Are strings the theory of everything? (contd.)

0:00 Whatever the problems with not getting the problems of statistical models like this, at that stage there is a general good count and I'd like to talk about some of the things that people do not do because some of them are used nowadays and some of them reappeared via some of these alleys back into where they are at the moment. So in terms of this sort of naive diagram, we hit a war with experimental history that had common dual string frequencies. Whatever its advantages or disadvantages, it just couldn't be sustained. And so after that there's a general period in which bounded strings By and large, they're out of fashion. And if I were to say how would I characterize this into data, it's just in terms of publication. These are in hundreds. From about some 68 to 72, the publications on student literature have been picked up again, probably from about 84, thinking about this lull in the middle. And this lull in the middle doesn't necessarily have all that much to do with the...

2:30 The expected probability of the ideas in advance has rather more to do with the fact that postgraduates are on three-year contracts, so you have to make yourself as physical as possible. The most damaging thing you can do is to keep yourself from falling starved. And so that means that the number of the way in which you are cut off in a particular model makes you a lot sleepier. There are two very different types of activity followed on from this. The first is what you would say would be the orthodox response. That strings may be shown to be wrong because they were too soft. The first tactic is to try to put some gritty to them. In this period between the original strings and their revival, one tactic, so I'd like to comment a little on first, is really a question of grid. Because hadrons were grainy, string phenomenology hadn't even begun. So the one tactic is to try to make string things that have local gritty pieces associated with them. So we are no longer... Talking about theories, we're talking about models, which we haven't tried to preserve the best features of chronology that have worked so successfully, or are so successfully, but took into account the fact that the local objects, the points, were really there, and so this is going to be based...

5:00 I'm based on local, based on local as the elementary string, but it became apparent that it's not difficult to get stringy things, or at least to get stringy things to coexist with each other, and although this is a digression from the main thread of argument that we use at the moment, being used at the moment in the context of the university, I can give you a very simple... I'm going to show you a model of a Heisenberg co-magnet in which I either have spins going up or I have spins going down in a row and it costs me a certain amount of energy to put two adjacent spins up the paladin. It costs me a certain amount of energy to create states in my system like this. If I do have a configuration in which somewhere in the middle here I have just one pair, it's going to cost me an infinite amount of energy to try to turn this infinite sequence because I've got a semi-influenced... So although this is one of the ground shapes, it is stable to try to change it. Now, having said that,

7:30 The relevance is that field pillars of local fields are often continuously paramagnetic. If I have a classical potential, something like this, where my field might be there or there, then if this is my field, I'm only in one special potential. Then if this is a plus one, this is a minus one. Then, my grand state is either that my field takes a value of plus one or it takes a value of minus one. Well, it's not difficult to find classical configuration, so to flip, rather than like this. If I were to look at the energy density associated with it, so that I, although I have field theory, when I quantize it, it's going to have point particles associated with it, but I've also got blocks. So a lot of the theories that I thought I knew and I thought I knew what the part was associated with were actually an additional part that weren't present. Now, the answer might be to say, what? But this is just the type of effect that you get in the, in the, in the very background. Rather than just have local blips, you're used to the idea of a vorticity outside of which I have a superconductor and inside of which I have a normal conductor. And so it's perfectly possible to have stringy things coexisting, arising in your field.

10:00 There was a certain amount of work that said that a model like this, or not exactly like this, but models of flux tubes, we never really meant that a proton, that a pion, that was an approximation, we've been trying to elevate it to a billion. It was really a model and it was a broad brush model of what, if you looked at much more closely, really influenced you, and yet it was goofy enough, and of course had the monopole that they would tie up these flux lines, and if you banged one flux line, they would come off quite widely, quite angrily. So that was cool. As soon as you had done that, you opened up a whole new game. Because we're now looking at classical solutions to non-trivial theories, all the non-trivial theories that the unifiers were doing in the third column here, and that in itself meant that it's not about just looking at the string theory, and at that stage it became apparent that there's one monopole anywhere, and the whole of it is...

12:30 And there was one group of theorists who were drifting towards talking about the early universe. And then it dawned upon people that these strings that had been so carefully constructed were not ions at all, but were galaxies, or rather not galaxies, but the entities around which galaxies can see, because there is a problem of galactic formation, and we then moved into cosmic string. These are still an active branch of the interplay between quantum and the second, or whatever we're talking about in this little crowd here, where we now have two types of string, but we're still talking about pylons, or not pylons, but some of them in some states, we've got galaxies, we've got any string, but whatever we have, we're not talking about a theory of string.

15:00 We're talking about the novel effects of thinking that we want to do over time. So that is the one type of activity that you would expect. That the original string table, you try to patch it up, you borrow all the ideas from the increasingly sophisticated local field theory, and you then find yourself talking about cosmic strings. And I know it's an overused phrase, but... Which is a prime example of this kind of other space, at least in this case, although it's not done in times like Vancouver and the United States yet, but, and I think perhaps that comes with the last section, because that was the one way which a theory runs into the ground, the original theory runs into the ground. And so on and so forth. In the first instance, it was well worth pursuing that although you lost your body, you still drifted through the equation, because people who had dabbled in strings or played seriously with strings were very impressed by what was going on with local field theory, but in some ways they were a rather thin ball in terms of the underlying symmetry of the structure and algebraic structures.

17:30 And so they were still a significant body of people who, even though strings were nothing to do with mathematics, might have been intended to be a bit of anything or whatever. And this is the little pipeline running along here, on the dual stream, for people who are going to follow the equation, come what may. The strings that were being looked at so far, they weren't simple strings, they had two ends, and these ends were where the flavor was supposed to reside, so that when you had a string, the worst that could happen as it moved along was that it split, but the flavor that was carried by these ends, when you split a string, you create an end at the end. And that was why the string people were going yahoo to the cork people, because here in the original version, the corks had been depressed from having to do with geometry and cohomology. They weren't. They weren't. It wasn't surprising that the string had to end. Or more complicated strings, there are more complicated things involved. So, the problem was that these strings were only used, hopefully, for particles that were very close in distance. Now, people have dabbled with how you would have, bear in mind, that a statistician would have p-strings, not p-strings, and that didn't really work. It was apparent that you could put in fermionic degrees of freedom into string languages with some difficulty, but with no more difficulty than once you'd understood how the boson could be used between the fermionic degrees of freedom and the fermionic degrees of freedom.

20:00 And what any could have got from that certainly wasn't a candidate for a proton, but basic fermionics. It didn't carry the price of the quantum mathematics. The other thing, it was more like a task that the lecture on, but nothing to do with what happened with the fermionic algebra. If you didn't do this, and which in fermionics there is something, or two things happened to me, I assume, that were very encouraging. Firstly, your student lost his confidence. If you're skilled, the tachyon method works. So when you have plenty of experience, firstly, there was no tachyon, and secondly, the number of dimensions in which you didn't have this anomalous relativistic behavior, not in 26 minutes. It's a moot point whether 10 is better than 26 if you live in 4, but it's certainly encouraging. One of the hares that got set up by this was followed for a long time in a way that 13 people bought the original discussion of strings. And that was something called supersymmetry. Because once you had hares, once you had a string coming out of a string, strings are really theories of two-dimensional services. They're two-dimensional things. It became apparent that these two-dimensional... All of these have been connected before, so the third example of this was a symmetry that was greater than it had appeared before. The charges associated with this symmetry terms were mentioned.

22:30 And this symmetry was termed supersymmetry, or S over Sy. The problem that happened then was that although I'm presenting this as if it was an earth when I see this whole, the rest of the world was chugging on very excitedly outside. The unification of the electromagnetic and the weakening reactions had gone apace and they were now intense. To get a grander unified theory that incorporated the stronger interactions in terms of quarks and the entities that held them together, the gluons. So there was being an attempt to unify QED and the weak interactions. There were problems with that. One problem was known as the Hall-Arch problem. And that is that there are many different mass scales associated with such a thing. And in general, there is no simple way of stopping these mass scales blurring, so instead of having one mass scale associated with a couple of hundred proton masses and another one with a trillion proton masses at a time, merge some of them little by little one by one. It was realized that supersymmetry... We could provide a resolution to that problem, provided we had forgotten its origins and, having seen the idea, realized that it had a much greater applicability than that in the context. So there was a tremendous amount of activity in which people said, fine, strings have supersymmetry, but who cares about strings, because most things have supersymmetry. And supersymmetry is just what we need to handle the creation of grand unifying theory. But next, so this was still in the context of strings, but there was this rather wide avenue with which supersymmetric ideas were taken over to the super grand unifying theory of Suzuka.

25:00 But there is another compelling reason for forgetting the string of origin, and that was that supersymmetry has its most, almost forces you to incorporate gravity, so that the gravity of my theory we got so far had omitted, because we didn't know how to, nobody knew how to handle gravity, but supersymmetry gave us a very natural way in which gravity could be built into. And gravity will have this problem that it's too singular in short distance. But the excitement about supersymmetry was that it gives you cancellation or it gives you long, it gives you a short way to make cancellations to any other method, the bosonic method. So at the same time, supersymmetry naturally incorporated gravity, and it principally incorporated a mechanism that made gravity solvable. So, by and large, the people playing with supersymmetry were decapped to the gravity unified theory patch, and used the ideas that they got to incorporate, to incorporate gravity. We were moving to a unified theory that incorporated all the forces, using all the forces that we knew. So we had supergravity. And a small handful of people refused to be diverted and carried on working with string. The bulk of people moved in supergravity. And then, at that stage, we become sufficiently softened up by 26th and 10th dimension. But it was time to refine the old idea of physicality and climb. But there's nothing wrong with having a few more dimensions around. If you're fighting, you have some mechanism for rolling up the ones that you don't want. And once you've got gravity, you've got a natural scale over which you want to roll the ones that you don't want,

27:30 which is called Planck length, which is around 30 centimeters. So, a few dimensions that only extend to take the mathematics of these enemies down to probably anybody. And we had a prior model making, one of these that I, for many years, provided a prototype for looking at gravity. The idea isn't very difficult at one level. So, it's a relativistic particle, I'm sorry about this. I've got a massless field in five dimensions, and it's going to have this quantum and massless point particle. I say, the equation is going to get satisfied if I call my spatial directions x, y, z, I've got t for time, and call my fifth one u. There are a number of ways that you can write the sum of x, y, and z on the line of, let me use capital X for t, x, y, and z, then I decide that I want to roll this particular dimension up, say in a little circle of radius r, so that u would go to between 0 and 2 pi r, with periodic value conditions, then I would write x u as a sum of e to the i n u over and over r. And then this equation becomes that, mode by mode, I get this times pi n of x is n over r squared pi n of x. Each has its own particles of higher and higher mass, but if R is the pure, if R is immensely tiny, the only particles that are going to play an important role are going to be the particles associated with Y0 of X, which are of zero mass.

30:00 So what one is saying is that if you're going to kill the dimensions you don't want up tightly enough, and you've got particles... Particles with low mass will still suffice, but with low mass you'll get new particles, so something bad won't necessarily bother you. And so in the context of, say, gravity in five dimensions, which was the original producer kind calculation, where alpha, beta goes 0, 1, 2, 3, 4, then what this is saying is as far as the underlying fields are concerned, I need only look at the zero modes, And so of these alphabetas, I've got my ordinary g-nu-nus, my ordinary metric, and then I've got g-nu-4s and g-4-nus, but these are just going to be vector fields, and then I've got the g-4-4s, so that dimensional reduction shouldn't hold too many nightmares. You can just curl up, in principle, you can just curl up the dimension. The problem is, the problem was, though, that even then, starting with supergravity, it turned out that the most, I'll tell you what the greatest potential was in the 11th dimension of supergravity globally, but if you like, you've forgotten anything about strength. And the question was whether the supersymmetry, this balancing of hemionic and bosonic degrees of freedom, would actually make the theory be normalizable, and the answer was you couldn't. And so that's what this, this arrow just hits the bottom, but this whole approach turned out to be that it was, that super-reality wasn't.

32:30 The problem then, well, at that stage, that everything stopped. People were getting despairing, but at the same time, there had been this small trickle of ideas that had followed on and avoided going into their some fruit. It was important that people had done superpepity because we'd already then got all the technology and knew how to think about dimensional quantification. We knew how to handle the ideas associated with that. There was no novelty with that. The rule of thumb, I think, is that you can only curve with one really novel idea at a time, and it at least managed to curve itself with what we said, the rolling-up dimension. What then happened was that there was a problem with the... several things happened, two particularly important. The one thing that was important... What I found was that strings had in them a three-pronged tension that would get heavy at one of the prongs. Now, when we think about the hadron, to determine the tension, you just spin the hadron, you see how much extra mass it gains, and then you subtract that mass from the original mass, and that's what we call tension. And we knew that that was the field of mass. And that was when we were worried about the hat on. One way of getting a point-like object from a string is to keep on cranking up the tension until the string collapses to a point. That was the first thing, was that you looked at the infinite tension limit of these, of these, for something that wouldn't make sense.

35:00 But that didn't make a lot of sense. Because in the potential limit, you found that it was just the lowest mass states of the commonplace stream that survived. And these lowest mass states were massless gauge fields like protons, or cations, or entities, leptons, massive leptons, for example, like neutrino. But on the scales which we're talking about, the left ones aren't very massive, so they could be many. Or they could be many. So these would be the objects that survived, or at least, objects of these quantum numbers survived if you cranked them. Now why might you want to crank up the tension? There's another reason why. And that is that if you've got an open string, you've automatically got a closed string, because there's no way you can stop it, because you won't want to join it. Now before, that had been, not exactly an embarrassment, that had been necessary in the context of Hatton, but it had to be to be in quantum physics. It's now to be to be in because what's, what this is, or what this, the mass, the lowest mass state is supposed to be. And a very good candidate to be built on that is the departure of the... So that the lowest mass state of this string in the infinite tension limit were the candidates. Well, we're very much the same type of field in the supergravity. So that we had all the fields from orbit were present here, but once you've got gravity around, again, the natural mass scale, or the length scale, is the Planck length, and the tension is the inverse of some sense of the sun.

37:30 So if you're saying that in fact these strings are only 10 times bigger... So you'll have huge tensions. Then all the excited states of these strings are going to be entities that have nothing to do with the topology. And so perhaps the string that we've begun with, or that we've modified, we've incorporated, was just the object we were looking for all the time. Because it's not all the quantities that are associated with any of those things. But it has this additional virtue that it's not a point, and that what killed supergravity was the point, was the pointedness of everything, that you couldn't handle the high frequency correction. Once you've got a stream that has some extension, then you've got a chance of having a finite field. So that, for that, for that reason initially, there's the possibility... So what you're looking at is no more than the grand scale of a finite theory. And the finiteness is crucial, if you will. But as soon as I start talking about theories, then I've got the finiteness built into my words. I'm not talking about models where you can poke away and say, yes, it would be nice if you could do this. There is a certain domain in which it makes sense. But talking about a genuine theory that's going to accommodate. All that we've understood so far, then it has to be ultimately finite. And this was the problem for a while. That was the one thing. There was a problem, however, and that is that the anomalies, as soon as I've got gravity in my application, I've got more anomalies than just those that are associated with general covariance. And so although this was a good candidate, these things like this were a good candidate for having the finite theory that you call a deputy for this time, there's no entire reason that you could find any model, that you could find any streams that didn't have anomalies.

40:00 And the great breakthrough came when Schwartz and Green realized that there were strings for the antonomical problem. So we ended up with six candidates. One of the motives behind the initial bootstrap of the early Hadron phase was a disgust with the arbitrariness of a lot of the parameters. But the strength of the electromagnetic field, the electron charge, there seem to be so many arbitrary parameters. One of the hopes of having everything being built with everything else was that this armature NS would be fixed. At this stage, we're not talking in that language at all, but it's fulfilling that original program. Starting off with essentially an arbitrary, an arbitrarily infinite number of theories, we've been painted into a corner in which there are only six candidates. Not only that, once I fix the string tension in terms of applied mass, each of these candidates has only one three parameter assumption. It's concerned with the difficulty of putting the thing in half. So you are almost in a situation where you have six candidate theories with no three parameters. And that is essentially the burden of the advertisement that forced us to choose the one that corresponds to the world.

42:30 This is six candidates in ten dimensions. And what I've got to do now is to get down from ten dimensions. And there is one best candidate. These six candidates are labelled by the Gage Institute as the best candidates. These are exceptional. At this stage, the advertisement is lost because we have to do several things. Look at the compactification of how we're going to roll up. Firstly, there's the problem of compactification, and it would be lovely if there was a natural way to say that this ten-dimensional world in which this thing lives splits up into a four-dimensional world of, well, I shouldn't say that because it's got gravity here, a four-dimensional world of total relativity. Some six-dimensional models. There's a huge amount of choice in doing this. There are particular types of six-dimensional models here, as Scott's got in favour of MacIsaac's later, particularly the habit of flat, but there is still a tremendous amount of that in use. The second amount, the second problem, is associative. And that's, it's perfectly possible for my gauge fields. In these, to have non-zero expectation values, while at the same time, this is for the grand state, while at the same time, the field space in the grand state has zero expectation values.

45:00 So I have a whole set of choices to make as to how I choose magnification. The third thing that I have to do is that these manifolds here have handles, and I have to specify how the flux lines go through the handle. So then there's the whole problem of