0:00:07 > 0:00:11There is a strange and mysterious world surrounding us.
0:00:11 > 0:00:15For most of the time it's hidden from our senses.
0:00:15 > 0:00:21I've always loved detective mysteries, and this is really the greatest mystery ever.
0:00:21 > 0:00:26It's one of the simplest and yet most profound questions in science.
0:00:26 > 0:00:31The search to understand the nature of reality.
0:00:31 > 0:00:35But on this quest, common sense is no guide.
0:00:38 > 0:00:43Quantum mechanics says that I can pass through that wall.
0:00:43 > 0:00:46How often will it happen? Very rarely.
0:00:46 > 0:00:49But wait long enough and it will happen.
0:00:51 > 0:00:57Looking for clues has taken scientists to the frontiers of what is possible to know.
0:01:00 > 0:01:02From black holes...
0:01:02 > 0:01:07to the deepest structures of space and time.
0:01:09 > 0:01:15And what they're discovering may change our understanding of reality forever.
0:01:20 > 0:01:23Don't you find this confusing? I find this very confusing.
0:01:23 > 0:01:27It's almost impossible to talk about using ordinary human language.
0:01:28 > 0:01:33This search has attracted some of the finest minds in physics today.
0:01:33 > 0:01:35But be warned.
0:01:35 > 0:01:42Once you've entered their reality, yours may never look the same again.
0:02:01 > 0:02:07Reality, for most us, is familiar, comforting and reliable.
0:02:07 > 0:02:10It all sort of makes sense.
0:02:10 > 0:02:15Trees grow vertically, footballs follow well-known laws of motion
0:02:15 > 0:02:21and all our actions take place reassuringly in just three dimensions of space.
0:02:21 > 0:02:25But physicists see it a little differently.
0:02:25 > 0:02:29Reality is much weirder than it seems.
0:02:29 > 0:02:31I feel like I'm standing still
0:02:31 > 0:02:36but I'm actually zooming at 67,000 miles an hour around the sun.
0:02:36 > 0:02:40I feel kind of solid, but I'm mostly empty space.
0:02:40 > 0:02:46And all this stuff going on here with the game, maybe the flow of time is just an illusion.
0:02:49 > 0:02:55The search to understand reality has led physicists far beyond surface appearances
0:02:55 > 0:02:59to try and uncover its most fundamental laws and structures.
0:02:59 > 0:03:02But when it comes to defining it,
0:03:02 > 0:03:07reality turns out to be very, very elusive.
0:03:07 > 0:03:13Is that it? You're going to ask me, what is reality? Oh, boy.
0:03:13 > 0:03:15- What is reality?- What...?
0:03:15 > 0:03:18HE STAMMERS
0:03:18 > 0:03:21You want something even shorter than what I said? What?
0:03:21 > 0:03:26Reality is the philosophical concept which we attach to something which is real.
0:03:26 > 0:03:28That doesn't help, right?
0:03:29 > 0:03:35I might say reality is the set of things that we know to be the case.
0:03:35 > 0:03:37Like what?
0:03:37 > 0:03:39Like the fact that we're sitting here, talking,
0:03:39 > 0:03:42like the fact that the world is quantum mechanical,
0:03:42 > 0:03:46the fact that the universe has been around for 13.8 billion years,
0:03:46 > 0:03:49the fact it's hard to get a date on Saturday night.
0:03:49 > 0:03:50That's reality.
0:03:56 > 0:04:02There's no escaping the fact that understanding reality is a truly daunting challenge.
0:04:02 > 0:04:05But that hasn't stopped physicists from attempting the impossible,
0:04:05 > 0:04:08trying to find out what it's all made of.
0:04:08 > 0:04:14And for centuries, they've approached this question with a surprisingly simple technique.
0:04:14 > 0:04:17They smash reality to smithereens.
0:04:21 > 0:04:27Welcome to reality HQ, otherwise known as Fermilab,
0:04:27 > 0:04:31a high energy physics laboratory near Chicago.
0:04:33 > 0:04:38This is Professor Jacobo Konigsberg, particle hunter,
0:04:38 > 0:04:43and one of the few people on the planet who can personally claim
0:04:43 > 0:04:47to have helped discover a bit of reality.
0:04:51 > 0:04:59The machine Konigsberg gets to play with every day is the most powerful particle accelerator in America.
0:04:59 > 0:05:01The Tevatron.
0:05:01 > 0:05:05But like everything to do with reality, it's hidden from sight.
0:05:08 > 0:05:12We're looking at the Tevatron,
0:05:12 > 0:05:17the Fermilab proton-antiproton collider.
0:05:17 > 0:05:20It's ten metres underground.
0:05:20 > 0:05:25These are the fields outside Batavia, Illinois.
0:05:25 > 0:05:27Gorgeous day to look at it.
0:05:27 > 0:05:29And as we speak,
0:05:29 > 0:05:36underground you're having about ten million proton-antiproton collisions occurring every second.
0:05:39 > 0:05:41It's been working for 20 years
0:05:41 > 0:05:46and every day we basically push the boundaries of what's known.
0:05:46 > 0:05:51It's the chocolate factory. We love it.
0:05:53 > 0:05:56What goes on beneath these fields in the Tevatron
0:05:56 > 0:06:00are some of the most violent collisions in the universe.
0:06:00 > 0:06:04Deep underground in a four-mile vacuum pipe,
0:06:04 > 0:06:07encased by superconducting magnets,
0:06:07 > 0:06:10they smash together two subatomic particles
0:06:10 > 0:06:14at close to the speed of light.
0:06:14 > 0:06:20Their aim is to find, among the debris of these collisions, the elementary particles of reality.
0:06:20 > 0:06:23Tiny and indestructible.
0:06:23 > 0:06:27But there's just one hitch with this dramatic method.
0:06:27 > 0:06:34When you collide a single proton with a single antiproton and you create this point of energy,
0:06:34 > 0:06:39out of a single collision you can actually generate hundreds of particles,
0:06:39 > 0:06:44hundreds of different particles that one, as a physicist, needs to try to identify.
0:06:46 > 0:06:48Working out which of these are elementary,
0:06:48 > 0:06:53is a problem that's defined particle physics for over 60 years
0:06:53 > 0:06:58and has required an extraordinary coming together of theory and experiment.
0:06:58 > 0:07:01The problem started with atoms,
0:07:01 > 0:07:05once thought to be the only elementary particles.
0:07:05 > 0:07:10When experimenters first broke into them, they discovered even smaller bits inside.
0:07:10 > 0:07:12Electrons and neutrons and protons.
0:07:12 > 0:07:15But when they tried to smash protons up...
0:07:15 > 0:07:19they encountered a different kind of problem.
0:07:19 > 0:07:24Small particles need high energies to wrench them apart,
0:07:24 > 0:07:27which meant building bigger and bigger machines.
0:07:29 > 0:07:36But what came out of these fabulous feats of engineering was a big surprise.
0:07:36 > 0:07:40To the experimenters' delight, the first proton collisions
0:07:40 > 0:07:45produced not just a handful of new particles but hundreds.
0:07:45 > 0:07:48And when it came to identifying them,
0:07:48 > 0:07:50they realised they needed help.
0:07:58 > 0:08:03To work out what was going on, the experimenters turned to theoreticians,
0:08:03 > 0:08:07the maths geniuses who solve physics problems with the pure power of thought.
0:08:09 > 0:08:15This is Professor Frank Wilczek, a Nobel prize-winning theoretical physicist.
0:08:15 > 0:08:20- How are you?- Just fine! I got a collection of whoopie pies...
0:08:20 > 0:08:23He lives in Cambridge, Massachusetts.
0:08:23 > 0:08:30But he comes out to the beautiful countryside of New Hampshire to do his thinking.
0:08:38 > 0:08:43Wilczek is one of the key architects of our current best description of reality,
0:08:43 > 0:08:47the standard model of elementary particles.
0:08:49 > 0:08:54This model is a detailed description of the basic building blocks of matter
0:08:54 > 0:08:56and the forces that bind them.
0:09:04 > 0:09:09- We got you a good selection of fundamental bits of reality. - Yeah, you certainly have!
0:09:13 > 0:09:18When the experiments were actually done, there was a big shock
0:09:18 > 0:09:25because what happened was people found that when they collided two protons really hard together,
0:09:25 > 0:09:31out came totally new and unexpected particles,
0:09:31 > 0:09:36like K mesons, omega baryons pi mesons, electrons,
0:09:36 > 0:09:40neutrinos, other mesons.
0:09:40 > 0:09:45They ran out of names because the Greek alphabet is only so big.
0:09:45 > 0:09:49There were such a bewildering variety of these baryons and mesons
0:09:49 > 0:09:53that together, they became known as the particle zoo.
0:09:53 > 0:09:56A whole new layer of reality had being discovered,
0:09:56 > 0:09:58but the question no-one could answer was,
0:09:58 > 0:10:01which ones were elementary?
0:10:01 > 0:10:03They were discovered experimentally
0:10:03 > 0:10:07with no underlying theoretical understanding of what was happening.
0:10:07 > 0:10:13So the theorists, who wanted to get down to a simple description of nature,
0:10:13 > 0:10:20thought they were ready to almost close the book on the laws of nature, were totally stymied
0:10:20 > 0:10:22and had to go back to the drawing board.
0:10:24 > 0:10:28Faced with having to explain these unexpected particles,
0:10:28 > 0:10:32the theorists tried to come up with a simple and beautiful solution.
0:10:32 > 0:10:34They wondered if the zoo would make sense
0:10:34 > 0:10:39if it were actually combinations of fewer more basic units.
0:10:39 > 0:10:44They called this new set of particles the quarks.
0:10:44 > 0:10:47Altogether, six quarks were described by the theory.
0:10:47 > 0:10:53Up and down quarks, strange and charm, and bottom and top.
0:10:53 > 0:10:56At first, no-one believed they were real.
0:10:56 > 0:10:58Then hints of them began to show up
0:10:58 > 0:11:03and before long, these imaginary particles were actually discovered,
0:11:03 > 0:11:07one by one, until the theory hit a roadblock.
0:11:07 > 0:11:10The top quark was still missing.
0:11:13 > 0:11:17Either they hadn't found it yet or it didn't exist,
0:11:17 > 0:11:19an unthinkable proposition.
0:11:19 > 0:11:25So together, the theorists and the experimenters decided to take a gamble.
0:11:25 > 0:11:29They invested billions of dollars in a new class of accelerator,
0:11:29 > 0:11:33massively more powerful than anything that had gone before.
0:11:38 > 0:11:44By 1990, Jacobo Konigsberg had joined the hunt for the top quark.
0:11:44 > 0:11:48He had at his disposal the biggest toy in particle physics,
0:11:48 > 0:11:53the shiny new Tevatron, and a beautiful theory to guide him.
0:11:53 > 0:11:56All eyes were on Fermilab.
0:11:58 > 0:12:03Jacobo's team were looking for something so small, it had no discernible size.
0:12:03 > 0:12:06They didn't know its mass.
0:12:06 > 0:12:10And if it existed at all, it was extremely rare.
0:12:16 > 0:12:20It was predicted to be the heaviest of the quarks.
0:12:20 > 0:12:26But even if it did turn up, it would only last a trillionth of a trillionth of a second.
0:12:28 > 0:12:32Finding the top quark was really, really very difficult.
0:12:32 > 0:12:38We had to create thousands of billions of those collisions
0:12:38 > 0:12:45in order to finally detect a few dozen of them that produced top quarks.
0:12:45 > 0:12:48As if creating the collisions wasn't hard enough,
0:12:48 > 0:12:51analysing the fleeting fragments of reality they produced
0:12:51 > 0:12:57depended on the perfect performance of the most intricate scientific instruments ever built,
0:12:57 > 0:12:58the collision detectors.
0:12:58 > 0:13:02This is one of the pieces of the detector.
0:13:03 > 0:13:06It's a big chamber
0:13:06 > 0:13:09that has very, very tiny wires running across it,
0:13:09 > 0:13:11it's full of gas,
0:13:11 > 0:13:15and as particles come out of the collision point,
0:13:15 > 0:13:21they leave tiny traces of ions that are picked up by these wires,
0:13:21 > 0:13:25and then you can reconstruct the actual trajectory of each of the particles
0:13:25 > 0:13:28as they emerge from the collision point.
0:13:28 > 0:13:30This helped us tremendously.
0:13:30 > 0:13:32So this is a piece of history
0:13:32 > 0:13:39and we have it here shown as one of the most magnificent pieces of apparatus
0:13:39 > 0:13:42that have helped us to decode reality.
0:13:44 > 0:13:49Jacobo's team searched for the top quark for four years.
0:13:49 > 0:13:52His handwritten diaries record their frustrated ambitions.
0:13:52 > 0:13:58Over six million collisions, but still no top quark.
0:13:58 > 0:14:04Then one day, everyone came together for a meeting.
0:14:04 > 0:14:09This is the room where, after years and years of taking data,
0:14:09 > 0:14:12we finally realised we had discovered a new particle,
0:14:12 > 0:14:14we had discovered the top quark.
0:14:14 > 0:14:18January 21st, 1995.
0:14:23 > 0:14:29The first reaction from the whole room was silence, and then we broke into an applause.
0:14:29 > 0:14:32Everybody was in disbelief
0:14:32 > 0:14:37because it all had come together after so many years of hard work,
0:14:37 > 0:14:40so many years of searches through many accelerators,
0:14:40 > 0:14:45we finally had it here, and we were convinced beyond any doubt
0:14:45 > 0:14:49that this was going to become part of reality.
0:14:49 > 0:14:56The top quark was here to exist, to stay and here to be part of the history of scientific discoveries
0:14:56 > 0:15:03So the feeling was ecstasy - pure ecstasy.
0:15:03 > 0:15:08We all feel, I think, that this is our baby.
0:15:08 > 0:15:15It's the particle that we unveiled and now we're studying and taking care of.
0:15:15 > 0:15:20With the discovery of the top quark Physicists are close to understanding
0:15:20 > 0:15:25one of the greatest mysteries of reality - what it's all made of.
0:15:25 > 0:15:31They've finally tamed the particle zoo into an elegant set of unbreakable bits called
0:15:31 > 0:15:33the Standard Model of Elementary Particles.
0:15:33 > 0:15:37Six quarks, their six electron cousins - the leptons,
0:15:37 > 0:15:40and four particles that carry force.
0:15:40 > 0:15:45Together, these 16 pieces make up the world we see around us.
0:15:50 > 0:15:52It's an amazing achievement
0:15:52 > 0:15:54to have drilled down through the visible world
0:15:54 > 0:15:57to the bottom layer of reality itself.
0:15:57 > 0:16:01But there's a puzzle at the heart of this picture.
0:16:04 > 0:16:10You like the fact that you're seeing it, you like the fact that you can explain how these characters
0:16:10 > 0:16:15interact with each other, and who they are and what their basic properties are.
0:16:15 > 0:16:23But then you don't know why there are so many, you want to think, what drives those numbers?
0:16:23 > 0:16:29What's so magical about six quarks? What's so magical about six leptons? Why six?
0:16:29 > 0:16:33Every time in history where we've had a really complicated description of reality,
0:16:33 > 0:16:37someone has come along and unified this into something beautifully elegant.
0:16:37 > 0:16:42And right now I think our best understanding of physics, again,
0:16:42 > 0:16:47is just a bit too complicated to be the real deal.
0:16:49 > 0:16:54While particle physicists dream of simplicity,
0:16:54 > 0:16:57there's a whole other branch of physics that questions
0:16:57 > 0:17:02whether reality as we know it can even be said to exist at all.
0:17:08 > 0:17:13Welcome to the weird world of quantum reality...
0:17:16 > 0:17:21..where nothing is quite as it seems.
0:17:21 > 0:17:25Here, in Vienna, experimental physicist Anton Zeilinger
0:17:25 > 0:17:31is about to unlock the mysteries of the quantum world.
0:17:31 > 0:17:38He's going to perform a remarkable experiment that puts the very existence of reality into question.
0:17:50 > 0:17:55Known to physicists as the double-slit experiment,
0:17:55 > 0:18:01it's remarkable because it reveals two astonishing paradoxes about the nature of reality
0:18:01 > 0:18:04That no-one can fully explain.
0:18:04 > 0:18:07I'm now showing you the two-slit experiment
0:18:07 > 0:18:12which contains one of the basic mysteries of quantum mechanics.
0:18:12 > 0:18:13It is very simple.
0:18:13 > 0:18:17We have a laser, we have a two-slit assembly
0:18:17 > 0:18:23where the light can only go through two slit openings and we have an observation screen.
0:18:24 > 0:18:29The experiment has one crucial feature - Zeilinger can control his laser beam so that it fires
0:18:29 > 0:18:35single particles of light, called photons, through the slits.
0:18:35 > 0:18:37Just single particles.
0:18:37 > 0:18:43Lets do the experiment with a camera that's able to detect individual photons.
0:18:43 > 0:18:46We have to cover it now because of the background light.
0:18:46 > 0:18:47Sven, can you help me?
0:18:49 > 0:18:56As the laser fires single photons, some will pass through the slits, some will bounce off.
0:18:56 > 0:18:58Gradually, a pattern will emerge.
0:18:58 > 0:19:03Now you see the photons arrive one by one at the camera.
0:19:03 > 0:19:06Here's one, here's one, here's one.
0:19:06 > 0:19:09So they really behave as mini bullets.
0:19:09 > 0:19:13What would you expect them to do at the double-slit setup?
0:19:13 > 0:19:16You would expect some of them going through this slit,
0:19:16 > 0:19:19some going through this slit, so we would expect two stripes,
0:19:21 > 0:19:25But what you get is something completely different.
0:19:36 > 0:19:39Even though only single photons of light are being fired through the slits,
0:19:39 > 0:19:46they don't create two lines. They mysteriously create three.
0:19:49 > 0:19:53According to physics, this pattern of multiple stripes is what you get
0:19:53 > 0:19:55when you shine a beam of light at the two slits.
0:19:55 > 0:19:59Because when it's a beam, light behaves like a wave,
0:19:59 > 0:20:04creating a classic pattern of light and dark stripes
0:20:04 > 0:20:11But it's totally incomprehensible how SINGLE particles of light can create this wave pattern.
0:20:11 > 0:20:14There's a contradiction here.
0:20:14 > 0:20:21On the one hand, we have individual particles which can go through one slit only at a time.
0:20:21 > 0:20:29On the other hand, we have the stripes which indicate they are waves which go through both slits.
0:20:29 > 0:20:33How can something go through one slit and both slits at the same time?
0:20:35 > 0:20:40The idea that a single particle of light can somehow split in two
0:20:40 > 0:20:43and go through both slits at once
0:20:43 > 0:20:46goes against all the laws of nature that we know.
0:20:50 > 0:20:57From a basic intuitive point of view, this is not possible to understand
0:20:57 > 0:21:02if you stick to a picture of reality as we are used to in everyday life.
0:21:05 > 0:21:12Over the last two decades, Zeilinger and his colleagues have tested quantum theory to its limits.
0:21:12 > 0:21:19They've even proved that it's not just photons that behave strangely, but atoms and molecules, too.
0:21:24 > 0:21:29You might ask, why can't we observe quantum reality?
0:21:29 > 0:21:31But this is where things gets even more weird.
0:21:33 > 0:21:39If you put detectors by the slits, the mysterious behaviour stops.
0:21:39 > 0:21:42The photons behave just like bullets.
0:21:42 > 0:21:44Take the detectors away...
0:21:44 > 0:21:47the multiple stripes mysteriously reappear.
0:21:47 > 0:21:49What's going on?
0:21:49 > 0:21:53Rather astonishingly, it seems that we can change the way reality behaves...
0:21:53 > 0:21:55just by looking at it.
0:21:55 > 0:22:00But this also means that reality has a secret life of its own.
0:22:02 > 0:22:06We know what the particle is doing at the source when it is created.
0:22:06 > 0:22:10We know what it is doing at the detector, when it's registered,
0:22:10 > 0:22:13but we do not know what it is doing in between.
0:22:13 > 0:22:19We cannot describe that with our everyday language.
0:22:21 > 0:22:27If you're finding this hard to get your head round, don't worry - you're in good company.
0:22:27 > 0:22:33The paradoxes of quantum theory drove even Albert Einstein to despair.
0:22:33 > 0:22:37There's a famous story from the history of physics.
0:22:37 > 0:22:41One day, Albert Einstein
0:22:41 > 0:22:44asked his friend, Niels Bohr, a Danish physicist,
0:22:44 > 0:22:49"Do you really believe the moon is not there, when nobody looks?"
0:22:52 > 0:22:58Bohr's answer was, "Can you prove to me the opposite?
0:22:58 > 0:23:03"Can you prove to me that the moon is there when nobody looks?" This is not possible.
0:23:12 > 0:23:18For more than 70 years, physicists have debated what quantum theory means for reality.
0:23:18 > 0:23:23Zeilinger's detective work may yet lead us to an answer.
0:23:26 > 0:23:32Quantum physics is an exciting theory because it is extremely precise,
0:23:32 > 0:23:35it is mathematically beautiful and it describes everything.
0:23:35 > 0:23:37It just doesn't make sense.
0:23:41 > 0:23:46So reality turns out to be stranger than we ever imagined.
0:23:48 > 0:23:52Everything has the power to be in two places at once.
0:23:52 > 0:23:54But we'll never see it.
0:23:54 > 0:23:56It's all very peculiar.
0:23:56 > 0:24:00You'd be wrong to think you can ignore it, because quantum reality
0:24:00 > 0:24:04might be about to change our lives in a big way.
0:24:15 > 0:24:22Here at MIT is a physicist who sees, in reality's strange behaviour,
0:24:22 > 0:24:25enormous power and opportunity.
0:24:25 > 0:24:28Seth Lloyd is aiming to revolutionise our lives,
0:24:28 > 0:24:34with a new class of computers, like nothing the world has ever seen.
0:24:40 > 0:24:44This is a quantum computer. It actually happens to be
0:24:44 > 0:24:48the best and most powerful quantum computer of its kind in the world.
0:24:48 > 0:24:52It runs on superconducting circuits that are cooled to within
0:24:52 > 0:24:55a few thousands of a degree of absolute zero.
0:24:56 > 0:25:00And it contains in its guts a little tiny bit
0:25:00 > 0:25:04where a current going round like this represents a zero,
0:25:04 > 0:25:07and a current going like that represents a one
0:25:07 > 0:25:11and a current going both directions at once is zero and one.
0:25:11 > 0:25:14And that's what's going on in here at the moment.
0:25:15 > 0:25:22Whereas a normal computer bit can only represent a zero or a one, a quantum computer bit can be zero
0:25:22 > 0:25:25AND one at the same time.
0:25:25 > 0:25:27Link these multi-tasking bits together
0:25:27 > 0:25:34and they can do vast numbers of calculations simultaneously, opening up new worlds of possibility.
0:25:34 > 0:25:39Quantum mechanics is weird and quantum computers use quantum weirdness
0:25:39 > 0:25:45to process information in ways that ordinary classical computers could never even comprehend of doing.
0:25:45 > 0:25:51As a result, even a tiny quantum computer with a few hundred quantum bits in it could be more powerful
0:25:51 > 0:25:54than a classical computer the size of the whole universe.
0:25:57 > 0:26:03What's unique and impressive about Seth's engineering of the quantum world
0:26:03 > 0:26:06is that, for the first time ever,
0:26:06 > 0:26:13he's opening up a line of communication between our reality and quantum reality.
0:26:13 > 0:26:18Quantum bits are very small, really teeny, cannot see it with the naked eye,
0:26:18 > 0:26:20cannot see it through a microscope.
0:26:20 > 0:26:27But you need this whole roomful of equipment to tickle this quantum bit and get information
0:26:27 > 0:26:34from our human scale down to this extremely microscopic scale where quantum bits actually live.
0:26:34 > 0:26:38If you talk to them just right, and massage them
0:26:38 > 0:26:43till they're happy enough, then you can get them to do what you want.
0:26:44 > 0:26:46Sounds easy
0:26:46 > 0:26:50but Seth has to overcome the most mysterious rule of reality -
0:26:50 > 0:26:55the fact that his quantum bits stop being able to do two things at once
0:26:55 > 0:26:57as soon as he tries to observe them.
0:26:57 > 0:27:02The quantumness of reality is apparently very sensitive.
0:27:02 > 0:27:06This is actually one of the main problems with building large-scale quantum computers
0:27:06 > 0:27:10because it doesn't take just me or you to look at something and make the computer fail,
0:27:10 > 0:27:14it can just be some passing electron wandering around,
0:27:14 > 0:27:18bounces off this little superconducting loop and says WHOA!
0:27:18 > 0:27:23The electrons in there are going around like that, that's enough to mess up your quantum computation.
0:27:26 > 0:27:31Seth clearly faces some of the most difficult technical challenges science has ever known.
0:27:31 > 0:27:32That's going up again.
0:27:32 > 0:27:38But if he overcomes them, quantum computing has a huge potential to change our world.
0:27:38 > 0:27:39It's very real.
0:27:41 > 0:27:43My favourite use for quantum computers
0:27:43 > 0:27:46is to use them to understand the weird features of the universe.
0:27:46 > 0:27:49Classical computers - lets face it - they kind of think the way we do,
0:27:49 > 0:27:51they're not so good for understanding quantum mechanics.
0:27:53 > 0:28:00If we're ever really to understand how this quantum universe works at bottom, we need quantum computers
0:28:00 > 0:28:05to serve as our intuition, for understanding the fundamental workings of the universe.
0:28:11 > 0:28:16Seth's computer depends on things being in two places at once for its power...
0:28:18 > 0:28:22..but there's a growing number of physicists who don't believe that
0:28:22 > 0:28:25this is what reality is really like at all.
0:28:27 > 0:28:31They think the answer to this puzzle lies beyond our universe.
0:28:33 > 0:28:37Just checking to see whether reality is still there.
0:28:37 > 0:28:42Max Tegmark is a cosmologist. He's studied the greatest mysteries
0:28:42 > 0:28:45of the universe, from the big bang to black holes.
0:28:45 > 0:28:48When it comes to explaining how reality works,
0:28:48 > 0:28:54he draws his inspiration from one of the most bewildering ideas in cosmology...
0:28:54 > 0:28:55parallel worlds.
0:28:55 > 0:29:01This theory says that beyond the edges of our universe
0:29:01 > 0:29:05there are an infinite number of other universes.
0:29:05 > 0:29:08It sounds like the stuff of science fiction...
0:29:08 > 0:29:12that there's another you living more than a trillion trillion light years away.
0:29:12 > 0:29:15But it's not the only version of this theory.
0:29:16 > 0:29:22Max thinks that parallel worlds don't just exist beyond our universe.
0:29:22 > 0:29:27They're here, millimetres away. And they're being created all the time.
0:29:27 > 0:29:29I'm here right now
0:29:29 > 0:29:30but there are many, many different
0:29:30 > 0:29:34Maxes in parallel universes doing completely different things.
0:29:34 > 0:29:38Some branched off from this universe very recently
0:29:38 > 0:29:41and might look exactly the same except they've put on a different shirt.
0:29:41 > 0:29:47Other Maxes may have never moved to the US in the first place or never been born.
0:29:47 > 0:29:52This vision of reality says that any time we go to work,
0:29:52 > 0:29:57there'll be another universe where we stay at home.
0:29:57 > 0:30:00There are universes where we all have different careers.
0:30:03 > 0:30:08There are also universes where we don't even exist.
0:30:08 > 0:30:12It's a disturbing idea, developed in the 1950s,
0:30:12 > 0:30:19but for Max, it's the best and only solution to the paradox at the heart of quantum reality.
0:30:19 > 0:30:22The big problem with quantum mechanics is that the little
0:30:22 > 0:30:27particles that we're all made of can be in multiple places at once,
0:30:27 > 0:30:33yet I'm made of little particles and you never see me in two places at once, so what's going on here?
0:30:35 > 0:30:42Max thinks that the maths of quantum theory is telling us something remarkable.
0:30:42 > 0:30:45So whenever the equations say that this tennis ball is in
0:30:45 > 0:30:48many different places at once, what that really means is that
0:30:48 > 0:30:55our reality is branched out into multiple universes and in each one, the ball's in a definite place.
0:30:57 > 0:31:02According to this theory, when the photon of light faces two slits...
0:31:02 > 0:31:04it doesn't split in two.
0:31:04 > 0:31:05It splits the world in two.
0:31:05 > 0:31:13Every photon in the double slit experiment creates a new parallel world...
0:31:13 > 0:31:17..which means what we think of as reality is just one
0:31:17 > 0:31:23of an infinite number of realities, each one slightly different from the next.
0:31:30 > 0:31:33However strange this theory sounds,
0:31:33 > 0:31:37Max believes you have to accept reality as you find it.
0:31:39 > 0:31:44Like if I get a parking ticket, there's always a parallel universe where I didn't.
0:31:44 > 0:31:49On the other hand, there's yet another universe where my car was stolen,
0:31:49 > 0:31:51so you win some, you lose some. But seriously...
0:31:51 > 0:31:58my job as a scientist isn't to tell the universe how to conform to my preconceptions of how it should be,
0:31:58 > 0:32:01but to look at the universe and find out how it really works.
0:32:04 > 0:32:08It seems that whatever our senses are telling us about reality,
0:32:08 > 0:32:12we only get to experience a fraction of what's really going on.
0:32:16 > 0:32:20Take it as it comes, you know - we've been humiliated before by the vast universe,
0:32:20 > 0:32:25since Copernicus, since the discovery of the distant galaxies,
0:32:25 > 0:32:29the Big Bang, and, er, this is a dis... this is another
0:32:29 > 0:32:37sort of humiliation where... er, we're finding that our thought... our ordinary, er, sensing
0:32:37 > 0:32:45of the world is so very, very partial, we only see tiny averages of this very rich structure.
0:32:49 > 0:32:55Quantum reality is about the strangest discovery that physics has ever made.
0:32:55 > 0:32:58But it's also fantastically powerful.
0:32:58 > 0:33:05Not only has it helped to create our modern computer age but it's helped us understand all kinds of phenomena
0:33:05 > 0:33:10from the shining of stars, to the colour of gold.
0:33:10 > 0:33:16It's changed our relationship to reality forever, philosophically and practically.
0:33:16 > 0:33:20But that relationship might be about to change again.
0:33:23 > 0:33:28In the last few decades, an astonishing new idea has been taking shape.
0:33:28 > 0:33:31An extraordinary vision of what reality might be
0:33:31 > 0:33:36that combines every field of physics from quantum to the Big Bang.
0:33:36 > 0:33:43If it's true, it will trigger a bigger change in thinking about reality than anything we've seen.
0:33:43 > 0:33:47And it all began one day in San Francisco.
0:34:05 > 0:34:11Professor Lenny Susskind is one of America's most eminent theoretical physicists.
0:34:13 > 0:34:20Back in 1981, he was developing a theory about how matter was made out of strings,
0:34:20 > 0:34:25when a local entrepreneur asked him to host a small, private science conference.
0:34:25 > 0:34:29Susskind invited a British cosmologist to give a talk.
0:34:30 > 0:34:35It was Stephen Hawking, and the lecture he gave about black holes
0:34:35 > 0:34:37was to change the course of Lenny's life.
0:34:54 > 0:35:00That's where Stephen dropped the bombshell that left us so confused for 20 years.
0:35:04 > 0:35:10At the time, Stephen Hawking was the pre-eminent scholar working on black holes.
0:35:10 > 0:35:16He'd achieved amazing insights into the inner workings of these mysterious objects.
0:35:18 > 0:35:22Black holes are the most terrifying places in the universe.
0:35:24 > 0:35:30Created when a giant star dies, at their dark hearts is a point of infinite gravity,
0:35:30 > 0:35:35so powerful, nothing can escape it - not even light.
0:35:40 > 0:35:44Lenny was expecting to learn something interesting about black holes.
0:35:44 > 0:35:52What he didn't expect was for Hawking's new theory to challenge everything he knew about reality.
0:35:53 > 0:35:56I had absolutely no idea at the time
0:35:56 > 0:36:00that this was going to change my life for the next 20 years.
0:36:02 > 0:36:12Stephen began to talk about black holes and told us a story which seemed so crazy and so strange.
0:36:12 > 0:36:16It seemed absolutely wildly impossible - that black holes
0:36:16 > 0:36:19would violate all the principles of physics that we knew.
0:36:21 > 0:36:26Hawking's revelation was that black holes, instead of lasting forever, as everyone thought,
0:36:27 > 0:36:28eventually disappear,
0:36:28 > 0:36:31leaving no trace of anything,
0:36:31 > 0:36:39including something physicists consider a fundamental part of reality - information.
0:36:39 > 0:36:43If information was lost in ordinary circumstances in this room, that would be bad,
0:36:43 > 0:36:45because then all kinds
0:36:45 > 0:36:49of weird stuff would start happening, like,
0:36:49 > 0:36:53the hour of time could start going backwards,
0:36:53 > 0:36:58you know, clocks might not work, we all might disappear like that.
0:36:58 > 0:37:03The fact that information is conserved in ordinary physics, is at the very basics of physical law.
0:37:03 > 0:37:10Today information is as important a part of reality as matter and energy.
0:37:10 > 0:37:14Everything physical contains information.
0:37:14 > 0:37:20It's the description of what something is - its colour, its mass, its location.
0:37:20 > 0:37:26And crucially, like energy, information can never be destroyed.
0:37:30 > 0:37:36I just knew, or felt, deep in my gut, that Stephen had to be wrong.
0:37:40 > 0:37:47That lecture set me on a mission, you bet, and that mission was to reconcile the two
0:37:47 > 0:37:50competing and conflicting points of view about black holes -
0:37:50 > 0:37:58that they eat information and evaporate but information is not allowed to be lost.
0:38:01 > 0:38:07As Lenny drove home that night, he knew his first task was to learn as much about his subject
0:38:07 > 0:38:13as possible - mysterious and terrifying black holes.
0:38:17 > 0:38:22Every black hole has a boundary known as the event horizon.
0:38:22 > 0:38:24It's the point of no return.
0:38:24 > 0:38:29If you pass it, you'll never escape the black hole's gravitational pull.
0:38:29 > 0:38:32If you get too close to a black hole,
0:38:32 > 0:38:35you're done. If you get sucked into it,
0:38:35 > 0:38:41nothing can come out, not even your screams, not even your...
0:38:41 > 0:38:44radio transmission for help, nothing.
0:38:46 > 0:38:49If anything passes the event horizon,
0:38:49 > 0:38:51it takes its information with it.
0:38:51 > 0:38:55Lenny had to find some way for black holes to evaporate
0:38:55 > 0:38:58without destroying the information inside them.
0:38:58 > 0:39:05But the physics of black holes is so complicated that he wrestled with the problem for the next 12 years.
0:39:14 > 0:39:20Then in 1993, one fine day in Stanford, Lenny wandered into the physics department
0:39:20 > 0:39:27and saw something that gave him an amazing insight into what the true nature of reality might be.
0:39:32 > 0:39:34The insight...
0:39:34 > 0:39:39to what became known as the Holographic Principle simply happened one day
0:39:39 > 0:39:44when I was walking in the physics department and came upon a hologram.
0:39:46 > 0:39:50Well, when I saw the hologram it occurred to me that there's
0:39:50 > 0:39:53a very big difference between a hologram and an ordinary picture.
0:39:53 > 0:39:59When you see a hologram you can look around it and you can see what's behind the lady's head there.
0:39:59 > 0:40:04Not just the surface, but you can see what's behind her,
0:40:04 > 0:40:07there's a sense in which it's really capturing three-dimensionality.
0:40:07 > 0:40:10It was capturing the full three-dimensional
0:40:10 > 0:40:16structure of the room and everything behind her, so when I passed it by,
0:40:16 > 0:40:23almost jokingly I said to myself, maybe the horizon of a black hole is something like a hologram.
0:40:23 > 0:40:26The stuff that falls into the black hole is three-dimensional.
0:40:26 > 0:40:29The stuff of the horizon is two-dimensional.
0:40:29 > 0:40:33But maybe in some way, the stuff of the horizon is like a hologram,
0:40:33 > 0:40:37capturing the full three- dimensionality of the things that fell into the black hole.
0:40:40 > 0:40:45Holograms are created from information encoded on a flat surface.
0:40:45 > 0:40:49Lenny realised that if black holes were like holograms,
0:40:49 > 0:40:54then there's only one place where their information could be stored - the event horizon,
0:40:54 > 0:41:00which would mean it would never fall in and it would never be destroyed.
0:41:02 > 0:41:06Not only did Lenny's insight help save information from black holes,
0:41:06 > 0:41:11but it lead to a new mathematical tool, called the holographic principle,
0:41:11 > 0:41:18that says all three-dimensional objects can be encoded in only two dimensions.
0:41:18 > 0:41:24The holographic principle has morphed from a wild speculative almost crackpot idea.
0:41:24 > 0:41:30Complete consensus has formed around it.
0:41:30 > 0:41:34It is almost completely accepted across theoretical physics.
0:41:34 > 0:41:41It has gone from being a wild idea to being an everyday tool of theoretical physics.
0:41:45 > 0:41:47But Lenny didn't stop there.
0:41:47 > 0:41:51He and other physicists made a truly shocking leap of the imagination.
0:41:51 > 0:41:56They asked - what if the whole of reality is a hologram?
0:41:56 > 0:41:59Projected from our own event horizon -
0:41:59 > 0:42:02the far edges of the universe.
0:42:02 > 0:42:08Maybe the real information in the world is not where it seems to be.
0:42:08 > 0:42:13Maybe it's way out far away at the boundaries of the universe
0:42:13 > 0:42:17and that it's completely wrong to think that things fall into black holes,
0:42:17 > 0:42:23rather the black hole and things that fell into them are really holograms,
0:42:23 > 0:42:27or really images of things taking place very, very far away.
0:42:36 > 0:42:41If Lenny is right and the ultimate nature of reality is holographic,
0:42:41 > 0:42:47it would mean our three dimensions are an illusion,
0:42:47 > 0:42:53that we're being projected from information that's stored at the outer reaches of our universe.
0:42:53 > 0:42:55It's an incredible vision...
0:42:55 > 0:43:00but if you think you understand it, you probably don't.
0:43:05 > 0:43:07OK, I think I'm getting it, so that...
0:43:07 > 0:43:09Don't think you're getting it, cos you're not getting it
0:43:09 > 0:43:12and the reason you're not getting it is because nobody get it.
0:43:13 > 0:43:16There are some times when we...
0:43:16 > 0:43:20It's like quantum mechanics - nobody understands quantum mechanics.
0:43:20 > 0:43:27We know how to use it and we know how to make predictions of it, but nobody has their heads around it.
0:43:28 > 0:43:34It seems utterly bizarre that the ultimate nature of reality might be holographic.
0:43:34 > 0:43:38That at the edge of our universe, there might be a shimmering sheet
0:43:38 > 0:43:43of information that describes the entire universe within,
0:43:43 > 0:43:47including you and me and everyone we know.
0:43:51 > 0:43:57But incredibly, this theory is about to be put to the test.
0:43:57 > 0:44:03We maybe on the brink of finding out that the world is a hologram.
0:44:06 > 0:44:08Back at Fermilab,
0:44:08 > 0:44:12a unique million dollar experiment is just beginning.
0:44:12 > 0:44:19Expert technicians are building an extraordinary machine they call the holometer.
0:44:20 > 0:44:26Designed to be so sensitive, it can measure the smallest units of space and time.
0:44:26 > 0:44:30It's the brain-child of Professor Craig Hogan,
0:44:30 > 0:44:34the Director of the Centre for Particle Astrophysics at Fermilab,
0:44:34 > 0:44:41who became intrigued by an unexplained sound, recorded by scientists in Germany.
0:44:41 > 0:44:43WHITE NOISE
0:44:49 > 0:44:56This recording is noise picked up by a gravitational wave detector.
0:44:56 > 0:44:58But it's not gravitational waves.
0:44:59 > 0:45:06Hogan thinks that buried within it might be the sound of holographic reality.
0:45:06 > 0:45:10So he's designed an experiment to test his theory.
0:45:18 > 0:45:21Hogan's holometer will bounce beams of light between mirrors,
0:45:21 > 0:45:24timing how long the beams take to return.
0:45:24 > 0:45:30It will be able to detect infinitesimally small delays, or as he calls it -
0:45:30 > 0:45:33fuzziness in space and time.
0:45:33 > 0:45:36So this is one of the beam tubes of our holometer.
0:45:36 > 0:45:41It's a six inch steel pipe and we're going to bolt them together
0:45:41 > 0:45:43in one big tube, 40 metres long
0:45:43 > 0:45:45and do that five different times
0:45:45 > 0:45:48and the laser light's going to go down the centre of the tube.
0:45:48 > 0:45:51So before we do that, we have to clean them out
0:45:51 > 0:45:55cos the optics are super precise, need to be kept super clean.
0:45:55 > 0:45:59Right now, they're cleaning out the end station,
0:45:59 > 0:46:01this is this sardine-can like object,
0:46:01 > 0:46:06it's where the business guts of the holometer are going to be.
0:46:06 > 0:46:13It's where the mirrors and so on that are doing the precise measurement are going to be.
0:46:13 > 0:46:18Ultimately, this machine might tells us that space time is sitting still.
0:46:18 > 0:46:24If the light goes out the two arms and comes back at exactly the same time and there's no extra jitter
0:46:24 > 0:46:27then that's a classical space time,
0:46:27 > 0:46:30but it could be that we'll find a little bit of air or fuzziness
0:46:30 > 0:46:35in there and that would be the clue that we live inside a hologram.
0:46:37 > 0:46:40Craig thinks that if reality really is holographic
0:46:40 > 0:46:44then the closer you look at it, the more insubstantial it will be,
0:46:44 > 0:46:47like a photograph
0:46:47 > 0:46:52enlarged over and over again.
0:46:52 > 0:46:57This fuzziness will disturb his laser beam and that's the evidence he's looking for.
0:46:57 > 0:47:01Well, it's very exciting to actually be building a machine with this kind of
0:47:01 > 0:47:05precision to be able to do this, you know, we're measuring
0:47:05 > 0:47:11the arrival time of wave fronts of light to a very small fraction the size of an atomic nucleus.
0:47:11 > 0:47:15And timing those pulses to microsecond accuracy.
0:47:15 > 0:47:18Nobody's ever done that before, nobody's ever tested to see
0:47:18 > 0:47:21whether space time actually stands still at that level.
0:47:23 > 0:47:27If Craig Hogan proves that reality is holographic,
0:47:27 > 0:47:31it will be one of the most important discoveries in physics.
0:47:31 > 0:47:37It may cause as big a change in thinking as the revelations of quantum theory.
0:47:37 > 0:47:42But if there's one thing that stands out about all the theories used,
0:47:42 > 0:47:44to probe and explore reality today,
0:47:44 > 0:47:52it's this - their best and most perfect expression is not in words, it's in maths.
0:47:52 > 0:47:58The connection between mathematics and reality is a miracle, but it works.
0:47:58 > 0:48:02It's actually unreasonable how well mathematics works,
0:48:02 > 0:48:05why should the world behave according to mathematical laws?
0:48:05 > 0:48:10It is not only that it becomes easier to describe with mathematics
0:48:10 > 0:48:13as you go deeper and deeper into reality,
0:48:13 > 0:48:18mathematics becomes the only way to describe reality.
0:48:20 > 0:48:27If our most detailed knowledge of reality, from fundamental particles to ripples in space time,
0:48:27 > 0:48:29is really best described in maths,
0:48:29 > 0:48:35could it be that the ultimate definition of reality is staring us in the face?
0:48:46 > 0:48:52Cosmologist Max Tegmark seems to be fond of radical explanations of reality
0:48:52 > 0:48:55and it's no different when it comes to maths.
0:48:55 > 0:48:59Instead of just accepting mathematical order in the world,
0:48:59 > 0:49:05he's been trying to figure out why it exists and where it comes from.
0:49:05 > 0:49:07He thinks he has a solution.
0:49:21 > 0:49:24To me, maths is the window on the universe.
0:49:24 > 0:49:29It's the master key to understanding what's out there.
0:49:30 > 0:49:34I wouldn't say I'm completely monogamous with equations,
0:49:34 > 0:49:36but there are just a very few I love the most.
0:49:40 > 0:49:44I love them because they describe exactly what's going on
0:49:44 > 0:49:46outside the window in our universe.
0:49:49 > 0:49:51These equations describe how light behaves.
0:49:53 > 0:49:56This equation describes how gravity behaves.
0:49:58 > 0:50:03This equations describes how atoms behave.
0:50:03 > 0:50:07These equations describe what happens when you go really fast near the speed of light
0:50:09 > 0:50:13And it's just amazing to me that a little bit of scribbles like this
0:50:13 > 0:50:19can capture the essence of what's going on in this very complicated looking universe out there.
0:50:19 > 0:50:23Galileo way back in the renaissance already remarked that nature seems
0:50:23 > 0:50:26to be a book written in the language of mathematics.
0:50:26 > 0:50:27This all came after Galileo,
0:50:27 > 0:50:30so why are we discovering even more and more
0:50:30 > 0:50:34mathematical regularities out there, what is it telling us?
0:50:38 > 0:50:42I think the universe isn't just described by math...
0:50:42 > 0:50:44I think it is math.
0:50:44 > 0:50:50I think our entire universe is a giant mathematical structure that we are a part of.
0:50:50 > 0:50:54And that, that's the reason why the more we study physics
0:50:54 > 0:50:57the more mathematical regularities we keep discovering.
0:50:58 > 0:51:04Max's theory pushes at the edges of physics and into the realm of philosophy,
0:51:04 > 0:51:07conjuring up the oldest question of all -
0:51:07 > 0:51:11what is real?
0:51:11 > 0:51:15I think the universe is a mathematical object, it's just out there,
0:51:15 > 0:51:17existing,
0:51:17 > 0:51:21in a sort of platonic sense, it's not that it's existing inside
0:51:21 > 0:51:26of space, and time, but space and time exists inside of it.
0:51:26 > 0:51:30And that really changes our perspective of it and that
0:51:30 > 0:51:34really means that reality is very different from how it seems.
0:51:35 > 0:51:39If Max is right, maths isn't a language we've invented,
0:51:39 > 0:51:44but a deep structure we're gradually uncovering like archaeologists.
0:51:44 > 0:51:49An abstract, unchanging entity that has no beginning and no end.
0:51:49 > 0:51:53As we peel back the layers, we're discovering the code.
0:51:53 > 0:51:57Strange as it seems, it's a comforting theory
0:51:57 > 0:52:00because if reality is a mathematical object,
0:52:00 > 0:52:03understanding it might be within our reach.
0:52:04 > 0:52:08If I'm wrong, it means fundamental physics is going to eventually hit a roadblock
0:52:08 > 0:52:12beyond which we can't understand reality any better.
0:52:12 > 0:52:17If I'm right, then there is no roadblock
0:52:17 > 0:52:21and everything is, in principle, understandable to us.
0:52:21 > 0:52:27And I think that will be wonderful because we'll only be limited by our own imagination.
0:52:28 > 0:52:34These two grand visions of reality - the mathematical structure and the cosmic hologram,
0:52:34 > 0:52:39represent theoretical thinking at its most imaginative and beautiful.
0:52:39 > 0:52:44They may lead us towards a bright future or they may end up being discarded
0:52:44 > 0:52:50because as all physicists know, nothing becomes real without being put to the test.
0:52:56 > 0:53:02Few know this more acutely than the scientists at Fermilab.
0:53:03 > 0:53:08Right now they're engaged in the greatest race of modern physics -
0:53:08 > 0:53:12trying to find a bit of reality that's been missing for 40 years.
0:53:12 > 0:53:19It's the most important particle of all - the Higgs Boson.
0:53:19 > 0:53:24Nobody really understands the origin of mass and the Higgs particle
0:53:24 > 0:53:28was introduced to explain why different particles
0:53:28 > 0:53:30have different masses.
0:53:30 > 0:53:35So, it is important because it answers one of the most fundamental unknowns
0:53:35 > 0:53:42in reality, in particle physics, mass makes reality and we don't know where it comes from.
0:53:44 > 0:53:49It's round-the-clock work, and people running computer codes,
0:53:49 > 0:53:52sifting through the data, finding new ways of looking for
0:53:52 > 0:53:57the Higgs because you can get incredibly creative.
0:53:57 > 0:54:03In fact, this is one of the things that happens here, that you start doing the easy analysis,
0:54:03 > 0:54:07the easy way to look for things and as it gets harder, you get more and more creative...
0:54:09 > 0:54:12The Higgs is now Fermilab's number one priority,
0:54:12 > 0:54:15but they aren't the only ones looking for it.
0:54:15 > 0:54:16They have competition...
0:54:19 > 0:54:24..from the biggest particle accelerator of them all -
0:54:24 > 0:54:26the Large Hadron Collider in Geneva.
0:54:26 > 0:54:30It's more than three times as powerful.
0:54:30 > 0:54:35So it may yet be the one that discovers the Higgs first.
0:54:37 > 0:54:41Meanwhile, the Tevatron continues its ten million collisions a day.
0:54:44 > 0:54:47I feel really proud of this machine.
0:54:47 > 0:54:50It's been a beauty of an instrument for many years
0:54:50 > 0:54:57and hopefully it will help us find unveil one more secret of reality in the very near future.
0:54:58 > 0:55:02Billions of dollars have been poured into this quest
0:55:02 > 0:55:06and thousands of physicists around the world are looking for the Higgs Boson,
0:55:06 > 0:55:08but it's still theoretical.
0:55:08 > 0:55:10What if we don't find it?
0:55:12 > 0:55:15OK, so if we don't find anything that has the properties
0:55:15 > 0:55:18that are expected of this Higgs Boson
0:55:18 > 0:55:22or some combination of things that can do the job,
0:55:22 > 0:55:27we'll really, really, really have to rethink a lot of what we thought we knew...
0:55:32 > 0:55:36That won't happen, we'll find something!
0:55:42 > 0:55:48It may be that we are standing on the verge of a new version of reality.
0:55:52 > 0:55:55We have these clues, quantum mechanics, relativity,
0:55:55 > 0:55:58the holographic principle, a few others,
0:55:58 > 0:56:01and it's just waiting around for somebody to really
0:56:01 > 0:56:05put it together into, what does it really say about reality?
0:56:10 > 0:56:17Physicists have redefined reality by close measurement and observation of the material world.
0:56:17 > 0:56:22They've drilled down to the bottom layer,
0:56:22 > 0:56:26discovered that we can change reality just by looking at it...
0:56:29 > 0:56:35..and begun to sense that information encoded at the edge of our universe,
0:56:35 > 0:56:37could be more important than matter.
0:56:41 > 0:56:45But in the end, reality is perhaps best defined
0:56:45 > 0:56:50as an intelligent conversation with the universe,
0:56:50 > 0:56:55that will continue as long as we're around to ask questions.
0:56:57 > 0:57:02It's human nature to keep asking questions,
0:57:02 > 0:57:06it's fun and it's challenging and it's what makes us human.
0:57:06 > 0:57:14If there is an ultimate version of reality, I think it's a long way before we get there...
0:57:14 > 0:57:17so I don't want to be part of that.
0:57:17 > 0:57:21I would guess that there are limits to what we can understand,
0:57:21 > 0:57:25but old people always think there are limits to what we can understand,
0:57:25 > 0:57:29it's the young people who push past those limits.
0:57:29 > 0:57:34MUSIC: "Is That All There Is" by Peggy Lee
0:57:57 > 0:58:01Subtitles by Red Bee Media Ltd
0:58:01 > 0:58:05E-mail subtitling@bbc.co.uk