All language subtitles for Through.the.Wormhole.S05E10.When.Did.Time.Begin.720p.HDTV.x264-DHD

We all float
along the river of time.

But does that river
have a source?

How was time unleashed?

Some believe time
flows smoothly and eternally.

Others say
it doesn't flow at all --

it pops into existence
every fraction of a second.

The finest minds
in physics can't agree.

But new experiments
may hold the answer

to the greatest unsolved mystery
in the history of the universe.

The mystery...

Of when time began.

Space...

Time...

Life itself.

The secrets of the cosmos
lie through the wormhole.

-- Captions by vitac --
www.Vitac.Com

captions paid for by
discovery communications

When were you born?

Sounds like a simple question.

You just say a certain year,
a month, and day.

But around the world,
we reckon time differently.

In Saudi Arabia,
it's the 15th century.

In Israel, it's the 58th.

And we live in
24 different time zones.

We all measure time relative
to some starting point --

a point we have chosen.

But if we really want to know
what time it is,

we need to know when the cosmic
clock started to tick.

Did time begin
when the universe began?

Or did it start some other way?

Once, I was in a bike race.

I wanted to impress some friends
with my terrific speed.

So I gave it everything I had.

It was a close race -- so close,
I thought it was a tie.

One kid said
my opponent was quickest.

But another said I was faster.

So, whose perception of time
was correct?

In a way, we were all right.

Time is a measure of change.

But how do
we know things change?

We rely on what
our senses tell us,

and primarily,
we rely on what we can see.

We rely on light.

In the vacuum of space,

light travels at a fixed speed
of 186,000 miles per second.

This is accepted as an absolute
truth of the universe.

And that,
says cosmologist Janna Levin,

gives light a unique
relationship to time.

It's actually
completely remarkable

that the speed of light
is an absolute.

It's never faster.
It's never slower.

To understand
the relativity of time,

we really need
to understand light,

and once we start thinking about
the nature of light,

all of our familiar intuitions
are turned on their heads.

If the speed of light
is constant,

then time and space
must shift and distort

depending on your particular
point of view.

Einstein had
this very profound insight

when he started to think about
something as simple as light,

and he realized that if light
was going to be the same

for everybody in the universe

regardless of how fast
they were moving

or where they were
in the universe,

then space and time
had to be different

for different observers.

This means time
is very personal.

It depends on where you are
and how fast you are moving.

And the way you see
your movement through time

may not be the way others
see your movement through time.

Say, for instance,
Janna has a doppelganger

that rides the subways
and taxis of New York.

If Janna's doppelganger
gets in a cab

and that cab travels
at incredible speeds...

...time will flow differently
for each woman.

If she flies past me in a taxi,

it will appear to me
that her time is running slower.

From my doppelganger's point of
view, the street with me on it,

we're flying past her
in the opposite direction,

and as far as she's concerned,
her time is normal.

It's my time
that's running slow.

To understand why this happens,

imagine Janna turns on
a double-sided laser

whose pulsing beams bounce off
the sidewalk below her

and the balcony above her head.

The pulses form a light clock.

Each bounce of the laser beam
is one tick.

Janna sees the light
go straight up and down,

but her cab-riding double
sees something quite different.

From the perspective of the cab,

the light appears to take
a long diagonal

and so seems as though my clock
is taking too long to tick.

So it seems like my time
is running slow.

If Janna's doppelganger
turns on the laser in the taxi,

she will see the beam hitting
the ceiling and floor

right above and below her.

But the Janna on the street
sees the beam move diagonally.

Because the beam has longer to
travel, its tick looks slower.

From my perspective
on the street,

if I'm looking into the taxi,

I see their light
take a long diagonal,

and so I think it's taking
their clock too long to tick.

From my perspective,
their clocks are running slow.

The effect increases
the faster you go.

If the cab approaches
the speed of light,

the speed limit of the universe,

time outside the cab
appears to stand still.

If that taxi was to fly by
at the speed of light,

it would look like my clock
was never going to tick,

like my time had stood still,
like time was frozen.

So, which observer is correct?

The Janna who's standing still?

Or the Janna in motion?

My doppelganger and I
just fundamentally disagree

on the passage of time,

and it's true.

We're both right --
time is relative.

Relativity means that there can
be no single universal time.

However, there was one moment
when all perspectives on time

must have been the same --

a moment when everything existed
in one single place...

The big bang.

One of the hardest things
to grasp about the idea

of the big bang
and the creation of the universe

is the idea that time itself may
have begun in that big event,

that space was created in the
big bang and time began to tick.

Before our big bang, there might
not have been space or time.

Janna believes
the big bang was probably

when all the various time
streams in the universe began

and that, since then,
time has passed differently

in different places depending
on how those places have moved.

But could we create places
in our universe

where time can appear to stop
and then begin again?

If we could hide an event
from light,

could we also hide it from time?

These are questions

Professor Alex Gaeta
asked himself.

A former
competition-tennis player,

Alex is a physicist
at Cornell university

specializing
in ultra-fast optics.

This technology is usually used

for high-speed data
transmission.

But after reading a paper

written by theorists
at imperial college,

he realized it
could also create a gap in time.

You know, light is
an electromagnetic disturbance.

The minute things start
changing,

that's an indication
that time is passing.

So all these changes
that are occurring

are creating all these
electromagnetic disturbances

that we can detect
and measure as passage of time.

What we've figured out
is a way

of essentially
turning off the lights,

turning them back on without,
you know,

you sensing that they've ever
actually been turned off.

What would happen
if you turned off

the light shining on time

long enough to hide an event?

Say, for instance, Alex is in
a close game with his son, Max.

He's coming up to match point,
and he wants to win.

If Alex could create
a hole in time,

no one could see him do this...

To observers, including his son,
Alex wins the set without pause.

Right now, this is impossible.

But all great things
start small.

This is the key component
of Alex's experiment --

the split-time lens.

It focuses light signals
and time

the way a glass lens
focuses light in space.

In a vacuum,
the speed of light is constant,

but that speed changes when
light passes through a material

or when it runs into
another light beam.

Alex's split-time lens
uses both tricks.

Alex shoots a laser
into a beam of light,

slowing it ever so slightly.

The beam then passes through
a glass fiber

where it splits into two parts,

each with
a different wavelength.

The lower wavelength pulls ahead
of the higher wavelength,

leaving a gap
of absolute darkness.

Anything within that gap
is impossible to observe

since there is no light there.

The light then passes through
another time lens

that re-unifies the beam
with no visible change.

Using this device,

Alex has created gaps that last
almost a billionth of a second.

That may not sound like much,

but in the world of high-speed
information transfer,

it's significant.

Let's say you have
a data stream

and you don't want
to interrupt it at all

but you want to put
some information

into that data stream

and then take it out.

So, by creating this gap,

you can create the gap,
not disturb the light stream,

insert a little bit of data,
transmit it,

and then later on,
pull out that data

and then put
the data stream back together.

And that information would be
hidden from the passage of time.

Today, creating a light gap
that lasts for one second

would require
a machine 186,000 miles long.

So Alex will have to win
his tennis matches the hard way.

But the technology
is rapidly evolving.

In principle,
there have been demonstrations

where they can slow
down light by factors

of 10 to the 7th, 10 to the 8th.

In the near future,
it could be even more.

You could essentially
almost stop light,

store light for relatively long
periods of time, seconds,

and then essentially
release it to travel,

again, back at the
speed of light.

Alex and Janna's work explores
the deep connection

between observers, light,
and the passage of time.

It begs the question,

does time exist if there
is no one around to see it?

One scientist says no --

time began
much later than we think.

How often have you woken up
in a darkened room

and had no idea
what time it was?

Have you been out
for minutes or hours?

When you are sleeping, you have
no sense that time is passing.

Perhaps the cosmos experiences
time in the same way.

The big bang was the moment
our universe was born,

but what if it
didn't wake up right away?

Could there have been a time
when the universe had no time?

Professor Larry Schulman
is a little out of place

in dresden, Germany.

His home base is New York's
Clarkson university,

which often sits under
a static sheet of ice.

Not so different, Larry says,

from the state
of the early universe,

when, he claims,
time did not exist.

Larry explores
the behavior of systems

composed of large numbers
of particles

such as the water in
this fountain or the universe.

Statistical mechanics
can also tell us about

the relationship
of light to time.

Light carries information
about events.

We use it to determine
what is happening now.

But because light
has a speed limit,

everything we see
actually took place in the past.

The time it would take,
for example, from the Sun

is about 8 minutes
because it's 93 million miles,

and you figure with a velocity
of 186,000 miles per second,

that's how long
the light would take.

So, if the Sun were to explode,
for example,

you would not know about it

until eight minutes
after the event.

The light of the most
distant parts of the universe

has been traveling toward us
for 13.8 billion years.

This is when the universe began
in the big bang.

The early universe was nothing

but a field
of charged particles,

a dense, hot cloud of plasma.

Photons, particles of light,

could not travel very far
in this soup.

Then about 380,000 years
into the life of the universe,

there was a sudden change
called recombination.

This is when atoms
began to form.

Prior to recombination,

if an electron and a proton

would approach
and bind temporarily,

they would be whacked
by a photon coming along

and be knocked apart.

Recombination is a process

in which the electrons
and the protons,

which were previously loose

and separated from each other
in the plasma,

finally can get together.

It's a bit like hockey.

If you imagine
the hockey puck is a photon.

This is the river elbe,
and sometimes it freezes over.

Supposing I would wait for that

and go out there
with my hockey puck,

I could knock it
to the bank with no problem.

But the universe just after the
big bang was full of obstacles.

Now suppose that surrounding me
were a bunch of goalies

not protecting a goal,

but just making sure that
my hockey puck didn't pass them.

So all these goalies
are standing around,

and every time I hit the puck,
one of them stops it.

This puck
is not gonna get through.

This, Larry says,
is the early universe.

Photon pucks couldn't get past
the electron and proton goalies,

so light didn't flow.

On the other hand, these goalies
are a little bit unusual,

and they alternate boy, girl,
boy, girl,

but at first, they didn't know
that because of their big masks.

After a while, one of them
removes the mask,

and the guy next to her
says, "oh."

Hmm.

Then the puck
can get right through.

Once the photons
could escape easily,

the world
changed dramatically.

In the early universe,
photons could never move freely,

and there was no way
to measure change.

Larry argues,
that means time did not exist.

Only after recombination,

when the universe cooled
and atoms formed,

did light begin
to move around freely.

That, says Larry, is when the
universe's clock began to tick.

The very earliest point,
there's never even a time.

But eventually,
there was something called time,

which was keeping track
of the way things changed.

This could explain the birth
of time in our universe.

But if our universe ends,
will time die with it?

This physicist thinks time
is truly fundamental --

time is always here.

It is space that comes and goes.

Time moves forward,
never backward.

Physicists say that is because
energy always dissipates.

If you wind time back
far enough,

you would see the entire energy
of the universe coming together.

At the big bang, everything
is focused on a single point.

You can't wind time back
any more than this.

Or can you?

Physicist Sean Carroll

of the California institute
of technology

has spent much of his career
contemplating time.

Though the origin of time
is a mystery,

Sean is certain of one thing --

in our universe,
time has a direction,

an arrow
that runs through everything.

Time is a measure of change
in the universe.

If nothing were changing
in the world,

there'd be no way of knowing
that time was passing.

Everything would be the same
at every single moment.

There'd be no clocks.

Time itself would basically
have no meaning.

As long as something is
changing, no matter how small,

time is flowing.

And our universe is in
a constant state of change.

At the dawn of the universe,

an enormous amount of energy was
compressed into a single point.

Then came the big bang.

Since then,
with every passing second,

that energy has become
more and more spread out.

The measure of that spreading
of energy is called entropy.

Sean believes the forward
movement of time, time's arrow,

is the steady movement from
low entropy to high entropy.

But what set time's arrow
in motion?

The puzzle that we have

is that entropy
tends to increase,

but our big bang was a condition
of very, very low entropy,

so how did it get that way?

Where could it have come from?

Everything we know in physics
is things increasing in entropy.

So if you go back
to the big bang,

there was no lower entropy place
it could've come from.

Sean suspects the answer

is that our universe is
the child of another universe.

But what was that universe like?

Maybe like this...

Imagine a universe
that's in equilibrium.

It's in a high-entropy state.
It's emptied out.

It's just sitting there quietly,

much like
the water in this tank.

You don't see any motion.

Now imagine in this universe

where all the energy
is dissipated,

suddenly an area of dense energy
pops into existence,

much like this bag
of effervescent tablets.

The seltzer starts
small and dense and low entropy

just like our universe did near
the big bang,

but then we expanded and cooled,
galaxies formed,

and the arrow of time
progresses from past to future.

Likewise, the seltzer fizzes
and becomes higher entropy

as it mixes
with the water around it.

And eventually,
just like our universe

will come back to equilibrium

and the arrow of time
will cease,

the seltzer reaches equilibrium

by mixing with
the water around it,

and we're back to a state
that doesn't change anymore,

a state without
any arrow of time.

But how could a dead universe,

one with no life, stars,
or solid matter,

give birth to another universe?

According to quantum physics,
even an empty void

will experience tiny
fluctuations of energy.

This means
that every once in a while,

something
can pop out of nothing.

Think about the atomic nucleus
of a radioactive element.

It just sits there.
You look at it.

It's not changing
as you look at it,

but there is a possibility every
second that it will decay,

that it will spit out
a new particle.

What we're saying is that
space-time itself

can be radioactive
just like that nucleus,

except instead of spitting out
a new particle,

it can spit out
an entirely new universe.

New universes may constantly
be popping into existence.

A random quantum fluctuation
in an ancient universe --

a universe so old,
time fell apart --

might even have given birth
to our universe.

This process of starting
with no arrow of time,

budding off a new universe,
having an arrow,

and the arrow only lasts
for a little while

as that universe
expands and cools,

but once it reaches equilibrium,
the arrow stops --

this could happen many, many,
many, many times.

Let's put it that way --

maybe an infinite number
of times,

but certainly
a very, very large number,

so it's possible
that the universe we came from

was nowhere near the first.

Our big bang might
not have been the beginning.

Our cosmos' time could have
ancestors that predated it

and descendents
after this universe is gone.

But there may be
an even deeper truth about time,

a truth we will never learn

until we accept
that it doesn't really exist.

What would we do without time?

How could we keep track
of the events in our lives

without the steady pulse
of minutes, days, and years?

But it may be
that none of that is real.

It may be that time

is nothing more than a mirage.

This is the belief

held by theoretical physicist
Carlo Rovelli.

As a student
in his native Italy,

Carlo was on the barricades,

fighting against
the resurgent fascist movement.

I was young in the '70s,

and there was the big dream
of changing the world.

We failed.
We didn't change the world.

And so I think
I moved into science

because I thought it was another
way of changing the world,

and perhaps I could be
more successful there.

Carlo leaves the centre de
physique theorique de luminy,

a think tank
in the South of France.

But he's still breaking
the rules.

As the leading voice of
the theory of thermal time,

he is raising the banner
for a paradigm shift

in fundamental physics.

In a nutshell,

thermal time proposes
that time does not exist --

at least not at the fundamental
level of reality.

The idea that there's
no time on the fundamental level

is not so complicated after all.

Let me give you an example.

Imagine that you describe
something happening in time,

like this is oscillating
in time.

What do we mean?

We mean that there is something

that moves with respect to time.

But what is time?

Time is the position
of the hand.

So what we
are really observing here,

what we're really doing here
is comparing this movement

with the movement
of the hands of the clock.

So we describe how
the hand's changing time,

but what we really see
is just how this angle

changes with respect
to this angle.

So, do without time means
just to describe the world

in terms of the way
the various variables change

with respect to one another

without ever having to bringing
this unobservable time

into the picture.

Isaac Newton introduced the idea
of a variable, "t" for "time,"

to describe how objects move.

But quantum physics
treats time differently

than Newton's classical system.

In fact, at the planck scale,

the smallest unit
of the physical world,

time variables
simply don't work.

Carlo thinks the only way to
resolve this contradiction

is to go back before Newton
and get rid of the variable "t."

He has completely reformulated
quantum theory

without the use of time.

But that's just the beginning.

The interesting part
is actually the second part

because if we accept the idea

that there's no time
on the fundamental level,

nevertheless
we do experience time.

Time passes for us, right?
We live in time.

So where does
this time experience come from?

The answer,
Carlo thinks, is heat.

When you add heat to matter,

irreversible processes
begin to take place,

events that can't be undone.

Things begin to change in time.

So, every time there is some
lack of reversibility in time,

there's heat.

So time is tied to heat,

and I think that the key idea is
not that heat comes from time,

but is that time
comes from heat.

And heat is thermodynamics,

and we have understood that
thermodynamic is statistics.

So time is tied to statistics.

We don't know
the fine details of nature.

We only understand the average.

We have only
a statistical knowledge.

Say Carlo has an oven.

To measure all the quantum
interactions inside the oven,

he would need to make
billions of measurements.

But no one can do that.

So, instead, he says,

aah!

"This oven is 450 degrees."

Temperature is an average
of the energies

in the countless particles
in a system.

It's what we get
when we give up describing

what's happening
in the quantum world,

and, Carlo says, so is time.

If we could see
all the details of the world,

we would see
a timeless world in some sense.

We wouldn't see this thing
that we feel as time.

To Carlo,

time is just a statement
of limited information.

The fundamental level
of the universe is timeless.

But at larger levels of reality,

when the interactions
of matter and heat

begin to have visible effects,

the thing
we call "time" is born.

Time began when some system,

instead of interacting
just with its neighbor,

interacted with
a big set of systems.

So time began when some system

started having partial
information,

not complete information
about its surrounding.

Time begin with our ignorance
and grows with our ignorance.

It's a radical view
of the universe,

but Carlo has never been afraid
to challenge the status quo.

Is Carlo correct?

Is time really
just our failure to comprehend

the dispersion of heat?

This woman says
there is another possibility.

Time is real.

But it is born and reborn

a trillion, trillion times
a second.

When I move from place to place,

my senses tell me it happens
in one continuous sweep.

But according to quantum
mechanics, any movement...

Is actually a series
of microscopic jitters

through space.

Huh?

No one has yet worked out

how to apply the theory
of quantum mechanics to time,

but some scientists
are getting very close.

If they succeed, we will have to
accept a strange, new idea --

every minute fraction
of a second,

time bursts into existence
over and over.

Like all of us, fay dowker
experiences a flow of time.

She was a girl...

Then a university student...

And now she's a physicist
at London's imperial college.

Nothing is more fundamental
to our experiences

than that we have
those experiences in time.

We are aware of time passing.

Time seems to flow.

We can hardly make sense of our
lives except in the context

of some fixed past of events
that have already happened

and that can never be changed

and some open future of events

that are free
and haven't happened yet

and some mysterious
and elusive moment of now

that appears
to separate the two.

This idea seems obvious.

But, actually, it goes against
our best scientific theory

of how the universe works.

The theory of relativity

tells us space and time
are inextricably joined.

All time that will exist
already exists

in a block we call "space-time."

As we pass from birth to death,

we glimpse
our own individual trails

through this
frozen space-time landscape.

But fay believes the universe
is not a frozen block.

It is a growing pile

made of quantum grains
of space and time.

Space-time seems smooth
and continuous to us,

but that's just because
we're very large

and we see things
at large scales.

So, if we imagine
that a solid cube of something,

say a sugar cube,

represents a piece
of space-time,

then from far away,
that looks solid.

It looks like a chunk.

But we know
that if you zoom in on it

and look at
its more fundamental structure,

we see that it breaks up
into grains.

The idea with a granular model
of space-time is similar.

At fundamental, tiny scales,
it's grainy and particulate.

At large scales, it appears
smooth and continuous.

We don't notice
that granularity.

Just how small
is a grain of space-time?

Inconceivably small.

Roughly a million, trillion,
trillion, trillionth

of a second.

This is what physicists believe

is the smallest possible unit
of measurement.

Fay thinks space-time is built

from a prodigious stack
of these impossibly tiny grains,

which she calls
"space-time atoms."

This marries together
two concepts --

that space-time
is fundamentally atomic

or bitty or granular
at very tiny scales

with the notion of causality,

the fact
that cause must precede effect.

So, for example,
if I hear a loud noise...

...then that will startle me,

and I might drop
my cup of coffee.

So the cause was the loud noise.

The effect was the dropping
of my cup of coffee.

If, as relativity insists,

all of space and time
already exist,

the coffee cup will always fall,
is always falling,

has always fallen.

But in fay's view,

the universe is a set of events
that is forever growing.

When we observe these
connected sequences of events,

what she calls a causal set,

we perceive
that time is passing.

A causal set can grow

by the accumulation
of new space-time atoms.

And this birth
of new space-time atoms

could be the passage
of time as we know it.

What we experience
as the present

is the birth
of these new space-time atoms.

The old atoms don't die.

They pile up into
the thing we call "the past."

The future has yet to be born.

Once a space-time atom
is born and exists,

it will then form part
of the past.

So, in that sense,

it also realizes our sense

that the past is fixed,

that the past has happened,
and that it cannot be changed.

Time may not be
a continuous river,

but rather
an endless rain of events.

So, which concept
of time is correct?

Are we getting closer
to the origin of time?

We may soon know.

In this laboratory, researchers
are working on a new experiment

that could forever change

our understanding of time
and the universe.

Time may have begun
at the big bang.

It may have always been flowing.

Or it could be born
trillions of times every second.

This debate
could go on for decades.

Or it could end any day now.

Because we may
finally have an experiment

that reveals
the true nature of time.

At the Berkeley campus
of the university of California,

Professor Hartmut haeffner
is building a time ring --

an object
that will rotate like this disk.

But while this metal ring

is levitated using
electromagnetic force,

a time ring will be driven
by a jitter in time.

If it works,

this experiment will prove
a controversial theory --

the quantum fluctuations
that have been observed in space

also exist in time.

We physicists like symmetries,

and one symmetry
is like space and time.

We would like to treat them
on the same footing,

so whatever we observe in space,

we think
we should also see in time,

and this would actually simplify
the description of the universe

or make it more elegant.

Nanotechnologist
Tongcang Li, also at Berkeley,

devised the time-ring
experiment.

He approached Hartmut,

an expert in trapping
and studying atomic particles.

But Hartmut had his doubts.

In the beginning,
I mean, I was thinking,

"I mean, they are crazy.

I mean,
this is a ridiculous idea,"

and then we start to talking,
and I realized, "oh, wait.

"This is really weird,
but they are right.

This is the way it should be."

On this electrode,

inside a space the width
of a human hair,

Hartmut and his team will create
a perfectly static landscape --

a landscape isolated
from outside energy.

To further reduce energy
in the system,

he must trap
and cool calcium ions

down to a few billionths of
a degree above absolute zero --

colder than anything
has ever been cooled before.

This will take the ions
down to their ground state --

the state
of minimum possible energy.

Only then can the effects
of space be separated from time.

Imagine these ball
bearings are calcium ions

and we're going to inject 100
of these calcium ions

into our vacuum chamber.

So, at normal temperatures,

these ions move around rapidly
in random directions,

but when we cool them, they form
this ring and they slow down,

and you would expect
that at some point,

this ring stops moving.

It wouldn't rotate,

but if this theory is correct,

that ring should move,
rotate, spin.

An object
at ground state shouldn't move,

because it neither consumes
nor produces energy.

But quantum mechanics tells us
zero does not mean zero.

Even at ground state, there will
still be quantum fluctuations.

In quantum mechanics, there's
always this finite jitter motion

in the ground state.

Things will still move,

but they will move
in an undirected way.

What we are after is something

where there is still motion
in a particular direction.

It would be different
in the sense that it's directed.

Freezing the ions
will allow them

to make only tiny,
random movements in space --

too small to make the ring move.

But if the ion ring
begins to turn anyway,

it will mean there has been
a fluctuation in time.

From the theory perspective,
it's not at all clear

what is going to happen
at these low temperatures.

There are people who say
that this ring should move,

and others say it shouldn't.

If the time ring works,

then both space
and time fluctuate.

That might support fay dowker's
theory that space-time

is constantly generating itself
in quantum dips.

At the very least,
it will demonstrate

that space and time
are inextricably linked

in the quantum realm.

So, we have these
quantum fluctuations in space,

but time we treat as something

which you can know
very precisely.

Well, actually, what I would be
feeling much more happy with

is if quantum mechanics
would also assume

that time is fuzzy,
so to speak,

that you can't tell what time it
is exactly, only approximately,

that you have
fluctuations of time.

And I've never worked
with something

where time fluctuates, so...

When I see it, maybe then it
becomes natural to me, too.

If we find the origins of time,

we will answer one of
the deepest riddles of creation.

But we might also learn

that time is meaningless
to the universe --

time only matters to us

because it anchors us between
our memories of the past...

And the mystery of the future.