We all have questions.
Big questions.
Did the universe have a beginning?
It's part of what it means to be human.
Where was the big bang?
And it's just mind-blowing.
My name is Stephen Hawking,
and I believe that anyone can answer big questions
for themselves.
So with the help of some ordinary people...
Paul, you're not even close.
I'm sorry. Heh heh.
And a team of experts...
We could understand the origin of everything.
We are going on the ultimate voyage,
a quest to answer the greatest mysteries
of the universe...
Huh.
Using the power of the human mind.
Brilliant!
Because anyone can think
like a genius.
"Genius by Stephen Hawking"
was made possible in part by
contributions to your pbs station from viewers like you.
Thank you.
Where did the universe come from?
Have you ever looked up at the night sky
and wondered where it all came from?
It is hard to think of a bigger question.
The answer, as most people can tell you,
is the big bang.
Everything in existence
expanding exponentially in every direction
from an infinitely small, infinitely hot,
and infinitely dense point...
Creating a cosmos filled with energy and matter.
But what does that really mean
and where did it all begin?
I think that with a little help anyone can work it out,
so let's see if I'm right.
I have asked 3 curious minds
to join me on a journey of discovery.
A series of fun challenges awaits them.
They will be given tools and equipment.
Can they follow the greatest thinkers in history
and discover the origin of the universe?
Wow!
What a question. Ha ha ha!
Where do you even start with that?
I think the universe began in space at some point.
I think it's called the big bang
because it was a bang and it was big.
It's something that's almost impossible
to get your head around.
My volunteers' first challenge
is to grasp the enormity of the universe
by calculating the total number of galaxies
visible from earth.
So I've brought them somewhere with plenty of space
and given them this image.
It looks like, uh, stars.
A picture of the universe.
Yeah. All right.
There appears to be stars,
but clearly underneath, it says, "10,000 galaxies."
Look at all the different shapes and colors.
I know.
Every speck of light here...
Is a separate galaxy.
It surprised me that 10,000 of anything
could fit in a square foot, let alone pictures of galaxies.
It's a beautiful picture.
Clearly, it's a scientific picture.
It's a view that you would never see with your own eyes.
The photo is a famous one called
the ultra-deep field image.
It's a part of the night sky like any other,
taken by the Hubble space telescope.
It reveals nearly 10,000 galaxies,
some over 13 billion light years away,
yet because this image covers only a fraction of the sky,
it shows just a small number of the galaxies out there.
To somehow come up with a number
of how many galaxies there are in our universe,
that we can see, uh, where to start...
Where to start with that one?
Let's assume this is planet earth... Right.
And then we just have to see
how many of these tiles we need
to cover the whole... Right.
And obviously, this is just one point,
but the sky... Or space, universe
is all around the sphere.
We started coming up with ideas,
and we said, "ok. Hold on."
"This is just a piece of the sky.
Could we just replicate this picture?"
My volunteers have figured out
they need to imagine the night sky as a sphere
surrounding our planet.
If they can work out how many patches of sky
the size of their Hubble image it would take
to cover this sphere,
then they will be able to calculate
how many galaxies there are visible from earth.
The scale was... was clearly
the, um... the crux of this matter.
We had to figure out how much of the sky
that picture covered.
How many are we gonna need...
To cover the whole... to cover the entire sky
and of course what's below our feet?
From here,
we're gonna talk about, I don't know, what, 600?
Yeah. And that's at our arms' length.
Imagine... imagine I'm all the way back here.
Yeah. It just grows exponentially.
Now how many is it? Yeah.
It quickly became evident
that we needed some reference points here.
We couldn't just guess as to how far away we needed to be.
Excellent.
I have given them the crucial piece
of equipment they'll need.
Ooh! Telescope. Oh, wow. Ok.
Nice! Oh, wow.
This telescope represents
the Hubble space telescope.
It sees exactly the same amount of sky,
so if my volunteers can precisely fit the image
I've given them into the telescope's field of view,
that will help them work out how much of the sky it covers.
We could take this image away from the telescope
until it fills the viewfinder,
and then we'll measure the distance
between the image and the telescope
that actually made the image.
Yeah, yeah.
How far away will they need to take the image?
You ready? Yeah.
Ok. Let's do it.
Will 300 feet be far enough?
Paul, you're not even close. I'm sorry.
Ha ha ha!
Ok. We'll keep going back.
You're looking so small.
This time, they're trying 600 feet.
Ok, Marcia. How we doing?
Do we need to go further?
Yeah, a lot further. Sorry, Paul.
That's ok. I'll keep going.
Let's go.
Well, I've just started thinking about how little
area of sky we've got here on this thing.
My volunteers aren't the first to underestimate
the size of the universe.
In the early 20th century, people really didn't know
what was beyond our galaxy.
They knew there were lots of stars in the sky,
but for all they knew, there was one galaxy,
uh, which we lived in, and beyond there,
there was just nothing.
Then came revolutionary mind Edwin Hubble.
He used the world's most power telescope
on top of mount Wilson to study smudges of light
called nebulae,
thought to be just gas and dust.
What he saw changed everything.
It took the construction of mount Wilson in 1926
to show that the nebulae, these little clouds of gas
that they'd seen, were actually full of stars.
And so from that point on, it was clear
that the universe was full of galaxies.
The discovery suddenly changed
our picture of the universe completely.
Almost a century later, the space telescope
that bears Hubble's name
gives us our most up-to-date estimate
of the number of observable galaxies in the universe...
Which is what my volunteers are trying to work out
on their own.
Oh! Someone's legs.
Probably my legs.
I'm starting to come down.
Yes!
Oh! I see white board.
Hey, hey!
Ok. Now if you can move it to the right now.
Perfect.
Yeah! We got it!
Ha ha ha!
Hey, hey!
Now they have framed their Hubble image
within their telescope's viewfinder,
they're ready to measure the distance back
to the telescope.
So that distance is crucial
because that distance will then give us
that radius that we need in order to calculate
just how many images we would need
to fill the whole sphere, if you like.
Ok, Marcia. We've got our distance,
so, um, we're gonna start measuring back to you now.
Excellent.
Looking back at the telescope,
it's truly astonishing at how small it must look
from her end
and how small a piece of sky
we have a photograph of.
It was surprising to see how far we had to walk
before the image came in view.
Oh, wow. Excellent.
We made it.
What have we got then?
Ok. So the terrain wasn't completely flat,
and we just got over 1,000 feet distance,
so I think for the purpose of the exercises,
would you agree to round it to 1,000 feet?
Ok. 1,000. Yeah.
I think I am, as well.
Ok. Ok.
My volunteers will need to use
the formula for calculating the surface area of a sphere.
They have measured the radius,
the distance from the telescope to the image.
Now they'll need to square it,
multiply it by 4,
and then by pi, 3.14.
So we have the 1,000-feet radius.
Right. Squared.
Multiply that by pi and times 4. That's...
12 million...
560,000.
Square feet.
That's the answer,
and this image is one square foot,
so now they can work out the number of galaxies
we can see in our universe.
And this tile is one square foot.
Ok. So what that is saying is
we will need 12,560,000 of these ones
to cover... to tile the whole sky.
To tile the whole sky.
And each one of those has 10,000 galaxies,
so if we got that 12,560,000 times 10,000,
that should give us the number of galaxies.
125,600,000,000 galaxies.
Ha ha ha! Wow!
By using a detailed image from the Hubble telescope
and a little mathematics, my volunteers have estimated
the astonishing number of galaxies
that scientists have observed in our universe.
With more advanced telescopes, we may one day be able
to see 200 billion galaxies out there.
It's just mind-blowing because this isn't planets,
this isn't stars.
This is galaxies within our universe.
It made me feel so small and insignificant,
completely insignificant.
My budding geniuses have so far grasped
the remarkable scale of our universe,
but can they take the next step
and begin to figure out where I all came from?
The search for where the universe began
is a relatively recent quest.
Until 1929, Edwin Hubble, Albert Einstein,
and many other great minds had a fixed view
of what the universe was like.
Einstein had himself published a paper
according to which the universe was static.
Einstein thought philosophically that the universe
has always been here, will always be here,
is unchanging, and he thought that was
a sensible philosophical picture.
But then in 1929, Hubble discovered something
that changed everything.
I want to see if the volunteers can understand
what Hubble found...
So they've come here...
To a quarter-mile drag strip...
And a very special vehicle.
Oh, my goodness! It's a bug!
Yeah, yeah. It's a beetle.
It's a bug!
A really fast-looking bug.
It's unlike anything I've ever seen.
It's electric.
This is the world's quickest accelerating
electric drag racer...
Fast but very quiet,
an advantage for what I have in store.
So what's this?
Looks like a s... like a siren or something.
It is a siren I think.
What's this for?
Ooh! Ha ha ha!
That's cool.
There is challenge to use the sound
of this siren to determine the speed and direction
of the car.
Oh, no. Ha ha ha!
I have also given them a laptop and microphone
to record the siren's sound waves.
What do... what do you think we're doing here, ok?
Yester... Ha ha ha!
So what...
Will they work out how?
We've got sound.
Sound is important.
So sound gives you a hint.
They seem to be on to something,
but there's only one way to find out.
Immediately, I'm thinking,
"oh, we're all going to end up racing."
Whew.
Let's burn some rubber.
Oh, wow.
Ha ha ha!
And off he goes.
Ha ha ha!
Whoo hoo hoo hoo!
That thing flies.
Ha ha ha! It was halfway down the track
by the time I turned my head.
Ha ha ha!
Oh, there he is. There he is.
Ha ha ha!
How was it?
It was amazing.
Well done. Oh, my goodness.
We got... we got some interesting data here, as well.
Is that my siren?
That's the siren, so right around here
is where you started,
and then you're moving away from us,
moving away from us, moving away from us, moving away from us.
We observed the sound waves
moving by a shift in tone.
There is clearly a change
in the frequency,
and that started giving us an idea.
Ok. We can use the waves of sound to determinate, um, direction.
And we figured out
that we were probably going to be doing something
with the Doppler effect.
My volunteers have grasped a critical concept,
an effect named after the 19th century Austrian physicist
who first proposed it... Christian Doppler.
It's all about the way waves travel
from a moving object.
Sound throws off a regular pattern of waves.
As the source moves, each successive wave
is reduced closer to the observer,
who hears the increased frequency
as a higher pitched sound.
After the sound passes, the wave frequency decreases,
and the observer hears a lower pitched sound.
Can my volunteers figure out how this principle helped
scientists discover where the universe came from?
I think we should try
the second run repositioning the microphone.
My volunteers realized there's a better place
to experience the Doppler effect in full.
Fast in this direction.
We're gonna put the microphone halfway through the track
and see what happens.
Cool. Let's do it.
Marcia's gonna go in the car.
I'm really excited about... heh heh...
What's gonna go down.
From halfway down the track,
they can record data of both the car
coming towards them and going away from them
without so much interference from screeching tires.
Ok. We... we recording?
Yeah. Recording. Yeah. Everything's good.
Ok, Marcia. We're ready when... whenever you are.
I'm strapped up, and everything's really, really tight...
And then all of a sudden...
Ha ha ha!
You got it?
I got it. Excellent.
That was really fast.
As the siren on top of the car approaches the microphone,
the tone is slightly higher,
and then as it moves away from the microphone,
it gets slightly lower.
It's like vrrroooommm!
Kind of just the sound changes.
Marcia, are you all right?
I start cursing because I'm moving,
and my body... ha ha ha...
My body is... is still at the starting line.
It was exhilarating.
My volunteers have heard
the full Doppler effect connection
and the made the link between the pitch of sound
they hear in their vehicle's direction
relative to them.
Hello. Hey, Marcia.
Hi. How was that?
Oh, my god. How was it?
We can see what my trackside volunteers experienced.
They recorded a high-pitched sound
as the dragster approached because the sound waves
reached them with a higher frequency.
The change to a low-pitched sound
was because they experienced waves a lower frequency
as the dragster sped away.
Ha ha ha!
I mean, we certainly heard it.
As you came toward us, you were like, "nnnrrrr!"
It just goes, like...
That drop in sound.
Now using special audio software
which measures the drop in frequency
as the dragster races by,
my volunteers can calculate the speed of their vehicle.
A breathtaking 138 miles an hour
reached in just under 10 seconds.
I didn't actually think that a bug could go so fast.
Very, very fast. I didn't expect the car
to move that... that fast.
Will my volunteers be able to figure out
the connection between the Doppler effect
and what scientists have observed in our universe?
In 1929, scientists discovered something
that turned the accepted model of the universe on its head.
Edwin Hubble found that almost all the galaxies
beyond our milky way are moving away from us.
The universe must be expanding.
So how did Hubble go about detecting
the speed and direction of galaxies
billions of light years away.
That's what the volunteers are trying to understand.
Initially, I thought we're measuring sound,
but, you know, galaxies don't make a sound.
So clearly, were not gonna be using sound
to listen to the sound coming from galaxies,
but, um, sound is a wave,
um, just like light travels in waves, as well,
so when the source is moving,
it changes the frequency.
It widens the frequency as it's moving away.
So when it comes to galaxies, we don't look for sound,
but we kind of measure the waves of the light.
That's right.
So will my volunteers grasp the beautifully simple way
to detect a change in the frequency of light?
We sort of figured out that when we get a rainbow
light hits water and it splits into different colors.
We also get different frequencies,
and color and frequency are linked when it comes to light,
so we're sort of wondering whether perhaps
the... the color of galaxies might give us a clue
as to which way they're moving...
Towards us or away from us,
and maybe that's the way that we can measure
which direction galaxies are moving,
by studying the color of the light from them.
They've got it.
High-frequency light appears blue.
Low-frequency light appears red.
My volunteers have realized the speed and direction
a galaxy is traveling can be deduced simply
by observing its color...
And in 1929, that's precisely how
Edwin Hubble observed galaxies were moving away from us.
Hubble was looking at the most distant objects he could find.
That's what you do with the biggest telescope you have.
If you see a star like the sun
and you put it at a much greater distance,
obviously it would appear much dimmer,
and so he uses that fact to tell him
the distance of the galaxies.
What he notices is that the galaxies which are dimmer
and therefore further away are redder,
and the interpretation of this reddening
is something called the Doppler shift,
which is that if something is moving away from you
the light we receive is shifted into the red.
It was a very radical idea that the universe was expanding
because if you took it seriously,
it implied there was a beginning...
That you could extrapolate the expansion backwards in time,
and it would have implied that everything in the universe
emerged from what we now call a singularity.
With Hubble's discovery, it became clear
very dramatically that potentially
we could understand the origin of everything.
Hubble's discovery was recognized
as very important at the time,
but the notion that we could actually understand the big bang
at that time seemed a step too far.
You know, how would we ever answer questions
that grandiose?
If scientists were to believe that
the big bang theory solved the problem
of where the universe came from,
they'd need evidence it happened
precisely as the theory described.
Scientists predicted the big bang's
initial burst of light from just after the big bang
would be detectable today as microwave radiation.
The race was on to find it...
And the first lead came from an unlikely source,
American radio astronomers Arno Penzias and Robert Wilson.
Penzias and Wilson were interested
in studying our galaxy.
They were using new technology, new radio telescopes
to look at radio waves,
but wherever they looked in the sky
and however they tuned their telescope,
they kept picking up this very faint signal of light.
Now for a while, they were convinced
that it must be something that was getting
into the telescope that wasn't real,
that was either some problem with their telescope itself
or something inside the telescope itself,
but there was no explanation for this faint light
that appeared to be coming from space
and everywhere in space,
and quite quickly, it became completely obvious
that what Penzias and Wilson were seeing with their dish
pointing at different parts of the sky
was exactly this big bang signal.
It was a historic moment.
We saw almost back to the big bang itself,
and scientists had the evidence they had been searching for.
So this signal was hugely important
for convincing people that the big bang had happened,
and so quite quickly, people who hadn't
previously been convinced by the big bang,
their minds were changed.
But we don't have to take their word for it.
What's remarkable is the echo of the big bang
is something we can all listen to.
So one of the remarkable things
about the cosmic microwave background radiation is
you can actually pick it up and hear it with a radio.
This light is hitting us all the time,
and its wavelength is the right kind of wavelength
that a radio can actually turn it into a signal
you can hear,
and when you turn between channels
on an old-fashioned analogue radio,
you can hear that hiss,
that little fuzzy noise that comes
between radio stations.
It is actually light from the big bang,
and you can actually hear it on a radio,
and that's extraordinary.
But this is only part of the story.
What's crucial to understanding the beginning of everything
is not simply that the universe is expanding
but the unexpected way in which it does expand
because Edwin Hubble's data from his observation
of moving galaxies contains a further secret,
one that I hope my volunteers will grasp
in their next challenge.
To see if my volunteers can work out
where the universe came from,
I have brought them somewhere they can exercise
more than just their minds.
Track and field. Very cool.
Indoor arena. Ok.
We're in an indoor running track.
What's this got to do with the universe?
Morning, guys, morning.
All right. Right.
So we have some signs.
My volunteers have the equipment they need
to organize a special race...
Safety pins. Safety pins.
Mimicking the movement of galaxies in space.
Will they figure it out?
Oh, so these are different galaxies
and their, uh, distance from earth.
Oh, wait. Guys, look.
They have, like, little galaxies on them.
Oh, they do.
Look at that. Ha ha ha!
This is perfect.
I noticed that all of the t-shirts
have galaxies on them, so I'm assuming that
each of these runners will represent a galaxy.
You know what these look like to me?
These look like race numbers.
Race numbers.
Each of the race bibs contains
name of the galaxy and how far the galaxy is in light years
away from earth.
I think we just put these on
our lovely volunteers. Ok.
And then we can have a race.
Sounds like a good idea. Yep.
Let's have a race. Let's have a race.
To help them uncover the secret in Hubble's data,
my volunteers will need to set up
the starting point of their race carefully.
All right. So we got all our galaxies.
Yeah.
We have to do everything to scale, right?
First of all, we have to establish our earth.
Which is gonna be our start line.
These starting blocks are not in line.
They're all at different distances
from our starting point.
Because the distances they have
is light years from earth.
So I'm thinking we need to... we need to
get these guys in the right order.
In order. Ok.
The cogs start turning. "Hang on a minute.
"Perhaps we need to be matching up these numbers
with the starting positions for these runners."
Good work.
They're correctly replicating the layout of our universe
as we see it from planet earth.
She's right here.
Then it's 210 billion.
And each runner is standing
at the correct distance from earth
of the galaxy they represent.
12.8 billion.
And 13 billion this way.
You get the biggest head start.
Cool!
So we've got our galaxies aligned.
Aligned.
Let's run it. Let's run it.
Let's see what happens.
Ok. All right.
But this is no ordinary race,
and there may be some surprises in store.
Will they work out what it means?
I'm expecting that when I pull the trigger
everyone will fly forward.
Galaxies ready.
Wow. Hey. You know what?
They're running at different speeds.
Well, I did say that this is no ordinary race.
Some of them jog,
some of them walk.
It took me a while to realize
what was happening.
There's no competition.
It's just... it's just how it's moving.
I wasn't expecting that.
So did I.
There should be a clue in that.
There's a clue in that. Right.
So clearly, the race isn't
about the physical prowess of each individual athlete.
It's gonna be more determined by the numbers
that we've assigned to them.
So so far, what we have learned?
13 billion.
13 billion is flying.
Yeah. She's superfast.
800,000 is walking. Ok.
The closer you were to the start line...
The start, yeah.
Um, the slower you move.
The secret that we discovered
was that galaxies that are the furthest away from earth
are also the ones traveling the fastest away from earth.
The further they get from earth,
the faster they travel.
My volunteers have discovered a vital clue
in Hubble's data.
Not only did Hubble's observation
of a Doppler red shift reveal galaxies
were moving away...
It revealed the most distant galaxies glowed
a deeper shade of red.
They were receding faster into the depths of the universe,
some at seemingly remarkable speeds.
These were absolutely revolutionary ideas,
and in the mid-1920s, this debate
about the nature of the world, the nature of reality
was at its most, uh, dramatic.
This extraordinary clue in Hubble's data
was a key turning point of discovering
where the universe came from.
Can my volunteers take the next step
to figure out what's making galaxies move the way they do?
- So... - Ok.
Quite clearly, we're in an ice rink.
Oh, yeah. Oh, my goodness.
To reveal the extraordinary truth
behind how the universe expands,
my volunteers will need to brave the ice.
We're gonna play ice hockey?
No.
We've got our galaxy jerseys again.
Oh, yeah. The galaxies are on jerseys.
We're gonna be the galaxies today.
We realized that there is some ice skating equipment,
so it doesn't take a genius to figure out
that we are going in the ice rink with them,
so that was quite... Quite scary.
So let's... so, um, I guess we're putting some kit on.
Their challenge is to replicate the big bang on ice
to work out why galaxies that are farthest from earth
move fastest.
First, they'll need to get their skates on...
But I've made an unusual addition to their skating gear.
On the table, there are leaf blowers
with balloons on them, which is very odd.
Shall we do it? Yeah.
Let's give it a go.
Oh. Oh, wow!
Will my volunteers work out what is making
galaxies move this way?
I think we should be on the ice.
Yeah. Let's go on the ice.
We figured that if head to the center
of the ice that would be a good place to start
in order to find out how we're actually
gonna reenact this big bang.
I can hardly do this... I know.
With a leaf blower.
I know. It's so hard to do with a leaf blower.
Aah! Oh!
I'm getting the hang of this. Okey-dokey.
We need to find a way
to use these balloons and these leaf blowers
to re-create how the galaxies are moving.
It's an explosion essentially, isn't it?
Right.
We're thinking that we need to cause some sort of explosion.
What do we have that is expanding?
Obviously, these balloons.
Do we put these balloons together maybe
and then that is the cause of the expansion?
So if we expand them against each other, we go backwards?
See if we go backwards. Oh, I like it.
We direct all of our blowers
toward each other.
1... 1...
2, 3. 2, 3.
Whoa! Ha ha ha!
Maybe we have to have it a little bit higher.
Agreed. Ok. Oh, my gosh.
All right, guys.
1, 2, 3.
Oh! Ha ha!
Unfortunately, the thing that lets us down
is our ability on the ice.
My volunteers may need a different strategy.
We need some help. Yeah.
We enlisted the pro team.
We were wondering if you could step in as our stuntmen.
So we approached these guys
and asked for 3 volunteers to take our place on the ice.
You want to come with me?
We squeezed them in together,
positioned the balloons where we wanted them,
and on the count of 3 asked them to switch them on.
Ok. 3, 2, 1, action.
Yeah. Thanks.
That was great, guys. Thank you.
It was clear that we had a principle
that was working,
but it wasn't quite the big bang
that we were looking for.
You want to scale it up?
Bring more players?
Get more players in?
More balloons, more players? Maybe.
Let's bring everybody in.
Now my volunteers are beginning to grasp
how an expanding universe could work.
Would you guys give us a hand?
Will their scaled-up simulation bring them closer
to finding out where the universe began?
Let's have some fun.
We'll start with our 3 guys that we did,
but then we'll create a line, a queue, if you like,
in behind each of the 3 guys in the middle.
How many you have there?
I have 5.
Ok. Are you ready guys?
Yeah!
All right. In 3, 2, 1, action!
So the balloons in the center inflate.
As the balloons were expanding,
the further back you were from the center,
the more speed you had, the more distance you traveled.
What do you think this is...
I think this explains why the galaxies
that were further way were moving...
Moving faster. Faster.
Faster than the ones who were...
Ah. That makes sense. At the beginning.
We discovered that those galaxies
are all moving away from each other,
um, and the further away they are from each other,
the faster they're moving away.
That was very interesting to see.
So what does this mean for the way
the universe is expanding?
We started to think about what is actually
causing the players to move.
If the galaxies are all moving away from each other,
what is it about the balloon that makes that happen?
The galaxies themselves aren't moving
or accelerating, controlling its speed.
It's just the space between them...
The space between them. Right.
That's... that's expanding.
Right. Yeah.
What's expanding is obviously
not the players.
The players are remaining the same,
and if the players represent galaxies,
then the galaxies aren't really expanding.
The balloons inflate, so space is inflating.
Right. So the galaxies are
kind of completely irrelevant themselves.
We have to focus on the space between the galaxies.
It is an eye-opening moment
when we realize it is the space what is expanding,
and that was very easy to see today
because we were able to see the balloons
pushing each player.
I'm coming to realizations
that things aren't the way I thought they were,
uh, and that's... that's what's really exciting here.
They've grasped it,
a concept scientists call the uniform expansion of space.
When the universe expands,
not everything in it expands, too.
So you should think of space expanding,
but the objects inside space, like galaxies and stars,
are not expanding.
They're standing the same size.
It's just as if you took space and stretched it uniformly.
So if given two points will be moving away
at some speed,
then if you take two points separated
by twice the distance,
they're moving away at twice the speed,
and that's Hubble's law.
Hubble's law, the observation of an expanding universe,
was a revelation,
but it wasn't a complete surprise
because Belgian cosmologist and priest Georges Lemaitre
had already worked on the theory behind it.
Lemaitre started off with this wonderful theory
that was around at this point,
which was Einstein's new theory of general relativity.
This beautiful set of equations were kind of ripe
for studying further and to applying
to our entire universe,
and this is what he wanted to try and understand
was he could he take this new theory of gravity
that Einstein had come up with
and apply it to the whole of space?
Einstein's equations tell us that space itself
gets distorted by the stuff that lives in space.
Matter bends space,
and space tells matter how to move in that space.
And so Lemaitre simplified the universe,
applied Einstein's theory to it,
and he discovered that if you fill space with stuff...
Uh, as we know it to be, the universe isn't completely empty...
Um, it should change, it should grow.
Lemaitre's theory that the universe was changing
was published in 1927.
It marked the birth of the big bang theory
and the revolution in how we understand our universe.
Now to piece together where the universe came from,
my volunteers will need to go over
what they've learned so far.
They have grasped the enormity of the universe's
200 billion galaxies.
It made me feel so small and insignificant.
They have discovered that the universe is expanding...
Whoo hoo hoo hoo!
As distant galaxies are moving away from us...
That thing flies!
And that those galaxies farthest from earth
move faster than those nearby...
Action!
Because space itself is uniformly expanding,
pushing galaxies further apart.
The galaxies themselves aren't moving.
It's just the space between them that's expanding.
Right.
But there's something about this uniform
expansion of space that has
extraordinary and unexpected consequences
that can tell us where the universe came from...
Something I hope my volunteers will uncover
in their final challenge.
Ok.
"Middle of the universe machine."
"1 billion years ago."
Well, that is a clue because that's
what we've been trying to find out,
where... where everything began.
I guess these represent galaxies.
And that's how the universe looked then.
What do we have on the other screen?
On the other screen, we have "now."
"Now."
The other screen says, "now."
They look pretty much the same.
They almost look identical.
But we're not lit.
But we're not lit up.
I think we should turn these on.
All right. Let's see.
The screens represent maps of a small part
of our universe,
and the lights represent galaxies.
Think of them as two snapshots of the same area of space
taken 1 billion years apart.
So how about we put our machine together?
Overlap the screens? Ok.
All right, guys. Get to it.
I'll direct you.
Marcia... Very clever... let the boys
carry the screen.
Ha ha ha! I wasn't gonna do any of the heavy lifting.
And we put the two screens
overlapping each other.
You're in? Is it in?
Yes, it's in now. Yeah.
Brilliant. Ok.
Ok.
We step back and have a look,
and it's clear that they're not the same.
Ha ha ha!
They're not the same.
They are not the same.
It looks like everything
is radiating out from a point.
So it looks from a billion years ago to... to today
everything has moved away slightly.
Same exact patterns.
Same patterns,
but they have moved.
It looked really good.
It looked amazing.
It was like jumping to warp speed
and you get that... pssheew... Starburst sort of effect, yeah.
And we figured out that that is supposed to
represent the expansion of space that we had seen
in our... our previous experiment.
So now we've got these galaxies.
They're all pointing to some black spot in space
as... as probably where they've all originated from.
The middle is where the universe began
because everything is... is moving away
from a single point.
So the significance of finding the middle
is to answer the big question...
Where... where did the big bang happen?
That's the idea.
So will my volunteers work out how to take
the next logical step to find where the universe began?
Maybe we can move this...
Move the screen?
Yeah. We can move the screen.
So we're gonna try to move it to align it.
Alejandro, if we get on the handles
and, Marcia, you tell us where you want it...
Ok. Brilliant. Ok.
Where do you want us to move it for?
To the left.
Left. Ok... oh. A little bit to the right,
then down a little bit more.
I think they'll be in for a surprise.
It really is straight down.
Down, down, down, down.
Huh. Ok, guys.
One galaxy in the middle is aligned.
Ok. And the rest?
And the rest of them are just slightly off.
Slightly off.
In a uniform manner.
I'm trying to explain this to you guys
so that you understand...
Because you c... You can't see it.
Well, why don't you come and hold this?
Let me have a look. Yeah, yeah. Perfect.
And then I can maybe... Perfect, perfect.
It looks like my volunteers
are about to uncover
what the uniform expansion of space means
for where the universe came from.
Oh, wow.
The team has figured out aligning their galaxies
is not as simple as it seems.
I so see what you mean now.
I see what you mean now.
They can only line up one galaxy
with its billion-year-older counterpart at a time.
How will they figure out what this could mean?
So we started to think
about how viewpoint made a difference
as to what it was we would see.
So we came up with the idea of perhaps changing our viewpoint.
So now I'm gonna pick another galaxy but on this side.
I'm gonna pick this galaxy now,
and I'm gonna align it up
with its billion-year-old partner behind, ok?
We'll go to Marcia.
Keep going. Keep going.
Keep going, keep going.
We picked a galaxy, um, and lined it up
with the one behind.
Keep going. Stop.
Perfect.
Ha ha!
So now I've made that the center of the universe,
everything else is moving out from that point.
Ha ha! And that was a... Not a light bulb moment,
but that was like a "Star Trek" moment.
This is visually incredible.
It's... it's cool. It really is.
It's really cool.
It was... it just changed.
The whole picture just changed.
Suddenly, the middle of the universe
seemed to change.
So everything was radiating from the galaxy I'd chosen.
Alejandro, you have to have a go at this.
Ok. I'm coming. Let's... let's do this.
Let me align two. You have to see it.
All right.
So how are we supposed to find
the middle of the universe
if every time we move it it changes?
I'm gonna choose this galaxy,
and I'm gonna align that one now.
Ok.
Now my volunteers are really on to something.
A little bit to the left.
Brilliant. From that point of view,
now I can see all of the galaxies
moving away from that,
and I think I'm on to something here.
Right.
So seemingly being able to make any point
at the center of the universe,
we start to slowly reject the idea
that we're gonna find a point in space
that is the center of the universe.
And that's when I start thinking
any single point could be the center.
I... i believe that this machine is telling us
that the middle of the universe
is a matter of our perspective.
Yep. Right?
It's wherever you're looking from.
Wherever you're looking from.
My volunteers have made
an extraordinary connection.
Everywhere is the center of the universe
because it all came into existence at the same time,
and it's all moving away from everywhere
at the same time.
Space didn't exist before the big bang.
Now space is expanding in all directions,
and these simple facts mean wherever you are
in the universe, it's the center,
where it all began.
So we did it.
We solved the question.
We know where the universe began.
We do. Here.
Heh. Right here.
Well done, team.
Brilliant. It was here all along.
Under our nose.
It was here all along.
Right under our nose.
That's where it began.
It was right under our nose all along, yeah.
To say that the universe started
at the tip of my nose, I'm just walking around,
like... ha ha ha... this is the coolest thing ever,
but obviously, if it started at the tip of my nose,
it could have started at the tip of everybody's nose.
They've got it
because at the big bang the tip of everyone's nose,
in fact all matter in the entire universe,
was one infinitely small point.
My volunteers have deciphered the vast and complex nature
of the universe,
and our journey has certainly thrown up
some pretty big thoughts.
I've learnt something most people don't know.
I've... I've learnt where the universe began.
I'm happy we came to that answer
because it makes perfect sense
and makes me look at the universe, the earth,
and in general my life from a completely different perspective.
I'm comfortable with being uncomfortable,
and I like it when things expand my mind.
The expansion of the universe described
by the big bang theory is one of the most important
intellectual discoveries of the 20th century.
It tells us where everything came from
and where we're going.
What happens next?
I believe the universe will continue to expand forever...
But at least we all know where it all began...
Right at the tip of your nose.
Have you ever wondered what you really are?
My name is Stephen Hawking.
I believe that anyone can answer big questions for themselves.
It's just amazing.
Follow the greatest thinkers in history.
Think like a genius.