Through the Wormhole

All around the Universe, stars are exploding.

They are cosmic catastrophes.

But to these scientists,

they are beacons in the depths of space.

They illuminate an epic battle

between two mysterious and invisible forces.

To one we owe our very existence.

The other is trying to tear us apart.

Now we're in a struggle of our own

to understand these colossal forces,

to learn to see beyond the darkness.

Space, time, life itself.

The secrets of the cosmos lie through the wormhole.

You, me, the sun, stars --

everything we see has one thing in common.

We're all made of atoms.

Atoms make up almost all the matter in the known Universe,

but...There is a whole lot more to the cosmos,

a side we're only just beginning to see.

Our bodies, our homes, our world,

even the vast void of space

is teeming with a mysterious substance...

...A form of matter so strange

that many scientists once doubted its very existence.

But in 2009, an incredibly sensitive particle detector

caught the first glimpse of it.

It's an Earth-shaking discovery,

and it's forcing us to radically reassess

our place in the Universe

and even our eventual fate.

As a boy, I used to lie in my room at night,

gripped by fear that something was out there in the darkness.

Was that a demon...

Or my clothes slung over the back of a chair?

I'd shine my flashlight at the furthest corner of the closet,

hoping to catch the phantom presence I sensed lurking there.

Well, I never did find anything in the shadows.

But just because you can't see something

doesn't mean there's nothing there.

In the 1960s, a young astronomer called Vera Rubin

decided to explore an area of space that was little-studied.

I had 2 children, one almost 2 and one almost 4,

and I didn't like the idea

of competing with astronomers for real hot topics.

Vera Rubin knew

if she studied something sexy, like black holes,

other astronomers would end up beating her to publication.

So instead she began surfing the galactic backwaters.

I'm not sure I really know

why I was studying galaxies,

except they seemed very mysterious to me,

and there was not a lot known,

especially about their motions -- almost nothing.

Vera first trained her telescope

on the Milky Way's closest galactic neighbor, Andromeda.

Like most galaxies, it had a dense central bulge of stars.

She expected the billions of stars

circling around this central bulge

to orbit just like the planets in our solar system,

obeying Isaac Newton's laws of gravity.

The further away they are from the center,

the slower they orbit.

This is a model of the solar system

that my father built for me

about 40 years ago, when he retired,

that shows exactly what Newton knew from his theories.

The four that you're seeing here --

Mercury, Venus, Earth, and Mars --

Mars is going the slowest, the Earth the next slowest.

Mercury is the most rapidly moving.

Because the force of gravity is considerably less for Mars

than it is for Mercury,

the orbit is correspondingly slower.

This is exactly the pattern Vera expected to see

when she studied stars as they orbited in their galaxies.

The further from the center, the slower they should be moving.

But that's not what Vera found.

It took us about two years

to get velocities of 90 stars in the Andromeda galaxy.

And the results were rather startling.

We found that all of the stars

were moving at the same velocity,

the same number, 250 kilometers per second.

For the next few years,

every galaxy Vera looked at

gave her the same seemingly crazy results.

All the stars all the way to the edge of the galaxies

were moving at the same speed,

completely different from the way the solar system works.

The only explanation

was that the force of gravity did not get weaker

the further a star was from the center of a galaxy.

But that could only happen

if the galaxies had more mass than astronomers could see.

The explanation was that there must be

very significant amounts of matter that are invisible.

In fact, perhaps 90% or 95% of the material in the galaxy

is invisible.

This was a truly revolutionary idea.

Galaxies might be filled with an unseeable substance,

something scientists could only think to call "Dark Matter."

But such a radical theory demanded ironclad evidence.

Soon dozens of astronomers were checking Vera's observations,

either struggling to disprove her

or scrambling to discover

what or where this mysterious Dark Matter might be.

I did find it amazing, and amusing,

that I had picked this field because I was interested

in doing something that no one would care about,

and suddenly I was involved with lots and lots of astronomers

who had ideas and observations, and it was a hot topic.

Across the Atlantic in England,

leading cosmologist Carlos Frenk

began to investigate the idea of Dark Matter,

using not telescopes but equations.

Take Newton's laws of gravity and feed them

into a highly sophisticated computer simulation...

Then go for lunch.

This is the cosmology machine, a very large supercomputer

whose only purpose is to simulate the Universe.

It's made up of 1,300 computers all working together.

Even then, it takes months

to complete a simulation of a small part of our Universe.

This is awesome computing power almost beyond imagination,

but that's what it takes if you want to emulate the Universe.

Carlos started out his simulation

with what scientists think the early Universe was made of --

a giant cloud of gas floating in empty space.

Then he sat back and waited

to see if his cosmology machine could build a galaxy

like the ones we see.

What happens if you try to make a galaxy in a computer

using simply the material that we can see?

What happens is, you end up with a failed galaxy.

Stars form, they evolve,

the biggest ones explode as supernovae,

and they inject so much energy.

But there just isn't enough gravity

to keep these gases together,

so the galaxy essentially blows itself apart.

The gas dissipates, leaving very little behind.

This is not how our Universe is made.

So Carlos started to add Dark Matter to his equations --

first a little, then more,

and eventually five times as much of it as visible matter.

After several weeks,

something strange came out of the cosmology machine --

strange because it was so familiar.

This is a computer simulation of the formation of the galaxy,

now with invisible Dark Matter and gas, shown here in green.

About a billion years after the Big Bang,

clumps of Dark Matter formed.

Gas fell into these clumps, turning to stars.

But attracted by the force of Dark Matter --

invisible Dark Matter, gravity --

these clumps came together,

fused to build ever larger structures,

so that 10 billion years later,

a beautiful spiral galaxy like our Milky Way was formed.

Carlos has shown

that galaxies should form when filled with Dark Matter.

But is there any way to prove

that this is what actually happened?

In Edinburgh, Scotland,

Richard Massey is still trying to answer that question

and is pioneering a new way of detecting Dark Matter --

gravitational lensing.

It's all thanks to the genius of this man.

Albert Einstein saw space in a new way --

as a bendable, malleable material

that is influenced by gravity.

Anything that has mass -- a star or a galaxy --

can bend the fabric of space and act like a lens.

As it bends space, so the light traveling past it is also bent.

Dark Matter doesn't reflect light,

it doesn't absorb light, it doesn't emit light.

Light just passes straight through it unaffected.

So we have to look for something else --

the way it affects, gravitationally,

things around it that we can see.

Now, this idea of light being deflected and bent

by warped space-time sounds crazy,

but actually it's very familiar.

We see light being bent all the time --

every time you look through the bottom of a wineglass.

Let me show you what I mean.

Although the bottom of the wineglass is transparent

and light passes straight through it, you know it's there

because of these distorted images in the background.

Dark Matter is exactly the same.

It bends light, through a different physical effect,

but the net result is the same -- that these images

of very distinct galaxies appear distorted

whenever there's some Dark Matter in front of them.

For two years,

Richard has been leading a team of international astronomers

and directing a fleet of telescopes

to scour one section of the night sky

for every single visible gravitational lens arc.

So, what we're seeing here is gravitational lensing in action.