Richard Hammond Builds a Planet s01e02 Episode Script
Richard Hammond Builds a Universe
Planet Earth.
Our home.
It's unique.
It has life.
But what's amazing, is none of it would exist without the sun, the moon and the stars around us.
We are connected to the universe in the most fundamental ways.
To find out how, I'm going to have to build my own.
I'm going to open up a cosmic tool-box and work it out.
And I'm going to build my universe up here, at the top of this impossibly high tower.
It gives us the perfect platform to make something really big.
Up here, we can do in seconds what it takes nature millions or billions of years to do.
And to build a universe, I'm going to need a lot of help.
I'll be honest, I'm faintly nervous.
Was that it? Wow! Beautiful! Ohh, this is really difficult! I told you, seventies' moves! There they are.
Like any construction project, there will be mistakes .
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but from those mistakes, we'll get real insights into what makes our universe exactly right for us to exist.
As an engineering challenge, this is about as big as it gets.
How many times have you marvelled at the stars? Depending upon your frame of mind, the stars might appear distant and magical, or cold and remote, but the fact is, we are all made of the same stuff.
And if you were to change anything about them, or about us, that connection, that delicate balance, would be lost.
And this isn't an idle fancy, a romantic notion, it's essential, elemental and real.
Without that connection, we wouldn't be here.
' And to understand how it works, we need to build a universe.
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.
And there are half a trillion galaxies in the universe.
So the job isn't really done until we build it all, from suns to galaxies.
I'm going to need to construct all of this up here, at the top of my tower, where there's loads of room.
To do this, we need to go back to the very start of everything.
We need to start from scratch.
In the case of our universe, the start of everything was 13.
8 billion years ago about.
I do like a challenge.
Most scientists agree that before the universe, there was nothing, nada.
But out of that nothing, was created something everything.
It all happened in an event called the big bang.
Thing is, the big bang is actually a misleading name for it because it wasn't a bang at all.
There is an analogy that scientists and boffins use to get their head round this event.
There's no explosion.
It wasn't a bang.
It's more like a balloon.
The big bang was a rapid expansion, just like inflating a balloon.
Now, of course, the universe expanded a lot quicker than our balloon.
Unimaginably so.
In a billionth of a second, it was already the size of our solar system.
But you take the point.
It's like a big expanding bubble of space.
But there's something even more bizarre about the big bang.
That universal expansion had no single point of origin.
It happened everywhere and all at the same time.
So one balloon isn't enough to demonstrate it.
I need countless balloons.
What's more, the expansion of the big bang is still happening today .
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which means that wherever I am, I'm at the very centre of an expanding universe.
And wherever you are, you, too, are at the centre of the universe.
So we've had our big bang, but there is a little problem.
It's dark.
There is no light after a big bang because there are no stars.
So, where can I get a star from? Well, fortunately, it turns out they make them just off the M40 near Oxford.
BUZZING AND BEEPING Inside this billion-pound chamber .
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we're going to squeeze, using colossal magnets, the only thing that was around after the big bang - hydrogen gas - until it ignites.
And that IS a star.
BUZZING AND BEEPING Sounds simple? It isn't.
Don't try this at home.
It is a job for the professionals.
The chamber will briefly use more power than a city like Birmingham.
And the ignition countdown begins 100m away, in the relative safety of mission control.
We're now approaching the T minus one minute mark.
T minus one minute.
I'm joining starmaker-in-chief, Professor Steve Cowley.
Steve, hello.
Hello.
I haven't touched anything and I promise not to because you're effectively creating a star here.
Yeah.
This looks AMAZING! This looks like I'd want it to look.
Is it running now? We're about to fire it up, and for a few seconds, we'll reach the temperature of round about 100 million degrees.
100 million degrees! What if it goes wrong, Steve? I mean, it's kind of extreme, isn't it? If something goes wrong, and it does do, the physicist in charge, she's got a red button, basically, and she will press the red button and it will abort the shot.
The amount of energy in there This isn't that far from my house is where I'm going! I live 50 miles away.
But it does have a wall that's 2m.
ALARM CLANGS What's that? It's the panic button.
You have to run now.
I'm not going to bother running.
Really, what would be the point? If something really did go wrong, you could cause a lot of damage.
Right.
And I'm being allowed to give the trigger command .
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to turn it on.
So, what I'm going to do now is trigger the creation of a star, briefly, on Earth.
Um CLEARS THROA Er, trigger, please.
Can you accelerate, please? OK.
Thank you.
INTERMITTENT BUZZING WHOOSHING COMPUTERISED VOICE: 'Start.
' It's starting up now.
Right.
Electrical current going through it.
I'll be honest, I'm faintly nervous.
How many times a day do you do this? '.
.
Eight, seven, six, five, four, 'three, two, one, zero.
' There it is.
Right.
Look at the instability, it's shaking.
This is mind-blowing.
Inside the chamber is hydrogen.
It was pretty much the only thing that existed in the darkness after the big bang.
This machine heats and squeezes the hydrogen with such force that it ignites, creating a star and light.
So, what's happening in that chamber right now, there, that isthat is a star on Earth.
What's remarkable is the process of making a star doesn't just create light.
It also makes brand-new ingredients, and this is going to help me build our universe.
There's little white specks, which is exactly what stars are doing.
It's turning hydrogen into helium.
They start with hydrogen and they make helium and then they get helium and they make carbon, then they make oxygen.
All the things you're made of, they are made bit by bit by bit in the centre of a star.
Was that it? That's it.
And was that the abort button there, you had all the Whoa Within a star, these different elements are made, but how do they then They've got to get elsewhere.
So, if it's a big enough star, it explodes - that's a supernova explosion - and it spews all that stuff, all those things you've made, all the carbon, all the iron, all the nickel, all the whatever, right, spews it out into the universe as dust, as particles, as this, that, and the other.
These elements are created within it and then - boom! - all over the universe.
Stars not only give us light, they are the element factories to build everything else.
Back at my tower, I can now make light, and create all the stuff to build the rest of our universe.
We just need a star to go supernova.
A supernova is the biggest explosion there is, and for us it's an essential stage in our construction process because it takes all those elements created in big stars and scatters them everywhere.
Just one note of caution though - when I say "big", I do mean "really, really big".
And that supernova has now scattered all the ingredients we need to build everything.
Floating around the tower, we've now got carbon, oxygen, iron .
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and all the other elements we're going to need to make the planets, and even us.
In that sense, everything really is stardust - you, me, everything you've ever seen or touched, or ever will.
All of it created from the birth and death of a star.
It's mind-blowing.
And that cloud of gas and dust, called a nebula, also provides the ingredients for other stars.
So we can now build our own star from it.
We'll call it the sun.
The real one took around 50 million years to form.
Here, we've done it in seconds.
And orbiting it is the dust and gas we'll need to make all the planets in our solar system.
The first planet to start forming is Jupiter.
But something's not going to plan.
The young planet is starting to hoover up way too much of the gas and rock.
And this process is slowing it down .
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causing it to fall inwards, towards the sun.
Which is a problem, because this is the very stuff that's going to build all the other planets.
It's bad.
What do we do to stop Jupiter gobbling up all our planetary building materials? Well, fortunately, I'm told there is a man who knows.
This is Professor Alexei Filippenko.
And THIS is a Fresnel lens.
A simple enough device, but surprisingly powerful.
Hi, Richard.
So, how do we get rid of our rampaging Jupiter problem? Oh, well, look.
Let me show you a demo that'll help illustrate it.
Declan, why don't you tilt it there? It's on fire.
Right away! It is on fire! But what's that got to do with Jupiter? It's a bit of wood? Yeah, well, what's happening is there's all these photons, all these little energetic particles of light coming from the sun and they're being focused here on this wood, heating it up, causing it to burn.
In the case of the early solar system, the sun was much brighter than it is now and it acted for hundreds of thousands, or millions of years, so the photons were hitting the particles of dust and gas and heating them up, causing the atoms to actually evaporate away, to be blown out of the solar system.
That meant that Jupiter was no longer slowing down and spiralling into the sun.
Two things.
One - there's a small fire over there.
Yeah! Two - all the stuff in the way of Jupiter, slowing it up, wasn't wood.
Yeah, I know, but look how powerful the sun is.
Here's a rock.
Why don't you put it right there.
I don't want to get zapped by your machine.
Declan won't zap you while you're putting it there.
And we need to have some safety glasses on because it's going to get heated up so much from the trillions of photons hitting it that, er, it's actually going to snap, crackle and pop.
Little pieces will come flying out.
You've got more safety than me.
Well, you know, my eyes are more important.
I'm an astronomer, OK? OK.
So let's put the rock in there I can't argue with that, can I? I can't argue with that.
I think you're OK.
CRACKING AND POPPING Oh, hang on, that is the rock.
Yeah, that's the rock flaking off because of all the energetic photons hitting it.
I am properly impressed with that.
That is in seconds.
It's heating up to 3,000 degrees Fahrenheit, OK? Now, over millions of years, the material is being blown out of the vicinity of Jupiter, so it's not growing any more and also it's not spiralling into the sun.
So that saves us.
Turn it off, Declan, I'm terrified.
So this is another one of those events that had to happen at the right time, in the right place, and to the right extent.
Too much of this for too long and there's nothing left to make your inner planets from.
Yeah, that's exactly right.
OK, a plan.
I'm going to use light from the sun to clear a path for Jupiter .
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to stop it slowing and spiralling inwards, gobbling all the building materials for our other planets.
So, let's crank up the light from our sun .
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and get those photons pumping.
Jupiter's way is now clear.
But luckily for us, the perfect amount of stuff is left behind to build the rest of our solar system.
So we've got Jupiter.
Now, how do we make our other planets? To find out what the planet formation was like in the early solar system, I need the help of the Texas Roller Derby.
Excuse me.
Sorry.
Course I do.
Sorry, ladies, excuse me.
Can I join? Oh! Do I really need that? You need it to protect your head.
Right.
Well, I'll pop it on.
Thank you.
What's your skate name? Your name on the track, your alter ego? Hamster.
Yeah, it's a long story.
What about Slamster? Slamster! Oh! I'm loving that! WOMEN: Yeah, that's good.
What sort of injuries can you acquire doing this? BOTH: Brokeneverything! Broken ankles.
Broken teeth.
Hands, arms I am really scared! You should be scared.
Now, I know what you're thinking.
Actually, I've no idea what you're thinking .
.
but bear with me.
This is a genuine scientific demonstration of what happened in the early solar system.
See you out there, girls.
Oh, scared! I should say, I'm not what you'd call a regular skater.
Imagine the sun in the centre of the track providing the gravity to pull around a whole host of rocks of different sizes.
These wannabe planets are known as planetesimals.
Some of these planetesimals were large, some very small, some moving in crazy orbits.
U-u-ugh! Yee-ugh! Whoo-uh! All of them were affected by one another's gravity.
So there were HUGE collisions.
Potential planets were flung out of the solar system.
And some wannabe planets were destroyed.
Others had huge chunks ripped off them.
What happened over just a few million years was a sort of planetary carnage.
Oh! This is really difficult! Ha-ha-ha Whoo-ooh! Eventually, some of the larger, more stable planets emerged and took the outside orbital lane.
Whilst closer to the sun, smaller planets jostled for position.
The remnants of this orbital tussle, the dead and never-to-be planets didn't just disappear, they still exist.
A graveyard of broken worlds now orbits the sun as a ring of debris known as the asteroid belt.
So here we are.
Our solar system.
There's Jupiter and, alongside it, the asteroid belt.
And then the rest of the planets in our solar system.
There's Mercury, nearest the sun.
Its atmosphere has already been burnt away.
Then Venus, a big bash early on has reversed its spin.
And Mars, there's an enormous volcano here .
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Olympus Mons, three times higher than Everest.
Then Jupiter, bigger than all the planets put together.
Saturn with its amazing rings.
So light, it could float on water.
Further out, Uranus, where summers last 21 Earth years, as do winters! And finally, Neptune.
Freezing cold with hurricane winds of 1,000 kilometres an hour.
Of course, there is one planet missing - ours.
And exactly where it goes is critical because we need it to support one very fragile thing - life.
Earth is unique amongst the planets in our solar system.
It teems with life.
Life which comes in countless different forms.
So what is it that makes Earth so special? What do we need for life to exist when we're building a solar system? To find out, these scientists are attempting to reach one of the most inhospitable and extreme places on Earth.
Sandro SHE SPEAKS ITALIAN How far is it to the lake? SHE CONTINUES IN ITALIAN Where they're heading is so toxic, it is like an alien planet.
If they can find life down there, it will help us understand the most basic requirements for life in our solar system.
OK, I'll follow you.
Be careful.
To get there, they must risk a perilous 3km descent into eastern Italy's Frasassi cave system.
Caves like these contain some of the last unexplored frontiers on Earth.
Here I come.
The expedition is led by astrobiologist Professor Jenn Macalady.
Stay left, it's really tight.
If you go to the right you are going to get stuck for sure.
I'm not far behind.
Use your feet.
Yes, I am, it's er tight.
Breathe out.
Yeah, that's it.
You got it? Yep.
You're through! Awesome.
The things I do for science! After six hours, they're approaching the final descent.
At the bottom, Jenn's hoping to shed light on the minimal conditions required for life.
Aldo, coming down.
OK! This is the Crystal Lake.
Wow, it's beautiful.
OK, I'm going down.
Deep below its surface is home to what Jenn is looking for.
It's a long way down, folks.
Down here, all the normal things you need to support life have disappeared.
Shall I come all the way down? There is no light.
No animals or plants to feed off.
And where they're going, there's no oxygen.
We made it.
The water is even poisonous but Jenn is hoping to find life there.
The hunt will involve one of the most dangerous dives on the planet.
Preparing to make the 80-foot plunge is ex-Navy diver Alejandro Crocetti.
Perfecto.
His dive time is strictly limited.
Any kind of cave diving is very dangerous, because if there's a problem, you can't just pop up to the surface.
You have a long way to go.
But also, in this particular case, the water is actually toxic.
So the chemicals that are dissolved in the water come through the skin, so that if you stay in that water for a while, then you become sick.
You start to have symptoms that prevent you from making good decisions.
Very quickly the passages become tighter and tighter.
There is no room to manoeuvre.
As soon as you move, you suspend all the sediment that's on the bottom and the visibility goes to zero very quickly.
Fish would die instantly here.
Very quickly the water will become sulphidic, more cloudy, more difficult to navigate through.
We're not meant to be there really.
It's a place where we can stay only for a few moments.
Finally, they find what they've been looking for.
These weird alien fingers are alive.
They are bacteria, living on nothing more than rock dissolved in toxic water.
Wow! Look at that, this is beautiful.
Were there a lot like this? Multi.
Multi? Si.
Amazing sample, bravo.
Grazie.
This is life that we don't really understand yet.
It's from water that's toxic, it's hostile, there's no oxygen.
Where we've lost all the light, almost nothing to live on.
All that's left really is water and rocks, and yet there's this beautiful form just full of interesting, weird, strange life, and it's extraordinary, because it represents something new that will help us explore for life on other planets.
One of the things that we can learn from a sample like this is that wherever we have rocks and water, then somehow the water is going to allow life to thrive because it allows things to mix.
It allows the rock to interact with life.
So water is really, as we understand life, the most essential ingredient.
Life as we know it can't exist without water but it must be liquid.
Water, of course, comes in several different states.
And where it is in our solar system is key.
Too close to our sun, and water boils away.
Too far away, like in the rings of Saturn .
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and water freezes as hard as iron.
Where we place our planet, then, is critical if we want to have liquid water.
But how much leeway do we have? What about here near Mars, about 142 million miles from the sun? Well, to find out if Mars is suitable for liquid water, and for life, first you've got to get there.
Mars.
And NASA's rover, driving on the surface.
Well, as close as you can get to its surface .
.
in Houston, Texas.
Don't look at the bulldozer, that gives away that it's not Mars.
Just so you know, that's not there! Or those cars.
It spoils the effect! And my guide is NASA astronaut, Mike Gernhardt.
Would it look anything like this? Yeah.
NASA wants to put humans on the Red Planet in the next 20 years.
Their goal is to find life.
Problem is, despite there being hundreds of old river beds on Mars, all images show that the liquid water has vanished from the surface.
So, what's happened to it? NASA is developing the kit to take us to the Red Planet to find out.
This is Building Nine.
A place I dreamt of as a kid .
.
and as an adult.
You do have the coolest garage in the world.
Yep, we got some really cool stuff.
This thing is called the Robonaut.
This is actually on the International Space Station at this point.
This is called the Space Exploration Vehicle.
This would be going to an asteroid, or possibly a moon of Mars like Phobos.
Then with the reaction-controlled jets, we can hop.
And an astronaut is on the end of a robot arm and we can have that on Mars, or the moon, or whatever planets we end up going to.
All of this really informs us how to support these deep space missions.
It's Talking to you is just like going through a movie plot, constantly, it's so Right, that all makes perfect senseif you're you.
RECORDING: 'We're now approaching the T minus one minute mark.
'T minus one minute.
T minus one minute.
' And this is how man might get to Mars - the Orion spaceship.
Are we getting in? We're going to get in.
Oh! I so want to get in.
A born astronaut, me.
Here I go! Right, climbing across.
You could bang your head on many things in here.
Ye-ow! Yeah.
Oh, yeah.
Ooh! Yeah, I am so in.
All right, good job! 'T minus 20 seconds and counting.
' 'Having been to space, Mike's going to take me 'through what a Mars launch would be like.
' So, you climb in here.
'Ten, nine' You're strapped in.
'Ignition sequence has started.
' Then there's check lists you go through.
'Five, four' The clock hits zero '.
.
two, one, zero' .
.
and, all of a sudden, you have this big thrust in your back.
And you're going up into space.
'And we have liftoff.
' We're going to be going faster than we ever have before so it's going to be a, you know, a real sporty ride.
Sporty, that's a good word.
Vigorous.
'Liftoff' So, four of us in here? Yep.
Mars.
Mars.
It's not a short trip, is it? It isn't.
Generally think of it as a nine-month trip out.
Nine months?! What if somebody snores? I snore.
I have actually flown in space with a guy that snored so loud that it kept me awake for days actually.
Were you not just tempted to, you know, let him out? Nah, you can't do that.
'OK, Houston, go in 30 seconds.
' INDISTINCT RESPONSE 'Mark one bravo.
' Having reached the Red Planet, we now need to get out and search for Mars's water.
So, I'll need one of these.
Can I just say, this is an amazing privilege to get to do this.
This is the Z1, next gen prototype.
Besides me, Bruce Willis is the only non-astronaut who's ever been cleared to wear a real spacesuit.
Oh, yeah.
It's kind of like putting on a big onesie.
Do I look faintly ridiculous? Ha-ha, yes! Wow! That's a glove and a half.
That is serious.
The NASA team are now putting me through a full Mars atmosphere suit simulation.
That's got to go all the way up until we get to four three, which is operating pressure.
OK.
Sound good? Yes.
OK I'm waiting for a massive burst of claustrophobia.
'The atmosphere on Mars is incredibly thin, just 1% of Earth's, 'so we need to pump up the suit, like inflating a tyre, 'to hold my body together.
' Swallowing.
You're looking worried.
Doing OK? I'm fine! Great.
You're starting to look more muscular now, you know.
No, I actually am, I'm actually flexing.
We're at three.
Three PSI.
Three PSI.
Four, one.
Four, one.
Popping ears.
We're at operating pressure.
Operating pressure.
Wow! So, the arms are a little bit long for you in the suit but that's as small as they go because you're at the small end This is like every shopping trip I've ever been on! The legs are a bit long on the jeans, sir, but that's the shortest we have.
All right! OK! Yeah, it's Why did I know it wasn't going to fit? So the next thing, we're going to release you from the donning stand.
I only have short legs, so the bigger steps thing MUSIC: "Stayin' Alive" The Bee Gees It had to happen.
I told you - seventies' moves, there they are.
I am super impressed.
My daughters will be just cringing, "Dad, don't dance!" I'm dancing, yeah.
See, look, girls, there it is.
Suddenly I feel like doing this a lot.
Oh, yeah, moonwalk! Were I on Mars right now, the atmosphere on the other side of this suit would be very different.
What's it like? Yeah, it's basically almost no atmosphere.
As we stand here, we're at 14.
7 pounds per square inch, on Mars the pressure is roughly ten torr, which is like one hundredth of this.
What would happen to me if I didn't have this? You'd be dead pretty soon.
You'd probably have a couple to three minutes, and then that would be it.
Clearly that's bad.
Well, thank heavens for this thing then.
'Mars is relatively close to Earth, 'yet we certainly couldn't live there.
'So, for life, what's wrong with the Red Planet?' Well, Mike's going to show us, with just a glass of water and a pump.
So that's a pump and you're just pumping the air out of here until, you're creating a vacuum in there.
Exactly.
It actually won't be a pure vacuum, it'll be the same pressure as we have on Mars, which is very low but not complete vacuum.
So you're just taking the air out to lower the pressure.
Exactly.
There it goes.
There it goes.
So there's no extra heat in there, that isn't at 100 degrees C? In fact that could be at zero degrees C.
This is why you should always be careful with your spacesuit on Mars.
Exactly.
You don't want that happening to your blood.
It's bad news.
And that's why, so far as you know, there isn't any liquid water on Mars? Right.
The atmosphere is so thin that if there were any liquid water, it would just evaporate like that.
So, suddenly, holding on to your atmosphere becomes critical to keep your water along with it, how do you do that? So you need the right combination of things and one of them is the planet size because that effects the gravity, and if you don't have enough gravity then the atmosphere that was there will eventually go away.
And then, as the atmospheric pressure drops, then the liquid water goes away.
So there's this optimal size planet and Earth just happens to be one of those, so you need all these things to line up just, you know, shoot through the holes of the Swiss cheese in order to get the right combination to have life.
And no liquid water, no life? Yeah.
Complicated things to build, planets that you can live on, as it turns out.
So there are a couple of things to think about when positioning our planet.
The best place to put our planet for us is exactly where we are, 93 million miles away from the sun, third rock along, in the part of space that we've called the "habitable zone", where we get just enough of a slug of the sun's energy - not too much or too little.
It's a zone where water doesn't instantly freeze .
.
but also doesn't boil away.
Both Earth and Mars are in that zone.
But even then, as we've discovered with Mars, a planet has to be big enough to hold on to its water with an atmosphere to stop it escaping into space.
So our planet has to be not only in just the right place, it has to be just the right size to support life.
Where we place our planet needs to be precisely right.
It must go between Mars and Venus, bang in the middle of the habitable zone.
So there we are.
All our planets in place around what scientists call a middle-aged yellow dwarf - our sun.
We've built our solar system! Wonderful.
We started with a supernova .
.
which created light, and the ingredients to make our sun.
Then we made eight planets, including one just like ours .
.
in the perfect place to support life.
Except that's not all.
Can you imagine the Earth without stars in the sky? Miserable.
We need more than that one star, we need a whole galaxy of them.
Still, that's easy.
Build one star, you've built them all.
We've made over 300 billion stars and put them all together into a galaxy.
Just like the one we live in, the Milky Way.
And we've put our sun with its solar system right out here, in a sleepy backwater on the outer edge.
Astronomers have even given it a galactic address.
Seriously, anyone can reach us at the local fluff, inside the local bubble at the Gould Belt of the galaxy's Orion arm.
I don't know what number.
Anyway, it's a good job we are out in the galactic sticks because we wouldn't want to make the mistake of being too close to the centre of things.
Because that is where lurks a supermassive black hole.
Yep, they really do exist.
These are once-giant stars that have collapsed in on themselves, pulling in millions of other stars around them.
They sit at the centre of most galaxies, including our own Milky Way.
Their gravity is so strong that not even light can escape its violent pull.
I think it's best we stay well away from that.
Where we are is exactly where we want to be.
This galactic neighbourhood really works for us.
But if we're building a universe, we need more than one galaxy.
We need a whole ocean of them.
Some spiral, some spidery, some lens-shaped, but each of them beautiful and unique.
And scientists have calculated that, to fill our universe, we need more stars than grains of sand on all the beaches on Earth.
But all is not well in the universe we've built.
The galaxies are flying apart.
I'm missing something that holds them together.
What have we forgotten? Our universe is missing a vital ingredient.
It's something that produces a massive gravitational force.
Without it, the universe would disintegrate.
Below my feet, is a lab full of people, all trying to find the stuff that holds the universe together.
Which is why I'm heading 1.
3km underground.
Scientists have worked out that what glues the galaxies together is the most common stuff there is.
It makes up a staggering 85% of everything.
They named it "dark matter".
Problem is, it's totally invisible and undetectable.
But that may be about to change, thanks to scientists like Professor Rick Gaitskell.
No music? Well, they did actually put some in once upon a time.
And? Nobody could agree on what to play! OK.
We also had a light in here at one point, it was all mod cons.
Rick's built a dark matter detector that's so sensitive he's had to protect it under 1.
3km of rock.
Why have we stopped here? I think this is it.
These are scientists, not miners.
I have a desperate urge to sing SINGS: # Hi-ho, Hi-ho! # I'm not going to.
And they've spent $100 million to look for something you can't see, you can't touch .
.
and we haven't even found.
And this is what they've spent their money on.
So, is that it? Yep, that's the dark matter detector.
Or rather, this is the water tank that surrounds our dark matter detector.
I'm not being funny but it's like being in my loft, except I bet there's no dead pigeons in there, it's a pretty specialised environment.
It's got to be very clean.
The water inside this tank is extremely pure and it isolates our detector from all the radioactivity in the rock, and even you.
And in terms of search instruments, this is one of the biggest in the world or the best or? This is the most sensitive dark matter detector in the world and we're running it right now.
It's on? It's on.
So, how does the detector work? Well, suspended inside it is a capsule of a special gas called xenon.
It's the same stuff that's in this novelty toy.
It's very nice, it's a pleasing distraction, but why are you holding that thing? We've filled this plasma ball with xenon and we're exciting it using electricity.
As you can see, light is being generated.
The dark matter detector works on exactly the same principle.
We filled it with xenon, and when a dark matter particle comes in, the particle directly excites the atoms, and the atoms emit light, which we then detect.
So that's the event you're waiting to observe.
It's not a giant one of these, but that's to illustrate the idea of seeing those interactions.
That's right, and the particle events we're looking for are extremely infrequent.
We're operating this detector for weeks, months, years, looking for very, very occasional dark matter particles to interact with the xenon and we'll see the light coming from it.
It sounds complicated and it is.
Rick's been searching for dark matter particles for 23 years.
But scientists know it must exist, because they can see the effects of its gravity holding galaxies together.
If they can detect it, they'll have solved one of the greatest mysteries in science.
Rick, would it ruin millions of pounds' worth of research and years, decades in fact, of your own work if I turn the lights on? Don't touch any one of those buttons! That's six months' delay.
I won't touch anything.
Hands in pockets.
The first live results have started streaming in.
So, any of these spikes, that spike, that could be it, one of greatest moments in science ever? That spike could be it, the event you're looking for? That's right.
So, if that one was it, proof of the existence of dark matter, and I'm here? Yep.
Will I get my name on it? Well I was here.
If that's it, I was here just then.
If it is that event, we'll name it after you.
Every day you enjoy your unusual commute a mile under the ground.
If that happens, if that's the day that those spikes occur, it's a big deal! It will be an amazing feeling.
I think you'll hear the celebration.
Um, even though we're a mile underground it will be quite a roar.
I'll hear the champagne corks open! But I haven't got time to hang around talking about champagne.
I need to head back to the tower to add some elusive dark matter to the cosmic mix right now.
And it's working.
The gravity of the dark matter is pulling our galaxies back together.
Disaster averted.
Scientists have crunched all the numbers relating to dark matter through a supercomputer and come up with a way of seeing it.
And for the first time, we can show you what that looks like.
Each of these points of light is a galaxy made up of billions of stars.
They are held together in a vast gravitational web, created by ribbons of dark matter.
Adding that missing matter to a map of the universe means we can actually see how we, here on our planet, really are connected to even the remotest star.
And it'sit's kind of beautiful.
This vast web of dark matter .
.
holds the entire universe together.
As you look up on a clear night at that band across the sky, you're looking into the heart of the Milky Way - a tiny part of the great web of galaxies.
We are connected to it all because we are made of the same stuff.
And if anything had been a bit different - the Earth a bit too small, the sun too bright, the other planets too big, or the solar system in the wrong place in our galaxy .
.
then we simply wouldn't be here.
Our home.
It's unique.
It has life.
But what's amazing, is none of it would exist without the sun, the moon and the stars around us.
We are connected to the universe in the most fundamental ways.
To find out how, I'm going to have to build my own.
I'm going to open up a cosmic tool-box and work it out.
And I'm going to build my universe up here, at the top of this impossibly high tower.
It gives us the perfect platform to make something really big.
Up here, we can do in seconds what it takes nature millions or billions of years to do.
And to build a universe, I'm going to need a lot of help.
I'll be honest, I'm faintly nervous.
Was that it? Wow! Beautiful! Ohh, this is really difficult! I told you, seventies' moves! There they are.
Like any construction project, there will be mistakes .
.
but from those mistakes, we'll get real insights into what makes our universe exactly right for us to exist.
As an engineering challenge, this is about as big as it gets.
How many times have you marvelled at the stars? Depending upon your frame of mind, the stars might appear distant and magical, or cold and remote, but the fact is, we are all made of the same stuff.
And if you were to change anything about them, or about us, that connection, that delicate balance, would be lost.
And this isn't an idle fancy, a romantic notion, it's essential, elemental and real.
Without that connection, we wouldn't be here.
' And to understand how it works, we need to build a universe.
It's not a small task .
.
because Earth is in a solar system .
.
which is in just one tiny part of a galaxy .
.
that has over 300 billion stars within it.
And there are half a trillion galaxies in the universe.
So the job isn't really done until we build it all, from suns to galaxies.
I'm going to need to construct all of this up here, at the top of my tower, where there's loads of room.
To do this, we need to go back to the very start of everything.
We need to start from scratch.
In the case of our universe, the start of everything was 13.
8 billion years ago about.
I do like a challenge.
Most scientists agree that before the universe, there was nothing, nada.
But out of that nothing, was created something everything.
It all happened in an event called the big bang.
Thing is, the big bang is actually a misleading name for it because it wasn't a bang at all.
There is an analogy that scientists and boffins use to get their head round this event.
There's no explosion.
It wasn't a bang.
It's more like a balloon.
The big bang was a rapid expansion, just like inflating a balloon.
Now, of course, the universe expanded a lot quicker than our balloon.
Unimaginably so.
In a billionth of a second, it was already the size of our solar system.
But you take the point.
It's like a big expanding bubble of space.
But there's something even more bizarre about the big bang.
That universal expansion had no single point of origin.
It happened everywhere and all at the same time.
So one balloon isn't enough to demonstrate it.
I need countless balloons.
What's more, the expansion of the big bang is still happening today .
.
which means that wherever I am, I'm at the very centre of an expanding universe.
And wherever you are, you, too, are at the centre of the universe.
So we've had our big bang, but there is a little problem.
It's dark.
There is no light after a big bang because there are no stars.
So, where can I get a star from? Well, fortunately, it turns out they make them just off the M40 near Oxford.
BUZZING AND BEEPING Inside this billion-pound chamber .
.
we're going to squeeze, using colossal magnets, the only thing that was around after the big bang - hydrogen gas - until it ignites.
And that IS a star.
BUZZING AND BEEPING Sounds simple? It isn't.
Don't try this at home.
It is a job for the professionals.
The chamber will briefly use more power than a city like Birmingham.
And the ignition countdown begins 100m away, in the relative safety of mission control.
We're now approaching the T minus one minute mark.
T minus one minute.
I'm joining starmaker-in-chief, Professor Steve Cowley.
Steve, hello.
Hello.
I haven't touched anything and I promise not to because you're effectively creating a star here.
Yeah.
This looks AMAZING! This looks like I'd want it to look.
Is it running now? We're about to fire it up, and for a few seconds, we'll reach the temperature of round about 100 million degrees.
100 million degrees! What if it goes wrong, Steve? I mean, it's kind of extreme, isn't it? If something goes wrong, and it does do, the physicist in charge, she's got a red button, basically, and she will press the red button and it will abort the shot.
The amount of energy in there This isn't that far from my house is where I'm going! I live 50 miles away.
But it does have a wall that's 2m.
ALARM CLANGS What's that? It's the panic button.
You have to run now.
I'm not going to bother running.
Really, what would be the point? If something really did go wrong, you could cause a lot of damage.
Right.
And I'm being allowed to give the trigger command .
.
to turn it on.
So, what I'm going to do now is trigger the creation of a star, briefly, on Earth.
Um CLEARS THROA Er, trigger, please.
Can you accelerate, please? OK.
Thank you.
INTERMITTENT BUZZING WHOOSHING COMPUTERISED VOICE: 'Start.
' It's starting up now.
Right.
Electrical current going through it.
I'll be honest, I'm faintly nervous.
How many times a day do you do this? '.
.
Eight, seven, six, five, four, 'three, two, one, zero.
' There it is.
Right.
Look at the instability, it's shaking.
This is mind-blowing.
Inside the chamber is hydrogen.
It was pretty much the only thing that existed in the darkness after the big bang.
This machine heats and squeezes the hydrogen with such force that it ignites, creating a star and light.
So, what's happening in that chamber right now, there, that isthat is a star on Earth.
What's remarkable is the process of making a star doesn't just create light.
It also makes brand-new ingredients, and this is going to help me build our universe.
There's little white specks, which is exactly what stars are doing.
It's turning hydrogen into helium.
They start with hydrogen and they make helium and then they get helium and they make carbon, then they make oxygen.
All the things you're made of, they are made bit by bit by bit in the centre of a star.
Was that it? That's it.
And was that the abort button there, you had all the Whoa Within a star, these different elements are made, but how do they then They've got to get elsewhere.
So, if it's a big enough star, it explodes - that's a supernova explosion - and it spews all that stuff, all those things you've made, all the carbon, all the iron, all the nickel, all the whatever, right, spews it out into the universe as dust, as particles, as this, that, and the other.
These elements are created within it and then - boom! - all over the universe.
Stars not only give us light, they are the element factories to build everything else.
Back at my tower, I can now make light, and create all the stuff to build the rest of our universe.
We just need a star to go supernova.
A supernova is the biggest explosion there is, and for us it's an essential stage in our construction process because it takes all those elements created in big stars and scatters them everywhere.
Just one note of caution though - when I say "big", I do mean "really, really big".
And that supernova has now scattered all the ingredients we need to build everything.
Floating around the tower, we've now got carbon, oxygen, iron .
.
and all the other elements we're going to need to make the planets, and even us.
In that sense, everything really is stardust - you, me, everything you've ever seen or touched, or ever will.
All of it created from the birth and death of a star.
It's mind-blowing.
And that cloud of gas and dust, called a nebula, also provides the ingredients for other stars.
So we can now build our own star from it.
We'll call it the sun.
The real one took around 50 million years to form.
Here, we've done it in seconds.
And orbiting it is the dust and gas we'll need to make all the planets in our solar system.
The first planet to start forming is Jupiter.
But something's not going to plan.
The young planet is starting to hoover up way too much of the gas and rock.
And this process is slowing it down .
.
causing it to fall inwards, towards the sun.
Which is a problem, because this is the very stuff that's going to build all the other planets.
It's bad.
What do we do to stop Jupiter gobbling up all our planetary building materials? Well, fortunately, I'm told there is a man who knows.
This is Professor Alexei Filippenko.
And THIS is a Fresnel lens.
A simple enough device, but surprisingly powerful.
Hi, Richard.
So, how do we get rid of our rampaging Jupiter problem? Oh, well, look.
Let me show you a demo that'll help illustrate it.
Declan, why don't you tilt it there? It's on fire.
Right away! It is on fire! But what's that got to do with Jupiter? It's a bit of wood? Yeah, well, what's happening is there's all these photons, all these little energetic particles of light coming from the sun and they're being focused here on this wood, heating it up, causing it to burn.
In the case of the early solar system, the sun was much brighter than it is now and it acted for hundreds of thousands, or millions of years, so the photons were hitting the particles of dust and gas and heating them up, causing the atoms to actually evaporate away, to be blown out of the solar system.
That meant that Jupiter was no longer slowing down and spiralling into the sun.
Two things.
One - there's a small fire over there.
Yeah! Two - all the stuff in the way of Jupiter, slowing it up, wasn't wood.
Yeah, I know, but look how powerful the sun is.
Here's a rock.
Why don't you put it right there.
I don't want to get zapped by your machine.
Declan won't zap you while you're putting it there.
And we need to have some safety glasses on because it's going to get heated up so much from the trillions of photons hitting it that, er, it's actually going to snap, crackle and pop.
Little pieces will come flying out.
You've got more safety than me.
Well, you know, my eyes are more important.
I'm an astronomer, OK? OK.
So let's put the rock in there I can't argue with that, can I? I can't argue with that.
I think you're OK.
CRACKING AND POPPING Oh, hang on, that is the rock.
Yeah, that's the rock flaking off because of all the energetic photons hitting it.
I am properly impressed with that.
That is in seconds.
It's heating up to 3,000 degrees Fahrenheit, OK? Now, over millions of years, the material is being blown out of the vicinity of Jupiter, so it's not growing any more and also it's not spiralling into the sun.
So that saves us.
Turn it off, Declan, I'm terrified.
So this is another one of those events that had to happen at the right time, in the right place, and to the right extent.
Too much of this for too long and there's nothing left to make your inner planets from.
Yeah, that's exactly right.
OK, a plan.
I'm going to use light from the sun to clear a path for Jupiter .
.
to stop it slowing and spiralling inwards, gobbling all the building materials for our other planets.
So, let's crank up the light from our sun .
.
and get those photons pumping.
Jupiter's way is now clear.
But luckily for us, the perfect amount of stuff is left behind to build the rest of our solar system.
So we've got Jupiter.
Now, how do we make our other planets? To find out what the planet formation was like in the early solar system, I need the help of the Texas Roller Derby.
Excuse me.
Sorry.
Course I do.
Sorry, ladies, excuse me.
Can I join? Oh! Do I really need that? You need it to protect your head.
Right.
Well, I'll pop it on.
Thank you.
What's your skate name? Your name on the track, your alter ego? Hamster.
Yeah, it's a long story.
What about Slamster? Slamster! Oh! I'm loving that! WOMEN: Yeah, that's good.
What sort of injuries can you acquire doing this? BOTH: Brokeneverything! Broken ankles.
Broken teeth.
Hands, arms I am really scared! You should be scared.
Now, I know what you're thinking.
Actually, I've no idea what you're thinking .
.
but bear with me.
This is a genuine scientific demonstration of what happened in the early solar system.
See you out there, girls.
Oh, scared! I should say, I'm not what you'd call a regular skater.
Imagine the sun in the centre of the track providing the gravity to pull around a whole host of rocks of different sizes.
These wannabe planets are known as planetesimals.
Some of these planetesimals were large, some very small, some moving in crazy orbits.
U-u-ugh! Yee-ugh! Whoo-uh! All of them were affected by one another's gravity.
So there were HUGE collisions.
Potential planets were flung out of the solar system.
And some wannabe planets were destroyed.
Others had huge chunks ripped off them.
What happened over just a few million years was a sort of planetary carnage.
Oh! This is really difficult! Ha-ha-ha Whoo-ooh! Eventually, some of the larger, more stable planets emerged and took the outside orbital lane.
Whilst closer to the sun, smaller planets jostled for position.
The remnants of this orbital tussle, the dead and never-to-be planets didn't just disappear, they still exist.
A graveyard of broken worlds now orbits the sun as a ring of debris known as the asteroid belt.
So here we are.
Our solar system.
There's Jupiter and, alongside it, the asteroid belt.
And then the rest of the planets in our solar system.
There's Mercury, nearest the sun.
Its atmosphere has already been burnt away.
Then Venus, a big bash early on has reversed its spin.
And Mars, there's an enormous volcano here .
.
Olympus Mons, three times higher than Everest.
Then Jupiter, bigger than all the planets put together.
Saturn with its amazing rings.
So light, it could float on water.
Further out, Uranus, where summers last 21 Earth years, as do winters! And finally, Neptune.
Freezing cold with hurricane winds of 1,000 kilometres an hour.
Of course, there is one planet missing - ours.
And exactly where it goes is critical because we need it to support one very fragile thing - life.
Earth is unique amongst the planets in our solar system.
It teems with life.
Life which comes in countless different forms.
So what is it that makes Earth so special? What do we need for life to exist when we're building a solar system? To find out, these scientists are attempting to reach one of the most inhospitable and extreme places on Earth.
Sandro SHE SPEAKS ITALIAN How far is it to the lake? SHE CONTINUES IN ITALIAN Where they're heading is so toxic, it is like an alien planet.
If they can find life down there, it will help us understand the most basic requirements for life in our solar system.
OK, I'll follow you.
Be careful.
To get there, they must risk a perilous 3km descent into eastern Italy's Frasassi cave system.
Caves like these contain some of the last unexplored frontiers on Earth.
Here I come.
The expedition is led by astrobiologist Professor Jenn Macalady.
Stay left, it's really tight.
If you go to the right you are going to get stuck for sure.
I'm not far behind.
Use your feet.
Yes, I am, it's er tight.
Breathe out.
Yeah, that's it.
You got it? Yep.
You're through! Awesome.
The things I do for science! After six hours, they're approaching the final descent.
At the bottom, Jenn's hoping to shed light on the minimal conditions required for life.
Aldo, coming down.
OK! This is the Crystal Lake.
Wow, it's beautiful.
OK, I'm going down.
Deep below its surface is home to what Jenn is looking for.
It's a long way down, folks.
Down here, all the normal things you need to support life have disappeared.
Shall I come all the way down? There is no light.
No animals or plants to feed off.
And where they're going, there's no oxygen.
We made it.
The water is even poisonous but Jenn is hoping to find life there.
The hunt will involve one of the most dangerous dives on the planet.
Preparing to make the 80-foot plunge is ex-Navy diver Alejandro Crocetti.
Perfecto.
His dive time is strictly limited.
Any kind of cave diving is very dangerous, because if there's a problem, you can't just pop up to the surface.
You have a long way to go.
But also, in this particular case, the water is actually toxic.
So the chemicals that are dissolved in the water come through the skin, so that if you stay in that water for a while, then you become sick.
You start to have symptoms that prevent you from making good decisions.
Very quickly the passages become tighter and tighter.
There is no room to manoeuvre.
As soon as you move, you suspend all the sediment that's on the bottom and the visibility goes to zero very quickly.
Fish would die instantly here.
Very quickly the water will become sulphidic, more cloudy, more difficult to navigate through.
We're not meant to be there really.
It's a place where we can stay only for a few moments.
Finally, they find what they've been looking for.
These weird alien fingers are alive.
They are bacteria, living on nothing more than rock dissolved in toxic water.
Wow! Look at that, this is beautiful.
Were there a lot like this? Multi.
Multi? Si.
Amazing sample, bravo.
Grazie.
This is life that we don't really understand yet.
It's from water that's toxic, it's hostile, there's no oxygen.
Where we've lost all the light, almost nothing to live on.
All that's left really is water and rocks, and yet there's this beautiful form just full of interesting, weird, strange life, and it's extraordinary, because it represents something new that will help us explore for life on other planets.
One of the things that we can learn from a sample like this is that wherever we have rocks and water, then somehow the water is going to allow life to thrive because it allows things to mix.
It allows the rock to interact with life.
So water is really, as we understand life, the most essential ingredient.
Life as we know it can't exist without water but it must be liquid.
Water, of course, comes in several different states.
And where it is in our solar system is key.
Too close to our sun, and water boils away.
Too far away, like in the rings of Saturn .
.
and water freezes as hard as iron.
Where we place our planet, then, is critical if we want to have liquid water.
But how much leeway do we have? What about here near Mars, about 142 million miles from the sun? Well, to find out if Mars is suitable for liquid water, and for life, first you've got to get there.
Mars.
And NASA's rover, driving on the surface.
Well, as close as you can get to its surface .
.
in Houston, Texas.
Don't look at the bulldozer, that gives away that it's not Mars.
Just so you know, that's not there! Or those cars.
It spoils the effect! And my guide is NASA astronaut, Mike Gernhardt.
Would it look anything like this? Yeah.
NASA wants to put humans on the Red Planet in the next 20 years.
Their goal is to find life.
Problem is, despite there being hundreds of old river beds on Mars, all images show that the liquid water has vanished from the surface.
So, what's happened to it? NASA is developing the kit to take us to the Red Planet to find out.
This is Building Nine.
A place I dreamt of as a kid .
.
and as an adult.
You do have the coolest garage in the world.
Yep, we got some really cool stuff.
This thing is called the Robonaut.
This is actually on the International Space Station at this point.
This is called the Space Exploration Vehicle.
This would be going to an asteroid, or possibly a moon of Mars like Phobos.
Then with the reaction-controlled jets, we can hop.
And an astronaut is on the end of a robot arm and we can have that on Mars, or the moon, or whatever planets we end up going to.
All of this really informs us how to support these deep space missions.
It's Talking to you is just like going through a movie plot, constantly, it's so Right, that all makes perfect senseif you're you.
RECORDING: 'We're now approaching the T minus one minute mark.
'T minus one minute.
T minus one minute.
' And this is how man might get to Mars - the Orion spaceship.
Are we getting in? We're going to get in.
Oh! I so want to get in.
A born astronaut, me.
Here I go! Right, climbing across.
You could bang your head on many things in here.
Ye-ow! Yeah.
Oh, yeah.
Ooh! Yeah, I am so in.
All right, good job! 'T minus 20 seconds and counting.
' 'Having been to space, Mike's going to take me 'through what a Mars launch would be like.
' So, you climb in here.
'Ten, nine' You're strapped in.
'Ignition sequence has started.
' Then there's check lists you go through.
'Five, four' The clock hits zero '.
.
two, one, zero' .
.
and, all of a sudden, you have this big thrust in your back.
And you're going up into space.
'And we have liftoff.
' We're going to be going faster than we ever have before so it's going to be a, you know, a real sporty ride.
Sporty, that's a good word.
Vigorous.
'Liftoff' So, four of us in here? Yep.
Mars.
Mars.
It's not a short trip, is it? It isn't.
Generally think of it as a nine-month trip out.
Nine months?! What if somebody snores? I snore.
I have actually flown in space with a guy that snored so loud that it kept me awake for days actually.
Were you not just tempted to, you know, let him out? Nah, you can't do that.
'OK, Houston, go in 30 seconds.
' INDISTINCT RESPONSE 'Mark one bravo.
' Having reached the Red Planet, we now need to get out and search for Mars's water.
So, I'll need one of these.
Can I just say, this is an amazing privilege to get to do this.
This is the Z1, next gen prototype.
Besides me, Bruce Willis is the only non-astronaut who's ever been cleared to wear a real spacesuit.
Oh, yeah.
It's kind of like putting on a big onesie.
Do I look faintly ridiculous? Ha-ha, yes! Wow! That's a glove and a half.
That is serious.
The NASA team are now putting me through a full Mars atmosphere suit simulation.
That's got to go all the way up until we get to four three, which is operating pressure.
OK.
Sound good? Yes.
OK I'm waiting for a massive burst of claustrophobia.
'The atmosphere on Mars is incredibly thin, just 1% of Earth's, 'so we need to pump up the suit, like inflating a tyre, 'to hold my body together.
' Swallowing.
You're looking worried.
Doing OK? I'm fine! Great.
You're starting to look more muscular now, you know.
No, I actually am, I'm actually flexing.
We're at three.
Three PSI.
Three PSI.
Four, one.
Four, one.
Popping ears.
We're at operating pressure.
Operating pressure.
Wow! So, the arms are a little bit long for you in the suit but that's as small as they go because you're at the small end This is like every shopping trip I've ever been on! The legs are a bit long on the jeans, sir, but that's the shortest we have.
All right! OK! Yeah, it's Why did I know it wasn't going to fit? So the next thing, we're going to release you from the donning stand.
I only have short legs, so the bigger steps thing MUSIC: "Stayin' Alive" The Bee Gees It had to happen.
I told you - seventies' moves, there they are.
I am super impressed.
My daughters will be just cringing, "Dad, don't dance!" I'm dancing, yeah.
See, look, girls, there it is.
Suddenly I feel like doing this a lot.
Oh, yeah, moonwalk! Were I on Mars right now, the atmosphere on the other side of this suit would be very different.
What's it like? Yeah, it's basically almost no atmosphere.
As we stand here, we're at 14.
7 pounds per square inch, on Mars the pressure is roughly ten torr, which is like one hundredth of this.
What would happen to me if I didn't have this? You'd be dead pretty soon.
You'd probably have a couple to three minutes, and then that would be it.
Clearly that's bad.
Well, thank heavens for this thing then.
'Mars is relatively close to Earth, 'yet we certainly couldn't live there.
'So, for life, what's wrong with the Red Planet?' Well, Mike's going to show us, with just a glass of water and a pump.
So that's a pump and you're just pumping the air out of here until, you're creating a vacuum in there.
Exactly.
It actually won't be a pure vacuum, it'll be the same pressure as we have on Mars, which is very low but not complete vacuum.
So you're just taking the air out to lower the pressure.
Exactly.
There it goes.
There it goes.
So there's no extra heat in there, that isn't at 100 degrees C? In fact that could be at zero degrees C.
This is why you should always be careful with your spacesuit on Mars.
Exactly.
You don't want that happening to your blood.
It's bad news.
And that's why, so far as you know, there isn't any liquid water on Mars? Right.
The atmosphere is so thin that if there were any liquid water, it would just evaporate like that.
So, suddenly, holding on to your atmosphere becomes critical to keep your water along with it, how do you do that? So you need the right combination of things and one of them is the planet size because that effects the gravity, and if you don't have enough gravity then the atmosphere that was there will eventually go away.
And then, as the atmospheric pressure drops, then the liquid water goes away.
So there's this optimal size planet and Earth just happens to be one of those, so you need all these things to line up just, you know, shoot through the holes of the Swiss cheese in order to get the right combination to have life.
And no liquid water, no life? Yeah.
Complicated things to build, planets that you can live on, as it turns out.
So there are a couple of things to think about when positioning our planet.
The best place to put our planet for us is exactly where we are, 93 million miles away from the sun, third rock along, in the part of space that we've called the "habitable zone", where we get just enough of a slug of the sun's energy - not too much or too little.
It's a zone where water doesn't instantly freeze .
.
but also doesn't boil away.
Both Earth and Mars are in that zone.
But even then, as we've discovered with Mars, a planet has to be big enough to hold on to its water with an atmosphere to stop it escaping into space.
So our planet has to be not only in just the right place, it has to be just the right size to support life.
Where we place our planet needs to be precisely right.
It must go between Mars and Venus, bang in the middle of the habitable zone.
So there we are.
All our planets in place around what scientists call a middle-aged yellow dwarf - our sun.
We've built our solar system! Wonderful.
We started with a supernova .
.
which created light, and the ingredients to make our sun.
Then we made eight planets, including one just like ours .
.
in the perfect place to support life.
Except that's not all.
Can you imagine the Earth without stars in the sky? Miserable.
We need more than that one star, we need a whole galaxy of them.
Still, that's easy.
Build one star, you've built them all.
We've made over 300 billion stars and put them all together into a galaxy.
Just like the one we live in, the Milky Way.
And we've put our sun with its solar system right out here, in a sleepy backwater on the outer edge.
Astronomers have even given it a galactic address.
Seriously, anyone can reach us at the local fluff, inside the local bubble at the Gould Belt of the galaxy's Orion arm.
I don't know what number.
Anyway, it's a good job we are out in the galactic sticks because we wouldn't want to make the mistake of being too close to the centre of things.
Because that is where lurks a supermassive black hole.
Yep, they really do exist.
These are once-giant stars that have collapsed in on themselves, pulling in millions of other stars around them.
They sit at the centre of most galaxies, including our own Milky Way.
Their gravity is so strong that not even light can escape its violent pull.
I think it's best we stay well away from that.
Where we are is exactly where we want to be.
This galactic neighbourhood really works for us.
But if we're building a universe, we need more than one galaxy.
We need a whole ocean of them.
Some spiral, some spidery, some lens-shaped, but each of them beautiful and unique.
And scientists have calculated that, to fill our universe, we need more stars than grains of sand on all the beaches on Earth.
But all is not well in the universe we've built.
The galaxies are flying apart.
I'm missing something that holds them together.
What have we forgotten? Our universe is missing a vital ingredient.
It's something that produces a massive gravitational force.
Without it, the universe would disintegrate.
Below my feet, is a lab full of people, all trying to find the stuff that holds the universe together.
Which is why I'm heading 1.
3km underground.
Scientists have worked out that what glues the galaxies together is the most common stuff there is.
It makes up a staggering 85% of everything.
They named it "dark matter".
Problem is, it's totally invisible and undetectable.
But that may be about to change, thanks to scientists like Professor Rick Gaitskell.
No music? Well, they did actually put some in once upon a time.
And? Nobody could agree on what to play! OK.
We also had a light in here at one point, it was all mod cons.
Rick's built a dark matter detector that's so sensitive he's had to protect it under 1.
3km of rock.
Why have we stopped here? I think this is it.
These are scientists, not miners.
I have a desperate urge to sing SINGS: # Hi-ho, Hi-ho! # I'm not going to.
And they've spent $100 million to look for something you can't see, you can't touch .
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and we haven't even found.
And this is what they've spent their money on.
So, is that it? Yep, that's the dark matter detector.
Or rather, this is the water tank that surrounds our dark matter detector.
I'm not being funny but it's like being in my loft, except I bet there's no dead pigeons in there, it's a pretty specialised environment.
It's got to be very clean.
The water inside this tank is extremely pure and it isolates our detector from all the radioactivity in the rock, and even you.
And in terms of search instruments, this is one of the biggest in the world or the best or? This is the most sensitive dark matter detector in the world and we're running it right now.
It's on? It's on.
So, how does the detector work? Well, suspended inside it is a capsule of a special gas called xenon.
It's the same stuff that's in this novelty toy.
It's very nice, it's a pleasing distraction, but why are you holding that thing? We've filled this plasma ball with xenon and we're exciting it using electricity.
As you can see, light is being generated.
The dark matter detector works on exactly the same principle.
We filled it with xenon, and when a dark matter particle comes in, the particle directly excites the atoms, and the atoms emit light, which we then detect.
So that's the event you're waiting to observe.
It's not a giant one of these, but that's to illustrate the idea of seeing those interactions.
That's right, and the particle events we're looking for are extremely infrequent.
We're operating this detector for weeks, months, years, looking for very, very occasional dark matter particles to interact with the xenon and we'll see the light coming from it.
It sounds complicated and it is.
Rick's been searching for dark matter particles for 23 years.
But scientists know it must exist, because they can see the effects of its gravity holding galaxies together.
If they can detect it, they'll have solved one of the greatest mysteries in science.
Rick, would it ruin millions of pounds' worth of research and years, decades in fact, of your own work if I turn the lights on? Don't touch any one of those buttons! That's six months' delay.
I won't touch anything.
Hands in pockets.
The first live results have started streaming in.
So, any of these spikes, that spike, that could be it, one of greatest moments in science ever? That spike could be it, the event you're looking for? That's right.
So, if that one was it, proof of the existence of dark matter, and I'm here? Yep.
Will I get my name on it? Well I was here.
If that's it, I was here just then.
If it is that event, we'll name it after you.
Every day you enjoy your unusual commute a mile under the ground.
If that happens, if that's the day that those spikes occur, it's a big deal! It will be an amazing feeling.
I think you'll hear the celebration.
Um, even though we're a mile underground it will be quite a roar.
I'll hear the champagne corks open! But I haven't got time to hang around talking about champagne.
I need to head back to the tower to add some elusive dark matter to the cosmic mix right now.
And it's working.
The gravity of the dark matter is pulling our galaxies back together.
Disaster averted.
Scientists have crunched all the numbers relating to dark matter through a supercomputer and come up with a way of seeing it.
And for the first time, we can show you what that looks like.
Each of these points of light is a galaxy made up of billions of stars.
They are held together in a vast gravitational web, created by ribbons of dark matter.
Adding that missing matter to a map of the universe means we can actually see how we, here on our planet, really are connected to even the remotest star.
And it'sit's kind of beautiful.
This vast web of dark matter .
.
holds the entire universe together.
As you look up on a clear night at that band across the sky, you're looking into the heart of the Milky Way - a tiny part of the great web of galaxies.
We are connected to it all because we are made of the same stuff.
And if anything had been a bit different - the Earth a bit too small, the sun too bright, the other planets too big, or the solar system in the wrong place in our galaxy .
.
then we simply wouldn't be here.