0:00:02 > 0:00:03Planet Earth.
0:00:05 > 0:00:06Our home.
0:00:09 > 0:00:10It's unique.
0:00:13 > 0:00:14It has life.
0:00:17 > 0:00:21But what's amazing, is none of it would exist without the sun,
0:00:21 > 0:00:25the moon and the stars around us.
0:00:25 > 0:00:29We are connected to the universe in the most fundamental ways.
0:00:30 > 0:00:35To find out how, I'm going to have to build my own.
0:00:35 > 0:00:38I'm going to open up a cosmic tool-box and work it out.
0:00:40 > 0:00:43And I'm going to build my universe up here,
0:00:43 > 0:00:47at the top of this impossibly high tower.
0:00:49 > 0:00:53It gives us the perfect platform to make something really big.
0:00:55 > 0:00:58Up here, we can do in seconds
0:00:58 > 0:01:02what it takes nature millions or billions of years to do.
0:01:02 > 0:01:06And to build a universe, I'm going to need a lot of help.
0:01:06 > 0:01:10I'll be honest, I'm faintly nervous.
0:01:10 > 0:01:11Was that it?
0:01:11 > 0:01:13Wow! Beautiful!
0:01:13 > 0:01:15Ohh, this is really difficult!
0:01:16 > 0:01:19I told you, seventies' moves! There they are.
0:01:19 > 0:01:22Like any construction project, there will be mistakes...
0:01:26 > 0:01:30..but from those mistakes, we'll get real insights into what
0:01:30 > 0:01:35makes our universe exactly right for us to exist.
0:01:35 > 0:01:37As an engineering challenge,
0:01:37 > 0:01:40this is about as big as it gets.
0:02:00 > 0:02:04How many times have you marvelled at the stars?
0:02:06 > 0:02:12Depending upon your frame of mind, the stars might appear distant
0:02:12 > 0:02:18and magical, or cold and remote, but the fact is, we are all
0:02:18 > 0:02:23made of the same stuff. And if you were to change anything about them,
0:02:23 > 0:02:30or about us, that connection, that delicate balance, would be lost.
0:02:30 > 0:02:34And this isn't an idle fancy, a romantic notion,
0:02:34 > 0:02:37it's essential, elemental and real.
0:02:43 > 0:02:46Without that connection, we wouldn't be here.'
0:02:48 > 0:02:54And to understand how it works, we need to build a universe.
0:02:57 > 0:02:59It's not a small task...
0:03:03 > 0:03:05..because Earth is in a solar system...
0:03:11 > 0:03:14..which is in just one tiny part of a galaxy...
0:03:16 > 0:03:20..that has over 300 billion stars within it.
0:03:26 > 0:03:30And there are half a trillion galaxies in the universe.
0:03:37 > 0:03:42So the job isn't really done until we build it all,
0:03:42 > 0:03:44from suns to galaxies.
0:03:47 > 0:03:53I'm going to need to construct all of this up here,
0:03:53 > 0:03:56at the top of my tower,
0:03:56 > 0:03:58where there's loads of room.
0:03:58 > 0:04:03To do this, we need to go back to the very start of everything.
0:04:08 > 0:04:11We need to start from scratch.
0:04:15 > 0:04:17In the case of our universe,
0:04:17 > 0:04:21the start of everything was 13.8 billion years ago...
0:04:21 > 0:04:23about.
0:04:23 > 0:04:24I do like a challenge.
0:04:33 > 0:04:38Most scientists agree that before the universe, there was nothing,
0:04:38 > 0:04:39nada.
0:04:41 > 0:04:45But out of that nothing, was created something...
0:04:45 > 0:04:51everything. It all happened in an event called the big bang.
0:04:51 > 0:04:56Thing is, the big bang is actually a misleading name for it
0:04:56 > 0:04:58because it wasn't a bang at all.
0:05:01 > 0:05:03There is an analogy that scientists
0:05:03 > 0:05:05and boffins use to get their head round this event.
0:05:09 > 0:05:11There's no explosion. It wasn't a bang.
0:05:13 > 0:05:15It's more like a balloon.
0:05:23 > 0:05:27The big bang was a rapid expansion, just like inflating a balloon.
0:05:48 > 0:05:50Now, of course, the universe expanded
0:05:50 > 0:05:52a lot quicker than our balloon.
0:05:55 > 0:05:57Unimaginably so.
0:05:58 > 0:06:00In a billionth of a second,
0:06:00 > 0:06:01it was already the size of our solar system.
0:06:01 > 0:06:03But you take the point.
0:06:06 > 0:06:09It's like a big expanding bubble of space.
0:06:13 > 0:06:17But there's something even more bizarre about the big bang.
0:06:19 > 0:06:23That universal expansion had no single point of origin.
0:06:28 > 0:06:32It happened everywhere and all at the same time.
0:06:34 > 0:06:37So one balloon isn't enough to demonstrate it.
0:06:37 > 0:06:39I need countless balloons.
0:06:42 > 0:06:47What's more, the expansion of the big bang is still happening today...
0:06:50 > 0:06:52..which means that wherever I am,
0:06:52 > 0:06:56I'm at the very centre of an expanding universe.
0:07:02 > 0:07:07And wherever you are, you, too, are at the centre of the universe.
0:07:27 > 0:07:32So we've had our big bang, but there is a little problem.
0:07:32 > 0:07:33It's dark.
0:07:34 > 0:07:39There is no light after a big bang because there are no stars.
0:07:39 > 0:07:42So, where can I get a star from?
0:07:42 > 0:07:44Well, fortunately, it turns out they make them
0:07:44 > 0:07:46just off the M40 near Oxford.
0:07:48 > 0:07:52BUZZING AND BEEPING
0:07:55 > 0:07:58Inside this billion-pound
0:07:58 > 0:07:59chamber...
0:08:02 > 0:08:03..we're going to squeeze,
0:08:03 > 0:08:07using colossal magnets, the only thing that was around after
0:08:07 > 0:08:12the big bang - hydrogen gas - until it ignites.
0:08:12 > 0:08:14And that IS a star.
0:08:14 > 0:08:16BUZZING AND BEEPING
0:08:18 > 0:08:23Sounds simple? It isn't. Don't try this at home.
0:08:23 > 0:08:25It is a job for the professionals.
0:08:27 > 0:08:32The chamber will briefly use more power than a city like Birmingham.
0:08:41 > 0:08:46And the ignition countdown begins 100m away,
0:08:46 > 0:08:49in the relative safety of mission control.
0:08:49 > 0:08:53We're now approaching the T minus one minute mark. T minus one minute.
0:08:53 > 0:08:57I'm joining starmaker-in-chief, Professor Steve Cowley.
0:08:57 > 0:08:59Steve, hello. Hello.
0:08:59 > 0:09:01I haven't touched anything and I promise not to
0:09:01 > 0:09:04because you're effectively creating a star here.
0:09:04 > 0:09:05Yeah.
0:09:05 > 0:09:09This looks AMAZING! This looks like I'd want it to look.
0:09:09 > 0:09:11Is it running now?
0:09:11 > 0:09:14We're about to fire it up, and for a few seconds,
0:09:14 > 0:09:17we'll reach the temperature of round about 100 million degrees.
0:09:17 > 0:09:19100 million degrees!
0:09:19 > 0:09:21What if it goes wrong, Steve?
0:09:21 > 0:09:22I mean, it's kind of extreme, isn't it?
0:09:22 > 0:09:25If something goes wrong, and it does do,
0:09:25 > 0:09:27the physicist in charge, she's got a red button,
0:09:27 > 0:09:33basically, and she will press the red button and it will abort the shot.
0:09:33 > 0:09:35The amount of energy in there...
0:09:36 > 0:09:39This isn't that far from my house is where I'm going!
0:09:39 > 0:09:40I live 50 miles away.
0:09:40 > 0:09:42But it does have a wall that's 2m.
0:09:42 > 0:09:43ALARM CLANGS
0:09:43 > 0:09:45What's that?
0:09:45 > 0:09:47It's the panic button. You have to run now.
0:09:47 > 0:09:50I'm not going to bother running. Really, what would be the point?
0:09:50 > 0:09:55If something really did go wrong, you could cause a lot of damage. Right.
0:09:55 > 0:09:58And I'm being allowed to give the trigger command...
0:09:59 > 0:10:00..to turn it on.
0:10:02 > 0:10:05So, what I'm going to do now is
0:10:05 > 0:10:08trigger the creation of a star, briefly, on Earth.
0:10:08 > 0:10:09Um... CLEARS THROAT
0:10:09 > 0:10:11Er, trigger, please.
0:10:11 > 0:10:12Can you accelerate, please?
0:10:12 > 0:10:14OK. Thank you.
0:10:15 > 0:10:20INTERMITTENT BUZZING
0:10:22 > 0:10:23WHOOSHING
0:10:23 > 0:10:26COMPUTERISED VOICE: 'Start.'
0:10:26 > 0:10:30It's starting up now. Right. Electrical current going through it.
0:10:33 > 0:10:35I'll be honest, I'm faintly nervous.
0:10:35 > 0:10:37How many times a day do you do this?
0:10:37 > 0:10:42'..Eight, seven, six, five, four,
0:10:42 > 0:10:46'three, two, one, zero.'
0:10:47 > 0:10:49There it is. Right.
0:10:52 > 0:10:54Look at the instability, it's shaking.
0:10:54 > 0:10:56This is mind-blowing.
0:10:57 > 0:11:00Inside the chamber is hydrogen.
0:11:00 > 0:11:03It was pretty much the only thing that existed in the darkness
0:11:03 > 0:11:05after the big bang.
0:11:07 > 0:11:10This machine heats and squeezes the hydrogen
0:11:10 > 0:11:16with such force that it ignites, creating a star and light.
0:11:16 > 0:11:21So, what's happening in that chamber right now,
0:11:21 > 0:11:25there, that is...that is a star on Earth.
0:11:27 > 0:11:30What's remarkable is the process of making a star
0:11:30 > 0:11:36doesn't just create light. It also makes brand-new ingredients,
0:11:36 > 0:11:40and this is going to help me build our universe.
0:11:40 > 0:11:44There's little white specks, which is exactly what stars are doing.
0:11:44 > 0:11:47It's turning hydrogen into helium.
0:11:48 > 0:11:51They start with hydrogen and they make helium
0:11:51 > 0:11:53and then they get helium and they make carbon,
0:11:53 > 0:11:55then they make oxygen. All the things you're made of,
0:11:55 > 0:11:58they are made bit by bit by bit in the centre of a star.
0:12:02 > 0:12:03Was that it? That's it.
0:12:03 > 0:12:07And was that the abort button there, you had all the... Whoa...
0:12:11 > 0:12:13Within a star, these different elements are made,
0:12:13 > 0:12:17but how do they then... They've got to get elsewhere.
0:12:17 > 0:12:19So, if it's a big enough star, it explodes -
0:12:19 > 0:12:22that's a supernova explosion - and it spews all that stuff,
0:12:22 > 0:12:24all those things you've made, all the carbon,
0:12:24 > 0:12:28all the iron, all the nickel, all the whatever, right, spews it out
0:12:28 > 0:12:32into the universe as dust, as particles,
0:12:32 > 0:12:33as this, that, and the other.
0:12:33 > 0:12:35These elements are created within it
0:12:35 > 0:12:37and then - boom! - all over the universe.
0:12:39 > 0:12:43Stars not only give us light,
0:12:43 > 0:12:46they are the element factories to build everything else.
0:12:49 > 0:12:52Back at my tower, I can now make light,
0:12:52 > 0:12:57and create all the stuff to build the rest of our universe.
0:12:58 > 0:13:01We just need a star to go supernova.
0:13:04 > 0:13:09A supernova is the biggest explosion there is, and for us
0:13:09 > 0:13:12it's an essential stage in our construction process
0:13:12 > 0:13:15because it takes all those elements created in big stars
0:13:15 > 0:13:17and scatters them everywhere.
0:13:18 > 0:13:20Just one note of caution though -
0:13:20 > 0:13:25when I say "big", I do mean "really, really big".
0:13:53 > 0:13:57And that supernova has now scattered all the ingredients
0:13:57 > 0:13:59we need to build everything.
0:14:01 > 0:14:05Floating around the tower, we've now got carbon,
0:14:05 > 0:14:07oxygen,
0:14:07 > 0:14:09iron...
0:14:13 > 0:14:16..and all the other elements we're going to need
0:14:16 > 0:14:18to make the planets,
0:14:18 > 0:14:20and even us.
0:14:27 > 0:14:30In that sense, everything
0:14:30 > 0:14:33really is stardust - you, me,
0:14:33 > 0:14:35everything you've ever seen
0:14:35 > 0:14:36or touched, or ever will.
0:14:36 > 0:14:40All of it created from the birth and death of a star.
0:14:40 > 0:14:41It's mind-blowing.
0:14:41 > 0:14:46And that cloud of gas and dust, called a nebula, also provides
0:14:46 > 0:14:48the ingredients for other stars.
0:14:51 > 0:14:54So we can now build our own star from it.
0:14:58 > 0:14:59We'll call it the sun.
0:15:07 > 0:15:10The real one took around 50 million years to form.
0:15:14 > 0:15:17Here, we've done it in seconds.
0:15:19 > 0:15:22And orbiting it is the dust and gas we'll need
0:15:22 > 0:15:25to make all the planets in our solar system.
0:15:35 > 0:15:38The first planet to start forming is Jupiter.
0:15:40 > 0:15:43But something's not going to plan.
0:15:43 > 0:15:46The young planet is starting to hoover up
0:15:46 > 0:15:49way too much of the gas and rock.
0:15:52 > 0:15:53And this process
0:15:53 > 0:15:55is slowing it down...
0:15:57 > 0:16:02..causing it to fall inwards, towards the sun.
0:16:02 > 0:16:04Which is a problem,
0:16:04 > 0:16:06because this is the very stuff
0:16:06 > 0:16:08that's going to build all the other planets.
0:16:08 > 0:16:12It's bad. What do we do to stop Jupiter gobbling up
0:16:12 > 0:16:14all our planetary building materials?
0:16:14 > 0:16:17Well, fortunately, I'm told there is a man who knows.
0:16:23 > 0:16:27This is Professor Alexei Filippenko.
0:16:31 > 0:16:35And THIS is a Fresnel lens.
0:16:36 > 0:16:40A simple enough device, but surprisingly powerful.
0:16:44 > 0:16:48Hi, Richard. So, how do we get rid of our rampaging Jupiter problem?
0:16:48 > 0:16:52Oh, well, look. Let me show you a demo that'll help illustrate it.
0:16:52 > 0:16:56Declan, why don't you tilt it there?
0:16:56 > 0:16:59It's on fire. Right away! It is on fire!
0:16:59 > 0:17:03But what's that got to do with Jupiter? It's a bit of wood?
0:17:03 > 0:17:06Yeah, well, what's happening is there's all these photons, all these
0:17:06 > 0:17:09little energetic particles of light coming from the sun and they're
0:17:09 > 0:17:13being focused here on this wood, heating it up, causing it to burn.
0:17:13 > 0:17:17In the case of the early solar system, the sun was much
0:17:17 > 0:17:20brighter than it is now and it acted for hundreds of thousands,
0:17:20 > 0:17:23or millions of years, so the photons were hitting
0:17:23 > 0:17:28the particles of dust and gas and heating them up, causing the
0:17:28 > 0:17:32atoms to actually evaporate away, to be blown out of the solar system.
0:17:32 > 0:17:35That meant that Jupiter was no longer
0:17:35 > 0:17:37slowing down and spiralling into the sun.
0:17:37 > 0:17:40Two things. One - there's a small fire over there.
0:17:40 > 0:17:42Yeah! Two -
0:17:42 > 0:17:45all the stuff in the way of Jupiter, slowing it up, wasn't wood.
0:17:45 > 0:17:48Yeah, I know, but look how powerful the sun is.
0:17:48 > 0:17:50Here's a rock. Why don't you put it right there.
0:17:50 > 0:17:52I don't want to get zapped by your machine.
0:17:52 > 0:17:54Declan won't zap you while you're putting it there.
0:17:54 > 0:17:57And we need to have some safety glasses on because
0:17:57 > 0:18:00it's going to get heated up so much from the trillions of photons
0:18:00 > 0:18:04hitting it that, er, it's actually going to snap, crackle and pop.
0:18:04 > 0:18:07Little pieces will come flying out. You've got more safety than me.
0:18:07 > 0:18:09Well, you know, my eyes are more important.
0:18:09 > 0:18:12I'm an astronomer, OK? OK. So let's put the rock in there...
0:18:12 > 0:18:13I can't argue with that, can I?
0:18:13 > 0:18:15I can't argue with that. I think you're OK.
0:18:17 > 0:18:18CRACKING AND POPPING
0:18:18 > 0:18:20Oh, hang on, that is the rock.
0:18:20 > 0:18:22Yeah, that's the rock flaking off...
0:18:22 > 0:18:25because of all the energetic photons hitting it.
0:18:25 > 0:18:30I am properly impressed with that. That is in seconds.
0:18:30 > 0:18:33It's heating up to 3,000 degrees Fahrenheit, OK?
0:18:33 > 0:18:36Now, over millions of years,
0:18:36 > 0:18:39the material is being blown out of the vicinity of Jupiter,
0:18:39 > 0:18:43so it's not growing any more and also it's not spiralling into the sun.
0:18:43 > 0:18:46So that saves us. Turn it off, Declan, I'm terrified.
0:18:46 > 0:18:50So this is another one of those events that had to happen
0:18:50 > 0:18:53at the right time, in the right place, and to the right extent.
0:18:53 > 0:18:55Too much of this for too long
0:18:55 > 0:18:57and there's nothing left to make your inner planets from.
0:18:57 > 0:18:59Yeah, that's exactly right.
0:19:03 > 0:19:05OK, a plan.
0:19:10 > 0:19:15I'm going to use light from the sun to clear a path for Jupiter...
0:19:17 > 0:19:20..to stop it slowing and spiralling inwards,
0:19:20 > 0:19:23gobbling all the building materials for our other planets.
0:19:25 > 0:19:28So, let's crank up the light from our sun...
0:19:31 > 0:19:33..and get those photons pumping.
0:19:48 > 0:19:51Jupiter's way is now clear.
0:19:53 > 0:19:57But luckily for us, the perfect amount of stuff
0:19:57 > 0:20:00is left behind to build the rest of our solar system.
0:20:02 > 0:20:04So we've got Jupiter.
0:20:08 > 0:20:10Now, how do we make our other planets?
0:20:12 > 0:20:15To find out what the planet formation was like in the early
0:20:15 > 0:20:18solar system, I need the help of the Texas Roller Derby.
0:20:18 > 0:20:20Excuse me. Sorry.
0:20:23 > 0:20:25Course I do.
0:20:25 > 0:20:28Sorry, ladies, excuse me. Can I join?
0:20:28 > 0:20:30Oh! Do I really need that? You need it to protect your head.
0:20:30 > 0:20:34Right. Well, I'll pop it on. Thank you.
0:20:34 > 0:20:38What's your skate name? Your name on the track, your alter ego?
0:20:40 > 0:20:42Hamster. Yeah, it's a long story.
0:20:42 > 0:20:44What about Slamster? Slamster!
0:20:44 > 0:20:47Oh! I'm loving that! WOMEN: Yeah, that's good.
0:20:47 > 0:20:50What sort of injuries can you acquire doing this?
0:20:50 > 0:20:52BOTH: Broken...everything!
0:20:52 > 0:20:56Broken ankles. Broken teeth. Hands, arms...
0:20:56 > 0:20:58I am really scared!
0:20:59 > 0:21:01You should be scared.
0:21:01 > 0:21:03Now, I know what you're thinking.
0:21:03 > 0:21:06Actually, I've no idea what you're thinking...
0:21:07 > 0:21:10..but bear with me. This is a genuine scientific demonstration
0:21:10 > 0:21:13of what happened in the early solar system.
0:21:14 > 0:21:17See you out there, girls. Oh, scared!
0:21:20 > 0:21:24I should say, I'm not what you'd call a regular skater.
0:21:34 > 0:21:39Imagine the sun in the centre of the track providing the gravity
0:21:39 > 0:21:43to pull around a whole host of rocks of different sizes.
0:21:43 > 0:21:46These wannabe planets are known as planetesimals.
0:21:51 > 0:21:57Some of these planetesimals were large, some very small,
0:21:57 > 0:21:59some moving in crazy orbits.
0:22:00 > 0:22:02U-u-ugh! Yee-ugh! Whoo-uh!
0:22:05 > 0:22:08All of them were affected by one another's gravity.
0:22:11 > 0:22:13So there were HUGE collisions.
0:22:16 > 0:22:20Potential planets were flung out of the solar system.
0:22:34 > 0:22:37And some wannabe planets were destroyed.
0:22:38 > 0:22:42Others had huge chunks ripped off them.
0:22:45 > 0:22:48What happened over just a few million years
0:22:48 > 0:22:50was a sort of planetary carnage.
0:22:55 > 0:22:59Oh! This is really difficult! Ha-ha-ha... Whoo-ooh!
0:23:09 > 0:23:13Eventually, some of the larger, more stable planets emerged
0:23:13 > 0:23:16and took the outside orbital lane.
0:23:16 > 0:23:20Whilst closer to the sun, smaller planets jostled for position.
0:23:24 > 0:23:27The remnants of this orbital tussle, the dead
0:23:27 > 0:23:32and never-to-be planets didn't just disappear, they still exist.
0:23:36 > 0:23:38A graveyard of broken worlds
0:23:38 > 0:23:42now orbits the sun as a ring of debris
0:23:42 > 0:23:44known as the asteroid belt.
0:23:48 > 0:23:53So here we are. Our solar system. There's Jupiter
0:23:53 > 0:23:55and, alongside it, the asteroid belt.
0:23:59 > 0:24:02And then the rest of the planets in our solar system.
0:24:04 > 0:24:07There's Mercury, nearest the sun.
0:24:08 > 0:24:11Its atmosphere has already been burnt away.
0:24:13 > 0:24:16Then Venus,
0:24:16 > 0:24:19a big bash early on has reversed its spin.
0:24:22 > 0:24:23And Mars,
0:24:23 > 0:24:26there's an enormous volcano here...
0:24:27 > 0:24:32..Olympus Mons, three times higher than Everest.
0:24:37 > 0:24:41Then Jupiter, bigger than all the planets put together.
0:24:45 > 0:24:48Saturn with its amazing rings.
0:24:49 > 0:24:52So light, it could float on water.
0:24:55 > 0:25:01Further out, Uranus, where summers last 21 Earth years, as do winters!
0:25:03 > 0:25:06And finally, Neptune.
0:25:07 > 0:25:12Freezing cold with hurricane winds of 1,000 kilometres an hour.
0:25:17 > 0:25:21Of course, there is one planet missing - ours.
0:25:21 > 0:25:25And exactly where it goes is critical
0:25:25 > 0:25:29because we need it to support one very fragile thing - life.
0:25:33 > 0:25:37Earth is unique amongst the planets in our solar system.
0:25:38 > 0:25:40It teems with life.
0:25:42 > 0:25:46Life which comes in countless different forms.
0:25:52 > 0:25:55So what is it that makes Earth so special?
0:25:58 > 0:26:03What do we need for life to exist when we're building a solar system?
0:26:18 > 0:26:22To find out, these scientists are attempting to reach
0:26:22 > 0:26:27one of the most inhospitable and extreme places on Earth.
0:26:28 > 0:26:29Sandro...
0:26:29 > 0:26:32SHE SPEAKS ITALIAN
0:26:32 > 0:26:33How far is it to the lake?
0:26:35 > 0:26:38SHE CONTINUES IN ITALIAN
0:26:38 > 0:26:43Where they're heading is so toxic, it is like an alien planet.
0:26:46 > 0:26:50If they can find life down there, it will help us understand
0:26:50 > 0:26:55the most basic requirements for life in our solar system.
0:26:55 > 0:26:57OK, I'll follow you.
0:26:57 > 0:26:59Be careful.
0:27:00 > 0:27:04To get there, they must risk a perilous 3km descent
0:27:04 > 0:27:07into eastern Italy's Frasassi cave system.
0:27:26 > 0:27:32Caves like these contain some of the last unexplored frontiers on Earth.
0:27:34 > 0:27:36Here I come.
0:27:38 > 0:27:40The expedition is led by
0:27:40 > 0:27:43astrobiologist Professor Jenn Macalady.
0:27:44 > 0:27:46Stay left, it's really tight.
0:27:47 > 0:27:51If you go to the right you are going to get stuck for sure.
0:27:51 > 0:27:53I'm not far behind.
0:27:53 > 0:27:55Use your feet.
0:27:55 > 0:27:58Yes, I am, it's er...
0:27:58 > 0:27:59tight.
0:27:59 > 0:28:00Breathe out.
0:28:02 > 0:28:03Yeah, that's it.
0:28:08 > 0:28:09You got it? Yep.
0:28:09 > 0:28:11You're through! Awesome.
0:28:11 > 0:28:14The things I do for science!
0:28:18 > 0:28:22After six hours, they're approaching the final descent.
0:28:25 > 0:28:29At the bottom, Jenn's hoping to shed light on the minimal
0:28:29 > 0:28:31conditions required for life.
0:28:32 > 0:28:34Aldo, coming down. OK!
0:28:42 > 0:28:45This is the Crystal Lake.
0:28:45 > 0:28:47Wow, it's beautiful.
0:28:50 > 0:28:51OK, I'm going down.
0:28:51 > 0:28:55Deep below its surface is home to what Jenn is looking for.
0:28:58 > 0:29:00It's a long way down, folks.
0:29:04 > 0:29:06Down here, all the normal things
0:29:06 > 0:29:09you need to support life have disappeared.
0:29:10 > 0:29:13Shall I come all the way down?
0:29:13 > 0:29:14There is no light.
0:29:16 > 0:29:19No animals or plants to feed off.
0:29:19 > 0:29:22And where they're going, there's no oxygen.
0:29:24 > 0:29:25We made it.
0:29:30 > 0:29:33The water is even poisonous
0:29:33 > 0:29:36but Jenn is hoping to find life there.
0:29:40 > 0:29:44The hunt will involve one of the most dangerous dives on the planet.
0:29:45 > 0:29:51Preparing to make the 80-foot plunge is ex-Navy diver Alejandro Crocetti.
0:29:52 > 0:29:53Perfecto.
0:29:55 > 0:29:57His dive time is strictly limited.
0:30:00 > 0:30:03Any kind of cave diving is very dangerous, because
0:30:03 > 0:30:06if there's a problem, you can't just pop up to the surface.
0:30:06 > 0:30:07You have a long way to go.
0:30:08 > 0:30:12But also, in this particular case, the water is actually toxic.
0:30:12 > 0:30:16So the chemicals that are dissolved in the water come through the skin,
0:30:16 > 0:30:20so that if you stay in that water for a while, then you become sick.
0:30:23 > 0:30:24You start to have symptoms
0:30:24 > 0:30:27that prevent you from making good decisions.
0:30:29 > 0:30:32Very quickly the passages become tighter and tighter.
0:30:32 > 0:30:35There is no room to manoeuvre.
0:30:35 > 0:30:40As soon as you move, you suspend all the sediment that's on the bottom
0:30:40 > 0:30:42and the visibility goes to zero very quickly.
0:30:44 > 0:30:47Fish would die instantly here.
0:30:49 > 0:30:53Very quickly the water will become sulphidic, more cloudy,
0:30:53 > 0:30:55more difficult to navigate through.
0:30:56 > 0:30:58We're not meant to be there really.
0:30:58 > 0:31:01It's a place where we can stay only for a few moments.
0:31:15 > 0:31:19Finally, they find what they've been looking for.
0:31:25 > 0:31:29These weird alien fingers are alive.
0:31:33 > 0:31:35They are bacteria,
0:31:35 > 0:31:39living on nothing more than rock dissolved in toxic water.
0:31:50 > 0:31:54Wow!
0:31:55 > 0:31:58Look at that, this is beautiful.
0:31:59 > 0:32:00Were there a lot like this?
0:32:00 > 0:32:04Multi. Multi? Si.
0:32:04 > 0:32:07Amazing sample, bravo. Grazie.
0:32:17 > 0:32:20This is life that we don't really understand yet.
0:32:20 > 0:32:25It's from water that's toxic, it's hostile, there's no oxygen.
0:32:25 > 0:32:28Where we've lost all the light, almost nothing to live on.
0:32:28 > 0:32:31All that's left really is water and rocks,
0:32:31 > 0:32:38and yet there's this beautiful form just full of interesting, weird,
0:32:38 > 0:32:42strange life, and it's extraordinary, because it represents
0:32:42 > 0:32:48something new that will help us explore for life on other planets.
0:32:51 > 0:32:55One of the things that we can learn from a sample like this is that
0:32:55 > 0:33:00wherever we have rocks and water, then somehow
0:33:00 > 0:33:04the water is going to allow life to thrive
0:33:04 > 0:33:06because it allows things to mix.
0:33:06 > 0:33:09It allows the rock to interact with life.
0:33:10 > 0:33:15So water is really, as we understand life, the most essential ingredient.
0:33:23 > 0:33:27Life as we know it can't exist without water
0:33:27 > 0:33:30but it must be liquid.
0:33:30 > 0:33:33Water, of course, comes in several different states.
0:33:38 > 0:33:42And where it is in our solar system is key.
0:33:43 > 0:33:47Too close to our sun, and water boils away.
0:33:50 > 0:33:54Too far away, like in the rings of Saturn...
0:33:55 > 0:33:58..and water freezes as hard as iron.
0:34:08 > 0:34:11Where we place our planet, then, is critical
0:34:11 > 0:34:13if we want to have liquid water.
0:34:13 > 0:34:18But how much leeway do we have? What about here near Mars,
0:34:18 > 0:34:21about 142 million miles from the sun?
0:34:27 > 0:34:31Well, to find out if Mars is suitable for liquid water,
0:34:31 > 0:34:34and for life, first you've got to get there.
0:34:39 > 0:34:40Mars.
0:34:45 > 0:34:49And NASA's rover, driving on the surface.
0:34:52 > 0:34:55Well, as close as you can get to its surface...
0:34:57 > 0:34:59..in Houston, Texas.
0:34:59 > 0:35:02Don't look at the bulldozer, that gives away that it's not Mars.
0:35:02 > 0:35:04Just so you know, that's not there!
0:35:04 > 0:35:06Or those cars. It spoils the effect!
0:35:08 > 0:35:12And my guide is NASA astronaut, Mike Gernhardt.
0:35:12 > 0:35:15Would it look anything like this? Yeah.
0:35:19 > 0:35:24NASA wants to put humans on the Red Planet in the next 20 years.
0:35:25 > 0:35:28Their goal is to find life.
0:35:33 > 0:35:38Problem is, despite there being hundreds of old river beds on Mars,
0:35:38 > 0:35:42all images show that the liquid water has vanished from the surface.
0:35:48 > 0:35:49So, what's happened to it?
0:35:52 > 0:35:57NASA is developing the kit to take us to the Red Planet to find out.
0:35:59 > 0:36:01This is Building Nine.
0:36:03 > 0:36:05A place I dreamt of as a kid...
0:36:06 > 0:36:08..and as an adult.
0:36:11 > 0:36:13You do have the coolest garage in the world.
0:36:13 > 0:36:17Yep, we got some really cool stuff. This thing is called the Robonaut.
0:36:17 > 0:36:20This is actually on the International Space Station at this point.
0:36:20 > 0:36:22This is called the Space Exploration Vehicle.
0:36:22 > 0:36:25This would be going to an asteroid, or possibly
0:36:25 > 0:36:27a moon of Mars like Phobos.
0:36:27 > 0:36:31Then with the reaction-controlled jets, we can hop.
0:36:31 > 0:36:34And an astronaut is on the end of a robot arm and we can have
0:36:34 > 0:36:38that on Mars, or the moon, or whatever planets we end up going to.
0:36:38 > 0:36:43All of this really informs us how to support these deep space missions.
0:36:43 > 0:36:46It's... Talking to you is just like going through a movie plot,
0:36:46 > 0:36:48constantly, it's so...
0:36:48 > 0:36:52Right, that all makes perfect sense...if you're you.
0:36:52 > 0:36:55RECORDING: 'We're now approaching the T minus one minute mark.
0:36:55 > 0:36:57'T minus one minute. T minus one minute.'
0:36:57 > 0:37:02And this is how man might get to Mars - the Orion spaceship.
0:37:02 > 0:37:05Are we getting in? We're going to get in.
0:37:05 > 0:37:08Oh! I so want to get in. A born astronaut, me.
0:37:08 > 0:37:11Here I go! Right, climbing across.
0:37:11 > 0:37:14You could bang your head on many things in here.
0:37:14 > 0:37:15Ye-ow!
0:37:15 > 0:37:17Yeah. Oh, yeah.
0:37:18 > 0:37:22Ooh! Yeah, I am so in.
0:37:22 > 0:37:23All right, good job!
0:37:23 > 0:37:25'T minus 20 seconds and counting.'
0:37:25 > 0:37:28'Having been to space, Mike's going to take me
0:37:28 > 0:37:31'through what a Mars launch would be like.'
0:37:31 > 0:37:33So, you climb in here.
0:37:33 > 0:37:36'Ten, nine...' You're strapped in.
0:37:36 > 0:37:38'Ignition sequence has started.'
0:37:38 > 0:37:40Then there's check lists you go through.
0:37:40 > 0:37:41'Five, four...'
0:37:41 > 0:37:45The clock hits zero... '..two, one, zero...'
0:37:45 > 0:37:48..and, all of a sudden, you have this big thrust in your back.
0:37:52 > 0:37:54And you're going up into space.
0:37:55 > 0:37:57'And we have liftoff.'
0:38:00 > 0:38:04We're going to be going faster than we ever have before
0:38:04 > 0:38:08so it's going to be a, you know, a real sporty ride.
0:38:08 > 0:38:10Sporty, that's a good word. Vigorous.
0:38:11 > 0:38:13'Liftoff...'
0:38:13 > 0:38:17So, four of us in here? Yep.
0:38:17 > 0:38:18Mars. Mars.
0:38:18 > 0:38:21It's not a short trip, is it? It isn't.
0:38:21 > 0:38:24Generally think of it as a nine-month trip out.
0:38:24 > 0:38:26Nine months?!
0:38:26 > 0:38:27What if somebody snores? I snore.
0:38:27 > 0:38:30I have actually flown in space with a guy that snored
0:38:30 > 0:38:33so loud that it kept me awake for days actually.
0:38:33 > 0:38:35Were you not just tempted to, you know, let him out?
0:38:35 > 0:38:37Nah, you can't do that.
0:38:37 > 0:38:39'OK, Houston, go in 30 seconds.'
0:38:39 > 0:38:40INDISTINCT RESPONSE
0:38:40 > 0:38:42'Mark one bravo.'
0:38:44 > 0:38:48Having reached the Red Planet, we now need to get out
0:38:48 > 0:38:50and search for Mars's water.
0:38:52 > 0:38:54So, I'll need one of these.
0:38:55 > 0:38:59Can I just say, this is an amazing privilege to get to do this.
0:38:59 > 0:39:04This is the Z1, next gen prototype.
0:39:04 > 0:39:08Besides me, Bruce Willis is the only non-astronaut who's ever been
0:39:08 > 0:39:11cleared to wear a real spacesuit. Oh, yeah.
0:39:11 > 0:39:14It's kind of like putting on a big onesie.
0:39:14 > 0:39:15Do I look faintly ridiculous?
0:39:15 > 0:39:17Ha-ha, yes!
0:39:20 > 0:39:23Wow! That's a glove and a half.
0:39:23 > 0:39:24That is serious.
0:39:26 > 0:39:28The NASA team are now putting me
0:39:28 > 0:39:31through a full Mars atmosphere suit simulation.
0:39:31 > 0:39:34That's got to go all the way up until we get to four three,
0:39:34 > 0:39:37which is operating pressure. OK. Sound good? Yes. OK
0:39:44 > 0:39:47I'm waiting for a massive burst of claustrophobia.
0:39:48 > 0:39:53'The atmosphere on Mars is incredibly thin, just 1% of Earth's,
0:39:53 > 0:39:57'so we need to pump up the suit, like inflating a tyre,
0:39:57 > 0:39:58'to hold my body together.'
0:39:58 > 0:40:01Swallowing. You're looking worried. Doing OK? I'm fine!
0:40:01 > 0:40:05Great. You're starting to look more muscular now, you know.
0:40:05 > 0:40:07No, I actually am, I'm actually flexing. We're at three.
0:40:07 > 0:40:08Three PSI. Three PSI.
0:40:08 > 0:40:10Four, one.
0:40:10 > 0:40:13Four, one. Popping ears.
0:40:13 > 0:40:16We're at operating pressure. Operating pressure. Wow!
0:40:16 > 0:40:19So, the arms are a little bit long for you in the suit
0:40:19 > 0:40:22but that's as small as they go because you're at the small end...
0:40:22 > 0:40:25This is like every shopping trip I've ever been on!
0:40:25 > 0:40:27The legs are a bit long on the jeans, sir,
0:40:27 > 0:40:30but that's the shortest we have. All right!
0:40:30 > 0:40:31OK! Yeah, it's...
0:40:31 > 0:40:34Why did I know it wasn't going to fit?
0:40:34 > 0:40:37So the next thing, we're going to release you from the donning stand.
0:40:43 > 0:40:46I only have short legs, so the bigger steps thing...
0:40:50 > 0:40:51MUSIC: "Stayin' Alive" The Bee Gees
0:40:57 > 0:41:01It had to happen. I told you - seventies' moves, there they are.
0:41:01 > 0:41:02I am super impressed.
0:41:02 > 0:41:06My daughters will be just cringing, "Dad, don't dance!"
0:41:06 > 0:41:10I'm dancing, yeah. See, look, girls, there it is.
0:41:10 > 0:41:13Suddenly I feel like doing this a lot.
0:41:13 > 0:41:15Oh, yeah, moonwalk!
0:41:20 > 0:41:21Were I on Mars right now,
0:41:21 > 0:41:24the atmosphere on the other side of this suit would be very different.
0:41:24 > 0:41:28What's it like? Yeah, it's basically almost no atmosphere.
0:41:28 > 0:41:31As we stand here, we're at 14.7 pounds per square inch,
0:41:31 > 0:41:34on Mars the pressure is roughly ten torr,
0:41:34 > 0:41:36which is like one hundredth of this.
0:41:37 > 0:41:40What would happen to me if I didn't have this?
0:41:40 > 0:41:42You'd be dead pretty soon. You'd probably have
0:41:42 > 0:41:45a couple to three minutes, and then that would be it.
0:41:45 > 0:41:50Clearly that's bad. Well, thank heavens for this thing then.
0:41:50 > 0:41:53'Mars is relatively close to Earth,
0:41:53 > 0:41:56'yet we certainly couldn't live there.
0:41:56 > 0:41:59'So, for life, what's wrong with the Red Planet?'
0:41:59 > 0:42:06Well, Mike's going to show us, with just a glass of water and a pump.
0:42:10 > 0:42:13So that's a pump and you're just pumping the air out of here
0:42:13 > 0:42:16until, you're creating a vacuum in there. Exactly.
0:42:16 > 0:42:18It actually won't be a pure vacuum, it'll be the same
0:42:18 > 0:42:23pressure as we have on Mars, which is very low but not complete vacuum.
0:42:23 > 0:42:27So you're just taking the air out to lower the pressure. Exactly.
0:42:29 > 0:42:31There it goes. There it goes.
0:42:32 > 0:42:36So there's no extra heat in there, that isn't at 100 degrees C?
0:42:36 > 0:42:38In fact that could be at zero degrees C.
0:42:43 > 0:42:46This is why you should always be careful with your spacesuit on Mars.
0:42:46 > 0:42:47Exactly.
0:42:47 > 0:42:51You don't want that happening to your blood. It's bad news.
0:42:51 > 0:42:52And that's why, so far as you know,
0:42:52 > 0:42:55there isn't any liquid water on Mars? Right.
0:42:55 > 0:42:58The atmosphere is so thin that if there were any liquid water,
0:42:58 > 0:43:00it would just evaporate like that.
0:43:01 > 0:43:04So, suddenly, holding on to your atmosphere becomes
0:43:04 > 0:43:07critical to keep your water along with it, how do you do that?
0:43:07 > 0:43:11So you need the right combination of things and one of them
0:43:11 > 0:43:13is the planet size because that effects the gravity,
0:43:13 > 0:43:17and if you don't have enough gravity then the atmosphere that was there
0:43:17 > 0:43:19will eventually go away. And then, as the atmospheric
0:43:19 > 0:43:22pressure drops, then the liquid water goes away.
0:43:22 > 0:43:24So there's this optimal size planet
0:43:24 > 0:43:28and Earth just happens to be one of those, so you need all these
0:43:28 > 0:43:31things to line up just, you know, shoot through the holes
0:43:31 > 0:43:34of the Swiss cheese in order to get the right combination to have life.
0:43:34 > 0:43:37And no liquid water, no life?
0:43:37 > 0:43:39Yeah.
0:43:39 > 0:43:41Complicated things to build, planets that you can live on,
0:43:41 > 0:43:43as it turns out.
0:43:49 > 0:43:52So there are a couple of things to think about
0:43:52 > 0:43:54when positioning our planet.
0:43:56 > 0:44:01The best place to put our planet for us is exactly where we are,
0:44:01 > 0:44:0693 million miles away from the sun, third rock along,
0:44:06 > 0:44:08in the part of space that we've called the "habitable zone",
0:44:08 > 0:44:12where we get just enough of a slug of the sun's energy -
0:44:12 > 0:44:14not too much or too little.
0:44:17 > 0:44:21It's a zone where water doesn't instantly freeze...
0:44:22 > 0:44:25..but also doesn't boil away.
0:44:32 > 0:44:36Both Earth and Mars are in that zone.
0:44:41 > 0:44:44But even then, as we've discovered with Mars,
0:44:44 > 0:44:48a planet has to be big enough to hold on to its water
0:44:48 > 0:44:51with an atmosphere to stop it escaping into space.
0:44:51 > 0:44:55So our planet has to be not only in just the right place,
0:44:55 > 0:44:58it has to be just the right size to support life.
0:45:09 > 0:45:13Where we place our planet needs to be precisely right.
0:45:15 > 0:45:19It must go between Mars and Venus,
0:45:19 > 0:45:22bang in the middle of the habitable zone.
0:45:24 > 0:45:25So there we are.
0:45:25 > 0:45:28All our planets in place around what scientists call
0:45:28 > 0:45:32a middle-aged yellow dwarf - our sun.
0:45:32 > 0:45:35We've built our solar system! Wonderful.
0:45:43 > 0:45:46We started with a supernova...
0:45:53 > 0:45:58..which created light, and the ingredients to make our sun.
0:46:03 > 0:46:10Then we made eight planets, including one just like ours...
0:46:13 > 0:46:15..in the perfect place to support life.
0:46:21 > 0:46:24Except that's not all.
0:46:24 > 0:46:29Can you imagine the Earth without stars in the sky? Miserable.
0:46:29 > 0:46:33We need more than that one star, we need a whole galaxy of them.
0:46:33 > 0:46:36Still, that's easy. Build one star, you've built them all.
0:46:43 > 0:46:46We've made over 300 billion stars
0:46:46 > 0:46:49and put them all together into a galaxy.
0:46:51 > 0:46:54Just like the one we live in, the Milky Way.
0:46:56 > 0:47:01And we've put our sun with its solar system right out here,
0:47:01 > 0:47:04in a sleepy backwater on the outer edge.
0:47:07 > 0:47:11Astronomers have even given it a galactic address.
0:47:11 > 0:47:14Seriously, anyone can reach us at the local fluff,
0:47:14 > 0:47:18inside the local bubble at the Gould Belt of the galaxy's Orion arm.
0:47:18 > 0:47:20I don't know what number.
0:47:20 > 0:47:24Anyway, it's a good job we are out in the galactic sticks
0:47:24 > 0:47:27because we wouldn't want to make the mistake of being
0:47:27 > 0:47:28too close to the centre of things.
0:47:34 > 0:47:38Because that is where lurks a supermassive black hole.
0:47:38 > 0:47:41Yep, they really do exist.
0:47:41 > 0:47:45These are once-giant stars that have collapsed in on themselves,
0:47:45 > 0:47:49pulling in millions of other stars around them.
0:47:49 > 0:47:51They sit at the centre of most galaxies,
0:47:51 > 0:47:54including our own Milky Way.
0:47:54 > 0:47:56Their gravity is so strong
0:47:56 > 0:47:59that not even light can escape its violent pull.
0:48:03 > 0:48:07I think it's best we stay well away from that.
0:48:07 > 0:48:10Where we are is exactly where we want to be.
0:48:10 > 0:48:14This galactic neighbourhood really works for us.
0:48:17 > 0:48:20But if we're building a universe, we need more than one galaxy.
0:48:20 > 0:48:24We need a whole ocean of them.
0:48:24 > 0:48:27Some spiral, some spidery, some lens-shaped,
0:48:27 > 0:48:29but each of them beautiful and unique.
0:48:38 > 0:48:42And scientists have calculated that, to fill our universe,
0:48:42 > 0:48:47we need more stars than grains of sand on all the beaches on Earth.
0:48:53 > 0:48:57But all is not well in the universe we've built.
0:49:05 > 0:49:07The galaxies are flying apart.
0:49:10 > 0:49:13I'm missing something that holds them together.
0:49:16 > 0:49:18What have we forgotten?
0:49:24 > 0:49:28Our universe is missing a vital ingredient.
0:49:28 > 0:49:33It's something that produces a massive gravitational force.
0:49:33 > 0:49:37Without it, the universe would disintegrate.
0:49:40 > 0:49:44Below my feet, is a lab full of people, all trying to find
0:49:44 > 0:49:47the stuff that holds the universe together.
0:49:47 > 0:49:50Which is why I'm heading 1.3km underground.
0:49:57 > 0:50:01Scientists have worked out that what glues the galaxies together is
0:50:01 > 0:50:05the most common stuff there is.
0:50:11 > 0:50:15It makes up a staggering 85% of everything.
0:50:18 > 0:50:20They named it "dark matter".
0:50:20 > 0:50:25Problem is, it's totally invisible and undetectable.
0:50:27 > 0:50:29But that may be about to change,
0:50:29 > 0:50:32thanks to scientists like Professor Rick Gaitskell.
0:50:34 > 0:50:36No music?
0:50:36 > 0:50:39Well, they did actually put some in once upon a time. And?
0:50:39 > 0:50:42Nobody could agree on what to play!
0:50:42 > 0:50:43OK.
0:50:43 > 0:50:47We also had a light in here at one point, it was all mod cons.
0:50:48 > 0:50:50Rick's built a dark matter detector
0:50:50 > 0:50:57that's so sensitive he's had to protect it under 1.3km of rock.
0:50:58 > 0:51:01Why have we stopped here? I think this is it.
0:51:09 > 0:51:12These are scientists, not miners.
0:51:12 > 0:51:13I have a desperate urge to sing...
0:51:13 > 0:51:16SINGS: # Hi-ho, Hi-ho! # I'm not going to.
0:51:16 > 0:51:22And they've spent $100 million to look for something
0:51:22 > 0:51:25you can't see,
0:51:25 > 0:51:26you can't touch...
0:51:29 > 0:51:31..and we haven't even found.
0:51:39 > 0:51:42And this is what they've spent their money on.
0:51:42 > 0:51:44So, is that it?
0:51:44 > 0:51:47Yep, that's the dark matter detector. Or rather,
0:51:47 > 0:51:51this is the water tank that surrounds our dark matter detector.
0:51:51 > 0:51:54I'm not being funny but it's like being in my loft,
0:51:54 > 0:51:57except I bet there's no dead pigeons in there,
0:51:57 > 0:51:59it's a pretty specialised environment.
0:51:59 > 0:52:01It's got to be very clean.
0:52:01 > 0:52:05The water inside this tank is extremely pure and it isolates our
0:52:05 > 0:52:09detector from all the radioactivity in the rock, and even you.
0:52:09 > 0:52:11And in terms of search instruments, this is
0:52:11 > 0:52:14one of the biggest in the world or the best or...?
0:52:14 > 0:52:16This is the most sensitive dark matter detector in the world
0:52:16 > 0:52:19and we're running it right now. It's on? It's on.
0:52:27 > 0:52:30So, how does the detector work?
0:52:30 > 0:52:34Well, suspended inside it is a capsule of a special gas
0:52:34 > 0:52:36called xenon.
0:52:37 > 0:52:40It's the same stuff that's in this novelty toy.
0:52:45 > 0:52:47It's very nice, it's a pleasing distraction,
0:52:47 > 0:52:49but why are you holding that thing?
0:52:49 > 0:52:52We've filled this plasma ball with xenon
0:52:52 > 0:52:55and we're exciting it using electricity.
0:52:55 > 0:52:57As you can see, light is being generated.
0:52:57 > 0:53:00The dark matter detector works on exactly the same principle.
0:53:00 > 0:53:02We filled it with xenon,
0:53:02 > 0:53:06and when a dark matter particle comes in, the particle directly
0:53:06 > 0:53:10excites the atoms, and the atoms emit light, which we then detect.
0:53:11 > 0:53:14So that's the event you're waiting to observe. It's not a giant one of
0:53:14 > 0:53:18these, but that's to illustrate the idea of seeing those interactions.
0:53:18 > 0:53:21That's right, and the particle events we're looking for
0:53:21 > 0:53:22are extremely infrequent.
0:53:22 > 0:53:27We're operating this detector for weeks, months, years,
0:53:27 > 0:53:31looking for very, very occasional dark matter particles to
0:53:31 > 0:53:33interact with the xenon and we'll see the light coming from it.
0:53:45 > 0:53:48It sounds complicated and it is.
0:53:48 > 0:53:53Rick's been searching for dark matter particles for 23 years.
0:53:53 > 0:53:57But scientists know it must exist,
0:53:57 > 0:54:00because they can see the effects of its gravity
0:54:00 > 0:54:03holding galaxies together.
0:54:03 > 0:54:05If they can detect it,
0:54:05 > 0:54:08they'll have solved one of the greatest mysteries in science.
0:54:11 > 0:54:16Rick, would it ruin millions of pounds' worth of research
0:54:16 > 0:54:20and years, decades in fact, of your own work if I turn the lights on?
0:54:20 > 0:54:25Don't touch any one of those buttons! That's six months' delay.
0:54:25 > 0:54:27I won't touch anything. Hands in pockets.
0:54:29 > 0:54:32The first live results have started streaming in.
0:54:32 > 0:54:36So, any of these spikes, that spike, that could be it,
0:54:36 > 0:54:38one of greatest moments in science ever?
0:54:38 > 0:54:42That spike could be it, the event you're looking for?
0:54:42 > 0:54:45That's right. So, if that one was it,
0:54:45 > 0:54:48proof of the existence of dark matter, and I'm here? Yep.
0:54:48 > 0:54:49Will I get my name on it?
0:54:49 > 0:54:52Well I was here. If that's it, I was here just then.
0:54:52 > 0:54:54If it is that event, we'll name it after you.
0:54:54 > 0:54:59Every day you enjoy your unusual commute a mile under the ground.
0:55:00 > 0:55:05If that happens, if that's the day that those spikes occur,
0:55:05 > 0:55:07it's a big deal!
0:55:07 > 0:55:09It will be an amazing feeling.
0:55:09 > 0:55:11I think you'll hear the celebration.
0:55:11 > 0:55:15Um, even though we're a mile underground it will be quite a roar.
0:55:15 > 0:55:18I'll hear the champagne corks open!
0:55:21 > 0:55:24But I haven't got time to hang around talking about champagne.
0:55:24 > 0:55:26I need to head back to the tower
0:55:26 > 0:55:31to add some elusive dark matter to the cosmic mix right now.
0:55:43 > 0:55:44And it's working.
0:55:46 > 0:55:51The gravity of the dark matter is pulling our galaxies back together.
0:55:57 > 0:55:59Disaster averted.
0:56:00 > 0:56:04Scientists have crunched all the numbers relating to dark matter
0:56:04 > 0:56:08through a supercomputer and come up with a way of seeing it.
0:56:08 > 0:56:11And for the first time, we can show you what that looks like.
0:56:18 > 0:56:23Each of these points of light is a galaxy made up of billions of stars.
0:56:26 > 0:56:31They are held together in a vast gravitational web,
0:56:31 > 0:56:33created by ribbons of dark matter.
0:56:41 > 0:56:45Adding that missing matter to a map of the universe
0:56:45 > 0:56:48means we can actually see how we, here on our planet,
0:56:48 > 0:56:52really are connected to even the remotest star.
0:56:52 > 0:56:54And it's...it's kind of beautiful.
0:57:04 > 0:57:07This vast web of dark matter...
0:57:09 > 0:57:12..holds the entire universe together.
0:57:46 > 0:57:51As you look up on a clear night at that band across the sky,
0:57:51 > 0:57:55you're looking into the heart of the Milky Way -
0:57:55 > 0:57:59a tiny part of the great web of galaxies.
0:58:02 > 0:58:04We are connected to it all
0:58:04 > 0:58:07because we are made of the same stuff.
0:58:11 > 0:58:14And if anything had been a bit different -
0:58:14 > 0:58:16the Earth a bit too small,
0:58:16 > 0:58:19the sun too bright,
0:58:19 > 0:58:21the other planets too big,
0:58:21 > 0:58:26or the solar system in the wrong place in our galaxy...
0:58:29 > 0:58:32..then we simply wouldn't be here.
0:58:54 > 0:58:57Subtitles by Red Bee Media Ltd