lasers to probe the electrons.

Now, if you think this all
looks very complex, just remember

how small a measurement it
is we are trying to make here.

This apparatus has to be sensitive
enough to pick up minute changes

in the behaviour of something
that is itself, extremely tiny.

Imagine we could scale up
the wobble in electron
that's being measured

to the size of this apple.

That would mean this vacuum chamber
behind me, would scale up to
being a trillion miles in size.

The vacuum chamber
would be something like

100 times the size
of the entire solar system.

It would take light about 40 days
just to travel from the top
down to the bottom.

So, what is going on in there?

OK, so let me first fire up the
laser in the experiment behind me.

What this monitor will show us is
exactly what's going on
inside the vacuum chamber

down at the minutest scales.

Now, look at this peak
that's appeared.

BUZZING

It may not look very exciting,

but it's telling us
something really remarkable.

This is measuring the amount
the electron is being wobbled about
by the vacuum itself.

If the vacuum were truly empty,
this peak wouldn't exist,

we'd just get a flat line.

What this is telling us
is that however hard we try

to remove everything we can
from space, we can never
get it truly empty.

Everywhere in the universe,
space is filled with this vacuum

that has a deep,
mysterious energy.

But it doesn't end there.

When using the mathematics laid out
by Heisenberg, Dirac and others,

you can calculate the amount
the electron should be affected.

When you run the real physical
experiment, the answer you get

matches the theory
to one part in a million.

The theory of quantum mechanics
is the most accurate

and powerful description of
the natural world that we have.

But there's a much more
dramatic way

in which we can see the effects
of these quantum fluctuations.

And that's because
they're written into the stars.

Today, our best theories tell us

that as the universe
sprang from the vacuum,
it expanded very rapidly.

And this means that the rules
of the quantum world should have

contributed to the large-scale
structure of the entire cosmos.

When our universe first came
into existence, it was many times
smaller than a single atom.

And down at this size it's governed
not by the classical rules we're

familiar with, but by the
weird rules of the quantum world.

This is for me, one of the most
profound and beautiful ideas
in the whole of science.

That it's quantum reality that has

shaped the structure of the
universe we see today.

Our universe is just the quantum
world inflated many, many times.

Nothing really has shaped
everything.

And what's more,
we now have a way to see this.

This is a picture
of the first light that
was released after the Big Bang.

Think of it
as a baby photo of everything.

This incredible picture was taken
by a team of researchers at NASA

led by Professor George Smoot.

This is like taking a

picture of an embryo that's 12 hours
after conception,

compared to taking a picture

of a person who is 50 years old.

It's in the same perspective.

And 12 hours, you may have two cells,
this is very early and yet
we are seeing what's equivalent

of the DNA, the blueprint for how
the universe is going to develop.

With the help of highly
sensitive satellites,

George Smoot and his team
were able to study this image

of the embryonic universe
in amazing detail.

And when they did, tiny variations
in its temperature were revealed.

It soon became apparent that the
tiny differences in temperature

are in fact the scars left by the
quantum vacuum on our universe.

EXPLOSION

These irregularities
created in the first
moments of existence

by the teeming quantum vacuum
meant the matter of the universe

didn't spread out
completely evenly.

EXPLOSION

Rather, it formed vast clumps
that would evolve into

the galaxies
and clusters of galaxies
that make up the universe today.

The application of quantum physics
to cosmology,

to the universe as a whole

was revolutionary.

It really changed
our entire perception

of the evolution of the universe,

because it turns out
that quantum physics provides
a natural mechanism

through quantum fluctuations

to see into the early universe
with small irregularities that
would later grow to make galaxies.

The thought is really overwhelming,
the idea that an object

with billions of stars
like the Milky Way
began life as a quantum fluctuation,

what we call a fluctuation
of the vacuum,

an object of sub-microscopic scales,
it really is mind boggling.

It now appears as if the quantum
world, the place we once thought of

as empty nothingness has actually
shaped everything we see around us.

What happens is, something
that was a small fluctuation,

a tiny quantum fluctuation,
becomes our galaxy.

Or becomes a cluster of galaxies
because there are lots of
quantum fluctuations,

so it answers one of the
questions we have -

why are there 100 billion galaxies
in our viewpoint?

Well, in a drop of water,

there's many more than 100
million quantum fluctuations,

in an atom there's that many,
the vacuum has all of this
bubbling going on all the time.

The teeming, seething activity
of the vacuum, of nothing,

and the quantum fluctuations
within it...

..were the seeds, seeds which grew
into the universe we see today.

This idea
gives rise to one final revelation.

Today, our best theories
about the cosmos tell us

that at the beginning of time,
the universe sprang from the vacuum.

Creating not only vast amounts of
matter, but also the strange stuff

that was predicted by Paul Dirac...

..anti-matter.

But the universe we see today
is made of matter,

nearly all of the anti-matter
seems to have vanished.

EXPLOSION

According to common theory,

the Big Bang produced equal
amounts of matter and anti-matter.

But as the universe cooled down,

matter and anti-matter annihilated
almost perfectly, but not quite.

For every billion particles
of matter and anti-matter,

one was left behind.

The matter and anti-matter that
annihilated to produce radiation

gave rise to the heat of
the Big Bang

that we see today in the form of
the microwave background radiation.

The little particle that was
left behind, for every billion

that annihilated is what makes
galaxies, stars, planets and people.

So, we are simply the debris
of a huge annihilation

of matter and anti-matter
at the beginning of time.

EXPLOSION

The leftovers of
an unimaginable explosion.

All these insights have arisen

from simply trying to understand
what nothing really is.

What we once thought of as the void

now seems to hold within it,

the deepest mysteries
of the entire universe.

In the 400 years or so since
Torricelli and Pascal

began exploring vacuums
here on Earth,

we've begun to understand in
ever greater detail the world's at
the very limits of our perception.

And in doing so, we've uncovered the
strange truth about reality itself.

There's a profound connection
between the nothingness

from which we originated

and the infinite
in which we are engulfed.

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