All language subtitles for How Small is the Universe BBC Horizon 2012 720p HDTV_Subtitles01.ENG

Astronomers have long tried to
understand our place as tiny specs

in the vastness of the universe.

But there is another expanse of the
universe to explore,

a bizarre realm
in which we are giants,

the weird world of the very small.

This is a journey
into the heart of matter,

a journey down the biggest
rabbit hole in history...

It's perfectly possible that in the
high-energy end of our data,

right now we are occasionally making
miniature black holes.

..a journey smaller than you can
see, smaller than an atom,

where nothing is what it seems...

The more fundamental things are,

the nicer it is to look inside them.

..into a wonderland which seems
far removed from reality...

Gravity is leaking
into the extra dimensions.

..down to the very smallest
structure of the universe.

We should expect space time to be not
smooth as we presently imagine,

but more like the foam
of a cappuccino.

The journey
to find the smallest thing

may take us into another
universe altogether.

But then of course,
when you're down to this scale,

you may have the whole
universe in your hand.

And at the bottom
of the rabbit hole,

we may find that our universe
is just one of many.

On top of an extinct volcano
in the Canary Islands

a strange telescope called
MAGIC stands guard.

It's on a ten-second stand-by

to respond to the most violent
explosions in the cosmos.

With its laser-aligned panels,
it is detecting the fallout

from cosmic rays that have travelled
half way across the universe.

And it's helping physicists answer
an eternal question.

Well, at the end of the day, the
question comes up, why do we exist,

and not only we as mankind,
but why does this planet exist,

the solar system, the universe?

If you want to know why the universe
exists, you need to look,

not to the very big,
but to the very small.

And it turns out there need to be a
very small number of parameters

very finely adjusted for the universe
to be as it is

and for us to sit in this universe,
to be able to observe it.

So I think this tells
why it's important to understand

how the laws of nature work.

And the strangest thing about MAGIC,

is that it's not really
a telescope at all.

It's the eyepiece of the
biggest microscope in the world.

It's just one of the incredible
tools scientists have developed

in their ongoing search for the
smallest thing in the universe.

Look at that!

The nucleus and the electrons going
around the atom.

The exploration of the most distant,

unreachable territory
in our universe is challenging

the minds
of our greatest scientists.

Very nice. This is very complex,
very complicated.

Am I getting there? Aargh!

As you look smaller and smaller,

no-one knows if there
will ever be an end.

Well, with me you'll see the more
determination to find the next layer.

I'm going to need
a bigger collider soon.

So we split, even split the nucleus.

The hunt for the smallest thing
in the universe

is challenging our understanding

of the very nature
of space and time.

Yes. This is it.
This is the smallest piece.

That is the smallest thing, isn't
it?

Nice analogy!

The search for the smallest building
blocks of the universe

is one of the oldest in science.

For almost 1,000 years, this
medieval cathedral has looked over

the streets of Aachen in Germany,

an enduring monument
of stone and glass.

But if you look really,
really closely,

all is not what it seems.

Professor Joachim Mayer is a man
with a unique view on the world.

He sees the bizarre changes
that come about

when you view the world in terms

of the building blocks of stuff -

atoms.

Where you or I might see red,
he sees gold.

There are always
two parts of your brain.

If you look, if you come in as a
human being

but as a scientist as well,

you are stunned by what people have
built in these medieval times.

And then you ask yourself
what kind of materials did they use?

If you look for example at these
glass windows, it's very well known

that actually nanotechnology is used
in some of the colours, for example

gold nanoparticles actually, produce
the most durable red colour

which can be produced.
And it's still a miracle to us

how in these ancient times,
you know, the people found out

that this is the most efficient way
to produce a red colour.

The red is just an illusion caused
by the massive difference in scale

between the tiny clumps of gold
atoms and us -

the giants who see red.

It's one of the reasons

scientists are obsessed with
reaching the smallest scales.

Things don't just get smaller,
they change.

Scientists have thought
for a long time

what are the smallest building blocks
of our matter,

and you can see
beautiful matter around us.

But just how small are these
building blocks?

If we start on the
familiar scale of a human

and zoom in ten times closer,

we get to the size of a face.

Magnify by ten once more, and we are
looking at the iris of an eye.

100 times closer
and we can see a human hair,

magnified 10,000 times.

Microscopes have unveiled a world

smaller than the wavelength
of light.

But the ability to see individual
atoms has, until recently,

been a dream.

As microscopes have got
bigger and more powerful,

they have allowed us
to peer ever smaller.

It was the ancient Greeks who first
dreamed up the idea of atoms.

100 years ago,
scientists proved they exist.

But it's only in the last ten years

that we've actually
been able to see them.

And now, behind these doors,

Joachim Mayer has a machine that
gives us the best possible view.

MUSIC: "Also Sprach Zarathustra"
by Richard Strauss

It looks like a giant coffee maker!

So this is our new PICO instrument,

which has been installed
about a year ago.

And with its special new corrector
for the chromatic aberration,

is really a very unique machine which
really offers us new possibilities.

I think with its new capabilities,
we consider it

as the best electron microscope
in the world.

Being the best electron microscope
in the world,

PICO is very sensitive
to its surroundings.

Even a person's body heat
would disturb it,

so PICO has to be operated remotely.

And, safely isolated from humans,

PICO is able to unveil the secret
world of the very small.

We start our investigations at a
very small magnification,

which is equivalent
to the highest magnification,
which you can actually reach

with a light microscope.
At this magnification,

the diameter of a human hair would be
about that size.

And now we can in magnification

go at least a factor of 1,000 higher.

And now we start
to see the structure,

actually these black dots are
individual gold nanoparticles.

And now you can see
the individual atoms

as they appear
in this individual nanoparticle.

So we see individual atoms
aligned in the structure.

It's hard to imagine just how small
these dots of matter really are.

But consider
that each of us contains

about seven billion,
billion, billion atoms.

That's more than the number of stars
in the entire universe.

PICO is, quite simply, the most
powerful microscope in the world.

After magnifying things a
billion times, we can actually see

the individual atoms that make up
everything in the universe.

This is the smallest thing
we can see.

It may well be the smallest thing
we'll ever be able to see.

These atoms look reassuringly like
what you'd expect -

solid round balls of stuff.

But this is merely an illusion.

If you want to find out what an atom
really looks like,

you need a whole new way of looking.

Professor Andy Parker
is trying to find things

smaller than anyone has ever found.

Well, the way to look inside an atom

is to fire something at it
very fast,

and if you hit it hard enough it you
can break it into little bits.

He's using the most expensive
experiment

in the history of physics,

one he helped design.

At 17 miles long, and buried
100 metres underground,

it is the biggest, and most famous
particle accelerator in the world -

the Large Hadron Collider.

The ring goes right over behind
the apartment blocks there,

and then it goes five miles
in that direction,

roughly to the horizon,

it comes round under the base of the
mountains to here,

and it sweeps back round,

past those buildings there
and back to point one.

But once you start looking inside an
atom, nothing is what it seems.

People always imagine atoms
as billiard balls,

they've seen pictures of atoms
as billiard balls

or with a little electron going
round quite a big nucleus,

and this is
a completely false picture.

If you blew up an atom to the size of
the Large Hadron Collider,

so it would be five miles
in that direction...

..all around there on
that piece of landscape...

..then the nucleus would be
about ten centimetres across,

about the size of this tennis ball.

So all the mass, all
the weight of the atom

is condensed into
this tiny little nucleus,

and the whole space around it is
empty, apart from these few electrons
buzzing around.

The illusion of solidity

comes from the fuzzy cloud
of charged electrons.

But on their own,

they weigh virtually nothing
and occupy no space.

You need to go
a 100,000 times smaller

to get to the nucleus - a fizzing
ball of protons and neutrons.

The challenge here at the LHC,

is to look inside the protons
by smashing them to pieces.

It's brute force
and ignorance really.

You are taking two things,
which are very, very small,

you don't really know what's inside
them to start with,

and you hit them together
as hard as you can

and they smash into tiny fragments
and since you really don't know

what the elaborate structure is
inside, it's kind of like

colliding two clocks together
and then sweeping up the mess

that you get and trying to
figure out how the clock works.

And you can't do it in a subtle way.

There's no screwdriver
to take a proton to bits

and there's no plan of what's inside

so you have to hit them very hard,
then the fragments come flying out

and from that we can try
and work out,

how all the cogs and gearwheels fit
back together to make a proton.

The debris
from the proton collisions

is detected by a vast
machine called ATLAS.

Everything interesting happens
at the centre,

that's where the particles collide.

This engineering mock-up shows just
one section of the real machine.

And the sensitive instrument at its
very heart is the part made by Andy.

So I'm in the middle
of the mock-up of ATLAS,

and this is where
all the action happens.

The beams would come in from both
ends through the centre here.

This would of course be filled
with detectors, but the beam pipe

would run right through the centre
and the particles, which are

travelling in vacuum at almost the
speed of light, collide head on

just here, and do their stuff and
then all the debris comes flying out

and it flies
through the detector layers...

..and that's the debris that we use
to reconstruct the collision

that happens right here
in the middle.

And what you find when you smash
a proton to pieces,

is that it too is
largely empty space.

It is made of three tiny fundamental
particles called quarks.

But to reach the size
of a quark we have to zoom in

1,000 times smaller.

Some of the earliest machines used
to probe the atom

were bubble chambers, that produced
exquisite pictures

of the heart of matter.

What you see here is a sudden
explosion of particles from nowhere

in the liquid of the bubble chamber
and that is because

a neutrino has hit an atomic nucleus
there and smashed it to pieces,

and we see the particles flying off.

And that's anti-matter.

That's matter and anti-matter being
created from pure energy.

Very, very beautiful image.

So this is the map or a part of the
map, of what nature can do.

So it's part
of the map of the universe.

But now, after 80 years of smashing,
the map is complete.

In the summer of 2012
scientists at the LHC,

announced the discovery of the
famous Higgs particle.

It's the final piece of what's
called the Standard Model -

a set of 17 fundamental particles

including quarks and electrons

that make up everything we know.

But for physicists like Andy

it's not the end of the story.

Everyone's heard about the Higgs

but the story goes much beyond that.

In fact my main interest
is beyond the Higgs.

Like any great explorer,
Andy is not satisfied

that this is the end of the journey.

There may be plenty more
to discover.

OK so we're in the ATLAS
main control room,

where the experiment crew,
shift crew here
are sitting taking data today.

This is live data
coming from the detector -

collisions that are happening now.

Collisions are happening
40 million times every second.

And as the energy
of the collisions increases,

Andy will be able to look
on smaller and smaller scales,

even delving inside the so-called
fundamental particles.

Fundamental particles is a myth,
I think.

It looks at the moment

as if quarks and electrons
are point-like particles.

We can't see any size to them
but that is just because

we haven't been able to measure very
short distances around them.

What I'd like to see
is what's going on inside them.

So we're looking
for the innards of the quarks

by smashing them together
as hard as we can.

In the search for the smallest piece
of the universe,

part of the problem
may be knowing when to stop.

Each new layer
reveals great secrets.

But does this search have an end?

Or within every small thing,

is there another...

..and another?

Perhaps the best known of all the
fundamental particles

is the electron.

It underpins
much of our modern lives,

from computers to street lights
to televisions.

But for theoretical physicist
professor Jeroen van den Brink,

the electron might not be as
fundamental as we think.

The more fundamental things are,

the nicer it is to look inside them.

Physics it's always that
something appears to be fundamental,

and just because we believe it's
fundamental we take the next step

and try to look what's inside it.

Jeroen's idea was that, rather than
smashing electrons into pieces,

he could find a different way
to split its properties...

the very properties
that make it so useful.

So the electron has three
fundamental properties,

charge, spin and orbital
and theoretically

it's definitely possible to split
those three parts of the electron.

If you do the mathematics

there is no problem in doing that.

If you do the quantum mechanics,
it's completely allowed.

So in principle
you can split the electron,

at least you can do it on paper.

If you want to want to do it in
practice, you need this...

Watch your head here.

..the Swiss Light Source,

a million watt light bulb.

This is an in vacuum undulator.

The Swiss Light Source is in fact
the Swiss X-ray Source.

We have digital BPM systems.

Inside the ring, under the care of
Dr Andreas Ludeke,

a beam of electrons creates the
ultimate X-ray laser.

This is a superconducting cavity.

It's one of the most powerful,
highly focused, narrow X-ray beams

in the world.

We have a high intense magnetic
field in the middle.

The perfect tool for probing down
to the size of an electron.

Jeroen's partner
in electron splitting,

the man who devised
and runs the experiment,

is Dr Thorsten Schmitt.

So here we are
in the so-called optical hutch,

where all the crucial
optical elements -

mirrors which are optimized for
X-rays and which are used

for shaping the beam quality
are sitting.

I can see it here. Yeah.

So when I come here I go to the
equipment, I look at it,

I admire it and then I go back
and sit behind a computer

or take my pen and paper
and start to do the mathematics.

I do not really understand what the
stuff out here is exactly doing

and I believe, I'm sure Thorsten does
and they do the experiments.

We have X-rays, which are coming in
and hit a sample,

and we will then in the end analyse
the X-rays, which are re-emitted

or scattered off from the sample.

When the X-ray beam strikes,

the electrons split into new
quasi-particles.

These particles, called spinons,
orbitons and holons,

carry the properties
of the electron,

and can travel off
in different directions.

This is actually the picture that
tells the whole story.

The most important part is here,
this red part,

and what's important
is that it's wavy.

And this waviness tells us that what
happened in this experiment

is that the electron was
split into spinons and orbitons.

So this is the picture

that is the experimental proof
that the electron has been split.

Are you proud
of that picture?

I'm very proud of the picture.

So the electron can be split into
these three different particles,

but, really, what can you do with
those particles when you have them?

I don't have a good answer to that.

It's just cool to make these,
make this electron that is so

fundamental, that's so part...
That's the first fundamental particle

that was discovered, to see it split
into its three different parts.

That's what I like
about the experiment.

The electron has, in one sense,
been split in three.

But it's a measure of just
how weird things are down here

that it's still considered
to be fundamental.

Down at this scale,

we just have to accept that
the rules become deeply strange.

And if we reach down even further,

we may have to throw out
the rule book altogether.

Back at the LHC,
far beyond the Higgs,

smaller than the innards of a quark,
Andy Parker believes ATLAS

could reveal something that, at this
tiny scale, shouldn't really exist.

So this great big building here
is at the top of the ATLAS pit.

100 metres straight down is the
detector,

which is operating at the moment,

so we're not allowed in
the building for safety reasons.

He is hoping to make one of the most
fearsome objects in the universe -

a black hole...

Si je produis des problemes pour
Atlas, je suis "eeeek"!

..a place where gravity is
so vastly strong that nothing -

not even light - can escape.

Problem is, if they open it,
that could set off the pit alarms.

It takes the entire mass
of an imploding star,

condensed into the space
of a small town,

to create the extreme
gravitational pull of a black hole.

They are normally vast,
and live at the centre of galaxies.

And yet Andy Parker is trying
conjure a micro black hole

right here at CERN,
using just a couple of protons.

It's perfectly possible that
in the high-energy end of our data

right now we are occasionally
making miniature black holes.

The protons are colliding below us,
they come together,

they have a lot of energy in them.
And gravity cares about energy.

It's the same as mass as far
as gravity is concerned.

So if you put a lot
of energy in a small space,

as we're doing right now,

then you could potentially form
a quantum-sized black hole.

A very, very tiny black hole.

It wouldn't be stable,
it wouldn't last a long time

and eat the planet, it would
disappear in a puff of radiation,

and we would see that puff
of radiation in our detector.

The only way it would be possible
to make these micro black holes,

at least 20,000 times
smaller than a proton,

is if, on the level of the really,
really small, we discover

that gravity is vastly stronger
than it seems in everyday life.

And that would change our view
of the familiar world,

and challenge something
we all take for granted -

that we live in a world
of three-dimensional space.

So this seems to be a perfectly
ordinary three-dimensional world.

There are three ways I can go.

I can go forwards and backwards,
side to side, up and down.

There can't be anything much more
than that, can there?

So if I want to go up the tower,
for example, over there,

I go sideways,
I go forwards and I go up.

Seems to be the only possibilities.

But not necessarily.

If we could conjure up
an extra dimension,

it could explain how you get super
gravity at the tiny scale.

Because, although gravity seems
strong in our everyday lives,

it's actually pretty feeble.

Gravity is a puzzle.

It's very, very much weaker
than the other forces -

actually a million, million, million
times weaker than the other forces.

It feels strong to us - right here,

I'm feeling uncomfortable about
gravity pulling me over the edge.

But that's because there's a whole
planet there pulling me downwards.

The other forces that are hard
at work holding the world together,

including the electromagnetic force,

are all vastly stronger
than gravity.

So here's a little magnet.

And this key, being held down

by all the atoms in the entire
planet pulling towards the centre.

And this feeble little
magnet can overcome

the gravity of the whole planet
quite easily.

Now, why is gravity so weak?

Well, one possible explanation
is that it's not actually weak.

It's just as strong
as the other forces,

but we're missing part of it,

and gravity is leaking
into the extra dimensions,

and so when we calculate
the strength of gravity,

we're only seeing
the piece that's in 3D.

Most of our gravity could be leaking
off into the fourth dimension.

All we get is the leftovers.

This would account
for the feebleness of gravity,

but where could this fourth
dimension be hiding?

Well, if there is an
extra dimension, it's everywhere.

The question is, why can't we see it?

All the others we can go off to
infinity along these directions

but maybe the reason we can't see
the fourth dimension is that

it's actually curled up.

If you went into it,
you'd go round in a little circle

and come back on yourself, just like
if you travelled on the surface

of the Earth far enough, you'd come
back to where you started.

But this would be on a very,
very small scale.

Hiding an extra dimension
may sound tricky,

but it's all a matter of scale.

It's a very strange concept,

but you can see it for people
who live in a flat world.

If we look down on the people
down below, then they're

moving around on a surface, which
is pretty much flat, and looked at

from this large distance up,
it just looks completely flat

and they move about, they cannot go
up and down because they can't fly.

From a great height, the tiny people
seem to live in two dimensions.

But if we zoom into the same
scale as the ant people,

you realise they can actually
move up and down as well.

Similarly, if we could get down
to a small enough scale,

we might find there is a fourth
dimension curled up.

It may sound an outlandish theory,

but if Andy spots his baby black
holes, all this would be true.

If we did see evidence of black
holes at the LHC, that would be

absolutely amazing because it
tells us that everything we think

we know about gravity, general
relativity and so on, isn't right.

Then you would have demonstrated
that the world is not

three-dimensional,
but four-dimensional or more.

And you would have made
a black hole in the lab.

So you get the Nobel Prize
for making a black hole in the lab,

you get the Nobel Prize for proving
general relativity wrong,

and you get the Nobel Prize

for demonstrating that the universe
is multi-dimensional.

I mean, how cool is that?

On our journey to find the smallest
thing in the universe,

things have indeed become
deeply strange.

We have dived down a rabbit hole
into a bizarre wonderland

where extra dimensions may lie
curled and hidden from our view.

But that's just
the beginning of the weirdness.

As we look even smaller,
beyond even the reach

of the Large Hadron Collider,
we have to rely on theory alone.

Professor Michael Green
is a founding father

of one of the strangest
theories in physics.

A theory that tells us that
the universe is made of strings.

String theory
starts off simply enough,

but it leads to some
mind-boggling conclusions.

The fundamental particles,
instead of being point-like objects

are now thought of
as being string-like objects.

Instead of the 17 particles
in the standard model,

everything is made
from a single object -

an incredibly tiny loop of string.

The characteristic feature
of a string, which makes it

different from a point
is that it can vibrate

and the different modes of vibration,
the different notes, if you like,

are seen as different
kinds of particles.

So there's this very appealing,

almost poetic way in which string
theory describes all the particles

in terms of different notes
on a string.

It's like the music
of the spheres almost.

It's a beautifully neat idea.

Each note from the vibrating string
produces a different particle.

There are, however,
one or two problems.

These strings are so small

that no-one has ever seen
anything remotely stringy.

Depending on one's viewpoint,
the size of these strings

can vary an awful lot,

from scales, which are sort of

a millionth of a millionth
of the size of a nucleus,

to scales, which are
much, much smaller than that.

If string theory
turned out to be true,

then a string would be the
smallest thing in the universe.

The trouble is, once we get this
small, the whole notion of small

and big may get turned
completely upside down.

Supposing these are quarks and
electrons, photons, the particles

that constitute the standard model.
Now we've got a problem because

if you believe that they're made
of something smaller, that's fine.

You'll find something
smaller inside.

But if you believe in a theory
like string theory,

then the notion of smallness
no longer means the same.

Ah, I haven't actually reached it.
It's even smaller than that.

And there's an even
smaller one than that.

I have a little speck here,
so that must be the smallest thing.

But then of course when
you're down to this scale,

you may have the whole universe
in your hand,

because the, the universe
itself started

from something this scale and
expanded into everything we know.

So this thing, which you think is
the smallest constituent,

may in fact be the thing that
contains all of us.

So the notion,
the difference between...

Oops, I hadn't even got there.

I dropped it,
I dropped the little universe.

The notion that this is the smallest
constituent is paradoxically

not at odds with the statement that
it may also be the whole universe.

String theory is underpinned
by some fiendishly complex maths.

But to make it work out,

the theory invokes not just
one new dimension,

but says that we live
in 11 dimensional hyperspace.

If you could describe exactly
how these extra dimensions

are curled up, you'd be able
to describe the exact nature

of everything in the universe.

The trouble is, there's more
than one way to curl them up.

So the equations of string theory

have very large numbers of solutions,
a humungously large number,

any one of which might
describe a possible universe

with its own laws of physics,

its own kinds of particles
and its own kinds of forces.

This whole body of solutions
of string theory has been called

the landscape string theory.

Each peak in the landscape
represents a different solution -

a different possible universe.

With each one just as
likely to exist as the next.

Most of these solutions
would describe universes

which are completely absurd.

The typical ones would be the ones,
which came into being and either

ceased to exist after a very, very
short time or exploded in such a way

that matter exploded apart and never
formed galaxies in the first place.

The fact that our universe
has existed for long enough

for galaxies to form and evolve and
planets to form and for life to form

and us to exist tells us that we are
living in a very untypical universe.

If they could find the right
solution - the right one

out of 1 followed by 500 zeros,

we'd have a neat explanation
for everything in our universe.

So the fascinating thing
is the multiverse idea

has been around for some time
in astrophysics,

but they didn't have a theoretical
way of understanding it.

And then along came string theory
and then the two got wedded.

Whichever way you look -
whether up to the largest scale

or down to the very smallest,
our universe may not be alone.

But for now, string theory
remains a theory,

with no experimental evidence

for any of its mind-boggling
predictions.

As we look down in scale,
things get increasingly cloudy.

To stand a chance of seeing strings,
we'd need a particle accelerator

a million, billion times
bigger than the LHC.

Is this, then, the end of the line
for the explorers

searching for the smallest
thing in the universe?

It turns out there could well be
a bottom of the rabbit hole -

an ultimate limit of
how small we can go.

And there may be a way to reach
this ultimate destination -

it's just a rather roundabout
route to get there.

Dr Giovanni Amelino-Camelia is
a theoretical physicist,

who 12 years ago came up
with an idea that could lead us

to the ultimate destination
at the bottom of the rabbit hole.

An idea that may lead us to question
the very fabric of the universe -

the three dimensions of space and
one of time, known as space-time.

Space time to an ordinary person
is space time.

What is space time?
There is no answer.

To us, space time is, er... Do you
understand what I'm trying to say?

The challenge is that
I don't have anything to work with

because the person who listen to me
thinks know space time very well,

but then if I asked what is
space time, he would have no answer.

Space time, they think
they know very well what it is.

"For God's sake, space time!
You know!"

But "you know" is all they can say.

So your audience is the worst,

because they think they know
a lot about this subject.

But then they know nothing,
completely nothing.

You see what I'm trying to say?
It's very tricky.

If we have any notion of space-time,
it is that it is smooth.

We can move smoothly from
one cafe to another,

can be reasonably sure how long
a journey will take.

But maybe not
if you get small enough.

The ultimate small destination
is known as the Planck length.

It is the theoretical limit of how
small anything can possibly be.

Some speculate that this could be
the ultimate level.

I mean, this could be where the laws
of nature are fundamentally written.

But to get to the Planck length,
you have to look a hundred,

million, billion times
smaller than a quark.

At this tiniest of scales,

we may find answers not just about
the smallest lump of stuff,

but about the very nature of space

and time in which
all the stuff sits.

What could be conceptually
more fascinating than

learning about the structure
of space time?

But our current theories with
all their limitations suggest

that at this Planck scale
that we're talking about,

we should expect space time to,
to be not smooth as we imagine

but more like, well,
more like the foam of a cappuccino

and actually perhaps in,
in a violently dynamical way.

The Planck length is where
the rules of the large

and the rules of the small
collide in a heady brew

called quantum gravity.

It's a seething tempest of space and
time known as space-time foam, where

the very fabric of space and time
twist and turn in every direction.

It is where the two great pillars
of modern physics,

general relativity
and quantum mechanics,

may finally be reconciled.

If we could understand
what is happening down here,

we could end up with
a theory of everything.

We are really far,
far away from, from this realm,

and yet some of the most
conceptually striking questions

about what, how is the universe made,

what are its basic rules, appear to
reside in this distant scale.

So it's... At one side,
we have this feeling of not having

any access to it, and yet
it appears to be the place where

most of the answers
we are seeking are somehow hidden.

All roads in physics lead to
the Planck length.

But until recently,

no-one had a clue how we would
ever know anything about it.

It was a problem Giovanni
was determined to solve,

seeking inspiration and reassurance
in the cafes of Rome.

I never understood what
triggers an idea.

And it's kind of reassuring to be
reminded that all this is

all about small - important,
conceptually important,

but small - I'm still here,
the Coliseum is still there.

When you're stuck chasing
a certain answer,

you often discover that all it took
to find the answer

was to look at the same problem
from a different angle.

MOBILE PHONE RINGS

From the office.

Pronto.

12 years ago,
Giovanni had a flash of inspiration

that we could reach the unreachable.

Over the last decade or so,
what we started to figure out is

that it is possible to get indirect
information on the Planck scale.

We cannot build a microscope
that show us, shows us

the structure of space time
at the Planck scale,

but we can get indirect evidence
about the Planck scale

structure of space time is made.

Any explorer will tell you that
if the way ahead is blocked,

you have to set off
in a new direction.

Instead of trying to look directly
down at the smallest scale,

the idea is to look up at the very
biggest scale possible -

the entire universe.

It's an idea that is now reality...

..and a trick that is now being
performed by the MAGIC telescope.

The idea is to use the vastness
of the universe

as a giant magnifying glass.

Dr Robert Wagner is using this
unique instrument to peer

at some of the most distant and
cataclysmic events in the universe.

Under good conditions,
as we have them right now,

we record 200 gamma ray
or cosmic ray showers per second.

The Earth is constantly being
bombard by high-energy cosmic rays,

gamma rays,
the most energetic form of light.

But Robert is looking for
the most extreme of these -

gamma ray bursts from colliding
neutron stars or exploding

black holes in distant galaxies.

Gamma ray bursts are very violent
events in the universe

and one key characteristic of them
is that we cannot predict them.

So they can take place at any
time at any place on the sky.

We get the information
from satellite experiments.

This information is transmitted
in an automatic way down here,

it takes about ten seconds,
and then the telescopes will fully

automatically go to those
gamma ray burst locations.

With these light weight telescopes

we're able to move to any point in
the sky within only 20 seconds.

Those bursts last anything between
one and 1,000 seconds.

Most of the bursts
are really short lived.

So it's of great essence to be
there as fast as possible.

Catching these violent
but fleeting events

takes many nights
of patient observing.

Well, this is a place I go right
after the observations,

and this of course gives
a quite different feeling

from looking at screens.

You look at the real sky
and actually the stuff

we are observing and hoping
to detect is somewhere up there.

Those black holes and galaxies,
they are so far very away,

but at the same time,
when you come here,

you realise they are real because,
you know, all the photons

which hit my eye right now
from those stars, they are real.

Although Robert spends
his nights looking out

into the far reaches of the cosmos,
he is actually trying to find out

how the universe works
on the very smallest scale.

Things up there are
so very, very far away.

The farthest galaxy we are looking
at is shining light at the time

when the universe
was just half its age,

it takes the light 7 billion years
to get to here.

So that's a distance
which, personally,

I cannot imagine, myself, right?
It's a very abstract number.

At the same time, the scales we are
looking at if we want to get to

the shortest scales are as similar
small as this distance is large.

So it's really hard to imagine
these things on scales,

which we see here on Earth.

But Robert's not really interested
in the explosions themselves.

They act as the biggest particle
accelerator in the universe,

way more powerful than anything
we could ever achieve here on Earth.

He is interested in
what happens to the particles,

in this case, photons,
while they travel towards us

on their 7-billion year journey

through what seems like
smooth, empty space.

But any distortions in the structure
of space-time at the Planck scale

would affect photons of different
energies in different ways.

Essentially, it's quite comparable
to cars driving on a road.

A big car will not feel
the fine structure of the road,

it will just roll along and will be,
you know, just as fast as normal.

Whereas a small car,
like a model car,

will feel every tiny ripple
in the structure of the street.

The large car would be
the low-energy photon,

because there is nearly no
interaction with the structure

or the ripples in the road.

Whereas the small car would be
the high-energy photon,

because it's smaller, there are more
interactions with the road,

and this makes
the photon travel slower.

The difference in speed is tiny.

But the length of the journey,
half way across the universe,

could magnify the effect into
something we might be able to see.

We just let those photons travel
along the universe,

and of course they travel
for billions of light years,

and only that long travel time makes
this tiny effect visible to us,

which is to say,
after such long travel,

we expect a few seconds' delay
of photons of different energies,

and of course this is a delay
which can easily be measured

with the MAGIC telescopes.

In 2005, just a few months
after switching on the telescopes,

a gamma ray outburst from an
active galactic nucleus tickled

the MAGIC mirrors, giving Robert
his first tantalising glimpse

down to the smallest place
in the universe.

It was the first time ever
we observed such an effect,

or, to put it in cautious words,
the hint of such an effect.

So clearly we were
absolutely stunned.

Soon, we realised there is something
in this data, which is extraordinary.

As soon as we dig deeper
and deeper in the data,

it became apparent that photons
of different energies may have

different arrival times
at the instrument.

Those photons had to travel
billions of light years.

The effect was on the order
of seconds, maybe five seconds.

The Planck length is so small

that after a race
of seven billion years,

the photons finished with
a gap of just five seconds.

There are two possibilities here.

The first is that the photons
rather inexplicably set off

five seconds apart.

The other explanation
is more revolutionary.

This five-second delay could be our
first glimpse of the smallest thing

in the universe, the first evidence
of a lumpiness in space-time.

If true, it would shatter one
of the most basic rules of physics.

To put it in simple terms,
the speed of light is not constant.

It is dependent
on the energy of the photon.

And that's revolutionary

because it's one of the
fundamental laws of physics.

Einstein predicted
speed of light is a constant,

no matter what you do,
no matter where you are.

Under no circumstances
should there be

a difference in the speed of light.

The conclusion from our measurements
that this is not the case

would mean quite
a revolution of physics.

The MAGIC observations provide
a tantalising glimpse

of what awaits us at
the smallest structures of space.

But to get there,

we've had to harness the entire
expanse of the universe.

The journey to the very small is
one of the most epic in science.

It takes us beyond
the limits of what we can see...

..inside fundamental particles,

which may not be
so fundamental after all...

..through a wonderland of extra
dimensions and multiple universes...

..down to the smallest
place in the universe,

a place that could
change the face of physics.

And surely we expect a revolution
in the laws of physics not

smaller than the one that took us
from Newton's laws

to quantum mechanics a century ago.

Subtitles by Red Bee Media Ltd