All language subtitles for Through The Wormhole S02E04 Are There More Than 3 Dimensions 720p.HDTV.x264-DiVERGE

There's never been
a stranger idea

in the entire history of science.

Down at the smallest scale.

Smaller than our cells.

Smaller than atoms, could the
world suddenly get bigger...

Branching out in new and totally
unexpected ways?

A quest to understand
the ultimate nature of reality

has gripped the greatest
living minds

and is forcing us to consider
a truly shocking possibility...

Are there more
than three dimensions?

Space, time, life itself.

The secrets of the cosmos
lie through the wormhole.

♪ Through the Wormhole 2x04 ♪
Are There More Than Three Dimensions?
Original Air Date on June 29, 2011

== sync, corrected by elderman ==

Up, down, backward, forward,
side to side.

If you want to get anywhere
on Earth,

these three dimensions
are the only ways you can go.

They describe any place
in our reality.

Or do they?

Many scientists now believe

our world is not
three-dimensional.

That somehow...
there are other ways to move.

Discovering
those hidden dimensions

is the biggest prize
in physics

and would forever change the way
we see the Universe.

When I was a boy down
in the Mississippi Delta,

bugs swarmed all summer long.

Some of them could
even walk on water.

But down below
there were creatures

who would occasionally dart up
and grab an unsuspecting bug.

The water bugs never seemed
to see it coming.

Why not?

Was it because, to them,
the pool had no depth,

no third dimension?

Could we be like water bugs,

unable to see the full extent
of reality?

Susan Barry knows all too well
the limits of human perception.

She was born with her eyes
severely crossed.

As a baby, her brain's attempts

to fuse the separate
two-dimensional images

from each eye into one 3-D image
ran into serious trouble.

Now, when I was little,
being cross-eyed,

if I, let's say, looked at
the apple with my right eye,

my left eye would be turned in
and looking at something else --

let's say, this clock.

So that would mean one eye
is seeing the clock

and one eye is seeing the apple,

and the brain might
interpret that

to think that the clock
and the apple

were in the same place in space.

Now, if you think about that,
that's an untenable situation.

Because how would you be able
to know how to move

and interact with things

if you don't know
where they are in space?

So, if your eyes are crossed
like that,

you have to find a way to adapt,

and one way to adapt,
the way that I used,

was I simply threw out
the information from one eye,

the eye that was turned.

Freeman: Susan had eye surgeries
when she was a child,

but they only changed
her outward appearance.

She could only see
two dimensions.

Nothing had any depth.

Everything,
even her own reflection,

looked entirely flat.

And it seemed she would live
that way forever.

For the past half century,
there has been a belief

that if you did not develop
the ability to see in 3-D

within the first years of life
in early childhood,

you could not develop it
as an adult.

Freeman: But in her late 40s,

Susan began a rigorous
vision retraining program

to try to teach her eyes to lock
onto the same target

and give her brain the chance
to discover

an extra dimension of space.

One day,
after her 48th birthday,

something incredible happened.

Barry: I went out to my car and
I sat down in the driver's seat,

and I went to look
at the steering wheel,

and it had popped out.

It was popped out in space with
this palpable pocket of space

between the steering wheel
and the dashboard.

And I had never seen anything
like that.

And all that day, my stereo
vision would emerge

like intermittently,
unexpectedly,

and it would be amazing.

The sink faucets were really
jutting out toward me,

and I can remember just admiring
the sink faucets

and thinking that I had
never seen an arc

as beautiful as the arc
of those sink faucets.

Freeman: The sudden appearance
of this extra dimension

was a revelation to Susan Barry.

But the idea
that another dimension

beyond the three we know

might be hiding from all of us
is now at the center

of the world's most important
scientific investigations.

Harvard Professor of physics
Lisa Randall

is at the forefront
of this hunt.

She sees the world differently
from you and me.

Randall: It was just one day
I was walking to work,

and I realized I really did
think that extra dimensions

could be out there.

Freeman: The main reason
for her conviction

that there must be more
than three dimensions?

This paperclip.

It's really strange.

If I take this tiny magnet,
I can pick up this paperclip

even though the entire Earth is
pulling down on this paperclip.

If you think about it,
the force of magnetism

that is exerted on this
paperclip is enough to compete

and actually overwhelm the force
of gravity that's acting on it.

So there's a mystery there,

because why is electromagnetism
so much stronger

than the force of gravity?

Freeman:
Physicists have discovered

that we live in a world governed
by four primal forces.

There is electromagnetism,

the force that affects objects
with electric charge...

The strong nuclear force,

whose power is unleashed
in nuclear weapons,

and the weak nuclear force
that triggers radioactive decay.

These first three forces are
all roughly equal in strength.

But the fourth force, gravity,
is much weaker.

In fact, it's around a trillion,
trillion, trillion times

weaker than the other three.

So we're trying to understand
what can explain why gravity

is so much weaker than
the other elementary forces.

And one of the possibilities
that we start to think about

quite seriously
in the last decade or two

is that there could actually be
additional dimensions of space.

If that's true, it could be
that gravity's weak

because
it's actually concentrated

somewhere else
in another dimension.

Freeman: The idea
that extra dimensions

might be a hidden part of
our reality is as old as Plato.

He imagined the world we live in

to be like the wall of a cave
lit by firelight.

Shadows dance across
our two-dimensional world

cast by objects in the body
of the cave

in a third dimension
that's hidden from us.

A three-dimensional geometrical
shape like the tetrahedron,

which has four equal sides,

could cast a distorted shadow
on the wall

so that one side looks much
shorter than the others.

Just as an extra dimension

can hide the true length
of one of the sides,

so, too, it might be hiding
the true strength of gravity.

And Lisa Randall's efforts
to learn about extra dimensions

begins, like Plato's,
with studying shadows.

So here I have
a three-dimensional cube.

Now, if I had
a single projection,

I might actually confuse that,

for example,
of just being a square,

which is two-dimensional.

However, by rotating the object

and looking
from different angles

with different projections,

you can tell that what you have
is a three-dimensional object.

By putting together
the information,

you can deduce what's there.

Freeman: Just as
a two-dimensional shadow

can help us learn the true shape
of a three-dimensional cube,

we can explore
a four-dimensional cube,

a hypercube, by looking at its
three-dimensional shadows.

We can look at different
projections of a hypercube.

What we would see

are things from one angle
that might look a cube.

From other angles, it might look
like a cube inside a cube.

It might look like
it's turning itself inside out

because we're not really
in the fourth dimension,

so it does things
that we're not familiar with

because it has this whole
other dimension of space

that it can play with.

Freeman: But if a fourth
dimension does exist,

shouldn't we see objects
changing shapes like this,

even turning themselves
inside out?

Could it be that whatever exists
in the fourth dimension

is somehow blocked
from entering our world?

Or could they be hidden
some other way?

Randall: So,
if there are extra dimensions,

they have to be
pretty well-hidden

for us not to have seen them.

So, why would that be?

It could be
these other dimensions

are just so tiny
we just don't notice them.

Freeman: But this scientist

thinks he's discovered a new way
to detect them

and that dimensions we can't see

control the way everything
in the Universe moves.

What would it look like

if we were to travel into
a fourth dimension of space?

It's not easy to imagine.

But here's one way
to get an idea.

Think of the palm of my hand as
a world of only two dimensions.

If a three-dimensional ball
were to pass through it,

what would the inhabitants
of my palm see?

A circle that grew

and then shrunk down to a dot
before disappearing.

So, if I could move
into the fourth dimension,

my three-dimensional projection
would distort, shrink,

and finally flicker out of this
world, becoming totally dark.

U.C. Irvine Physicist Tim Tait

thinks most of the matter
in the Universe

may have moved into the fourth
dimension and gone dark.

He, too, spends most of his time

trying to escape the dimensions
that normally confine us.

Tait: When you scuba dive,

you become immediately aware
of the fact

that you have to control
how high you are,

how deep, you know,
you are in the water,

how close you are
to the surface,

and so you instantly
become aware of the fact

that there's another dimension

in a way that you can't really
feel when you're on the ground.

Freeman: Tim believes
that yet another dimension,

a fourth dimension,
might be the key

to explaining one of the deepest
mysteries of the Universe --

the mystery of dark matter.

In the recent years, we've
become really aware of the fact

that when we account for all
the stuff in our Universe,

there's stuff that's missing.

We can see it pulling on other
things gravitationally,

but other than that, it doesn't
leave any trace that it's there.

Freeman: Scientists are
convinced dark matter exists

because it's affecting the way
stars rotate around galaxies.

The gravitational pull of it
is so strong,

that they estimate dark matter

outweighs normal matter
by five to one.

We really don't know
what dark matter is,

but there have been many ideas
that have been proposed

to try to explain it,

and my own personal take
on dark matter

is a theory
with extra dimensions.

Freeman: Tim's idea is that
dark matter could be evidence

that a fourth dimension exists,

a dimension that is almost
impossible for us to see.

Tait: So an analogy
for the extra dimension

would be looking at the anchor
line of a boat.

When you look at the line
from far away, you see a line.

You see a long, thin object,

and you don't realize
that it actually has width,

that it has an extra direction
that you can move

if you were sitting
on the surface of it.

Close up,
it's actually a cylinder.

It's big and fat, and you can
move around the periphery of it.

Freeman: If particles are moving
around this cylinder,

and if it were small enough,

they would look to us like
they were not moving at all.

So this is our model
for an extra dimension.

We have the Bob,
which represents a particle.

As I spin the particle around,

as it goes in a circle with
the string holding it in place,

and that represents it moving
in the extra dimension.

So, let's see how that works.

So here we have it spinning
around in the extra dimension.

As it gets closer and closer,
it speeds up.

It moves faster and faster
and has more energy.

Even though this particle
looks like it's standing still,

it could actually be moving
very, very fast

just in a very, very
small circle.

Freeman: Any particle that
is moving must have energy,

and according to the most famous
equation in all physics,

if you have energy,
you have mass.

That gave Tim a flash
of inspiration

about what dark-matter particles
might actually be

and how they might lead us

to discovering
the fourth dimension.

Tait: So photons
are particles of light,

but if there's another direction
that photons can travel in,

we can actually get
a dark-matter particle

by just taking
these massless photons

and letting them move around in
a circle in the extra dimension.

Freeman: If Tim's right,

dark matter is actually made
of light,

massless particles
that appear to have mass

because they are racing around

a tiny fourth-dimensional loop
that's too small for us to see.

But how and when

did these photons leave
our three-dimensional world

and enter the fourth dimension?

One way you can try
to understand this

is if you think about
a round-about in a playground.

It's spinning around
really fast.

Actually get
onto the round-about,

a child is gonna have to run
around it at the same speed

that it's spinning.

But if it's spinning faster
than the child can actually run,

then there's no way
to get onto it safely.

Most particles we have today

just don't have
that much energy.

But when the Universe
was very young,

it was very small
and it was very hot.

And at that time,
particles had a lot more energy,

and they were able to actually
get into the extra dimension.

Freeman:
Right after the Big Bang,

super high-energy particles
of light

may have blasted their way
into the fourth dimension.

They have been stuck there
ever since

and appear to us today
as dark matter.

But Tim thinks there might be
a way for them to get out,

and when they do,
they could bring us proof

that the fourth dimension
really exists.

If two photons are moving around
this curled-up dimension

in opposite directions,

they might occasionally
bump into one another.

When they collide,
they annihilate and burst out

as an intense shower of energy
into our 3-D Universe.

Even though this event is rare,

these collisions
in the fourth dimension

should create a telltale signal.

Man: Engines start. Liftoff.

Freeman: In 2008, NASA launched
the Fermi Space Telescope,

a probe designed to pick up the
intense radiation, gamma rays,

created by cosmic cataclysms
like exploding stars.

But it should also detect gamma
rays from dark-matter photons

as they annihilate one another.

So, as it collects data, we
understand the gamma-ray sky,

and we start to look for where
the dark matter might be.

Freeman: Fermi has already
discovered a sea of gamma rays

emanating from the center
of our galaxy.

But much more work is needed

to prove this signal is coming
from the fourth dimension.

Tait: So obviously, I hope that
tomorrow we declare victory

and explore the extra dimension.

On the other hand,

I don't know exactly when
we're gonna discover it.

I think, though, the prospects
today are much better

than they have been in the past.

Freeman: The Fermi Telescope
will continue gathering evidence

from the depths of space
until around 2015.

But proof that there are more
than three dimensions

may not come from so far away.

Right now the biggest experiment
mankind has ever built

is trying to find them
under the Swiss Alps.

The goal of science

is to reveal to us the deepest
workings of nature.

And nothing in science attempts
to go deeper than string theory.

String theory says that every
single particle of matter

and energy in the Universe

is actually a tiny,
vibrating string...

A string that vibrates not in
three dimensions, but in nine.

If string theory is right,
at every point in space,

there are six extra dimensions
curled up incredibly tight.

These hidden dimensions

could solve all the mysteries
of physics.

But there's a problem.

Since string theory was first
proposed over 40 years ago,

there's not a single shred
of evidence to support it.

Thousands of scientists are
on the hunt for that evidence.

Under the foothills of the Alps
in Geneva

lies the Large Hadron Collider,
the LHC.

It's a 17-mile-long
circular racetrack

designed to smash
subatomic particles together

at phenomenal energies.

Caltech Physics Professor
Maria Spiropulu

has been working
at the atom smashers in Geneva

since she was an undergraduate.

She has seen trillions
of particles fly

like subatomic shrapnel
through the detectors.

The LHC, I think,
is the most ambitious

and technologically complex
scientific project

that humanity
has ever attempted.

We got a billion collisions
per second,

and this is a daunting task
to record this data.

Freeman: Maria and her
colleagues have sifted through

this immense pile of data

and identified dozens
of tiny subatomic particles,

the basic building blocks
of matter.

But they've never seen
the strings

that lie at the heart
of each of these particles.

String theory predicts
that they must be

a trillion, trillion times
smaller than an atom.

Put that another way --

if an atom were the size
of the solar system,

a string would be the size
of a light bulb.

And the smaller an object is,

the more energy it takes
to see it.

The energy of the subatomic
particles racing around the LHC

is staggeringly large.

Protons zip around this ring
so fast that a beam of light

only outruns them by about
eight miles an hour.

But to see fundamental strings

and their six
curled-up dimensions

requires levels of energy
almost beyond comprehension.

Spiropulu:
If you want to make a collider

that will actually produce
something like strings,

it would take an accelerator
much bigger than the LHC,

much bigger than the Earth,
the circumference of the Earth,

possibly much bigger
than the Milky Way.

Freeman: But there may be a way
to prove that string theory

and the six extra dimensions
of space that come with it

is correct,

a way that does not require
seeing tiny strings directly.

Joe Polchinski
is one of the world's

leading string theorists.

Like many physicists,

he draws inspiration
from being close to nature.

It's great to get out here
in nature in the mountains

to think about things a bit.

When you get to the top
of a climb,

you really get
a much bigger picture.

Freeman: Joe has probably

delved deeper into the workings
of string theory

than anyone else,
and in doing so, he realized

something crucial was missing
from the math.

So, we know that the basic
building blocks of nature

have to be really small,

smaller than anything
we've ever seen --

probably a whole lot smaller.

So, if these building blocks
are strings, you know,

they're very elusive.

How do we know
that they're there?

And so it's challenging.

And there was this one
calculation we would do,

and the answer that the math
was giving us

wouldn't match up
with the physical picture

we thought we had.

It turned out
that the problem was

the strings themselves
were not enough.

What the math was telling us was
there was another kind of thing,

another sort of object
in the picture.

Freeman: In 1995,
after many years of work,

Joe made his way through
the torturous math

and discovered the source
of strings.

He called these objects
D-branes.

So we're out here on this nice
hike out here in nature,

and we've got
this beautiful spider web,

which is a nice model
for some of these ideas.

So D-branes are these
higher-dimensional objects.

They can be two-dimensional,
three-dimensional, or even more.

And this spider web is
two-dimensional, a sheet,

and like a sheet,
it can flex and bend

the way D-branes
can flex and bend.

Now, it's not a perfect model

because this web is stuck
between these two branches,

but the D-branes
can go on forever.

They could be of cosmic size,

stretching from one side
of the Universe to another.

And if you look close,

you see that there are these
little bugs stuck to it

the way strings get stuck
to a D-brane.

Freeman: In Joe's theory,
D-branes could take on

any of the nine dimensions

that exist in the mathematics
of string theory.

Our entire Universe could be
a three-dimensional brane,

a block of space to which
all the strings,

all the matter in our Universe
is stuck.

Now you have the branes
doing what they do,

and you find that very possibly

the dimensions could be much
larger than we thought about,

large enough to see
particle accelerators,

large enough to maybe
have effects on what we see

in astrophysics, in some of
the physics we see from space.

Freeman:
Thanks to Joe's discovery,

scientists around the world
are fueled with fresh hope

that they may soon detect
extra dimensions.

If you, me, every star,
every galaxy in the cosmos

is stuck
on a three-dimensional brane,

then a fourth dimension

wouldn't have to be
a tiny fraction of an atom.

It could be much bigger.

The discovery
of extra dimensions

would be one
of the biggest breakthroughs

in the history of science.

But it might also
spell disaster.

Because the experiment
that proves they exist

might also create a black hole
here on Earth.

In 1609, Galileo peered
through his telescope

and spied the moons of Jupiter.

His discovery of those
four tiny points of light,

invisible to the naked eye,

changed our understanding
of our world.

Extra dimensions of space

will be much harder to see
than Galileo's moons,

but if we discover them, it will
change our understanding

of the entire Universe.

This piece of delicately
balanced equipment

could be the device that
discovers the fourth dimension.

It sits in a basement
at the University of Washington

and belongs to this man.

Eric Adelberger,
along with a small team,

has spent the last decade

watching this torsion balance
twist back and forth,

hoping it reveals evidence

that there are more
than three dimensions.

Gravity is really
an amazing story.

It was the first
of the fundamental forces

that the physicists
learned about.

Isaac Newton had his theory
of gravity,

which has been tested very well
in the solar system.

But it's not really been tested
very well at all

at very short distances.

And the short distances

are now where all
the theoretical action is,

so to speak.

Freeman: The forces
Eric needs to measure

are incredibly weak.

Even though the lab
is underground,

his data is frequently marred
by trains, rush-hour traffic,

even airplanes
flying miles overhead.

The forces we're measuring are
really extraordinarily tiny.

To get some idea,
if you could cut a postage stamp

into a trillion little pieces
somehow

and could weigh one of those
little pieces somehow,

that's the kind of forces
that we're measuring.

Freeman: If the force of gravity
deviates from Newton's laws

at very small distances,
it would be a telltale sign

that an extra
microscopic dimension exists.

It's a principle Eric
knows firsthand

from his passion outside the lab

tending another set
of delicate objects.

A nice way to understand this
is this analogy

between the way gravity
spreads out

in varying number of dimensions

and the way flow of water
spreads out

in varying number of dimensions.

We got a steady stream of water

that flows out of these two
outlets at the top,

and it falls into a channel and
is confined in one dimension.

And it runs down
along the one dimension,

and we've made one channel twice
as long as the other channel.

And we're gonna see --
measure the flow of water

by watching how much the level
of the water in this bucket

changes compared to this bucket,
where the water's had to travel

twice as far
in that one dimension.

The amount of water

that's flowed through the longer
one-dimensional channel

is just the same
as the amount of water

that's flowed through the
shorter one-dimensional channel.

So what this tells us
about gravity is that if gravity

were operating
in a one-dimensional world,

it would be the same
if objects are close together

or if they're very far apart.

So now we're gonna see
what happens

when the water flows
in two dimensions.

In our two-dimensional
experiment,

the beaker that was closer
to the water source

got twice as much water

as the beaker that was farther
from the source.

If these two beakers here
were our measure of gravity,

we would know that we were
in a two-dimensional world

because we got twice as much
water over here.

Okay, now we're gonna see
what happens

when the water spreads
in three dimensions.

Freeman: When water spreads out
in a three-dimensional world,

when you place the bucket
twice as close to the source,

you get four times
as much water.

So if we lined up the beakers
from the three experiments,

we'd see that the 1-D beakers,
the water was the same height,

2-D, the near beaker
had twice the water,

and in the case of 3-D,
it had four times the water.

Now, if we could imagine that we
were living in four dimensions,

what would we see,
we would expect to see

that the nearer beaker had eight
times the amount of water

that the more distant one had.

Freeman:
The more dimensions there are,

the faster the force of gravity
changes with distance.

Well, we've measured gravity
down to roughly 50 microns.

That's about half the diameter
of a hair on your head, okay?

So far, Mr. Isaac Newton
is still correct.

Freeman:
If Eric can get even closer,

the hidden world
of extra dimensions

could suddenly pop into view.

Adelberger:
There are reasons to think

that, you know, the region
between 50 and 10

might contain some real
surprises, and, of course,

that's stimulating
our enthusiasm

for doing the experiments.

Freeman: On the other side
of the planet,

at the Large Hadron Collider,

Particle Physicist
Maria Spiropulu is also looking

for unexpected changes
in the force of gravity.

But if her experiment
is successful,

she'll create something never
before seen on Earth --

a black hole.

Spiropulu: It is quite possible
the LHC experiment

can produce the so-called
microscopic black holes.

Freeman: This is not the type
of black hole

that is borne
from a collapsing star,

where the core gets so compacted

that nothing can escape
its gravitational pull.

What Maria is looking for

is evidence
of a microscopic black hole.

If the LHC can force
two particles

sufficiently close together,

and the extra dimensions
are large enough,

gravity could start growing
much stronger than expected,

eventually compacting
the two particles enough

to form a tiny
subatomic black hole.

But don't worry about moving
to Mars just yet.

The black holes Maria and her
colleagues expect to create

are tiny...

So tiny that they will evaporate
in a fraction of a second.

The microscopic black holes,
as soon as they are produced,

they immediately decay with
a very, very short life-span.

There is a spray of these
particles, and that is the clue

that such an object
might have been created.

Freeman: The LHC has been
looking for these black holes

for over a year.

So far they found no hint

of even a single black hole
being created.

Extra dimensions remain elusive.

But Lisa Randall thinks
that might be

because they're different from
what most scientists expect.

She believes extra dimensions
are warped

and that they are passageways
to a parallel Universe.

Extra dimensions
are not easy to see.

If they were, we'd have
found them long ago.

Many scientists now believe

we'll never have the technology
to find them.

But extra dimensions might still
reveal themselves...

because they might be separating
us from a parallel Universe.

An entire cosmos
could be lurking

less than...a trillionth
of an inch away.

Harvard Professor Lisa Randall

has a radical new idea
about extra dimensions,

one that will change the way
we see our entire Universe.

She began with string theory,

the idea that all
the fundamental particles

are just vibrations of tiny
nine-dimensional strings.

Then she added in
Joe Polchinski's ideas

that strings making up
all the stuff in our Universe

had to be stuck to a giant
three-dimensional object

called a brane.

There are two types
of strings --

strings with ends

and strings that are closed
loops, like rubber bands.

And the strings with ends, those
ends have to be somewhere.

They can't just be anywhere
in higher-dimensional space.

They have to be on the surface
of a brane.

And if that's true,

the particles associated
with that string

will also be on the brane.

And it turns out that all
the matter we know about,

and also the forces
through which they interact,

might all be stuck on a brane
through this mechanism,

except for gravity.

Because gravity is never
associated with open string.

Gravity's associated
with a closed string.

And closed strings have no ends.

There's no mechanism that
makes it stick to a brane.

A closed string can be anywhere.

Freeman: Lisa's math suggested
that gravity might be so weak

because the closed-loop strings

that carry this force,
gravitons,

are being pulled away
from our brane

and concentrated instead
in a parallel Universe

that's separated from us
by a fourth dimension.

Randall: You can imagine that
these two buildings behind me

represent two different branes,

and we maybe are living only
in that building or that brane.

If gravity is concentrated
at the other building,

we might only get a tail end
of gravity.

It might be that
that could explain

why gravity is so weak for us.

Freeman: Gravitons flow freely
between our brane

and the one that's across
the fourth dimension.

But the gravity in that parallel
world is so strong,

it compresses space

trillions upon trillions
of times smaller than ours.

The space between these
two brane worlds is warped.

As gravitons move

from the dense-gravity brane
to our brane,

they spread out, and their force
gets far weaker.

Things get rescaled

as you go from one place in
an extra dimension to the other.

So whereas things might be
extremely heavy here,

they could be
exponentially lighter here,

which would naturally explain
why gravity is so weak.

Freeman: Lisa Randall's idea
of a warped fourth dimension

separating us
from a parallel Universe,

where gravity is just as strong
as the other forces of nature,

has set the world of physics
alight.

Back at the Large Hadron
Collider in Geneva,

the beams will soon be
smashing together

with enough force
to produce particles

that could prove this warped
dimension really exists.

Randall:
Well, if this idea is right,

you would actually be able
to make particles

that essentially have momentum
in another dimension.

Now, we don't see
that other dimension.

What we see is the effect
as if the particle had mass,

and the mass turns out to be
the right mass

that it can be produced
at the energies

of the Large Hadron Collider,
we hope.

Freeman: Any day now, news
may come from the Swiss Alps

that the world
is fundamentally different

from the way
we've always imagined it.

But there is one more twist
to this epic hunt

for warped or curled-up
extra dimensions.

One scientist thinks our search
is doomed to failure.

She does not believe there
are more than three dimensions.

She thinks there's only one.

How do you build a Universe?

Do you need three dimensions?

Or do you need four?
Nine? Or more?

These are the most
fundamental questions

scientists can ask
about our reality.

But the simplest questions are
often the hardest to answer.

Swarms of scientists
at the Large Hadron Collider

and labs around the world

are hunting for evidence
of extra dimensions,

be they warped or curled up
in tiny loops.

They hope to make
a major breakthrough

within the next few years.

But Renate Loll, a physicist
at the University of Utrecht,

isn't holding her breath.

Of course, one of the problems
you have in string theory

is that there's all
these many dimensions.

Then you have to explain
why you only see a few of them.

That would be wonderful
if you could do that.

But currently
that's too difficult

or no one has managed
to show that.

Freeman: Renate believes

that the extra dimensions
predicted by string theory

are merely a mathematical quirk

and the theory itself
is likely to be wrong.

Of course, it raises
the question of,

"Well, can we maybe do

without these extra dimensions
whatsoever?"

Freeman: Renate Loll's dislike

for the extra dimensions
of string theory

is matched only by her passion

to attack the same puzzle
it was created to solve --

the mystery of gravity.

Einstein realized
that gravity could be seen

as simply a bending of space
by massive objects.

His theory of general relativity

was a masterpiece
of modern physics.

But it left a serious problem
unsolved --

how does gravity affect space
on the microscopic level?

So if you ask questions

that have to do, say,
with the very, very small

and that involves anything
that has to do with gravity --

so, how do objects interact
gravitationally

on very, very short scales --

then you need an extension
of Einstein's theory

because it doesn't cover
that range.

Freeman: Renate has taken on
that challenge.

She's trying to develop new laws
of gravity

that apply even
at the smallest distances,

and she's testing them
in computer simulations.

She begins with a collection
of microscopic points of space

and attempts to stick them
together with gravity.

In other words,
she is growing space.

The last time this happened
outside a computer

was about
13.7 billion years ago.

It was part of an event
you've probably heard of --

the Big Bang.

Renate is working
on a much smaller scale,

but the microscopic Universes
she is cultivating

have some
very unexpected properties.

Imagine you're given a space
or just a piece of space

and you want to learn about what
it is, and, in particular,

you may want to learn about
what its dimension is.

So one experiment
that you can actually do

to find out
what the dimension is,

is to let an ink drop fall in it
and then see what happens,

see how the ink spreads
in the space.

Freeman: In water, ink spreads
into three dimensions.

On a piece of blotting paper,
it spreads into two.

But when Renate tested
how things spread out

inside her computer-simulated
Universes,

the results looked something
like this.

Loll: Watch what happens now.

It filled out much less ones
than we expected

on small scales,

and that's a true indication

that the dimension's
actually smaller

than what we expected.

It's smaller than three.

Freeman: Renate's simulations

looked like
they had three dimensions,

but at root, they only had one.

If her theories
of gravity are right,

it suggests that solid space
is not solid at all.

Down at the smallest scales,

it might be built from a mesh
of one-dimensional lines.

Is this the fundamental truth
about how space is formed?

Is one dimension
all there really is?

So the order is, one would think
of the dimension of a space

as fixed, just God-given.

It's just there.

But what happens
on very, very small scales?

And there's the story we find
is totally different.

The space appears to have
a smaller and smaller dimension

as you explore it
on smaller and smaller scales.

Freeman: Other scientists
are not convinced

Renate's one-dimensional
Universe is correct.

Their bets are hedged
on a Universe

with many extra dimensions.

The truth is still elusive.

But it's not out of reach.

Randall: It's a problem
we really want to solve.

We really think there has to be
an answer --

really tells us that something
has to be there,

and it could tell us

that there's some really exotic,
underlying matter

or physics or forces that
we haven't thought about yet.

In the end, there is,
you know, some theory.

There's some simple, elegant
theory out there

that accounts for all of nature,
for everything we see,

and we feel like we could be
very, very close to it.

So when you have
shocking questions,

it takes sometimes shocking
ideas and answers

to try to put your arms
around this.

Are there nine dimensions
or only one?

Is this hidden space warped
or curled up in tiny loops?

We don't know yet.

But we can be evermore sure
of one thing.

The three-dimensional world
we thought we lived in

is only what we see.

Reality is almost certainly
a lot stranger.

== sync, corrected by elderman ==