0:00:07 > 0:00:12Astronomers have long tried to understand our place as tiny specs
0:00:12 > 0:00:14in the vastness of the universe.
0:00:15 > 0:00:20But there is another expanse of the universe to explore,
0:00:20 > 0:00:23a bizarre realm in which we are giants,
0:00:23 > 0:00:26the weird world of the very small.
0:00:29 > 0:00:32This is a journey into the heart of matter,
0:00:32 > 0:00:35a journey down the biggest rabbit hole in history...
0:00:35 > 0:00:40It's perfectly possible that in the high-energy end of our data,
0:00:40 > 0:00:44right now we are occasionally making miniature black holes.
0:00:44 > 0:00:48..a journey smaller than you can see, smaller than an atom,
0:00:48 > 0:00:50where nothing is what it seems...
0:00:50 > 0:00:53The more fundamental things are,
0:00:53 > 0:00:57the nicer it is to look inside them.
0:00:57 > 0:01:02..into a wonderland which seems far removed from reality...
0:01:02 > 0:01:06Gravity is leaking into the extra dimensions.
0:01:06 > 0:01:09..down to the very smallest structure of the universe.
0:01:13 > 0:01:18We should expect space time to be not smooth as we presently imagine,
0:01:18 > 0:01:22but more like the foam of a cappuccino.
0:01:22 > 0:01:25The journey to find the smallest thing
0:01:25 > 0:01:28may take us into another universe altogether.
0:01:29 > 0:01:33But then of course, when you're down to this scale,
0:01:33 > 0:01:35you may have the whole universe in your hand.
0:01:35 > 0:01:38And at the bottom of the rabbit hole,
0:01:38 > 0:01:42we may find that our universe is just one of many.
0:01:58 > 0:02:02On top of an extinct volcano in the Canary Islands
0:02:02 > 0:02:05a strange telescope called MAGIC stands guard.
0:02:11 > 0:02:13It's on a ten-second stand-by
0:02:13 > 0:02:17to respond to the most violent explosions in the cosmos.
0:02:22 > 0:02:27With its laser-aligned panels, it is detecting the fallout
0:02:27 > 0:02:31from cosmic rays that have travelled half way across the universe.
0:02:35 > 0:02:40And it's helping physicists answer an eternal question.
0:02:40 > 0:02:45Well, at the end of the day, the question comes up, why do we exist,
0:02:45 > 0:02:49and not only we as mankind, but why does this planet exist,
0:02:49 > 0:02:50the solar system, the universe?
0:02:52 > 0:02:57If you want to know why the universe exists, you need to look,
0:02:57 > 0:03:00not to the very big, but to the very small.
0:03:00 > 0:03:06And it turns out there need to be a very small number of parameters
0:03:06 > 0:03:10very finely adjusted for the universe to be as it is
0:03:10 > 0:03:13and for us to sit in this universe, to be able to observe it.
0:03:13 > 0:03:16So I think this tells why it's important to understand
0:03:16 > 0:03:18how the laws of nature work.
0:03:24 > 0:03:27And the strangest thing about MAGIC,
0:03:27 > 0:03:30is that it's not really a telescope at all.
0:03:31 > 0:03:34It's the eyepiece of the biggest microscope in the world.
0:03:37 > 0:03:41It's just one of the incredible tools scientists have developed
0:03:41 > 0:03:45in their ongoing search for the smallest thing in the universe.
0:03:57 > 0:03:59Look at that!
0:03:59 > 0:04:01The nucleus and the electrons going around the atom.
0:04:01 > 0:04:04The exploration of the most distant,
0:04:04 > 0:04:07unreachable territory in our universe is challenging
0:04:07 > 0:04:09the minds of our greatest scientists.
0:04:09 > 0:04:13- Very nice.- This is very complex, very complicated.
0:04:13 > 0:04:15Am I getting there? Aargh!
0:04:15 > 0:04:17As you look smaller and smaller,
0:04:17 > 0:04:20no-one knows if there will ever be an end.
0:04:21 > 0:04:26Well, with me you'll see the more determination to find the next layer.
0:04:26 > 0:04:28I'm going to need a bigger collider soon.
0:04:28 > 0:04:31So we split, even split the nucleus.
0:04:32 > 0:04:35The hunt for the smallest thing in the universe
0:04:35 > 0:04:39is challenging our understanding
0:04:39 > 0:04:42of the very nature of space and time.
0:04:44 > 0:04:49Yes. This is it. This is the smallest piece.
0:04:49 > 0:04:51That is the smallest thing, isn't it?
0:04:53 > 0:04:56Nice analogy!
0:05:00 > 0:05:04The search for the smallest building blocks of the universe
0:05:04 > 0:05:07is one of the oldest in science.
0:05:07 > 0:05:11For almost 1,000 years, this medieval cathedral has looked over
0:05:11 > 0:05:13the streets of Aachen in Germany,
0:05:13 > 0:05:17an enduring monument of stone and glass.
0:05:18 > 0:05:21But if you look really, really closely,
0:05:21 > 0:05:23all is not what it seems.
0:05:28 > 0:05:32Professor Joachim Mayer is a man with a unique view on the world.
0:05:34 > 0:05:36He sees the bizarre changes that come about
0:05:36 > 0:05:39when you view the world in terms
0:05:39 > 0:05:41of the building blocks of stuff -
0:05:41 > 0:05:43atoms.
0:05:45 > 0:05:50Where you or I might see red, he sees gold.
0:05:51 > 0:05:53There are always two parts of your brain.
0:05:53 > 0:05:55If you look, if you come in as a human being
0:05:55 > 0:05:57but as a scientist as well,
0:05:57 > 0:06:02you are stunned by what people have built in these medieval times.
0:06:02 > 0:06:05And then you ask yourself what kind of materials did they use?
0:06:05 > 0:06:11If you look for example at these glass windows, it's very well known
0:06:11 > 0:06:17that actually nanotechnology is used in some of the colours, for example
0:06:17 > 0:06:21gold nanoparticles actually, produce the most durable red colour
0:06:21 > 0:06:24which can be produced. And it's still a miracle to us
0:06:24 > 0:06:29how in these ancient times, you know, the people found out
0:06:29 > 0:06:32that this is the most efficient way to produce a red colour.
0:06:32 > 0:06:38The red is just an illusion caused by the massive difference in scale
0:06:38 > 0:06:42between the tiny clumps of gold atoms and us -
0:06:42 > 0:06:44the giants who see red.
0:06:46 > 0:06:47It's one of the reasons
0:06:47 > 0:06:51scientists are obsessed with reaching the smallest scales.
0:06:51 > 0:06:55Things don't just get smaller, they change.
0:06:55 > 0:06:59Scientists have thought for a long time
0:06:59 > 0:07:02what are the smallest building blocks of our matter,
0:07:02 > 0:07:06and you can see beautiful matter around us.
0:07:06 > 0:07:10But just how small are these building blocks?
0:07:11 > 0:07:14If we start on the familiar scale of a human
0:07:14 > 0:07:16and zoom in ten times closer,
0:07:16 > 0:07:20we get to the size of a face.
0:07:20 > 0:07:26Magnify by ten once more, and we are looking at the iris of an eye.
0:07:26 > 0:07:30100 times closer and we can see a human hair,
0:07:30 > 0:07:32magnified 10,000 times.
0:07:33 > 0:07:36Microscopes have unveiled a world
0:07:36 > 0:07:38smaller than the wavelength of light.
0:07:38 > 0:07:43But the ability to see individual atoms has, until recently,
0:07:43 > 0:07:45been a dream.
0:07:51 > 0:07:54As microscopes have got bigger and more powerful,
0:07:54 > 0:07:58they have allowed us to peer ever smaller.
0:08:02 > 0:08:07It was the ancient Greeks who first dreamed up the idea of atoms.
0:08:10 > 0:08:14100 years ago, scientists proved they exist.
0:08:14 > 0:08:17But it's only in the last ten years
0:08:17 > 0:08:20that we've actually been able to see them.
0:08:25 > 0:08:26And now, behind these doors,
0:08:26 > 0:08:30Joachim Mayer has a machine that gives us the best possible view.
0:08:30 > 0:08:38MUSIC: "Also Sprach Zarathustra" by Richard Strauss
0:09:04 > 0:09:06It looks like a giant coffee maker!
0:09:09 > 0:09:13So this is our new PICO instrument,
0:09:13 > 0:09:16which has been installed about a year ago.
0:09:16 > 0:09:20And with its special new corrector for the chromatic aberration,
0:09:20 > 0:09:26is really a very unique machine which really offers us new possibilities.
0:09:26 > 0:09:30I think with its new capabilities, we consider it
0:09:30 > 0:09:32as the best electron microscope in the world.
0:09:32 > 0:09:36Being the best electron microscope in the world,
0:09:36 > 0:09:40PICO is very sensitive to its surroundings.
0:09:40 > 0:09:42Even a person's body heat would disturb it,
0:09:42 > 0:09:47so PICO has to be operated remotely.
0:09:48 > 0:09:51And, safely isolated from humans,
0:09:51 > 0:09:55PICO is able to unveil the secret world of the very small.
0:09:57 > 0:10:02We start our investigations at a very small magnification,
0:10:02 > 0:10:05which is equivalent to the highest magnification, which you can actually reach
0:10:05 > 0:10:09with a light microscope. At this magnification,
0:10:09 > 0:10:12the diameter of a human hair would be about that size.
0:10:12 > 0:10:15And now we can in magnification
0:10:15 > 0:10:19go at least a factor of 1,000 higher.
0:10:22 > 0:10:26And now we start to see the structure,
0:10:26 > 0:10:30actually these black dots are individual gold nanoparticles.
0:10:32 > 0:10:36And now you can see the individual atoms
0:10:36 > 0:10:39as they appear in this individual nanoparticle.
0:10:41 > 0:10:45So we see individual atoms aligned in the structure.
0:10:52 > 0:10:58It's hard to imagine just how small these dots of matter really are.
0:10:59 > 0:11:02But consider that each of us contains
0:11:02 > 0:11:06about seven billion, billion, billion atoms.
0:11:07 > 0:11:12That's more than the number of stars in the entire universe.
0:11:19 > 0:11:24PICO is, quite simply, the most powerful microscope in the world.
0:11:26 > 0:11:31After magnifying things a billion times, we can actually see
0:11:31 > 0:11:35the individual atoms that make up everything in the universe.
0:11:36 > 0:11:39This is the smallest thing we can see.
0:11:39 > 0:11:43It may well be the smallest thing we'll ever be able to see.
0:11:44 > 0:11:48These atoms look reassuringly like what you'd expect -
0:11:48 > 0:11:51solid round balls of stuff.
0:11:51 > 0:11:55But this is merely an illusion.
0:12:05 > 0:12:08If you want to find out what an atom really looks like,
0:12:08 > 0:12:10you need a whole new way of looking.
0:12:12 > 0:12:15Professor Andy Parker is trying to find things
0:12:15 > 0:12:18smaller than anyone has ever found.
0:12:23 > 0:12:25Well, the way to look inside an atom
0:12:25 > 0:12:27is to fire something at it very fast,
0:12:27 > 0:12:31and if you hit it hard enough it you can break it into little bits.
0:12:31 > 0:12:34He's using the most expensive experiment
0:12:34 > 0:12:36in the history of physics,
0:12:36 > 0:12:39one he helped design.
0:12:39 > 0:12:43At 17 miles long, and buried 100 metres underground,
0:12:43 > 0:12:48it is the biggest, and most famous particle accelerator in the world -
0:12:48 > 0:12:50the Large Hadron Collider.
0:12:50 > 0:12:53The ring goes right over behind the apartment blocks there,
0:12:53 > 0:12:56and then it goes five miles in that direction,
0:12:56 > 0:12:58roughly to the horizon,
0:12:58 > 0:13:01it comes round under the base of the mountains to here,
0:13:01 > 0:13:04and it sweeps back round,
0:13:04 > 0:13:07past those buildings there and back to point one.
0:13:09 > 0:13:14But once you start looking inside an atom, nothing is what it seems.
0:13:16 > 0:13:18People always imagine atoms as billiard balls,
0:13:18 > 0:13:20they've seen pictures of atoms as billiard balls
0:13:20 > 0:13:23or with a little electron going round quite a big nucleus,
0:13:23 > 0:13:25and this is a completely false picture.
0:13:25 > 0:13:28If you blew up an atom to the size of the Large Hadron Collider,
0:13:28 > 0:13:30so it would be five miles in that direction...
0:13:32 > 0:13:35..all around there on that piece of landscape...
0:13:36 > 0:13:39..then the nucleus would be about ten centimetres across,
0:13:39 > 0:13:40about the size of this tennis ball.
0:13:40 > 0:13:42So all the mass, all the weight of the atom
0:13:42 > 0:13:46is condensed into this tiny little nucleus,
0:13:46 > 0:13:50and the whole space around it is empty, apart from these few electrons buzzing around.
0:13:58 > 0:13:59The illusion of solidity
0:13:59 > 0:14:03comes from the fuzzy cloud of charged electrons.
0:14:03 > 0:14:04But on their own,
0:14:04 > 0:14:08they weigh virtually nothing and occupy no space.
0:14:09 > 0:14:12You need to go a 100,000 times smaller
0:14:12 > 0:14:17to get to the nucleus - a fizzing ball of protons and neutrons.
0:14:20 > 0:14:22The challenge here at the LHC,
0:14:22 > 0:14:26is to look inside the protons by smashing them to pieces.
0:14:30 > 0:14:33It's brute force and ignorance really.
0:14:33 > 0:14:35You are taking two things, which are very, very small,
0:14:35 > 0:14:38you don't really know what's inside them to start with,
0:14:38 > 0:14:40and you hit them together as hard as you can
0:14:40 > 0:14:44and they smash into tiny fragments and since you really don't know
0:14:44 > 0:14:46what the elaborate structure is inside, it's kind of like
0:14:46 > 0:14:50colliding two clocks together and then sweeping up the mess
0:14:50 > 0:14:53that you get and trying to figure out how the clock works.
0:15:02 > 0:15:04And you can't do it in a subtle way.
0:15:04 > 0:15:06There's no screwdriver to take a proton to bits
0:15:06 > 0:15:08and there's no plan of what's inside
0:15:08 > 0:15:12so you have to hit them very hard, then the fragments come flying out
0:15:12 > 0:15:14and from that we can try and work out,
0:15:14 > 0:15:17how all the cogs and gearwheels fit back together to make a proton.
0:15:22 > 0:15:25The debris from the proton collisions
0:15:25 > 0:15:28is detected by a vast machine called ATLAS.
0:15:31 > 0:15:33Everything interesting happens at the centre,
0:15:33 > 0:15:35that's where the particles collide.
0:15:40 > 0:15:45This engineering mock-up shows just one section of the real machine.
0:15:45 > 0:15:50And the sensitive instrument at its very heart is the part made by Andy.
0:15:50 > 0:15:53So I'm in the middle of the mock-up of ATLAS,
0:15:53 > 0:15:55and this is where all the action happens.
0:15:55 > 0:15:58The beams would come in from both ends through the centre here.
0:15:58 > 0:16:01This would of course be filled with detectors, but the beam pipe
0:16:01 > 0:16:04would run right through the centre and the particles, which are
0:16:04 > 0:16:07travelling in vacuum at almost the speed of light, collide head on
0:16:07 > 0:16:12just here, and do their stuff and then all the debris comes flying out
0:16:12 > 0:16:15and it flies through the detector layers...
0:16:17 > 0:16:20..and that's the debris that we use to reconstruct the collision
0:16:20 > 0:16:22that happens right here in the middle.
0:16:24 > 0:16:28And what you find when you smash a proton to pieces,
0:16:28 > 0:16:31is that it too is largely empty space.
0:16:32 > 0:16:37It is made of three tiny fundamental particles called quarks.
0:16:38 > 0:16:42But to reach the size of a quark we have to zoom in
0:16:42 > 0:16:441,000 times smaller.
0:16:52 > 0:16:56Some of the earliest machines used to probe the atom
0:16:56 > 0:16:58were bubble chambers, that produced exquisite pictures
0:16:58 > 0:17:01of the heart of matter.
0:17:03 > 0:17:07What you see here is a sudden explosion of particles from nowhere
0:17:07 > 0:17:09in the liquid of the bubble chamber and that is because
0:17:09 > 0:17:13a neutrino has hit an atomic nucleus there and smashed it to pieces,
0:17:13 > 0:17:16and we see the particles flying off.
0:17:18 > 0:17:19And that's anti-matter.
0:17:19 > 0:17:23That's matter and anti-matter being created from pure energy.
0:17:23 > 0:17:25Very, very beautiful image.
0:17:25 > 0:17:31So this is the map or a part of the map, of what nature can do.
0:17:32 > 0:17:34So it's part of the map of the universe.
0:17:38 > 0:17:42But now, after 80 years of smashing, the map is complete.
0:17:44 > 0:17:47In the summer of 2012 scientists at the LHC,
0:17:47 > 0:17:51announced the discovery of the famous Higgs particle.
0:17:52 > 0:17:55It's the final piece of what's called the Standard Model -
0:17:55 > 0:17:58a set of 17 fundamental particles
0:17:58 > 0:18:01including quarks and electrons
0:18:01 > 0:18:03that make up everything we know.
0:18:12 > 0:18:14But for physicists like Andy
0:18:14 > 0:18:17it's not the end of the story.
0:18:17 > 0:18:19Everyone's heard about the Higgs
0:18:19 > 0:18:23but the story goes much beyond that.
0:18:23 > 0:18:26In fact my main interest is beyond the Higgs.
0:18:29 > 0:18:33Like any great explorer, Andy is not satisfied
0:18:33 > 0:18:35that this is the end of the journey.
0:18:36 > 0:18:39There may be plenty more to discover.
0:18:39 > 0:18:42OK so we're in the ATLAS main control room,
0:18:42 > 0:18:46where the experiment crew, shift crew here are sitting taking data today.
0:18:46 > 0:18:48This is live data coming from the detector -
0:18:48 > 0:18:50collisions that are happening now.
0:18:50 > 0:18:53Collisions are happening 40 million times every second.
0:18:55 > 0:18:58And as the energy of the collisions increases,
0:18:58 > 0:19:02Andy will be able to look on smaller and smaller scales,
0:19:02 > 0:19:07even delving inside the so-called fundamental particles.
0:19:09 > 0:19:12Fundamental particles is a myth, I think.
0:19:12 > 0:19:13It looks at the moment
0:19:13 > 0:19:16as if quarks and electrons are point-like particles.
0:19:16 > 0:19:19We can't see any size to them but that is just because
0:19:19 > 0:19:22we haven't been able to measure very short distances around them.
0:19:22 > 0:19:25What I'd like to see is what's going on inside them.
0:19:25 > 0:19:27So we're looking for the innards of the quarks
0:19:27 > 0:19:29by smashing them together as hard as we can.
0:19:37 > 0:19:40In the search for the smallest piece of the universe,
0:19:40 > 0:19:43part of the problem may be knowing when to stop.
0:19:44 > 0:19:48Each new layer reveals great secrets.
0:19:48 > 0:19:50But does this search have an end?
0:19:52 > 0:19:55Or within every small thing,
0:19:55 > 0:19:57is there another...
0:19:58 > 0:20:00..and another?
0:20:18 > 0:20:21Perhaps the best known of all the fundamental particles
0:20:21 > 0:20:23is the electron.
0:20:24 > 0:20:27It underpins much of our modern lives,
0:20:27 > 0:20:31from computers to street lights to televisions.
0:20:31 > 0:20:35But for theoretical physicist professor Jeroen van den Brink,
0:20:35 > 0:20:39the electron might not be as fundamental as we think.
0:20:39 > 0:20:42The more fundamental things are,
0:20:42 > 0:20:45the nicer it is to look inside them.
0:20:46 > 0:20:51Physics it's always that something appears to be fundamental,
0:20:51 > 0:20:54and just because we believe it's fundamental we take the next step
0:20:54 > 0:20:57and try to look what's inside it.
0:21:10 > 0:21:15Jeroen's idea was that, rather than smashing electrons into pieces,
0:21:15 > 0:21:20he could find a different way to split its properties...
0:21:21 > 0:21:26the very properties that make it so useful.
0:21:26 > 0:21:30So the electron has three fundamental properties,
0:21:30 > 0:21:36charge, spin and orbital and theoretically
0:21:36 > 0:21:42it's definitely possible to split those three parts of the electron.
0:21:42 > 0:21:45If you do the mathematics
0:21:45 > 0:21:47there is no problem in doing that.
0:21:47 > 0:21:50If you do the quantum mechanics, it's completely allowed.
0:21:50 > 0:21:54So in principle you can split the electron,
0:21:54 > 0:21:55at least you can do it on paper.
0:21:55 > 0:22:01If you want to want to do it in practice, you need this...
0:22:01 > 0:22:03Watch your head here.
0:22:03 > 0:22:05..the Swiss Light Source,
0:22:05 > 0:22:08a million watt light bulb.
0:22:08 > 0:22:12This is an in vacuum undulator.
0:22:12 > 0:22:17The Swiss Light Source is in fact the Swiss X-ray Source.
0:22:17 > 0:22:19We have digital BPM systems.
0:22:19 > 0:22:23Inside the ring, under the care of Dr Andreas Ludeke,
0:22:23 > 0:22:27a beam of electrons creates the ultimate X-ray laser.
0:22:27 > 0:22:30This is a superconducting cavity.
0:22:30 > 0:22:34It's one of the most powerful, highly focused, narrow X-ray beams
0:22:34 > 0:22:36in the world.
0:22:36 > 0:22:40We have a high intense magnetic field in the middle.
0:22:40 > 0:22:45The perfect tool for probing down to the size of an electron.
0:22:45 > 0:22:47Jeroen's partner in electron splitting,
0:22:47 > 0:22:50the man who devised and runs the experiment,
0:22:50 > 0:22:52is Dr Thorsten Schmitt.
0:22:54 > 0:22:56So here we are in the so-called optical hutch,
0:22:56 > 0:23:01where all the crucial optical elements -
0:23:01 > 0:23:07mirrors which are optimized for X-rays and which are used
0:23:07 > 0:23:10for shaping the beam quality are sitting.
0:23:10 > 0:23:12- I can see it here.- Yeah.
0:23:14 > 0:23:19So when I come here I go to the equipment, I look at it,
0:23:19 > 0:23:25I admire it and then I go back and sit behind a computer
0:23:25 > 0:23:30or take my pen and paper and start to do the mathematics.
0:23:30 > 0:23:34I do not really understand what the stuff out here is exactly doing
0:23:34 > 0:23:39and I believe, I'm sure Thorsten does and they do the experiments.
0:23:44 > 0:23:49We have X-rays, which are coming in and hit a sample,
0:23:49 > 0:23:52and we will then in the end analyse the X-rays, which are re-emitted
0:23:52 > 0:23:56or scattered off from the sample.
0:24:01 > 0:24:03When the X-ray beam strikes,
0:24:03 > 0:24:07the electrons split into new quasi-particles.
0:24:09 > 0:24:14These particles, called spinons, orbitons and holons,
0:24:14 > 0:24:16carry the properties of the electron,
0:24:16 > 0:24:20and can travel off in different directions.
0:24:23 > 0:24:26This is actually the picture that tells the whole story.
0:24:26 > 0:24:30The most important part is here, this red part,
0:24:30 > 0:24:34and what's important is that it's wavy.
0:24:34 > 0:24:37And this waviness tells us that what happened in this experiment
0:24:37 > 0:24:41is that the electron was split into spinons and orbitons.
0:24:41 > 0:24:43So this is the picture
0:24:43 > 0:24:47that is the experimental proof that the electron has been split.
0:24:52 > 0:24:53Are you proud of that picture?
0:24:53 > 0:24:56I'm very proud of the picture.
0:25:03 > 0:25:06So the electron can be split into these three different particles,
0:25:06 > 0:25:11but, really, what can you do with those particles when you have them?
0:25:11 > 0:25:13I don't have a good answer to that.
0:25:13 > 0:25:18It's just cool to make these, make this electron that is so
0:25:18 > 0:25:22fundamental, that's so part... That's the first fundamental particle
0:25:22 > 0:25:26that was discovered, to see it split into its three different parts.
0:25:31 > 0:25:33That's what I like about the experiment.
0:25:37 > 0:25:41The electron has, in one sense, been split in three.
0:25:42 > 0:25:45But it's a measure of just how weird things are down here
0:25:45 > 0:25:49that it's still considered to be fundamental.
0:25:49 > 0:25:51Down at this scale,
0:25:51 > 0:25:55we just have to accept that the rules become deeply strange.
0:25:56 > 0:25:58And if we reach down even further,
0:25:58 > 0:26:01we may have to throw out the rule book altogether.
0:26:12 > 0:26:16Back at the LHC, far beyond the Higgs,
0:26:16 > 0:26:20smaller than the innards of a quark, Andy Parker believes ATLAS
0:26:20 > 0:26:26could reveal something that, at this tiny scale, shouldn't really exist.
0:26:27 > 0:26:31So this great big building here is at the top of the ATLAS pit.
0:26:31 > 0:26:32100 metres straight down is the detector,
0:26:32 > 0:26:34which is operating at the moment,
0:26:34 > 0:26:37so we're not allowed in the building for safety reasons.
0:26:37 > 0:26:41He is hoping to make one of the most fearsome objects in the universe -
0:26:41 > 0:26:43a black hole...
0:26:43 > 0:26:47Si je produis des problemes pour Atlas, je suis "eeeek"!
0:26:47 > 0:26:51..a place where gravity is so vastly strong that nothing -
0:26:51 > 0:26:53not even light - can escape.
0:26:53 > 0:26:58Problem is, if they open it, that could set off the pit alarms.
0:27:02 > 0:27:05It takes the entire mass of an imploding star,
0:27:05 > 0:27:08condensed into the space of a small town,
0:27:08 > 0:27:12to create the extreme gravitational pull of a black hole.
0:27:14 > 0:27:18They are normally vast, and live at the centre of galaxies.
0:27:18 > 0:27:23And yet Andy Parker is trying conjure a micro black hole
0:27:23 > 0:27:28right here at CERN, using just a couple of protons.
0:27:28 > 0:27:31It's perfectly possible that in the high-energy end of our data
0:27:31 > 0:27:34right now we are occasionally making miniature black holes.
0:27:37 > 0:27:40The protons are colliding below us, they come together,
0:27:40 > 0:27:43they have a lot of energy in them. And gravity cares about energy.
0:27:43 > 0:27:45It's the same as mass as far as gravity is concerned.
0:27:45 > 0:27:47So if you put a lot of energy in a small space,
0:27:47 > 0:27:49as we're doing right now,
0:27:49 > 0:27:52then you could potentially form a quantum-sized black hole.
0:27:52 > 0:27:53A very, very tiny black hole.
0:27:53 > 0:27:56It wouldn't be stable, it wouldn't last a long time
0:27:56 > 0:27:59and eat the planet, it would disappear in a puff of radiation,
0:27:59 > 0:28:02and we would see that puff of radiation in our detector.
0:28:05 > 0:28:09The only way it would be possible to make these micro black holes,
0:28:09 > 0:28:13at least 20,000 times smaller than a proton,
0:28:13 > 0:28:18is if, on the level of the really, really small, we discover
0:28:18 > 0:28:23that gravity is vastly stronger than it seems in everyday life.
0:28:26 > 0:28:30And that would change our view of the familiar world,
0:28:30 > 0:28:33and challenge something we all take for granted -
0:28:33 > 0:28:36that we live in a world of three-dimensional space.
0:28:38 > 0:28:41So this seems to be a perfectly ordinary three-dimensional world.
0:28:41 > 0:28:42There are three ways I can go.
0:28:42 > 0:28:46I can go forwards and backwards, side to side, up and down.
0:28:46 > 0:28:48There can't be anything much more than that, can there?
0:28:48 > 0:28:51So if I want to go up the tower, for example, over there,
0:28:51 > 0:28:55I go sideways, I go forwards and I go up.
0:28:55 > 0:28:57Seems to be the only possibilities.
0:29:01 > 0:29:03But not necessarily.
0:29:04 > 0:29:07If we could conjure up an extra dimension,
0:29:07 > 0:29:12it could explain how you get super gravity at the tiny scale.
0:29:13 > 0:29:17Because, although gravity seems strong in our everyday lives,
0:29:17 > 0:29:19it's actually pretty feeble.
0:29:30 > 0:29:32Gravity is a puzzle.
0:29:32 > 0:29:34It's very, very much weaker than the other forces -
0:29:34 > 0:29:37actually a million, million, million times weaker than the other forces.
0:29:37 > 0:29:39It feels strong to us - right here,
0:29:39 > 0:29:43I'm feeling uncomfortable about gravity pulling me over the edge.
0:29:43 > 0:29:46But that's because there's a whole planet there pulling me downwards.
0:29:50 > 0:29:53The other forces that are hard at work holding the world together,
0:29:53 > 0:29:56including the electromagnetic force,
0:29:56 > 0:29:58are all vastly stronger than gravity.
0:30:01 > 0:30:03So here's a little magnet.
0:30:03 > 0:30:06And this key, being held down
0:30:06 > 0:30:11by all the atoms in the entire planet pulling towards the centre.
0:30:11 > 0:30:14And this feeble little magnet can overcome
0:30:14 > 0:30:17the gravity of the whole planet quite easily.
0:30:17 > 0:30:19Now, why is gravity so weak?
0:30:19 > 0:30:22Well, one possible explanation is that it's not actually weak.
0:30:22 > 0:30:24It's just as strong as the other forces,
0:30:24 > 0:30:26but we're missing part of it,
0:30:26 > 0:30:29and gravity is leaking into the extra dimensions,
0:30:29 > 0:30:31and so when we calculate the strength of gravity,
0:30:31 > 0:30:33we're only seeing the piece that's in 3D.
0:30:35 > 0:30:39Most of our gravity could be leaking off into the fourth dimension.
0:30:39 > 0:30:42All we get is the leftovers.
0:30:43 > 0:30:47This would account for the feebleness of gravity,
0:30:47 > 0:30:50but where could this fourth dimension be hiding?
0:30:50 > 0:30:53Well, if there is an extra dimension, it's everywhere.
0:30:53 > 0:30:55The question is, why can't we see it?
0:30:58 > 0:31:02All the others we can go off to infinity along these directions
0:31:02 > 0:31:05but maybe the reason we can't see the fourth dimension is that
0:31:05 > 0:31:07it's actually curled up.
0:31:07 > 0:31:09If you went into it, you'd go round in a little circle
0:31:09 > 0:31:12and come back on yourself, just like if you travelled on the surface
0:31:12 > 0:31:15of the Earth far enough, you'd come back to where you started.
0:31:15 > 0:31:18But this would be on a very, very small scale.
0:31:20 > 0:31:23Hiding an extra dimension may sound tricky,
0:31:23 > 0:31:26but it's all a matter of scale.
0:31:27 > 0:31:29It's a very strange concept,
0:31:29 > 0:31:31but you can see it for people who live in a flat world.
0:31:31 > 0:31:35If we look down on the people down below, then they're
0:31:35 > 0:31:38moving around on a surface, which is pretty much flat, and looked at
0:31:38 > 0:31:41from this large distance up, it just looks completely flat
0:31:41 > 0:31:45and they move about, they cannot go up and down because they can't fly.
0:31:55 > 0:32:01From a great height, the tiny people seem to live in two dimensions.
0:32:03 > 0:32:06But if we zoom into the same scale as the ant people,
0:32:06 > 0:32:10you realise they can actually move up and down as well.
0:32:13 > 0:32:16Similarly, if we could get down to a small enough scale,
0:32:16 > 0:32:20we might find there is a fourth dimension curled up.
0:32:21 > 0:32:24It may sound an outlandish theory,
0:32:24 > 0:32:29but if Andy spots his baby black holes, all this would be true.
0:32:30 > 0:32:33If we did see evidence of black holes at the LHC, that would be
0:32:33 > 0:32:36absolutely amazing because it tells us that everything we think
0:32:36 > 0:32:40we know about gravity, general relativity and so on, isn't right.
0:32:40 > 0:32:43Then you would have demonstrated that the world is not
0:32:43 > 0:32:46three-dimensional, but four-dimensional or more.
0:32:46 > 0:32:48And you would have made a black hole in the lab.
0:32:48 > 0:32:50So you get the Nobel Prize for making a black hole in the lab,
0:32:50 > 0:32:53you get the Nobel Prize for proving general relativity wrong,
0:32:53 > 0:32:54and you get the Nobel Prize
0:32:54 > 0:32:57for demonstrating that the universe is multi-dimensional.
0:32:57 > 0:32:59I mean, how cool is that?
0:33:01 > 0:33:04On our journey to find the smallest thing in the universe,
0:33:04 > 0:33:07things have indeed become deeply strange.
0:33:08 > 0:33:11We have dived down a rabbit hole into a bizarre wonderland
0:33:11 > 0:33:16where extra dimensions may lie curled and hidden from our view.
0:33:16 > 0:33:21But that's just the beginning of the weirdness.
0:33:21 > 0:33:24As we look even smaller, beyond even the reach
0:33:24 > 0:33:28of the Large Hadron Collider, we have to rely on theory alone.
0:33:48 > 0:33:52Professor Michael Green is a founding father
0:33:52 > 0:33:54of one of the strangest theories in physics.
0:33:58 > 0:34:03A theory that tells us that the universe is made of strings.
0:34:09 > 0:34:12String theory starts off simply enough,
0:34:12 > 0:34:15but it leads to some mind-boggling conclusions.
0:34:19 > 0:34:22The fundamental particles, instead of being point-like objects
0:34:22 > 0:34:25are now thought of as being string-like objects.
0:34:28 > 0:34:31Instead of the 17 particles in the standard model,
0:34:31 > 0:34:34everything is made from a single object -
0:34:34 > 0:34:37an incredibly tiny loop of string.
0:34:39 > 0:34:42The characteristic feature of a string, which makes it
0:34:42 > 0:34:45different from a point is that it can vibrate
0:34:45 > 0:34:49and the different modes of vibration, the different notes, if you like,
0:34:49 > 0:34:52are seen as different kinds of particles.
0:34:54 > 0:34:56So there's this very appealing,
0:34:56 > 0:35:00almost poetic way in which string theory describes all the particles
0:35:00 > 0:35:03in terms of different notes on a string.
0:35:03 > 0:35:05It's like the music of the spheres almost.
0:35:10 > 0:35:13It's a beautifully neat idea.
0:35:13 > 0:35:17Each note from the vibrating string produces a different particle.
0:35:20 > 0:35:23There are, however, one or two problems.
0:35:25 > 0:35:27These strings are so small
0:35:27 > 0:35:33that no-one has ever seen anything remotely stringy.
0:35:35 > 0:35:39Depending on one's viewpoint, the size of these strings
0:35:39 > 0:35:41can vary an awful lot,
0:35:41 > 0:35:44from scales, which are sort of
0:35:44 > 0:35:47a millionth of a millionth of the size of a nucleus,
0:35:47 > 0:35:50to scales, which are much, much smaller than that.
0:35:53 > 0:35:56If string theory turned out to be true,
0:35:56 > 0:35:59then a string would be the smallest thing in the universe.
0:35:59 > 0:36:03The trouble is, once we get this small, the whole notion of small
0:36:03 > 0:36:06and big may get turned completely upside down.
0:36:08 > 0:36:12Supposing these are quarks and electrons, photons, the particles
0:36:12 > 0:36:18that constitute the standard model. Now we've got a problem because
0:36:18 > 0:36:22if you believe that they're made of something smaller, that's fine.
0:36:22 > 0:36:25You'll find something smaller inside.
0:36:25 > 0:36:28But if you believe in a theory like string theory,
0:36:28 > 0:36:31then the notion of smallness no longer means the same.
0:36:31 > 0:36:35Ah, I haven't actually reached it. It's even smaller than that.
0:36:35 > 0:36:37And there's an even smaller one than that.
0:36:37 > 0:36:43I have a little speck here, so that must be the smallest thing.
0:36:43 > 0:36:46But then of course when you're down to this scale,
0:36:46 > 0:36:49you may have the whole universe in your hand,
0:36:49 > 0:36:51because the, the universe itself started
0:36:51 > 0:36:54from something this scale and expanded into everything we know.
0:36:57 > 0:37:00So this thing, which you think is the smallest constituent,
0:37:00 > 0:37:02may in fact be the thing that contains all of us.
0:37:02 > 0:37:05So the notion, the difference between...
0:37:05 > 0:37:06Oops, I hadn't even got there.
0:37:06 > 0:37:09I dropped it, I dropped the little universe.
0:37:09 > 0:37:14The notion that this is the smallest constituent is paradoxically
0:37:14 > 0:37:18not at odds with the statement that it may also be the whole universe.
0:37:25 > 0:37:30String theory is underpinned by some fiendishly complex maths.
0:37:30 > 0:37:31But to make it work out,
0:37:31 > 0:37:35the theory invokes not just one new dimension,
0:37:35 > 0:37:39but says that we live in 11 dimensional hyperspace.
0:37:42 > 0:37:44If you could describe exactly how these extra dimensions
0:37:44 > 0:37:49are curled up, you'd be able to describe the exact nature
0:37:49 > 0:37:51of everything in the universe.
0:37:57 > 0:38:02The trouble is, there's more than one way to curl them up.
0:38:08 > 0:38:09So the equations of string theory
0:38:09 > 0:38:13have very large numbers of solutions, a humungously large number,
0:38:13 > 0:38:16any one of which might describe a possible universe
0:38:16 > 0:38:18with its own laws of physics,
0:38:18 > 0:38:21its own kinds of particles and its own kinds of forces.
0:38:21 > 0:38:25This whole body of solutions of string theory has been called
0:38:25 > 0:38:27the landscape string theory.
0:38:32 > 0:38:36Each peak in the landscape represents a different solution -
0:38:36 > 0:38:37a different possible universe.
0:38:41 > 0:38:44With each one just as likely to exist as the next.
0:38:45 > 0:38:48Most of these solutions would describe universes
0:38:48 > 0:38:50which are completely absurd.
0:38:50 > 0:38:56The typical ones would be the ones, which came into being and either
0:38:56 > 0:39:01ceased to exist after a very, very short time or exploded in such a way
0:39:01 > 0:39:06that matter exploded apart and never formed galaxies in the first place.
0:39:06 > 0:39:10The fact that our universe has existed for long enough
0:39:10 > 0:39:16for galaxies to form and evolve and planets to form and for life to form
0:39:16 > 0:39:22and us to exist tells us that we are living in a very untypical universe.
0:39:26 > 0:39:30If they could find the right solution - the right one
0:39:30 > 0:39:33out of 1 followed by 500 zeros,
0:39:33 > 0:39:37we'd have a neat explanation for everything in our universe.
0:39:39 > 0:39:42So the fascinating thing is the multiverse idea
0:39:42 > 0:39:44has been around for some time in astrophysics,
0:39:44 > 0:39:47but they didn't have a theoretical way of understanding it.
0:39:47 > 0:39:51And then along came string theory and then the two got wedded.
0:39:58 > 0:40:02Whichever way you look - whether up to the largest scale
0:40:02 > 0:40:06or down to the very smallest, our universe may not be alone.
0:40:08 > 0:40:12But for now, string theory remains a theory,
0:40:12 > 0:40:14with no experimental evidence
0:40:14 > 0:40:17for any of its mind-boggling predictions.
0:40:19 > 0:40:23As we look down in scale, things get increasingly cloudy.
0:40:25 > 0:40:29To stand a chance of seeing strings, we'd need a particle accelerator
0:40:29 > 0:40:33a million, billion times bigger than the LHC.
0:40:35 > 0:40:38Is this, then, the end of the line for the explorers
0:40:38 > 0:40:41searching for the smallest thing in the universe?
0:40:49 > 0:40:55It turns out there could well be a bottom of the rabbit hole -
0:40:55 > 0:40:57an ultimate limit of how small we can go.
0:40:59 > 0:41:03And there may be a way to reach this ultimate destination -
0:41:03 > 0:41:06it's just a rather roundabout route to get there.
0:41:17 > 0:41:22Dr Giovanni Amelino-Camelia is a theoretical physicist,
0:41:22 > 0:41:26who 12 years ago came up with an idea that could lead us
0:41:26 > 0:41:30to the ultimate destination at the bottom of the rabbit hole.
0:41:34 > 0:41:38An idea that may lead us to question the very fabric of the universe -
0:41:38 > 0:41:42the three dimensions of space and one of time, known as space-time.
0:41:45 > 0:41:50Space time to an ordinary person is space time.
0:41:50 > 0:41:52What is space time? There is no answer.
0:41:52 > 0:41:59To us, space time is, er... Do you understand what I'm trying to say?
0:41:59 > 0:42:02The challenge is that I don't have anything to work with
0:42:02 > 0:42:06because the person who listen to me thinks know space time very well,
0:42:06 > 0:42:10but then if I asked what is space time, he would have no answer.
0:42:12 > 0:42:14Space time, they think they know very well what it is.
0:42:14 > 0:42:17"For God's sake, space time! You know!"
0:42:17 > 0:42:20But "you know" is all they can say.
0:42:20 > 0:42:23So your audience is the worst,
0:42:23 > 0:42:27because they think they know a lot about this subject.
0:42:27 > 0:42:30But then they know nothing, completely nothing.
0:42:32 > 0:42:36You see what I'm trying to say? It's very tricky.
0:42:37 > 0:42:42If we have any notion of space-time, it is that it is smooth.
0:42:43 > 0:42:46We can move smoothly from one cafe to another,
0:42:46 > 0:42:49can be reasonably sure how long a journey will take.
0:42:54 > 0:42:58But maybe not if you get small enough.
0:43:01 > 0:43:05The ultimate small destination is known as the Planck length.
0:43:07 > 0:43:11It is the theoretical limit of how small anything can possibly be.
0:43:11 > 0:43:15Some speculate that this could be the ultimate level.
0:43:15 > 0:43:20I mean, this could be where the laws of nature are fundamentally written.
0:43:25 > 0:43:30But to get to the Planck length, you have to look a hundred,
0:43:30 > 0:43:33million, billion times smaller than a quark.
0:43:38 > 0:43:39At this tiniest of scales,
0:43:39 > 0:43:44we may find answers not just about the smallest lump of stuff,
0:43:44 > 0:43:48but about the very nature of space
0:43:48 > 0:43:51and time in which all the stuff sits.
0:43:59 > 0:44:02What could be conceptually more fascinating than
0:44:02 > 0:44:04learning about the structure of space time?
0:44:06 > 0:44:10But our current theories with all their limitations suggest
0:44:10 > 0:44:13that at this Planck scale that we're talking about,
0:44:13 > 0:44:21we should expect space time to, to be not smooth as we imagine
0:44:21 > 0:44:26but more like, well, more like the foam of a cappuccino
0:44:26 > 0:44:33and actually perhaps in, in a violently dynamical way.
0:44:37 > 0:44:41The Planck length is where the rules of the large
0:44:41 > 0:44:44and the rules of the small collide in a heady brew
0:44:44 > 0:44:47called quantum gravity.
0:44:49 > 0:44:56It's a seething tempest of space and time known as space-time foam, where
0:44:56 > 0:45:02the very fabric of space and time twist and turn in every direction.
0:45:05 > 0:45:07It is where the two great pillars of modern physics,
0:45:07 > 0:45:11general relativity and quantum mechanics,
0:45:11 > 0:45:13may finally be reconciled.
0:45:15 > 0:45:18If we could understand what is happening down here,
0:45:18 > 0:45:21we could end up with a theory of everything.
0:45:24 > 0:45:28We are really far, far away from, from this realm,
0:45:28 > 0:45:35and yet some of the most conceptually striking questions
0:45:35 > 0:45:39about what, how is the universe made,
0:45:39 > 0:45:45what are its basic rules, appear to reside in this distant scale.
0:45:46 > 0:45:50So it's... At one side, we have this feeling of not having
0:45:50 > 0:45:56any access to it, and yet it appears to be the place where
0:45:56 > 0:46:01most of the answers we are seeking are somehow hidden.
0:46:06 > 0:46:09All roads in physics lead to the Planck length.
0:46:09 > 0:46:11But until recently,
0:46:11 > 0:46:16no-one had a clue how we would ever know anything about it.
0:46:16 > 0:46:20It was a problem Giovanni was determined to solve,
0:46:20 > 0:46:23seeking inspiration and reassurance in the cafes of Rome.
0:46:25 > 0:46:29I never understood what triggers an idea.
0:46:29 > 0:46:34And it's kind of reassuring to be reminded that all this is
0:46:34 > 0:46:36all about small - important, conceptually important,
0:46:36 > 0:46:39but small - I'm still here, the Coliseum is still there.
0:46:39 > 0:46:44When you're stuck chasing a certain answer,
0:46:44 > 0:46:49you often discover that all it took to find the answer
0:46:49 > 0:46:53was to look at the same problem from a different angle.
0:46:53 > 0:46:54MOBILE PHONE RINGS
0:46:54 > 0:46:56From the office.
0:46:57 > 0:46:59Pronto.
0:46:59 > 0:47:0312 years ago, Giovanni had a flash of inspiration
0:47:03 > 0:47:05that we could reach the unreachable.
0:47:08 > 0:47:12Over the last decade or so, what we started to figure out is
0:47:12 > 0:47:17that it is possible to get indirect information on the Planck scale.
0:47:18 > 0:47:22We cannot build a microscope that show us, shows us
0:47:22 > 0:47:26the structure of space time at the Planck scale,
0:47:26 > 0:47:30but we can get indirect evidence about the Planck scale
0:47:30 > 0:47:33structure of space time is made.
0:47:33 > 0:47:37Any explorer will tell you that if the way ahead is blocked,
0:47:37 > 0:47:40you have to set off in a new direction.
0:47:43 > 0:47:47Instead of trying to look directly down at the smallest scale,
0:47:47 > 0:47:53the idea is to look up at the very biggest scale possible -
0:47:53 > 0:47:56the entire universe.
0:48:07 > 0:48:10It's an idea that is now reality...
0:48:12 > 0:48:16..and a trick that is now being performed by the MAGIC telescope.
0:48:24 > 0:48:27The idea is to use the vastness of the universe
0:48:27 > 0:48:30as a giant magnifying glass.
0:48:44 > 0:48:48Dr Robert Wagner is using this unique instrument to peer
0:48:48 > 0:48:51at some of the most distant and cataclysmic events in the universe.
0:48:54 > 0:48:57Under good conditions, as we have them right now,
0:48:57 > 0:49:00we record 200 gamma ray or cosmic ray showers per second.
0:49:03 > 0:49:08The Earth is constantly being bombard by high-energy cosmic rays,
0:49:08 > 0:49:11gamma rays, the most energetic form of light.
0:49:14 > 0:49:17But Robert is looking for the most extreme of these -
0:49:17 > 0:49:21gamma ray bursts from colliding neutron stars or exploding
0:49:21 > 0:49:24black holes in distant galaxies.
0:49:26 > 0:49:30Gamma ray bursts are very violent events in the universe
0:49:30 > 0:49:35and one key characteristic of them is that we cannot predict them.
0:49:35 > 0:49:38So they can take place at any time at any place on the sky.
0:49:38 > 0:49:41We get the information from satellite experiments.
0:49:41 > 0:49:44This information is transmitted in an automatic way down here,
0:49:44 > 0:49:48it takes about ten seconds, and then the telescopes will fully
0:49:48 > 0:49:51automatically go to those gamma ray burst locations.
0:49:55 > 0:49:57With these light weight telescopes
0:49:57 > 0:50:02we're able to move to any point in the sky within only 20 seconds.
0:50:08 > 0:50:12Those bursts last anything between one and 1,000 seconds.
0:50:12 > 0:50:14Most of the bursts are really short lived.
0:50:14 > 0:50:19So it's of great essence to be there as fast as possible.
0:50:22 > 0:50:25Catching these violent but fleeting events
0:50:25 > 0:50:27takes many nights of patient observing.
0:50:34 > 0:50:38Well, this is a place I go right after the observations,
0:50:38 > 0:50:42and this of course gives a quite different feeling
0:50:42 > 0:50:44from looking at screens.
0:50:44 > 0:50:47You look at the real sky and actually the stuff
0:50:47 > 0:50:50we are observing and hoping to detect is somewhere up there.
0:50:54 > 0:50:59Those black holes and galaxies, they are so far very away,
0:50:59 > 0:51:03but at the same time, when you come here,
0:51:03 > 0:51:07you realise they are real because, you know, all the photons
0:51:07 > 0:51:10which hit my eye right now from those stars, they are real.
0:51:15 > 0:51:18Although Robert spends his nights looking out
0:51:18 > 0:51:23into the far reaches of the cosmos, he is actually trying to find out
0:51:23 > 0:51:27how the universe works on the very smallest scale.
0:51:30 > 0:51:33Things up there are so very, very far away.
0:51:34 > 0:51:38The farthest galaxy we are looking at is shining light at the time
0:51:38 > 0:51:41when the universe was just half its age,
0:51:41 > 0:51:44it takes the light 7 billion years to get to here.
0:51:44 > 0:51:47So that's a distance which, personally,
0:51:47 > 0:51:52I cannot imagine, myself, right? It's a very abstract number.
0:51:52 > 0:51:55At the same time, the scales we are looking at if we want to get to
0:51:55 > 0:52:01the shortest scales are as similar small as this distance is large.
0:52:01 > 0:52:05So it's really hard to imagine these things on scales,
0:52:05 > 0:52:07which we see here on Earth.
0:52:10 > 0:52:15But Robert's not really interested in the explosions themselves.
0:52:15 > 0:52:20They act as the biggest particle accelerator in the universe,
0:52:20 > 0:52:23way more powerful than anything we could ever achieve here on Earth.
0:52:26 > 0:52:29He is interested in what happens to the particles,
0:52:29 > 0:52:32in this case, photons, while they travel towards us
0:52:32 > 0:52:34on their 7-billion year journey
0:52:34 > 0:52:39through what seems like smooth, empty space.
0:52:41 > 0:52:45But any distortions in the structure of space-time at the Planck scale
0:52:45 > 0:52:50would affect photons of different energies in different ways.
0:53:02 > 0:53:06Essentially, it's quite comparable to cars driving on a road.
0:53:07 > 0:53:11A big car will not feel the fine structure of the road,
0:53:11 > 0:53:16it will just roll along and will be, you know, just as fast as normal.
0:53:16 > 0:53:18Whereas a small car, like a model car,
0:53:18 > 0:53:23will feel every tiny ripple in the structure of the street.
0:53:35 > 0:53:37The large car would be the low-energy photon,
0:53:37 > 0:53:40because there is nearly no interaction with the structure
0:53:40 > 0:53:42or the ripples in the road.
0:53:42 > 0:53:45Whereas the small car would be the high-energy photon,
0:53:45 > 0:53:49because it's smaller, there are more interactions with the road,
0:53:49 > 0:53:51and this makes the photon travel slower.
0:53:56 > 0:53:58The difference in speed is tiny.
0:53:58 > 0:54:02But the length of the journey, half way across the universe,
0:54:02 > 0:54:07could magnify the effect into something we might be able to see.
0:54:13 > 0:54:16We just let those photons travel along the universe,
0:54:16 > 0:54:19and of course they travel for billions of light years,
0:54:19 > 0:54:24and only that long travel time makes this tiny effect visible to us,
0:54:24 > 0:54:27which is to say, after such long travel,
0:54:27 > 0:54:31we expect a few seconds' delay of photons of different energies,
0:54:31 > 0:54:35and of course this is a delay which can easily be measured
0:54:35 > 0:54:36with the MAGIC telescopes.
0:54:44 > 0:54:49In 2005, just a few months after switching on the telescopes,
0:54:49 > 0:54:54a gamma ray outburst from an active galactic nucleus tickled
0:54:54 > 0:54:58the MAGIC mirrors, giving Robert his first tantalising glimpse
0:54:58 > 0:55:01down to the smallest place in the universe.
0:55:01 > 0:55:06It was the first time ever we observed such an effect,
0:55:06 > 0:55:09or, to put it in cautious words, the hint of such an effect.
0:55:09 > 0:55:11So clearly we were absolutely stunned.
0:55:16 > 0:55:20Soon, we realised there is something in this data, which is extraordinary.
0:55:23 > 0:55:25As soon as we dig deeper and deeper in the data,
0:55:25 > 0:55:31it became apparent that photons of different energies may have
0:55:31 > 0:55:33different arrival times at the instrument.
0:55:39 > 0:55:43Those photons had to travel billions of light years.
0:55:43 > 0:55:47The effect was on the order of seconds, maybe five seconds.
0:55:50 > 0:55:52The Planck length is so small
0:55:52 > 0:55:55that after a race of seven billion years,
0:55:55 > 0:56:00the photons finished with a gap of just five seconds.
0:56:00 > 0:56:03There are two possibilities here.
0:56:03 > 0:56:07The first is that the photons rather inexplicably set off
0:56:07 > 0:56:09five seconds apart.
0:56:09 > 0:56:13The other explanation is more revolutionary.
0:56:13 > 0:56:17This five-second delay could be our first glimpse of the smallest thing
0:56:17 > 0:56:23in the universe, the first evidence of a lumpiness in space-time.
0:56:24 > 0:56:29If true, it would shatter one of the most basic rules of physics.
0:56:31 > 0:56:35To put it in simple terms, the speed of light is not constant.
0:56:35 > 0:56:38It is dependent on the energy of the photon.
0:56:43 > 0:56:45And that's revolutionary
0:56:45 > 0:56:48because it's one of the fundamental laws of physics.
0:56:48 > 0:56:50Einstein predicted speed of light is a constant,
0:56:50 > 0:56:53no matter what you do, no matter where you are.
0:56:53 > 0:56:55Under no circumstances should there be
0:56:55 > 0:56:57a difference in the speed of light.
0:57:00 > 0:57:04The conclusion from our measurements that this is not the case
0:57:04 > 0:57:07would mean quite a revolution of physics.
0:57:16 > 0:57:19The MAGIC observations provide a tantalising glimpse
0:57:19 > 0:57:22of what awaits us at the smallest structures of space.
0:57:26 > 0:57:28But to get there,
0:57:28 > 0:57:32we've had to harness the entire expanse of the universe.
0:57:38 > 0:57:42The journey to the very small is one of the most epic in science.
0:57:44 > 0:57:47It takes us beyond the limits of what we can see...
0:57:50 > 0:57:52..inside fundamental particles,
0:57:52 > 0:57:55which may not be so fundamental after all...
0:57:56 > 0:58:01..through a wonderland of extra dimensions and multiple universes...
0:58:03 > 0:58:06..down to the smallest place in the universe,
0:58:06 > 0:58:09a place that could change the face of physics.
0:58:13 > 0:58:18And surely we expect a revolution in the laws of physics not
0:58:18 > 0:58:22smaller than the one that took us from Newton's laws
0:58:22 > 0:58:25to quantum mechanics a century ago.
0:58:42 > 0:58:46Subtitles by Red Bee Media Ltd