The Fabric of the Cosmos

WHAT IS SPACE? PBS Airdate: November 2, 2011

Lying just beneath everyday reality is a breathtaking world,

where much of what we perceive about the universe is wrong.

Physicist and best-selling author Brian Greene

takes you on a journey that bends the rules of human experience.

Why don't we ever see events unfold in reverse order?

According to the laws of physics, this can happen.

It's a world that comes to light

as we probe the most extreme realms of the cosmos,

from black holes

to the Big Bang

to the very heart of matter itself.

I'm gonna have what he's having.

Here, our universe may be one of numerous parallel realities.

The three-dimensional world maybe just an illusion

and there's no distinction between past, present and future.

But how could this be?

How could we be so wrong about something so familiar?

Does it bother us?

Absolutely.

There's no principle built into the laws of nature

that say that theoretical physicists have to be happy.

It's a game-changing perspective

that opens up a whole new world of possibilities.

Coming up...

What if you took all this stuff away?

We're left with empty space.

But what seems like nothing

is actually teeming with ferocious activity.

What is space?

It is one of the deepest mysteries in physics.

Could its elusive ingredients hold the key

to the fate of the universe?

"The Fabric of the Cosmos," right now on NOVA.

Major funding for NOVA is provided We think of our world as filled with stuff,

like buildings and cars...

buses and people.

And nowhere does that seem more apparent than in a crowded city

like New York.

Yet all around the stuff that makes up our everyday world...

is something just as important but far more mysterious,

the space in which all this stuff exists.

To get a feel for what I'm talking about,

let's stop for a moment and imagine.

What if you took all this stuff away?

I mean all of it:

the people...

the cars and buildings.

And not just the stuff here on Earth,

but the earth itself.

What if you took away all the planets, stars, and galaxies?

And not just the big stuff,

but tiny things down to the very last atoms of gas and dust.

What if you took it all away?

What would be left?

Most of us would say, "Nothing."

And we'd be right.

But strangely, we'd also be wrong.

What's left is empty space.

And as it turns out, empty space is not nothing.

It's something.

Something with hidden characteristics as real

as all the stuff in our everyday lives.

In fact, space is so real it can bend...

Space can twist...

And it can ripple.

So real that empty space itself helps shape

everything in the world around us

and forms the very fabric of the cosmos.

You can't understand anything about the world

unless you understand space

because that's the world-- the world is space.

With stuff in it.

We're not usually very conscious of space.

But then again, I tell people,

fish are probably not conscious of water either.

They're in it all the time.

Space is not really nothing.

It actually has a lot going on inside.

When most of us picture space,

we think of outer space-- a place that's far, far away.

But space is actually everywhere.

You could say

it's the most abundant thing in the universe.

Even the tiniest of things like atoms,

the basic ingredient in you and me and everything else we see

in the world around us,

even they are almost entirely empty space.

In fact, if you removed all the space

inside all the atoms making up the stone, glass, and steel

of the Empire State Building,

you'd be left with a little lump...

about the size of a grain of rice,

but weighing hundreds of millions of pounds.

The rest is only empty space.

But what exactly is space?

I can show you a picture of Spain...

of Napoleon...

of my Uncle Harold.

But space looks like this.

Nothing.

So how do you make sense of something

that looks like nothing?

Why is there space rather than no space?

Why is space three-dimensional?

Why is space big?

We have a lot of room to move around in.

How come it's not tiny?

Um...

We have no consensus about these things.

What is space?

We actually still don't really know.

It is one of the deepest mysteries in physics.

Fortunately, we're not completely in the dark.

We've been gathering clues about space for centuries.

Some of the earliest came

from thinking about how objects move through space.

To get a feel for this, take a look at that skater.

As she glides across the rink,

she's moving in relation to everything around her,

like the ice.

And when she goes into a spin,

not only can she see that she's spinning,

she can also feel it,

because as she spins, she feels her arms pulled outward.

But now let's imagine

that you could take away all the stuff around her,

from the rink...

to the most distant galaxies.

So the only thing left is the skater

spinning in completely empty space.

If the skater still feels her arms pulled outward,

she'll know she's spinning.

But if empty space is nothing,

what is she spinning in relation to?

Imagine you're that skater.

When you look out, you don't see anything.

It's just uniform, still blackness all around you.

And yet, your arms are being pulled outwards.

So you say to yourself,

what could I be spinning with respect to?

Is there something out there that I'm not seeing?

Trying to answer questions like these,

scientists came up with a bold new picture of space.

And the key was to make something out of nothing.

(actors reciting lines in distance)

When you go to the theater, you watch the actors...

I do confess that I love nothing in the world so well as thee.

...the scenery, the story.

I protest I love thee...

Well, then God forgive me!

What offence, sweet Beatrice?

But there's something important here

that you won't find mentioned in the playbill.

Something we hardly ever notice.

The stage.

It's an absolutely vital part of the show,

and yet most of us, we don't even give it a second thought.

But Isaac Newton, he did.

This is how the father of modern science pictured space:

as an empty stage.

To Newton, space was the framework

for everything that happens in the cosmos,

the arena within which the drama of the universe plays out.

And Newton's stage was passive--

absolute, eternal and unchanging.

The action couldn't affect the stage

and the stage couldn't affect the action.

By picturing space in this way,

Newton was able to describe the world

as no one had ever done before.

His unchanging stage allowed him to understand

almost all motion we can see around us,

yielding laws that can predict everything

from the way apples fall from trees...

to the path the earth takes around the sun.

These laws worked so well that we still use them

for the things we do today,

from launching satellites...

to landing airplanes.

And the laws all hinge on one radical idea: space is real.

Even though you can't see it or smell it or touch it,

space is enough of a real, physical thing

to provide a benchmark for certain kinds of motion,

like that skater.

Newton would say that when she spins, her arms splay out

because she is spinning with respect to something,

and that something is space itself.

Philosophers had been debating the nature of space

for a very long time.

What Newton does is change the terms of the debate,

and with that,

essentially, modern science gets born.

Newton's stage was a huge hit.

It enjoyed the limelight for over 200 years.

But in the early decades of the 20th century,

a new set of ideas emerged

that shook Newton's stage to its very foundations.

Ideas put forward

by a young clerk working in a Swiss patent office.