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Planet Earth.

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Our home.

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It's unique.

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It has life.

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But what's amazing, is none
of it would exist without the sun,

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the moon and the stars around us.

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We are connected to the universe
in the most fundamental ways.

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To find out how, I'm going
to have to build my own.

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I'm going to open up
a cosmic tool-box and work it out.

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And I'm going to
build my universe up here,

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at the top of this
impossibly high tower.

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It gives us the perfect platform
to make something really big.

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Up here, we can do in seconds

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what it takes nature millions
or billions of years to do.

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And to build a universe, I'm going
to need a lot of help.

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I'll be honest, I'm faintly nervous.

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Was that it?

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Wow! Beautiful!

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Ohh, this is really difficult!

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I told you, seventies' moves!
There they are.

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Like any construction project,
there will be mistakes...

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..but from those mistakes, we'll
get real insights into what

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makes our universe
exactly right for us to exist.

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As an engineering challenge,

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this is about as big as it gets.

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How many times have you
marvelled at the stars?

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Depending upon your frame of mind,
the stars might appear distant

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and magical, or cold and remote,
but the fact is, we are all

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made of the same stuff. And if you
were to change anything about them,

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or about us, that connection, that
delicate balance, would be lost.

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And this isn't an idle fancy,
a romantic notion,

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it's essential, elemental and real.

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Without that connection,
we wouldn't be here.'

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And to understand how it works,
we need to build a universe.

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It's not a small task...

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..because Earth is in
a solar system...

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..which is in just
one tiny part of a galaxy...

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..that has over 300 billion
stars within it.

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And there are half a trillion
galaxies in the universe.

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So the job isn't really done
until we build it all,

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from suns to galaxies.

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I'm going to need to construct
all of this up here,

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at the top of my tower,

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where there's loads of room.

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To do this, we need to go back
to the very start of everything.

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We need to start from scratch.

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In the case of our universe,

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the start of everything was
13.8 billion years ago...

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about.

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I do like a challenge.

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Most scientists agree that before
the universe, there was nothing,

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nada.

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But out of that nothing,
was created something...

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everything. It all happened
in an event called the big bang.

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Thing is, the big bang is actually
a misleading name for it

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because it wasn't a bang at all.

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There is an analogy that scientists

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and boffins use to get their head
round this event.

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There's no explosion.
It wasn't a bang.

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It's more like a balloon.

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The big bang was a rapid expansion,
just like inflating a balloon.

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Now, of course,
the universe expanded

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a lot quicker than our balloon.

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Unimaginably so.

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In a billionth of a second,

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it was already
the size of our solar system.

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But you take the point.

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It's like a big expanding
bubble of space.

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But there's something even more
bizarre about the big bang.

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That universal expansion
had no single point of origin.

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It happened everywhere
and all at the same time.

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So one balloon isn't enough to
demonstrate it.

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I need countless balloons.

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What's more, the expansion of the
big bang is still happening today...

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..which means that wherever I am,

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I'm at the very centre
of an expanding universe.

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And wherever you are, you, too,
are at the centre of the universe.

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So we've had our big bang,
but there is a little problem.

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It's dark.

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There is no light after a big bang
because there are no stars.

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So, where can I get a star from?

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Well, fortunately, it turns out
they make them

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just off the M40 near Oxford.

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BUZZING AND BEEPING

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Inside this billion-pound

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chamber...

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..we're going to squeeze,

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using colossal magnets, the only
thing that was around after

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the big bang - hydrogen gas -
until it ignites.

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And that IS a star.

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BUZZING AND BEEPING

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Sounds simple? It isn't.
Don't try this at home.

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It is a job for the professionals.

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The chamber will briefly use more
power than a city like Birmingham.

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And the ignition countdown begins
100m away,

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in the relative safety
of mission control.

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We're now approaching the T minus
one minute mark. T minus one minute.

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I'm joining starmaker-in-chief,
Professor Steve Cowley.

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Steve, hello. Hello.

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I haven't touched anything
and I promise not to

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because you're effectively
creating a star here.

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Yeah.

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This looks AMAZING! This looks like
I'd want it to look.

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Is it running now?

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We're about to fire it up,
and for a few seconds,

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we'll reach the temperature
of round about 100 million degrees.

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100 million degrees!

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What if it goes wrong, Steve?

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I mean, it's kind of extreme,
isn't it?

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If something goes wrong,
and it does do,

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the physicist in charge,
she's got a red button,

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basically, and she will press the red
button and it will abort the shot.

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The amount of energy in there...

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This isn't that far from my
house is where I'm going!

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I live 50 miles away.

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But it does have a
wall that's 2m.

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ALARM CLANGS

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What's that?

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It's the panic button.
You have to run now.

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I'm not going to bother running.
Really, what would be the point?

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If something really did go wrong, you
could cause a lot of damage. Right.

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And I'm being allowed to give
the trigger command...

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..to turn it on.

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So, what I'm going to do now is

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trigger the creation of a star,
briefly, on Earth.

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Um...
CLEARS THROAT

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Er, trigger, please.

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Can you accelerate, please?

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OK. Thank you.

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INTERMITTENT BUZZING

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WHOOSHING

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COMPUTERISED VOICE: 'Start.'

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It's starting up now. Right.
Electrical current going through it.

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I'll be honest, I'm faintly nervous.

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How many times a day do you do this?

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'..Eight, seven, six, five, four,

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'three, two, one, zero.'

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There it is. Right.

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Look at the instability,
it's shaking.

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This is mind-blowing.

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Inside the chamber is hydrogen.

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It was pretty much the only thing
that existed in the darkness

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after the big bang.

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This machine heats
and squeezes the hydrogen

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with such force that it ignites,
creating a star and light.

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So, what's happening
in that chamber right now,

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there, that is...that is a star
on Earth.

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What's remarkable is the process of
making a star

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doesn't just create light.
It also makes brand-new ingredients,

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and this is going to help me
build our universe.

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There's little white specks, which
is exactly what stars are doing.

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It's turning hydrogen into helium.

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They start with hydrogen
and they make helium

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and then they get helium
and they make carbon,

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then they make oxygen. All
the things you're made of,

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they are made bit by bit by bit
in the centre of a star.

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Was that it? That's it.

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And was that the abort button
there, you had all the... Whoa...

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Within a star,
these different elements are made,

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but how do they then...
They've got to get elsewhere.

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So, if it's a big enough star,
it explodes -

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that's a supernova explosion -
and it spews all that stuff,

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all those things you've made,
all the carbon,

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all the iron, all the nickel, all the
whatever, right, spews it out

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into the universe as dust,
as particles,

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as this, that, and the other.

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These elements are created within it

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and then - boom! -
all over the universe.

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Stars not only give us light,

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they are the element factories
to build everything else.

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Back at my tower,
I can now make light,

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and create all the stuff to build
the rest of our universe.

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We just need a star
to go supernova.

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A supernova is the biggest
explosion there is, and for us

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it's an essential stage
in our construction process

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because it takes all those
elements created in big stars

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and scatters them everywhere.

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Just one note of caution though -

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when I say "big",
I do mean "really, really big".

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And that supernova has now
scattered all the ingredients

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we need to build everything.

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Floating around the tower,
we've now got carbon,

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oxygen,

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iron...

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..and all the other elements
we're going to need

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to make the planets,

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and even us.

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In that sense, everything

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really is stardust - you, me,

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everything you've ever seen

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or touched, or ever will.

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All of it created from
the birth and death of a star.

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It's mind-blowing.

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And that cloud of gas and dust,
called a nebula, also provides

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the ingredients for other stars.

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So we can now build our own
star from it.

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We'll call it the sun.

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The real one took around
50 million years to form.

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Here, we've done it in seconds.

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And orbiting it is
the dust and gas we'll need

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to make all the planets
in our solar system.

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00:15:34,140 --> 00:15:37,460
The first planet to start forming
is Jupiter.

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But something's not going to plan.

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The young planet
is starting to hoover up

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00:15:45,380 --> 00:15:48,220
way too much of the gas and rock.

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And this process

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is slowing it down...

208
00:15:56,660 --> 00:16:01,220
..causing it to fall inwards,
towards the sun.

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00:16:01,220 --> 00:16:03,660
Which is a problem,

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because this is the very stuff

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00:16:05,540 --> 00:16:07,740
that's going to build
all the other planets.

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00:16:07,740 --> 00:16:11,180
It's bad. What do we do to stop
Jupiter gobbling up

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00:16:11,180 --> 00:16:13,620
all our planetary
building materials?

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00:16:13,620 --> 00:16:16,460
Well, fortunately,
I'm told there is a man who knows.

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00:16:22,740 --> 00:16:26,540
This is Professor Alexei Filippenko.

216
00:16:30,260 --> 00:16:34,100
And THIS is a Fresnel lens.

217
00:16:35,700 --> 00:16:39,340
A simple enough device,
but surprisingly powerful.

218
00:16:43,260 --> 00:16:47,540
Hi, Richard. So, how do we get rid
of our rampaging Jupiter problem?

219
00:16:47,540 --> 00:16:51,380
Oh, well, look. Let me show you a
demo that'll help illustrate it.

220
00:16:51,380 --> 00:16:55,460
Declan, why don't you tilt it there?

221
00:16:55,460 --> 00:16:58,740
It's on fire. Right away!
It is on fire!

222
00:16:58,740 --> 00:17:02,180
But what's that got to do with
Jupiter? It's a bit of wood?

223
00:17:02,180 --> 00:17:05,460
Yeah, well, what's happening is
there's all these photons, all these

224
00:17:05,460 --> 00:17:08,860
little energetic particles of light
coming from the sun and they're

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00:17:08,860 --> 00:17:12,540
being focused here on this wood,
heating it up, causing it to burn.

226
00:17:12,540 --> 00:17:16,100
In the case of the early solar
system, the sun was much

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00:17:16,100 --> 00:17:19,180
brighter than it is now and it
acted for hundreds of thousands,

228
00:17:19,180 --> 00:17:22,860
or millions of years,
so the photons were hitting

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00:17:22,860 --> 00:17:27,140
the particles of dust and gas
and heating them up, causing the

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00:17:27,140 --> 00:17:31,420
atoms to actually evaporate away,
to be blown out of the solar system.

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00:17:31,420 --> 00:17:34,380
That meant that Jupiter
was no longer

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slowing down
and spiralling into the sun.

233
00:17:36,580 --> 00:17:39,740
Two things. One -
there's a small fire over there.

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00:17:39,740 --> 00:17:41,060
Yeah! Two -

235
00:17:41,060 --> 00:17:44,660
all the stuff in the way of Jupiter,
slowing it up, wasn't wood.

236
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Yeah, I know,
but look how powerful the sun is.

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00:17:47,180 --> 00:17:49,460
Here's a rock.
Why don't you put it right there.

238
00:17:49,460 --> 00:17:51,340
I don't want to get zapped
by your machine.

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00:17:51,340 --> 00:17:53,700
Declan won't zap you
while you're putting it there.

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00:17:53,700 --> 00:17:56,500
And we need to have some
safety glasses on because

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00:17:56,500 --> 00:17:59,700
it's going to get heated up so much
from the trillions of photons

242
00:17:59,700 --> 00:18:03,300
hitting it that, er, it's actually
going to snap, crackle and pop.

243
00:18:03,300 --> 00:18:06,340
Little pieces will come flying out.
You've got more safety than me.

244
00:18:06,340 --> 00:18:08,380
Well, you know,
my eyes are more important.

245
00:18:08,380 --> 00:18:11,020
I'm an astronomer, OK? OK.
So let's put the rock in there...

246
00:18:11,020 --> 00:18:12,300
I can't argue with that, can I?

247
00:18:12,300 --> 00:18:14,060
I can't argue with that.
I think you're OK.

248
00:18:16,140 --> 00:18:17,700
CRACKING AND POPPING

249
00:18:17,700 --> 00:18:19,020
Oh, hang on, that is the rock.

250
00:18:19,020 --> 00:18:21,580
Yeah, that's the rock flaking off...

251
00:18:21,580 --> 00:18:24,860
because of all the energetic photons
hitting it.

252
00:18:24,860 --> 00:18:29,020
I am properly impressed with that.
That is in seconds.

253
00:18:29,020 --> 00:18:32,340
It's heating up to 3,000 degrees
Fahrenheit, OK?

254
00:18:32,340 --> 00:18:34,980
Now, over millions of years,

255
00:18:34,980 --> 00:18:38,820
the material is being blown out
of the vicinity of Jupiter,

256
00:18:38,820 --> 00:18:42,740
so it's not growing any more and also
it's not spiralling into the sun.

257
00:18:42,740 --> 00:18:45,860
So that saves us.
Turn it off, Declan, I'm terrified.

258
00:18:45,860 --> 00:18:49,220
So this is another one of those
events that had to happen

259
00:18:49,220 --> 00:18:52,860
at the right time, in the right
place, and to the right extent.

260
00:18:52,860 --> 00:18:54,220
Too much of this for too long

261
00:18:54,220 --> 00:18:56,780
and there's nothing left to make
your inner planets from.

262
00:18:56,780 --> 00:18:58,020
Yeah, that's exactly right.

263
00:19:02,620 --> 00:19:04,220
OK, a plan.

264
00:19:09,740 --> 00:19:14,060
I'm going to use light from the sun
to clear a path for Jupiter...

265
00:19:16,420 --> 00:19:19,260
..to stop it slowing
and spiralling inwards,

266
00:19:19,260 --> 00:19:22,860
gobbling all the building materials
for our other planets.

267
00:19:24,340 --> 00:19:26,980
So, let's crank up
the light from our sun...

268
00:19:30,100 --> 00:19:32,260
..and get those photons pumping.

269
00:19:47,820 --> 00:19:50,540
Jupiter's way is now clear.

270
00:19:52,820 --> 00:19:56,260
But luckily for us,
the perfect amount of stuff

271
00:19:56,260 --> 00:19:59,660
is left behind to build
the rest of our solar system.

272
00:20:01,740 --> 00:20:03,740
So we've got Jupiter.

273
00:20:07,020 --> 00:20:09,020
Now, how do we make
our other planets?

274
00:20:11,100 --> 00:20:14,540
To find out what the planet
formation was like in the early

275
00:20:14,540 --> 00:20:17,700
solar system, I need the help
of the Texas Roller Derby.

276
00:20:17,700 --> 00:20:19,260
Excuse me. Sorry.

277
00:20:22,740 --> 00:20:24,060
Course I do.

278
00:20:24,060 --> 00:20:27,140
Sorry, ladies, excuse me.
Can I join?

279
00:20:27,140 --> 00:20:29,860
Oh! Do I really need that?
You need it to protect your head.

280
00:20:29,860 --> 00:20:33,140
Right. Well, I'll pop it on.
Thank you.

281
00:20:33,140 --> 00:20:37,820
What's your skate name? Your name
on the track, your alter ego?

282
00:20:39,100 --> 00:20:41,340
Hamster. Yeah, it's a long story.

283
00:20:41,340 --> 00:20:43,300
What about Slamster? Slamster!

284
00:20:43,300 --> 00:20:46,220
Oh! I'm loving that!
WOMEN: Yeah, that's good.

285
00:20:46,220 --> 00:20:49,100
What sort of injuries
can you acquire doing this?

286
00:20:49,100 --> 00:20:51,860
BOTH: Broken...everything!

287
00:20:51,860 --> 00:20:55,740
Broken ankles.
Broken teeth. Hands, arms...

288
00:20:55,740 --> 00:20:56,940
I am really scared!

289
00:20:57,980 --> 00:21:00,100
You should be scared.

290
00:21:00,100 --> 00:21:02,180
Now, I know what you're thinking.

291
00:21:02,180 --> 00:21:05,060
Actually, I've no idea what
you're thinking...

292
00:21:06,300 --> 00:21:09,540
..but bear with me. This is a
genuine scientific demonstration

293
00:21:09,540 --> 00:21:12,220
of what happened
in the early solar system.

294
00:21:13,420 --> 00:21:16,780
See you out there, girls.
Oh, scared!

295
00:21:19,020 --> 00:21:23,180
I should say, I'm not what
you'd call a regular skater.

296
00:21:33,540 --> 00:21:38,020
Imagine the sun in the centre
of the track providing the gravity

297
00:21:38,020 --> 00:21:42,660
to pull around a whole
host of rocks of different sizes.

298
00:21:42,660 --> 00:21:45,580
These wannabe planets
are known as planetesimals.

299
00:21:50,780 --> 00:21:55,980
Some of these planetesimals
were large, some very small,

300
00:21:55,980 --> 00:21:58,380
some moving in crazy orbits.

301
00:21:59,940 --> 00:22:01,540
U-u-ugh! Yee-ugh! Whoo-uh!

302
00:22:04,620 --> 00:22:07,700
All of them were affected
by one another's gravity.

303
00:22:10,540 --> 00:22:12,740
So there were HUGE collisions.

304
00:22:15,820 --> 00:22:19,220
Potential planets were
flung out of the solar system.

305
00:22:33,660 --> 00:22:36,420
And some wannabe planets
were destroyed.

306
00:22:37,660 --> 00:22:41,380
Others had huge chunks
ripped off them.

307
00:22:44,620 --> 00:22:47,060
What happened over
just a few million years

308
00:22:47,060 --> 00:22:49,100
was a sort of planetary carnage.

309
00:22:54,780 --> 00:22:58,740
Oh! This is really difficult!
Ha-ha-ha... Whoo-ooh!

310
00:23:08,380 --> 00:23:12,340
Eventually, some of the larger,
more stable planets emerged

311
00:23:12,340 --> 00:23:15,340
and took the outside orbital lane.

312
00:23:15,340 --> 00:23:19,140
Whilst closer to the sun, smaller
planets jostled for position.

313
00:23:23,300 --> 00:23:26,060
The remnants of this orbital tussle,
the dead

314
00:23:26,060 --> 00:23:31,300
and never-to-be planets didn't just
disappear, they still exist.

315
00:23:35,020 --> 00:23:37,860
A graveyard of broken worlds

316
00:23:37,860 --> 00:23:41,700
now orbits the sun
as a ring of debris

317
00:23:41,700 --> 00:23:43,540
known as the asteroid belt.

318
00:23:47,860 --> 00:23:52,380
So here we are. Our solar system.
There's Jupiter

319
00:23:52,380 --> 00:23:54,500
and, alongside
it, the asteroid belt.

320
00:23:57,980 --> 00:24:01,060
And then the rest of the planets
in our solar system.

321
00:24:02,980 --> 00:24:05,900
There's Mercury, nearest the sun.

322
00:24:07,060 --> 00:24:10,180
Its atmosphere
has already been burnt away.

323
00:24:12,820 --> 00:24:15,220
Then Venus,

324
00:24:15,220 --> 00:24:18,700
a big bash early on
has reversed its spin.

325
00:24:21,140 --> 00:24:22,740
And Mars,

326
00:24:22,740 --> 00:24:25,180
there's an enormous volcano here...

327
00:24:26,700 --> 00:24:31,580
..Olympus Mons,
three times higher than Everest.

328
00:24:36,620 --> 00:24:40,420
Then Jupiter, bigger than all
the planets put together.

329
00:24:44,340 --> 00:24:47,540
Saturn with its amazing rings.

330
00:24:48,740 --> 00:24:51,380
So light, it could float on water.

331
00:24:54,140 --> 00:25:00,500
Further out, Uranus, where summers
last 21 Earth years, as do winters!

332
00:25:02,460 --> 00:25:05,100
And finally, Neptune.

333
00:25:06,460 --> 00:25:11,420
Freezing cold with hurricane
winds of 1,000 kilometres an hour.

334
00:25:16,700 --> 00:25:20,620
Of course, there is
one planet missing - ours.

335
00:25:20,620 --> 00:25:23,900
And exactly where it goes
is critical

336
00:25:23,900 --> 00:25:28,740
because we need it to support
one very fragile thing - life.

337
00:25:32,620 --> 00:25:36,460
Earth is unique amongst
the planets in our solar system.

338
00:25:37,900 --> 00:25:39,540
It teems with life.

339
00:25:41,500 --> 00:25:45,060
Life which comes in
countless different forms.

340
00:25:50,900 --> 00:25:54,540
So what is it
that makes Earth so special?

341
00:25:57,500 --> 00:26:02,180
What do we need for life to exist
when we're building a solar system?

342
00:26:17,500 --> 00:26:21,380
To find out, these scientists
are attempting to reach

343
00:26:21,380 --> 00:26:26,020
one of the most inhospitable
and extreme places on Earth.

344
00:26:27,460 --> 00:26:28,860
Sandro...

345
00:26:28,860 --> 00:26:31,180
SHE SPEAKS ITALIAN

346
00:26:31,180 --> 00:26:32,740
How far is it to the lake?

347
00:26:34,540 --> 00:26:37,820
SHE CONTINUES IN ITALIAN

348
00:26:37,820 --> 00:26:42,300
Where they're heading is so toxic,
it is like an alien planet.

349
00:26:45,340 --> 00:26:49,700
If they can find life down there,
it will help us understand

350
00:26:49,700 --> 00:26:54,060
the most basic requirements
for life in our solar system.

351
00:26:54,060 --> 00:26:56,500
OK, I'll follow you.

352
00:26:56,500 --> 00:26:57,900
Be careful.

353
00:26:59,340 --> 00:27:03,620
To get there, they must risk
a perilous 3km descent

354
00:27:03,620 --> 00:27:06,660
into eastern Italy's
Frasassi cave system.

355
00:27:25,340 --> 00:27:31,380
Caves like these contain some of the
last unexplored frontiers on Earth.

356
00:27:33,460 --> 00:27:35,100
Here I come.

357
00:27:37,100 --> 00:27:39,060
The expedition is led by

358
00:27:39,060 --> 00:27:42,460
astrobiologist
Professor Jenn Macalady.

359
00:27:43,820 --> 00:27:45,460
Stay left, it's really tight.

360
00:27:46,900 --> 00:27:50,660
If you go to the right you are going
to get stuck for sure.

361
00:27:50,660 --> 00:27:52,780
I'm not far behind.

362
00:27:52,780 --> 00:27:53,900
Use your feet.

363
00:27:53,900 --> 00:27:56,860
Yes, I am, it's er...

364
00:27:56,860 --> 00:27:58,660
tight.

365
00:27:58,660 --> 00:27:59,780
Breathe out.

366
00:28:01,300 --> 00:28:02,380
Yeah, that's it.

367
00:28:06,980 --> 00:28:08,420
You got it? Yep.

368
00:28:08,420 --> 00:28:10,740
You're through! Awesome.

369
00:28:10,740 --> 00:28:13,460
The things I do for science!

370
00:28:17,500 --> 00:28:20,900
After six hours, they're
approaching the final descent.

371
00:28:24,540 --> 00:28:28,740
At the bottom, Jenn's hoping to
shed light on the minimal

372
00:28:28,740 --> 00:28:30,740
conditions required for life.

373
00:28:31,780 --> 00:28:33,180
Aldo, coming down. OK!

374
00:28:41,700 --> 00:28:44,580
This is the Crystal Lake.

375
00:28:44,580 --> 00:28:46,380
Wow, it's beautiful.

376
00:28:49,180 --> 00:28:50,820
OK, I'm going down.

377
00:28:50,820 --> 00:28:54,700
Deep below its surface is home
to what Jenn is looking for.

378
00:28:57,900 --> 00:28:59,580
It's a long way down, folks.

379
00:29:03,060 --> 00:29:05,700
Down here, all the normal things

380
00:29:05,700 --> 00:29:08,540
you need to support life
have disappeared.

381
00:29:09,580 --> 00:29:11,980
Shall I come all the way down?

382
00:29:11,980 --> 00:29:13,620
There is no light.

383
00:29:15,020 --> 00:29:18,540
No animals or plants to feed off.

384
00:29:18,540 --> 00:29:21,820
And where they're going,
there's no oxygen.

385
00:29:23,180 --> 00:29:24,340
We made it.

386
00:29:29,660 --> 00:29:32,500
The water is even poisonous

387
00:29:32,500 --> 00:29:35,420
but Jenn is hoping to find
life there.

388
00:29:39,180 --> 00:29:43,500
The hunt will involve one of the
most dangerous dives on the planet.

389
00:29:44,740 --> 00:29:49,980
Preparing to make the 80-foot plunge
is ex-Navy diver Alejandro Crocetti.

390
00:29:51,900 --> 00:29:52,820
Perfecto.

391
00:29:54,220 --> 00:29:56,820
His dive time is strictly limited.

392
00:29:59,740 --> 00:30:02,220
Any kind of cave diving
is very dangerous, because

393
00:30:02,220 --> 00:30:04,900
if there's a problem, you can't
just pop up to the surface.

394
00:30:04,900 --> 00:30:06,420
You have a long way to go.

395
00:30:07,860 --> 00:30:11,700
But also, in this particular case,
the water is actually toxic.

396
00:30:11,700 --> 00:30:14,980
So the chemicals that are dissolved
in the water come through the skin,

397
00:30:14,980 --> 00:30:19,620
so that if you stay in that water
for a while, then you become sick.

398
00:30:22,420 --> 00:30:23,900
You start to have symptoms

399
00:30:23,900 --> 00:30:26,340
that prevent you
from making good decisions.

400
00:30:27,980 --> 00:30:31,540
Very quickly the passages
become tighter and tighter.

401
00:30:31,540 --> 00:30:34,180
There is no room to manoeuvre.

402
00:30:34,180 --> 00:30:38,980
As soon as you move, you suspend
all the sediment that's on the bottom

403
00:30:38,980 --> 00:30:41,620
and the visibility goes to zero
very quickly.

404
00:30:43,580 --> 00:30:46,460
Fish would die instantly here.

405
00:30:48,460 --> 00:30:52,340
Very quickly the water will become
sulphidic, more cloudy,

406
00:30:52,340 --> 00:30:54,180
more difficult to navigate through.

407
00:30:55,580 --> 00:30:57,740
We're not meant to be there really.

408
00:30:57,740 --> 00:31:00,620
It's a place where we can
stay only for a few moments.

409
00:31:14,740 --> 00:31:17,900
Finally, they find what
they've been looking for.

410
00:31:24,540 --> 00:31:28,380
These weird alien fingers are alive.

411
00:31:32,340 --> 00:31:34,020
They are bacteria,

412
00:31:34,020 --> 00:31:38,420
living on nothing more than rock
dissolved in toxic water.

413
00:31:49,860 --> 00:31:51,620
Wow!

414
00:31:51,620 --> 00:31:52,980
Wow!

415
00:31:54,060 --> 00:31:56,900
Look at that, this is beautiful.

416
00:31:58,100 --> 00:31:59,420
Were there a lot like this?

417
00:31:59,420 --> 00:32:02,940
Multi. Multi? Si.

418
00:32:02,940 --> 00:32:06,260
Amazing sample, bravo. Grazie.

419
00:32:16,460 --> 00:32:19,460
This is life that we don't
really understand yet.

420
00:32:19,460 --> 00:32:24,220
It's from water that's toxic,
it's hostile, there's no oxygen.

421
00:32:24,220 --> 00:32:27,780
Where we've lost all the light,
almost nothing to live on.

422
00:32:27,780 --> 00:32:30,660
All that's left really is water
and rocks,

423
00:32:30,660 --> 00:32:37,140
and yet there's this beautiful form
just full of interesting, weird,

424
00:32:37,140 --> 00:32:41,620
strange life, and it's
extraordinary, because it represents

425
00:32:41,620 --> 00:32:47,260
something new that will help us
explore for life on other planets.

426
00:32:50,780 --> 00:32:53,980
One of the things that we can learn
from a sample like this is that

427
00:32:53,980 --> 00:32:58,980
wherever we have rocks and water,
then somehow

428
00:32:58,980 --> 00:33:03,100
the water is going to allow life
to thrive

429
00:33:03,100 --> 00:33:05,180
because it allows things to mix.

430
00:33:05,180 --> 00:33:08,020
It allows the rock
to interact with life.

431
00:33:09,540 --> 00:33:14,740
So water is really, as we understand
life, the most essential ingredient.

432
00:33:22,820 --> 00:33:26,700
Life as we know it can't exist
without water

433
00:33:26,700 --> 00:33:29,060
but it must be liquid.

434
00:33:29,060 --> 00:33:32,660
Water, of course, comes in
several different states.

435
00:33:37,540 --> 00:33:41,140
And where it is
in our solar system is key.

436
00:33:42,860 --> 00:33:46,700
Too close to our sun,
and water boils away.

437
00:33:49,820 --> 00:33:53,020
Too far away,
like in the rings of Saturn...

438
00:33:54,540 --> 00:33:57,740
..and water freezes as hard as iron.

439
00:34:07,780 --> 00:34:10,540
Where we place our planet,
then, is critical

440
00:34:10,540 --> 00:34:12,900
if we want to have liquid water.

441
00:34:12,900 --> 00:34:17,420
But how much leeway do we have?
What about here near Mars,

442
00:34:17,420 --> 00:34:20,260
about 142 million miles
from the sun?

443
00:34:26,220 --> 00:34:30,460
Well, to find out if Mars
is suitable for liquid water,

444
00:34:30,460 --> 00:34:33,700
and for life,
first you've got to get there.

445
00:34:38,660 --> 00:34:39,820
Mars.

446
00:34:44,020 --> 00:34:48,580
And NASA's rover,
driving on the surface.

447
00:34:51,820 --> 00:34:54,660
Well, as close as you can
get to its surface...

448
00:34:56,500 --> 00:34:58,740
..in Houston, Texas.

449
00:34:58,740 --> 00:35:01,580
Don't look at the bulldozer, that
gives away that it's not Mars.

450
00:35:01,580 --> 00:35:03,180
Just so you know, that's not there!

451
00:35:03,180 --> 00:35:05,620
Or those cars. It spoils the effect!

452
00:35:07,660 --> 00:35:11,900
And my guide is NASA astronaut,
Mike Gernhardt.

453
00:35:11,900 --> 00:35:13,940
Would it look anything like this?
Yeah.

454
00:35:18,420 --> 00:35:23,220
NASA wants to put humans on the
Red Planet in the next 20 years.

455
00:35:24,580 --> 00:35:26,980
Their goal is to find life.

456
00:35:32,340 --> 00:35:36,980
Problem is, despite there being
hundreds of old river beds on Mars,

457
00:35:36,980 --> 00:35:41,020
all images show that the liquid
water has vanished from the surface.

458
00:35:46,940 --> 00:35:48,380
So, what's happened to it?

459
00:35:51,580 --> 00:35:56,660
NASA is developing the kit to take
us to the Red Planet to find out.

460
00:35:58,020 --> 00:36:00,300
This is Building Nine.

461
00:36:01,900 --> 00:36:04,460
A place I dreamt of as a kid...

462
00:36:05,700 --> 00:36:06,980
..and as an adult.

463
00:36:10,180 --> 00:36:12,580
You do have the coolest garage
in the world.

464
00:36:12,580 --> 00:36:15,940
Yep, we got some really cool stuff.
This thing is called the Robonaut.

465
00:36:15,940 --> 00:36:19,180
This is actually on the International
Space Station at this point.

466
00:36:19,180 --> 00:36:21,780
This is called
the Space Exploration Vehicle.

467
00:36:21,780 --> 00:36:24,780
This would be going to
an asteroid, or possibly

468
00:36:24,780 --> 00:36:26,860
a moon of Mars like Phobos.

469
00:36:26,860 --> 00:36:30,180
Then with the reaction-controlled
jets, we can hop.

470
00:36:30,180 --> 00:36:33,260
And an astronaut is on the end
of a robot arm and we can have

471
00:36:33,260 --> 00:36:37,220
that on Mars, or the moon, or
whatever planets we end up going to.

472
00:36:37,220 --> 00:36:42,260
All of this really informs us how to
support these deep space missions.

473
00:36:42,260 --> 00:36:45,660
It's... Talking to you is just like
going through a movie plot,

474
00:36:45,660 --> 00:36:47,620
constantly, it's so...

475
00:36:47,620 --> 00:36:51,340
Right, that all makes perfect
sense...if you're you.

476
00:36:51,340 --> 00:36:54,420
RECORDING: 'We're now approaching
the T minus one minute mark.

477
00:36:54,420 --> 00:36:56,740
'T minus one minute.
T minus one minute.'

478
00:36:56,740 --> 00:37:01,220
And this is how man might get to
Mars - the Orion spaceship.

479
00:37:01,220 --> 00:37:04,260
Are we getting in?
We're going to get in.

480
00:37:04,260 --> 00:37:07,500
Oh! I so want to get in.
A born astronaut, me.

481
00:37:07,500 --> 00:37:10,580
Here I go! Right, climbing across.

482
00:37:10,580 --> 00:37:12,980
You could bang your head
on many things in here.

483
00:37:12,980 --> 00:37:14,620
Ye-ow!

484
00:37:14,620 --> 00:37:16,660
Yeah. Oh, yeah.

485
00:37:17,860 --> 00:37:21,580
Ooh! Yeah, I am so in.

486
00:37:21,580 --> 00:37:22,940
All right, good job!

487
00:37:22,940 --> 00:37:24,580
'T minus 20 seconds and counting.'

488
00:37:24,580 --> 00:37:27,900
'Having been to space,
Mike's going to take me

489
00:37:27,900 --> 00:37:30,700
'through what a Mars launch
would be like.'

490
00:37:30,700 --> 00:37:32,500
So, you climb in here.

491
00:37:32,500 --> 00:37:35,540
'Ten, nine...' You're strapped in.

492
00:37:35,540 --> 00:37:37,420
'Ignition sequence has started.'

493
00:37:37,420 --> 00:37:39,380
Then there's check lists
you go through.

494
00:37:39,380 --> 00:37:40,900
'Five, four...'

495
00:37:40,900 --> 00:37:44,260
The clock hits zero...
'..two, one, zero...'

496
00:37:44,260 --> 00:37:47,740
..and, all of a sudden, you have
this big thrust in your back.

497
00:37:50,980 --> 00:37:52,860
And you're going up into space.

498
00:37:54,180 --> 00:37:56,220
'And we have liftoff.'

499
00:37:59,820 --> 00:38:03,980
We're going to be going faster
than we ever have before

500
00:38:03,980 --> 00:38:07,220
so it's going to be a, you know,
a real sporty ride.

501
00:38:07,220 --> 00:38:09,660
Sporty, that's a good word.
Vigorous.

502
00:38:10,740 --> 00:38:12,700
'Liftoff...'

503
00:38:12,700 --> 00:38:16,500
So, four of us in here? Yep.

504
00:38:16,500 --> 00:38:17,940
Mars. Mars.

505
00:38:17,940 --> 00:38:20,020
It's not a short trip, is it?
It isn't.

506
00:38:20,020 --> 00:38:23,140
Generally think of it
as a nine-month trip out.

507
00:38:23,140 --> 00:38:25,260
Nine months?!

508
00:38:25,260 --> 00:38:26,740
What if somebody snores? I snore.

509
00:38:26,740 --> 00:38:29,340
I have actually flown in space
with a guy that snored

510
00:38:29,340 --> 00:38:32,220
so loud that it kept me
awake for days actually.

511
00:38:32,220 --> 00:38:34,740
Were you not just tempted to,
you know, let him out?

512
00:38:34,740 --> 00:38:36,420
Nah, you can't do that.

513
00:38:36,420 --> 00:38:38,380
'OK, Houston, go in 30 seconds.'

514
00:38:38,380 --> 00:38:39,740
INDISTINCT RESPONSE

515
00:38:39,740 --> 00:38:41,500
'Mark one bravo.'

516
00:38:43,340 --> 00:38:47,060
Having reached the Red Planet,
we now need to get out

517
00:38:47,060 --> 00:38:49,260
and search for Mars's water.

518
00:38:50,900 --> 00:38:53,340
So, I'll need one of these.

519
00:38:54,740 --> 00:38:58,620
Can I just say, this is an amazing
privilege to get to do this.

520
00:38:58,620 --> 00:39:02,860
This is the Z1, next gen prototype.

521
00:39:02,860 --> 00:39:07,540
Besides me, Bruce Willis is the
only non-astronaut who's ever been

522
00:39:07,540 --> 00:39:10,580
cleared to wear a real spacesuit.
Oh, yeah.

523
00:39:10,580 --> 00:39:13,140
It's kind of like putting on
a big onesie.

524
00:39:13,140 --> 00:39:14,740
Do I look faintly ridiculous?

525
00:39:14,740 --> 00:39:16,580
Ha-ha, yes!

526
00:39:19,220 --> 00:39:22,020
Wow! That's a glove and a half.

527
00:39:22,020 --> 00:39:23,660
That is serious.

528
00:39:25,420 --> 00:39:27,260
The NASA team are now putting me

529
00:39:27,260 --> 00:39:30,660
through a full Mars
atmosphere suit simulation.

530
00:39:30,660 --> 00:39:32,980
That's got to go all the way up
until we get to four three,

531
00:39:32,980 --> 00:39:36,620
which is operating pressure. OK.
Sound good? Yes. OK

532
00:39:42,940 --> 00:39:46,260
I'm waiting for a massive
burst of claustrophobia.

533
00:39:47,140 --> 00:39:52,860
'The atmosphere on Mars is
incredibly thin, just 1% of Earth's,

534
00:39:52,860 --> 00:39:56,660
'so we need to pump up the suit,
like inflating a tyre,

535
00:39:56,660 --> 00:39:57,940
'to hold my body together.'

536
00:39:57,940 --> 00:40:00,700
Swallowing. You're looking
worried. Doing OK? I'm fine!

537
00:40:00,700 --> 00:40:03,940
Great. You're starting to look
more muscular now, you know.

538
00:40:03,940 --> 00:40:06,260
No, I actually am, I'm actually
flexing. We're at three.

539
00:40:06,260 --> 00:40:07,820
Three PSI. Three PSI.

540
00:40:07,820 --> 00:40:09,700
Four, one.

541
00:40:09,700 --> 00:40:12,300
Four, one. Popping ears.

542
00:40:12,300 --> 00:40:15,580
We're at operating pressure.
Operating pressure. Wow!

543
00:40:15,580 --> 00:40:18,060
So, the arms are a little bit
long for you in the suit

544
00:40:18,060 --> 00:40:21,300
but that's as small as they go
because you're at the small end...

545
00:40:21,300 --> 00:40:24,540
This is like every shopping trip
I've ever been on!

546
00:40:24,540 --> 00:40:26,580
The legs are a bit
long on the jeans, sir,

547
00:40:26,580 --> 00:40:29,020
but that's the shortest we have.
All right!

548
00:40:29,020 --> 00:40:30,820
OK! Yeah, it's...

549
00:40:30,820 --> 00:40:33,100
Why did I know it wasn't
going to fit?

550
00:40:33,100 --> 00:40:36,100
So the next thing, we're going to
release you from the donning stand.

551
00:40:42,020 --> 00:40:45,260
I only have short legs,
so the bigger steps thing...

552
00:40:48,940 --> 00:40:50,780
MUSIC: "Stayin' Alive"
The Bee Gees

553
00:40:56,500 --> 00:41:00,100
It had to happen. I told you -
seventies' moves, there they are.

554
00:41:00,100 --> 00:41:01,540
I am super impressed.

555
00:41:01,540 --> 00:41:05,220
My daughters will be just cringing,
"Dad, don't dance!"

556
00:41:05,220 --> 00:41:09,580
I'm dancing, yeah.
See, look, girls, there it is.

557
00:41:09,580 --> 00:41:12,140
Suddenly I feel like doing
this a lot.

558
00:41:12,140 --> 00:41:14,300
Oh, yeah, moonwalk!

559
00:41:18,980 --> 00:41:20,740
Were I on Mars right now,

560
00:41:20,740 --> 00:41:23,860
the atmosphere on the other side of
this suit would be very different.

561
00:41:23,860 --> 00:41:27,500
What's it like? Yeah, it's
basically almost no atmosphere.

562
00:41:27,500 --> 00:41:30,940
As we stand here, we're at
14.7 pounds per square inch,

563
00:41:30,940 --> 00:41:33,420
on Mars the pressure is
roughly ten torr,

564
00:41:33,420 --> 00:41:35,620
which is like
one hundredth of this.

565
00:41:36,860 --> 00:41:39,540
What would happen to me
if I didn't have this?

566
00:41:39,540 --> 00:41:41,900
You'd be dead pretty soon.
You'd probably have

567
00:41:41,900 --> 00:41:44,860
a couple to three minutes,
and then that would be it.

568
00:41:44,860 --> 00:41:49,260
Clearly that's bad. Well,
thank heavens for this thing then.

569
00:41:49,260 --> 00:41:52,660
'Mars is relatively close to Earth,

570
00:41:52,660 --> 00:41:55,140
'yet we certainly couldn't
live there.

571
00:41:55,140 --> 00:41:58,780
'So, for life,
what's wrong with the Red Planet?'

572
00:41:58,780 --> 00:42:05,500
Well, Mike's going to show us, with
just a glass of water and a pump.

573
00:42:09,340 --> 00:42:12,300
So that's a pump and you're just
pumping the air out of here

574
00:42:12,300 --> 00:42:14,900
until, you're creating
a vacuum in there. Exactly.

575
00:42:14,900 --> 00:42:17,260
It actually won't be a pure vacuum,
it'll be the same

576
00:42:17,260 --> 00:42:22,340
pressure as we have on Mars, which
is very low but not complete vacuum.

577
00:42:22,340 --> 00:42:25,940
So you're just taking the air out
to lower the pressure. Exactly.

578
00:42:28,620 --> 00:42:30,380
There it goes. There it goes.

579
00:42:31,700 --> 00:42:35,380
So there's no extra heat in there,
that isn't at 100 degrees C?

580
00:42:35,380 --> 00:42:37,580
In fact that could be at
zero degrees C.

581
00:42:42,020 --> 00:42:44,940
This is why you should always be
careful with your spacesuit on Mars.

582
00:42:44,940 --> 00:42:46,220
Exactly.

583
00:42:46,220 --> 00:42:50,100
You don't want that happening
to your blood. It's bad news.

584
00:42:50,100 --> 00:42:51,700
And that's why, so far as you know,

585
00:42:51,700 --> 00:42:53,940
there isn't any liquid water
on Mars? Right.

586
00:42:53,940 --> 00:42:57,460
The atmosphere is so thin that if
there were any liquid water,

587
00:42:57,460 --> 00:42:59,020
it would just evaporate like that.

588
00:43:00,380 --> 00:43:03,220
So, suddenly, holding on to your
atmosphere becomes

589
00:43:03,220 --> 00:43:06,700
critical to keep your water
along with it, how do you do that?

590
00:43:06,700 --> 00:43:10,140
So you need the right combination
of things and one of them

591
00:43:10,140 --> 00:43:12,700
is the planet size
because that effects the gravity,

592
00:43:12,700 --> 00:43:16,140
and if you don't have enough gravity
then the atmosphere that was there

593
00:43:16,140 --> 00:43:18,820
will eventually go away.
And then, as the atmospheric

594
00:43:18,820 --> 00:43:21,660
pressure drops, then
the liquid water goes away.

595
00:43:21,660 --> 00:43:23,860
So there's this optimal size planet

596
00:43:23,860 --> 00:43:27,180
and Earth just happens to be
one of those, so you need all these

597
00:43:27,180 --> 00:43:30,220
things to line up just, you know,
shoot through the holes

598
00:43:30,220 --> 00:43:33,620
of the Swiss cheese in order to get
the right combination to have life.

599
00:43:33,620 --> 00:43:36,060
And no liquid water, no life?

600
00:43:36,060 --> 00:43:37,900
Yeah.

601
00:43:37,900 --> 00:43:40,540
Complicated things to build,
planets that you can live on,

602
00:43:40,540 --> 00:43:42,100
as it turns out.

603
00:43:48,380 --> 00:43:51,100
So there are a couple of things
to think about

604
00:43:51,100 --> 00:43:53,140
when positioning our planet.

605
00:43:55,180 --> 00:44:00,860
The best place to put our planet
for us is exactly where we are,

606
00:44:00,860 --> 00:44:04,940
93 million miles away from
the sun, third rock along,

607
00:44:04,940 --> 00:44:07,820
in the part of space that we've
called the "habitable zone",

608
00:44:07,820 --> 00:44:11,220
where we get just enough of a slug
of the sun's energy -

609
00:44:11,220 --> 00:44:13,060
not too much or too little.

610
00:44:16,460 --> 00:44:19,940
It's a zone where water doesn't
instantly freeze...

611
00:44:21,780 --> 00:44:24,380
..but also doesn't boil away.

612
00:44:31,140 --> 00:44:35,100
Both Earth and Mars
are in that zone.

613
00:44:40,220 --> 00:44:42,900
But even then,
as we've discovered with Mars,

614
00:44:42,900 --> 00:44:46,980
a planet has to be big enough
to hold on to its water

615
00:44:46,980 --> 00:44:50,820
with an atmosphere to stop it
escaping into space.

616
00:44:50,820 --> 00:44:53,860
So our planet has to be not
only in just the right place,

617
00:44:53,860 --> 00:44:57,540
it has to be just the right
size to support life.

618
00:45:08,540 --> 00:45:12,660
Where we place our planet needs
to be precisely right.

619
00:45:13,980 --> 00:45:18,700
It must go between Mars and Venus,

620
00:45:18,700 --> 00:45:21,300
bang in the middle
of the habitable zone.

621
00:45:22,940 --> 00:45:24,140
So there we are.

622
00:45:24,140 --> 00:45:27,780
All our planets in place
around what scientists call

623
00:45:27,780 --> 00:45:31,460
a middle-aged yellow dwarf -
our sun.

624
00:45:31,460 --> 00:45:34,700
We've built our solar system!
Wonderful.

625
00:45:42,460 --> 00:45:45,700
We started with a supernova...

626
00:45:52,740 --> 00:45:57,260
..which created light, and the
ingredients to make our sun.

627
00:46:02,140 --> 00:46:08,940
Then we made eight planets,
including one just like ours...

628
00:46:12,100 --> 00:46:14,380
..in the perfect place
to support life.

629
00:46:20,820 --> 00:46:23,260
Except that's not all.

630
00:46:23,260 --> 00:46:28,380
Can you imagine the Earth without
stars in the sky? Miserable.

631
00:46:28,380 --> 00:46:32,580
We need more than that one star,
we need a whole galaxy of them.

632
00:46:32,580 --> 00:46:35,860
Still, that's easy. Build one star,
you've built them all.

633
00:46:41,940 --> 00:46:45,380
We've made over 300 billion stars

634
00:46:45,380 --> 00:46:48,500
and put them all together
into a galaxy.

635
00:46:50,260 --> 00:46:53,100
Just like the one we live in,
the Milky Way.

636
00:46:55,740 --> 00:47:00,220
And we've put our sun with its
solar system right out here,

637
00:47:00,220 --> 00:47:03,460
in a sleepy backwater
on the outer edge.

638
00:47:06,700 --> 00:47:10,340
Astronomers have even given it
a galactic address.

639
00:47:10,340 --> 00:47:13,420
Seriously, anyone can reach us
at the local fluff,

640
00:47:13,420 --> 00:47:17,460
inside the local bubble at the Gould
Belt of the galaxy's Orion arm.

641
00:47:17,460 --> 00:47:19,340
I don't know what number.

642
00:47:19,340 --> 00:47:23,700
Anyway, it's a good job we are
out in the galactic sticks

643
00:47:23,700 --> 00:47:26,100
because we wouldn't want to make
the mistake of being

644
00:47:26,100 --> 00:47:27,820
too close to the centre of things.

645
00:47:32,940 --> 00:47:37,900
Because that is where lurks
a supermassive black hole.

646
00:47:37,900 --> 00:47:40,660
Yep, they really do exist.

647
00:47:40,660 --> 00:47:44,380
These are once-giant stars that have
collapsed in on themselves,

648
00:47:44,380 --> 00:47:47,980
pulling in millions of other stars
around them.

649
00:47:47,980 --> 00:47:50,380
They sit at the centre
of most galaxies,

650
00:47:50,380 --> 00:47:53,020
including our own Milky Way.

651
00:47:53,020 --> 00:47:55,060
Their gravity is so strong

652
00:47:55,060 --> 00:47:58,660
that not even light can escape
its violent pull.

653
00:48:02,620 --> 00:48:05,980
I think it's best
we stay well away from that.

654
00:48:05,980 --> 00:48:09,900
Where we are
is exactly where we want to be.

655
00:48:09,900 --> 00:48:12,940
This galactic neighbourhood
really works for us.

656
00:48:16,420 --> 00:48:19,820
But if we're building a universe,
we need more than one galaxy.

657
00:48:19,820 --> 00:48:23,100
We need a whole ocean of them.

658
00:48:23,100 --> 00:48:26,460
Some spiral, some spidery,
some lens-shaped,

659
00:48:26,460 --> 00:48:28,580
but each of them beautiful
and unique.

660
00:48:37,380 --> 00:48:40,980
And scientists have calculated
that, to fill our universe,

661
00:48:40,980 --> 00:48:46,260
we need more stars than grains
of sand on all the beaches on Earth.

662
00:48:52,980 --> 00:48:56,180
But all is not well
in the universe we've built.

663
00:49:03,940 --> 00:49:06,140
The galaxies are flying apart.

664
00:49:09,420 --> 00:49:12,060
I'm missing something
that holds them together.

665
00:49:15,700 --> 00:49:17,100
What have we forgotten?

666
00:49:23,540 --> 00:49:27,500
Our universe is missing
a vital ingredient.

667
00:49:27,500 --> 00:49:32,740
It's something that produces
a massive gravitational force.

668
00:49:32,740 --> 00:49:36,420
Without it,
the universe would disintegrate.

669
00:49:39,060 --> 00:49:43,100
Below my feet, is a lab full of
people, all trying to find

670
00:49:43,100 --> 00:49:45,980
the stuff that holds
the universe together.

671
00:49:45,980 --> 00:49:49,820
Which is why I'm heading
1.3km underground.

672
00:49:56,540 --> 00:50:00,580
Scientists have worked out that
what glues the galaxies together is

673
00:50:00,580 --> 00:50:03,980
the most common stuff there is.

674
00:50:09,940 --> 00:50:14,700
It makes up a staggering 85%
of everything.

675
00:50:17,060 --> 00:50:19,820
They named it "dark matter".

676
00:50:19,820 --> 00:50:24,860
Problem is, it's totally invisible
and undetectable.

677
00:50:26,380 --> 00:50:28,660
But that may be about to change,

678
00:50:28,660 --> 00:50:31,860
thanks to scientists
like Professor Rick Gaitskell.

679
00:50:33,500 --> 00:50:34,940
No music?

680
00:50:34,940 --> 00:50:38,780
Well, they did actually put
some in once upon a time. And?

681
00:50:38,780 --> 00:50:41,100
Nobody could agree on what to play!

682
00:50:41,100 --> 00:50:42,340
OK.

683
00:50:42,340 --> 00:50:46,300
We also had a light in here at one
point, it was all mod cons.

684
00:50:47,500 --> 00:50:49,900
Rick's built
a dark matter detector

685
00:50:49,900 --> 00:50:56,020
that's so sensitive he's had to
protect it under 1.3km of rock.

686
00:50:57,500 --> 00:50:59,900
Why have we stopped here?
I think this is it.

687
00:51:08,220 --> 00:51:11,100
These are scientists, not miners.

688
00:51:11,100 --> 00:51:12,860
I have a desperate urge to sing...

689
00:51:12,860 --> 00:51:15,780
SINGS: # Hi-ho, Hi-ho! #
I'm not going to.

690
00:51:15,780 --> 00:51:20,980
And they've spent $100 million
to look for something

691
00:51:20,980 --> 00:51:24,060
you can't see,

692
00:51:24,060 --> 00:51:25,740
you can't touch...

693
00:51:28,740 --> 00:51:30,620
..and we haven't even found.

694
00:51:38,100 --> 00:51:41,260
And this is what they've
spent their money on.

695
00:51:41,260 --> 00:51:43,300
So, is that it?

696
00:51:43,300 --> 00:51:46,180
Yep, that's the dark matter detector.
Or rather,

697
00:51:46,180 --> 00:51:50,260
this is the water tank that
surrounds our dark matter detector.

698
00:51:50,260 --> 00:51:53,740
I'm not being funny
but it's like being in my loft,

699
00:51:53,740 --> 00:51:55,980
except I bet there's no dead pigeons
in there,

700
00:51:55,980 --> 00:51:58,020
it's a pretty specialised
environment.

701
00:51:58,020 --> 00:52:00,020
It's got to be very clean.

702
00:52:00,020 --> 00:52:04,180
The water inside this tank is
extremely pure and it isolates our

703
00:52:04,180 --> 00:52:08,580
detector from all the radioactivity
in the rock, and even you.

704
00:52:08,580 --> 00:52:10,940
And in terms of search
instruments, this is

705
00:52:10,940 --> 00:52:13,020
one of the biggest in the world
or the best or...?

706
00:52:13,020 --> 00:52:15,780
This is the most sensitive dark
matter detector in the world

707
00:52:15,780 --> 00:52:18,500
and we're running it right now.
It's on? It's on.

708
00:52:26,820 --> 00:52:29,700
So, how does the detector work?

709
00:52:29,700 --> 00:52:33,740
Well, suspended inside it is a
capsule of a special gas

710
00:52:33,740 --> 00:52:34,900
called xenon.

711
00:52:36,580 --> 00:52:39,300
It's the same stuff
that's in this novelty toy.

712
00:52:43,940 --> 00:52:46,500
It's very nice,
it's a pleasing distraction,

713
00:52:46,500 --> 00:52:48,780
but why are you holding that thing?

714
00:52:48,780 --> 00:52:51,100
We've filled this plasma ball
with xenon

715
00:52:51,100 --> 00:52:54,100
and we're exciting it
using electricity.

716
00:52:54,100 --> 00:52:56,900
As you can see,
light is being generated.

717
00:52:56,900 --> 00:52:59,660
The dark matter detector
works on exactly the same principle.

718
00:52:59,660 --> 00:53:01,900
We filled it with xenon,

719
00:53:01,900 --> 00:53:05,700
and when a dark matter particle
comes in, the particle directly

720
00:53:05,700 --> 00:53:09,420
excites the atoms, and the atoms
emit light, which we then detect.

721
00:53:10,700 --> 00:53:13,620
So that's the event you're waiting
to observe. It's not a giant one of

722
00:53:13,620 --> 00:53:17,660
these, but that's to illustrate the
idea of seeing those interactions.

723
00:53:17,660 --> 00:53:20,460
That's right, and the particle events
we're looking for

724
00:53:20,460 --> 00:53:21,860
are extremely infrequent.

725
00:53:21,860 --> 00:53:25,940
We're operating this detector for
weeks, months, years,

726
00:53:25,940 --> 00:53:30,020
looking for very, very occasional
dark matter particles to

727
00:53:30,020 --> 00:53:32,860
interact with the xenon and we'll
see the light coming from it.

728
00:53:44,460 --> 00:53:47,340
It sounds complicated and it is.

729
00:53:47,340 --> 00:53:52,340
Rick's been searching for dark
matter particles for 23 years.

730
00:53:52,340 --> 00:53:56,180
But scientists know it must exist,

731
00:53:56,180 --> 00:53:59,060
because they can see the effects
of its gravity

732
00:53:59,060 --> 00:54:02,300
holding galaxies together.

733
00:54:02,300 --> 00:54:04,100
If they can detect it,

734
00:54:04,100 --> 00:54:07,780
they'll have solved one of the
greatest mysteries in science.

735
00:54:10,460 --> 00:54:15,100
Rick, would it ruin millions
of pounds' worth of research

736
00:54:15,100 --> 00:54:19,380
and years, decades in fact, of your
own work if I turn the lights on?

737
00:54:19,380 --> 00:54:24,020
Don't touch any one of those
buttons! That's six months' delay.

738
00:54:24,020 --> 00:54:26,420
I won't touch anything.
Hands in pockets.

739
00:54:27,940 --> 00:54:31,740
The first live results have
started streaming in.

740
00:54:31,740 --> 00:54:35,020
So, any of these spikes,
that spike, that could be it,

741
00:54:35,020 --> 00:54:37,820
one of greatest moments
in science ever?

742
00:54:37,820 --> 00:54:41,260
That spike could be it,
the event you're looking for?

743
00:54:41,260 --> 00:54:43,980
That's right. So, if that one was it,

744
00:54:43,980 --> 00:54:47,660
proof of the existence of dark
matter, and I'm here? Yep.

745
00:54:47,660 --> 00:54:48,860
Will I get my name on it?

746
00:54:48,860 --> 00:54:51,300
Well I was here.
If that's it, I was here just then.

747
00:54:51,300 --> 00:54:53,620
If it is that event,
we'll name it after you.

748
00:54:53,620 --> 00:54:58,020
Every day you enjoy your unusual
commute a mile under the ground.

749
00:54:59,460 --> 00:55:04,060
If that happens, if that's the day
that those spikes occur,

750
00:55:04,060 --> 00:55:06,100
it's a big deal!

751
00:55:06,100 --> 00:55:08,060
It will be an amazing feeling.

752
00:55:08,060 --> 00:55:10,140
I think you'll hear the celebration.

753
00:55:10,140 --> 00:55:14,740
Um, even though we're a mile
underground it will be quite a roar.

754
00:55:14,740 --> 00:55:17,260
I'll hear the champagne corks open!

755
00:55:20,100 --> 00:55:23,460
But I haven't got time to hang
around talking about champagne.

756
00:55:23,460 --> 00:55:25,740
I need to head back to the tower

757
00:55:25,740 --> 00:55:29,940
to add some elusive dark matter to
the cosmic mix right now.

758
00:55:42,340 --> 00:55:43,620
And it's working.

759
00:55:45,780 --> 00:55:50,780
The gravity of the dark matter is
pulling our galaxies back together.

760
00:55:56,660 --> 00:55:58,700
Disaster averted.

761
00:55:59,940 --> 00:56:02,980
Scientists have crunched all
the numbers relating to dark matter

762
00:56:02,980 --> 00:56:07,180
through a supercomputer and come
up with a way of seeing it.

763
00:56:07,180 --> 00:56:10,380
And for the first time, we can show
you what that looks like.

764
00:56:17,140 --> 00:56:22,460
Each of these points of light is a
galaxy made up of billions of stars.

765
00:56:25,460 --> 00:56:29,980
They are held together in a
vast gravitational web,

766
00:56:29,980 --> 00:56:32,820
created by ribbons of dark matter.

767
00:56:40,940 --> 00:56:44,220
Adding that missing matter to
a map of the universe

768
00:56:44,220 --> 00:56:47,660
means we can actually see
how we, here on our planet,

769
00:56:47,660 --> 00:56:51,500
really are connected to even
the remotest star.

770
00:56:51,500 --> 00:56:53,540
And it's...it's kind of beautiful.

771
00:57:03,740 --> 00:57:06,420
This vast web of dark matter...

772
00:57:08,380 --> 00:57:11,420
..holds the entire universe
together.

773
00:57:45,380 --> 00:57:50,420
As you look up on a clear night
at that band across the sky,

774
00:57:50,420 --> 00:57:54,900
you're looking into the heart
of the Milky Way -

775
00:57:54,900 --> 00:57:58,620
a tiny part of the great web
of galaxies.

776
00:58:01,380 --> 00:58:03,740
We are connected to it all

777
00:58:03,740 --> 00:58:06,260
because we are made
of the same stuff.

778
00:58:10,340 --> 00:58:13,180
And if anything had been a bit
different -

779
00:58:13,180 --> 00:58:15,660
the Earth a bit too small,

780
00:58:15,660 --> 00:58:18,580
the sun too bright,

781
00:58:18,580 --> 00:58:20,900
the other planets too big,

782
00:58:20,900 --> 00:58:25,020
or the solar system in the wrong
place in our galaxy...

783
00:58:28,420 --> 00:58:31,300
..then we simply wouldn't be here.

784
00:58:53,380 --> 00:58:56,380
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