Sir Roger Penrose: Faith, Fantasy, and the Big Questions in Modern Physics

good evening my name is dr. Eric Berry I am a professor in the Department of neurosciences here at the University of California San Diego and far more fun for me is I'm also the associate director of the arthur c-- clark center for human imagination and it's my great pleasure to have you here this evening for so many good reasons but the best part is that i like to get to talk about arthur c clarke and so to take the podium to do so so the arthur c clarke center for human imagination was established five years ago here at the university of california from the arthur c clarke foundation our mandate is to study and understand and make use of human imagination and so we are a center across the campus with professors from cosmology and visual arts and science fiction and even a few brain scientists to understand what's happening in the human mind with the acts of imagination we are what's called organizational research unit and so that makes us quite flexible but also makes us dependent on our fantastic sponsors and our government grants and corporate contributions for our research efforts as I mentioned we have cross-cutting and research and activities across the campus in all kinds of laboratories from exciting things like a collaborator of ours who is part of the discovery of plant exoplanets in the Trappist one universe to the fantastic art installations of our Center director dr. Sheldon Brown Sheldon the other fun part of the arthur c-- clark center for you met an addition is our outreach and we have had all kinds of different activities including our science fiction film festival and perhaps one of the most exciting ones that will be starting shortly which is the Clarion Science Fiction Writers Workshop I was very pleased to convey to our guest speaker this evening that UC San Diego you may not know has the highest number of awarded science fiction writers of any University in the world and a few of them enter in the audience tonight so with our clarity and science fiction writers workshop we bring young science fiction writers in who go through an intensive six-week program of instruction and writing critiques and reviews and many of them have gone on over the four decades of the last of which has been here at UCSD to write winning screenplays and novels and short stories so it's a super fantastic part of our Clark Center to to host science fiction which brings me of course to arthur c clarke and as i say i just love to talk about him i had the great fortune of meeting Sir Arthur personally at his home in Sri Lanka fifteen years ago and so audience participation time who can say in the audience that arthur c clarke changed their life that they read his stories were inspired by them you know the hands are going up there they go arthur c clarke including our distinguished guest speaker who told me of his own reading of Sir Arthur including his fantastic short stories the one you may well know is called The Sentinel which is what the science fiction movie 2001 a Space Odyssey was based on interestingly The Sentinel will have its 50th anniversary next year and watch out for arthur c clarke center special events around the the 50th anniversary of 2001 also yes exactly yay for sure even more notably is this year is the hundredth anniversary of Sir Arthur's birth and we have all kinds of activities especially coming up in the fall his birthday is December 16th where we'll be participating in a science fiction film festival giving the arthur c clarke center for human imagination award film award and all kinds of other events that we'll have coming up through the fall so please go to imagination at UCSD edu where you'll be able to see the announcements and links to many of the activities that we have and imagination dot UCSD edu thank you for the correction and so it's it's my great pleasure to have my co-director of the Clark Center dr. Bryan Keating in the Department of Physics here to introduce our guest speaker thank you very much it's a great pleasure to be here there's some seats in the front just don't take mine please that off or give me a good tip and I'll give it to you Selim I see too so it's a great privilege I am the token physicist here to introduce our esteemed guest speaker tonight sir Sir Roger Penrose who's the emeritus professor at the mathematical Institute of the University of Oxford he's won many awards and he's known for many many things I first encountered him at such an early age in high school that I was completely baffled by his work which I have here one of my favorite books of all time I'm hoping to finish it someday they if you don't know they sell Rogers books by the pound okay he makes makes a lot of money off these these behemoths and they're wonderful I was remarking today on how exquisite it is that he combines the two kind of hemispheres of the brain that were known for on the arthur c-- clark center for human imagination Arts and Sciences beautifully together where he synthesizes the works of art and as well as New Directions in in science ranging from mathematical physics pure math to cosmology to quantum physics and he although he's an emeritus professor he is still actively engaged with research and in fact he's you know spearheading whole new directions in the study of consciousness which is actually what brings him here in combination with this event that we're doing tonight he's had tremendous influence in addition to the work that he's done as an amateur on my opinion he's professional level artist but he inspired the works of MC Escher or I guess you might say Oscar but his works on so-called Penrose tiling it's just one of the many areas where you can see this influence that then extended to these beautiful pictures that I'm sure you've seen on your dorm room walls or your kids dorm room walls with angels and demons interlocking in beautiful ways that was deeply inspired by the work of Sir Roger Penrose I want to just quickly read a list of things that he does and he's known for so the first thing is that he invented twister guys ever played twister no he didn't do that invent the twist or theory I'd be far richer if he did he invented the notion of spin networks geometry while curvature hypothesis Penrose inequalities as I said Penrose which you can put on your Penrose stairs which he also invented and the Penrose graphical notation so many things singularities of space and time relevant to black holes deeply influenced and collaborated and still collaborates with cosmologists ranging from dennis sciama who's adviser to him many years ago he's passed away and stephen hawking famously and i think there was a cameo of you and in the theory of everything i believe not not with you but someone pretending to be you and maybe we'll hear a little bit more about that tonight so i think i'm going to introduce sir roger afterwards we're gonna have a conversation i believe the two of us may be filled a couple of questions and hopefully it'll be a really enjoyable evening so please join me in welcoming the fantastic incomparable Sir Roger Penrose [Applause] [Music] yeah that's working thank you back up yes I'm not very good at it either so no see I'm really good what did I just do there too many knobs on these things that seems right yes I think I can probably do the rest of it and none mustn't press why is that mustn't press it's ok long as I'm up here somewhere yes I'm sorry about that this is the title of my recent book with the Princeton University Press it's part of the title of this talk I should explain something about the title because I think the Princeton University Press it was in the early I think something like 2005 I was supposed to give these lectures and I think they woke me up too early in the morning or something like that and one of the title for the series of talks that they wanted me to give three talks and I gave them this talk this lacked this title here and it was a bit rash because most of the I think the three topics at least two of them the world experts were actually in Princeton and it was a bit rash of me to talk in this way I think they didn't come to my lectures so that was alright but anyway let me start with the fashion and that had to do with well let me first say and let's get this going so press the right button that's right one of the ideas of string theory which people say it's great merit is that it's a very beautiful theory or the mathematics is very beautiful and I should emphasize that the idea of beauty in scientific research goes way back so in the Platonic there's there's a Plato there were these perhaps a little before Plato there were these four elements and the four known regular solids were supposed to be the represent the elements so we had the tetrahedron the first one there which was fire and then we had the octahedron which was air and then the icosahedron which was water and earth was the cube and as far as I know it's not just oh I should say it illustrates one thing is when somebody discovered another one if there were five you see you they had you could always mold the the physics into agreeing with the theory so they had to think of another element which was the the ether or what ever made up the cosmos which seemed to behave a bit differently from what went on in the earth so that was alright you could have another element but so you can modify our theory if the theory produces something which wasn't part of the observations you just modify your ideas and put the other one in the only thing I know that this is good for apart from being nice and elegant is that you if you take a cube take two cubes and those represent two sticks say two solid things let's the cube and then you cut them up and you can make two tetrahedra sorry two tetrahedron that's right fire you can take two sticks rub them together and you make fire and the in you get an octahedron as well and that's the that's smoke so you could produce fire and smoke out of two cubes anybody's the only thing I know which you can actually use this theory for a bit so never mind it just shows that the idea of elegance doesn't tell you everything it can be an important ingredient so but it's not everything okay let me move onwards if I press the right button I hope I press the right one this time here we go now string theory certainly was had its origins in a very elegant idea I should explain what these pictures are these are meant to be Fineman diagrams and well if you're particle physicist time goes this way from left to right but if you're a relativist like me time goes upwards doesn't make much difference but but in you'll see that time is going upwards in this picture and what this refers torments to particles coming together making a third and then that's splitting into two others and here you have two particles and what's called exchanging a particle and so on now these are different basic processes that particles can indulge in that each of these diagrams represents a specific mathematical expression and that's fine it works beautifully well the only slight problem is that this is meant to be quantum theory of quantum field theory the only slight problem is when you have diagrams like this which have closed loops and it's the great strength is you can talk about these things that when you actually strictly use the rules for what these diagrams represent you infinity infinity isn't much use but they have all sorts of tricks for getting rid of infinities and that's part of the theories is full of these tricks for getting rid of infinities but it was suggested I think Nambu was my main person made this suggestion but if you imagine instead of these particles if we if we go back and think about the Fineman diagrams you can think of the particle in time as it's its history and time would be represented by a line so that's the particle moving in some way and then it does something that some other particles creates some others or annihilates them or so on but then you have a problem because you get these infinities and this comes about basically from the fact that you've got well you might say it's because you've got corners and things sorry I've got the wrong way and this idea of the string theory is now you might instead of a little having the particle being a point and so it's history is a line the particle here now wrong the particle here is a loop and so it's history is a little pipe and where is the thing I press to make this the light Gohan oh here we go that's right so you think of these pipes it's a sort of plumbing if you like these pipes joined together in various ways and it gives you a kind of unity between all these little diagrams because you can just stretch them and squash them and they seem to be the same diagram and then you have these things here which are these things represent what are called Riemann surfaces there's a very beautiful piece of mathematics and that was one of the appeals of the scheme it relates to a very beautiful piece of mathematics and because of these things are nice smooth pictures now you the claim is that you actually get rid of your infinities and that's one of the great strengths so when I was first introduced to this idea by Leonard Susskind I think it was and I thought it was a wonderful idea and indeed I think it is an amazing idea with lots of potential the only trouble was that it only worked they discovered that it only worked when the number of space dimensions was 25 and to me that we didn't know it was that's the end of it but say a little bit more about that because it wasn't the end of it for many people let me go on you see what do you do with all those extra dimensions well the idea was this that the excuse he was only three see three dimensions of space in certain instead of 25 or so four dimensions of space-time in 26 yeah oh it's altogether so so you have 22 dimensions extra and where are they well the idea is this sort of tied up in a little knot which is so small that it doesn't bother you and the picture is more or less here this is the analogy of a hose pipe and the hose pipe dearly I'm really not good at this but pressure exactly the right spot my son doesn't do that here we are there is a hose pipe so if you're a long way away from the hose pipe it looks one-dimensional because it's just yeah it's one-dimensional but if you get up close and you look at the surface of the host pipe you see it's got a two-dimensional surface and that extra dimension is small in the sense of it's wrapped up into something small and so you the idea is that on the macroscopic scale on a large scale it looks one-dimensional but really it's got extra dimensions and the idea is that this what you look at on the large scale is the four dimensions of space-time but when you look at it carefully you see a lot of extra dimensions which wrapped up in this little small thing and that you're supposed to get away with it for that reason now I had some problems with this because well I'll tell you the basic problem I had by relating this to something else which is useful for this talk I want to say something first of all forget about the strings and everything I just want to say something about big numbers well ordinary arithmetic first of all when you multiply numbers together you see let's take a to the B what does that mean it means a times a times a times a whether B is all together that's A to B now you can do something a little bit more exotic but I say a to the B to the C of course you could read that two ways you could be able to B to the C or a to the B to the C well if it was just eight of the way to the sea that wouldn't be any good because when you can Rises edge of the BC so it's a to the beat of the sea is what it really means so that means if you have a times a times a that many times how many times is it well it's P times B times B times B times word C of them so that's what it is now we have this sort of thing here this is if you just want to have ten to the hundred now why am I saying to end of 100 well this is what's called a googol and there was a mathematicians nephew I think who forget his name now who it like to have big numbers he was quite young on about ten or so and suggested that here was a really big number put down a hundred zeros like that I should say that this number does feature in the book because it's roughly speaking the number of years that it takes for a black hole finally to evaporate away according to Stephen Hawking's process Hawking evaporation so a googol years isn't it upon the length of time that the biggest of the black holes will live for and that's so okay so that's a useful number to know maybe but here you see then this nephew decides that wasn't big enough and he was the bigger number so he and his uncle decided eventually that well a good good thing would be a thing that they called a googolplex where the number of zeros was a googol so you take a googol zeros and this is 10 to the 10 to the 100 now that number is not all that big I saw Ron grim years ago and he knows of numbers which are absolutely stupendously larger than this but let's not worry about this for a for an ordinary person that's a pretty big number it does feature it's pretty small by comparison with something I want to say which is actually than the improbability of the universe in a certain sense so let me come to that in a minute you see the point I really want to make here is if you have double exponents a to the B to the C C is all-important and it doesn't matter a hoot what a is more or less and the here is an example this is the if you like the specialness of the Big Bang I want to say that the Big Bang as we see it is a very very special one and how special is it well it's roughly speaking one part in 10 to the power 10 I think I've got 10 to the power 10 to the 124 now one thing I want the illustrate is that it doesn't really much matter whether that 10 is 10 or e or 2 if it's true you see the number at the top hardly changes at all so I so it doesn't matter what the bottom number is much but the top number is all-important okay that's the main message I want to give you except to say that this improv ability of the universe it's if you in terms of googles I've forgotten I said Google multiplied it by itself a million times or something like that it's easy to see from here but let me not say it because I can't see what I've written very well done okay I want to know that these numbers become Infinite and some of you may know about Cantor's theory of the infinite I'm just showing you this picture to say you what it's not because this is one of the things about Cantor's infinite you can take the the number of natural numbers zero one two three four and that's the smallest of the infinite numbers and one of the things that Cantor's theory says if you have pairs of natural numbers that's no bigger than the number of natural numbers and you can see the pairs of them represented by this array here going off to infinity in both directions and I have these vertices of this lattice give you the pairs of natural numbers those are the coordinates and the thing is you can count them by going backwards and forwards like this and this is exact pattern and you can exhaust the whole lot just by Counting individual numbers so this is Cantor's argument for showing that there are no more pairs of natural numbers than there are individual numbers but you see this kind of counting is not very continuous because you can see if you if you want to go from this pair to this one right up at the corner you have to go all me down there and all the way back again and when they get really big you have to go in a long way and so that close numbers in the pairs or Coast numbers in them in the in a number that you're you see your numbering the pairs here and that's what I just say you count along these this zigzag thing the numbers can be far away even when when the when the pairs are close to each other so it's not very continuous in this sense so what I want to say something counting infinite numbers but where it's really continuous numbers and you want to make sure that that it really is continuous so this is the idea and let's say what I'm talking about here well you see first of all as opposed to the the the plane in the discrete case being no more than in the straight-line this continuous counting the the plane has more numbers in it than the line and the solid would have more numbers again so that I'm going to call it infinity or infinity to the one is the number of numbers in a line or number of points on the line continuous points on the line a to the B a squared a to the two is the number of points in a plane or a curved surface and age of the three is the number of points in a solid and a to the N is in an n-dimensional space you can make sense of all this I don't want to say it's just waiting of the hands it really doesn't make mathematical sense but you can talk about these infinite numbers and again you find that the top exponent is all important one and that has a role to play in what I want to say about string theory so I'll come back to that but first of all let's just say well what I mean here you see suppose I now count the number of functions and this first picture here is supposed to be discrete function so when I say function you could think of each point at the bottom can take all the possible values upwards and if these are discrete and if it's a upwards I think and be this way then the number of different graphs you could have is a to the B that's just ordinary discrete things but what I want to say suppose it's continuous curves now then I would write that you see the number going up this way that's just it's just a lines I've drawn it but it might be a high dimensional space so the number here number of different graphs here would be AZ the sea and so on so let me show you an illustration of this which is some if I can make this thing work see suppose you have magnetic field or electric field say in 3-space and how many electric fields are there in 3-dimensional space whether each point you have the electric vector so you'll that little arrow they are supposed to represent the electric vector and you need three numbers to describe that vector it has three components and then I have the three-dimensional space so how what is the number of different electric fields well it's infinity to the 3e to the infinity here that's the the line which I'm supposed to be indicating bottom line that's right so infinity to the three infinity to the three infinity to the three they say it's the top three the trouble is these threes represent two things it's a top one it's the dimension of the space and what I want to say is if you have a say infinity to the a to infinity to the a infinity to the B to B there's a C at the top you finished you to see the C is the all-important one and it doesn't matter much what the other ones are so so that's the point I want to make and that's the dimension of the space so it's the top three here which is all important now why am I saying all this I'm saying all this because if you have a space which has more dimensions than three then the number of functions in that space is huge absolutely huge by a comparison with the number of components so you see you might have a field which had a certain number of components but if it's in a large number of dimensions it doesn't matter of hoot what the number of components is it's the dimension of the space which dominates everything so this was a reason why I didn't like the idea of more dimensions of space then we seem to see because that means that the functions in that space if it has more dimensions will completely swamp what we see and so why don't we have all these degrees of freedom completely swampy everything flooding space and that would ruin the whole of physics now the sort of argument that people made here and let me go ahead well here's the point I should have given this slide here you see infinitives a is larger than infinity to B or infinity to a I can't read what I've said that make you can read what it says there if the B is if the B is bigger than the D then it doesn't matter what a and C are so it's the top exponent which is the important one and that's the dimensional the dimension of the space and it doesn't matter who how many dimension how many parameters that are how many degrees of freedom you're talking about if the space dimension is larger is going to swamp everything now that was the point I was making but then people said well me there's a history to this because there was a wonderful theory put forward by Kaluza who was well whether he was German or polish depends on he was born in the country in a place which is not part of I forget to which way around it was it was part of Germany is not part of Poland or the other way around but anyway you could take your pick but he proposed this wonderful idea Einstein has recently introduced his idea of space-time in which you had a curved space-time I should say in which the gravitational field was encapsulated in the curvature of this space-time and the idea was could you do something better than that because you don't want just gravity you'd like to have electromagnetism and Colusa had this wonderful idea that if you introduce an extra dimension so that space-time is five dimensional then you could incorporate electromagnetism and couples with gravity in exactly the right way so that was really really remarkable so people say well five dimensions is good why not hire them dimensions but there's a key point here and that is that Inka Lutz's theory you needed to have a symmetry so press the wrong button again I'm going to do that I'm afraid you need to have a symmetry which is you see these here is space-time as we know it so it's four-dimensional and then we have these little curves a sitting over each point you mentioned another curve so the whole thing is five dimensional but because these curves have a symmetry you can rotate it round in that extra dimension that's not really an extra dimension it's an extra dimension which doesn't carry any more information so it's alright to have an extra dimension because all the fun of the functions on your space are down here not up there so that's fine fine changed the idea a little bit by making these extra dimensions mall in the way that string theory does and I don't know whether he was allowing you to have extra freedom in those dimensions or not it was the drama of what's a bundle I don't think I should talk about this it'll take too much time this example what's called a fiber bundle and you want to say that the freedom is in the bottom not in the fibers it's not you have a symmetry what people used to say to me when I complain they say well why don't you see all these extra dimensions how do you get keep them hidden and the argument was as follows well you can't excite those extra dimensions because it would take too much energy the amount of energy would take to excite the smallest mode of excitement of those extra degrees of freedom would be something like the energy in an artillery shell and you've got to you they imagine you say you're doing this in a particle accelerator and that accelerator has to give that particle that much energy that if it was in this room it would would be disaster for us I'm afraid but so that was the what's called the Planck energy and that well it's actually not quite that energy but never mind about that energy which would be ridiculously large so the argument goes well it will be ridiculous and the point if for me is that that's ridiculously large for an accelerator yes but that exciting that extra dimension is for the entire universe so that matter of energy and artillery shell for the entire universe is as a chicken field and you consider the amount you me you might imagine here this is my picture where we've got the earth in its orbit around the Sun and the amount of energy in yes orbit around the Sun it is million million million I forget how many millions it is more than the energy you need to excite that extra dimension so if that energy is spread out over the Earth's orbit let's say it's a ridiculously tiny change to this and so there's no no reason whatsoever as far as I can see why you couldn't excite that extra dimension and it wouldn't it would get excited and it would also be disaster because you can choose singularity theorems that's Stephen Hawking and I prove to show that the that it was not just excite that it would be a catastrophic collapse in the in the extra dimensions and so the whole thing would go to pieces well anyway that would that was my argument against all this and I actually gave this argument in a conference just a little bit before I started lecturing in Princeton I think was a year before and it was one of Stephen Hawking's birthdays have come from somewhere else first it was only the last talk of the conference and I was a little bit worried that by giving this talk I might be tarred and feathered because there were lots of experts in string theory in the audience and although I escaped with me out being tarred and feathered the next day there was a meeting for a sort of more popular conference and I was wondering well what people weren't worried about my arguments and Gabriela then it's Jana who is a real one of the originators of the ideas of string theory came up to me and complained about something the world about what about this one and I didn't mean that I see he said I like him a lot he's a very nice fellow and then Michael Green came up and he said well what's wrong what you've this you haven't taken no no no and then Gabrielle said him no no he did it he didn't mean that he meant this and they start arguing so that's why snuck off and let them argue it was an interesting day because I sat down at for lunch afterwards I sit down in this table and when he's asking came and sat down obviously he was the one who initially inspire me to think about string theory as a nice idea and he sat down and I'm trying to get the wording right it was something like this pretty well word-for-word you're completely right of course but totally misguided and I wasn't never quite sure what you meant but I think it was something like don't worry about detailed mathematics we know what we're doing and forget it but I don't know if that's what he meant but it was a curious comment I thought but anyway it's very curious that I gave this lecture it was written up no comment complaints of any kind no suggestion that the argument was wrong no suggestion of anything else about it no saying oh dear yes that's a problem nuf absolute silence and then also this has been true with this book I haven't heard anybody complained about my argument in there it's in the lectures of Princeton nobody complained about it and I haven't yet have a string maybe a string clearing theorists and the audience who wants to complain to me about the argument but it will be interested I'd like to have complaints actually because otherwise I have no idea what people think about it but I can't see what's wrong with the argument myself anyway let's move on this talk is supposed to be not just complaints about current ideas and that was a complaining about string theory of it or at least the extra dimensions of string theory and actually after my talk at which was on the fashion the first talk in Princeton a worried student came after me and said what should I do he was thinking of working on string theory and he was a little bit discouraged but by what I was saying and the his thing was anything else he thought I might work well this I didn't say twister theory which is what this is a picture off which is what I was working on partly because it's a bit too mathematical and I wasn't sure that well it has also a problem which is still not totally resolved and perhaps I well let me say in my book I do have a little section on this stuff so this is the picture from it in fact all the pictures are sure you are from the this is a picture of twister theory roughly speaking and so just to tell you what it is I'm not telling you any and what you used it for anything here but it's a it's a nice mathematical picture of course that doesn't mean it's useful in physics as I've emphasized before but the picture on the left is meant to be space-time so you think of this as a four dimensional picture of course I'm not drawing all the dimensions and here's a point down here is space-time or that's what we call an event and this is the light cone of that event that's all the light rays which you see a light ray here's a light ray up there you think of a particle moving along with the speed of light so it would be a straight line in this picture and the way you draw it is the speed of light as though it was one in the picture so that the thing is at 45 degrees represents light red and what twister theory does for you is the following the light ray is to be represented by a single point in a new space and the point over here you think of all the light rays through that and so this is this you see each light suppose you're sitting at that point you look out at the sky all the photons coming you for all directions is the celestial sphere and that's celestial sphere as nice mathematical properties it behaves like a complex one-dimensional space I won't go into all this because it would take me too long I just want to show you that there are things you can do using beautiful mathematics and they seem to me to be much closer to the idea of physics because you'd have the right number of dimensions that's what you see I should say that when people used to ask me why I didn't like how dimensions I had two reasons for not liking it one was the public reason which was more or less the reason I've given you that these extra dimensions you can't really hide them and how do you can't hide all those extra degrees of freedom and that was a main argument the secret reason was that Twista theory didn't work very well in that number of dimensions and Twista theory is very specifically designed to be a three space and one time dimension it really doesn't properly with any other numbered version you could start it but it doesn't get very far but it works beautifully if you've got three dimensions of space and one of time and then these ideas of complex geometry work very beautifully I won't go into this there are problems with it which I think we do know how to solve but they're but there's a lot of things we don't know how to do let me not say any more about that okay what's this we have talked about string theory and one of the complaints that people have I haven't mentioned but usually people who don't like string theory do mention is that it doesn't make any predictions and the usual argument is oh well you need all these artillery shell accelerators giving you an energy of that much to a particle before you begin going to test anything so they don't mind it being not testable because it's way beyond the scope of particle accelerators well what about the next thing which is the faith faith I should say is about quantum mechanics now it's completely different utterly different in the sense that where our string theory has absolutely no predictions which you are testable may have untestable predictions because they're way beyond the scope of what we had an experiment with these days but quantum mechanics has absolutely vast numbers of confirmations predictions and so on so it's completely different kettle of fish it is beautifully confirmed and one of the initial types of experiment that people talk about is a two-slit experiment very famous where we have yes I could master this the button which I have to press this to tiny from my thumb there we go this is suppose you have a couple of slits there and the screen behind and this is say an electron gun it's going to fire and nobody says you can see it far as electrons or some other particle say through the good they could be photons through The Slits now first of all I'm going to close one of it put a little cover on one of the slits and it fires through the other and you see what you get this sort of scatter picture the particles might get deflected as to go through the slit but there is a sort of little line which is the where the particles mainly hit but the scatter on one side of the other but a little bit of a you can see the indication of where the slit is if you close that stuff in there from the other one you have a very similar pattern but this is certainly pattern is moved over just a little bit because the slits in a different place but it looks just about the same so what happens when you open both slits you might expect that you get this picture plus that picture nothing of the sort you get these bands where some certain places where you find that the particle can't reach at all other places where it's more likely to reach them the big number two pictures added together so P and Q one piece of example of where are you whichever it is I can't see these things I'm sorry about that you can see them so you get places where you get these bands of enhanced and it makes no sense you see if a particle behaves like a particle why doesn't it just add the two pictures well the thing is this is the thing it doesn't just behave like an ordinary classical particle but it behaves in a certain sense like a wave and the wave is what gives you the bands so you see the particle behavior and the wave behavior both at once because you get individual points on the screen that's the particle behavior and the wave behavior is the interference so it's a very beautiful illustration of how quantum mechanics mixes these two ideas together and you have particles behaving as waves and waves as particles and so on now I'm not going to say too much about the way we work quantum mechanics but I will say something about it you see what's the what's this about when you see according to quantum mechanics it's not just true that individual particles could be two places at once she in order to explain the band's you have to say the particle somehow feels out both slits it doesn't just go through one slit or the other it seems to go out through both slits at once and that's it interferes with itself and some of the roots can enhance each other but the particle has to be considered that it goes through to it once and that is the way you do quantum mechanics crazy absolutely crazy but it works now this is an example my humane version of Schrodinger's cat you see it's the cat going the two slits you see so you could say why doesn't this work on a much bigger scale so what am I doing here this is the cat behaving like a particle going through two slits sort of and so how it what's the experiment here well I've got up at the top here back press the right knob and that's the wrong dog sorry about that don't know why I'm so bad at this okay you see here is it's what's called a but there's the laser which emits a single particle and then here we have a mirror where it's you might think of it as a half-silvered mirror or a beam splitters it's called that the the photon goes through it and is reflected at the same time so it shares its existence between those two roots and it there it is you see particles couldn't be to placed at the same time but if it goes goes through one is it activates to detect a detector which opens that door so if it goes down it opens the a door if it goes horizontally it opens the B door so if you follow Schrodinger's equation shrouding this equation has this behavior of being linear and that means that whatever if a does something or B does something that the superposition of the two must be a superposition of the two so the doors must be one door is open and the other door closed superpose with the other door being open and the one door closed it's a bit hard to draw all that but this is the if the photon goes one way it opens one door the others left closed it goes the other way it's the other way around and the poor cats sitting here it encounters this super Z well it wants to get the food which is down there you can see the food in the room and so the cat wants to go the door through the door to get to its food but since the cat is the doors are in a superposition two places the cat must be in the superposition so it's a superposition of two doors well Schrodinger's version was a little bit less humane than this one but the idea is that Schrodinger was demonstrating basically that his equation tells you nonsense his equation tells you that a cat could be dead and alive at the same time or in this case the cat could be going through both doors at once and that's what his equation tells him and so usually quantum mechanics people say well now you have to interpret it in some way which means you've got to make a measurement or something well why doesn't the cat itself make a measurement by noticing which door is open or something like that so you have a little bit of a problem this has I've been struggling with this for ever since I see when I went to Cambridge as a graduate student I went to lots of lectures what which weren't anything to do with what I was supposed to be doing one of them was a lecture brilliant lecture course by bondi on general relativity and that influenced me greatly and now there was a lecture on well on mathematical logic which led me to girdle's theorem worrying about consciousness and things like that and another lecture was a lecture by Dirac the great quantum physicist and his lecture was beautiful completely different from from Bondi's lectures was full of excitement of the waving of hands and all this sort of thing and Bondi's was very precise and very elegantly done and right at the beginning he gave a demonstration illustrating the superposition principle he said in quantum mechanics see a particle can be over here or it can be over here then it can be all these combinations have been here and here at the same time that's the superposition principle and then he broke a piece of chalk and said well it's an illustration is this a piece of chalk being in two places at once and my mind wandered at that point I don't know what I was thinking about and then he had an explanation why the piece of chalk was nothing the two places at once and I came back and I thought What did he say and I'm worried about that ever since we said something the word energy I think came in this somewhere but I couldn't see what energy had to do with it so I've been worrying about that ever since and I'll give you some bits of my worries here I think I forgot my live I have on these slides but I think that's one of them well you see here what's this about this is I could explain the origin of this picture I was asked by the Hans Christian Andersen society to give a talk they were just coming up to the 200th anniversary of house Christian Andersen and for some reason they didn't vitami is to give a talk and I was very puzzled by this because what have I got to do with Christian Andersen farah many fairy tales well then I remembered of course that I'd written this book with the title the emperor's new mind and this of course was a play on the emperor's new clothes which was a famous that's Christian Addison's story which very much was influencing what I was talking about in the book but I had to think of something else so I thought of well I thought of the mermaid you see this is the Little Mermaid story and in my lecture I related it to quantum mechanics in various ways well one of the ways was that the mermaid at the towards the end of the story she is can't remember why but the thing is it's in the night and when the Sun comes up the first ray of the Sun when it hits her she dies so I thought well why don't we save her by putting a mirror between that beam of first beam ray of the Sun and so I get reflected up into the sky and she's fine but then of course well you know what I'm going to do make it into a beam splitter or a half-silvered mirror and so the photon is split between going one way and the other so she's in the superposition of being dead in the life she's a Schrodinger's moment so that was that was one of the uses of a mermaid in this lecture I gave but does the feature in my book I'm afraid but it does feature here as an illustration of quantum mechanics so this is an illustration of where quantum mechanics is done so this is really what it's about the bottom part of the picture represents the quantum evolution the Schrodinger equation if you like u stands for a unitary evolution and this is Schrodinger question it's a deterministic evolution of the quantum state so it chugs away and you could put it on a computer if you want to it's rather hard to do but you can put it on a computer and that is the quantum world what's at the top well that's the classical world and the letter C is being used here for classical world and the quantum world you see everything is all a bit of a mess and tangled up and unfamiliar creatures and who knows what's going on there and it's very unfamiliar looking world but then we have a more familiar world at the top where things are separated and so on and watch the mermaid doing well she of course is partly in the quantum world and partly in the classical world she's magical too so she represents how somehow the classical behavior comes out of the quantum world and the way that occurs in quantum theory is by another process which is called the collapse of the wavefunction or the reduction of the quantum state that's our in the picture where suddenly this great entangled mess of things you do what's called making a measurement or something what it means is a little obscure because when you make a measurement you've got to use a piece of apparatus if the quantum world is everything then that quantum that piece of apparatus which does the measurement must also be part of the quantum world and so why isn't the bottom well that's never explained but there are all sorts of partial explanations which people give I don't believe any of them but something must happen and I think something that happens is something mysterious like this mermaid but not so mysterious is that won't be part of a future physics but it's not part of the physics that we have today because the part of we have today is either quantum or classical it's quantum it belongs to this what modern world and you get these super positions of cats going different doors and so on if it's the top world you get going only one door not the other and that's what you see up here and how does that work well how we do quantum mechanics is illustrated more in this picture this is the graph well I'm afraid I'm doing the Condor the particle physicist I'm going horizontally when the quantum state is represented by upwards so the quantum state evolves according to Schrodinger's equation or U and then somehow a measurement gets made and one of a different set of a number of set of alternatives comes about and then that evolves and then one of them comes about and then that evolves that's the way we do quantum mechanics looks completely crazy because you know there's another systematic system to the whole thing but that's the way we do quantum mechanics you plug along with this unitary evolution and then sudden you change your mind and you take it as representing a quantum sorry a probabilistic or a set of alternatives one of which takes place some theories say well they all take place and you get all these many worlds happening all at once but I wanted an explanation which describes the world we live in and that's only one world so you need something which really this is an approximation to it's crazy as a theory as it stands it's the way we do quantum mechanics but we want a new theory which really makes sense of it so let me try and go ahead without making a mistake now this here is the course an illustration of what I think gives a reason for a new theory or at least its reason for what it might be and I'm trying to explain I don't think I can explain all this here but let me just show you I like the picture because when I drew it you see I do these pictures and they were sent to the man who did the looked at them and said whether it was good enough for a reproduction and so on he was supposed to improve it but I ended up by improving in myself because it was easier but he thought it wasn't going to work very well because this picture of the table you couldn't be squared will see the dials and all that and it needed a little bit bit of clarity well yeah when I had to explain him this is a completely fictional piece of Epirus done me a damn thing so I just I just put it up there so you could imagine some complicated piece of apparatus and the point is it uses gravity in it somehow the Earth's gravitational field is incorporated in the quantum system you're describing and the point I'm making here as there are two ways you can consider the Earth's gravitational field one is the ordinary way that almost physicists would use and they do what's called putting a term in the Hamiltonian to represent the gravitational potential I don't if you don't know what that means it doesn't matter but that's the standard way and you can do that but that's only Newtonian way and we don't believe that the Newton way is the right way we believe that the an Steinem way is the right way and the ice standing way is to regard the gravitational field is equivalent to an acceleration so you imagine yourself falling in the gravitational field and then you your coordinates are this falling free three field and then you do it this way and you find almost the same answer whichever we do it but there's a technical point which I don't think I can explain but the technical point is that the almost isn't exactly the same answer it tells you it's fine if you just took one gravitational field but if you've got more than one gravitational field you're in trouble when I say you're in trouble it means that you can't actually apply the quantum mechanics it's you have to do something illegal according to the rules of quantum field theory let me not go into any detail there but it points out that if you have gravity in the picture you've got to think of something else quantum mechanics doesn't work if you incorporate it with the Einstein equivalence mr. Galileo Einstein prints equivalent principle which says that a gravid uniform gravitational field is equivalent to an acceleration and that causes problems and this is the pictures you're into illustrating the source of problem you have here we have at the bottom a lump of material not and not have anything as complicated as a cat it's a lump of a stone or or something which is put into a superposition of two locations and then upwards we have now the picture of the space-time or did I am doing it a picture of the space-time and these are the different accelerations you have you see and the fact that the the black one gives you the black curve for the accelerations and then gray one is the gray curves and the fact that they differ means that you if you're trying to do the freefall argument you're in trouble with trying to make them match and that if you look at this carefully you can see it leads to a conclusion which I've Illustrated here this is a picture of what happens to the space-time I'm afraid it's a little horrible looking picture but never mind that's the claim that what happens is something like this you have here it's really the picture I had a minute ago with the two space times but the two superpose space times have to come about because the rocket gets moved into a super position and so initially the the rock is in one place and this is the curvature it introduces and this time evolves the rock moves into two positions superposed and so you have two space x which is superposed and the thing is that there's only lasts for a certain time which you can estimate but in terms of the energies involved in the displacement here I won't go into the details there but but there is a well-defined formula which tells you how long it could last and this if there's a big displacement of mass down here then it's a very short time if there's a little displacement it could be a long time and it's such that the space-time displacement is what we could say one in what are called natural units that's where you put Planck's constant equal to one the speed of light equal to one and this and the gravitational constant equals one you can just just go the way we're doing all that and if you do that then one unit of time tells you how long it takes for this to take place I wasn't saying anything about consciousness in my book except a little bit I'm talking about this but this does relate to the ideas which Stuart Hameroff and I have been trying to develop what we call the Orko our theory because it makes use of this idea where there is this choice that the universe seems to have to make it does one thing or another and that is the choice which is made in this time you can estimate from this picture and the idea is these choices are taking part not just one displacement but there could be lots and lots of mass scattered when that scatters is the wrong word in an organized way over the brain in these microtubules is the idea and the amount of you could calculate how much energy how much mass there is displaced and that gives you a time scale and the idea is that a conscious experience comes about with this kind of choice that is made so if there is a notion of free will it's related to the choice that the universe seems to have to make whenever this measurement or whatever it is self measurement takes place okay well that's a little bit of speculation there but we do have the point about this is that it is experimental testable well I mean what's experiment is testable if you like is the idea that I'm describing here and here that this reduction takes place in the time suggested and this is a cartoon of an experiment which was being worked on for I don't know about a decade and a half or maybe two decades by now primarily garbed dick Baumeister who this is an idea that we developed together with some other people that you have say there's a laser here emitting a single photon and this gets split into two directions and this one is kept in what's called a cavity and it reflects backwards and forwards like this probably about a million times this one has a funny kind of cavity where reflects against a little tiny mirror here which is a little cube which is about a tenth of the thickness of a human hair and if it gets hit a million times by this photon it will get displaced by something like the diameter of an atomic nucleus but the idea is that that should be enough if this scheme is right within a period of seconds two minutes depending on details decay into being one or the other so it's in a superposition of being hit by the photon so it's displaced and that's when the photon goes this way if it goes the other way it's not this place so that it's a superposition in one place and the other and that superposition the claim we make is that can only last for a certain length of time and if it becomes one or the other in that length of time you try to bring it back and you'll see you've lost coherence and this detector up here would see something whereas if it didn't lose coherence it would go back into the laser and you wouldn't see it so this would be a test for whether this is right or not so be very interesting to see there are other tests that just have been suggested more recently before whether that will happen okay cosmology this is the last this is the fantasy now a little little bit of a different story here because I was really aiming the chapter on the third chapter on inflationary cosmology because the normal picture that we have today of cosmology is a bit like this thing here time is now going up the picture in the way I like and the time is going up this way and this represents the entire universe well where you might ask what's all the frilly stuff at the back well that is just because I don't want to prejudice the issue as to whether the universe is open or closed it might go and do something at the back or it might close up on itself it doesn't matter much for what I want to say it's easier to draw the picture if it's closed now this is the history of the universe Big Bang Inc expands slows down a bit and then idea no but it slows down a bit and then it does this exponential expansion which was got the Nobel Prize recently the universe seems to be doing this accelerated expansion people refer to it as dark energy or something but it seems to be consistent with the term that I introduced Einstein is reduced into his theory of general relativity initially in in 1915 and then he introduced another term in 1917 for the wrong reason because he wanted a static universe and then he got worried because the universe was observed to be expanding so he regarded as this as his greatest blunder to introduce this term but his greatest to say is that this term was his greatest blunder it was actually a blunder because it actually seems to be true so this is a rather curious that I son introduced it for evidently the wrong reason but it seems to be the right theory ok so that's fine explains this picture beautifully but what have I left out I seem to have left out a major part of the theory which is what's called inflation so they're supposed to be tucked well you see I could should say wow dear really bad this is sorry it's tucked into that little black point there so inflation might be in the picture you wouldn't tell because on the scale of this big it's pretty well to scale but the scale of this picture you it would be tucked into that little black spot in the beginning but the other reason it's not there is because they don't believe it well I don't believe it originally I didn't believe it because it looked very artificial and this is a picture one of the reasons I feel it's artificial because well you main thing that the inflation depends upon at least the modern version a thing called the in photon field which is a completely made-up field and it's got a potential function which is represented in these different graphs you have to draw the graph by hand basically so that it does what you want and this is just the sample of different graphs of what the in photon field is supposed to do and it shows you that nobody has a very except that it's got to have a general picture like this to do what you want it to do but it's a made-up feel and there's no reason for from particle physics to believe that that field is there but it's supposed to do various things which I didn't believe it did one of them was supposed to do is to iron out the universe because the universe is very uniform the early universe is very very uniform and inflation was supposed to make it smooth now the pictures I've got here are various models of universe not necessarily with inflation in them but this is out there and really need I need a lesson on how's it going work these machines here we have the Big Bang sort of if the universe was closed it would look something like this with expanding out and then it might collapse again and produce a great mess but the great mess isn't anything like the Big Bang so this is a very general kind of singularity you get when it collapses and this is what we have now just reverse the time and this is telling you why if you have inflation it doesn't turn out this great mess the great mess will be inflation or no inflation you can see from this general argument that it won't hand it out ok well I shouldn't have wasted so much time on this but let me go on now you see there's another argument which worried me for a long time which has to do with this thing called entropy see entropy is a very fundamental part of physics it tells you a measure if you like of disorder so and the second law of thermodynamics is more or less a statement that the entropy increases with time or the disorder increases with time if you like oh it gets more and more random as time goes on the top picture is a nice illustration showing you the sort of thing that happens if you have a gas in a box you might have it cornered blocked off in the corner you release it and it spreads out over the box now the universe that we see there's a problem because if the second law of thermodynamics works way back in time to the Big Bang what you see is telling you that as you go into the future the entropy goes up the randomness goes up so that means if you go into the past the randomness goes down so it must be very low entropy in the early universe now what we see that was the main evidence for the existence of the Big Bang is this cosmic microwave background and the cosmic microwave background is this wonderful spectrum I don't think I've got this picture here because Micmac avoid microwave background one of the main features it's got this curve if you look at it which let me know explain is if it looks like this famous Planck curve and the point is it tells you that what you're looking at is maximum entropy now maximum entropy you might say that's ridiculous because it should be minimum entropy as you go back and back and back in time it shouldn't be a maximum because it's gone down and down and down so why is it a maximum well what you see seems to be a maximum well the universe is expanding so you might worry about that but that's not the answer yes it's clear you can give good reasons why it's not the answer that's not going to that there but the point is that what you're seeing is radiation from matter and radiation basically in equilibrium together so that is what's called a thermal state that's the maximum entropy state of matter and radiation and that's what you see is radiation from that what you're not seeing in that is the effects of gravity however there is another feature of the Cosmic Microwave Background and that is it that the universe was extraordinarily uniform in the early days well you see that would be consistent with the top picture if it's high entropy but you want low entropy so the matter here in this picture doesn't do what you want but if you imagine a box galactic scale box at least as just stars running around then the tendency would be for them to clump because of gravity and eventually produce black hole now you see that goes in the opposite direction so what you're seeing is great uniformity over the sky in other words you've seen combination of this and this low entropy and gravity high entropy and everything else now this seems to me to be an extraordinary puzzle and I never understand why cosmologists just cosmologists don't this is the big puzzles of cosmology they have a good nice list of things which are mysterious and this is never mentioned to me it's one of the biggest mysteries why is gravity so differently treated for everything else everything else was maximum entropy gravity was essentially minimal entropy and it's a huge imbalance now the scheme which I'm going to talk about if I push the right picture now this is actually just a picture showing you what this imbalance does you see when the initially uniform matter starts to clump it makes galaxies nice makes stars and it makes stars and it made the Sun and the Sun is what we rely on for life now you might say what do we get from the Sun do we get energy from the Sun well then you might think if the whole sky was the same temperature as the Sun that we're even better but it wouldn't be any use to you at all because it's not the energy that we came from the Sun it's the low entropy in the energy we get from the Sun because the Sun is out there and it's hot and you have a cold sky the earth doesn't get energy from the Sun if it did it would simply get water on after a few days we were completely intolerable they were just life would be impossible but of course in the night it all goes back again but it all goes back again in in low frequencies and it comes in high frequencies it's yellow lies and infrared going back basically and it's this large number of photons going up which take the entropy away and the low number which come in which comes in a low entropy for it's a point Schrodinger made a long time ago but it's it's not very much appreciated apparently but the point is that it's the clumpiness of the material which enables stars to get produced in black holes I'm not going to explain the black hole so much this is a space-time picture of a black hole and the horizon is this was a tube which comes up in the singularity in the middle but the point I want to make is these cone things what are these cone things these are light cones and you have to imagine that the space-time has all these cone things drawn on it which tells you what light would do if it were very you don't have to have light there but if it were there it would follow the cones and I had a little bit of this with my twister picture but well this represents imagine a flash of light the first picture is the flash of light in spatial terms with three dimensions they're spheres spreading out but then when you I've got to throw away a dimension over here so what looks like a sphere who looks like a circle here and so the cone represents what light would do if it were there and you have to imagine at every point in the space-time there is in the tangent space a little cone like that ok which tells you most of the structure of the space-time doesn't tell you quite the whole structure because it doesn't tell you how clocks behave it tells you if you know about general relativity you know that this thing called the metric and the metric has ten components and nine of them or really the ratios of the ten components tell you where that cone is so that's almost all the information the one missing piece is the behavior of clocks so you want to know how clocks behave and this is a cartoon showing you different clocks idaite identical clocks but moving with different speeds and the first stick and the second tick of the clock represented by these surfaces yeah okay now the clocks we have extraordinary good clocks now and the extraordinary the extraordinary precision of clocks depends basically the reason that it's so good in a sense the ultimate reason is because of the two most famous formula of 20th century physics these are one of them as to the Einsteins equals MC squared the other one is max Planck's e equals H nu or XF if you prefer F for frequency but nu is my frequency and if you put the two together you can just eliminate the energy from them see Einstein tells you that energy and mass are basically equivalent Max Planck tells you that energy and frequency equivalent it's put the two together it tells you that mass and frequency equivalent so you if you have a stable particle and this is the history of a stable particle it is a clock of extraordinary precision so this is indicating it's an oscillator it has a very very high frequency you can't use that directly but the good clocks that we have depend on this idea not directly here but basically the same sort of idea is that you have this extraordinary precision because of the combination of these two very very basic principles so quantum mechanics gives you these very precise precise timing of clocks now the converse of this however is that let me go back to this first then if you didn't have mass suppose you just had photons then they only travel a lot along the curl and they don't they're going on zipping along here and the first tick is never even registered so a photon doesn't feel the passage of time at all now why am I saying that I can actually forget with my pictures what the next slide is but I have the Escher picture what's there doing yeah I need that okay let's come to this first there imagine the very remote future I should be giving you my universe picture if you like the very remote picture picture and you wait for eternity that's a long time well you wait for first of all the the the glueball years for all the black holes ago that's the boring time when you wait for a black hole to evaporate away that's really boring but they're very boring after that there's nothing of any interest happening at all as far I can mega and but the I was sitting worrying about this in my office I think isn't that a dreadful fate for the universe just interminable boredom that's that's the fate of the universe but then I thought well who's going to be bored by this universe well not us but it'll be photons mainly and it's very hard to bore a photon it's hard to more a photon because well as Stuart will tell us it probably doesn't have any experiences but that's not the point the point is that the photon zips along doesn't even hit the first surface here it doesn't even notice the passage of time at all so it gets right out to infinity without noticing a thing so that's the main point I want to make and it's the sort of thing I used to play around with decades and decades ago squashing is finish you down and it was a good we're talking about radiation and black holes and the energy they carry away and that sort of thing which is very topical now but this is a very nice illustration of a particular type of geometry it's called hyperbolic geometry particular is a type of geometry where you can see infinity so here are these fish are supposed to be as far as they're concerned the same right out to the edge so the geometry they use is such that they're scale is you have to sort of rescale the geometry so that there are the same right away as far as they're concerned the universe is infinite and these even though they look to us is getting smaller towards the edge as far as their Jarmusch's can they're the same size and it's what's called a conformal squashing down and you can see that particularly in the eyes that the fish because they're circles and there remain circles will write the way as close as the edge to the edges you can get this as far as these fish concerned they like that massive particles if you like this is infinity the edge is infinity but if they were like photons they wouldn't care about the edge and you can see that things which just respect the conformal geometry that edge is just another place so the photons zipping up and that could be right out there so it's the same idea it's being used here now to talk about infinity of the universe so what I'm going to do is to squash infinity down in the same kind of way so what we have to imagine is that below this line I'll tell you what that line is in the middle in the minute but below that is somebody's universe let's say our universe and this is its remote future and as far as the photons are concerned this is just another place like anywhere else and so consuming along it says well where am I supposed to go after that so that's after infinity the idea is it's go somewhere else now where does it go after infinity well now we think now let's think of this as the top part of the picture now as you go back this is supposed to be the Big Bang now I talked about the Big Bang being a very very special state and I used to have some complicated way of saying that but my colleague Paul Todd must he was a student of mine a long time ago and a much better way of saying it he says just take the conformal geometry which means just take the light cones forget about the scale and the Big Bang the idea would be is a nice smooth surface which you could theoretically extend to before but why bother it's not supposed to be real it's just a mathematical trick so that was his idea it's also physically a good idea because you could say well it's not just photons as it was pretty well here but you've got all sorts of particles but they're very very hot and energetic and the closer you get to the Big Bang the more and more energetic they get so they're behaving like photons so they have effectively no mass because their energy of motion completely swamps there and their mass and so they're behaving as though they had no mass and so again they say well why wasn't there an existence for me before the Big Bang and that only works in these very special model as I say 10 to the 10 to the 120 for special these only very special models which seem to be what we seem to see is the universe like that so the idea is that the universe was of such a character that you could extend it conformity to something behind and then the crazy thought here now all this isn't so bad it's not totally crazy the totally crazy idea is my idea here which is to say okay this is May drawn a little smaller the picture I had of the Big Bang of the universe before with insects exponential expansion here that's us well we're down here somewhere and you squash down infinity to make it a nice finite future boundary like in the Escher picture you stretch out the Big Bang as Paul Tod suggest you do and the crazy idea is that they match well our Big Bang was the continuation of somebody else's remote future our remote future will be the Big Bang of somebody else I call this an hour yawn that's the eon but for four hours this is the eon that will come after hours it's a little bit shades of the steady-state model where we used to seem to have to have this continual universe well as philosophically like the old steady-state model but very different in detail so it's a this is supposed to have existed forever in this scheme and there are various nice implications of the theory has which are still being explored and I think has a good chance of being right there are the main observations I don't think there's anything more on this this picture so yes there's nothing more so let me just say there is a the question is could you imagine signals no dear I'm not pressing I've done a personal thing never mind could you get information through from one to the next and the claim is yes you can and I thought what is the most violent process that I could think of which might get through well I thought of collisions between supermassive black holes our galaxy has a black hole in its center which is about the mass of 4 million son four million times the mass of the Sun we are on a collision course with the Andromeda galaxy which has a much bigger one I forget I think 40 times as being a can't remember the figure but when we collide which we will do in a few thousand million years not that long the black holes will maybe miss the first that it probably missed but they may well feel each other out and eventually spiral into each other and there will be a one big whopping explosion and that signal will go right out and will be detected Tech table by people living in the EON beyond hours so I'm saying that we could detect signals like that in the eon prior to ours so it's a perfectly experimentally testable theory and the question is is it right or not well I'll leave it at that point thank you very much [Applause] I'm afraid I probably went on far too long but still just fine okay thanks yeah oh thank you yes thank you thank you very much yeah can anybody hear me in the back in the front well that was very nice sir utter that was quite thrilling to have you explain these concepts that have been so mystifying even to professional card-carrying physicists and actually do it in person and I was thinking as you were talking about eternity of Woody Allen's famous line that eternity is a very long time especially towards the end that's right it's not so long for a photo tell us things are very laconic mm-hm for photons so first I want to mention you I did I forgot to earlier tonight that part of the reason that you're here is to sort of kick off the celebration and this this initiation of a new center that we're forming here in the oil pan Rose Institute yeah one of the founding directors James Tague is over there in the front row and we're hoping to form a collaboration with the Clark center that will kind of spread the boundaries and increase the interactions to use the physicist language between the arts the sciences consciousness the squishy Sciences the hard sciences the life sign I was like when they say life sciences because that means that physics must be a dead science the opposite so I wanted to take take the opportunity thank you for being a part of that and we're looking forward to many more fruitful collaborations and interactions to come I wanted to start off tonight with a couple of questions that I have because I have the microphone and then and then I thought it might be fun because you mentioned today over lunch or earlier in the that one of your desires when you wrote the emperor's new mind which deeply inspired me was that you'd get mail and letters from young people that got inspired into and into the line of work that that's you the to practice and you said you were a little bit dismayed that you've got a lot of letters but they were from mostly old men young people in the crowd and I thought I thought it'd be great to only take questions from young people about that but first we'll take one from a reason the old person although I'm a cosmologists Oh everyone seems young to me so you mentioned and I know that you you actually have the fortune to study under Paul Dirac and he was yes yes lectures you his breaking of chalk inspired you to daydream and that kind of reconnect later on yes here at the arthur c clarke center for human imagination we like to explore the connections between between the arts and sciences and and one event that we did last last month or two months ago now was with ray Armentrout who's a professor of literature and poet and won the Pulitzer Prize in 2010 she's a member of the Clark center advisory board as well and she and I had a great conversation and mm-hmm and she we debated whether or not there's this relationship between between science and the arts and it's often you know here we have classes and I'm sure there are such classes as you know physics for poets yes I grade and she and I co taught a class called poetry for physicists and that was really fun they make that class and explore the commonality but I remember mentioning in the first day of class that Dirac was famously anti poetry and he wouldn't even say things like in science you attempt to explain the most complicated things with the simplest of languages but with poetry it's the exact opposite using what similarities differences do you see between these two different cultures as they've been described well it's undoubtedly true that aesthetic judgments are important science well I would say important particularly either in mathematics or in very basic science you might have science complicated things which might not be obviously beautiful well biology things are obviously very beautiful but um I don't know certainly sir let's speak only for the fundamental basic sciences then it's ungodly true that there is a deep beauty and in the theory when you get it right but I think it's dangerous the arm to the other way because people have to do Argos you know my theory is so beautiful it has to be true Dirac himself said that yes well of course he was rather more a better luck if it's I don't think we should call it luck but he certainly had a fantastic reputation and getting it right well they're not quite always but he's very good and certainly with the electron there was some comment wasn't it that somebody asked him when you look at searching for the equation for the electron how did you come across the that that beautiful equation to us he said well I have a very keen sense of the beauty for a sense of the beautiful and when I found my equation I knew I was right so something like that of course it's probably could totally Epoque refer Mr curry that's right but he did certainly value the beauty of the mathematics I think it's undoubtedly true that if you get it right I mean the ideas of game gauge theories see it wasn't the idea I mentioned the Colusa Klein model but what really survived mainly was Herrmann vials ID there's a different way of thinking about how electromagnetism could be incorporated and he had the idea well with with Einstein's theory you can have a vector and move it around a loop and it points in a slightly different direction when you've moved it around the loop but his idea was if you have a little ruler or the length of the vector Keeler and you move that ruler around a loop in be a different scale and you get around and he showed that the equations Maxwell's equations could be incorporated Maxwell's electromagnetic equation incorporated in this idea and then Einstein said no no that doesn't work because proton trake it round the loop and it will be different from me listen listen and it'll disagree with quantum mechanics and things like that so so we well went away and said oh dear that's nothing I don't know what he said but then he and the number of other physicists came up with the idea okay when quantum mechanics became established you said wait about this phase and this phase is somehow an unobservable thing and you haven't really tell it go round the loop and it can get rotated around and that's the the phase idea and that's what we survived today but of course the name gauge theory which was because originally it was a gauge in the sense of how big it real and it's a bit of a misnomer because it's not really a gauge in that sense but gauge theory is the foundation of all of the physical interactions I would say except for gravity which is a bit different well some people say it's a gauge there's a different kind of theory but the gauge theories of all the other interactions can't come from home and vials beautiful idea and fantastic so a lot of times a famous physicist Richard Fineman said you know anybody who tells you they understand quantum mechanics is a sort of is a polygraph test what is it about quantum mechanics and cosmology to a certain degree as well that leads and lends itself to eyeballed speculation that kind of brings out sure you get your share of emails and now you get emails and postal mail from strangely enough it's usually relativity yeah I never understood that you've hardly ever get people complaining about quantum mechanics they complain about relativity all the time perhaps they don't understand it's enough to complain about but some no it's completely crazy you see that I have to blame a lot of the crazy theories people have now on quantum mechanics because this is a completely crazy theory but it works so beautifully well but um so yeah there is this thing about not understanding quantum mechanics and and he was boy has some things I forgot what it wasn't yeah if you if you want I think you understand quantum mechanics you haven't understood it I forget that one of course is experience experience this enough fun but um you should get two reasons and I think they're two quite different reasons and I in one of my books I said there are two different kinds of mysteries there the ex mysteries and the Zen masters over zeem is just as you prefer that the ex mysteries were those e mysteries are the ones that you can sleep peacefully with desserts you see of snoring or something they are the puzzle mysteries they are puzzles and for example the entanglements which are very mysterious things you can't particles can be very far separated and they still have share information and in a certain sense between them which cannot cannot be explained in a classical way so it's purely quantum mechanical is it entanglements and you can do experiments on this you seem to influence what the experiment does over there but not in the way that you can send a signal very strange and that's a puzzle mystery it's not inconsistent it's just this extremely puzzling but then there are the ex mysteries and those are the ones that Rio should be crossed off in the sense you see the paradox mysteries so that's the ex in paradox and these Schrodinger's cat is a paradox because it doesn't obey the Schrodinger equation and you see the cat is either dead or alive has gone through one door or the other door it's it's not in a superposition and so it's really a paradox with what we see the world no people have their ways of resolving it either you have to go into many worlds and then you have to go into them anyway you have to doesn't make sense in that you've got to explain the world we actually see not a whole host of things we don't see and that's one thing which doesn't explain it another thing which doesn't explain it which is the conventional quantum mechanical view is that somehow the system gets entanglement with the environment and then you say well you can't you don't know what the environments doing so you do a trick which is sort of tracing over it but it doesn't make sense if you look at this it's what I call a double ontology shift you have one ontological view you say well the wave function describes the world if you like and then you say you've got an average over these different things and then use melih description which is called density matrix and that allows you to do this every averaging this you shift from the wave function or the state vector to the density matrix and then you do a little rotation of the identity matrix which is perfectly legitimate within the world of density matrices and then you say you've diagonalizes you say these numbers down the diagonal represent probabilities and then you say what's the probability from States well that probability of different states is shifting back to the original ontology and you've gone through and then back again it's a complete cheat you haven't got a consistent way of representing the world continuously so you you have to make a jump and then a jump back so it's it's it doesn't doesn't really work so you've got to do something new there and that's not quite fair on there are models and there are other models in the world I've sort of hinted that here certainly which preceded the one I was talking about there's the browbone scheme the trouble one trouble with that it's it's rather a mess that's one trouble but one trouble with it is it doesn't claim to have different results from quantum mechanics it just has the better ontology I think it does have a better ontology but it doesn't really do anything for you there were these other schemes by Girardi and his collaborators which were much better in the sense that they were deviations from quantum mechanics which could in principle be detected which a classic theory someone were disproved but I mean the this it's a serious ass you can see it's that theory or is pure pure quantum mechanics still true do you have deviations from samskaara mechanics so the reason it doesn't reason it doesn't make sense is it's not a consistent theory it's not our fault it's the fault of the favorite yes I think I turn this so having touched upon deep space cosmology rocket science I thought we turn to something simple like brain surgery and neuroscience so like many of the audience members I'm guessing you arrived here tonight using trusting your life essentially to software to a computer that you probably near pocket or your car has on its dashboard a computer that guided you and you basically trusted it completely with your life and and certainly with being on time here tonight I usually turn off the actual voice commands when I'm driving with my wife so I don't have to women yelling at me but but I wonder you know as computers get more powerful as we build as we're already building the fundamental qubits in my laboratory in here at the UCSD and other groups around the world for quantum computers and I wonder you know that we hear about this logical progression where you know chess is very hard and and humans are very good at chess and then humans were beaten by computers at chess therefore you know computers are going to take over the world and software some day especially even in the absence of advanced hardware which we're developing here at UCSD at Cal IT - in other places how is it in your mind I mean do you really envision that the ultimate evolution of quantum mechanics will be to describe quantum computers as as brains or vice versa or similar in an attorney sense that could not be distinguished well you see the view I have is actually not easy people complain and they say well you're putting your same consciousness is a quantum process and the brain is a warm and messy and how do you get quantum mechanics well you see I'm saying something worse than that I'm saying it's not just quantum mechanics it's where quantum mechanics goes wrong see so we don't even know it goes wrong in this way because of experiments which have not yet achieved that level so I'm hoping that they will show that it goes wrong in the way it's claimed because the scheme that Stuart and I have developed in various ways depends on that scheme so I think there's good reason to believe that it does go wrong at that level but we need better than reason to believe we need experimental evidence that that's correct but this is as I say going beyond a quantum computer idea it's saying a beyond quantum computer so it's so it's more exotic now you see my position is that quantum see there's the different things here I'm saying that consciousness is something which is not a computer action it's not the inaction of an algorithm it's something beyond an algorithm which enables you to achieve things which pure algorithms don't achieve and we know that there are mathematically we there we know there are limitations that's absolutely established mathematics and these limitations are well understood but whether the brain does something different is another question and I believe you can make good arguments that it does do something different from your computation and if it's a quantum computer it doesn't do that you see quantum computers just do a computation they may do it faster there are certain types of computation that they should do faster it's a little bit limited at the moment once they seem to be able to do it's not really like a nor Denari computer we can program in all sorts of different ways and it does fantastic different kinds of things whereas a quantum computer it's just a very limited number of things that we know it do in principle better than or than a computer but maybe that's a limited temporary stage but it's still only doing computations faster or more bigger computations or something more powerful so there's not a qualitative difference than what they can do the claim is that if you could have a beyond quantum computer I think there's a name that the people have given to their that incorporated whatever it does whatever the world does when it reduces the state and that's what Stuart when my ideas suggest would have to be the case yeah that would be it could but you see it's it's it's it's not on the spectrum of what can be achieved you see people talk about 10 years 20 years even 30 or 40 years but this is something which we have no idea how you would do it present time yeah very good so I'd like to take maybe two questions from audience members under the age of seven no just kidding us maybe preferably a young man a young lady could ask a question that would be fantastic is there a volunteer in the back young man young man okay let me see none of my students qualify as young okay well we should start with the youngest possible are there any questions up in the front I see some very angelic young faces here here's one okay is your chance to interact with physics royalty hi thank you for speaking today this has been really interesting but I had a question about your cosmological theory concerning the eons and the inevitable big things so if I understand correctly what you're saying is that in our distant future there's going to be a big bang and then in that universe's distant future there will be one but if the rarity of a Big Bang exists then are you saying that it's a rarity that is inevitable or that the first Big Bang was just a very rare occurrence and that now it will no longer be a rare occurrence sorry I can tell you the what well I am Not sure that I caught exactly what the question was I'm sorry it's oh sorry yes first our first Big Bang when the scheme I have they gone indefinitely so there wasn't the first one it's a bit like the steady state model in that sense that the universe was already there I worried about this because I once Wheatley gave a talk in the Vatican and I was worried that this model would not be viewed with favor because the origin of the universe was supposed to have been as a certain stage but they took what I regard as the correct attitude from their perspective namely that the creation of the universe was the question of the entire thing all their boom and so not bang but boom let's suppose this whole thing was this infinite sequence of things yes but that's it doesn't have to be like that it could be something where there was a really beginning one and so how would one tell that I have no idea you need a good theory which which really pins it down much more than I'm able to at the moment so if the theory really demands that it does go on forever and that would be the way I view it then that would be it yes there is no original one it was there forever let me make sure this is on here you go thank you so my question on consciousness is that I in thinking about data and what we see and will contest and demonstrate on consciousness when we see for example not religious near-death experiences but they die on the table they go to another room they report things sometimes miles away in theory what would you say um could explain this they thinking about sort of ESP yes yes well I'm not not a fan of that idea apparently because what you see I mean who knows but I'm you I suppose the idea of some sort of quantum entanglement between states between brains and different rooms I don't know how you'd get that from one to the other that's the problem I mean you it's hard enough in a single brain to see how you can get the kind of entangled states that you need for this scheme you certainly need something which would cover a large areas of the brain so that the the quantum state if you like isn't just within a single neuron it would have to be extending across several maybe loads and loads of neurons altogether so there is some kind of not exactly EPR but that extrasensory perception is that is that a xposed extrasensory what's the Arsenal but anyway the thing is it's within one brain but if it's from one brain to another I really have no idea how you could conceivably get the entanglement established it's it's it's hard enough in a single brain to see how that's going to work so I just I just have I think it's a pretty long shot thank you I'm afraid so part of the reason I wanted young people only is so that they can I can get first dibs on their applications to come to UCSD thank you young people for your questions I'm sure there's many more I would like to thank Sir Roger Penrose for coming tonight thank the Penrose Institute we have our conference on consciousness going on at the Hyatt Aventine I believe there might be some tickets still available for that conference and thank you so much for coming and on behalf of the arthur c clarke center of human imagination we should be televising this event in a couple of weeks within a couple of weeks you'll be able to relive it again in a future universe thank you very much you

Channel: Arthur C. Clarke Center for Human Imagination

Views: 84,217

Rating: 4.8128896 out of 5

Keywords: Sir Roger Penrose, Roger Penrose, mathematics, physics, faith, quantum physics, Clarke Center, Arthur C. Clarke Center for Human Imagination, Arthur C. Clarke

Id: aaIdJMxP6bA

Length: 106min 13sec (6373 seconds)

Published: Fri Sep 01 2017