The Origin of the Universe - Prof Stephen Hawking

I'm Angelina Yee executive director for the Institute for Advanced Study at the Hong Kong University of Science and Technology it is my great honor to be your host for professor Stephen Hawking's lecture today the first in a series of stellar lectures to inaugurate the Institute the Institute for Advanced Study in Hong Kong is the brainchild of president Paul Jewell who has a dream he dreams of Hong Kong China and Ages and Renaissance into a global intellectual and innovation center bringing together the world's most brilliant minds the Institute will drive cutting-edge discovery and scholarship to meet the great challenges of the 21st century there is nothing more uplifting than to have Stephen Hawking announced the launch of a brave new voyage to imagine a different space at different time for Hong Kong before I invite professor Chu to give his welcoming remarks may I call your attention to a few mundane but important matters first of all photography is strictly prohibited throughout the lecture professor Hawking uses a blank switch to control his communication system camera flash will cause his delicate communication system to break down second professor Hawking communicates through a computer synthesizer which may take some time to convey please be patient and remain silent throughout the lecture thank you for your understanding and cooperation cocoon zone totally deterministic Hong Kong forget I hope go down in Korean hormone control hello for Comikaze go eat okay human helicopter her t-t-t-tank away laurihart on yoga see home they are cows oh hello home I see Kaiser NATO honking daddy Naga song kreygasm calm down we provide clicker cotton cotton in home controls only turn home so he hey click on door Jackie can you come see being the program counselor Congo Union hop sing hey they don't work i cotton so in their kentucky can hallelujah cans kissing getting done Chang kawaii pateen acting young lon Tata Takata along to my hotel I now invite professor chiu president of the Hong Kong University of Science and Technology and the founding director of the Institute for Advanced Study to deliver his welcoming remarks [Applause] good afternoon council chairman dr. John Chen distinguished guests ladies and gentlemen I have an impossible test today how do you introduce a living legend we're here today not because professor Hawking is the location professor of mathematics at the University of Cambridge not because professor Hawking is the recipient of a large number of prestigious awards not because professor Hawking is the originator of many groundbreaking scientific theories nor that he is the author of many best-selling books including a brief history of time we are here because he is larger than life larger than any human institution professor Hawking represents the miracle of human mind and a triumph of the human spirit he has inspired us and will continue to inspire future generations to reach for the stars for orders the local news media has corn a new term the Hawking spirit the term is here to stay and has become part of our vocabulary for the eighteen thousand 1800 audience here and hundreds of thousands of those watching live broadcast of this event and countless others professor Hawking is a symbol of the limitless mystery of the universe the endless fascination of scientific discovery and boundless imagination of human mind we at the Institute for Advanced Study are most fortunate to have professor Hawking here by delivering this inaugural lecture he has greatly encouraged us to pursuit our shared dream the dream is to spread the excitement of knowledge an Elvis scientist research and discovery in this part of the world to the highest level but it is not just the University of Science and Technology or the Institute of events study they owes him a debt of grace the gratitude all of us in Hong Kong are deeply gratified agretti grateful to him for his example for the young people in the audience today his the living proof that nothing is impossible normally the origin of universe is a subject light-years away from the minds of people of Hong Kong but today I invite all of you here and those who are watching the TV live broadcast to enjoy this lecture to savor every words and above all to absorb the presence of a great end in a unique human being and the most brilliant scientific mind ladies and gentlemen I am proud and honored to BRIT present to you professor Stephen Hawking's [Applause] [Applause] yeah can you hear me according to the pasando people of central Africa in the beginning there was only darkness water and the Great God bomba one day bomba been paid from a stomachache vomited up the Sun the Sun dried up some of the water living land still in pain bomba 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 the answer generally given was that humans were a comparatively recent origin because it must have been obvious even at early times that the human race was improving in knowledge and technology so it can't have been around that long or it will have progressive or for example according to Bishop Ussher the book of Genesis laced the creation of the world at 9:00 in the morning on October the 27th 4004 BC on the other hand the physical surroundings like mountains and rivers changed very little in a human lifetime they were therefore thought to be a constant background annealer to have existed forever as an empty landscape or to have been created at the same time as the humans not everyone however was happy with the idea that a universe had a beginning for example a riffle the most famous of the Greek philosophers believed a universe had existed forever something eternal is more perfect than something created he suggested a reason we see progress was at floods or under natural disaster had repeatedly said civilization back to the beginning the motivation for believing in an eternal universe was a desire to avoid invoking divine intervention to create a universe instead of going conversely those who believed the universe had a beginning used it as an argument for the existence of God as the first cause or a prime mover of the universe if one believed that the universe had a beginning the obvious question was what happened before the beginning what was God doing before he made the world was he preparing hell for people who asked such questions the problem of whether or not the universe had a beginning was a great concern to the German philosopher Immanuel Kant he felt there were logical contradictions for any moniece either way if the universe had a beginning why did it wait an infinite time before it began he called at a thesis on the other hand if the universe had existed forever why did a taken infinite time to reach the present stage he called that the antithesis both the thesis and the antithesis depended on cancer sumption along with almost everyone else that time was absolute that is to say that went from the infinite past to the infinite future independently of any universe that might or might not exist in this background this is still the picture in the mind of many scientists today however in 1915 Einstein introduced his revolutionary general theory of relativity in this space and time were no longer absolute no longer a fixed background to events instead they were a dynamical one that he had were raped by the matter and energy in the universe they were defined only within the universe so it made no sense to talk of a time before the universe began that would be like asking for appointed south of the South Pole it has not defined if the universe was essentially unchanging in time as was generally assumed before the 1920s there would be no reason that time should not be defined arbitrarily far back any sort all beginning of the universe would be artificial in the sense that one could extend the history back to earlier times thus it might mean that the universe was created last year but with all the memories and physical evidence to look like it was much older this race of deep philosophical questions about the meaning of existence I shall deal with these by adopting what is called the positivist approach than this the idea is that we interpret the input from our senses in terms of the model we may from the world one cannot ask whether the model represents reality only whether it works a model is a good model the first it interprets a wide range of observations in terms of a simple and elegant model and second if the model makes definite predictions that can be tested and possibly falsified by observation in terms of the positivist approach one can compare two models of the universe one in which the universe was created last year and one in which the universe existed much longer the model in which the universe existed for longer than a year can explain things like identical twins that has a common cause more than a year go on the other hand the model in which the universe was created last year cannot explain such events so the first model is better one cannot ask whether the universe really existed before a year ago or it just appeared to than the positivist approach they are the same in an unchanging universe there would be no natural starting point the situation changed radically however when Edwin Hubble began to make observations with a hundred inch telescope on Mount Wilson in the 1920s Hubble found that stars are not uniformly distributed throughout space but are gathered together in vast collections all galaxies by measuring the light from galaxies bubble to determine their velocities he was expecting that as many galaxies would be moving towards us as we're moving away this is what one will have in a universe that was Sun changing with time but Mr Price Hubble found that nearly all of the galaxies were moving away from us moreover the further galaxies were from us the faster they were moving away the universe was not unchanging with time as everyone had thought previously it was expanding the distance between distant galaxies was increasing with time the expansion of the universe was one of the most important intellectual discoveries of the 20th century or of any century the transform the debate about whether the universe had a beginning if galaxies are moving apart now they must have been closer together in the past if their speed had been constant they would all have been on top of one another about 15 billion years ago was this the beginning of the universe many scientists were still unhappy with the universe having a beginning because it seemed to imply that physics brought down one would have to invoke an outside agency which for convenience one can call God that determine how the universe began later for advanced theories in which the universe was expanding at the present time but didn't have a beginning one was a steady state theory proposed by Bondi gold and oil in 1948 in the steady state theory as galaxies moved apart the idea was that new galaxies would form from matter that was supposed to be continually being created throughout space the universe would have existed forever and would have looked the same at all times this last property had a great virtue from a positivist point of view of being a definite prediction that could be tested by observation the Cambridge radio astronomy group under Merton royal did a survey of reap radio sources in the early 1960s these were distributed fairly uniformly across the sky indicating that most of the sources lay outside our galaxy the weeper sources with me further away on average the steady state Theory predicted the shape of the graph of the number of sources against source strength but the observation showed more food sources and predicted indicating that the density sources less higher in the past this was contrary to the basic assumption of the steady state theory that everything was constant in time for this another reasons the steady state theory was abandoned another attempt to avoid the universe having a beginning was a suggestion that there was a previous contracting phase but because of rotation and local irregularities the matter would not all fall to the same point instead different parts of no matter would miss each other and the universe would expand again with the density remaining finite to Russians lifshitz and kaletnik are actually claimed to have proved that a general contraction without exact symmetry would always lead to a bounce with the density remaining finite this result was very convenient for Marxist Leninist dialectical materialism because it avoided awkward questions about the creation of the universe that therefore became an article of faith for Soviet scientists when lifted single at nakum published their claim I was a 21 year old research student looking for something to complete my PhD thesis I did believe their so-called proof and set out with Roger Penrose to develop new mathematical techniques to study the question we showed that the universe couldn't bounce the Feinstein's general theory of relativity is correct there will be a singularity a point of infinite density and space-time curvature where time has suffocating observational evidence to confirm the idea that the universe had a very dense beginning came in October 1965 a few months after my first singularity result with the discovery of a faint background of microwaves throughout space these microwaves are the same as those in your microwave oven but very much less powerful they would heave your pizza only two minus two seventy one point three degrees centigrade not much good for defrosting the pizza let alone cooking it you can actually observe these microwaves yourself set your television to an empty channel a few percent of the snow you see on the screen will be paused by this background of microwaves the only reasonable interpretation of the background is added as radiation left over from an early very hot and dense state as the universe expanded the radiation would have cooled until it is just a faint remnant we observed a day although the singularity theorems of Penrose and myself predicted that the universe had a beginning they didn't say how it had begun the equations of general relativity would break down at a singularity the sign Stein's theory cannot predict how the universe will begin but only how it will evolve once it has begun there are two attitudes one can take the results of Penrose and myself one is that blood shows of the universe began for reasons we could not understand this was a view of Pope John Paul at a conference on cosmology in the Vatican the Pope told the delegates that it was okay to study the universe after it began but they should not inquire into the beginning itself because that was the moment of creation and the work of God I was glad he didn't realize I had presented a paper at the conference suggesting how the universe began I did fancied the thought of being handed over to the Inquisition like Galileo the other interpretation of our results which has favored by most scientists that indicates that the general theory of relativity breaks down into very strong in gravitation votes in the early universe it has to be replaced by a more complete theory one would expect this anyway because general relativity does not take account of the small scale structure of matter which is governed by quantum theory this does not matter normally because the scale of the universe is enormous compared to the microscopic scales of quantum theory but when the universe is a blank size a billion trillion trillionth of a centimeter the two scales are the same and quantum theory has to be taken into account in order to understand the origin of the universe we need to combine the general theory of relativity with quantum theory the best way of doing so seems to be a use fineman's idea of a sum over histories Richard Feynman was a colorful character who played the bongo drums in a strip joint in Pasadena and was a brilliant physicist at the California Institute of Technology he proposed that a system brought from us today to estate me by every possible path or history each path or history has a certain amplitude or intensity and the probability of the system going from A to B that's given by adding up the amplitudes for each path there will be a history in which the moon is made of blue cheese but the amplitude is low which has bad news for mice the probability for a state of the universe at the present time is given by adding up the amplitudes for all the histories and with that state but how did the history start this is the origin question in another guise does it require a creator a degree of the universe began or is the initial state of the universe determined by a law of science in fact this question would arise in the histories of the universe went back to the infinite past but it is more immediate if the universe began only 15 billion years ago the problem of what happens at the beginning of time there's a bit like no question of what happened at the edge of the world when people thought the world was flat there's the world of flat plate with the sea pouring over the edge I have tested this experimental e I have been around the world and I have not fallen off as we all know the problem of what happens at the edge of the world was solved when people realized that the world was not a flat plate but a curved surface time however seemed to me different it appeared to be separate from space and to be like a model railway track if it had a beginning there would have to be someone to set the trains going iron Stein's general theory of relativity unified time and space a space time but time was still different from space and was like a corridor which either had a beginning an end or went on forever however when one combines general relativity with quantum theory Jim Hartle and I realized that time can behave like another direction in space under extreme conditions this means one can get rid of the problem of time having a beginning in a similar way in which we've got rid of the edge of the world suppose the beginning of the universe who was like the South Pole of the earth with degrees of latitude playing the role of time the universe would start as a point at the South Pole as one moves north the circles are constant latitude representing the science of the universe will expand to ask what happened before the beginning of the universe who would become a meaningless question because there is nothing south of the South Pole time as measured in degrees of latitude would have a beginning at the South Pole but the South Pole is much like any other point at least so I have been told I have been to Antarctica but not the South Pole the same laws of nature hold at the South Pole as in other places this would remove the age-old objections of the universe having a beginning that it would be a place where the normal laws brought down the beginning of the universe would be governed by the laws of science the pictured limb hurdle and I developed of the spontaneous quantum creation of the universe would be a bit like the formation of bubbles of steam and boiling water the idea is that the most probable histories of the universe would be like the surfaces of the bubbles many small bubbles will appear and then disappear again this would correspond to many universes that would expand but will collapse again while still of microscopic size they are possible alternative universes but they are not of much interest since they do not last long enough to develop galaxies and stars let alone intelligent life a few of the little bubbles however will grow to a certain size at which they are safe from rip collapse they will continue to expand at an ever-increasing rate and will form the bubbles we see they will correspond the universe in that would start off expanding at an ever-increasing rate this is called inflation like the way prices go up every year the world record for inflation was in Germany after the first world war prices rose by a factor of 10 million in a period of 18 months but that was nothing compared to inflation in the early universe the universe expanded by a factor of million trillion trillion in a tiny fraction of a second unlike inflation and prices inflation in the early universe was a very broad thing that produced a very large a uniform universe just as we observe however it would not be completely uniform in the sum over history's history that are very slightly irregular we'll have almost as high probabilities as a completely uniform and regular history the theory therefore predicts that the early universe is likely to be slightly non-uniform this irregular release would produce small variations in the intensity of the microwave background from different directions the microwave background has been observed by the Maps satellite and was found to have exactly the kinds of variations protected so we know we are on the right lines the irregularities in the early universe will mean that some regions will have slightly higher density than others the gravitational attraction of the extra density will slow the expansion of the region and can eventually cause a region to collapse to form galaxies and stars so look well at the map of the microwave sky there is a blueprint for all the structure in the universe we are the product of quantum fluctuations in the very early universe God really does play dice we have made tremendous progress in cosmology in the last hundred years the general theory of relativity and the discovery of the expansion of the universe shattered the old picture of never existing an everlasting universe instead general relativity predicted that the universe and time itself would begin in the Big Bang it also predicted that time will come to an end in black holes the discovery of the Cosmic Microwave Background and observations of black holes support these conclusions this is a profound change in our picture of the universe and of reality itself although the general theory of relativity predicted that the universe must have come from a period of high curvature in the past that could not predict how the universe would emerge from the Big Bang lost general relativity on its own cannot answer the central question in cosmology why is the universe the way it is however if general relativity is combined with quantum theory that may be possible to predict how the universe would start it would initially expand at an ever-increasing rate during the so-called inflationary period the merit of the two theories predicted that small fluctuations will develop and lead to the formation of galaxies stars and all the other structure in the universe this is confirmed by observations of small non-uniformities than the Cosmic Microwave Background with exactly the protected properties so it seems we are on our way to understanding the origin of the universe so much more work will be needed a new window on the very early universe will be open when we can detect gravitational waves by accurately measuring the distances between spacecraft gravitational waves propagate freely to us from earliest times unimpeded by any intervening material by a contrast lighter scattered many times by free electrons the scattering goes on until the electrons freeze out when the universe has 300,000 years old despite having had some great successes not everything is solved we do not yet have a good theoretical understanding of the observations that the expansion of the universe is accelerating again after a long period of slowing down without such an understanding we cannot be sure of the future of the universe will it continue to expand forever as inflation a law of nature or will the universe eventually collapse again new observational results and theoretical advances are coming in rapidly cosmology is a very exciting and active subject we are getting close to answering the age-old questions why are we here where did we come from thank you for listening to me I'm still awestruck may I now invite esteemed Council Chairman dr. John Chiang to give a vote of thanks to professor Stephen Hawking professor Hawking millions of copies of your book a brief history of time have been sold worldwide since news of your visits leaked months ago the book has been selling like hotcakes in Hong Kong no doubt all the bookstore owners would want me to say a big thank you to you for coming to our city but you are not only good for the book business you are good for our intellects perhaps even our souls there is no substitute for seeing a great thinker in the flesh and having his magnificent ideas explained in person thousands signed up on the website for receipts by lottery Hong Kong has bi-weekly lotteries but we have never had a lottery for a lecture all of us in this hole and hundreds of thousands more watching life broadcast on television are the lucky winners professor Hawking the impact of your visits will be felt for a long time to come you and what you stand for have become our obsession we never knew that the realm of scientific ideas can be so captivating I can find no words for our gratitude to you for making the long journey from Cambridge University to Hong Kong UST but we do have a small token to express our appreciation it is an on-the-spot sketch of the greatest living scientist by one of Hong Kong's most celebrated sketch artists mr. circle Lowe normally surco is better known for sketching horses at the races but today he has a brightest talents to sketching a great scientific mind one that gallops across the limitless universe from galaxy to galaxy professor Hawking I have the great honor to present to you on behalf of your Hong Kong UST and through your charming daughter miss Liu Lucy Hawking a special artist's rendering of your presence at this historic and never-to-be-forgotten occasion Lucy please Thank You mr. Chen we had asked professor Hawking if he'd be kind enough to take some questions from the public and the questions submitted by the public have been overwhelming we actually asked professor Hawking if he could kindly answer three questions but he's been very enthusiastic and decided to select six questions it takes an incredibly amount of time for professor Hawking to write his answers and that was why he was slightly late today I will read out the questions and professor Hawking will respond to the questions these are the six questions that he has selected I reread them out in turn are you ready Stephen the first question is from mr. Cheng Alan could gravity distorts light gravity does indeed distort light it was one of the predictions made by Einstein in 1915 when he proposed the general theory of relativity the gravity of the Sun curves the space near it and deflects light passing through it this was verified by observations during the Eclipse of 1919 light from a distant star passing near the Sun who was bent through a small angle causing a slight shift in the apparent position of the star relative to other stars thank you the second question was raised by a group of physically challenged how do you face up to such a major physical challenge and still maintain a positive worldview physically challenged there is a lot one can achieve as I have shown you can't afford to be disabled and spirit as well as physically people won't have time for you yes thank you very much the third question we have many constants in this universe for example speed of light boiling point of water gravity where do these constants come from why are they here what will happen if the values of these constants are changed the constants of nature are determined by the parameters of the standard model according to m-theory ii by the geometry of the six dimensions of space that are curled up small there is a whole landscape of possible values for these parameters but most of them give universes that are not suitable for the development of life only a few universes will intelligent life appear the last way the constants of nature has the values they do yes thank you the fourth question is there a role for God in this universe the French scientist la place explained to Napoleon's will determine the evolution of the universe but where does God fit into this picture ask Napoleon I have not needed that emphasis who was a reply thank you question number five is the universe-- a black-hole at first sight the Big Bang looks rather like the time reverse of the collapse to a black hole however there is an important difference in the Big Bang the universe starts out smooth and uniform with only tiny fluctuations on the other hand the collapse to a black hole will be highly irregular non-uniform this difference can be explained by the no boundary proposal the history of the universe and imaginary time will be a closed almost smooth surface however there will be small fluctuations because of the uncertainty principle on continuing back to real time these fluctuations grow with time they are small in the early universe and lerton gravitational collapse the early universe is not the time reverse of black hole formation thank you question six why do you have an American accent I use this a very old hardware speech synthesizer made in 1986 I keep it because I have not heard a voice I like better and because by now I have identified with it but the hardware is large and fragile anews his components that are no longer made thus I have been trying to get a software version but that seems very difficult one version had a French accent I said if I used it my wife would divorce me following on that I can't resist sharing a question of mine with you which I asked Stephen Hawking during a dinner and I'll read it out to you I asked Stephen do you have any unfulfilled ambition you'd like to accomplish during our lifetime do you want to know the answer he said I have lots of ambitions I want to know what happens inside black holes how the universe began and more immediately how the human race can survive the next hundred years and then he said I would also like to understand women a round of applause for a great scientist a great man mr. universe Stephen Hawking [Applause] [Applause] thank you for being such a wonderful audience may I ask you to remain seated while I'll invite professor Porter dr. John Chiang and Lucy Hawking to come up for a group photo please may I ask that the audience remain seated until I give the signal for you to leave the room now the audience may leave in an orderly manner please thank you very much for your support I'm very much appreciated don't attack you

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Id: c7MO3up5bZs

Length: 67min 25sec (4045 seconds)

Published: Thu Mar 15 2018