Neil Turok

0:09:07 Born in Johannesburg, South Africa, 1958; grew up in a very political family, always in trouble; police raids; parents very involved with African National Congress and the resistance movement; father [Ben Turok] went to prison when I was three for three and a half years, and mother when I was five for about six months; we left as refugees in 1966 and moved to Kenya, then Tanzania; had a wonderful childhood in Africa and then came to Britain; when mother was in prison I stayed with my grandmother in Durban; she was a Christian Scientist and took me to Sunday school which I loved; by the time I returned home after six months I was praying every night which my two elder brothers found ridiculous and broke me of the habit; used to have debates with them on the existence of God

4:09:15 Father trained as a land surveyor and had an engineering/mathematical leaning; he taught me Pythagoras’s theorem and how make maps; he interested me in the ancient Greeks as he was a keen student of philosophy; he was imprisoned in 1961`and while in prison he studied philosophy and took a degree by correspondence; most interested in the pre-Socratic philosophers, people who had suddenly seen the world with fresh eyes and had a perspective uncluttered by mythology; he was a strong influence on me; his passion for politics and freedom was inspiring; mother was the carer, left to look after three boys on her own when my father went to prison; very difficult because she was also a political activist and under constant harassment from the authorities; under house arrest some of the time; her own family effectively disowned her because she had married my father; tried to encourage her to leave him; she is a brave person and when my father finally got out of prison she helped him to escape across the border; she then got permission to leave with us on condition that we never returned and took us to Kenya where we met up with our father again; she was the backbone of the family and continued to play that role throughout our childhood; father always busy with a hundred schemes and ideas

8:36:17 First went to school in South Africa; I was very precocious and naughty, talked the whole time in class; moved up a year as I got quickly bored with what we were being taught; from the age of three attracted by physics - pouring, measuring and weighing things, loved geometry, fascinated with nature, collected insects, even hail in buckets to experiment with; moved to Kenya at seven and was in a school for six months in Nairobi; don't remember much about it but my father was in the ministry which made maps and remember seeing how they converted aerial photographs into topographical maps and I found that fascinating; in Tanzania I went to an ordinary Government school but had an exceptional teacher; she was a Scottish volunteer who had an identical twin sister who also taught, so did their mother; they all lived together in the school; she was my maths and science teacher, Margaret Carnie, and I am still in touch with her; she now lives in Edinburgh and is in her eighties, an absolutely exceptional person; as a teacher she taught me that I could do whatever I wanted; she gave me books, sent me outside to make a map of the school; I taught myself trigonometry, made measurements and scale drawings of the school; then she gave me books about physics; I learnt Archimedes principle, pulleys, weights, forces, and we did a lot of projects; she didn't instruct me but pointed me in the right direction; she was so convinced that I could do things that she gave me an incredible start; subsequent to that I moved to England aged ten and went to a primary school in Crouch End, London; my father was selling ‘Encyclopaedia Britannica’ as he couldn't get another job; at school they handed out pages of long multiplication, division, addition, and I thought it was a joke; I had done that four years before; once you have learnt the rules of how to multiply numbers you don't need to repeat examples but you use it for real problems; despite the fact that we had moved to England to go to better schools, I found the standard way below what I had had in Africa; however, secondary schools in England were much better; went to William Ellis, a grammar school in Highgate with some outstanding science teachers; bit of a shock moving from Africa to a grey London existence; had a wonderful maths teacher, modest but caring; I was a year ahead of my age group; was concentrating on biology, still collecting beetles, joined the British Entomological and Natural History Society, and elected a committee member of the society when I was thirteen; the amateur collectors whom I met were almost all over sixty but they were preserving the tradition of the animal collectors and classifiers; still believe there is more beauty in a beetle than all of human works of art

19:16:23 Came to Cambridge to do mathematical biology, but after six months, having taken courses in theoretical physics it grabbed my attention as the most powerful, simple, effective part of science that we know of; you can write an equation in one line that will describe a million phenomena with incredible precision and there is nothing like that in biology; I switched over to physics as an undergraduate; [AM asks for an explanation of Dirac's equation] Dirac working like everyone else on the basis of knowledge that had previously been discovered; he knew about relativity, about Schrödinger and Schrödinger's equation; he knew these things were correct because they had already proven themselves; Dirac wanted an equation which satisfied both relativity and quantum theory as described by Schrödinger; he thus had a mathematical puzzle and there is only one equation that satisfies the terms; he was the lucky guy to be in the right place at the right time with the right mathematical tools; he had an extraordinary mathematical mind; he had very little formal training having been trained as an engineer; never liked mathematics for its own sake; just invented it as he went along; his equation now describes ninety of all the particles that we know of, and the remaining thirty are described by Maxwell and successor theories

22:57:10 Coming to Cambridge found the course completely unsystematic; the first lecture course we took was called modern physics and we were lectured by Tony Hewish; it involved hand-waving (Hewish), quantum theory, radio astronomy, a little bit of relativity, a little bit about data and how you make sense of it; no mathematical derivation in the course was over two or three lines but it gave you a glimpse of a lot of exciting science and ideas which was deeply influential; think it was a model of its time as mostly when physics is taught in universities now, and certainly in the U.S., it is taught in a very systematic way where it takes you at least two years before you get to anything modern, which I think is a big mistake because you want to grab people as early as possible; once they are motivated they will learn much faster; thus without that course I might not have gone into physics at all

24:49:11 Although I had done very well at Cambridge I was tired of it; there were things about it that I didn't like; it is an elitist institution although I'm not against intellectual elitism in the best sense, but a lot of the elitism here ends up with having formal dinners where students from middle or lower-middle class backgrounds end up wanting to pretend they are almost aristocrats; becomes almost farcical; [later] was at Downing College, a science college, which I liked, but didn't like to see the students getting increasingly interested in putting on airs and graces, which I didn't fit in with; decided not to stay here to do Part 3 mathematics and went to Imperial College and took their masters in theoretical physics and then a PhD; difficult as life in London is nowhere near as nice for a student as Cambridge; quite a lonely time; tiny student digs; all the students go home in the evening so no real college life, plus working on a PhD which in theoretical physics mostly consists in banging your head against the wall and you have no idea whether you have any talent or whether the problem you a working on makes any sense; I spent two years like that without a clear idea of what I was doing; I worked extremely hard in my first year on a problem I then realized was not an interesting problem; you learn through this but it is not an easy route; I would advise anybody who is learning theoretical physics to be very careful that you are really willing to put up with some very hard times; it is not a subject where you get a quick reward

28:37:00 Father worked for the Open University and was very committed to his work; I used to see them regularly; they lived in Watford; while I was in Cambridge they moved to Zambia so were not around for long periods; when a graduate student I was lucky enough to find a mistake in a paper by a very famous scientist who later won the Nobel Prize, Frank Wilczek; he came to England for a conference and I saw him and he graciously accepted and withdrew the paper; I wrote a paper with my advisor on that problem and then I got a post-doc. at the Institute of Theoretical Physics in Santa Barbara which is probably the leading such institute in the world; fantastic place; interdisciplinary; think they had three permanent faculty when I was there and about twenty-five post-docs. so we didn't interact with faculty very much; they had set the tone and the quality but it was left to us to find other post-docs. to work with; as a result I worked in many different fields and looked around to find a niche for myself; there are very few places like that today and even that institute now has a faculty of 10-12 and far fewer post-docs; it was a new institute with a freewheeling atmosphere; every single one of the post-docs. that I was with now has an excellent position in theoretical physics yet there was not planned mentoring or supervision

32:02:10 I lost contact with the teacher (Margaret C) in Tanzania and then I came to Cambridge in 1997, and a couple of years after I did some work with Stephen Hawking and I was on a TV documentary programme which she saw; she wrote me a letter; delighted; went to see her in Edinburgh and she was the same person she always was; have stayed in touch with her since; when I saw her I started to tell her what I worked on; she stopped me and said this was not what interested her; she wanted to know what banged in the big bang; a good question that coincidentally I was working on and have subsequently given as a title to talks and attributed it to her; indeed it is the most important question

34:59:16 [TK Having read 'The Endless Universe' explain what the cyclic model of the universe is all about] The original motivation for the cyclic hypothesis came from string theory and a development of it called M-theory; these are our best current attempts to unify all the laws of physics into a single mathematical framework which is consistent both mathematically, logically and also consistent with everything we know about the world; lot of progress has been made and it does seem to be a single mathematical framework in which all the laws of physics fit - Einstein's theory of gravity, Maxwell's theory of electro-magnetism, Dirac's theory of particles; all these fit together in a single framework now called M-theory; other people had developed this but to me the application of M-theory and the true test of it would be to see whether it would describe cosmology, could it describe the universe; the origin of the cyclic picture goes back to a workshop in 1999 where we invited the leading researchers working on M-theory and leading cosmologists just to see whether anything interesting came out; this was at the Isaac Newton Institute in Cambridge; we had several lectures and during one Paul Steinhardt, my long-time collaborator from Princeton, and I both had the same idea that within M-theory there are these objects called branes (shorthand for membranes) but you can have a one-dimensional brane which is a string, a two-dimensional brane which is the membrane or surface, a three-dimensional brane which is space, or four-dimensional branes and up to ten-dimensional branes which can exist; the world, if we want to picture it in that way, consists of a ten-dimensional brane with other branes of lower dimension imbedded inside it; the intriguing thing is that you can't do this in an arbitrary way; once you have decided you want a theory of ten-dimensions you have to have all the other branes of different dimensions within it, and the rules whereby they interact are unique so there is no adjustment possible in the theory, which makes it attractive

38:33:12 Up until our workshop nobody had seriously tried to apply this to cosmology; at our workshop we were fascinated with the particular picture that had emerged, that the way to get from ten-dimensional M-theory to the real world was to get rid of seven of the dimensions by curling six of them up in a little ball so at every point of this room you should imagine that with a really powerful microscope I could look very closely at each point of space and would actually see an extra little ball of six-dimensions; so every point of three-dimensions would have six curled up; even though it at first sounds shocking it is a very beautiful idea when you look at it more closely; most intriguing to us was that there was a seventh-dimension which was even more bizarre; the seventh-dimension is a gap between two objects which are three-dimensional branes; so you have a picture of the world with the three-dimensional brane we live in, and the particles we are made of travel around in this brane; light travels in this brane, but just next door to it there is another brane; these two branes are called 'end of the world' branes meaning that they are the end of the seventh-dimension and there is nothing beyond them, they are almost like mirrors; the world is a sandwich with nothing outside it with the seventh-dimension of space in between the two three-dimensional branes we live in; at every point of those three-dimensional branes there are another six-dimensions curled up; our thought was what happens when these two three-dimensional branes collide? Must be a pretty violent event as the whole dimension disappears for a moment; on the other hand the three-dimensional brane we live on does not shrink to a point when they collide, they simply move together; therefore it can't be like the big bang because as we knew that was an event where all of space was at a point; we could see immediately that here was another possibility for a bang which is that the space we live in did not shrink to a point, all that happened was a collision between another world and ours

41:51:12 Subsequently we worked through the mathematics of this and discovered that this event of the brane collisions indeed appears, if you try to describe the set up using Einstein's theory of gravity, just like the big bang; in Einstein's theory there is not a complete description of these branes colliding and when you add that element in you find that indeed space does not shrink to a point at the back, space is extended; now you have the possibility of a physical mechanism which caused the big bang which is describable; if the whole universe came out of a point that would not be mathematically describable; we do not know how to describe the structure of a single point; what we use in physics are differential equations with different points, and can't write such an equation with one point; if you had a picture of the big bang that was an extended bang across space, now you have the possibility of describing a physical mechanism that caused the bang; that is where the cyclic picture emerged in trying to understand how to describe the big bang's singularity; what we realized was that it could be the collision between two of these branes and that meant there was time before the big bang; but if these branes can collide once then they can collide again; quite quickly after we had invented the initial model called the ekpyrotic model (ekpyrotic means out of fire taken from the Ancient Greeks picture that the universe began in a conflagration); when we realize it could happen many times and indefinitely we called it the cyclic model

44:23:10 [TK: You say three-dimensions expand constantly and the only thing that shrinks is that spring-like force between the branes in the fourth-dimension] Exactly, it is essentially like a pump [TK: this gap is really small - 10 to -30 metres - is it possible to imagine where it is?] It is everywhere so every point of our three dimensional world is just 10 to -30 metres away from a corresponding point in the neighbouring world which is, if you like, the mirror world, sitting at the other end of the seventh-dimension; we are only just separated from it by an absolutely immeasurably small distance; it is interesting to ask whether there are any other manifestations of this extra dimension; in fact the origin of the seventh-dimension was that in our world there is a peculiar asymmetry in nature - left-handed objects are not the same as right-handed; when you have neutrinos (certain kinds of elementary particles) they only come left-handed; anti-neutrinos are right-handed; it has always been a puzzle why nature is asymmetrical; the reason why this two brane picture was invented is precisely so that the left-handed guys can be on our brane and the right-handed on the other brane, then mathematically it all works out

47:08:07 [TK: You said that atoms and light exist in one brane] In the other brane there is other stuff [TK: The force of gravity connects them?] Exactly [TK: What does that look like? You mention the dark matter might be the gravity of the other brane] The dark matter might be the matter on the other brane and the matter on the two branes interacts only through gravity; the way we understand gravity is that it is the curving of space, which is what Einstein understood; the sun bends space and that's what keeps the planets going around in circles around it; in this M-theory picture its really what I call Einstein++ because it says there are not merely three dimensions but ten; then there are all these other objects of different dimension but each of them behaves exactly in the manner that Einstein envisaged; you have the two branes and matter in one deforms the space in between the branes and that is how gravity is transmitted across the gap to the other; that is how the dark matter influences us; this is a neat picture as it does predict dark matter which is visible only through gravity; that is what we see when observing a galaxy; light only moves on our brane; the unfortunate thing about this picture if true is that it is really hard to test; since our only way of interacting with the dark matter is through gravity we can't make dark matter in a laboratory; it is way beyond the energies we can get in current laboratories; its an unpleasant situation that you have a marvellous theory but you don't yet know how to test it; I believe that it is all the more reason that we should focus on the big bang because we know it happened and can measure the outcome in many ways, and can use that to check whether this theory is right

50:14:24 [TK: How can you check? You mention gravitational waves in your book..] Yes, there is surprisingly a remarkably direct way of checking this picture that the big bang was a brane collision with gravitational waves; these are ripples in space which travel at the speed of light; we have never detected them directly because they interact very weakly with matter; even though we believe the universe is full of them we have not been able to measure them yet; they will be measured within the next ten years; when they are this will be a new window on the universe because we will see black holes colliding and all kinds of violent phenomena which emit gravitational waves; because these interact so weakly with matter it is a wonderful thing from the point of view of seeing the big bang because it is just like the universe is transparent to gravitational waves; so when we look out at the sky now we see the microwave radiation from the big bang and that shows us the universe as it was 13.7 billion years ago at about 300,000 years after the big bang because only then had the universe become transparent to light; before that time it was very dense and hot which is opaque to light; using light we can never look back earlier but gravitational waves take us right back to the bang itself; the waves emitted at the bang would just travel straight through the plasma without any interference and straight into our detectors; there are experiments being planned - LISA a set of three satellites which will be put in space in 2013 or so and they will be looking for gravitational waves coming out of the early universe; the way in which you check this theory of the brane collisions is first of all by a negative check; the standard picture of the big bang just accepts that the universe emerged from a point without any explanation; what state would it have had to be in order to end up like it is today? The answer to that question is initially very puzzling as here is a tiny universe springing into existence and how did it get so big and smooth and uniform in all directions as we see it today? That was just seen as a paradox for a long time; puzzles led to a standard picture in cosmology according to which you simply assume a universe jumped into existence, and you assume it was full of inflationary energy which has the property of making space expand exponentially; you can add this energy into Einstein's theory of gravity and it is a repulsive form of energy which blows the universe up and makes it very smooth and uniform; but it is never really explained why the universe started out in this way; to come to gravitational waves, this epoch of inflation has a very dramatic side effect; when you make the universe blow up exponentially it is such a violent process that you generate lots of waves, the ripples in space time which are just there present in the vacuum, even in empty space; when you start to blow up exponentially this enormous blow up spews out gravitational waves which we should be able to measure; the cyclic model is much gentler; you have these two objects which drift together over periods of billions or even trillions of years before they collide; when they do so all of space is not at a point, it is all spread out; when they collide they simply fill all space with radiation and then it subsequently expands; you do not get the gravitational waves that you would with inflation; if these gravitational waves are seen they will instantly disprove our model so it is testable; even though direct gravitational waves will not be detectable until after 2013, next year something called the Planck satellite will fly and that will have the means of detecting gravitational waves indirectly though their effect on micro-radiation coming from the early universe; Stephen Hawking bet me when we first came up with our model that gravitational waves will be detected by the Planck and our model will be proved wrong; I accepted the bet which he has not yet set; he plans to go into space three or four years from now on Virgin Galactic; I have suggested that, if I am right, I go into space, but he did not accept; it could be that next year our model may be dead; I have worked on theories before that have been proven wrong; I think it is good science and one should be humble in the face of the universe; the best we can do is make the best, most consistent models that we can, and then we have to test them ruthlessly in order to prove them wrong; that is progress as it rules out that avenue

Second part

0:09:07 [TK: What is dark matter and what role does it play in the cyclic model?] Dark energy is nothing but the tension of these branes; when Einstein first developed the theory of general relativity he realized that space could have tension and he called it the cosmological constant; reason it was cosmological is that the tension has a very peculiar effect when combined with gravity; normally used to thinking of the tension as causing something to shrink but if you put the tension into Einstein's equations it does the opposite and causes the world to expand; Einstein used this to make a static universe model; he assumed the world was a three-dimensional sphere and then the gravity of ordinary matter would make it tend to collapse, and balanced tension and gravity against each other to make a static universe; unfortunately it was unstable and his model didn't make much sense so he abandoned it; ten years later it was found that the universe is expanding and he should have predicted that; though he abandoned the cosmological constant we always knew it could be there and the surprise has always been why it is not bigger than it is, why is the tension of space not huge; even if you have space with no tension and start adding particles and fields to the universe each one of those particles contributes something to the tension; to end up with very small tension is really difficult; in the late 1990's quite strong evidence emerged that the tension is not zero but actually positive and that we call the dark energy; so it appears that apparently empty space is actually full of energy and energy associated with the tension of three-dimensional space; the surprise is why is it so tiny at 10 to the power -120; though ridiculously tiny nevertheless it matters in the universe today otherwise we would not have seen it; very important for the future of the universe as it causes it to expand faster; we are currently 13.7 billion years old and at another 13.7 billion years in the future this stuff will have really taken hold and begun to dilute away the galaxies exponentially; further billions of years on almost all the galaxies we know now will have disappeared from view and we will be alone in an empty universe surrounded perhaps by our nearest neighbour galaxies but nothing else; people in the future will be very puzzled by the apparently empty universe; they won't see the radiation left over from the big bang because it will have been diluted away; faced with a universe which started from a big bang which ended up dominated by dark energy we thought we would try to see things from a different point of view and that is how the cyclic model arose; we had this picture that the bang could be a collision between branes, that the branes would separate and possibly they would collide again; with regard to dark energy we discovered that when the branes separate if they do have some dark energy that causes them to expand and become very flat and parallel with each other; the dark energy can actually decay and can be the force that brings the branes together to produce another big bang; the dark energy makes the universe empty, smooth, vacuous and ready for another big bang which will produce another universe which is very big and smooth and will be emptied out again by the dark energy; so the dark energy is like a stabilizer; without it the branes would collide and the wrinkles and deformations they had acquired in one cycle of evolution would be magnified the next time and the whole universe would become more contorted and violent; without dark energy our model does not work whereas in the conventional picture of cosmology it is not necessary; on the puzzle of why is it so small? People working in the conventional framework have given up saying we can never explain why, at the big bang, whatever produced the bang somehow made the choice to fill the universe with radiation, matter, huge densities and energies and then add in 10 to the -120 of dark energy; instead they resort to the anthropic principle which says that maybe all kinds of universes emerge but we are not there in most of them so that if the dark energy was much greater in magnitude then it would have killed us; an appealing argument in some ways but does not have any predictive power; in our case if you have a picture of a very old universe, much older than 13.7 billion years, in previous epochs the dark energy played a huge and even controlling influence, then you have a huge amount of time for this dark energy to relax and its values can change; in theories like M-theory everything can change and all the laws of physics are dynamic; maybe what has happened is that dark energy has settled down to a value which is just right to keep the universe cycling in a stable fashion; given that the universe is able to have long cycles its entirely conceivable that dark energy has settled; we have published some papers on this idea and it is a radical alternative to the standard view; what we have shown is that technically we can construct mechanisms to make a model which will self-adjust the cosmological constant to the small values like the ones we see today; its only a model and not clearly true but the dark energy has made us really rethink our concept of cosmology and the big bang whereas people had seen it as a one-off intervention

12:20:09 [TK: You also write that no form of energy in the past ever goes out of existence and when cosmologists study dark energy today they are also studying the same type of energy that dominated in the distant past and will dominate in the far future. Could there be any information stored in the dark energy about the past and the future?] Yes, definitely; in the cyclic model as the universe passes through one of these violent events it happens that any signals or radio waves left over from the previous cycle are preserved; you will need very sensitive detectors to read it but its there in principle; it is an exciting thought that we could possibly communicate our discoveries about science to future generations in future cycles; what actually happens near one of these events is that all the particles we are made of lose their mass as the branes collide and move at the speed of light ; it would be a very unfamiliar world where we would be blown apart in a burst of radiation and immediately after be reconstituted into material objects

14:34:08 [TK: Is the big crunch just another name for the big bang?]

Yes. [TK: Maybe something more about extra dimensions] According to our current understanding of the laws of fundamental physics and unified theories, the laws of physics we see are largely determined by the size and shape of the extra dimensions; so at every point in this room there are another six-dimensions of space curled up in a rather complicated little ball which we can study mathematically; the detailed configurations of the extra dimensions actually fixes the physical laws we see - electro-magnetism, the strong force, the weak force, the different spectrum of particles; at one level we have not solved these problems in physics but converted it to another problem which is - Why are the extra dimensions the way they are? But that is progress as you have taken an apparently insoluble problem and converted it into another which may or may not be solvable; from my point of view what makes it interesting is that we have learnt from this framework that not only do the laws of physics govern the universe but the universe governs the laws; if we understand cosmology then we understand the laws of physics; this structure was determined at the big bang so when the bang happens you should not only study the gap between the branes which causes them to collide, but the other six-dimensions are doing something in this process at the same time and it better be mathematically consistent; maybe in involves changes in their configuration and once we have understood the whole process in the big bang maybe we will understand why the whole universe emerged; then you will have understood all of physics; the one question will be what banged

18:01:24 [TK: Do you think the universe is a cosmos that can be explained rather than a chaos that cannot?] I don't know if there are limits to knowledge; some people in the last years have become rather pessimistic and have resorted to the anthropic principle and similar arguments to say that this is the end of the road for physics; I know that if we take this attitude we will get nowhere [TK: But you say that this is the best time to be a cosmologist, why?] Because the last ten years have seen unimaginable amounts of data collected from the universe; I was a cosmologist in 1992, before the Kobe satellite mapped the universe for the first time, when I was seriously considering giving up because most of the discussion was based on prejudice as there was no good data; 1992 suddenly gave us a clean picture of the big bang and for last ten years we have had a stream of high quality data and we now have the prospect of measurements of gravitational waves looking right back to the bang; it is an unique period in human history; not only are we speculating on the origin of the world but we have the data to test these theories; I think to be pessimistic now is really ridiculous

20:41:15 [TK: Are there any ethical problems connected with the cyclic model?] I shall give you an example of an ethical problem which is that according to the cyclic model the basic motivation is to try to understand what happened at the bang and to make mathematical models; our first statement is that it is interesting to try to make a consistent mathematical model of the big bang itself; some people don't want to even consider this saying it is beyond science, religious territory; it is an ethical statement in my view to say a subject like this is legitimate science; not only can we do mathematics but experimental test observations, and we should; I think it leads to a better appreciation of the universe; even if you have got a model that is wrong you are trying to understand the universe; some people are arguing even within physics that we have reached the end of the road and that there are some problems too hard for us to understand; I think it is our ethical responsibility to keep going and to encourage young people who may have better ideas than we do; for me it is a very deep belief that even if science is going to be much more difficult from now on it is something that we have to do and our children will never forgive us for giving up; what we have learnt from physics is that nature is remarkably simple once you see through all the details and it is one of the treasures of humanity that we have this picture; interest in pure science and honest thinking about the universe is an activity which is common to all of humanity, should be cultivated and worked on, and if the next leap takes 10,000 years, fine, we will wait

26:12:10 [TK: If the cyclic model proves to be right would it be possible to abuse that knowledge in some way?] Very likely, all knowledge can be abused and it is up to people to use it wisely; I don't think there are any intrinsic ethics in science but they have to be added; having said that, I am not worried by any applications at the moment as its very far in the future that people may be able to manipulate these energies; at the moment laboratory energies we can reach are about 10 to the power of 15 times too small to probe any of the physics of the bang itself; I think probably our descendants will figure out how to do it one day but I'm not too worried about it

27:59:14 Probably the single greatest breakthrough of the last ten years has been the realization that gravity is describable in a way without using gravity; gravity is the curving of space according to Einstein, but in the late 1990's a young Argentinean physicist called Juan Maldacena made an exciting conjecture for which now there is a huge amount of evidence; the conjecture was that in certain situations you can take a chunk of space which is dynamical but bounded and that you could describe everything that happened in the interior purely by what was on the boundary; called a holographic principle and has been used to explain black holes, for example; in the last few months we have been using this to understand cosmology so what we do it to map a dynamical universe called a bulk onto a boundary and we follow the system as it goes towards a big bang, a singularity; what we have shown is that on the boundary you can describe how the system goes through; essentially you take the bulk which has gravity in it, map it onto the rigid boundary, follow it until it hits a singularity, follow it through the singularity, come out on the other side and map it back into the bulk where it is again described by gravity; we have constructed the first complete model of passage through a singularity and it appears that not only can the world go though a singularity and survive but also in the process of heading towards the singularity it turns out that the variations in the density of the stuff on the boundary are created; these variations in density are of exactly the form we need to explain variations in density in the real universe called scale invariance; scale invariance is also a reflection of an underlying symmetry; what happened is that Maldacena's picture whereby gravity maps the matter on the boundary, that picture is automatically scale-invariant; we have written a couple of papers about this though there are many aspects still to be completed; if this picture turns out to be correct it will easily be the most elegant explanation of the origin of the density variations as it really all comes from symmetry principles

33:58:02 Martin Rees and Stephen Hawking are polar opposites; Martin's great strength is keeping abreast of the latest observational discoveries and facts about the universe and trying to piece them together in a coherent picture; think his contributions to cosmology have been on the phenomenological side; Stephen's contributions have been the opposite, in fundamental theory; from his point of view mathematical consistency and elegance is primary; its in the tradition of Einstein who wasn't too worried about data; Stephen's work has always tried to employ the most advanced mathematical techniques to address theoretical puzzles and problems so he would be much more interested in a fundamental theoretical paradox than he would in the very latest observations, although he has huge respect for them and should they become definitive he might even believe them; there is also a cultural difference between astro-physicists and theoretical physicists and the former are often quick to jump on a new measurement, star or galaxy, whereas the latter take a longer-term view; neither necessarily right and Martin and Stephen represent those two cultures

37:25:12 Cambridge has been fantastic for me mainly for two reasons, one was the amazing collegiate atmosphere; I was working in Princeton before I came here, an excellent department, possibly the best physics department in the world, but much more aggressive and self-promoting; what is so enjoyable here is that colleagues are very willing to spend time to discuss, share ideas or knowledge, without any agenda; the second thing that is great about Cambridge is the flexibility of the institution, that providing you fulfil a certain number of basic duties which are pretty modest compared with other universities, you can do what you want; coming to Cambridge I had the freedom to set up an institute in Cape Town, to raise money for it and bring in all sorts of allies and partners; I don't believe there is any other university in the world where I would have had that freedom; Cambridge provides an open space which is not too controlled which is very valuable; I was at Downing College for three years when I returned but have resigned; I think the college concept is in severe need of renewal and is no longer a community of scholars; too established, less ambitious and too many dinners

40:59:14 When my daughter was five I wanted to take her to Cape Town to spend some time with her grandparents; Herbert Huppert as chairman of the faculty board allowed me to take a sabbatical there to talk about possible collaboration with the University of Cape Town; my daughter went to school there and I was working on the ekpyrotic universe in peace; went to the university in order to fulfil the requirement to establish a link with Cambridge and asked what I could do; they said they needed maths as South Africa and had a strategic problem as they didn't have enough students coming through with high-level maths skills; idea emerged to set up a centre in South Africa for good maths students from throughout Africa and bring the best international lecturers in the world and create some mathematical stars; told my father and next day there was a rugby match on TV and I said I would come to his house to see it with him which he agreed to, with the proviso that I spend an hour in his office and produce a page on the proposed African Institute of Mathematical Sciences; next thing I knew was that he had faxed it to all the people he knew in higher education in South Africa and then I had to do it; when I came back to Cambridge he called me with news of a fantastic building for sale in Muizenberg, an 80 room hotel near the beach and told me to buy it; we did buy it for £65,000 using an inheritance that my brothers and I had; I brought the three deans of science from the local universities to the hotel and told them that this was where we were going to set up the best maths institute in Africa; one of the deans got very excited and he is now the director of the institute; we converted the hotel and through a lot of work and good luck it has become the most amazing institute

46:49:00 [TK: How is it doing now?] AIMS is in its fifth year and we've graduated about 160 students so far; they come from everywhere in Africa and currently there are 53 students from twenty countries, including 20 women; we designed it to be innovative with programme geared towards problem solving and encouraging people to think for themselves; the students have been incredibly successful and last year we had about 48 graduates of which 45 are now on masters and PhD programmes in top institutions, one is a lecturer, one is doing and MBA and another is working in an IT company; these students are the most highly motivated I have ever come across and given nine months at AIMS which they use to the maximum, they work 16 hours a day, learn computing and modelling, learn how to write and give presentations; through necessity we stumbled on a model of education which is extremely effective, getting people from many different backgrounds but all intelligent; the best teachers in the world are all willing to come to teach the best students in Africa; they all live in this hotel so it is a 24 hour learning environment with impromptu discussions and tutorial at any time so a terrifically intense atmosphere; after nine months these students are ready to go into any field of science; in an old institution like Cambridge it develops layers of bureaucracy, rules and curricula which are almost fixed in stone, whereas a new institution can jump to the cutting edge; at AIMS there is almost total freedom to create able people who can go into any technical field and contribute to it; doing it in Africa means that you get students with very high motivation levels as this is the chance of a lifetime for them; you might have thought Africa was the last place to develop a model for post-graduate education, in fact it has been the best place to do it; experience of a student from the Congo; my conception of AIMS went from it being a necessary step in solving a strategic problem, the lack of highly skilled people in Africa, more towards the conception that this will benefit science in the long run; believe that these people from different cultures bring a new energy and freshness into science, and very likely some new ways of looking at things; this year we have five students from AIMS in the maths department [in Cambridge] and previously you would almost never see a black African there, and the ones you saw were very isolated and felt second-rate; these students are having a fantastic time and I am hopeful that one of them will come at or near the top in the financial maths course here, a very brilliant student; it is now our culture at AIMS that we are going to prove something to the world that black Africans are every bit as good as whites at science; ridiculous statement by Jim Watson after which his genome was sequenced and found to be 16% black African used to encourage students; our dream is that the next Einstein will be an African

55:51:16 [TK: Winning the TAD prize means winning $100,000 but more importantly you are granted a wish. Can you tell us what your wish will be?] The wish has two parts and the first is that the next Einstein will be an African and that may sound surprising, but Einstein was a Jew and Jews didn't get into science until c1880 and were actually prohibited from going into universities in many countries in Europe; some Jews went into medicine but very few went into hard science; once they got into it they flourished so that over a quarter of Nobel prizes in physics were won by Jews and a quarter of Fields medallists similarly; I do not believe that this is something innate to Jews though some element of Jewish culture may be helpful - great respect for the written word, for study - but more importantly, they were out to prove something; the Jews were suppressed and persecuted but when they got half a chance they wanted to prove something about themselves; look at Africa, culturally one of the richest continents - music, art, design - and ingenious mechanics; there are geniuses all over Africa; anecdote from when teaching in Lesotho; second part of the dream is a plan which is to replicate AIMS all over Africa; looking for major donors - Bob Geldof may do so - and at TED this is what I will be asking for; looking for three donors to give $50,000,000 each to set up an endowment fund for student scholarships; we have the support of the African Union who have commissioned us to prepare this plan; we have sites in Nigeria, Ghana, Uganda, Sudan, Madagascar which we have visited and have business plans; when it is done we will have a network of AIMS and will be producing 50 graduates a year from fifteen centres in five years; we think these graduates could have a major impact in African development.