Our universe...
Over 13 billion years old,
and full of wonders.
The universe excites,
it enthralls,
it keeps us asking
questions about it.
But how much of
the universe can we see?
There's an entirely
hidden universe out there...
In fact, the vast majority
of the universe...
That isn't made of atoms.
Can we ever truly understand
what the universe is made of?
Even though the laws - of physics as we know
- it should be true - everywhere in the universe,
there are a few places
where these laws break down.
Now, new technology promises
to unlock the secrets
of space itself.
It's incredibly exciting
to use this brand-new tool
we have sent by nature
from the cosmos.
Scientists are hunting
for the invisible matter
that binds
the galaxies together
and investigating
if the universe we live
in is made of alien material
from another universe.
...captions by Vitac...
www.Vitac.com
captions paid for by
discovery communications
Today, across the universe,
astronomers are on a mission
to uncover what
the universe is made of,
- and new discoveries - are revealing
just how little they know.
When somebody asks you,
"how many stars are there
in the entire universe,"
- you have to remember - that we don't know
how large the universe is.
- The universe, for all we know, - could be infinite.
Scientists used to assume
that all things in the universe
were made from countless
tiny particles called atoms...
...from everything on earth
to the brightest star
in the sky.
But is there more to our
reality than meets the eye?
Science can be really strange
because, quite often,
you learn something
new only to find
that you know nothing at all.
Investigators now realize
that our universe
has an immense hidden side.
Even the darkest regions
of empty space teem
with unimaginable wonders.
There's a lot of stuff
in the blackness.
And that blackness is actually
the harbor of great mystery
and great power.
Now, a new generation
of scientists asks,
and how can we find
what we cannot see?"
At Socorro, new Mexico,
this giant telescope scans
the horizon for clues
that might help solve
these mysteries.
Astronomer Sarah Burke-Spolaor
works at the very large array,
a monumental network
of 23 radio antennas.
She hunts for hidden matter,
but not by looking at space.
Sarah listens to
what's out there.
Space is anything
but empty and silent.
Things like stars
make radio noise.
Things like the solar system
and the galaxy make radio noise.
For me, space is
a pretty noisy place.
Sarah investigates if space
contains more than we can see.
Our universe is filled with an
unimaginable amount of matter...
- ...from the rocky planets - like earth
and gas giants like Jupiter
in our own solar system
to the 200 billion stars
scattered across the milky way.
And our galaxy is just
one of two trillion.
There are more stars
in the universe
than grains of sand
on all our planet's beaches.
But could everything we see be
only a fraction
of what is really out there?
If we remove all of
this visible matter,
does anything lie
in the dark void left behind?
The very large array can explore
this space between the galaxies.
It's constantly maintained
and on the move.
Sarah climbs inside
a huge dish.
Each one is a powerful
radio antenna.
Burke-Spolaor:
So, the V.L.A. Does not look
at the stars, per Se,
but it receives radio
emissions from the stars
and from galaxies
and from black holes.
And what that means is that it's
not really a true optical image
like humans would see it,
but we make radio images
of the sky.
Engineers move these dishes
into different positions
using railway tracks.
It allows them to spread
the array over 22 miles.
Sarah uses today's
extended layout to hunt
for a rare type
of radio signal
that could light
up deep space.
Making the array
into a larger configuration
- is a little bit like having - a gigantic camera lens
where we can get a fantastically
good resolution of things
that we see in the sky.
The signal Sarah - looks for
is called a fast radio burst.
They last for just
a few milliseconds
and appear out of nowhere.
The first fast radio bursts
were found in random
surveys of the sky.
- We don't yet know where - they're coming from
or what's even making them.
One theory
is fast radio bursts
come from the corpse of a dead
star in a distant galaxy.
Inside, its core still creates
a magnetic field
1,000 million million times
stronger than the earth's.
This is a Magnetar.
Twists in the magnetic field
tear cracks in the crust
until every few decades,
they trigger a catastrophic
star-quake,
releasing the energy
of a billion quadrillion
atomic bombs
in just a few milliseconds...
A potential fast radio burst.
Over in the control room,
Sarah hopes to use these brief
but powerful signals
to probe the darkness.
The secret lies in what happens
to them on their way to earth.
- So, you can't normally - hear fast radio bursts
- because they happen - at a frequency of about a factor
of 10 higher than humans
can actually hear.
But if you tried to stretch
that frequency to a range
where humans can hear,
it would sound
a little bit like this.
So, what you heard there was
the sound of a fast radio burst
arriving at our telescope.
To us, each radio
burst sounds like a whistle.
But this is a stretched-out
version of the original signal.
Some of the radio waves
that leave the Magnetar
get dispersed and arrive later.
If we had heard it
from its point of origin,
we would've heard
just a blip or a boop.
That would've meant all of its
frequencies are happening
at the same time.
Sarah realizes that
the fast radio burst
has passed through something
on its way to earth.
So, that was a really good one.
You can hear that that burst
came from something
relatively far away
because it went through
so much material
and became dispersed
by that material.
So, what is - the shadowy material
that slows down the radio burst?
The radio beams reveal
that intergalactic space
is filled with vast clouds
of plasma...
...a kind of gas
so hot and diffuse,
it's normally
impossible to see.
Scientists call this plasma
the intergalactic medium.
Sarah plans to use future
fast radio bursts,
like sonar, to find out the size
of these plasma clouds
and how they move
through space.
Burke-Spolaor:
If we know exactly what galaxy a
fast radio burst is coming from,
it can tell us so much
about the intergalactic medium.
It's very much like
unraveling the universe
from here out to the most
distant galaxy.
When I think about
the intergalactic medium,
I like to think about it like
dust once thrown into the air...
So a turbulent medium
that's always moving.
The existence
of plasma reveals
there is no such thing
as empty space.
There is just more matter.
The word "space"
implies something that is empty.
But in fact, the space between
the stars is full of material.
It's just very, very diffuse.
I could take a square meter
of that gas, put my hand in,
and I wouldn't even be able
to feel any temperature
- because there aren't - many atoms there.
Plasma is a gas that's been
heated so much the electrons
get ripped off the atoms,
and now you have a mix of
just these elementary particles
which all have electric
charge flying around.
- We call it the fourth state - of matter, right?
Solid, liquid, gas, plasma.
Plasma is a loose cloud
of broken-up atoms.
On earth, it gives rise
to the famous northern lights.
- But how much of the universe - is made up
of these ordinary particles?
What if I told you
that everything we see,
all of the stars,
all of the galaxies,
was only a tiny percentage
of what's out there?
There's maybe four or five times
as much material that's
in a different form of matter.
It's not made of the same atoms
that we're made of.
We're not really made of
what the universe is made of.
So, what is most
of the universe made of?
Investigators
hunt for an invisible material.
They call it "dark matter."
Our universe is filled
with trillions of galaxies.
But scientists now realize
just how little we know
about what makes up
our universe.
Today, pioneering experiments
probe the existence
of a mysterious second kind
of matter...
Dark matter.
The stuff that matters - to us humans we call "matter."
It's what hits us.
- It's what we stand on, - what we sit on.
It's what we are.
- But then there's - the other stuff
of which there is much
more than normal matter,
and the crazy thing
is that we have no idea
exactly what it is.
Is not just invisible
to the naked eye,
it's beyond human perception.
I love the story about
how humans turn out to be less
and less the center
of the universe.
And in fact, why should
we assume that our senses...
Our sight and touch and smell...
Really tell us everything
that's going on?
We evolved to interact
with regular matter,
things that were made of atoms.
But there's dark matter
right here between my hands,
but I have no way to sense it.
We've been struggling
to understand what dark matter
is for a long time.
The galaxies are spinning
so fast that the outer stars
should be flung off
like water droplets
on a spilling bicycle wheel.
- But they weren't - being flung off,
- so there had to be - something else
out there holding the stars in,
an additional source of gravity
that we weren't seeing.
Therefore, dark matter.
It's a huge mystery.
So why do we think this
hidden universe exists at all?
Deep in the heart
of the English countryside,
a team of investigators
know how to find it.
Professor Mark cropper works
at the Mullard
Space Science Laboratory.
This grand Victorian
country house
hides an extraordinary secret.
It may not appear - from the outside,
but inside this building
we're addressing some
of the most fundamental
questions in science.
Behind the antique facade
lies a labyrinth of rooms,
home to one of Europe's
most ambitious space missions.
Before he can enter, Mark has
to put on protective equipment
to prevent the buildup
of static electricity.
It's harmless to humans,
but devastating to electronics.
Are you almost finished?
- Yes, it is finished, - actually.
- It's actually finished? - Yes.
Wow! Fantastic!
Mark and his team - build and test
one of the most sensitive
cameras in the world.
It will be equipped with 36
image sensors called CCD's.
It's similar to the devices
one has in a phone
or a digital camera,
except this is a rather large
and scientific-grade one.
The camera is destined for
Europe's new space telescope,
a $1 billion project
called Euclid.
The hidden universe
cannot be seen,
but scientists like
Mark believe it exists
because part of it leaves
a dazzling footprint.
The gravity of a galaxy
is so strong
that it can bend light
into a shimmering halo
called an Einstein ring.
This circle is the warped
image of all the stars
in another distant
galaxy behind it.
But there's a mystery.
This is an Einstein ring.
From the position
and size of this arc,
we can reconstruct
how much matter
there would be
in the region of the galaxy.
When we do that calculation,
we find that there
is about four times
as much unseen matter here
than we would expect
simply from the stars
in this galaxy itself.
This galaxy simply doesn't
contain enough ordinary matter
to bend light this much.
This is even more clear
in this other picture
where this blue galaxy
is a much dimmer
and fainter object.
Nevertheless, there's still
a gravitational lensing.
So what's going on?
Most of the distortion
in an Einstein ring
is caused by this
extra matter we can't see.
The mysterious substance
is called "dark matter,"
and it surrounds the galaxy.
This invisible cloud creates
the extreme warping of light,
evidence that dark
matter exists.
We don't know
what the matter is.
It doesn't seem to be made up
of ordinary atoms like the stars
are and like you and I are.
It seems to be something else.
And that's why it's given this
temporary name of "dark matter."
Euclid will hunt for as many
Einstein rings as possible,
but the team's first challenge
is to build a flawless
camera sharp enough
to detect even
the weakest distortions.
Just a single speck of dust
from earth could
ruin these sensors
beyond repair.
So, have you found it - difficult to focus this?
Not that much.
I mean, we've got
a couple of adjustments.
Mark's colleague, Magdalena,
pushes each sensor to its limit.
She fills a test chamber
with liquid nitrogen.
As the temperature plummets
to minus-198 degrees Fahrenheit,
even the pipe freezes.
The team must determine
how each individual sensor
will perform when in space.
Mark wants to measure
how every galaxy bends light
to calculate exactly
how much extra matter
and energy exists
in the universe.
It's been a very significant
realization to understand
that we know so little about
what makes up
most of the universe.
I'm sure that Euclid will be
absolutely profound
in changing physics
at a very fundamental level.
One of the great mysteries
that's been with us
for actually several decades
is dark matter.
- And one of the questions - about it is, "well, what is it?"
And we actually don't know.
Dark matter does not
reflect or absorb light.
So far, scientists can
only detect its gravity.
The best-bet hypothesis is that
it consists of W.I.M.P.S...
What we call weakly interacting
massive particles.
- They're little - fundamental particles
left over from the big bang,
and we haven't directly
detected them yet
because they don't interact
with detectors very well.
But hidden within the Gran Sasso
mountains of central Italy,
this research scientist
has made it his mission
to find a dark matter particle.
Hidden inside this mountain
is a machine designed to detect
the most elusive particles
in existence.
To get there, he must travel
a mile into the bedrock
through a labyrinth
of tunnels and chambers.
Nuclear physicist
Marcello Messina is on his way
to a towering
dark matter detector
called xenon1t.
This experiment took
almost two years to build.
- At the top and bottom - of the tank
are light-sensitive detectors.
Inside is purified water
and 135 pounds of xenon,
a rare gas in liquid form.
The mountain poses
no barrier for dark matter.
Cosmologists believe that
a halo of dark matter
surrounds our galaxy
like a giant invisible cocoon.
But inside, it moves
in eerie streams.
The flow of dark matter
is bent towards
a planet's gravitational core,
forming dense trails.
Particles of dark matter
should be passing effortlessly
through the earth
every second.
But if that's true,
can we ever detect them?
Marcello
thinks he's found a way.
He's looking for the footprint
of a single dark matter
particle passing
through the earth.
He hopes that inside the tank,
one or two might collide
with atoms of xenon
and generate tiny
flashes of light.
That's easier
said than done.
Natural radiation can also
create flickers of light,
so the xenon needs
to be shielded
and kept free
from contamination.
- But even the edge - of the container
could interact with pure xenon,
so the team only
looks for flashes
at the very center
of the liquid gas.
Marcello knows that the odds
of ever seeing
a true dark matter collision
are incredibly low.
The more scientists come
to grips with dark matter,
the more they realize
just how little they know
about the structure
of the universe.
But dark matter and our matter
do have one thing in common...
Gravity.
So, the key thing
about dark matter...
- And it's the reason - we know it's there...
Is because it has a very
strong gravitational signature.
So could gravity explain dark
matter's role in the universe?
- The universe that - we live in today
was designed and sculpted
by dark matter,
and that dark matter was moving
under the influence of gravity.
Scientists try to find out
if dark matter shapes our cosmos
by exploring what the universe
would look like without it.
The hunt is on for
an invisible material
called "dark matter."
It cannot be seen or touched.
Astronomers can only detect
dark matter's footprint
by the way its gravity
bends light.
We think there's dark matter
because things don't
add up without it.
We can look at galaxies,
clusters of galaxies,
and see that actually
they're not behaving
in the correct way.
But no one has ever
seen a dark matter particle.
- So what role - does dark matter play
in the structure
of the universe?
And what would the cosmos
look like without it?
Astronomers explore
what the universe
is made of by playing god
with the laws of physics.
Dr. Richard Massey creates
virtual galaxies
inside a supercomputer.
What we do here in Durham
is we use supercomputers
like this to run simulations.
And we keep going and tweaking
the laws of physics
until we produce a universe
that looks just like our own.
- And that's the way - that we figure out
exactly how the universe works.
Astronomers think
that dark matter's gravity
does more than just bend light.
It binds and links
the galaxies together.
It lures intergalactic plasma
into long streams,
laying the paths
along which galaxies formed.
It spreads out like
a web across the cosmos.
Our whole universe
could be sitting
on a skeleton of dark matter.
Richard investigates what would
happen to the cosmos
if we could tweak
dark matter's gravity.
His team will simulate
a real collision
between two groups of galaxies.
- So, how do we want - to re-normalize it
to change the overall...
It took place over hundreds
of millions of years
in a corner of the cosmos
called the bullet cluster.
Gravitational lensing
distortions predict huge amounts
of dark matter.
Richard's team programs
a supercomputer called Cosma
- to simulate two - different versions
of this cataclysmic phenomenon.
Nature does this kind of
experiment for us all the time,
- and if we watch - those collisions and see
- where the bits - of dark matter go,
we can figure out
what this dark matter is.
Richard models
the first simulation
around the real collision.
In pink smash into each other.
But the dark matter
in blue passes
through everything,
even itself.
The dark matter just doesn't
care about the world around it.
It passes straight
through the collision.
- It ends up further away - from the point of impact
than the ordinary stuff.
On the face of it, dark matter
doesn't appear to play
any role in the collision.
But Cosma now runs a second
simulation without dark matter.
Here we've run - a simulation in which
there's no dark matter at all,
and it looks nothing
like the real universe.
When these two lumps
of ordinary materials...
Stuff that we're made from...
- When they collide into - each other, they slow down.
And it really is a giant
cosmic car crash.
In the second simulation,
everything slows down
and explodes around
the point of impact.
In fact, the big lump
of galaxies
is completely destroyed.
- All the galaxies end up - flying out of the way
- because there's not - the dark matter
there to hold them together.
A universe like this wouldn't
have ever been habitable.
Dark matter is the glue
its gravity pulls ordinary
material into an endless web.
The analogy I have is that
when you're flying
over a mountain range,
the snowcapped peaks are like
the visible matter...
The galaxies that we see...
But underneath it is a huge
backbone of dark matter.
And surprisingly, this
dark matter web is expanding.
When we look at the universe,
we can see that the gaps
between galaxies
are getting bigger.
Something is stretching
space itself.
We believe that there
is an energy
that suffuses space uniformly,
invisible because it doesn't
give off light, and moreover...
And this is the kicker...
This energy gives rise
to a repulsive
gravitational push.
Cosmologists
call this new invisible
substance "dark energy,"
but they have no idea
how it's able to stretch space.
Space has a sort of
springiness or elasticity.
So how does this manifest
itself to become dark energy?
That's the question,
'cause we don't understand space
at a very fundamental level.
So what is dark energy?
The summit of Kitt peak mountain
in Arizona provides
a ringside view
of the cosmos.
Astronomer Arjun Dey searches
for a pattern in the stars
that might unlock the secrets
of the mysterious dark energy.
Well, I've always been
fascinated by astronomy from
when I was a child.
- So when I was in - about ninth grade,
we built a telescope,
and I used it
to look at the stars.
Arjun thinks - he can measure
how fast the universe
is growing.
Understanding dark energy
could be his first step.
We think dark energy first began
to be a significant
component of the universe
about 8 or 10 billion years ago,
and it's been growing
in its impact since.
Around 2000, we have essentially
realized that the universe
is not just expanding.
The expansion is accelerating.
And in fact, we now think
that most of the material
in the universe is stuff
that we don't understand at all.
Arjun works with a team
to re-configure
Kitt peak's telescope,
one of the largest
in the world.
It's beautiful, isn't it?
They will use these
telescope to hunt for a faint
but distinctive pattern
in the stars
laid down during
the early universe.
Billions of years ago,
the cosmos was just
an ocean of hot, dense plasma,
but slight fluctuations caused
some regions to clump together.
Inside, as they grew larger,
heat built up until they could
no longer contain
their own pressure.
Pressure waves rippled out.
The waves created identical
rings of dense plasma,
each one 450 million
light-years across.
Galaxies formed around
these rings,
leaving a distinctive pattern
that's frozen in time
and still with us today.
Because Arjun knows the
exact size of each ring,
he can use geometry to work out
how space has stretched
over time.
A telescope is effectively - a time machine.
Light that leaves galaxies
takes a certain finite amount
of time to reach us.
For example, the largest nearby
galaxy is the Andromeda galaxy,
which lies about
2.2 million light-years away,
and that means that the light
that we detect on earth
has left that galaxy
2.2 million years ago.
Inside the camera,
tiny optical fibers
will capture the light
from 5,000 galaxies at a time.
So, currently what we have
in here is a prototype
for the camera
that we'll be building
for our cartography experiment.
This camera is called ProtoDESI.
It has three
fiber-positioning robots
that allow us
to position fibers on galaxies
to an accuracy of about
5,000ths of a millimeter.
And we're testing to see
how well we can do that.
The finished camera
will allow the team to map
a third of the entire sky
to see how quickly the galaxies
are moving away from us
and explore the impact
of dark energy.
Well, we're at the beginning
of an amazing adventure.
We're building one of the best
mapping tools we've ever had
to make this kind
of exploration of the universe.
Who knows what
we'll find, right?
To give you an idea,
let's think about a cappuccino.
So, at the very very heart
of what you're doing,
there's this coffee underneath,
and that's the dark energy.
That's where most of the energy
of the universe is contained.
And then there's
a froth of milk on top.
Well, that's pretty substantial.
That's really what
dark matter would be.
- And then what would - regular matter be
in this cappuccino universe?
How 'bout a couple
sprinklings of chocolate on top?
The universe appears
to be very finely balanced.
Without all the hidden dark
matter and dark energy,
its structure
would fall apart.
But there's a final mystery...
Cosmologists have no idea why
the universe is made this way.
We're gonna have to explain
why it is that dark matter
is whatever, 23%, 24%
the mass of the universe,
why dark energy is 70%.
And if anybody cracks
those challenges,
I think many of us view
that we will really leapfrog
to the next level
of understanding.
The answers could lie
beyond our universe.
There are possibilities
being explored that either
or both dark matter
and dark energy
might actually come
from another universe.
Could most of our universe
really be made from material
that's coming from another?
It sounds like science fiction,
but the proof might be
clearer than we think.
The universe
is getting bigger.
A mysterious substance
called dark energy
is growing in strength,
driving apart the web
of galaxies held together
by dark matter.
So, instead of having energy
that brings things together,
like normal matter has,
this dark energy stuff
- has a gravity - that is repulsive,
that pushes things apart.
So at a certain point,
the outward push of dark energy
became greater than the inward
pull of normal gravity,
- and instead of - the universe expansion
slowing down with time,
it began to speed up with time.
The eternal battle between
dark matter and dark energy
is so puzzling
that some ask,
"are both of them really part
of our universe at all?"
Well, people have certainly
suggested that dark matter
- might come - from another universe
because if you think
about it, dark matter
is some source of gravity
that we don't see.
Maybe we don't see it not
because it's dark, per Se,
maybe we don't see it because
it's in a parallel universe
- in which light - from that universe
can't reach us
but gravity can.
It's possible that - the dark energy
actually comes from
outside our universe.
In fact, maybe the accelerating
expansion of our universe
is actually caused
by other universes
surrounding ours
pulling outward on it,
so to speak.
When I was a kid, the joke was,
define universe
and give three examples.
It was a joke because the
universe is all that there is.
Well, now it's not such a joke.
So, could most of
our universe be made
from the material of another?
If we could step
outside our universe,
some scientists believe
it could be represented
as a flat sheet.
Beyond it, a sea of
alternative universes
could be leaking dark energy,
which seeps out of one sheet
and flows into ours.
Our increasing dark energy
could be the runoff
from other dimensions.
But is this theory
science fiction?
At a small town
in West Virginia,
radio astronomer David Frayer
tests this extraordinary theory.
Green bank is the perfect place
to look for other universes.
It's in a parallel dimension
of its own, where mobile phone
and Wi-Fi signals disappear.
- -Hey, Sherri. - -Hey, Dave, how are you today?
- Pretty good. - How's that creek going?
- Oh, it was rough - this morning.
It was overflowing?
- Yeah. - Have a good day.
- You, too, have a good one. - Tell everybody hello.
Will do.
All radio emissions - in this town are strictly
controlled so astronomers
of the nearby observatory
can work in total radio silence.
If you had a cellphone on Mars,
and the telescope
was looking at Mars,
we could easily
see that cellphone on Mars.
In fact, it'd be
a million times stronger...
- The signal that we'd get - from that cellphone on Mars...
Than the typical signals
that we're trying to see
out in deep space.
Green bank is home
to the largest moving radio
telescope in the world.
This giant antenna listens
for the weird
and wonderful sounds
of deep space,
including very faint signals
from the dawn of time.
David steers the telescope
from the main control room.
This nerve center is encased
in a metal box.
The idea there is to keep
all the radio emissions
from the computers and all the
other electronic equipment
inside this metal box
- so it doesn't interfere - with the telescope
that's sitting a mile away.
David links up
with professor Ranga Ram Chary
at Caltech in California.
- Hey, there, Dave, - how's it going?
Pretty good.
We did these tests to see
if we could observe
in a different mode...
Ranga wants green bank - to investigate
microwaves left over
from the early universe.
This ancient radiation
still leaves a faint glow
in the night sky,
but Ranga thinks
that inside it he's spotted
the imprint of another universe.
If we can imagine
our universe as a bubble...
- ...it could float - amongst other bubbles
within what scientists call,
"the multiverse."
As a big bang creates
a new bubble universe,
it inflates rapidly
and could collide with another,
leaving a bruise
of alien matter...
...an impossibly bright
spot of hydrogen
caused by two universes
overlapping for
a brief moment in time.
Confirmation of this intense
hydrogen signal would prove
that matter in one universe
could have an effect on another.
So, in terms of this excess
hydrogen that we're seeing,
we think it's our universe
has expanded
into and is colliding
with another universe.
This is why this study
is so interesting,
because it's the first
observational test to understand
whether or not there may be
other universes out there.
And if that's the case,
that tells us a lot
about what
the underlying structure
of our universe
and other universes are.
David will try - to confirm
this mysterious
hydrogen emission.
But first, he investigates
a way to boost
the sensitivity of the telescope
- because the original signal - is so old,
it's incredibly faint.
This is K.A.-Band receiver that
works in the wavelength range
that will be able
to see the hydrogen
from the early universe.
The temperature
of the cosmos is very cold,
roughly minus-450
degrees Fahrenheit.
If this receiver is cold, too,
it should detect much more.
The important stuff
is a low-noise amplifier
that's within this cryostat
that's kept at 15 degrees
about absolute zero.
It's a hugely
ambitious experiment,
but it might reveal
what makes reality.
We could potentially just be
one universe among many,
many universes.
I mean, we used to
only think our sun
was the only special star,
- and now we know - there are billions
- and billions of stars - in our galaxy.
It would change our reference
frame of who we are.
There are many, many ways
in which there
could be a multiverse.
I actually think
that it's quite likely
that there's a multiverse,
but I can't prove it.
If we were to go - that next step and the universe
is just one of many populating
an even larger landscape,
wow, we'd be knocked
so fully off the central throne
- that I think - our whole perspective
of what reality is would change.
Our universe may be
made from the multiverse.
Dark matter and dark energy
could be the effects
of another universe
that we feel in our own.
The existence of an infinite
number of universes
might even explain
why we exist at all.
Why is it that conditions
in our universe seem to be set
to just the right values
to allow galaxies and planets
and people to exist?
And it is a puzzling question.
And one potential answer is
maybe there are many universes,
each with a different value
for things,
and one special universe
where the values
just randomly happen
to have the values
that we see here.
The conditions are right
for our form of life,
and, of course, that's where
we would find ourselves.
So, can we ever truly - know the answer
to the ultimate question...
What is the universe made of?
My best guess is that there
is no end to stuff to find out.
I actually am not one of
the people who believes
that we'll find a theory
- of everything, - and then we're done.
- We will go to the beach - or what have you.
There will just be
more big questions.
And that's what
makes it exciting.
Wouldn't it be - depressing to be in a universe
where you could
understand everything?
I mean, I don't like that idea.
I love it that there
are still real
mysteries out there.
As tremendously successful
as our physics
- is right now - at making predictions
- and explaining - the world around us,
we know it's not the end.
We know there's going to be
a next best way
to describe the universe.
I like that open-endedness.
I love that about the universe.