Prof. Sir Roger Penrose - Hawking Points in Cosmic Microwave Background Radiation, Quantum Spacetime

ladies and gentlemen distinguished guests it is my honor and great pleasure to welcome to community University in Bratislava the participants and guests of the quantum space-time 19 conference it is to any universities credit to organize important scientific events especially if leading scientists from all over the world agreed to participate for this reason I'd like to begin my short speech by Warren with thanking the organizers for their hard work and preparation and by thanking all of the guests for the active participants in the conference this also a pleasure for me to welcome everyone who has come to this public lecture today I have the special honor of welcoming among us an important scientist mathematician physicist and philosopher whose ideas refutation and impact epitomize a unique and under this animal brand of virtue and excellence Sir Roger Penrose sir Penrose is undoubtedly one of the thinkers who have influenced our understanding of mathematical physics the general theory of relativity and the cosmology of the universe more than will likely capable of appreciating today he still theoretical physical ideas are based on a singular expertise of mathematics which has influenced many of his students as well as theoretical physicists such as Stephen Hawking and mathematicians around the world including the recently recently deceased Michael attea remarkably the inquisitive and probing spirit of our guests hasn't been limited to investigating the physical macro world and his entities but has also focused on the micro world and especially and attempt to reconcile physical physics with an explanation of the consciousness an extraordinary trade of Sir Roger Penrose scientific research is that with the help of his imagination he often finds solutions where others believe none exists or that they are logically and mathematically impossible examples includes not only the Penrose triangle which he popularized and which inspired Morris Asher but especially the whole of his research in the field of non-periodic tilings to conclude from the position of Director of the oldest and most important University in Slovakia I would like to express my delight and support for the exceptional theoretical and experimental research ongoing at our university the much rewarding international scientific cooperation and the development of specialized theoretical physical as well as inter and multidisciplinary research spanning all fields I believe that this event will lead to further study future cooperation and will serve to inspire all areas of research therefore the Penrose allow me please once again to thank you for accepting our invitation to come to Bratislava and for giving us the opportunity to share in your ideas time and knowledge I wish the audience and inspiring and enriching experience throughout as a token of our recognition gratefulness and respect I would like to present you with this commemorative medal of Comenius University grounded upon the 100th anniversary of the university's Foundation it is truly symbolic that you become the very first of this award is not in only in the world number one but also in the physical reality which grows out of it Sir Roger Penrose our space time and attention are yours [Applause] Thank You mr. director and now I would like to ask professor Szabo with chairman of quantum space project cost to open scientific program of this public lecture hands ok good evening everybody um it's truly my honor to have been asked to make this introduction to Sir Roger Penrose sir Roger is the emeritus raus ball professor of mathematics at the University of Oxford and emeritus fellow of Wadham College in Oxford he's a mathematician a physicist a philosopher of science and as a mathematical physicist he has made unraveling contributions to general relativity and cosmology he was born in England and received this PhD from Cambridge in 1958 PhD in mathematics under the supervision of the well-known algebra and geometry John Todd shortly after his interests from pure mathematics switched over to astrophysics and since then he has played a major role of our understanding of various phenomena in general relativity he is truly revolutionized the mathematical tools that we use to study the properties of space-time so one one major indicator of esteem as a mathematician or a physicist or as any scientist is when things are named after you when you have a so people might like to name things after themselves that usually doesn't work but when your colleagues name a development after you that's a big measure of esteem it's a measure of respect and acknowledgement I have a list here of things that are either directly associated by name to Sir Roger or that are named after and there are too many of them to go through but I'll just through a few of them that you might have heard of there's the more penrose pseudoinverse that came out when he was a student there's the famous pan Rose Hawking singularity theorems cosmic censorship the veil curvature hypothesis the Newman Penrose formalism of course the famous twister theory that he invented the Penrose inequalities the Penrose interpretation of quantum mechanics the Schrodinger Newton equations the notion of spin networks which is still used today in modern approaches to loop quantum gravity he popularized the use of these things in generality called causal diagrams and today they're known as Penrose diagrams and the list goes on there's the Andromeda paradox conformal cyclic cosmology and so on and he wrote he's written popular books semi popular as I've learned he likes to call some of them and there's a book he wrote called the the road to reality a complete guide to the laws of the universe which was a big thick book summarizing his perspective on the laws of nature sir roger has also been a philosopher of science he's been interested in the connections between fundamental physics and human or animal consciousness again there's several popular books that he's published on this the famous one the emperor's new mind shadows of the mind the large the small and the human mind another measure of the steam of a scientist are awards and honors and again here there's a very long list of awards and then a collations that go to Sir Roger so I've picked out a few I hope I'm not missing any of his real favorite ones because I didn't want to list them all but he won the Adams Prize in 1966 the Hyneman prize 1971 in 1972 he was elected as a fellow of the Royal Society 1985 he received the Royal Society royal medal in 1988 he was awarded the prestigious Wolff foundation prize jointly with Stephen Hawking for their work on the Penrose Hawking singularity theorems 1989 he was awarded the Dirac medal in prize in 1990 he was awarded the Albert Einstein medal 1991 the Naylor prize of the London mathematical Society he served as president of the International Society on general relativity and gravitation from 1992 to 95 and 1994 he was knighted for his services to science and 2000 he was appointed to the order of merit 2004 he won the the Morgan medal for the London mathematical Society and in 2012 he was awarded the Richard R Ernst medal from ETH Zurich for his contributions to science and for strengthening the connection between science and society another thing that Sir Roger is famous for is he's a very gifted speaker on all levels both giving a talk at a conference such as the one we heard earlier this week for scientists and also for his public lectures I first heard Sir Roger speak back in 1997 I was on my first postdoctoral position in Oxford and this wasn't it wasn't a public lecture it was a colloquium so and the rooms were full actually didn't get to see him talk because it was so popular they had to use two rooms and the second room just had a projector showing him so I was in the room where you didn't see the real person at that time I was in the theoretical physics department at Oxford Sir Roger was in the math Medical Institute so we didn't have much encounter on with each other but um I still feel you know somewhat somewhat close to Sir Roger because um three years later in 2000 I moved to my permanent position at heriot-watt University in Edinburgh and became a colleague of Rogers brother Oliver Penrose who had been there long before me so for the past 18 years I've been a colleague of Oliver Penrose he's also a mathematical physicist but who's more famous for his work in statistical physics so on that note I'd like to welcome you all and I would like to introduce the talk by the man the legend Sir Roger Penrose [Applause] [Applause] well thank you very much for that introduction I also for that medal I wasn't expecting that and it's a great pleasure for me to to be back in Slovakia I say back I was here I don't know here exactly but I was what used to be Czechoslovakia but it's the part which is the back here so I guess that's okay in 1962 when I was at a conference in Warsaw and drove back through the country so anyway pleasure to be back and see who made now I want to say something about cosmology I apologize for using these ancient technology that I have to know where I am exactly so let me know we're talking about something which I referred to as Hawking points now to explain what they are I shall begin by talking about universe and the universe here's a picture of it well it's a cartoon I suppose this in this picture time is going up the picture and space goes this way of course I can't draw all four dimensions so you have to imagine that the one dimension of space this way is really three dimensions but that's all right you can get use of that idea I hope you can hear me adequately okay I hope that was it doesn't work that's this one well this is a picture of the universe and this is time going this way and you must think of sections through this this big space I can only of course draw one dimension of space but you have to imagine there are really three going this way you might ask for all the frilly stuff that's the back of doing well that is we don't really know where the universe closes up or whether it keeps on going most cosmologists think it keeps on going maybe it does maybe it doesn't that doesn't play an important role of what I want to say so I just you can imagine either way so the universe stars expands out and it's now doing this accelerating expansion which people call due to dark energy I don't like the term dark energy because technically it's neither dark it's invisible no is it actually energy behaves in a different way for an ordinary energy it is consistent with this term that Einstein introduced in 1917 he introduced the general theory in 1915 and a couple of years later he introduced the thing called the cosmological constant and the letter lambda and the capital data lambda is often used to describe this constant Einstein introduced it unfortunately for the wrong reason because he wanted the universal static has expanded and it was quite them became pretty clear after the observations of Edwin Hubble showed that the universe is pretty conditioning expanding and so then on Stein retracted his model he also knew attractive lambda and said that was his biggest blunder my quoting they're saying that this was his largest blunder but in fact turns out that even his plan does it truly is particular bloodlessly actually a feature of the universe now some of them who are experts in cosmology will tell me there's something missing in my picture if there's supposed to be this thing which took place right at the beginning called inflation now you see maybe I have depicted this in my picture because inflation would be right inside that little black spot and you would not know if it was there or not it's supposed to be an expansion I should explain that that there are two reasons that's not a location what is that it may be using the picture let them enter the spot the other is that I don't really believe it now that's a bit prettier ethically to say because inflation is part of current cosmology is a very foundational part and in order to get some idea of what this looks like you need a very powerful magnifying glass this I should explain that's the handle of the magnifying glass not some feature of cosmology what we have is an expansion which looks pretty well like what we see now but on a completely different scale this is a very right-wing giving in a tiny little event expanding by an enormous amount and now he seems to see an expansion it's called the exponential expansion which means it's self-similar register says how big it is at any moment the expansion rate goes with with the size of the universe so it's an exponential expansion okay now if you don't believe inflation then you had to have some another explanation for certain observational facts one of them most popularly described is that somehow this inflation answer universality it's a pretty uniform over the whole or direction of uniforms altogether a pretty uniform and this is a bit of a puzzle we'll come back to that later on but one of the explanations is that this inflation which took place here sort of any irregularities were to get ironed out by this inflation I've never really believed that argument and let me try and explain why let's suppose that the universe was contracting instead of expended and the equations of Einstein and the equations of what's called the inflict on filled with thrives of inflation in the theory are completely reversible in time so if that's a solution so these things are now let's imagine that the universe was contracting and they did have various irregularities these are the irregularities would tend to build up and build up form black holes and things that get tangled with each other and make a great mess and you won't have one horrendous mess at the end that's the likely thing that would happen now if that's a likely thing would happen why didn't this happen I should explain that you can put me in photon field which is supposed to drive equations just as well in this picture it makes no difference in the picture so that is a really much more likely thing than this and in fact you can give a measure to the improbability of this is what we seem to see as opposed to this inflation animation just to give you a feeling for that figure the improbability of this you have to think of as one in ten to the power I'd like to say how many digits is going to be how many digits is that ten to the power of 124 used to say hundred 2324 it's just it doesn't make any difference the argument absolutely no much difference to its bigger but doesn't make any difference the argument so why did I universe stuff like that and not like some horrendous mess like that well I'll come back to that that's important what I want to say but in order to talk about this I want to do a couple of mathematical tricks to the universal one of them is to squash down infinity now to give you a feeling for what there is I have a picture here the notch artist MC Escher they use many wonderful pictures very very accurately as mathematical pictures this is a picture describing what's called hyperbolic geometry it's a particular kind of geometry not quite likely Euclidean geometry we're used to but it's fairly similar and you have to imagine that these fish creatures even though they look as though they're getting smaller and smaller to get to the edge to them they're just the same silence so they squash down in this representation in a way which is what's called a conformal representation let's say squash me in one direction and any other direction is by the same amount so a middle shapes when they get squashed down remain the same shape and you can see that particularly with the eyes and the fish no matter how close to the edge they are they're still circles so the squash is just as much one there's the other this is what's called a conformal man and the advantage of the conformal map is that you can represent the infinity of the world that these fish inhabit and that infinity is represented by the circular boundaries in this picture it's just a convenient way of representing the entire hyperbolic plane you know in a finite way and this little trick is the same as I I'm using the trick into space-time geometry rather than just a special geometry and I'll come through that slides work yes that says now there's an opposite trick you can do and that is stretch out the Big Bang so and it's again when it is conformal management in the other direction this is all squash down something small and you stretch it out now all they standard cosmological models that people use in general cosmology you can do this trick too so those two tricks there's nothing unconventional about them it's it's perfectly reasonable thing to do and it's useful to to do these mathematical transformations if you want to talk about in things in the remote future if you want to talk about things going on the Big Bang it's a very handy thing to be able to do these tricks nothing unconventional now what I'm just about to tell you is unconventional that is to say that the universe we think is the whole universe that is to say the Big Bang right out to be very remote future inflation if you like and this is not in my view in the view I'm trying to express here it is not the entire universe this is one year I'm using the word yawn I looked up in the dictionary to find out how long a neon was fortunately there is no definite make the time so I thought it was all right to use the word yawn AEO in the way I spell it anyway and that is what I call this entire history of this thing which we used to think of must have a sibling that I think is the entire history of the universe squash down like this and stretched out like this and I McMahon then is the continuation of the remote future of a previous year ah remote future will be the continuation were continuing to the Big Bang of a subsequent meal and the thing is in order to make this picture return I have on the right hand side to make that picture make physical sense you have to understand that the physics at both ends can be reasonably thought of as conformally invariant physics that is to say physics where it doesn't matter whether it's big or small that the universe in some sense loses track of how big it is that's a difficult thing to swallow and I know most cosmologists have a lot of trouble swallowing it but I want to explain certain things which I think are hard to explain in any other way than the picture I described here these are pretty new just last year things I want to talk about today so it's taking people a while I think to come round where they will eventually or one thing that should be done of course is another question so let me try and explain on the physical terms what the conformal mappings do you see this is spaceship but when you've got space and time together then what we have to think are the best things we think in terms of these things called light counts that was the light you see the space-time is four-dimensional time is one of the space of the other three I'm in my pictures I'll either throw one space to mention or two away just to be able to draw the pictures now what are the light cones on now cones technically here's a picture of one that is the point in space-time there's an event that means it has no spatial dimension and no temporal dimensions was just a bit like that and this event then what is the cone well then his represents what light would do so the history of a light flash from then outwards would be described by this cone so you have to mention as time progresses we take sections up and up and up and up of course I've heard they mentioned a way but never mind so that looks like a circular section is really a sphere as time progresses oh yes thank you yes can I draw that I can draw on this thing it's not that this is that this is a class though I don't want to go under let me draw I didn't it's backwards is probably what you're telling me I have to apologize I can't see where that written my eyesight is deteriorating so I appreciate when you yell at me that there is something wrong it's probably I've got the slides upside down thank you very much okay now this is a light and it's the most important part of the description of space-time as the Curris they tell you that's really there is a pleasure like they're just subject if there was the flash originating there then it would describe this thing called a black hole or locally what we call them now now there's a couple of things I would say about this first of all what light that's the history of a photon say possibly light would be go along yes and now think about this picture here I should explain that the structure of space-time is described by what's called the metric or the metric tensor and the metric tensor is a thing which in each point in space-time requires ten numbers to tell you exactly what's going on there those ten numbers nine of them roughly speaking tell you where the light earnings or exactly how it's structured in relation to space time when I say nine is really the ratios of these tender the nine independent ratios of what's the remaining number tell you it tells you how Cox behaves so here we have a picture of a couple of clocks slipping by very close to each other at this point and the ticks of these clocks are represented by these surfaces here now the point about clocks is people often used to describe relativity theory by imagining our little rulers over the place and measuring distances rulers are now no good they're lousy at measuring distances they're not the way you measure distances anymore the meter rule in Paris well nobody would physicists would ever go and use that to measure actual distance what they would do is have a notion of a clock and then use how long it would take light to go that distance so you convert distances into times using the speed of light now the thing about times but they are now devices which are so extraordinary precise that's well I think if you don't remember the figure now but if you read right the Big Bang and it was couldn't keep time in the way box we have it now then we would know the time but it's a rather bad description because you never know exactly when the Big Bang was about appreciate but to some tiny fraction of a second precision in the clock is that great another way of putting it quarks are affected by the gravitational field and according to Einstein I can't run slower slower down here that does up there and the difference between those rates can be measured even about that distance so from here to here the difference from the race of clocks go can be actually measured if extraordinary power precise they are and the precision really ultimately comes down to two of the the two I should say most fundamental formulating of 20th century physics or the two most familiar ones of tonight one of them of course is Einsteins equals MC squared which I've written down here which tells you more or less of energy and mass are equivalent if you've got the C squared but that's just a constant so energy and mass equivalent the other one is Max Planck's formula which came a bit earlier e equals H nu I don't know whether you like to use a newer therefore something that stands for frequency so tells you that energy and frequency H again is a constant so it's telling of an energy and frequency recruitment they put the two formulas together and jam a circle frequency improvement that tells you that mass and frequency are equivalent so if you have a stable particle of a given mass it is a clock it's a clock of extraordinary precision because of those very basic rules you can't listen use that precision directly so you've got you've got to turn it down and use lots of particles and all that sort of thing all sorts of details things to make an actual clock but the reason that it's so precise is because we are using those two very fundamental laws to measure the rate of time and so time can be measured that precisely okay so we have now the ten components of the metric 911 give you the code and the tenth one gives the crowding of these services which tell you the races how they would take first thing second thing third take and so on and this is then coming in from the back first and so on so that's the picture you have light cone is more fundamental if you have mass around you see in other word the other end of the story it's not just that mass gives you clocks but if you don't have mass you don't have clocks this is the key point now let's imagine we have a photon now that's a possible of life it's 6:00 along along the curve it never even reaches the first of these services to to a photon there is no time whatsoever from its origin to where it ever gets there's no experience of time by Photon so that's and here I have a picture now here we have light cones making so this way in that way we have a light ray following the light cones that's fine that's a photon material particles they're not allowed to most of us according to theory and so therefore the world line of a material particle that's the track of that particle through space-time is always within the curves like this now you can have funny things like black holes here we have a collapse of some material produce what is a black hole and you see that the cones are all still together so the signals can't get out from here outside but something I get the business thing called the singularity in the middle which is bad news that you got close to it but you can see the cones point it was more and more and guys whatever falls in towards the central region here so you have a picture of a black hole and you have the basic feature of space-time namely this light cone structure actually if you have massive things around to so the connection measure a clock stick then you need anymore so these are these I put the little bone shape services services this way to represent them the crowding of them tells you the rate at which clocks go so this is the picture that you really need for Einstein's theory this is what you need for the conformal theory I see if you didn't have any mass this picture would be good enough if you have mass around than they determine clocks so I want you to get the feeling or the difference between these two situations because it's important for what I'm trying to say let me go back to my which I've squashed down infinity and I've stretched out the big better now you see what's going to be around in the very remote future well almost entirely photons the particles will be almost entirely photons and photos aren't interested in the scape so as far as a photon is concerned this boundary is as good as anywhere else and the other thing to bear in mind is that there's a lot of matter running around but where it's liable to end up you see we in our galaxy in the center of our galaxy isn't blackhole observations very clear on this a black hole which is about 4 million times of the mass of the Sun so 4 million Suns compresses into this tiny region and you can see it it's very impressive to see this almost in real time not quite real time you can see stars going around this object you can't see the black hole but you can see the orbits of the stars and they follow this Kepler orbits you know you have to take photographs I don't know weeks apart or something means you can actually track track they actually motion the actual motion so we know there's a four million solar mass black hole center of our galaxy now what would happen to that black hole eventually well it grows and grows as the smallest things clusters of galaxies we're in a rather small class and we have them drawn with a cluster and the triangular Lord of the elements cold and pretty small but they're much much bigger clusters out there and clusters as the universe expands they tend to hang together and so the black holes will sit there for a while and then really not again they'll run into each other you see the Andromeda galaxy is one of the killer is another member of the cluster that are galaxies in the Milky Way galaxy and we are on a collision course with the Andromeda galaxy well it's not a dangerous thing in it is probably not dangerous but it won't be for a few thousand million years so don't worry about it but this black hole is somehow to forget the figure of 40 times bigger than our one so it's a lot bigger than ours when the galaxies colliding black holes will and I don't miss each other but they will eventually feel each other out and spiral round into each other and then there will be some great explosion of a kind which I'll say something about later on gravitational waves were carrying the energy a considerable proportion at the end in that collision get carried away but nevertheless in a cluster it will end up with one big black hole a lot bigger than the Andromeda well probably they're a lot bigger once leave now the places when I say see you know direct to see them did you see the effects black holes and these black holes there are some a lot bigger than the one in you know drop the galaxy so you'll get actually huge ones and I don't know what the figure about this is but I would guess that the majority of the actual material in the cluster of galaxies will eventually get swallowed by this ultimate black hole so bear that in mind because that has a lot to say but then when you see what this picture is illustrating something else this was Stephen Hawking's greatest contribution which to realize that although black holes swallow things in this smaller radiation and so on they actually have a temperature they're not exactly cold now you might ask how are they where the smallest ones are the hottest ones and the smallest ones were there probably a few times the mass Sun and those ones well just to give you a rough idea how hot are they where you have to think of something like the coldest temperature ever made on the earth I'm not sure that's quite right with something like that and you get some idea of how hot they are not hops in other words very very cold the bigger ones are even colder but as the universe expands and expands and expands the universe in the universe will eventually get smaller by this exponential expansion smaller than even the biggest of the black holes and then the black holes things around now I remember the argument this crazy scheme which I just describing to you here came about because I was worrying about something why should I worry about universe but I was worrying about the universe thinking about the incredible tedium of the whole thing you see what's the most exciting thing that will be around in the very very low future well black holes and what happens then well the biggest ones will take something like Google the units that's ten to 100 years one with a hundred zeros years that sort of make that more long probably longer that length of time they would take before they evaporate completely away and disappear with a pop I'm calling it a pop run from the bank because even though there's a fair amount very not just before the end these explosions from the Astrophysical point of view are pretty trivial and you have this huge black hole sitting around you wait your Google years ten thousand years or something and eventually now what could be more boring than sitting around waiting for a black hole to go off-topic what's more boring is what happens after that when there are many black holes left and I began to think it's pretty depressing for to the future this wonderful universe of ours is internal eternal at tedium and I began to think well who's going to be around to be bored will run us but at least the main things about me around will be photons probably not actually having experiences that's not the point but you see the photons that salon the like home and it doesn't have any experience generalized way of saying experience any experience of the passage of time so right from can imagine in this picture you get zips along and goes right through its the boundary as far as concern is a finite tunnel so this is what they sort of picture is happened here was this picture yeah I'm worrying about well maybe it's not so boring because the photons and things will have somewhere to go this picture they find themselves into the next beyond so okay that's an emotional argument and I grant you it's an emotional argument but it has something important to say about the universe which I'll come to shortly I should say first of all there are mathematical theorems is it theorem do to make sure I get the right very upper 1/3 you to help us read written who showed under very very general circumstances that yes under very general circumstances this smooth future boundary will be better so you don't have to worry about crinkles and things like that there will be nicely smooth with a nice place to go here it's completely different from the beginning picture because I showed you this situation it's much more likely to be that rather than something which stretches out to make a nice smooth original boundary like this now why is this important well it's important because of one of the most fundamental laws of physics which is a thing called the second law of thermodynamics now what is the second law of thermodynamics say well there's a thing called entropy which is is a measure of a randomness of the situation one can be technically more accurate than that the thing of it is that the randomness of a state is measured by entropy and the entropy increases with time that may be a depressing thought but it's reasonable physically that it gets more and more round as time goes on well that's you know disbelieve because there's a lot of evidence for you but let me say in this different way rather than thinking about going into the future let's think about it going into the past now the same statements the second law is saying that as you go back into the past the entropy goes down and down of them because down have done done until well what do you find what is the best evidence we have of the existence of the Big Bang which this thing called the microwave background which was that's just a bit over 50 years ago was discovered sort of accidentally but it's radiation coming in from all directions and there are certain features of this radiation which I found by the Coby satellite the main one being following I think curve what is that curve what this curve this curve is a measurement of the intensity for different frequencies the radiation is electromagnetic magnetic like lights and radio waves and x-ray is that kind of thing and it's what's called microwave radiation and this is the four different frequencies you see different intensities and what you see is this curve here now what's the importance of that curve it's a very very precise it's precisely seeing curve I should say that there's a theoretical curve that's the black line and the observational curve well these are era bubbles you see that means that's the impossible error in the observations and you see they're quite big here but they're not really big because they're these lines are exaggerated by a factor of 500 so you could imagine the real error is 1 5 hundredths even whether the worse than here they're still hugging that pink line so the observations hug this theoretical curve to within the thickness of the incline much more much less than that so what does that tell us well this is the famous plank curve which started off quantum mechanics Max Planck beginning of the 20th century and you see this very precise curve and what it's telling you is maximum entropy now you see I regard that as what I sometimes referred to as the mammoth in the room because you're going back and back in time the entropy supposed to go down and down them down and what you see that this early stage is apparently maximum entropy you go down and down and down until you reach a maximum you don't have to be a mathematician to think there's something fishy about that well some people might say well it's something funny about the universe expanded and maybe that says no it's not and [Music] cosmologists nervous Tolman advanced I'm perfectly well understood these things no that's not the explanation but what is the explanation but what we're seeing here is matter and radiation this maximum actually said but it doesn't tell you that everything is it a maximum state the important thing it does not tell you is gravity now let me give you a picture here where I'll explain what I mean here we have this is the sort of picture that people talk about entropy often give you there we have a gas in the box and you imagine that the gas starts off by being there's a partition here and then you release the gas and as the time progresses it spreads all over the box so you have a picture of entropy increasing as the gas gets more and more uniformly distributed and this is consistent also with the microwave background because not only do you see maximum entropy yeah but you also see very great uniformity of the postcards if you can if you take in account of taken into account the fact that the earth is moving through this radiation it so slightly apart up in the direction which is going a slightly colder in the direction atom in which web is really bit direction they're going slightly hotter than the other directions like coal that you're correct for that and when you correct for that you find that the temperature variations over the whole sky are something like one part in a hundred thousand so it's pretty uniform over the whole scarlet so you're seeing something which looks like this still but when you think about gravity now you see here I've got a picture you must imagine this this is of a galactic scale boxing is the Stars running around in that box and with gravity acting on the Stars this does tend to tend to clump you see so or could be stars like will be gas or something like that and the tendency for gravity is to clump it and what you have is entropy increasing in both these pictures but what we seem to be seeing is uniformity now as far as climate is concerned that is low interview so I put my pen here and you see that these two pictures are consistent with what we see as far as matter and radio yes it's very high entropy but this is completely compensated by the fact that with gravity's consent what it tells us that the entropy is extremely low and in fact in this picture I've got enter me greasing increasing until you have a black hole and the black hole represents an absolutely enormous entropy so in fact on the universe that we know today as far as we can see out the maximum entropy in the universe is in black holes by far by an enormous factor the entropy in black holes even now is far greater than anything else we see and that's going to increase as time goes on black holes run into each other the entropy will go shooting it so it's not inconsistent it's not a paradox this picture what I'm telling you is what it's telling us is that the lowness in the entropy in our universe the thing that drives the second law of thermodynamics is gravity and something very special about the early universe and what I find very puzzling about this is why cosmologists that worry about it not just the fact itself why was gravity so differently treated than everything else the other puzzle about this is why as I said cosmologists don't seem to worry about it you can often see this is one of the remaining puzzles about cosmology and they've just all sorts of different things where is the fact that the universe seems to be so low in entropy in the gravitational field in normal things but you see I don't see any other scheme in cosmology which addresses that question other than I'm sure [Music] lovely let me just say well I'm searching something out about this you see it's really what drives everything about I mean why we here you see we're so the Centers of lower entropy each one of us where does that come from well actually it comes in the Sun and the Sun is a source people have to say it's a source of energy but it's not really this is a point made by Schrodinger and he got into a lot of trouble from being correct on this one and I say he was incorrect he said basically we don't get energy from the Sun because here is the Sun and we get photons coming from the Sun and they just go back there in the night they just go back again you see so you get as much energy coming from the Sun this goes up what global warming I suppose means a little bit more guest kept quality of it that in this picture is much less but the energy running out is about the same as the energy coming in but what's different is that the energy comes from the Sun in much much hotter individual photons and they it's blue yellow or something photons coming from the Sun and those going out infrared these are much less energetic individually so you need many many more of them going out to carry the same energy so you have a relatively small number of photons coming in relatively large number going out and that's what the plants make you serve and that's what animals make use on what we mean we make use of more many plants around them wasn't whether it is and that what keeps us going that's what keeps our entropy low is the hand sanding of huts in the dark sky and that comes about because but there are nuclear forces and so on important and Keating is ongoing but the main thing is that it's there at all and it collapse out of some gas that was our uniform spread and then as fun together the interview went up but there's a big large reservoir in the uniformity of the matter which is what this whole process is making use of so we need to understand that the key problem is to understand why universe was so uniform and therefore solo yes so there's my picture I see that's one roughly speaking the picture and it works because the initial universe was nice and smooth and was not this horrible mess which as I said was likelihood of that initial situation as opposed so we should be see not bad but we see this now you see a lot of time in my early days trying to characterize the Big Bang I came up with the thing I thought the vial parature hypothesis that's a bit difficult to explain I've had tell you what my temperature is my former student and colleague Paul Todd came up with a much better way of saying what is what he says is the condition on the Big Bang for whatever reason is it you can stretch it out to make it some smooth like this it was just a mathematical statement he said okay that's a nice way of saying what we mean by the universe having low entropy in the gravitational field it's a nice geometrically way certainly and I think it was much better than my way of saying it so I'm going along this good way and more or less what this way says that you could even draw this conformal picture that you can extend it smoothly it is something but hard befores he didn't say what it was before it he just said that's a nice mathematical way of saying how smooth it is but what I'm saying that is yes there was something before it and that was the conformal a squashed down infinite infinity of the previous field something were might worry that the Big Bang is which hopped very hot very dense which the moat future is very cold and very rarefied but you see when you do this conformal thing and squash it it has this effect on energy and momentum so on it means hot when you stretch it out becomes cold cold when you squash it down becomes hotter again and so that all makes sense so the as far as the physics is concerned joining this very hot thing under this very cold thing as long as you're looking at physics which universe with just the light comes and that was that one there that's the physics of massless fitness bets to say without any any mass thing they don't weigh anything and this is the physics when you actually have to take mass into consideration the equations of Maxwell always subscribe our light behaves have a property that you could stretch or swatch you could squash his friend they work just as well this is also true of what if all the yang-mills equations if you have got them as classical equations don't worry about quantum mechanics and you worry about the massive particles involved as long as you're just looking at those forces again it's true apart from quantum mechanics things to worry about classically it's just the same this is a squatch stretching and squashing you don't notice the difference it's things with mass that do notice the difference and that could be mass itself or it could be gravity because the source of gravity is mass so when you're talking about Einstein's general relativity couldn't be little careful because that is not invariant under removing the scale so that's something okay well two questions and some of you might worry quite reasonably that if you've got a theory in which like this what what's a cyclic model where things overall don't change very much each yarn is supposed to be roughly speaking not details then that roughly speaking over all the same now how does that square with the second ortho its limit because the entry is going up and up and up how do you make sense of that and they see that worried me for quite a bit and I thought there was some little catch about the face basis and things like that no that's not the other I should say totally accepted by people I hope they will be eventually but the point I was making is invasive them are while ago that the major contribution to the edge of the universe is in black holes by absolutely an enormous factor and remember what happens to the black holes well they eventually evaporate away but what happens to the entropy what happens the information like well here I have to appeal to one of the two Stephen Hawking's now when I say two there was a Stephen Hawking who initially put forward his theory of the black hole's radiating away and that in the year at that time said that information is swallowed by black holes it's lost like those he then in a later time changed his mind and said no no the information somehow has come back again no keeping take science on that I think he was right the first time and I think the evidence that he was right first time is pretty strong I know of other people argue the other way and I would think probably most physicists who think about this I think the other way around that the information must be regained but that's because you main reason they think that is because there's a fundamental principle of quantum mechanics which tells you is called unitarity which basically one of the things that tells you is that you can't moves information to study there's someone but you're the charity is something which is violated by the way we use quantum mechanics when you make measurements so you have to worry about this and that's a long story which other ones are going to hear but I think one can make very cogent pleasing arguments that information is lost in black holes as Steven said and it's very crucial to this picture is lost and as I said before that's where most of the entropy is in the universe as we know it now and so when those black holes disappear the effective entropy comes down other things really is a little bit subtle here because the entropy there's not a violation in the second row you see the second law of thermodynamics says that the degrees of freedom or more as time goes on and so on that's okay if you keep track of all the degrees of freedom but if they get swallowed up by a black hole you've got to start again and say do we consider those degrees of freedom to be important in our calculation if you said yes we do then the entropy is still there yeah if you say well look I'm not interested in those in the MOU because they've gone down the hole of the black hole and so they're gone so when you change your mind about what you mean by entropy and so it's that change of mind it's quite subtle thing that's changing mind which allows you to say there's no violation of a second or here because as you get close to the crossover between EC on in the next then you have to decide what to do with your definition of entropy Xin well let's forget about all those black holes that God the information is being lost in them and therefore what we used in measure of entropy has gone that it's not there's any violation of the law it's just that what we regardless the entropy of the universe you've changed your mind on what it is or you renormalize it anyway so that's that's the first point I want to make the second point I want to make is is his scheme true or not well I gave lectures on this for a long time thinking he didn't matter you know I would never be contradicted because nobody would ever know but then I started to think of the possible observation of tests which is but let me explain the first part yeah that's not the main point of this talk but the first idea I had as I mentioned you see black holes running into each other swallowing each other up getting bigger and bigger and bigger and then evaporating away so what happens when they collide with each other well there is a lot of radiation coming out in the form of gravitational waves if they went through this room you probably wouldn't feel a thing they don't disturb most things nevertheless they would come up to the crossover service this picture here this is supposedly the eon prior to ours is done here are eons in back that's our past like oh that's what we see is information coming from here and these are some black holes running into each other bang bang bang these are gravitational waves and these gravitational waves cause signals that we should be able to see I'm not gonna talk about the signals here although there does seem to be good evidence that they are there I have a medium colleague quite a versatile and we but paper received to see pretty evident there there mainly because they're so unruly formally distributed over the universe which is hard to explain inhale the way that these signals I should say the other is my polish group headed by Christoph Meisner in Warsaw and they in their first examination of the W map data's reserve satellite which looked at the microwave background of details that are coming in all directions and they analyzed the data and came to the conclusion that these signals are there with a likelihood a confidence level of 99.4% okay I think it's 99.4% but subsequently there were some other observations and that's really what I want to talk to you about it was part of the whole program of looking for these signals but still has to do with black holes here this one is to do the black holes colliding with each other and these signals coming out which I claim that was pretty good evidence the signals that there which contradicts particularly what the Polish people have seen and there at 99.4% there's a one- trance effect or something but if it's a chance effect the probability of it being the chance effect is only about 1 in 1924 so it's more likely much more likely about be a real effect but people have not paid attention to that and marginal serviceable but here's something else and I had thought about this before but it disturbed me and so I didn't think about it much more what about these black holes these huge ones which has swallowed up most of the matter in a galactic cluster and they're sitting around there forever went up my throat for ten to the hundred years or something like that all along probably won't that really be quite and they sit there and they sit there and then they gradually evaporate away according to what happens to all the energy in that radiation well first of all it's extremely cold that radiation if you have ridiculously cold I'm saying before but nevertheless you've got an enormous length of time you know all that energy coming out you see of course this is a kind of space-time geometry but nevertheless as you get pretty close to the edge then the radiation coming out will be concentrated spotless so even though it's a very low intensity it's all squashed down to a tiny spot so the entire mass energy of that vast black hole which is swallowed up always styles and things in that huge cluster will be burst through them and they will come true according to the scheme you see here we have the crossover surface between the previous ETA on them ours what if I draw here well this is what's called the last scattering surface you see when the microwave radiation is produced the thinking we see this radiation coming from all directions which I talked about before that didn't come really from the Big Bang it came well about 380,000 years after we've been that seems to ask quite a long time at cosmologically that's quite a short time but it means that the energy coming in here in this picture is correct was spread out to about four degrees in the sky how big is that when the moon is about half a degree so four times that saw eight times the diameter of the moon so these individual points these are what I call a bulking point because this is the Hawking radiation concentrated in that little point and then it spreads out to a much more uniform distribution but I should say the temperature variation from that we see in these spots I should say we see the spots if that's what we are we see these spots which are of that sort of size and that's one of the critical things but they're not bigger and they're not smaller there are they could be a little bit smaller because when we look back we may just catch the edge of it so maybe through from about two degrees across to about four degrees of course you should see according to this theory the spots which would be the radiation spread out from Big Bang to 380,000 years as to what we actually see in the microwave background now how much is a change in temperature there well I mentioned for the temperature variations are usually see that's the normal things that people see about one in a hundred thousand so that's pretty small this is about more than ten times as much so you see a variation in temperature which is a lot more than the general amount you see why having people see these before because they haven't been looking there seems to me a view that the universe ought to be very uniform and there's a lot of things like this you have to be a bit careful because the analysis that was done I should say this is a paper which is on the archive now by Christoph Meisner Daniel and he's a crystal meissner's published Daniel on who is a Korean works in New York who's actually done the detailed analysis of way this is called Planck satellite information like satellite and have them Russell is another polish and they person they've all been working together in this work now what we seek to see and I shall give you this picture here which is see see this is the black hole as far as all the gallery that cluster up it so it's actually hugely massive and then is eventually just underneath here it spreads up to about this big banner the Hawking point is there it's President to the size of about eight times of arms with the report away time say damn people and that's what we received the details here but it came out first because Daniel had done how do you know affect and effect is real you see what the standard way they will do it you see we don't know probably if we only have one universe so if you see something is there something unusual or isn't it well the way it's normally done I mean one can argue about these things but it seems to be quite reasonable as you make of some kind of a fake sky which is not the real sky but agrees with the real sky according to this picture here power spectrum let me not say about whether this detail but it's something to do with the distribution of irregularity ISM that you over the sky and you have some overall measure of any distribution do you think you'll ever touch them they're supposed to feed that in that you randomized within that constraint so you use that from the real sky and within that you randomized and then you make zillions and zillions of these different fake skies and you see how many of them to see the feature you're looking for well first of all then known in the thousands of these simulations and this is represented by one you see a zero you see this is you look at how many of those fake skies see this feature this is you look for a feature these are different sizes of rings and so on that's what all these numbers are if you get their particular size which I'm talking about here describe him is a very crude picture since these are the two ones seem to see in effect this is I'm afraid that between radians not degrees with never mind before the four degrees across the skies about that and these are looking at these rings isn't seen whether the temperature goes up as you go in with and that's thing you see certain points in sky modes happens and the question is how unlikely is it that you see is fat well if you look at all sorts of other sizes in these rings and so on then you see these big numbers here yeah that was with his son thousands in and then it's done here and you see big numbers here these were the number of fake maps which shows the feature more strongly than the real sky and then he sees zero that means none of them saw this video at all so in this big skies you don't see the signal so that means it's probably real well we've complained about this and said well good there's more because maybe there's something called looking elsewhere effect this means maybe you were looking to carefully them so he did another he didn't he did what was imagined he did he did the thousands and then eventually nine thousand more such ten thousand all together well you can see for one of these you see two and for the other one and the numbers have now gone up to the thousands so this means what it means is that this signal but could be a chance effect but the chart says it's a chance effect is gonna give you a bigger it's from nineteen nine point nine eight ninety nine point nine eight percent confidence level so that means that one can accept that this is a real effect with probability 99.98% correctness so I think people also pay attention to this if it's not this scheme that I'm describing and if it's something to be inflation what else it could be because we understand and there's a lot of agreement between the of observe calculations and what this is basically telling you telling you is that most of the time from the Big Bang until 380,000 years later the physics is extremely well understood because these things fit so well so that's very well understood it's hard to see how these signals could have arisen after our session between Big Bang and 380,000 years but what about inflation you see inflation was supposed to be taking place after the Big Bang now you see I'm not having inflation but the inflation were there then they hook in quite we have to be way down here summer and then the spread would be far more than the spread receive his breaks here who don't see the spread over the four degrees so that's a bit hard see they would have to if inflation was there the working point sort of they are would have to have been created just when inflation turns off it's what they call the graceful exit period which already is a bit of a problem because inflation is got to turn off the whole universe at the same time and that's referred to as graceful exit graceful doesn't suggestions or bangs here or huge ones I should say enormous explosions taking place in different parts of the universe we need an explanation maybe there is an explanation that comes about from some inflationary theory I await the first explanation at least we see an explanation on the scheme which I'd be describing today thank you very much [Applause] thank you very much for that very inspiring talk we have some time for questions from the audience we under audit very impressive professor I am just quite an iron question because of second law of thermodynamics what would be the future of the universe is another Big Bang boring but then that comes the next year and so it's not boring to things which don't have any mass because they don't experience that time so when you say the future of the universe you mean eg on that you mean the whole picture the whole picture just goes on and on and on so I mean you could have other views you could say when it stops somewhere well you could see these young changed radically in some way also something you even have a 10-round okay I'm not saying any of those things I'm saying at least my model is that it goes on indefinitely so the future of the universe in the sense of beyond there would just be continuing beyond like ours of course that's just a hypothesis maybe something else happens maybe a change in some way both are some horrible things because of I'd like to think of the simplest model in accordance with the scheme and that is that they just continue any other questions remain in your cyclic model universe is there a way how to say in which cycle are we now or now or how many cycles have there been so far not the same person if you go back in time was that her first one well according to Steve there wasn't Young's continued indefinitely I mean really putting this forward as the simplest hypothesis in accordance with a kind of mode that might be the variable in some way that the constants of nature changed from hell do we are and then maybe that was the first one the trouble there is we get back to the same problem that's where the first one health problem and things like that where is it escape there wasn't the first one it has in common you see when I first got interested in cosmology and I went to Cambridge to study mathematics at the time that I got involved with cosmologist then shamah particularly his friends with Andy and Tom ago fred hoyle and they had this model focused steady state law which had the expansion going on all the time - and one of the great features of this model of course that there was no beginning and they considered that this was a great virtuous I rather like the idea and then the thing was basically disproved because various things were difficult with it but the main thing was the microwave background and so the microwave background stay steady state all of us work so I accepted that Denis accepted it and so we have to be bad but this isn't a sense philosophically very similar to the old steady-state model is to say all the time but how far back ago there were these eons they don't be right the evidence which I just presented today is only some indication that maybe there wasn't a young just before ours it doesn't tell you whether there was one before that one but it doesn't his resolve so this year is about where the first one came from because it wasn't the first one with you about the satisfactory answer is another question okay my question is just to reiterate basically are you saying that these flashes which you observed in the microwave background radiation did they originate or do the numbers indicate that it's resulted they the result is that they originated before the Big Bang and let me explain and according to this bubble you see one of the reasons that people in general inflation is a good idea I already told you something which I worried about the population but the reason that it's around as part of standard cosmology is that it explains a very critical thing about the temperature regulations I mentioned that the temperature variation the Cosmic Microwave Background is about one part in that's a tie so you see these slight variations in temperature and these parts any more than that I should say but it's roughly one part in 100,000 and they have a certain characteristic that was called scale-invariant so if you look at small or large regions the variation seems to be the same so this is a very important feature of the radiation and this is the reason the main reason I think the inflation is stuck with us as a central part of cosmology because it's the only model that seems to explain that or seems to explain that and the thing was that you seem to see this scaling there and expansion as I mentioned right in the beginning this is exponential expansion and according to inflation Theory there were these things called infra Tom's and quantum fluctuations and these implicants are supposed to produce the variations in the temperature in the sky but what I'm saying is it's something very different I don't have written photons because I don't have inflation but what I do have is this exponential expansion of the previous year but I need something in that in order to give these fluctuations and the argument from this follow I haven't talked about it is the dark matter you see when you look at the equations of cross over for money on to the next you find there has to be some new matter which is some scalar material it doesn't have the directional qualities but it only interacts gravitationally it's the form of gravity in a certain sense but this is his dark matter I call these things Airy bonds because I looked up and Wikipedia to see if there was a god which was the god of darkness first ten minutes there was no Greek god that there was an Egyptian mom called air boss and they looked up later and then it turned into a Greek god so I was happy about that because have more respectability I thought anyway I call these things Aaron bonds and these are advanced decay and they would decay the lifetime has to be something like 10 to be 11 years so we're looking at 10 times cosmological times each one takes that long but they decay regularly so there's some of them record earlier than that and these take part in this expansion and when they cross over that is the result of the case of these particles that would be in gravitational signals they would come up and produce these fluctuations in the temperature but that's a technical point which needs to be looked at more carefully I can't give a numbers there it just seems to me that on this model the variations that are seen in the extent of the months five variations over the sky in this model of course by Mary Brown decays in the eon prior to ours consistently you have this exponential expansion which is scaling variant given to us you don't use a music and you feel to produce it as inflation goes it's given to us in this model and so you see that it has this exponential expansion and the area under case should produce signals like this now whether they do in detail is something which requires calculation and some figures which I don't have is something for the future [Music] [Music] [Music] see I was saying that over the Megara time disappears when you have no mass if the particles around have no manners and several points above addressing that and listening to but that's the magnesium and it's not as though you still have a temporal progression in the sensory no we just passed past the teacher still distinguished so some people say well you have no time how can you say these things follow each other or something and a past the future what comes before what comes after is still there it's a question about how much how much time expires between other thing is that certainly started with you know the tree falls in the forest nobody's there that doesn't make any noise no I'm not saying that's taught the point is that the geometry the physics doesn't notice something it is you see if you have only physics without mass then large and small become equivalent and so the universe make an universe more or physically identical what makes it different as if you have mess around and then you have the potential for clocks but when the physics is devoid of any mass which is the argument of the remote future there's a misuse which I could address it as a people opportunity but once it becomes the void in mass then physically there's no difference between large things and small things and this control behavior which means no difference between large and small is something which we see to see the laws of physics once mass is removed and you see this particularly in the Maxwell equations make it small and in the end those equations if you regard this classical equations quantum mechanics present some issues which need to be treated but then big and small still the same we've got to those courses as well you have to worry about gravity but then gravity is what makes the difference between small and why the gravitation degrees of freedom get wiped out it's all to do with the way gravity behaves with regard to these conformal stretches and squashes but the idea is it's a physical fact in this model but when there is no mass around but physically the larger the smaller equivalent and so isn't it I mean some hard thing to get the mind rather than I agree it's probably one of the cosmologists don't like this model because it's it's familiar idea but it seems to me physically makes sense to say that once there is no matter around matter the sense of massive entities then you need equations to make sense of that that's another story too I don't have time to say all that I hope is reporting hi does this come scale invariance applies does it apply for black hole singularity can you just zoom it out like you do that for a bank the scale invariance for singularity in black hole if can just assume me that zooming like you do that for Big Bang thank you in fact that was very big part of the whole story from way way back I'm worried about this a lot the fact you know when when he was about singularities the sort of argument was well what happens in the black hole is more or less like what happens the other way around and the Big Bang and that if you have secret out is in one place you have them on the other okay that's all right for general animals but when you look in detail and what you expect to find in a generic collapse on a black hole it is completely different from what happened in the Big Bang so yes some in your point is a good one that the singularities in black holes although there's no rigorous discussion of what actually happens there certainly is the work done by the Russians but it's like oh we seem to indicate that in general situations you get extremely complicated behavior what's more important that the violent curvature which I didn't talk about gets enormous and so it's very very different from what happens in the Big Bang and this is all tied up with the second or thermodynamics we have very very conformally smooth big man for whatever reason and the reason I say is it's the continuation of it but you were previously on I'd like to see another explanation inflation doesn't do it we should say what inflation will only stretch it out like that if the universe is very special it doesn't work in general situations so there is something very very different about the singularity in the bank and what we expect to see like bones so if you stretch the black holes ones they wouldn't do anything with just big greatness you can't continue the black hole singularities and they can fall away the viol curvature which is a measure of the curvature in conformal sense is enormous as you get closer and closer to singularity there's no continuing that in a smooth fall away so yes I said here it's a good question I have heard that shortly before that of Stephen Hawking he worked on the problem of photon certain photon cloud created near the black hole from all the matter falling forth into the blackboard and creating does something like we can say a memory of universe can be can be expect or can be say that this and this object was what's called I think smarter smarter yes software oh sorry sometime I can be say that this software which creates probably something like the memory of the old universe can determine the quality of the known universe which is created this is I should emphasize disagreement with what seems to be a very prominent view amongst many physicists which is what you just described namely that somehow the information which looks I so it gets swallowed by the black hole if you talk inaudible diagrams and things like that I really don't see how it doesn't get destroyed somehow the argument goes it gets recreated outside the black hole now it's an argument which many people have pursued including as you said Stephen Hawking and collaborators that they believe that there's something that the details of what they call soft air but it doesn't seem to me at all plausible there are other things called the cold fire words represent another argument the trouble is there is a huge conflict between two of the basic theories of 20th century physics and this is a big conflict between the night stars general relativity which says we have black holes and they swallow and you open this think analogous structure and you see what looks like happening and it's this one evening information so that seems to be what we see and the other is quantum theory quantum theory is based on very big principle which is called unitarity that's another way of saying the Schrodinger equation and eternity you cannot lose the information and so you have this conflict do you stick to the fundamental principle quantum mechanics reserves unitarity or do you stick to what general relativity says someone lose the information of the black holes but it's not just about as brought up with general relativity that I think that once corrected that limit it's just that there's another problem with unit errors in any way because in ordinary quantum mechanics whenever you make a measurement in quantum mechanics or almost whenever you make a measurement you you violate your deterrence now this gets into all discussion and how you interpret quantum mechanics and so and so forth either of the opinion that the current quantum mechanics is is in need of replacement by some theory which takes into consideration the effects of gravity and at the same time violates new territory so once you're prepared to pirate your territory and I don't see how you can avoid it unless you're going to some scheme where many worlds things we have all different things happening all at once and things like that that's the only way you could get rounded as I can see if you once you still stick to your unitarity then you've got to have either followers or software that's right things like that which is somehow our kind to retrieve the information so there's this strong feeling amongst many physicists somehow you mustn't lose the information you better get it back somehow but it's very hard to see because if you get it back outside you violate another fundamental principle quantum mechanics which is called no cloning you're not allowed to repeat information here than here and so if an information is is they're approaching the singularity how you're allowed to repeat it outside it seems to me you're a serious problem with them so I'm afraid I disagree with these arguments we seem to suggest that somehow the information comes back software firewalls whatever it is it seems to me the general picture that one has been representing is correct information ok one more quick question thanks thanks for saying anything make sure I think I just discussed this but just to clarify perhaps entropy is variable right and you mentioned the rate of change or the progress towards entropy could you perhaps explain but is it is it oscillating or g3c no there's no I mean the world soon after Einstein's general theory tunity Friedman discovered solutions of the unsent equations and one of the particular ones was what's now often referred to as oscillating water so it expands out and then it collapses down again and then it bounces and was there okay that was a very clear solution to the equations but once you consider black holes and the second law of thermodynamics for Tolman has a beautiful model we're never quite - that'll change but that was only a very very tiny entropy increase effect once we know from the Hawking the next line Hawking formula how much entropy there's a black hole there's no way you do it just by something like about some moment I mean because the as it comes in well they're great congealing of black holes and the entropy is going to violently up because they mess with each other and then you've got to wipe them all clean and so again it doesn't make to me much sense to another model which has this incredible mess at the end and suddenly it bounces out into something smooth I should say doesn't make much sense to me but there are people who do in quantum gravity in particular where they consider somehow there was a bouts of some sort which I don't quite see how they the previous what happened before the bounds could be evolved of anything like the universe window nah it would have to be something very different so it's very different than this game I'm saying certain models which - that was amazing I don't see you have to make sense of them within this general scheme of general relativity because you get black holes forming an unbelievable mess at one end and a nice smooth thing at the next end and they just don't match okay I'm afraid that's all the time we have for questions right now so I'm well now officially close close the program thank you all for coming and let's please give one more round of applause to Sir Roger [Applause] [Music] [Applause] [Music] [Applause] [Music]

Channel: FMFI UK

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Keywords: comenius university in bratislava, Roger Penrose lecture, Roger Penrose speech, Roger Penrose conference, Roger Penrose Hawking, Penrose Hawking, Hawking Penrose, Penrose lecture, Hawking points, Hawking points lecture, penrose hawking points, penrose public speech, quantum spacetime, penrose quantum spacetime, cmb sky, hawking radiation, quantum spacetime 2019, black hole, cosmological constant, big bang theory, thermodynamics, space science, cosmos, physics

Id: LPSzTcyXU7o

Length: 101min 4sec (6064 seconds)

Published: Wed Mar 06 2019