All language subtitles for Through.the.Wormhole.S02E02.720p.HDTV.x264-DIVERGE.HI

Space.

It seems like
it must go on forever.

But does it?

Out there in the farthest depths
of the Universe,

might there be someplace

where something turns
into absolutely nothing?

Scientists are probing the
far-flung reaches of the cosmos,

trying to detect
that outer limit,

to find the shape of space.

Now surprising evidence suggests

that not only is there a place
where the Universe ends,

but that there might be
something lurking beyond it --

something unimaginably alien.

Space, time, life itself.

The secrets of the cosmos
lie through the wormhole.

♪ Through the Wormhole 02x02 ♪
Is There an Edge to the Universe?
Original Air Date on June 15, 2011

== sync, corrected by elderman ==

Once in a while,
a really big idea comes along --

one that completely changes
our concept of who we are.

In 1543, Nicolas Copernicus
proved that the Earth

was not at the center
of the cosmos.

In the 1920s, Edwin Hubble saw

that all the galaxies
in the Universe

were rushing away
from one another,

sparking the idea

that the Universe
had not been here forever

but was created
in one explosive moment --

the Big Bang.

Now another monumental change
is upon us.

We've long imagined the Universe
to be infinite in size,

but many cosmologists now think
the Universe...

is finite.

Some believe
they even know its shape.

If we do discover
an edge to the Universe,

we'll have to grapple

with another very challenging
and unsettling question.

What lies beyond the edge?

Every day
on my way home from school,

I used to pass a long wall.

It was at least twice my height.

I had no change
of seeing over it,

but I could hear strange sounds
coming from behind it.

My mind ran wild

imagining what might be
back there.

Wild animals?
Outlaws?

Or some fearsome monster?

I would press my ear
up against it

to try and decipher
what it could be.

I never did find out,
but I never stopped wondering.

Neil Cornish is a cosmologist

who lives and works in
the big sky country of Montana.

The only walls out here

are fences to keep his horses
from roaming off.

Neil is the latest
in a long line of thinkers

to contemplate
the size of the Universe.

The first we know of was
a Greek philosopher king

called Architus.

The Greek philosopher Architus

offered an argument for why
the Universe must be infinite.

He said, "if I was to go out
to the edge of the Universe

"and then extend my staff
to here,

"that would now be
the edge of the Universe.

"And then, if I was
to extend my staff to here,

"that would now be
the new edge of the Universe.

"And if I was to extend
my staff out to here,

"that would now be
the edge of the Universe.

So the Universe
must be infinite."

Freeman: Architus's mental game
set the tone

for over 2,000 years
of scientific dogma --

our Universe
must be infinitely large

and has existed forever.

But that dogma
is now being challenged.

So, one problem
with an infinite universe

that's not just infinite
in space

but also infinite in time --
has no beginning --

you have an infinite number
of stars.

So the sky would be just
completely covered in white,

bright, bright --
so bright that it would fry you.

So, when we look out at night,
that's not what we see.

We see a star here or there

and then, essentially,
darkness all around.

So this tells us something.

It tells us we don't live
in an infinite Universe

that's infinitely old.

Freeman:
It was our dark sky

that inspired a revolutionary
idea about the cosmos --

that it cannot
have been here forever.

The Big Bang --

a moment where all the space
and matter we can see

burst into existence,

expanding out
from a single point.

But the Big Bang
creates a problem

for astronomers searching
for the edge of the Universe.

Because it takes light time

to travel across
the vastness of space,

astronomers were always
looking back in time,

and, eventually,
they run out of time.

Cornish: So, when we look
out at the stars at night,

we're seeing those stars
as they were years ago.

The nearby stars,
maybe a few years ago.

Looking out across the galaxy,
thousands of years ago.

And going back and back,

we see galaxies back
billions of years ago.

And then, beyond that,
where we see no more galaxies.

13 billion years ago

is the next thing
that we've managed to image,

and it is the after-glow
of the Big Bang.

Freeman: It's called
the cosmic microwave background,

and it's a picture of the way
the Universe looked

about 400,000 years
after the Big Bang.

Cornish: The Universe is filled with
this hot gas, this hot plasma.

Light really can't go anywhere.

So we can't see
any further back,

just as we can't see
into the Sun.

Freeman:
The cosmic microwave background

is a barrier
that blocks our vision.

Behind it,
there could be an edge.

Or perhaps the Universe
does extend on forever.

But no matter how powerful
our telescopes become,

that domain
will never be visible.

But there might be
another way to discover

if the Universe has an edge.

Janna Levin is a theoretician

who uses complex
numerical simulations

to solve some of science's
most challenging problems.

[ Groans ]

It might surprise you that
a game as old as "Asteroids"

can teach us something
about the Universe,

but there's a rule in the game

to make a world out of the game
that makes sense,

where, if you exit the top,
you re-enter the bottom,

or if you exit the left,
you re-enter from the right.

And that rule makes this world

in which you're
playing the game,

this space in which
you're playing the game,

a finite space.

And that's kind of like

the rules we're imagining
for the Universe.

Freeman:
If our Universe is finite,

scientists believe its edges
must also be linked,

that the entire cosmos

must act like
a giant game of "Asteroids."

If we could bend this space,

we would see that it looks
like something more intuitive.

Like, for example,
if I were to take this menu

and apply that rule
from the "Asteroid" game.

You know, I exit the top,
I enter the bottom.

That's exactly the same
as taking the menu

and rolling it up
and gluing the sides together.

It gives the same effect.

And if I could bend
this rather too stiff menu,

I would try to bend it

so that the two edges
came together and were glued.

And then I'd be making
something kind of like,

you know, a bagel --
a classic, New York bagel.

And the bagel is glued together
not just like a cylinder

but also around the other side.

Freeman: Even though the surface
of this bagel is clearly finite,

no one living in this space
would ever run into an edge,

so it feels boundless
and infinite.

When we live
inside the Universe,

we can't step outside of it.

There's no other dimension
to look down from,

onto our 3-dimensional Universe,
so it's harder to visualize.

But we can use the rules

like the rules that are used
in the "Asteroids" game.

And then we add one more rule

for three rules
for three dimensions.

Go out the back face,
come in the front.

Freeman: If we do live
in a cosmic asteroid cube,

there is a way
we could discover the edges --

not by flying a spaceship
across them,

but by standing still

and watching light
as it wraps around the Universe.

If the Universe
were the size of a room

and you stood in the middle
of it holding up a lantern,

light beaming out from your back

would zip out one wall

and re-enter the room
from the other side

so you'd see an image
of your back

on the wall in front of you.

Looking out to the right,

you'd see light coming
from your left side.

The room would appear
to be covered in mirrors.

Whichever wall you looked at,
you'd see an image of yourself.

When we look at the night sky,

we don't see
this hall of mirrors.

But space is so vast,

light could take
billions of years

to loop around the Universe.

Space and time
on this epic scale

mean that mirror images would
look nothing like one another.

So, imagine this corral
is our Universe.

There will be repeats
of this corral ad infinitum,

giving an illusion that we live
in an infinite space.

But if this corral
were just 30 light-years across,

when I look out there,

I wouldn't see myself
as I am now.

I'd see myself
as a 10-year-old boy

'cause I'd be looking
30 years back in time.

Freeman: Our Milky Way is around
13 billion years old.

It's been around almost as long
as the Universe itself.

Could a distant image
of the Milky Way

be hidden somewhere
in the night sky,

disguised the way it looked
5 or 10 billion years ago?

If it is, how would we even
recognize this youthful twin?

This scientist believes
the cosmos is a hall of mirrors,

that the Universe is finite,

and that he knows
its size and shape.

Imagine if the entire Universe

was just the size of this room

and that space
wrapped around itself

so each wall was the passageway
to the wall opposite.

Looking around,
I would see myself fractured,

as if by a crystal,
into multiple copies,

and each version would be
slipped backward in time.

Backward in time.

Backward in time.

Is our Universe
a hall of mirrors?

[ Indistinct conversations ]

Astronomers have looked

for repeating patterns
of galaxies for years,

looking for evidence
that the Universe has an edge.

But they've never found any.

Jean-Pierre Luminet
is a senior scientist

at the Paris Observatory.

He's been fascinated
with the shape of space

ever since he was a child.

I was always interested
in shapes created by nature.

And while it's a nice idea

to imagine a typical snail
with a spiral, for instance --

and you know there are
spiral galaxies, for instance --

the question is,

why is this shape
gonna be also in the sky?

Freeman:
Jean-Pierre's passion

to discover
the shape of the cosmos

grew from
the groundbreaking work

of the great Albert Einstein.

His theory of relativity

showed that space
is a flexible fabric

whose shape is deformed
by matter and energy.

Einstein imagined the Universe
as a flat sheet,

stretching out to infinity.

But there's no reason
it can't also be finite

and curled up on itself.

[ Piano playing ]

Jean-Pierre realized he might
be able to tell the difference

between a finite
and infinite Universe

by thinking of the cosmos
as a giant musical instrument.

The cosmic microwave
background image

shows us the Universe the way
it was 13.7 billion years ago --

a hot liquid vibrating with
aftershocks of the Big Bang,

like water rippling
in a bathtub.

So in some way,

the Universe vibrated
like a piano or like a drum.

So, for instance, this is
equivalent for the Big Bang.

[ Discordant notes play ]

It's a complicated mixture
of many harmonics, okay?

And now we have
the fundamental harmonics,

which gives the pitch.

And after, the other harmonics
are like this.

[ Harmonious notes play ]

And so on, okay?

So, the full sound
that we can listen to

is a mixture
of all these harmonics.

Freeman: But the number
of harmonics you can hear

depends on the size
of the piano.

The size of any musical
instrument is finite.

And a string, for instance,
cannot vibrate on wavelengths

larger than the size
of the string.

So, maybe, if we observe
that the Universe

didn't vibrate
on very long wavelengths,

maybe the explanation is
that space has a finite size.

Freeman: When Jean-Pierre
analyzed the ripples

in the cosmic microwave
background,

he found that the longest
wavelength ripples

were, indeed, missing.

We are surprised because
there was missing wavelengths,

missing fluctuation,
missing low tones --

you know, like low notes.

Low like this, okay?

They are missing
from the cosmic squall.

Freeman:
Jean-Pierre's passion for music

gave him a profound
cosmic insight --

that the Universe
appears to be finite.

But what shape could it be?

Jean-Pierre spends months

carefully testing different
shapes for his finite Universe,

trying to make it fit
the vibrations

of the cosmic microwave
background

as closely as possible,

until, finally,
he finds the perfect fit...

...A 12-sided dodecahedron...

A soccer ball.

Here in my hands here are two
different kinds of dodechahedra.

The first one is just
an ordinary dodechahedron,

namely 12 pentagonal faces

arranged
in a symmetrical manner.

This is a figure known
since antiquity.

You see that the Pentagons
are flat, okay?

Here, you have a different
styling of the sphere.

You see that the Pentagons
are curved, okay?

So this is called
the circle dodecahedron.

Freeman: If Jean-Pierre is right,
the shape of the Universe

is a lot more complex than a
six-sided "Asteroids" game cube.

The Universe has 12 sides,

and leaving one face leads you

to a matching Pentagon
on the opposite side,

but with a twist.

This edge is exactly the same
as the opposite edge.

So, as soon as you
get to this point,

you re-enter your space
on the opposite side,

and, in addition,
you have to turn by 36 degrees.

Freeman: If the Universe
were a dodecahedron

only slightly bigger than Earth,

light would zip around it
in minutes,

and you would see
twisted copies of Earth

in a dozen different directions
in the sky.

But if the edges of
Jean-Pierre's dodecahedron

are billions
of light-years apart,

the distant and faint
reflections on them

could have escaped the notice
of the most careful astronomers.

And if the edges lie further

than 13.7 billion light-years
from Earth,

we would never be able
to see them

because our view
would be blocked

by the hot soup of
the cosmic microwave background.

As soon as Jean-Pierre
announced his results,

Neil Cornish
begins looking for signs

of his colossal soccer ball.

He's a key scientist

on a NASA spacecraft
called WMAP,

which spent five years
photographing

the cosmic microwave background
in unprecedented detail.

So, here's a possible
model of the Universe

based on a dodecahedron.

Inside, we have a balloon

representing
the visible Universe,

how far we can see.

And if it was like this,

where the balloon is
much smaller than the space,

there would be no signs that we're
living in a finite Universe.

[ Air hissing ]

But if the visible Universe
was so large

that it actually touched onto
the edges of the dodecahedron,

then light would actually
be able to travel,

wrap right around the Universe.

So now we would have
these matching circles

on the microwave sky

where these two spheres
intersect to form a circle.

A circle here matching
the circle down here.

Now, we have looked

at the microwave background data
from the WMAP satellite,

and we haven't seen this pattern
of matching circles.

Freeman:
But Jean-Pierre Luminet

is not ready to give up
his soccer-ball Universe.

His ideas have triggered
a scientific battle

that spans continents and years
of meticulous work.

At stake is nothing less than
the truth about where we live,

where we came from,

and whether our Universe
is alone.

Einstein said,

"only two things are infinite --
the Universe and human folly."

But he admitted he couldn't
be sure about the Universe.

In fact, we are now faced
with tantalizing hints

that our Universe
may not stretch on forever,

that there is a point out there

where the Universe as we know it
does not exist.

It's an almost frightening
thought.

But before we try to grasp

just what might lay
beyond that final boundary,

we need proof.

Glenn Starkman
is a Canadian physicist

at Case Western University
in Cleveland.

He's taken data analysis
to new heights

in search of that proof.

Call him an information junky.

The joke about Canadians
is that you go to an airport

and you put up a sign --

"free sex to the right"

and "free information on sex
to the left" --

and the Canadians are all
the ones that go to the left.

I hope I'm not that boring.

Freeman:
Glenn had been poring

over cosmic microwave background
data from the WMAP probe

for most
of the past seven years.

Along with Neil Cornish,

he's been trying to test
Jean-Pierre Luminet's prediction

that the shape of space
is like a 12-sided soccer ball.

I would have been really happy
to find the pattern of circles

that the dodecahedron
told us would be there

if the dodecahedron was small,

and we looked for
and we didn't find.

Freeman:
But all of their tests assumed

that the edges
of the soccer-ball Universe

are closer than the microwave
background that blocks our view.

Now Glenn believes
he's found a way

to detect the edge
of the Universe,

even if it lurks beyond
the area we can see.

What you have to understand

is what is this actual pattern
of hot and cold spots

that we're seeing on the sphere.

And what it really is
is sound waves

that were traveling through the
Universe when it was very young.

So you can imagine it like
stretching the top of a drum.

At the same time that
as it was stretching,

it was actually making the drum
vibrate a little.

Freeman: Different-shaped Universes,
like different-shaped drums,

should leave different patterns
of vibrations

on the early Universe.

So, what we're gonna do is
we're gonna look at

some different-shaped
and different-sized drums,

and what we have over here
is a spectrum analyzer.

And Tom has set things up
so that when we make some sound,

we're going to get some traces
on this computer screen.

So let's start with our
nice, round, little drum.

[ Drum beats ]

Now let's go with
our heart-shaped drum.

It certainly sounded
a little bit different.

[ Drum beats ]

Finally, we have
a star-shaped drum.

[ Drum beating ]

When we superimpose the patterns
of those three small drums,

we'll see that they're not
quite exactly the same.

They have different patterns

and so we can
tell the difference

between one small drum
and another.

In the same way,
what we're planning to do

is use a spectrum analyzer

to look at the different sounds
that the Universe made

and to tell what the shape
of the Universe is.

Freeman: Glenn's analysis involves
such complex mathematics

that he imagines it will take
years to find the answer.

I will be incredibly excited

if we turn out to find
Jean-Pierre's dodechahedra.

It will be like discovering
that the Earth is round

rather than flat.

Freeman: But this scientist
is not waiting for data

to answer
this monumental question.

Andy Albrecht, a theoretical
physicist at U.C. Davis,

is sure the Universe is finite.

He even thinks
he can calculate its size.

Andy studies the very first
moments after the Big Bang,

when space was nothing more

than a seething,
chaotic ball of energy.

Suddenly, a process
called inflation takes hold.

It balloons up the Universe
at an incredible rate,

doubling its size 100,000 times.

A fraction of a second later,

all space and matter
is smoothly spread out.

Most scientists believe

inflation is still
happening today.

The going way
of thinking about inflation

is that it gives us
a truly infinite Universe.

The inflation itself never ends.

The more I thought about what
that infiniti might really mean,

the more I realized
it probably didn't make sense.

Freeman: So, Andy began working
on a new theory of inflation,

without infinities.

It's dizzying mathematics,

dealing with the laws of physics

before the Universe
as we know it existed.

But at its core,
it all boils down to bubbles.

A random process
starts the formation

of the bubble
that is our Universe.

I will be the random process
and blow the bubble.

Freeman: The traditional view
of inflation

imagines this bubble
inflates forever.

But Andy now takes the lessons
he learned in kindergarten

as a serious insight.

A bubble can only grow so big
before it pops.

Andy believes
inflation must stop

when space gets
to a certain maximum size,

and his pioneering theory
predicts that size.

The Universe is actually
just about 20% bigger

than what we see
around us today.

When I first started
trying out those ideas,

it was really difficult
to go all the way from infinity

to such a small thing,
just a little bit larger --

just 20% larger than what
we see around us today.

I actually felt claustrophobic.

Freeman: But if Andy's
new theory is right

and inflation
does not go on forever,

our Universe could look
something like this --

a large bubble surrounded
by a cluster of smaller ones.

Most cosmologists
think inflation

is the best explanation
for the even spread of galaxies

across our visible Universe.

But far out in space,

there may be regions where
inflation never took place.

Find those,
and you could be the first

to find evidence
of the edge of the Universe.

The eternal dance
of light in the night sky --

it has fascinated humankind
for thousands of years,

given birth to Gods, myths,

and, finally, to science.

But now there are hints
of strange movements

in the heavens.

If they can be verified,

they'll be the first
hard evidence

that there is an edge
to the Universe.

Sasha Kashlinsky
is a NASA astronomer.

He claims to have detected

a pattern of movement
in the heavens so bizarre

that it could revolutionize
our theory of the Universe,

just as the Big Bang once did.

We're here
at Glendale Golf Course

near NASA's
Goddard Space Flight Center.

And we came here
to simulate the Big Bang.

So let me try and do that.

As you see, the balls,

they just move away
from the mutual center.

Freeman: This even
spreading-out of galaxies

from a central
explosive beginning

is what astronomers see
when they look at the night sky.

But Sasha wanted to check
more precisely

how fast and in what direction
galaxies are moving

to see if there might be
any subtle deviations.

He used an effect
that can only be seen

when clusters of galaxies
are colliding.

The gases around them get heated
to millions of degrees.

When light from
the cosmic microwave background

passes through that hot gas,

it gets subtly altered.

How much it changes
depends on exactly how fast

the gas and the galaxies
it surrounds are moving.

But the change is tiny

and almost completely buried
in background noise.

For each individual cluster,
this is a very tiny amount,

and it gets drowned
by the noise.

But if you have many clusters,
you can beat down the noise,

but it's exceedingly difficult.

Freeman: Sasha methodically
worked his way

through a catalog
of galaxy clusters

from an orbiting
X-ray telescope,

checked their precise position
using ground telescopes,

and then carefully lined them up

with the cosmic microwave
background.

Oh, we were quite shocked

when we saw these results
at first.

In fact, so much that we didn't
know what to do with it.

We kept checking and checking.

We sat on the data
for a year-plus,

just checking everything,

because it just
didn't make sense to us.

Freeman: What Sasha's data
showed was almost unbelievable.

All the galaxy clusters,

no matter where they were
in the sky,

were all veering off
to one side of the Universe.

It was as if
they were being pulled

towards a mysterious attractor
beyond the visible edge.

He called it "dark flow."

We called it "dark flow" because

the observed distribution
of matter in the Universe

cannot account for this motion.

Freeman:
But if nothing Sasha could see

was pulling the galaxies
to one side,

what could be responsible
for the effect?

The answer could be
the edge of the Universe.

Kashlinsky: If you live
in this part of the world,

then, at first, you would
imagine that the entire world

is as flat
as what you see locally.

But if you were to look
sufficiently far away,

you may discover that the world

is very different
from what you see locally.

Freeman: Cosmologists,
ever since Einstein,

have thought of the Universe
being like a flat putting green

that extends on forever.

But dark flow could be hinting
that our Universe

is a finite space...

Surrounded by stranger terrain.

So, this was Big Bang
on a flat surface.

So, now let's go to a different
part of the world.

The balls did, indeed, disperse,

but, in addition,
they also have another velocity,

which is associated
with the tilt of this surface.

They move collectively
and systematically

from the higher ground
to the lower ground.

Freeman: Sasha's discovery of a
collective, systematic movement

of galaxies
to one side of the cosmos

has shaken
the field of cosmology.

Some scientists
refuse to believe it.

But for this woman,
dark flow was entirely expected,

and her ideas about the Universe

are even more mind-bending
than Sasha's.

She believes
she's found evidence

that another Universe is
reaching out and touching ours.

Scientists have discovered a
mysterious dark flow of galaxies

all veering off
to one side of our Universe.

It could be a sign that way out
beyond that furthest star

lurks a portion of the cosmos

vastly different
than the Universe we know.

But there's an even more
shocking possibility.

Dark flow could be evidence

of another Universe
reaching out to us.

That's what
theoretical physicist

Laura Mersini-Houghton thinks.

The seed of this idea
was planted many years ago

when she realized she had
a problem with the Universe --

a pretty big problem.

According to her calculations,

the Universe should not exist.

The chances
to start the Universe

with the high-energy Big Bang

are one in 10
with another 10 zeros behind it

and another 123 zeros behind it.

So, pretty much, zero.

So whenever in science
we end up with an answer

that "this seems very unlikely.

This event is not generic,"

then it usually indicates

that we have blundered
in something very basic.

Freeman: But Laura had an idea
of how to stop the Big Bang

from being
such an unlikely event.

You might call it
a gambler's hunch.

If you're playing a slot machine

where the odds
of hitting the jackpot

are 1 million to one,

you could play all day
and never strike it rich.

But if all 6 billion people
on Earth

each played
their own slot machine,

someone somewhere
is going to get rich

about once every few seconds.

Laura realized that one branch
of theoretical physics

offered a way to turn
the Big Bang into a sure bet.

It was string theory.

This view of reality suggests

that alongside the normal
three dimensions of space,

there are another seven
hidden dimensions

wrapped up so tightly,
we cannot see them.

Mersini-Houghton:
You start wrapping up

those extra dimensions,
the extra seven dimensions.

There are so many ways
of doing that process.

String theorists ended up

with not just one
3-dimensional world,

but with many, many possible
3-dimensional worlds.

Freeman: In fact,
string theorists realized

there were 10 to the power
of 500 possible ways

to arrange these dimensions.

That's a one
with 500 zeros behind it,

a number countless times bigger

than the odds
against our Big Bang.

The only way we can ask
the question

about the origins
of the Universe

is if we have
a multiverse structure

from which our Universe is born,

a landscape of many possible
places in this multiverse

where the Universe
can start from.

Freeman: If each of these balls
of wrapped-up dimensions

is an energy site
where a Universe could start,

then the odds of a Big Bang
happening in one of them

is no longer
an enormous long shot.

In fact,
the odds are good enough

that Laura's willing to bet
this landscape

should contain many Big Bangs
and many Universes.

You can think of this
multiverse landscape

as the biggest hotel
you can imagine,

a hotel with
10 to the power of 500 rooms,

each one waiting
for a guest to check in.

Mersini-Houghton:
Every room would represent

an energy site
of that landscape.

There is an infinite
number of people

that can try to check in
into these hotel rooms.

I try to go into a room,

and I discover
that energy site is taken.

Someone else is there.

Once a Universe is born
in that energy site,

first, that energy site

cannot be shared
with another Universe.

So I try to go to the next room.

Until I find an empty room.

That room is really boiling hot,
so it contains a lot of energy.

Once I am in the room,
I cannot get out of it anymore.

The door is locked.
That's how the Universe is born.

Freeman: But if our Universe
is like a hotel room,

shouldn't we be able to detect
the presence of guests

in the room next door?

That earth-shattering evidence

could look as subtle
as this small blue patch.

In 2007,
data from the WMAP spacecraft

confirmed the presence
of a strange, cold spot

in the cosmic microwave
background.

If I have
an empty region of space,

that would show
as a cold temperature region.

In the case of the cold spot,

the only way
such a part of the sky

could just be completely,
entirely empty,

that kind of bizarre behavior
of the Universe

can occur only if there
is some other force at work.

Laura believes the cold spot

is evidence of another Universe
right next to ours,

its enormous mass pulling on
matter at the edge of our world.

Mersini-Houghton:
If there are some very massive
objects in the next room --

in other words,
in the neighboring Universe --

then I should be able
to feel that gravitational pull,

although I cannot
directly see it.

Freeman:
But for a theory as radical

as the existence
of another Universe,

the cold spot alone
is not enough.

Laura needs more evidence.

And help is at hand.

Two scientists
are about to join forces

in a remarkable endeavor

to find the size and shape
of our Universe

and the Universe next door.

Is the Universe infinite?

Or does it have an edge?

Or is our Universe
just one member

of a cosmic family of Universes,

spread across a strange
and uncharted landscape?

Just a few years ago,

even asking these questions
was unthinkable.

Now we're close
to finding the answer.

Sasha Kashlinsky is convinced

that some mysterious attractor
at the edge of our Universe

is pulling on galaxies,

forcing them to move
with what he calls "dark flow."

His work is still controversial,

and to convince the skeptics,
he needs more data.

We hope, in a few years,

to have a catalog of up to 2,000
galaxy clusters in total.

And with the new data,
we hope that we'll be able

to measure the flow
to much larger scales.

Freeman: But Sasha now has
a powerful ally.

1,000 miles away, in Toronto,

Laura Mersini-Houghton was
defining her own calculations

about the edge of the Universe

when she got a phone call
from her mother.

Mersini-Houghton: And she says
to me, "Did you see the news

"about something called
dark flow or another?

There was a NASA person there."

And I said, "No, I haven't."

So I went straight
into my computer

and found out that a team
at NASA led by Sasha Kashlinsky

had reported
they had seen the dark flow

of structure in the Universe.

That was exactly
in perfect agreement

with the prediction
we had made two years ago.

But what made it spookier
was that even the numbers,

the speed at which
those galaxies were moving

and the direction
into which they were moving

were in absolute
perfect agreement astronomically

with our predictions.

Freeman: Now Laura and Sasha
are both contemplating

just how this exotic landscape
outside our Universe

might behave.

Mersini-Houghton: I can think
of this board as the landscape,

the energy sites onto which

these wave pockets
of the Universe

will eventually settle.

Now, I have to send
the wave pockets

through that landscape,
through that board

in order to populate it.

Freeman:
Think of this marble

as the pulse of energy
that triggered our Big Bang.

Soon, another pulse of energy
comes along.

It falls into a different dip,

and a neighboring Universe
is born.

That Universe is not a place
we can ever go.

Its arrangement of dimensions

will be completely different
from ours.

But there is one way
we can sense its presence.

If the two Universes
are close enough together,

their gravitational attraction
will pull anything with mass

towards their respective edges.

That's why we see the cold spot

and that's why there's
a dark flow of galaxies

moving across the cosmos.

This other Universe
is pulling on ours.

Until about three,
four years ago,

we knew nothing
of the multiverse.

However, things are
changing dramatically

in the last few years.

Technology is helping us
find signatures

of the existence
of the multiverse.

Freeman: But across the world
of cosmology,

the reactions to these
scientists' controversial work

is mixed.

If any one of them is right,

the implications
would be enormous.

Why do we even care about the
size and shape of the Universe?

That part of the story
is critical

for our attempts to understand
how it all came into being,

why it is the way it is,

and why we see
what we see around us.

All these questions have
very different answers

if we're looking
at the infinite story

or the finite story.

We'd be able to say,
"Look, here is the Universe.

This is its shape.
And that's where we live."

And that's a revolution
in physics --

going outside our Universe,

at least with the power
of our imagination.

But then that's what makes
human beings special.

Freeman:
Every now and again,

our perception of the Universe
and our place in it

undergoes a revolution.

We used to think the Earth
was the center of all creation.

For the past century,

we've learned to accept
that we live

in a nondescript region
of a backwater galaxy

in a Universe
that is unimaginably vast.

Now it's time for another change
of perspective.

Our Universe itself,
once assumed to be infinite,

might have to shrink down
and take its rightful place

as a humble member
of a truly giant multiverse,

a multiverse filled
with Universes

beyond our wildest imaginations.

== sync, corrected by elderman ==