"In 1988, I wrote a popular science book called A Brief History Of Time, which sold over ten million copies." "I say that not to brag, but to underline the deep fascination we all have with our universe." "20 years ago, people rushed to buy Stephen Hawking's book." "It was an unlikely sensational best seller, and he became an instant celebrity." "In the book, he promised we would soon have the ultimate answer - a theory of everything that explained how the universe began." "But 20 years on, it remains tantalisingly elusive, and Hawking's body is deteriorating." "Now his only way of communicating is through one muscle in his cheek." "For Hawking, time is running out to unlock the mysteries that could finally make him master of the universe." "These films are a journey into his extraordinary quest for a theory of everything." "He does not see himself as a genius." "He sees himself as one of those lucky people who get paid to do what they love." "It's just that his job is a little bit different from most people's." "20 years ago, Hawking said he wanted to know the mind of God." "He felt he was on the brink of delivering a simple, elegant set of laws that would explain everything in our universe and, more importantly, how it all began." "How can we understand the universe?" "Is it arbitrary or is there a grand design?" "Do we still need a God?" "20 years on, my need to find answers to the fundamental questions about our existence is undiminished." "Hawking's need to find answers started early." "He was born in 1942, during the darkest days of World War II." "Hawking has always enjoyed the fact that he was born 300 years to the day after the death of that other revolutionary scientist, Galileo." "As a schoolboy, he was gifted and enquiring." "His father hoped he'd study medicine." "He chose physics." "But in 1963, while studying for his PhD, he was told he had a life-threatening disease." "His response to the bad news was later made much of in the press." "How true is it that when you were first diagnosed, that you listened to Wagner and drank heavily?" "I took to listening to Wagner, but reports in magazine articles that I drank heavily are an exaggeration." "The trouble is, once one article said it, other articles copied it, because it made a good story." "The outlook was bleak." "Motor neurone disease is progressive." "The nerves controlling the muscles degenerate to complete paralysis, while the brain remains intact." "He was given two years to live." "Before then, as a student," "Hawking had, by his own admission, become somewhat directionless." "Now faced with an uncertain and nightmarish future, he developed a fierce determination that would become his hallmark." "Often to the exclusion of all else, he set his sights on the greatest questions in physics." "Professor Bernard Carr was a graduate student of Hawking's, and became his close colleague." "And of course it's required a huge amount of effort for him... ..but in some sense" "I think it's given Stephen the determination to overcome the problems and it made him even more determined, I think, to crack the ultimate problems of physics." "So young Hawking set off to crack the ultimate problem of physics." "He wanted to get an idea of what the beginning of the universe looked like." "But to do that, he'd have to attempt what everyone else thought was impossible." "Hawking was going to have to unify the two great, but very different, theories of physics." "Einstein's theory of relativity is the theory of the very large." "Of planets, galaxies and space." "Quantum mechanics is the theory of the very small." "Of atoms, particles and forces." "But to understand how the universe came about," "Hawking would have to force the two together." "My life's work has been to unify the theories of the very large and the very small." "Only then can we answer the more challenging questions." "Why are we here?" "And where did we come from?" "It's a quest that, despite near total paralysis, he's not about to give up on." "He's a very tenacious, courageous individual, but he never thinks of it like that, he just gets on with it." "That's really how he gets on with everything." "He can be quite exhausting as well, you know, very demanding." "He doesn't get tired like the rest of us." "We all get very tired, but he can keep going." "Physicists love to explain how our universe arose and how it works." "We understand enormous amounts, but when asked, "How did it all come to be?" ", we don't have one single answer yet"" "Can I have a minute, please?" "Stephen Hawking is the Lucasian Professor of Mathematics at Cambridge University, a post once held by Sir Isaac Newton." "Age 66, Hawking still tirelessly puts in a full week of teaching and research." "Hawking's schedule is frantic." "As well as trying to find out how our universe came about, he tries to satisfy an incessant demand for his illustrated lectures." "Can you hear me?" "(ALL) Yes." "According to the Boshongo people of Central Africa, in the beginning there was only darkness, water and the great god Bumba." "One day Bumba, in pain from a stomach ache, vomited up the sun." "The sun dried up some of the water, leaving land." "Still in pain, Bumba vomited up the moon, the stars and then some animals - the leopard, the crocodile, the turtle and finally, man." "This creation myth, like many others, tries to answer the questions we all ask." "Why are we here?" "Where did we come from?" ""Why are we here?"" "was a question Hawking asked himself a lot back in 1965, while contemplating what the doctors had told him might well be a very short life ahead." "Then he heard reports of a lecture given in London by a brilliant young mathematician, Roger Penrose." "Sorry to interrupt but Roger Penrose is here." "I was wondering, shall I bring him up?" "Yes." "Thank you, Stephen." "Penrose's ground-breaking work catapulted Hawking out of his depression." "I certainly remember Stephen in lectures asking extremely awkward questions at the ends of seminars, or in the course of seminars - that was the thing that struck me particularly about him." "They were penetrating questions I should say, not just awkward." "Penrose had given Hawking a glimpse of how physics could be used to answer the question," ""Why are we here?"" "For both Penrose and Hawking, the starting point was Einstein's Theory of Relativity." "The theory of the very large." "It explains how the universe works, and how insignificant our place in it is." "One small planet in a tiny galaxy, lost in the vast realms of space, as cosmologist Pedro Ferreira explains..." "Now, let's imagine that this enormous library is our visible universe, and we know that the universe is sprinkled with galaxies - and I really mean sprinkled - there's a lot of empty space around each galaxy." "Let's take our galaxy, the Milky Way." "It would comfortably fit in a full stop in Stephen's book." "Our galaxy is microscopic compared to the gigantic tracks of empty space that dominate the universe." "But Einstein showed that all that empty space turns out to have some remarkable properties." "Let's imagine that this basketball is a celestial object like a star," "OK, and let's imagine that this book shelf with these books is space." "In our classical view of space, it would be rigid like this, it would just be this static thing, this thing that is unresponsive, but in our modern view, this star as it moves through space," "it warps it, it dents it, it bends it, and other objects that then move through this space will feel this warp, will feel these bends, these warps and will move according to that." "They won't move in straight lines, they'll feel these bends and they'll curve." "The fact that big objects like stars can actually bend and curve space, is now an everyday notion to astrophysicists like Kim Weaver." "What we're talking about in terms of astronomy and cosmology are objects that have a huge amount of mass - a planet, a planet-sized object or a moon-sized object or a star-sized object." "The mass of this object bends space around it." "If the ball here that is at the centre of this sheet is representing the sun, and this penny is representing a planet like the earth, then you can use the penny to demonstrate how the earth orbits the sun." "Most of us think of gravity as an invisible force, which holds us on the earth and keeps the earth in orbit round the sun." "So far, so good." "But what physics says is really happening is that planets are trapped in areas of curved space." "The earth is actually rolling round and down into an area of space warped by the sun." "The penny rolls in quickly, but of course it'll take the earth billions of years to hit the sun." "And it's the curvature of space caused by the earth itself which holds us in place on our planet." "Hawking knew Einstein's work like the back of his hand, but what excited him was that Penrose had used the theory to discover something altogether bizarre." "It was possible not just to bend space, but to twist it right back in on itself, to create a black hole." "Penrose showed that when a massive star burns out, it collapses in on itself in a spectacular way." "Something that was many times bigger than our sun is compressed to a size smaller than an atom." "It becomes so incredibly dense that it pulls space back towards it." "Everything in that warped space is eaten up." "Even light cannot escape its clutches." "Around the ultra-dense centre, there forms a sphere of darkness, that we now call a black hole." "But Penrose hadn't just shown that a massive star could collapse into a black hole." "What gripped Hawking was that Penrose had proved, using Einstein¡¯s equations, that at the very centre of a black hole, there had to be a plughole, down which matter, space and time disappeared." "The plughole had a fancy mathematical name - a singularity." "Hawking was excited and mystified." "In 1965," "Roger Penrose showed that if a star collapsed below a certain critical radius, it would inevitably develop a singularity, at which time would come to an end." "At first I didn't understand either the significance or the proof of this result." "Hawking became obsessed with understanding the singularity." "It was a poignant choice of specialist subject." "A young man who'd been told he had two years to live was wrestling with a point in space where the universe disappeared out of existence." "This was typical of Hawking's stubbornness, refusing to accept the limitations of his body, or his brilliant mind." "And even in his private life, he exhibited the same bravado." "Despite his family's concerns over his health, he met, fell in love with, and married Jane Wilde, a languages student." "As Jane later remembered in an interview, death seemed to be all around." "It was the time of the Cold War with Russia, an age of defiance." "It wasn't a terribly difficult decision to take, to marry Stephen, because I think a lot of people had forgotten that, at that time, every day, one read reports in the newspapers that a nuclear war was likely to break out in the next year or two." "People said they weren't going to have children because there was going to be a nuclear war, and the fact that Stephen had been diagnosed as only having a couple of years to live didn't really seem to be very much different to the situation" "that was facing the rest of us, anyhow." "But out of this gloom, Hawking managed to conjure up... light." "Out of what seemed to be the end of everything, he found a beginning." "Penrose had shown that bits of the universe could be sucked into a singularity, a tiny plughole at the centre of a black hole." "Hawking took Penrose's equations and reversed them." "Like running a film backwards." "Where Penrose showed the universe disappearing into a black hole," "Hawking showed it came from one." "For thousands of years, man had wondered how the universe began." "Now, a young PhD student from Cambridge had come up with an answer." "It was an incredible turning point in our understanding of the world." "But Hawking's results raised as many questions as they solved." "He could prove the universe started from a tiny, single point, but frustratingly, not how or why." "It seemed to many that this inexplicable, sudden appearance of the universe, expanding out from a microscopically tiny point, had to be a miracle." "There are two attitudes one can take from the results of Penrose and myself." "One is that God chose how the universe began for reasons we could not understand." "At a conference on cosmology in the Vatican, the Pope told the delegates that it was OK to study the universe after it began." "But they should not enquire into the beginning itself, because that was the moment of Creation and the work of God." "I was glad he didn't realise I had presented a paper at the conference suggesting how the universe began." "I didn't fancy the thought of being handed over to the Inquisition like Galileo." "LAUGHTER" "APPLAUSE" "Hawking's response to his results was to decide that the equations he'd used," "Einstein's Theory of Relativity, were not the whole story." "General relativity makes a prediction that the universe was once infinitely small, but it loses the ability to describe the universe when it was tiny." "Hawking now knew that our entire universe did start out as a tiny dot, but he wasn't going to be happy until he could describe how that dot came about." "Hawking had lain down a huge challenge for himself and the rest of physics." "As physicist Michio Kaku explains." ""The bottom line is," "Einstein's equations are useless at the instant of the Big Bang." "We physicists say that a long time ago, the universe was so small it was smaller than a basketball, you could put the universe in your pocket, it was smaller than an electron." "Some people call it a "singularity of infinite gravity"." "Now, that's silly." "There's no such thing as infinite gravity, it just means that we use the word "singularity" to hide our ignorance." "We don't know what this singularity is." "Unraveling this singularity, this tiny point of creation, became Hawking's life's work." "(MOUTHS)" "But it was a race against time, against encroaching disability." "Hawking has defied all the predictions of his doctors, his disease has progressed much more slowly than they thought it would." "But today, he has only the use of his facial muscles." ""He communicates, actually using just one muscle on his cheek." "There's a little censor, and whenever he moves his cheek, that sends a pulse through to his computer." "By tensing that one muscle, he can do everything from checking his e-mail, to speaking, to browsing the internet." "I was there with him when he changed from using the finger switch on to the blink switch, and it was quite a..." "Well, the blinks which sat in a cupboard for 13 years before he would even think of trying it, so he tends to go with what he knows." "Every time he changes to another type of technology, he seems to see that as admitting defeat." "So, he's very resistant to changing to other technologies." "Can you finish in 10 minutes?" "10 minutes?" "15." "Maybe!" "It becomes very apparent that his struggle is daily, it's not just something that he gets used to, then it's not a problem any more." "At the same time, you realise how much help he's got." "You know..." "That doesn't mean it's easy for him." "But Hawking is nothing if not determined, and back in the 1970s, he set his sights on solving the big problem - what happened at the moment of Creation?" "In the early 1970s, black holes were the agents of death, the place where everything we know about the cosmos came to a chilling end." "But to a young physics researcher like Stephen Hawking, they were an exciting challenge." "He'd already shown that the universe arose from a single, tiny point now he wanted a complete theory of everything." "A theory that would describe the moment of universe's creation in precise detail, and again, black holes would point the way." "My own work on black holes began with a Eureka!" "moment while getting into bed in 1970." "In 1970, getting into bed was a protracted business for Hawking." "His paralysis was increasing and he needed constant care and attention from his wife, Jane." "And they'd started a family." "But despite his disability, the couple were managing." "He'd taken a research post at Cambridge University and was eagerly pursuing his quest to understand the universe." "What Hawking had glimpsed that night getting into bed was something very peculiar about black holes." "Hawking knew that every object in the universe could be heated up or cooled down, but black holes were different." "Heat, would never get out of a black hole, it seemed." "This started to niggle Hawking, but it would turn out to be the key to the mystery of creation." "Hawking was about to attempt something no other physicist had ever achieved." "For 50 years physicists had failed to unite the theories of the very big and the very small." "Einstein's theory of gravity would not fuse with the very different theory of how atoms work - quantum mechanics." "But what Hawking had glimpsed was a point where the two must clash - at the very edge of a black hole." "What happens if you have a black hole which is sitting there, it's black, that's why it's called a black hole, no light comes out of it." "What happens if you include the effects of quantum mechanics?" "Einstein's theory said the black hole was a smooth, perfect sphere." "Hawking plunged it into a sea of particles and atoms." "The two theories sputtered and fought each other." "Somehow, Hawking must bring them together." "The problem of reconciling Einstein's theory with quantum mechanics is one of the holy grails of modern physics." "What Hawking did in the early '70s was, he didn't try to solve this problem completely," "but he tried to put quantum mechanics and general relativity together in a very limited fashion." "What was all the more remarkable was that now unable to write down long equations and calculations," "Hawking had to imagine the whole process in his head." "As well as space and black holes," "Hawking had to visualise a world we are all unfamiliar with, the bizarre realm of the very small, of the atom." "A good way to think of an atom is a bit like our solar system." "You've got a nucleus at the centre and electrons whizzing around." "Now, let's imagine that this marble is the nucleus of an atom." "An electron will be the width of this hair." "Now again, we're used to seeing in textbooks that an electron is more or less this distance from a marble, but it's not, it's not this far, it's not this far." "It's not this far..." "It's not even this far..." "Not even here." "On this scale, where the nucleus is the size of a marble and an electron is the width of a hair, the electron would actually be two miles away from the nucleus." "At the atomic level, particles are almost not there." "They're less like solid lumps of matter and more like tiny empty force fields, and as force fields, they shimmer." "Physicists often describe them as waves." "Water, sound and light can behave like waves, but so too can the parts of the atom and that means they can spread out to be in more than just one place at a time." "Common sense says that when I fire this gun, one ball hits one target, that's it." "If this is an electron gun hitting many targets," "I find out that one electron has a probability of hitting many targets at the same time." "Now, that violates common sense." "I thought it was one ball, one target." "In the quantum world, common sense is violated." "Common sense has no place in the quantum world." "Hawking knew that atoms were not like little billiard balls." "They turn out to be much more fuzzy and erratic." "How could he join Einstein's stars and planets that float sedately along nice curved lines, with atoms that buzz around in a frenzy?" "At a very tiny level, our universe is like a crazy dance of waves jangling to a myriad of beats." "Particles appear and disappear at random, and at this level nothing is certain, not even existence." "Atoms are a bit like people." "They're very hard to predict with absolute certainty." "They do roughly what you'd expect of them, but never exactly." "With atoms, it's even hard to be totally certain whether they exist or not." "Sometimes, Hawking knew, atoms pop up where there should be absolutely nothing around." "In fact, out in space, it happens all the time." "The theory of the very tiny says space is never empty." "At an atomic level, there is always a tiny, tiny amount of activity." "But the theory of the very big says nothing exists at the edge of a black hole." "Hawking realised this was where the two theories clashed." "He had to find out what was really going on." "According to the theory of the very tiny, in empty space, there are pairs of subatomic particles that emerge out of the void, exist for a tiny moment and then destroy each other." "And so the idea is that out of nothing if you like, a pair of particles is created and then exists for a short time and then annihilates, and that's happening throughout space, so it's happening there and it's happening there" "and it's happening there." "This pair of particles is like yin and yang, night and day, opposites that would not exist without each other." "One has positive mass and the other has negative mass." "But Hawking asked, what would happen if this pair of particles bumped up against a black hole?" "Hawking realised that the positive particle would have just enough energy to escape the black hole, but the particle with negative mass would fall in" "and it would do something extraordinary to the black hole." "The particle that goes inside the black hole eventually decreases the mass of the black hole." "It effectively has negative mass." "But the particle that goes off to the distant observer, is there observed as part of radiation." "Although we now understand why black holes have to give off thermal radiation, it came as a complete surprise at the time." "At first I thought I must have made a mistake." "But Hawking had not made a mistake." "Around a black hole is an almost imperceptible microscopic glow." "Positive mass particles fly off from it, behaving just like heat." "Negative mass particles fall in." "Slowly, almost imperceptibly, they decrease the mass of the black hole and this eventually has catastrophic consequences." "So what the Hawking result implies, it means that the black hole, instead of being black, is actually always emitting radiation." "What is happening is that for most of its life, the black hole is gently sizzling away, but eventually it gets smaller and smaller, the temperature gets hotter and hotter and eventually it gets to a point where it's so hot" "that it essentially explodes, it loses all the rest of its mass in a very, very short time." "Hawking had transformed the black hole from a ball of nothing into a galactic monster, that chews up the universe and spits out fire and brimstone." "When black holes were first thought of and when I first started studying black holes," "I remember thinking, "Oh, a black hole, it's the end of everything, a star collapses down and everything disappears into it and nothing ever comes out, so maybe it's really boring?"" "But really, black holes represent our best way to have an ultimate test of the physics of understanding the universe." "And astronomy has borne out Hawking's discovery." "Black holes now seem to be where it all happens." "They're the engines that rip up the cosmos and create new stars and jets of energy and matter." ""Black holes are not ultimate end points, they really are beginnings of something - around a black hole you have enormous amounts of activity going on." "You have stars being ripped apart and you have discs of accreting matter swirling around, you have cauldrons of heat and light around a black hole, you have jets being produced by a black hole." "You have particles coming out at half the speed of light, being shot away from a black hole, you have stars being born around a black hole." "There's an enormous amount of stuff going on caused by the fact that that black hole's really there, and that's exciting." "Hawking had taken a great leap forward in his quest." "He'd linked the theories of the big and the small for the first time ever in physics." "What was really amazing about this paper, really one of the most beautiful papers in the 20th century, is that his argument that this could happen relies on almost no assumptions." "The assumptions about the nature of quantum mechanics and the nature of general relativity, that basically every living physicist will agree with." "But Hawking had done more than just show that black holes were complex." "The theory of the very tiny was starting to unlock the secrets of the very large." "Could he now apply it to the entire universe?" "Could he now explain the big bang?" "By applying quantum mechanics to the edge of the black holes in the 1970s," "I was able to revolutionise our understanding of them." "To expand our understanding further, we need to bring quantum mechanics into the heart of the black hole." "In the 1970s, it seemed Hawking had only to wrest the key to the universe from the inner reaches of his brilliant mind." "But more humble problems of health, love and fame would try to tempt him away from his devotion to physics." "This world that is so familiar, how did it come about?" "Can we ever discover how all this came to be?" "Stephen Hawking runs a department that is still trying to find the answer." "He has his PhD students and they have supervision, and they come in every week and have lunch, and they talk about ideas, and if they get stuck, they can come to him." "You have to have exceptionally good students to be able to cope with the heavy work that they have to have, and also with the communication, they really have to know their subject." "You have all survived the summer." "LAUGHTER" "Very well." "Start" "Aged 66, when many are retiring," "Hawking shows no sign of giving up his quest." "The food's improved!" "Has it improved the work-rate of the students?" "No!" "I think he caught you there!" "Hawking's life's work has been to come up with a theory of everything, a theory that explains how our universe works and how it arose." "In the 1970s, he had huge success using the theory of the tiny, quantum mechanics, to better explain black holes." "But in the 30 years since, using it to explain the entire universe has turned out to be just a bit harder." "Hawking has admitted that he was over-confident." "The early 1960s idealism of his work and his personal life have waned somewhat." "His relationship with his family was often strained by his drive to succeed." "His wife Jane, interviewed in 1989, said despite her dedication, she struggled to cope with someone whose whole focus was physics." "His determination has now rather outstripped mine." "I cannot keep up with him." "I do think he tends to overcompensate for his condition by doing absolutely everything that comes to his notice." "I'm not a scientist." "I'm not an appendage of Stephen, as I very much feel I am." "When we go to some of these official gatherings, I mean, sometimes I'm not even introduced to people." "Hawking's dedication to his science came with a personal cost." "By 1985, just before his meteoric rise to fame, the Hawkings' marriage was under considerable strain, and the couple were drifting apart." "Jane took her family on holiday, while Hawking went on a working trip to Switzerland alone." "But as he was visiting the huge particle accelerator at CERN, near Geneva," "Hawking suddenly contracted severe pneumonia." "It seemed he might not make it." "Jane rushed to his side." "For days, he struggled on life support." "But with characteristic stubbornness, Hawking pulled through." "He'd needed a tracheostomy, which meant he completely lost his ability to speak unaided." "The famous voice box followed soon after." "Then came the book." "Through it all," "Hawking's eye was, and still is, on the prize." "The theory of everything." "Nevertheless, even though the job has been more difficult than one might have hoped," "I think there is still every indication that there is a final theory and that we may get there, but it just proves much more complicated than we originally hoped." "It is, after all, the toughest job in science." "Hawking's trying to peer back to 13.7 billion years ago, to the start of everything." "His main stumbling block has been getting the theory to explain what the entire universe was like back then, when it was all compressed to a size smaller than an atom." "Although the universe is very big now, the observable universe is something like 13,000 million light years, the distance light has travelled since the Big Bang, we know that that entire region must once have been compressed into a very, very small scale." "But, of course, once the universe is compressed into a very small scale or a very high density, we know we are in the domain of quantum theory." "Using the theory of the tiny," "Hawking has made huge progress in describing the birth of the universe." "But there is one part that eludes him." "He's found it impossible so far to describe how gravity must have worked at the moment of the Big Bang." "If we want to know what happened when the universe began, we have to have a theory that can describe gravity on a very small scale." "For the last 30 years," "Hawking has struggled to find a way to describe gravity with quantum theory, but he has unshakeable faith that the theory of the tiny will eventually win through." "And he's not alone." "Today all of physics is racing along beside him." "Incredible experiments are now being built in outer space and deep underground, which will try to probe deeper into the very moment of creation." "There is excitement in the air, a sense that the problem of gravity in the early universe will be solved, and that a theory of everything is just waiting to be found." "Whether he finds it first or not," "Hawking is philosophical about his part in this great journey." "I was unlucky to get motor neurone disease, but lucky in almost everything else." "I have three very attractive children, success in my scientific work and a real sense of satisfaction at having achieved all of this, despite the difficulties." "Not many people can say this." "Is there anything you wish you'd achieved professionally that you haven't already?" "I feel I have achieved quite a lot, but one would always like to have done more." "In particular, I would like to have found a complete theory of quantum gravity in the early universe." "Still, that wouldn't have left much for anyone else to do." "Subtitles by Red Bee Media Ltd" "Stephen Hawking wants big answers to big questions." "How can we understand the universe?" "Is it arbitrary, or is there a grand design?" "Do we still need a God?" "In 1988," "Stephen Hawking wrote an unlikely but sensational bestseller and became an instant celebrity." "In the book, he promised we'd soon have the ultimate answer, a Theory of Everything, that explained how the universe began." "This film tells the story of what happened next," "Hawking's 20-year struggle to fulfill his dream, and the extraordinary events of his personal life." "Today, almost completely paralysed," "Hawking is tantalisingly close to his goal." "It seems that he and his fellow physicists may be about to discover the secret of the universe's beginning." "Stephen Hawking's record-breaking, bestselling book," "A Brief History Of Time, has made him an international celebrity." "But time is precious to a man who clicks out sentences at three words a minute." "Hawking was diagnosed with motor neurone disease in 1963, when he was a PhD student." "Doctors gave him two years to live." "For 40 years, he's defied their predictions." "With a string of major discoveries to his name, he's become the world's most famous scientist." "But being a celebrity can have its drawbacks." "This is our fans." "Professor Hawking's fans." "Huge, incredible piles of mail." "Their imaginations are extremely interesting." "Um..." "You get people who write in about time wormholes, about spacecraft, alien invaders, teleporting." "How can Professor Hawking possibly comment on all these theories?" "It's not possible." "But we do try and interest some of the students sometimes." "Slowly, word by word, click by click," "Hawking continues towards a complete theory of the fundamental processes of our cosmos - his Theory of Everything." "His focus now is the very moment of creation, the birth of our universe." "But to crack that involves making sense of the least understood force in nature." "My recent experience of weightlessness demonstrates how well we understand gravity on the human scale." "But we must understand gravity as it affects individual particles." "Stephen Hawking is like a cosmic crime scene investigator." "He's trying to understand something that happened 13.7 billion years ago" " the Big Bang." "He's turning over all the remnants of the explosion and trying to fit them back together again." "The fragments are all the matter and forces of nature we see around us today." "But one piece refuses to fit." "Gravity." "As human beings, we don't notice anything strange about gravity." "But if it had been any stronger, the universe as we know it could never have existed." "Space would have been pulled back in on itself, obliterating any possibility for planets and stars to form." "There are four forces in nature, and gravity seems to be strangely weaker than the other three, as physicist Michio Kaku explains." "We see four fundamental forces of the universe today." "Gravity, which holds the Earth, the sun and the solar system together, the electromagnetic force which lights up our cities and the internet and laser beams, and also the two nuclear forces." "But why should there be four fundamental forces?" "We think that at the instant of creation, these four forces meld together into a single force, a super force." "At the Big Bang, everything was one." "But as the universe cooled, four forces emerged." "Electromagnetism and the two nuclear forces which controlled atoms and radioactivity all seemed to be about the same strength." "But the fourth force, gravity, isn't just a bit weaker... ..it's vastly weaker." "As Professor Lisa Randall of Harvard University demonstrates, the electromagnetic forces in a tiny magnet can easily overwhelm a mountain range." "It turns out that gravity is many, many orders of magnitude weaker than the other forces." "Surely gravity doesn't seem that weak when you're climbing up a mountain, but with an incredibly tiny magnet," "I can pick up this paper clip with the tiny magnet." "Is that amazing?" "Well, this tiny magnet is competing against the gravitational force of the entire Earth." "At a fundamental level, the force of gravity is much weaker than the other forces." "But the problem is, we don't understand where this huge discrepancy comes from." "And it's this discrepancy that's stopping Hawking achieving his dream." "He can't create a Theory of Everything until he can explain what happened to gravity at the moment of the Big Bang, when the universe was tiny." "If we want to know what happened when the universe began, we have to have a theory that can describe gravity on a very small scale." "Hawking has struggled for decades to solve this problem." "But now he's in a race." "The final breakthrough may well come from someone else." "Physicists love to explain how our universe arose and how it works." "We understand enormous amounts, but when asked, how did it all come to be, we don't have one single answer, yet." "In 1988, Stephen Hawking's book," "A Brief History Of Time, was published." "Few expected it to be such a runaway success." "I remember reading the draft of his book on a train journey to Beijing, and...well, to be honest, when I read the book," "I certainly did not anticipate that it was going to be the bestseller it really was." "Overnight, Hawking became a household name." "He was in great demand." "My first guest tonight's a truly remarkable man, regarded by many as a genius." "Professor Stephen Hawking." "But the pressure of fame took its toll on his marriage." "Hawking had set out to write a book that would carry his message to a wider audience, and make him a bit of cash to help pay for the expensive specialist care he needed." "But he never anticipated the upset it would cause in his personal life." "After years of caring for Hawking alone, his wife Jane suddenly found herself surrounded by nurses and assistants." "In an interview in 2000," "Hawking's youngest son Timothy recalled how, when he was nine years old, his life was turned upside down." "It changed things completely." "Lots of new people coming into the house, wandering in and out." "The front door was always open." "I think my mum found it hard, because nurses started treating our house as their own home." "You know, taking baths, helping themselves to food, and our house was turning into a hospital." "It started to unsettle the balance of the family." "Suddenly, my dad seemed to become a lot more outgoing with people outside the house." "He was starting to let his hair down in some ways." "He started buying Beatles CDs and stuff, and... you know, having parties." "In fact, he could also, of course, be more independent now that he had his nurses, and that actually made his life easier, which meant that he didn't have to be with my mum 24 hours a day." "Two years after his book's publication," "Hawking and his wife Jane were separated." "In 1995, he married his nurse, Elaine Mason." "I am marrying the woman I love." "And the world waited eagerly for his much-vaunted Theory of Everything." "When the Brief History Of Time first came out," "I think physicists were fairly hopeful that we would have this final theory of everything, maybe within just a few decades." "In 1988, there was certainly cause for optimism." "Only gravity had to be explained and brought into the fold." "Back in the 1970s," "Hawking had already given physics an inkling of how it might work." "By applying quantum mechanics to the edge of the black holes in the 1970s," "I was able to revolutionise our understanding of them." "Hawking had proved it was possible to unite the theories of the very large - stars, planets and gravity - as originally proposed in Einstein's Theory of Relativity, and blend in some of the theory of the very tiny" " of atoms, quantum mechanics." "To extend our understanding further, we need to bring quantum mechanics into the heart of the black hole." "By joining the theories of the large and the tiny in a limited way," "Hawking had utterly changed our picture of black holes." "He showed they chew up our universe, but then explode, giving off vast amounts of energy and material that eventually forms new stars." "Physicists were fascinated." "It was as if Hawking had pulled down a wall." "Suddenly, the theorists of the very large and the theorists of the very small had something to talk to each other about." "If Hawking could find a connection between the large and the tiny in black holes, there must be more." "Surely a single theory of the universe could be found that would include how gravity worked, both now, and at the universe's beginning." "The race was on." "Hawking first became enthused about an idea called super symmetry." "Super symmetry is based on the notion that before the Big Bang, when the universe was just a single point, everything including gravity was merged with perfect symmetry into one almighty super force." "We think that at the instant of creation, there was a super force, a master force, a single force that governed the properties of this dot-like universe, but then the universe began to expand and the force cracked." "When the universe began, the super force was entirely symmetrical." "It was made of the same stuff and it all behaved in the same way." "But then, as it expanded, this symmetry started to break." "In the milliseconds after the Big Bang, forces flew off in all directions, and the universe became messy and uneven." "Gravity and all the other parts of nature we see today are the irregular, imperfect descendents of the original symmetry." "The theory of super symmetry solved part of the problem Hawking had with gravity." "Now the whole of nature, including gravity, could be unified with the Big Bang by one set of equations." "But there was still a problem." "If gravity was unified with everything else at the Big Bang, why did it become so very weak afterwards, compared to the other forces?" "The brightest minds, like Hawking and Princeton professor Ed Witton, were trying to work out how the perfection of super symmetry broke and ended up as the world we see today." "Imagine sitting down at a dinner table." "There's a glass to your left, and there's a glass to your right." "So the arrangement of the table has a symmetry between left and right, at least for the glasses." "It works fine if everybody picks up the glass on the left, or if everyone picks up the glass on the right." "But a mixture, where everybody sits down and ends up with the glass, breaks the symmetry." "You all pick the glass from the left or the glass from the right." "That's an example of what physicists call spontaneous symmetry breaking." "And it's ubiquitous in the real world, both for the electrons in a piece of iron, and for the early universe settling down from the Big Bang." "Explaining why the universe had settled down the way it had was the next problem Hawking had to solve." "Super symmetry made lots of sense, but there seemed to be no particular reason why gravity should end up so weak." "Much work still needed to be done, but Hawking's ability to communicate was slowing down drastically." "Today, it is a constant effort." "I'm gonna demonstrate using a hand switch, which is what Professor Hawking used to use until about two years ago." "Now, he uses a menu system, which is basically a big screen full of words." "And when he presses the switch once, you see this highlighted section that goes up and down." "That's actually selecting which part of the screen he wants to speak from." "So if you press it and then press it again while it's over the top half, it's now worked out that he wants to say something in the top half of the screen." "And if you press it a third time on the right line, it'll go along that line, and a fourth time lets you select a letter." "And now we've got a whole screen full of words beginning with Q and R, and you can do the same thing again, and you can select a word." "That's how he builds up a sentence word by word, or if he wants to speak a word that isn't in the list, he can do it letter by letter as well." "Throughout the '90s, at only four words a minute," "Hawking worked away at the problem of gravity." "but cutting-edge physics became increasingly dependent on complex maths, and Hawking was reliant on students and colleagues to perform computations." "Thank you very much." "The next big breakthrough came not from Hawking, but from a colleague just down the corridor in Cambridge." "Professor Michael Green is one of the big hitters in what is known as super string theory, or string theory for short." "It suggests that all the particles and forces of nature are actually vibrating little string-like objects, and it seems to magically solve the problem of gravity that Hawking is struggling with." "One of the remarkable things about string theory is that it necessarily includes gravity, and in fact, in the earliest days of string theory, people were trying to formulate a theory which did not include gravity." "They didn't understand that string theory necessarily included gravity." "String theory is a radically different way of looking at our universe." "In string theory, the entire universe, including space, time and even gravity, are made up of tiny, string-like objects that only appear to us to be different particles because of the different ways they vibrate." "LUTE STRUMMING" "VIOLIN BOWING" "BASS GUITAR PLUCKING" "The theory suggests that our world is just a giant mesh of vibrating strings." "String theory brings the theories of the very large and the very small together beautifully." "Einstein's Theory of Relativity describes a universe where space bends and curls, just like pieces of string." "Quantum mechanics says particles are wavy and fuzzy, a concept well-expressed by vibrating strings." "First of all, each vibration of the string corresponds to a particle." "Therefore, string theory is a quantum theory." "The jumble of particles we see is nothing but the jumble of notes, vibrating on a string." "But when the string moves in space and time, it forces space and time to curl up, and that's why we have precisely Einstein's equations." "Because string theory can encompass both the tiny quantum world and the vast world of space, it looked like it might hold the answer to the problem of gravity that was so tormenting Hawking." "But it was not Hawking who saw the possible solution." "It was that chap down the corridor, Michael Green." "Here in Aspen, Colorado, he and his colleague John Schwarz finally cracked how to make gravity fit the theory." "We were making progress, we felt, in understanding how string theory - or super symmetrical string theories, which we called super string theory to understand how super string theory works." "But in the early '80s, there was very little interest in our work." "People were pursuing other, somewhat related, but other directions, and so we were convinced that what we were doing was quite important, and we found it rather puzzling that there wasn't more interest from our colleagues." "It sort of culminated, as I remember it, essentially in one day, when suddenly everything fell... all the jigsaw, pieces of the jigsaw puzzle came together." "And it was a really unusual feeling for both of us." "Green and Schwarz had made a huge breakthrough." "When the news came of the Green-Schwarz calculation, that was like a thunderclap, and I was pretty sure life would never be the same again, at least not professional life." "Green and Schwarz's version of string theory not only included gravity, but it had an amazing explanation for why gravity is so weak now." "The reason?" "The universe is made up of 11 dimensions." "It may sound like science fiction, but even Stephen Hawking is prepared to admit it might be right." "String theory is the only candidate for a theory of everything that has a certain symmetry that physicists believe in, but have not yet observed." "If it is not found, we will have to think again." "Hawking had spent decades leading the quest for a theory of everything." "Now, someone else had made the vital next step, a great step into a multi-dimensional universe." "During my lifetime, we have discovered many of the laws that govern the universe." "But we don't yet understand how they all fit together or why they seem to be finely adjusted to allow life." "Stephen Hawking has spent 45 years trying to create a theory of everything." "His main stumbling block has been finding a way to explain how gravity arose in the white heat of the Big Bang, and why it's so weak." "Now the elusive answer seems to have come from elsewhere." "String theory has been developed for 20 years now." "The latest version is called M-theory, and almost all physicists have huge hope for it as a theory of everything." "But to explain gravity's weakness, the theory has to be constructed in nine, ten, even 11 dimensions." "It sounds like science fiction, but string theorists believe those extra dimensions to be real." "But what does that actually mean?" "In string theory, in addition to the three space dimensions that we're familiar with, sideways, up and across, there are some extra dimensions." "In the simplest versions of the theory, we say there are six extra dimensions, which we don't see directly in the physical world." "But nevertheless they could be there." "We can't see the extra dimensions because they're outside our 3D universe." "Some could be bigger than our three dimensions." "Our entire universe could be sitting inside a higher dimension." "We could be a bit like fish in a tank, unaware of the world outside, unaware of the extra dimensions." "Today we physicists believe that we are the fish, we spend all our lives in three dimensions, going forward, backward, left, right and up and down, not realising that there could be other dimensions," "other universes, other ponds." "Perhaps as many as 11 dimensions in a multiverse of universes." "Some people say, "Well, what's at the edge of the universe?"" "Is there a wall that says," ""The end of the universe, do not pass go." "This is it folks."" "The answer is no." "Think of the way Columbus handled that question." "People said, "Columbus, if the earth is round, then what happens when you fall off the edge?"" "And then Columbus said," ""There is no edge, cos you just keep on going around in a circle."" "So in two dimensions, the earth is infinite, you can spend all your time going in a circle, but in three dimensions, the earth is a ball." "It's finite." "In the same way our universe looks infinite in three dimensions." "You can go anywhere and there's no wall out there, but in four dimensions, in hyperspace, perhaps it's just a pond." "But extra dimensions do not have to be bigger than our 3D universe." "Some could be tiny." "They could be curled up so small we don't notice them and that may explain why gravity is so very weak if Harvard professor Lisa Randall's work is correct." "It could be that at every point in space there are these curled-up extra dimensions, looking somewhat like these doughnuts do." "It's hard to imagine because the idea is that if there are two curled-up extra dimensions, curled-up into a doughnut shape, or we call it a torus, there could be one of these doughnuts at every point in space," "and it could be a higher dimensional doughnut which is hard to draw and even harder to eat, but it could be that there are even more curled-up extra dimensions in this way, and that, what this illustrates is that" "at every point in space we have one of these doughnuts." "And we may not have seen these extra dimensions because they are too small for us to measure." "Physicists now believe that the tiniest, immeasurably small points in space may actually conceal curved-up extra dimensions." "And that would affect how we perceive gravity." "The idea from string theory is that gravity is not weirdly weak after all, it's just that we don't experience it fully." "It may be as strong as all the other forces in the universe but its effects are weakened by having to make its way through extra dimensions." "It's a bit like distant music, fighting its way through a noisy environment." "BLURRED MUFFLED MUSIC" "Maybe that's why gravity is so weak because most of gravity flies into hyper space and disperses and we only see the remnants." "That's why when you hear this music it's very, very faint, cos most of the music has gone in a different direction and we only hear the remnants." "Extra dimensions act a bit like a showerhead." "Up close to the tiny extra dimensions, gravity is strong, but as you move away it gets very weak, very quickly." "The final piece in the theory of everything is potentially hovering over the last hole in the jigsaw." "The holy grail is within reach." "If string theory is correct, then gravity is as strong as all the other forces in our universe but just feels weak because it's fighting its way through extra dimensions." "The trouble is nobody, not even Hawking, has any idea whether any of this is true or not." "Super symmetry, string theory," "M-theory, extra dimensions" " they all exist... on paper." "There is a little evidence that some of the particles predicted by super symmetry exist." "As yet, there's no hard proof the rest are any more than elegant theories." "But we may be standing on the brink of a huge breakthrough." "Particle physics has made fabulous advances in the last 20 years." "By colliding particles at the kinds of energies that would have been around at the Big Bang we have unified three of the four forces." "Gravity still refuses to be tamed but, perhaps, not for long." "Hawking's optimism in his professional life is matched only by the strength he displays in his personal life." "His second marriage, to his nurse Elaine Mason, started to unravel in 2004." "For the second time in their ten-year marriage, the police started an investigation into alleged abuse." "Members of his nursing staff claimed he had been virtually abandoned outdoors to suffer sunstroke." "But claims were met with counter-claims and withdrawals." "Throughout," "Hawking steadfastly refused to criticise his second wife." "However, in late 2006, Hawking filed for divorce." "Relations with his first family now seem to have resumed on a normal, civilised basis." "Last year," "Hawking co-authored a children's book with his daughter Lucy." "The subject?" "Physics, of course." "Using physics to explain how our universe came about has been Stephen Hawking's lifelong obsession." "String theory might be the answer he seeks and, now, there's an outside chance that we're about to find evidence which will finally tell us how the universe began." "At CERN, near Geneva in Switzerland, they're building the biggest experiment ever conceived." "The Large Hadron Collider works by firing subatomic particles in opposite directions around a 16 mile tunnel." "They hit each other at nearly the speed of light." "The energies involved replicate the conditions that were around in the early universe." "In theory, the machine is not quite powerful enough to explore what gravity was like at the exact moment of the Big Bang." "Or is it?" "Trying to unify gravity with the other forces in nature would involve an experiment with incredibly high amounts of energy." "That would be far beyond the capacity of any machine we have ever built but if string theory is correct, help may be on hand from extra dimensions." "Amazingly, there is a possibility that we will see extra dimensions at CERN." "The evidence for that would be tiny exploding black holes, something Hawking himself predicted." "So you might ask the question," ""Is it possible that by colliding particles in an accelerator you could actually produce little black holes?"" "You might indeed." "And the answer is maybe." "Black holes can be any size, even as tiny as an atom." "If gravity really is seeping into our world through extra dimensions, like water out of a shower head, then incredible things might happen at CERN." "If two particles meet right next to the shower head where gravity is strongest, they might suddenly form a mini black hole." "Once you get within the distance associated with these extra dimensions, then gravity goes up more fast as distance decreases." "That's what's allowing you to form the black holes more easily." "But Hawking's work on black holes predicts that they would explode very quickly." "And if the black holes were formed in the Large Hadron Collider, they would be very noticeable." "It's been said that they would shine like a Christmas tree and you would be able, not only to detect the black holes, you would be able to detect the evaporation of the black hole as predicted by Hawking." "Such a result would be a double whammy." "For the first time ever there would be experimental evidence to back up Hawking's theories about black holes." "Hawking might even get a Nobel prize, and there would be strong evidence that extra dimensions are real, and that string theory is really on the road to a theory of everything." "You would produce extra particles, particles that can travel into the extra dimension." "And if we see those particles it would be strong evidence that extra dimensions actually exist." "The big switch on at the Large Hadron Collider is waited for with bated breath by the whole of physics." "It might well fundamentally change our view of our universe, and shed light on the big questions that Hawking has always sought answers to." "For Stephen Hawking it will be yet another reminder of our true place in the vast cosmos." "We once thought we were at the centre of the universe." "Then we thought the sun was." "Eventually we realised we were just on the edge of one of billions of galaxies." "Soon we may have to humbly accept that our 3D universe is just one of many multi-dimensional worlds." "So after a lifetime of trying to answer the big questions about existence, what does the universe look like to Stephen Hawking?" ""Can we now see where we came from and where we are going?" "I am tempted to say that science is about ever-expanding horizons, and that new discoveries only help us to frame questions in more and more accurate ways."" "However, there is more to the answer than that." "Stephen Hawking is dogged in his determination." "He has lived 45 years longer than his doctors predicted." "He may soon lose the use of his vital facial muscles and become totally paralysed." "None of it seems to phase him." "I think Stephen faces in his thoughts absolutely every scenario he could possibly face." "He's not afraid of any scenarios really." "I mean, he's an incredibly brave person and a huge risk taker." "You know, he's got a really... incredible appetite for life." "Just about the only area in his life where Hawking is a stick-in-the mud is his world-famous voice." "It's a voice that was cobbled together from a 1980s telephone answering system." "The card was actually first designed for a sort of... automated telephone use." "This was back in the 1980s when that was a really, really difficult thing to do, and it was a cutting edge synthesiser at the time." "'Can you finish in ten minutes?" "'" "He could have a voice that is more realistic, more easy to understand, and would use less power and wouldn't break so often." "But the one he has is recognised all over the world and it's the one he wants to keep." "Thank you very much." "So what does the universe look like to Stephen Hawking?" "Remarkably he's one of the few scientists who've tried to do more than compute what happened at the Big Bang, and how it evolved afterwards." "He's proposed why the Big Bang happened in the first place." "The universe is governed by two kinds of laws laws of evolution which determine how the universe develops in time given its state at one time, and boundary conditions which determine the initial state." "So far, almost all scientific effort has been devoted to finding laws of evolution." "But Jim Hartle and I proposed the "no boundary condition"" "as the only reasonable initial condition for the universe." "Hawking's "no boundary condition"" "is his most radical suggestion to date." "It's a proposal, not a theory, but it is based on strong science." "Hawking's universe did not have a beginning, but bizarrely it has also not existed for ever." "The best analogy Hawking can give is that of bubbles, but without the man to blow them up." "Hawking thinks that the universe spontaneously arises." "Time begins when the universe begins." "It goes on expanding, perhaps for ever." "In Hawking's mind, our universe has no creator." "It came out of nothing and exists all on its own." "It's the ultimate free lunch... ..although Hawking did think of making some cash out of it." "Maybe Hartle and I should have patented our idea, and have charged everyone royalties for their existence." "And interestingly, many within physics are coming round to Hawking's radical view." "Within the 11 dimensions of string theory, some scientists think our universe could be just one of many 3D blobs." "In string theory, it's possible that there may exist entirely separate giant sheets of space." "String theorists call them membranes, or "branes" for short and suggest that 3D universes can form on them." "This is where we reach the end of our understanding." "And now, even the world's greatest physicists start guessing." "It could be that matter, the stuff we know about, is actually stuck, or lives, on the surface of a brane." "And the idea that we are stuck to one of many membranes raises the distinct possibility that membranes may clash out there in the greater universe." "If we are just one brane, maybe there are many other branes." "There could be other branes elsewhere which we're unaware of." "Each of these branes would in some sense correspond to a different universe, and maybe these branes would even occasionally collide." "One of the ideas that's been proposed is that the Big Bang explosion 14 billion years ago originated as a collision of branes." "Not only is it possible to make such a theory, but it's got some attractive features, because it can explain why gravity appears to be so weak." "It's all pretty heady stuff." "It's the kind of thing physicists dream about, and it's all a long way off being proven." "But for Hawking it's the search that gives his life meaning." "During my lifetime, we have discovered many of the laws that govern the universe, but we don't yet understand how they all fit together or why they seem to be finely adjusted to allow life." "I am confident that we will resolve these mysteries, and I think the years ahead will be a golden age of discovery." "Stephen Hawking may not have single-handedly created a theory of everything, but he's come within a whisker." "He may be almost completely paralysed, but that hasn't stopped him being a tireless explorer." "Soon, this master of the universe will be off on his travels again." "Hawking plans to be on the first commercial flight out into space." "As always, there's a reason for his adventure." "I think we are acting with reckless indifference to our future on planet Earth." "At the moment, we have nowhere else to go." "But in the long run, the human race shouldn't have all its eggs in one basket or on one planet." "I just hope we can avoid dropping the basket until then." "Subtitles by Red Bee Media Ltd"