BBC_The Big Bang Machine
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00:0013.7 billion years after it all began, we're about to go back to the beginning of time.
00:24With the largest and most complex scientific experiment ever attempted, the Large Hadron
00:33Collider, or LHC, has just one simple but audacious aim, to recreate the conditions
00:41of the Big Bang, in an attempt to answer the most profound questions about our universe.
00:53The goal of particle physics is to understand the universe in which we live. We want to
01:00know why things are the way they are, how they work, what everything is. We want to
01:07understand.
01:11If you're going to go for the big questions, then you have to go for it. There's no point
01:17in sort of messing around. If you really want to understand how the universe ticks,
01:23the LHC is what you need.
01:27When the switch is thrown, this could be either the beginning of the end, when we find that
01:33our theories of what existed just after the Big Bang are right, or it could be the end
01:40of the beginning, where we discover that the universe is more mysterious and more beautiful
01:47than we could possibly have imagined.
02:10The Large Hadron Collider spans the French-Swiss border just outside Geneva. It's the largest
02:20particle accelerator ever constructed.
02:28I'm Brian Cox, and I've been helping build it along with thousands of other scientists
02:33at CERN, the European Organisation for Nuclear Research.
02:42This is the experiment, if you like, Q1, Q2, Q3.
02:48One of the scientists overseeing the launch of their biggest experiment since NASA sent
02:52men to the moon is Paul Collier.
02:54So it's going to be like a moonshot, where you see Capcom go, go, go, go, go, go, go,
03:02There's going to be a bank of experts saying, my bit's alright, my bit's alright, my bit's
03:05alright.
03:06Probably, yes.
03:07You must get asked this all the time.
03:08Is there a button? Who's going to press it?
03:11There is not at the moment a button, but I'm seriously considering buying one. The LHC
03:15is not like a rocket, there will not be a countdown, there will not be a button to press,
03:21unfortunately. The buttons we have are all computer sequences, which we have to go through
03:27to prepare the machine.
03:31It'll be standing room only here when the world's most eminent particle physicists gather
03:37to watch this remarkable machine spring to life.
03:42What's the scene going to be like on the day that the first beam goes around the LHC?
03:47What's it going to feel like in this control room?
03:50Yeah, it's going to be an interesting time and quite exciting.
03:53The first thing I should say is there will be two people on duty here,
03:57one physicist and one technical engineer.
04:00So if you like, two people will be doing the work
04:02and then probably 200 people will be standing behind watching them work, I hope.
04:07And of course, we'll have to keep control of that.
04:10It's brilliant actually, it's fascinating.
04:13All of us who work at CERN hope that this will become the world's most renowned Big Bang laboratory.
04:22That here we'll discover something so fundamental
04:26that it will change our understanding of the cosmos.
04:31Because right now, even the brightest minds and the best theories
04:36all fall short of explaining what occurred as the universe burst into existence.
04:44Physics is stuck and the only thing left to do is recreate the universe
04:49as it was a fraction of a second after the Big Bang.
04:53And that's what the LHC is designed to do,
04:56to smash bits of matter together at energies never before achieved
05:01so we can stare at the face of creation.
05:13Every civilisation has its own creation story.
05:20The ancient Chinese, Indian mystics and Christian theologians
05:24all place a divine creator at the heart of their creation stories.
05:31Science too has an elaborate story that describes the universe's genesis.
05:39It tells us how the fundamental constituents of the cosmos took on their form.
05:47The difference with this story is that we can test it.
05:51We can find out if it's true by tearing matter apart.
05:55And looking at the pieces.
05:59All you need is a machine powerful enough
06:02to restage the first moments after creation.
06:12In the beginning, there was nothing.
06:15No space, no time, just endless nothing.
06:20Then, 13.7 billion years ago, from nothing...
06:33..came everything.
06:38The universe exploded into existence.
06:46From that fireball of energy,
06:48emerged the simplest building blocks of matter.
07:00Finding experimental evidence of these fundamental entities
07:04has become the holy grail of physics.
07:09Well, the universe is an object that is not stable.
07:13It is expanding and cooling down.
07:16It is doing things.
07:19And it was therefore different in the past,
07:22and it will be different in the future.
07:24It has a history, it has a life, it has an evolution.
07:29As the early universe grew, its mysterious primeval constituents
07:34transformed themselves into atoms, then molecules,
07:38and eventually stars and planets.
07:42Now, billions of years on from the Big Bang,
07:45the universe is so complex that all traces
07:48of the enigmatic building blocks are lost.
07:53Understanding the evolution of the universe
07:56requires understanding what it is made of.
08:01As it turns out, most of that of which the universe is made
08:05are things that we do not understand at all.
08:09But we hope that the LHC is about to bridge this profound gap
08:13in our knowledge by peering further back in time than ever before.
08:23The LHC is truly colossal.
08:27Its accelerator ring is 27 kilometres long,
08:31big enough to encircle a small city.
08:35And around it, we've built four enormous experiments
08:38that will investigate the Big Bang in exquisite new detail.
08:44This is my experiment, the experiment that I work on, Atlas.
08:48And what you can see is just the surface buildings.
08:51The experiment is actually 100 metres below the ground,
08:54which is where the LHC is.
08:56And basically, this is just a building that covers cranes
09:01where we winch everything down.
09:04And this is pretty much the last time that not only TV crews
09:10but me and the people that built it will be able to go down.
09:17Because once it starts operating,
09:19the whole area becomes a radiation area.
09:22It becomes mildly radioactive.
09:26You've always got to be worried when you see those things.
09:34One of the most expensive bits,
09:35if not the most expensive bit of Atlas actually,
09:37was digging the cavern.
09:39We even have Irish scanners, so a little bit of science fiction.
09:52It's down here in caverns brimming with the latest technology
09:55that the Big Bangs will be made.
10:02We just take little bits of matter, little bits of this stuff,
10:07and accelerate them to as close to the speed of light as we can get,
10:11and then smash them together right in the middle of that detector
10:17to recreate the conditions that were present back at the beginning of time.
10:26The bits of matter we're going to fire around the LHC are called protons.
10:32They come from a family of particles that give the collider its name,
10:36the hadrons.
10:38Protons are going to fly around here so close to the speed of light
10:42that they go around this 27-kilometre tunnel 11,000 times a second.
10:49The ring has two barrels that will shoot beams of protons around in opposite directions.
10:58When they collide,
10:59they'll have the energy equivalent to an aircraft carrier steaming at 30 knots.
11:07All this energy will be focused into a space
11:09just a fraction of the width of a human hair.
11:17The resulting explosion will be so intense
11:20that no-one's quite sure what will happen.
11:27This machine really is a leap into the unknown.
11:29I mean, it's often said with scientific experiments,
11:31but I think in this case it's absolutely right.
11:35We're a step, something like a factor of 10 in energy,
11:40so it's a huge jump up in energy.
11:43It's a huge jump up in the number of times
11:45we can smash particles together per second.
11:48It collides protons together so often
11:50that your chances of seeing something incredibly interesting and profound
11:55are increased way beyond anything that we've had before,
11:59and I can think of no better place to be, actually, at the moment.
12:03This is exciting.
12:16The dream of understanding the building blocks
12:19from which the universe is constructed
12:21has inspired the greatest minds for over two millennia.
12:28People have wanted to understand the universe
12:31and the stuff around them ever since they began to think about it.
12:38People have always been making theories about what matter is made of.
12:44But the universe, like everybody else, is made of little pieces
12:48which need to be understood in order to understand how the universe works.
12:53The earliest reference to this concept of the world
12:56being made up of tiny, indivisible pieces
12:59dates back to ancient India in the 6th century BC.
13:05Two centuries on,
13:06the ancient Greeks were the first to call these pieces atoms,
13:10which means uncuttable.
13:13But incredibly, it was only in the early 20th century
13:17that the concept of the solid atom was shattered
13:23and a modern version of atomic theory was born.
13:26This new theory described the atom as being made up
13:29of a number of even smaller pieces.
13:33Around the particles which form the nucleus of the atom,
13:36other electrically charged particles called electrons
13:40constantly revolve like planets around the sun.
13:45This new subatomic theory inspired the great experimental physicist
13:49Ernest Rutherford to invent the art of particle colliding.
13:53And ever since, we've peeled away the atomic layers.
14:00Far from being uncuttable,
14:01the atom appeared to be more and more like a Russian doll.
14:23Today, particle physicists are busy dreaming up
14:26ever more elaborate ways to torture matter.
14:32It almost seems like a paradox
14:34that the smaller the thing you are looking for,
14:37the bigger the instrument you need.
14:44This is Fermilab, and I used to work here for three years.
14:48It's a beautiful piece of midwestern prairie.
14:52The reason I worked here is because over there
14:54is the biggest particle accelerator that's operating in the world today.
15:00I served my apprenticeship on a machine here called the Tevatron.
15:06Under that lake there, there's a tube that carries a beam of protons one way
15:10and antimatter protons the other way.
15:12And we accelerate them round 50,000 times a second.
15:16Imagine that, it's as close to the speed of light as we can get.
15:19And then we smash them together, two places, actually.
15:22That red building there, which is called CDF,
15:24and that blue building over there, which is called D0.
15:27And their job is to just simply take a picture of those collisions.
15:36Fermilab has been colliding particles for over 40 years...
15:42..probing the atom's secrets.
15:50Leading the way into this subatomic frontier
15:53was the renowned particle hunter Leon Lederman.
16:04We didn't know anything about these particles.
16:06We knew about atoms, but we had no idea of the complexity of matter.
16:14What puzzled Lederman was that the more they looked inside the atom,
16:18the more fundamental particles they found.
16:23The moment of discovery is really a series of moments.
16:27The experiment is working, we think it's OK.
16:30And then finally, hey, look at that, there's an event.
16:37Eventually, we get enough data to say we're beginning to see
16:42a class of particles that must have a very important role
16:46in the evolution of the universe.
16:50Because of the work of Lederman and other pioneers,
16:53scores of particles completely new to science emerged.
17:02The up quark, the down quark, the electron, the electron neutrino,
17:07the W plus and the W minus.
17:10As scientists made their discoveries,
17:13they began to name these fundamental particles.
17:16The charm quark, the strange quark, the muon, the mu neutrino.
17:23With these building blocks,
17:24they came to a remarkable understanding of the world.
17:29The top quark, the bottom quark, the tau and the tau neutrino,
17:33the Z particle and the photon.
17:38Now they could explain what anything in the universe
17:41could explain what anything and everything is made of.
17:47That's the standard model.
17:49Oh, no, the gluon.
17:52I'm going to forget the gluon.
17:59The standard model has gone on to become the basis
18:02for all modern particle physics.
18:07So this was a model which was developed in the 1960s,
18:11and the first experimental breakthroughs,
18:14showing that it might be true, came in the 1970s.
18:18And I would say it was really established by experiments
18:23at CERN in the 1980s and the 1990s.
18:27Experimental science has shown that the nature of matter
18:30is more complex than anyone had foreseen.
18:35Rather than a single atom,
18:37it turns out that nature uses 16 different fundamental particles
18:42to make everything we see in the cosmos.
18:47The standard model itself is a triumph.
18:51We have not only the particles,
18:55but the mathematics that gives a huge coherence
19:01to our world on the microscopic level.
19:08The standard model accurately describes
19:11the essential constituents of the universe.
19:16It's no exaggeration to say it's one of the most successful theories
19:20in the history of science.
19:28And yet many physicists feel uneasy about the standard model.
19:33The maths is too complex, even ugly.
19:42When scientists talk about beauty in a physical theory,
19:47they mean that it can describe a whole range of diverse phenomena
19:51with, hopefully, simple concepts and,
19:55in the case of physics, a lot of data.
19:59With, hopefully, simple concepts and simple maths.
20:04Take Einstein's theory of general relativity,
20:07our theory of gravitation.
20:09You can write it down in one line.
20:19Now, the trouble with the standard model is,
20:22well, it takes pages to write down.
20:25But also, there are elements in it that are mysterious, arbitrary even.
20:45There's something spooky about this standard model.
20:49It doesn't really work.
20:51So we know that there's something sick in our theory.
20:56For example, we have at the moment what we call
20:59a standard model of particle physics.
21:01Works great.
21:03Only one small problem.
21:05If you write down the equations of this model,
21:07it would seem to suggest that no particles would have any mass.
21:11Clearly, that's not true.
21:18For all its power, the standard model overlooked one of the most basic,
21:23fundamental properties of our world.
21:27It was incomplete in its description of the universe.
21:38What's missing is an explanation,
21:42a mechanism for how the fundamental particles acquire mass.
21:46Now, we know intuitively that the things in the world around us have mass.
21:53We can feel it.
21:55It's... Well, it's what makes stuff stuff.
21:59But what is mass and why does it exist?
22:04Sounds simple, but it's become one of the most difficult
22:08and challenging problems in physics.
22:18There must have been a time in the early universe
22:21when the particles became substantial and took on their mass.
22:32The best theory we have to explain how this happened
22:35was dreamt up one day by a British physicist, Peter Higgs,
22:39whilst walking in the Scottish Highlands.
22:45He came up with a theoretical mechanism
22:48that could explain how some, but not all, particles attain mass.
22:56The Higgs mechanism works by filling the universe with a field,
23:00the Higgs field.
23:02And by the universe, I don't just mean up there amongst the stars,
23:06I mean here, in front of me and inside of me.
23:10And particles acquire mass by interacting with the Higgs field,
23:14by talking to it.
23:18The theory is that every particle in the universe
23:21is traversing this invisible Higgs field.
23:25And some particles, like the quarks and electrons,
23:29acquire mass as they pass through.
23:34Whereas massless particles, particles like photons,
23:38don't interact with the Higgs field
23:40and they just pass through the universe at the speed of light.
23:49The Higgs brings simplicity and beauty to a nature
23:54which looks too complicated.
23:58It introduces a kind of symmetry and a kind of beauty to nature,
24:03which gives us an understanding of one of the most puzzling features
24:07of this little model I told you about, the Standard Model.
24:12The Higgs field may solve the problem of missing mass
24:15in the Standard Model,
24:17but the only trouble is we haven't been able to detect it yet.
24:23But there is hope, because it's a law of quantum physics
24:27that all fields must have an associated particle.
24:33Now, it's a key prediction of this Higgs theory
24:36that there should be a quantum of this field,
24:39a particle associated with it,
24:41and that's what's called the Higgs boson.
24:43Is there a Higgs particle? And if there is, how does it appear?
24:47How does it come about to simplify our view of the world?
24:51It would be a tremendous discovery.
24:54If we can find this new fundamental particle, the Higgs boson,
24:59then we'll be one step closer to understanding
25:02how the universe came to be the way it is.
25:05No wonder Lederman called it the God particle.
25:08The Higgs mechanism is our best attempt to repair the Standard Model,
25:13but over 40 years after it was first thought of,
25:17the Higgs particle,
25:19the one thing that could prove the theory correct,
25:22hasn't been found.
25:29So the only way to prove the theory correct
25:32is to try and create the God particle.
25:35The only way to prove the theory correct
25:37is to try and create the Higgs boson for an instant
25:41inside a particle collider.
25:49Some thought that Fermilab,
25:51with its powerful Tevatron collider, would have found it.
25:56Fermilab is working day and night, night and day,
26:00building a machine that's ever-increasing in the number of collisions.
26:05But I would say, probabilistically, we won't find it.
26:13Ever since the Higgs particle was dreamt up,
26:16and despite billions of dollars' worth of research,
26:19Fermilab has not seen even a hint that the God particle exists.
26:31So the hunt for the Higgs boson is about to step up a gear at CERN,
26:36where Europe is about to overtake America
26:40in the high-energy particle-hunting race.
26:48Building an instrument capable of recreating the early universe
26:52and finding the massive Higgs boson has taken decades.
26:57We've had to devise new ways of handling uniquely
27:02not one, but the two most powerful proton beams ever created.
27:09There'll be a beam of protons going that way, in that pipe,
27:14at almost the speed of light.
27:16Another beam of protons going that way, in that pipe,
27:19at almost the speed of light.
27:21And they'll cross inside Atlas
27:24and recreate the conditions that were present
27:27just after the beginning of the universe.
27:30Fantastic.
27:32A ring of 9,500 superconducting magnets
27:36has been designed to safely contain and control
27:40the direction of the proton beams.
27:4313,000 amps of current to the magnets.
27:471.9 Kelvin, minus 271 degrees,
27:52which is colder than the space between the galaxies
27:54to cool the magnets down.
27:56And then the two beam pipes.
27:59One there and one there.
28:02All joined up, these magnets make a collider
28:05four times longer than Fermilab's Tevatron.
28:09To put the scale of the experiment in context,
28:12each circuit the protons make is the same distance
28:16as the halfway mark from England to France
28:19along the Channel Tunnel.
28:21And they'll do this 11,000 times a second.
28:35To understand how we hope to transform two tiny protons
28:39into a massive Higgs boson requires the help of a genius.
28:47Einstein's astonishing insight
28:50into the connection between matter and energy
28:53is the engine which drives all particle physics.
28:59His theory used just five characters,
29:02but with them he had shown us the way to a modern form of alchemy.
29:09Einstein's famous equation E equals mc squared,
29:13that basically says that energy and mass are two sides of the same coin.
29:17They're basically the same thing and they're interchangeable.
29:20In this idea, I think Einstein was truly the first.
29:23Mass is just a form of energy.
29:25That was a very deep insight of Einstein.
29:27There's absolutely no question
29:29and there was no precedent for that idea.
29:33One thing we take for granted as particle physicists
29:36is that we can convert energy into mass.
29:38We do it all the time.
29:40That's how the LHC essentially works.
29:42It speeds protons around faster and faster,
29:45gives them more and more energy and then smashes them together.
29:48And the idea is to make new particles like the Higgs boson, for example,
29:52that's many, many tens or even hundreds of times heavier
29:56than the protons that collided to make it.
30:02So Einstein's most famous equation
30:04is at the heart of the hunt for the Higgs particle.
30:08In effect, the Large Hadron Collider is a relativity machine.
30:15When the ultra-high-speed protons smash into one another,
30:19they'll have phenomenal amounts of energy.
30:24Each collision can produce hundreds of new particles.
30:28For a moment, we've created a mini Big Bang.
30:33It's in these events, as they're known,
30:36that we hope for a fleeting moment
30:39that the massive Higgs particle will be seen
30:42for the first time in 13.7 billion years.
30:48These will be the highest energy collisions we've ever made.
30:52It's led some to wonder if we know what we're doing.
31:02One of the wildest speculations
31:05is that the LHC will be capable of creating black holes
31:09that will devour the Earth.
31:13I get page after page of emails saying,
31:17you maniac, you're going to destroy the planet.
31:21What do you say to these people? You must get the same emails.
31:24I've seen that too, but it's what everybody wants to know about
31:27because it's such a cool idea, right?
31:29Here we have LHC, it's looking at the universe at the earliest times.
31:32What if it could make black holes?
31:34Wow, two interesting things happening at the same time.
31:37But personally speaking, I think it's incredibly unlikely.
31:40I mean, it's so unlikely as to the point
31:42that I don't think there's any way they can be made.
31:44Don't forget, people take this very seriously.
31:46When there was this theory that came out that we could make black holes,
31:49CERN took it so seriously that they made this special risk assessment,
31:52you know, really just to make sure
31:54that there wasn't going to be anything untoward happening.
31:57So no-one need worry.
31:59I really, personally speaking, think that there's absolutely no way
32:02we're going to make anything like that.
32:04It's just too strange a theory.
32:06Even if black holes do show up, they will not destroy the Earth.
32:12Much more likely is that the LHC will create Higgs particles,
32:16and we've had to go to extraordinary lengths to be sure of detecting them.
32:22Not one, but four colossal particle detectors
32:25have been installed around the ring
32:27to take pictures of what happens when protons collide.
32:37Early particle detectors also took photographs of similar events.
32:42It's these pictures that first captured
32:45the fundamental particles in the Standard Model.
32:48Here is evidence for a neutrino caught on film.
32:54This was the first glimpse of the W boson at CERN in the 1980s.
33:01And the Z boson's scientific debut.
33:07But the one missing picture,
33:09the one that would go on the wall if we find it,
33:12is the Higgs boson.
33:17The reason it's been so elusive is to do with its mass.
33:22Our theories predict that the Higgs particle is immensely heavy,
33:27and it's a general rule in particle physics
33:30that heavy particles are unstable.
33:33They simply fall apart into lighter particles.
33:37So if the Higgs is a real part of nature,
33:40it would have long ago vanished from the early universe.
33:44And today, even if we manage to recreate the Higgs,
33:48it'll disappear before we can see it.
33:54Instead, we'll be hunting for its decay artefacts,
33:58other Standard Model particles like W and Z bosons,
34:02quarks and muons.
34:06This is a simulation of a single proton-proton collision at the LHC.
34:11It's actually the simulation of the production of a Higgs particle.
34:15Now, the Higgs particle, you don't see, of course.
34:18It just decays in a fraction of a second.
34:21But what you do see is the smoking gun.
34:24In this case, two very clear red tracks.
34:28These two particles here, called muons,
34:31fall straight out to the very edges of the detector.
34:35And if we see, well, not just one collision like this,
34:39but maybe ten, maybe 100, then we'll have discovered the Higgs
34:43and for the first time we'll understand the origin of mass in the universe.
34:52That is, if the experiment works.
34:56Switching on the planet's largest particle collider
35:00is a precious time for everyone.
35:05The sheer magnitude of this complex machine
35:10and the power in the beam
35:12is something that nobody has ever done in the world
35:15and we have to not forget anything important,
35:18that we destroy something.
35:25It takes months to cool each section of the LHC
35:28down to its operating temperature
35:30of less than minus 271 degrees Celsius.
35:34No mean feat, since this is colder than deep space.
35:41And if anything fails,
35:43it'll be a major setback in the search for the Higgs.
35:49It would take us two, three months to repair that part of the machine,
35:53even though it's based on a sector basis,
35:55and it takes enormous time to warm up the whole sector of 3.3 kilometres,
35:59the cryogenic, so there is a lot of time issues involved.
36:03Even one week is too long, so certainly two, three months is very long.
36:07People are waiting for beam, waiting for physics.
36:11We can't afford that.
36:15So CERN's management decided last year
36:17to cancel an engineering run scheduled to test the entire ring.
36:23Instead of beginning slowly with some safe but dull low-energy collisions,
36:28the machine's first run will accelerate particles to high energies straight away.
36:36If it works, this incredible machine,
36:39this vast effort of thousands of scientists and billions of euros,
36:44is certain to change our understanding of the universe.
36:48If the Higgs exists, then it'll be created here,
36:52in the centre of Atlas, over the next few years.
36:56If we don't see it, then it wouldn't help to build a bigger machine
37:00and a bigger accelerator.
37:02It really means that the god particle doesn't exist.
37:12And for some theorists, finding nothing at the centre of the universe
37:16and for other theorists, finding nothing at the LHC
37:20is actually the most exciting prospect.
37:26It can be argued that the most interesting discovery at the LHC
37:30would be that we cannot find the Higgs,
37:34proving practically that it isn't there.
37:37That would mean that we really haven't understood something,
37:41very deeply not understood something.
37:43That's a very good scene for science.
37:45It can sometimes come from the fact that you hit a wall
37:48and you realise that you truly haven't understood anything.
38:00The theorists may long for a revolution,
38:03but most of us are pretty sure
38:05that the Higgs boson is a real part of nature.
38:09What are the chances we're ever going to solve the mystery of mass?
38:33For the first time in a generation,
38:36we stand at a crossroads in physics,
38:39and that's what makes this place so exciting,
38:43because nobody knows what the next steps are
38:47in our quest to understand the universe.
38:50But I'm convinced that this place will show us the way to new physics.
39:07Even if the Higgs boson does turn up at the launch party,
39:11work at the Big Bang Machine won't stop.
39:15Beyond the mystery of mass
39:17lies a much thornier challenge for the standard model,
39:21a puzzle that defeated even Einstein.
39:25The Higgs boson.
39:27The Higgs boson.
39:29The Higgs boson.
39:31The Higgs boson.
39:33A puzzle that defeated even Einstein.
39:46Why does the world appear to obey different rules?
39:50There's the world of the small, the quantum world,
39:54that the standard model explains so well.
39:57And then there's the world of the large,
39:59the world of stars and planets and galaxies.
40:02The standard model has nothing to say about how they interact.
40:10And it's a problem we've yet to solve.
40:27When you want to understand the way the universe has evolved,
40:31so what happened to it straight after it began
40:33and how it got to how it is today,
40:35you've not only got to know about how many galaxies there are,
40:39the way that stars work and the way that planets form.
40:45You've also got to know what the fundamental building blocks
40:48of all those things are and how they interact together.
40:53And in particular, it's not only the stuff that's in the universe,
40:56but the way that stuff talks to other stuff.
40:59It's about the forces.
41:02If these forces didn't act on matter, nothing would happen.
41:07The stars wouldn't shine.
41:09The atoms that make up the planetary bodies would fall apart.
41:16The universe would disintegrate.
41:22It's the forces in the standard model which hold everything together.
41:30There are four forces that we know of in the universe at the moment.
41:33There's a thing called the strong force which sticks nuclei together.
41:37This strong force is what binds the quarks together
41:41to form the nucleus at the heart of the atom.
41:45It's electromagnetism, the kind of quite familiar force to everyone.
41:50This force holds the electrons in orbit around the atomic nucleus.
41:56And the thing called the weak force, which is quite unfamiliar,
41:59but it allows the sun to shine, so it's incredibly important.
42:04The weak force explains why some atoms undergo radioactive decay,
42:09the process which fuels every star in the universe.
42:14But crucially, one force is missing from the standard model.
42:28Gravity.
42:33In the everyday world you and I inhabit, clearly gravity is all around us.
42:39It's what keeps you in your chair at home,
42:42it's what keeps Earth in orbit around the sun,
42:45and it's what holds our galaxy together.
42:57And Einstein too thought gravity was a force.
43:02And Einstein too thought gravity was pretty important.
43:07His general theory of relativity beautifully describes
43:11how every celestial body interacts with every other body through this force.
43:23The universe on the grand scale can be entirely explained
43:27by Einstein's equations.
43:32But there's a problem.
43:38The moment we try to merge general relativity with the standard model,
43:42we encounter immense difficulties.
43:46So immense, in fact, that nobody's been able to work out how to do it.
43:50They're completely incompatible.
43:53The problem is, they're pictures of the same universe.
43:57Something has to be wrong.
44:00The standard model is incredibly powerful
44:03at describing the world of the small, the quantum world.
44:09But as soon as you try to add gravity into the standard model equations,
44:13they break.
44:15Einstein was searching for just one set of equations
44:19that would work on both planets and particles.
44:23Nothing less than a theory of everything.
44:29This was Einstein's greatest failure.
44:32At the smallest distance scales, his theory just falls apart.
44:37It's impossible to understand.
44:39This was Einstein's greatest failure.
44:42At the smallest distance scales, his theory just falls apart.
44:47Einstein spent the last 30 years of his life
44:50trying to rectify the problem, but he never succeeded.
45:0253 years after Einstein's death,
45:05his theory of everything still eludes us.
45:10MUSIC PLAYS
45:17This is CERN's theory corridor.
45:22Inside each room is a theoretical physicist.
45:29And inside the head of each theoretical physicist
45:32is a different conception of our universe.
45:39The first physicist to coin the term a theory of everything
45:43was CERN's John Ellis.
45:48When we talk about a theory of everything,
45:51we mean a theory of the fundamental constituents of matter
45:57and the forces between them.
46:00You can somehow think of it as a sort of cosmic genetic code, right?
46:07In fact, the standard model already you can regard
46:11as being a sort of genetic code
46:13for making up the regular visible matter in the universe.
46:16All the visible matter in the universe
46:18is made up out of the same quarks and electrons and things
46:21that we can measure in the laboratory.
46:24Somehow or other, these things can be combined
46:28in all sorts of ways to make people
46:31as complicated and bizarre as you or me.
46:36The search for this cosmic genetic code
46:39is the ultimate quest for physicists.
46:42We want to finish what Einstein started.
46:50You might wonder why we believe
46:52the baffling complexity of the universe
46:55can ever be reduced to a single theory.
46:58The answer can be found back at the Big Bang.
47:02If we journey back through time, the universe shrinks.
47:07Galaxies disappear and the stars evaporate into gas.
47:17As we draw to within a couple of hundred thousand years of the Big Bang,
47:22the universe becomes opaque.
47:25Eventually, we approach the moment when atoms vanish.
47:32Now things get really strange.
47:36Seconds away from the Big Bang, the atomic nuclei break apart.
47:44The universe is now so small and so hot
47:48that only the naked fundamental parts of it remain.
47:53This is the time of the Higgs.
47:58It's at this time that the LHC will spend most of its working life.
48:06This is what this machine was designed to do,
48:09to open a window onto the time when the Higgs ruled the universe.
48:14It was designed to open a window
48:18Beyond the Higgs, the universe continues to condense.
48:22Eventually, even the fundamental particles of the Standard Model disappear.
48:27We are approaching the moment of the Big Bang itself.
48:31In the interstellar space,
48:33the universe is now so small and so hot
48:36that only the naked fundamental parts of it remain.
48:40This is the time when the LHC will spend most of its working life.
48:46In the instant of creation,
48:48there must have been a time when the universe was nothing more
48:52than a single, unimaginably hot, fantastically small entity.
48:57The entire universe was made of just one thing,
49:01pregnant with possibilities.
49:07Remarkably, we have a highly speculative theory
49:11that attempts to describe this era.
49:14It's called string theory.
49:17In string theory, the concept is that particles,
49:21the objects that exist, are actually vibrations of a single string.
49:25And like the notes of a piano,
49:30they vibrate once or twice or three times
49:33and each note corresponds to a different particle.
49:36So if everything was just the notes that you could play in a piano,
49:40a single piano, maybe a single string,
49:42that would be a very simple idea.
49:44String theory is certainly the best candidate we have
49:47for a theory of everything, which would combine
49:50all the different forces, all the different particles
49:53and make a decent cup of coffee.
49:57These peculiar strings, if they exist,
50:00are our best attempt to understand what might underpin everything.
50:06They're unimaginably small.
50:09They were the first things in the universe.
50:13And they have multiplied to create every particle we see today.
50:27Incredibly, string theory may succeed where the standard model fails.
50:34Because when gravity is added to the standard model,
50:38the equations break down and produce infinities.
50:47These horrendous infinite answers come about, we think,
50:52because we're treating the particles as being tiny little points.
50:56And when you bring these tiny little points together,
51:00the gravitational force becomes incredibly strong
51:03and we don't know how to handle that.
51:09Gravity can become so strong
51:11because point-like particles can get infinitely close together.
51:18And that means that the gravitational force between them
51:22becomes infinitely strong.
51:27Supposing the particles, instead of being tiny little points,
51:31were sort of warm, fuzzy, extended things, right?
51:35Then you could bring them together
51:37and the gravitational force would not blow up in your face.
51:41So maybe that's the answer.
51:43Maybe particles are not actually points,
51:46but they're actually extended objects.
51:48Maybe they're pieces of string.
51:52Strange as it may seem, by imagining a universe made of string,
51:57we have a way of creating the extra space that gravity needs to work.
52:06The extraordinary thing about string theory
52:10is that, for the first time in the history of physics,
52:14it offers a bridge between the two contradictory descriptions
52:19of the world we see today.
52:21The Standard Model of Particle Physics
52:23and Einstein's General Theory of Relativity.
52:26It's a contender for a theory of everything.
52:30What would Einstein have thought of our current attempts
52:34to bring general relativity into the fold?
52:36What would he have thought of string theory?
52:39I think he would have been delighted for a while.
52:44That is to say, he would have been fascinated by the beauty of the theory
52:49till he realised that it didn't have any convincing predictions
52:57that we could check now.
52:59He would be very unhappy about that.
53:02Einstein would have spurned string theory
53:05because, so far, nobody has produced a single prediction
53:09that we can put to the test.
53:12It remains an intriguing but unprovable concept.
53:20This is science at its most esoteric.
53:24It's like philosophy, religion even,
53:29because all it has going for it is beauty.
53:32We have a mathematical description of the first few moments after creation,
53:37but nothing more.
53:40To see far enough back in time to discover a string
53:44would require a collider the size of our galaxy.
53:50For now, the LHC is as large as it gets.
53:55Although perhaps instead of creating a string,
53:58we can search for one of its most remarkable properties.
54:05The original idea was that, OK, if they're not points,
54:08maybe they extend out along some sort of line,
54:11might be a curvy line, like a piece of string.
54:13That's the name of string theory.
54:15In fact, people realised that that's not enough.
54:19If they're going to be extended in one dimension,
54:22they're probably extended in two dimensions,
54:24maybe three dimensions, maybe more dimensions.
54:27So, in fact, string theory nowadays is a bit of the wrong name, right?
54:33And in fact, people nowadays often talk about something called M-theory,
54:37which is supposed to contain this idea
54:40that particles are not just extended in one dimension,
54:43but maybe M for many dimensions.
54:53Multiple dimensions are notoriously difficult to imagine,
54:57let alone detect.
54:59Yet one of the wildest hopes
55:01is that we might just catch sight of an extra dimension at the LHC.
55:08Space has three dimensions, we all know that,
55:11but we think that maybe each point of our space
55:14is actually not a point, but a sort of little sphere
55:18with extra dimensions inside.
55:20And if we could penetrate into these little spheres
55:24at the energies that we are exploring,
55:26maybe we'll find these extra dimensions.
55:29That idea of extra dimensions is very connected with string theory.
55:41If we do detect another dimension at the LHC,
55:44then we'll be able to show that the universe
55:47is at least a place where strings might feel at home.
55:53A universe in which gravity and the other forces
55:56can harmoniously coexist in our mathematics.
56:01We'll be one step closer to completing our story of creation.
56:09This is maybe the most important thing about the LHC.
56:12For a long time now, we've been speculating about string theory,
56:16about extra dimensions,
56:18but we haven't had hard facts to confront them with.
56:25Now, if we find extra dimensions at the LHC,
56:29that would be kind of a hint that string theory might be right,
56:32but it wouldn't be a proof.
56:34It wouldn't be, if you like, a smoking gun for string theory,
56:38but it would encourage us to think that maybe we were on the right track.
56:43It would be a tremendous breakthrough,
56:47but with today's technology,
56:49finding another dimension is highly unlikely.
56:59The LHC will allow us to explore the earliest times in the universe.
57:05Within a few years, it will tell us whether the Higgs boson,
57:10the god particle, really exists.
57:15And it may even tell us that there are extra dimensions in the universe.
57:20This is exploration.
57:23It's a journey to the very edge of our understanding.
57:32Today is the moment.
57:37We don't know what the LHC is going to discover.
57:41We've got all these ideas. They can't all be right.
57:44A lot of them are going to be proved to be wrong.
57:46But if just one of them gets proved to be right,
57:49then it's going to be the most exciting event in my scientific lifetime.
57:57And for me, that's what science at the Large Hadron Collider is all about.
58:03It represents the noblest side of humanity,
58:07our need to know.
58:34NASA Jet Propulsion Laboratory
58:38California Institute of Technology