Original subtitles

Male narrator: In the beginning, there was darkness,

and then, bang,

giving birth to an endless expanding existence

of time, space, and matter.

Every day, new discoveries are unlocking the mysterious,

the mind-blowing, the deadly secrets

of a place we call The Universe.

As they try to unravel the mysteries of the universe,

scientists are coming to an astounding conclusion.

To make sense of outer space,

they need to understand inner space,

the microscopic matter

that forms the foundation of everything we see.

But shrinking down billions of times,

into the realm of atoms and subatomic particles,

takes us into a strange unexplored world.

- When we descend into the microscopic world,

we find that it's really weird,

and indeed downright bizarre and unbelievable.

Narrator: The stuff in this universe

is far smaller than anything we can see with a microscope,

but it holds the key to the cosmos.

- We can only understand where we came from

if we understand this crazy micro world.

Narrator: So let's go on a fantastic voyage

into an uncharted world

known as the microscopic universe.

[dramatic music]

♪ ♪

When people talk about the universe,

they usually mean the vast expanse of space

billions of light-years across

that they can see with radio telescopes

and cosmic imaging.

- They think about stars and galaxies and planets

and all the big stuff out there.

- You have astronomical bodies

moving under the force of gravity.

- There are laws of nature,

and you think that the laws are right,

once and for all.

Narrator: However, there is another universe,

an unseen world that governs everything we see.

- When we go down in size trillions of times smaller

to the microscopic world,

the rules are much less intuitive

than the ones we're used to from the large-scale world.

Narrator. The magic of the microscopic universe

begins at about a ten-billionth of a meter,

or the size of an atom.

Matter behaves so differently at this level

that scientists have developed an entirely new set of rules

to describe what's going on.

They call it quantum theory.

And what it says is extraordinary.

- This baseball represents a subatomic particle,

like an electron or a photon of light,

that routinely does all sorts of weird, strange things

in the microscopic universe.

The subatomic version of this baseball

can be invisible,

can go through solid objects with ease,

can be in multiple places at the same time,

and can seemingly go backwards in time

and change the past.

This means I could throw this microscopic baseball

to first base and to home plate at the same time...

or change the seemingly predetermined outcome of a play

while it's still going on.

Now this—this is the stuff of science fiction.

But really, we know it to be true,

or at least, it appears to be true

in our quantum world.

We get all sorts of weird things happening.

Narrator: If scientists can understand

how these weird things work,

they'll be able to put them to use

in our everyday world,

revolutionizing modern computing,

and perhaps even allowing us

to communicate across the cosmos instantly.

The key to making these miracles come true

is a process called quantum entanglement,

and scientists are already harnessing

this astounding discovery

for both civilian and military purposes.

- In quantum physics,

what happens to an object over here

can instantly affect an object over here,

and over here could be millions of miles away.

Narrator: This is how it works.

When two subatomic particles interact,

they can become entangled.

That means their spin, position,

or other properties become linked

through a process unknown to modern science.

- If you then make a measurement of one of the particles,

then that instantaneously determines

what the behavior of the other particle should be.

And when the experiment is done,

it's found that, indeed,

the other particle's quantum state

is exactly determined once you've made a measurement

of the partner particle's quantum state.

Narrator: That means

if a scientist observes one entangled particle

and forces it to spin clockwise,

the other entangled particle

will immediately start spinning in the opposite direction.

That seems intriguing, but it's hardly earth-shattering

until you consider that the two entangled particles

can be separated by billions of light-years,

and still, the moment you observe one particle's spin,

you've dictated the other particle's spin.

- That's weird, because it may suggest

that information has traveled instantaneously,

faster than the speed of light,

from one particle to another.

I don't understand it. I don't know that anyone does.

"Spooky action at a distance," as Einstein called it.

Narrator: Quantum entanglement

is more than a curiosity of the microscopic world

because the effects of entangled particles

can be seen and felt in our world.

If scientists can overcome some fundamental obstacles,

quantum entanglement could someday help humans

communicate across vast distances instantly.

- People sometimes think that quantum entanglement

will achieve the desired goal

of transferring information

at a speed faster than that of light.

I don't think this will be achieved,

because to set up these systems,

you had to have brought them there

at speeds slower than the speed of light.

But then what do I know?

A hundred years ago,

they didn't think that we'd be going to the Moon.

Narrator: Quantum entanglement

is far more likely to transform modern computing.

Scientists hope to use the magic of the microscopic universe

to build powerful new computers.

- We're going to see what this baby can do.

Narrator: At the Massachusetts Institute of Technology,

Professor Seth Lloyd

has helped create a prototype of a quantum computer

which uses quantum bits

rather than traditional computer bits

to perform its calculations.

- This lab has the world's best superconducting quantum bit,

or Q-bit, in it.

And when we do quantum computations with Q-bits,

we can have the quantum computer

do multiple tasks simultaneously.

It can do this, it can do that

at the same time.

It can add two plus two,

it can add one plus three,

and it can add those two things simultaneously.

Narrator: The fact that a single Q-bit

can perform many calculations at the same time

gives the quantum computer the potential

to be far more powerful than any computer ever imagined.

Like traditional computers in the 1950s,

quantum computers are in their infancy today.

The machines take up large rooms

and can do only the most basic calculations.

But they hold great promise for the future.

- Quantum physics is notoriously weird,

strange, and counter intuitive.

And so quantum computers use this weirdness

to compute in ways that classical computers can't.

Narrator: The major stumbling block

is figuring out how to effectively code

classical information—

The ones and zeros that computers use—

In a way the microscopic universe can process it

using entangled particles.

But when scientists figure that out,

quantum computers could transform the planet.

- Even if you have a quantum computer

with not that very many bits,

you might still be able to do things

like break all the codes

that people use to communicate on the internet.

Or you could solve very difficult problems

having gajillions of variables,

like try to figure out

what happened at the big bang.

Narrator: That may be hard to believe,

but the microscopic universe gets even stranger.

In fact, the most famous experiment in quantum physics

shows how one object can be in two places at the same time,

a result that startled the great Albert Einstein.

As scientists explore the microscopic universe,

they find it's governed by rules

that are often incomprehensible

to those of us in the normal world.

At the smallest scales imaginable,

not only does information

appear to travel faster than the speed of light,

but human observation often seems to decide what happens.

- It seems like the behavior of quantum mechanical stuff

is different when we're looking at it

than when we're not looking at it.

Narrator: This profound conclusion

comes from performing the double-hole experiment.

Scientists first conducted this experiment a century ago,

firing photons of light through a metal plate with two slits.

The light that went through the holes

hit a screen behind the plate.

- I'm going to demonstrate the results

of this amazing experiment

with a bunch of baseballs

and a barrier that we've set up

which has two holes in it.

Now, normally, in the everyday world,

if I throw baseballs through one hole or the other,

they'll form a predictable pattern

on a screen that we've set up behind home plate.

They'll be in one place or the other.

Now, let's make that pattern with a whole bunch of baseballs.

I'm going to use this pitching machine.

Here's the first one.

Let's see what happens.

Now, you see?

The balls landed on the screen in two bunches,

pretty much along a direct line from each of the two holes.

That's natural. That's what we expect.

But when we descend into the microscopic universe

and use electrons,

which are 10 trillion times smaller than baseballs,

we get a very different, odd result

when we perform this experiment...

A pattern that you would expect if these were waves

going through both holes at the same time

and interfering with themselves.

Well, we usually think of electrons

as being particles.

So how can they exhibit wavelike properties?

Narrator: These test results were confounding.

The electron was a particle

before it was fired at the screen;

yet it formed a pattern on the screen

as if this single electron

had gone through both holes at the same time.

Does a microscopic particle

spontaneously clone itself in midair?

After years of study,

scientists still don't know exactly what's happening.

- Probably the most magical thing

is that in quantum physics,

an object can be in more than one place at the same time.

- It actually can sense both slits

and actually go through

and quantum-mechanically feel the structure

of both slits in the experiment.

- Most physicists agree that the math is quite solid

and leads to solutions that are undeniable

and can be confirmed with experimental measurements.

But exactly what is happening, and how,

is a matter of debate.

Narrator: To try to grasp

this amazing experimental result,

scientists decided to observe how individual electrons behaved

when they went through the double slit.

How exactly could a particle go through both holes

at the same time?

- Scientists got a front-row seat

to observe the strange behavior of these electrons

or other subatomic particles or even photons of light.

Doesn't really matter, as long as they're small.

They didn't just look at where they landed

on the screen back there;

they also watched the behavior of the particles

as they went through the holes.

And then they saw something amazing.

When scientists were watching the holes,

the electrons behaved like particles,

forming the baseball-like pattern

on the screen back there.

But when the scientists weren't watching,

then the electrons behaved like waves.

They formed a pattern that looked like

the interference pattern produced by waves on a screen.

That's really strange.

What you see depends on whether you're watching or not.

If you're watching,

you see the particle-like behavior like baseballs.

If you're not watching, you see a wavelike behavior.

But not both at the same time.

Narrator: This was nothing less than astounding.

Observation seems to change

the nature of subatomic particles.

- Mysteriously, when we're not looking,

things are waves.

When we are looking, they look like particles.

So even an electron,

which seems to us like a particle,

has wavelike properties when we're not looking at it.

- The fact that when we don't look,

the electron appears to go through both holes,

but when we do look, we always see it

go through one hole or the other

is what we call the quantum enigma.

Narrator: How could our decision

about whether to observe something

change how that something acts?

There is a technical explanation.

- To make an observation,

you somehow have to interact with a system.

For example, you have to shine light on it,

which then bounces off, and you observe the light.

That's how we can tell that a baseball is here or there:

we bounce light off of it.

Well, for macroscopic particles,

that doesn't disturb them very much.

But for microscopic particles,

the act of bouncing the light off of the particle

changes where it is and how it's moving.

Narrator: So in the microscopic universe,

where photons of light are about the same size

as subatomic particles,

these photons have a big impact

when they illuminate the particles

SO we can see them.

But this doesn't answer the question

"Why doesn't the light

"simply change the direction of the subatomic particles?

"Why does observation actually change

the nature of what is being observed?"

- The short answer is, "We don't know."

This is the fundamental mystery of quantum mechanics,

the reason why quantum mechanics is difficult.

Mysteriously, when we look at things,

we see particles.

Then when we're not looking, things are waves.

- This is something

we scientists have argued passionately about now

for almost a hundred years.

And there's still no consensus.

Narrator. When they were first released a century ago,

these test results were enough to unsettle

the brightest mind in science.

- Einstein said,

"I don't believe in quantum physics,

"because I believe the Moon is there

even when I'm not looking at it."

Einstein was of course referring

to the implications of the theory

that the Moon really isn't anywhere

until it's observed.

Narrator. However, the double-hole experiment's

mind-boggling conclusions don't end there.

In recent years, technology has allowed scientists

to perform a fascinating variation of the test.

Its results call into question our perception of time itself.

- This is like a high-tech version

of the double-hole experiment.

Electrons are being fired toward a barrier

with two holes in it.

But the scientists can delay their decision

about whether to observe the electrons

until after they've passed through the holes,

but before they hit the screen.

It's as though I'm on a baseball field

and there's a baseball being pitched toward the barrier

with the holes in it.

But my eyes are closed,

so it goes through and it behaves like a wave.

But then, at the last second before it hits the screen,

I open my eyes and decide to observe it.

Narrator: At that moment,

the electrons, in essence, become particles

and seemingly always were particles

from the time they left the electron gun.

- So it's as though they went back in time

to before they went through the holes

and decided to go through one or the other,

not through both, as they would have,

had they been behaving like waves.

That's really crazy!

- That's the enigma:

that our choice of what experiment to do

determines the prior state of the electron.

Somehow or other we've had an influence on it

which appears to travel backwards in time.

Narrator: Scientists are only beginning to grasp

what these microscopic mysteries mean for time travel

and changing the past in our everyday world.

But one thing is clear.

The rules that govern this subatomic world

hint at a universe that's just as mysterious

as science fiction.

In fact, quantum physics may suggest

that reality is simply a figment of our imagination.

After discovering mysteries in the microscopic universe,

scientists wanted to quickly unravel,

study, and solve them.

But as they tried to figure out exactly what was going on

in this strange subatomic realm,

they found something completely unexpected.

Nature refused to tell them.

- When we descend into the microscopic world,

we find that there's a fundamental uncertainty

in essentially all quantities that we wish to measure.

And it's not a problem with the measurement process.

It's that nature herself does not know.

Narrator: Scientists call this the uncertainty principle.

And as strange as it is,

it may be the most profound concept

to emerge from the microscopic universe.

We simply cannot know anything with absolute certainty.

- In our everyday world,

we think we know a lot about the things around us.

We can actually locate, for example,

the position of this cue ball

and strike it at a certain speed,

which we know,

and we can use that to collide it into other balls,

and go ahead and play a game of pool.

But what actually happens

if we shrink everything down trillions of times?

In that world, these pool balls

are now actually like subatomic particles.

Narrator: In this microscopic realm,

quantum physicists have found

they simply cannot determine with any precision

where these particles are located

because of their wavelike qualities.

And what's even stranger:

if scientists try to box in a particle,

it will always generate enough energy

to break out of the box

before its position and speed have been determined.

The uncertainty principle says

nature will not allow its fundamental elements

to be boxed in.

- So because in the microscopic world—

Because particles will interact

with a completely different set of rules,

the rules of quantum physics,

microscopic pool will be a completely different game.

Narrator: The uncertainty of the microscopic universe

extends far beyond the location of particles.

It applies to everything, including a particle's energy.

And this gives rise to a stunning phenomenon

called quantum tunneling.

- In classical physics,

if you throw a ball at a wall

and you don't throw it hard enough,

it won't go through the wall; it will bounce back.

But if it's an electron

and you don't throw it hard enough

to go through the wall,

it might go through anyway.

We call that quantum tunneling.

Narrator: How can this be possible?

It may sound bizarre,

but one way to explain quantum tunneling

is that the uncertainty of the microscopic universe

allows a particle to borrow energy

from the future to breach the barrier

and then pay it back

after it gets to the other side.

- The electron actually already is

on the other side of the wall,

and therefore, it can go through it

and appear on the other side of the wall.

Narrator: Ever since these wonders

of the microscopic world were discovered a century ago,

people have asked if quantum tunneling—

Being in multiple places at the same time

and what appears to be traveling backwards in time—

Can be achieved in our everyday world.

Some scientists say we'll never be able

to throw a baseball through a solid barrier.

- A baseball is a huge number of particles.

You would need all of them

to collectively suddenly appear in another place

for the baseball, as a whole, to appear in another place.

And that's just extraordinarily unlikely.

A single electron or a single proton can do this.

But the bigger your particle,

or the bigger the collection of particles,

the more difficult that process of tunneling is.

Narrator. However, a growing number of physicists

are developing a more outrageous theory

for what's going on.

- We know that these tiny particles

can be in two places at the same time.

But, hey, I'm made of these kinds of particles.

So if they can be in two places at once, so can I.

Narrator: Scientists call this

the many-worlds interpretation of quantum physics.

They say, just like the electron in the double-hole experiment,

human beings are all in multiple places at the same time.

They say anytime anyone makes a decision,

we don't actually choose one option over another.

Instead, we do them both,

in slightly different versions of reality.

- What happens when you use your mind

and your will to decide things is,

you end up actually making many choices at once,

and all of them become realized in different parallel universes.

- The many-worlds hypothesis of quantum physics

says that when I throw a curve ball,

I do so only in this universe.

In another universe, I might be throwing a fastball.

And in still another one, I throw a knuckle ball

for the first time in my life.

And in yet another universe,

I heave this ball to the outfield.

In the many-worlds hypothesis,

all of these choices are outcomes

that occur in universes that are parallel to our own—

Just not in ours, but in parallel universes.

That's what the many-worlds hypothesis tells us.

Narrator: This may sound far-fetched,

but an impressive array of theoretical physicists

believe it's the way the microscopic world works.

If it's true, the implications of this startling theory

go far beyond the baseball diamond.

In essence, it suggests there are universes

parallel to our own in which

the Nazis won World War I will.

And in another, the American government

foiled the 9/11 hijackers.

So the world trade center still stands in Manhattan.

- If you take quantum mechanics absolutely at face value,

it says that every time you observe

something quantum-mechanical,

you become two different copies of yourself.

There's the copy that got one answer

and a copy that got another answer.

It just implies there's a huge number

of other copies of you

that saw slightly different things happen

in the universe.

- These days, it's completely accepted

that the micro world is weird.

Many people had hoped that this weirdness

could be confined to the micro world

so that big things like us would be immune to it

and always be in a single place.

But it's become clear now that that hope...

[laughs] Was naive.

The weirdness can't be confined.

Narrator: The fascinating debate

about the many-worlds interpretation

of quantum physics

will rage until physicists finally solve

the mysteries of the microscopic universe.

However, some astronomers are concluding

that we will never be able to fully explain

any of these mysteries,

because, according to their calculations,

the vast majority of matter holding the universe together

exists in a higher dimension that we can never explore.

If there's anything in the microscopic universe

stranger than quantum particles,

it's the mysterious matter that scientists have never seen

but that plays a crucial role in the formation of planets,

solar systems, and galaxies.

- Astronomers know that there's all sorts of matter out there

that exerts a gravitational influence

but that we can't see.

We call that dark matter.

- I wouldn't exist if it weren't for dark matter,

because dark matter has this nurturing force

of bringing things together to form structure,

to form galaxies,

which are absolutely necessary for life.

Narrator: Dark matter makes up a staggering 85%

of the gravitationally attractive stuff

in the universe.

- If the dark matter is some kind of particle,

then typically, millions of dark matter particles

will pass through me every second.

Narrator: But even though they know dark matter exists,

astronomers have been confounded by a microscopic mystery:

what is it?

At first, they thought it was ordinary matter that,

for some reason, they couldn't see.

- But what happened was,

astronomers went and took an inventory.

We know how much ordinary matter there is in the universe.

By "ordinary matter," we basically mean atoms,

things that are made out of protons,

neutrons, and electrons,

the elementary particles that go into making you, me,

everything on Earth.

And it just doesn't measure up.

There's not nearly enough ordinary matter

in the universe to make up the total.

Narrator: This conclusion was bizarre.

How could most of the matter in the microscopic universe

not be made of protons, neutrons, and electrons?

- It's been quite shocking to discover

that these atoms actually make up

just a small minority of all the stuff in the universe.

There's six times more

of an altogether different substance

which is invisible to us.

- It's interesting to think that science has brought us

to the point where we realize

not only are we not the center of the universe;

we're not even made of the same stuff

as the universe is made of, for the most part.

Most of the stuff in the universe

is this dark matter,

and it's some small particle

beyond the reach of our direct detection.

Narrator: Some theoretical physicists

speculated that dark matter might be made of neutrinos—

Tiny particles

a thousand times smaller than an electron

that fit many of the known characteristics of dark matter.

- We know neutrinos exist.

And they have mass.

They contribute weight, so maybe we're done.

But now it's turned out that they're not neutrinos.

- Most of the dark matter is probably not normal neutrinos,

because they travel very, very quickly.

And they wipe out the formation

of what's called large-scale structure,

the clumping of material on the scale of galaxies,

early in the universe's history.

So it would be much harder to produce galaxies

if the universe is filled

with lots and lots of neutrinos zooming around.

- So the dark matter is not ordinary matter.

It's not neutrinos.

It's some wholly new kind of particle

that we haven't detected yet.

- It has to be some sort of weird subatomic particle

left over from the big bang,

when the universe was very hot and dense.

A whole zoo of particles was created.

Most of them annihilated or decayed into other particles.

But some were left over,

and they are what are thought to be the dark matter.

Narrator: But what could this exotic microscopic particle be?

Since it's nothing known to science,

astronomers proposed an entirely new particle

that embodied all of dark matter's characteristics

and then began searching the universe for it.

They call it a WIMP,

a Weakly Interacting Massive Particle.

- One of the problems with the WIMP hypothesis

is that we've never actually detected a WIMP in a laboratory.

- In fact, there's several experiments

going on right this minute

to look for WIMPS in underground laboratories.

And you'd also like to make them in particle accelerators,

like the Large Hadron Collider in Geneva.

So there's a multi pronged attack to detect WIMPs directly

if they're the right answer.

Narrator: If scientists find evidence of dark matter,

will they also find evidence of another world

of dark planets...

dark life-forms...

and a dark matter table of elements?

- I don't think they are like us,

in that the dark matter particles

can form planets and so on,

because if they could, then we would expect

most of the planets in our solar system

to actually be made of dark matter.

But I think it's much more likely

that the dark sector

is many different kinds of particles

that are much more complex than just one.

Narrator: However, modern science

still has not found evidence

of this mysterious microscopic material.

And a growing number of scientists argue

that's because it's not something else;

it's somewhere else,

like other dimensions.

- People have taken very seriously

the idea that the dark matter comes from other dimensions,

or represents ordinary particles

that are actually moving in the other dimensions.

The thing about other dimensions are,

we don't see them,

we don't interact with them very strongly,

so they're a natural place to put the dark matter.

- It's conceivable that the gravitational influence

in galaxies and clusters of galaxies

that we attribute to dark matter in our own universe,

is actually caused by concentrations of matter

in other dimensions

that are felt within our dimensions

but will never be discovered within our dimensions

because they're actually somewhere else.

Narrator: Whatever or wherever it is,

many physicists are confident

they'll eventually discover a complete solution

to the dark matter mystery...

unless, they say, it simply exists

at an incredibly small size,

far smaller than humans have ever been able to explore.

That raises the question:

"What does exist at the smallest scales

of the microscopic universe?"

That's what viewer Jason L. from Houston, Texas,

wanted to...

- Jason, I'm glad you asked that question.

The smallest things in the universe

are the fundamental subatomic particles,

like electrons

or the quarks that make up protons and neutrons

or neutrinos.

Now, all these particles are thought to be

different vibrational modes

of a little tiny entity called a string,

a little tiny package of energy.

And that, then, is the smallest thing

from which everything else is made.

Narrator: Scientists have just started

trying to explore strings,

and other incredibly small stuff in the microscopic universe.

And what they found offers tantalizing clues

to a world beyond.

As they delve into smaller and smaller spaces

in the microscopic universe,

scientists have successfully looked inside atoms.

But what exists if we continue our fantastic voyage

still deeper into this subatomic netherworld?

- Even scales that are smaller than the electron

are really a vast unexplored territory,

more so than solar systems or galaxies

or even the universe,

because we can make observations of planets and stars

and galaxies and the universe,

but it's hard to conduct experiments

that allow us to directly explore

tiny scales in time and space.

- Essentially, what you need to examine

the microscopic world is a sharper and sharper tool,

something that actually allows you

to distinguish the details down at that very small level.

Narrator: But as scientists

try to probe spaces smaller than the atom,

they cannot possibly focus enough light

to illuminate them.

They need something more powerful.

- To look more finely, you need more energy.

We can go to incredibly small details

using high-energy devices of various kinds.

Now, the state of the art

are actually particle accelerators.

We use elementary particles

to actually probe the structure of other elementary particles

by colliding them together,

letting them interact with each other

and then seeing what comes out at various energy scales.

So we can continue this process

of examining smaller and smaller distances

in space and time

by actually going to higher and higher energy

with collider experiments.

[explosion]

Narrator: However,

the world's largest particle accelerators

have not yet generated enough energy to probe things

much smaller than the elementary particles inside atoms.

Even so, scientists believe something exists

at even smaller scales,

at a size so tiny, the human mind

cannot possibly comprehend it.

- Physicists are now trying to understand

what's called the Planck length,

10 to the minus 33-power centimeters.

That's 20 factors of 10—

20 orders of magnitude smaller than an electron.

Now, an electron is yea big, and I exaggerate a lot.

So the Planck length is just almost unimaginably smaller

than any objects we can actually measure.

Nevertheless, physicists are trying

to deal with these scales.

And that's what string theory is all about.

- String theory says that everything

that we think of as a particle

is actually a tiny vibrating loop of string.

To get an idea of how tiny it is,

I have here an eyedropper.

We're going to put out one drop of water.

That has about a trillion trillion atoms

of hydrogen and oxygen.

Now imagine taking one hydrogen atom

and blowing it up by 10 billion times.

It becomes about 1/2 a meter across.

And you might say,

"Can we now see the individual strings

inside that hydrogen atom?"

But the answer is no.

We can continue to make it bigger,

make one hydrogen atom the size of the solar system.

The strings are still too small to be seen.

It's only when we make that atom

the size of our observable universe,

that a string becomes macroscopically large.

If one hydrogen atom is as big

as the whole observable universe,

how big is a string?

Only about the size of one of these trees.

The amazing thing is that we human beings

can even talk sensibly

about what exists at this microscopic scale.

Narrator. Not only can scientists talk sensibly;

they've also formulated theories about what happens down there.

- This is really one of the holy grails

of all of science.

- We think that ordinary space and time

cease to exist at the Planck length.

What we don't know is what takes their place.

We need to replace our idea of space itself

by something more fundamental,

something that might involve different numbers of dimensions

or just a different concept entirely.

Narrator: One possibility is that space at the Planck length

resembles the grid on a football field.

The yard lines are the fabric of our universe,

and there's simply nothing in between.

- It could be that time jumps

from one discrete point to another,

and there are no steps in between.

- And, like, little quantum mechanical ants

could tunnel from one spot on the grid

to another spot on the grid

without ever going

into the intervening space in between.

Why?

"Cause there isn't any intervening space in between.

Narrator: Whatever exists at this incredibly small scale,

most scientists believe that the concepts of space and time

segue into another kind of universe

where shrinking smaller is a meaningless concept.

- It could be that time and space

are what we call emergent properties

of the universe,

but that if you go to very small spatial scales,

or very small intervals of time,

the concepts of time and space break down.

They don't make sense.

Narrator. Scientists say the conditions at the Planck length

may be very similar to those that existed

before the big bang,

when everything in our universe

was probably concentrated in a microscopic pinpoint.

- Maybe the same answers to the question

about what happens to the universe

at the very smallest scales

may also be connected to knowing,

what was the universe like before the big bang?

Did it just come into being at the big bang,

or was there something different

which then turned into the universe

that we're familiar with at the big bang?

These are all questions we don't know the answer to

but are all connected to the issue

of what's going on at the Planck scale.

- You might think that these tiny Planck-scale things

have nothing to do with us, who are much bigger.

But actually, it has everything to do with us.

It's our origins.

Our entire universe, if we extrapolate backwards,

would have been smaller than the Planck length.

Narrator: Whatever exists at the smallest scales

of the subatomic world, and however these things behave,

scientists say they must make sense of it all

before they can possibly comprehend the cosmos above,

human behavior,

and what might have existed before the big bang.

It's a mind-boggling amount of information

tucked inside an unimaginably small space

of our microscopic universe.