How the Structure of the Universe Reveals Its Origins (contd.)

0:00 You might wonder what happens in the end, what is the final effect of all this gravitation interaction on the cosmic expansion. You may wonder, is this object, which is proceeding away from me, going to escape from me, or is it not going to have enough speed and it's going to re-collapse on me sometime in the future? So this obviously depends very crucially on some ratio between the speed of this object and the amount of matter I've got inside me. If I've got too much matter here, then it's clear that this object is going to expand, it's going to stop, and it's going to go back. So the big bang is going to turn up in a big crunch sometime in the future. This is one possibility. The other one is that if this speed is really very large, then this object is going to escape from me at some point in the future but this is a bit tragic as well I'm going to end up with an empty universe an open universe empty I'm not talking about geometry yet it is empty an open universe is empty at late times so I've got this kind of two unpleasant futures for the universe a big crunch where a completely empty universe and in between these two there is a really narrow borderline in which this particle will just escape end up with some reasonable universe, like the one I live in, in fact. Now, the crucial problem here is that I'm walking on a tight rope, and if I move a bit to the side, I should end up in a T crunch. If I move a bit to the other side, I end up in an empty universe. And this is a problem of fine-tuning. So this is a problem of fine-tuning which, in fact, is much more serious than what I've made it sound like. If you actually put numbers into this, you end up with a conclusion that the universe should have re-collapsed or become completely empty in the first very small fraction of the universe, which is, of course, wrong. It's a contradiction. The crucial thing about inflation was to show, and I think more probably we'll talk about this more, what inflation shows is that it's crucial to have accelerated expansion or attractive gravity for these arguments to go through. what inflation allows you to do is to actually fine-tune the universe and in fact the only stable universe if I have accelerated expansion is the universe which I initially I said was a tightrope it becomes a valley suddenly the tightrope becomes a valley on which every universe is going to be tuned so inflation has been important not just to explain observation but also to explain things

2:30 which otherwise would be uneasy about the early universe you might not think they're an easy. You might think the universe is just fine-tuned. That's the end of the story. So inflation is perhaps the leader in the current theory is trying to explain the early universe. Let me tell you about another theory, which is called topological defects. And this is a theory really which attempts to explain really what we observe only, and it's structure formation, that's the emergence of galaxies in the universe which is very nearly homogeneous and the kind of physics which goes into this type of theory is very different which is why i decided to tell you about this different type theory because just give you the balance kind of things you can do so the crucial idea about different theories is the view that the vacuum in modern physics is not just nothing so in newtonian mechanics the vacuum is nothing exist, that's it. In modern physics, it is a very well-defined state. You don't need to know what this means. I can just tell it's represented like this. The vacuum is not just zero, it's zero with a bracket. So what the vacuum is, is like a state on which I build reality, on which I build particle states, if you want. And it's even more complicated in field theory. The vacuum is a configuration of fields, which minimizes the energy, and which need not be trivial. is something which can be quite tricky and even more so when I consider theories in which I can have different vacuoles. The theories with degenerate vacuoles, which are all equivalent, so the reality is I build on top of the pitch of this vacuole look all exactly the same. But nonetheless, I have the option. I have the choice at the start between a variety of vacuoles. I should say this type of theory, again, this might sound completely far-fetched, But this is the type of theory which explains what I observe in accelerators, things probably worried about massive gauge bosons, things like Zs and Ws and all that. I could not possibly compute the predicted properties which I've observed with theories which did not have these properties. So the idea of the generate vector has been very useful in modern particle physics. and what topological defects are are an attempt to take what I have observed

5:00 in the lab, the accelerators in the cosmology, to the universe and see what happens so what happens is actually quite curious what happens is that I find that most of the period I observe in the lab have a phase transition a bit like when you go from water into ice when you lower the temperature In fact, it's not just as if I have this situation with a single vacuum, or this situation with various vacuum. In fact, I can go from one to the other as a lower temperature. And it's a bit like going from water into ice. There's a critical temperature below which I can choose from any different vacuum, above which I have only one vacuum. Now, this is quite interesting if you put this in the context of the early universe, Because, of course, as I go back in time, the universe is getting more and more concentrated, hotter and hotter. And therefore, the space transition should actually have occurred in the early universe. The universe should have gone between this situation and that situation. If you combine this with the fact that the early universe is actually divided... See how I point into a film? Sorry? It's the arrow, or not? It's the arrow, or not? I mean, this is the arrow of time. Yeah. Which is the coolest thing? This is cool. Sorry, she's wrong. This is time, actually. So as time goes, as it goes into latent times, you're going to lower time, actually. Yeah, sorry, she's wrong. So anyway, if I put this kind of situation into an early universe, which, as I told you, is divided between all these horizons which one knows about each other, a rather shocking possibility that there's no reason why different horizons should have chosen the same vacuum as you go from this situation to this situation. So I may actually divide the universe into all these domains, each of which are in different vacuum. This is called the Keeble Mechanism, and this is very interesting because then you have to ask, what happens when I go from one of these domains to another of these domains? I've told you that the realities built on each of these vacuum are all equivalent, so it's as if this thing is different from this thing. But what happens when I go across the boundary connecting these types of things? Well, then what I have is really a defect in the vacuum.

7:30 Which is called a topological defect. I don't even know why, but anyway. As I go from one vacuum to another, I must necessarily go out of the vacuum. But it's a bit like having a defect in the vacuum, which means where something which is now not just a vacuum state, something which has a gravitational field, something which exists. So a topological defect is really this kind of funny thing which exists in between these different domains. It can take many different types of morphology. It can be strings, it can be walls. And it's a curious prediction of the early universe, because it goes in the universe, which is very homogeneous, and which goes through this phase transition, must necessarily have some kind of structure in it already. It must have these strings, it must have these walls all around. This is an interesting idea, which was first put forward by Tom Kibben in the late 70s, and which has been very useful, very predictive, for explaining the structure of the universe. This is a simulation of cosmic streams in the universe. Just a box of worms, essentially. these things just move around and the crucial thing is that because they have a gravitational field they can interact with this homogeneous background and create an homogeneity they can actually explain things like structure formation in the early universe they can come up with predictions for what the cosmic radiation should look like and even that with things like this mark. The moon is about an half of this mark. So this is not an All-Sky mark, a very tiny mark of what the cosmic radiation should look like. And you see the cosmic strength. You see all these worms. Basically, they appear as kind of gems in the temperature. And this is pretty different from what inflation predicts. This is what an inflationary theory predicts. Inflation just predicts this quantum noise, which then gets amplified into very large scales, cosmological scales. The point of noise doesn't have any structure. It's just noise. So I think the important thing with Chatham since the COBE satellite experiment is that cosmology is not a field in which you can't just say what you want. When I started my PhD, I could say whatever I wanted was perfect.

10:00 Ideal ground for it. My theory is that since the COBE experiment, I think it's pretty clear that you have to be careful, you have to predict it may run into conflicts. And the Covey experiment does not have this resolution. It does not have this angular resolution. It's an experiment which covers the whole sky with a very poor angular resolution. So you can actually not distinguish between these two types of theories. But it's important that these things happen because it can only be right to allow yourself to be wrong. And since the Covey experiment came up with these maps, now I can be wrong, so I can be right as So let me finish, basically this finishes a bit of summary about the two paradigms in modern cosmology, the ones which actually connect directly with the experiment. And let me just summarize the two parts of my talk. The first one, which was about what we know for a fact, the second one, which was about the theories. And I thought about observations, and I think I showed you the various layers into which one can go. I showed you the layer of the galaxies, of the clusters of galaxies, of the quasars, and of the cosmic radiation. And you see that initially there is not a kind of consistent picture appearing. I don't even see homogeneity, because I go further and further in space, deep in the distance, and therefore back in time, I see this idea of an homogeneous universe emerge. If I go even further back, then I see quasars appearing, and this means evolution, means an evolving universe, which was not the same at all time. And if I combine this with expansion, this kind of puts me in a good shape to predict a big-bang model, a model of the universe in which there was a creation event. The universe has expanded, homogeneous. The crucial facts, nevertheless, which will tell you more about the early universe are that the universe is not exactly homogeneous, that there's only small fluctuations on top of it. And I think most of the modern cosmology, the retro cosmology, has been an attempt to explain in detail what these structures are. It's actually quite difficult to predict exactly what happens at the level of quasars or galaxies. In fact, the cosmic radiation has been the

12:30 ground for testing these various theories and the reason is simple it's because it's the oldest remain of the early universe which therefore has not been processed by the evolution of the universe so much so now I've described these two main ideas I've described inflation I've described defects the first theory is based on the idea that gravity was repulsive in the early universe and this is really kind of something which is based on a different type of matter content in the early universe and I told you how inflation could predict the observations and also fine-tune the universe and then I told you about another theory which is based on the idea that the vacuum is a very complicated structure and that therefore should be topological defects in the vacuum and I told you how this theory, topological defect theory could predict the observations in the microwave background so in the next few years I think it will be interesting because it will be very clear which of these two paradigms, if any of the two, is right. And in fact, I should say it's possible to combine the two as well. You may have a liberal-democratic approach in modern technology. And in fact, I'm advocating it, because you have one more parameter. It's obviously you have one more parameter. So anyway, I hope this was kind of an overview, a good overview. Okay, thank you very much. It's fascinating, wonderfully illuminating. Thank you very much indeed. I don't know how many of you regularly look at nature, but some of you may have seen that there was a reference to this gentleman in last weeks because he and some colleagues have been doing some observations at a higher resolution than Toby was able to of the cosmic microwave background. And what they found does not appear to be consistent at any rate form of inflationary theory. Is it more consistent with the topological defect theory? Or does it not really address that issue at all? Well, the problem with topological defects is that it's extremely difficult to compute anything with that. So we can't compute things at the level at which we computed things in inflation and which address a particular observation. So I don't know. topological difference could predict the type of pitchforks, it's kind of non-Galcianity, but it's something we don't know.

15:00 I mean, essentially, we now have access to huge computers, and topological difference finally are becoming predictive because we're making use of these big computers. But we have not got yet to the level where we can compute a particular signal which we found in the sky. But you found it isn't quite like noise, in effect, at least not the simplest form of noise, the galaxy. Well, I mean, what we found is essentially that something which is not consistent with inflation, but we don't know if it could be predicted by defects. I see. Because that means computing something you can't compute with defects. I understand. So it's a mark against inflation, but not particularly a mark for defects. Are you telling us that there are no quasars nearer than a billion light years, and no clusters of galaxies further away than a billion light years? Well, there are some galaxies very far away, where quasars are. Oh, there are quasars near them? No, I know. Okay. Earlier you said that, if I heard this right, that the speed of the expansion of the universe is such that at the present moment, light proves about two light years instead of one. Does this have any significance, does the figure have any significance, or just coincidentally? No, it's to do with the expansion rate of the universe. I mean, this is not the local speed of light, this is the global speed of light, which results from expansion. It just seems an interesting coincidence that it should be doubled. Well, it actually depends. You know, the universe is not dominated by Mars, but it was dominated by radiation earlier. And there it's free. It's not two, it's free. I mean, there's nothing special about the universe. On this point about the distance of quasars, are you saying that you do not see quasars, or indeed a couple of galaxies, beyond a certain distance, and is it actually as if were a phaedal? It's a phaedal. It's a phaedal. It's a phaedal. It's a phaedal, it's a phaedal, it's a phaedal, it's a phaedal. Yeah, I mean, there's a period which is called the Dark Ages, which goes in between the emission of the cosmic radiation and the first quasars, as you can see. And this period really just reflects the fact, maybe, that these things are put down into this thing.

17:30 And this means, this is actually, again, prime ground for theories, because you can't fill it with anything. I mean, well, by a trade-off, I mean, you know, the telescopes are not strong enough to see it. It doesn't mean there are things I get in front of them. In these typology defects, is it a defect in the boundaries, or is it a defect in space? Is it a defect in the ecology of space, John? I think you probably said what you said. So it's, no, it's in the boundary. I mean, what this means is, if this bit shows, say, vacuum one, and this bit shows vacuum two, there will be a wall in the thing. No, what this means is that this thing exists. This thing is actually a field configuration, which has more energy than this one and this one. Therefore, it's not a vacuum. So kind of to interpolate between these two vacuum, I must go out of the vacuum. So I must end up with something which is a gravitational field, whereas this doesn't. What's that feel short, Mr. Balancing? It's pretty short. I mean, it depends on the theory, but it's tiny. We're talking about really, really small. So it's... And then the idea is that the matter will be drawn because it has a gravitational field associated with it. And so you would expect to find a pattern of the layout of galaxies, which is a reflection of the initial distribution of topological... In fact, I didn't mention it, but the clusters at some states, they seem to be kind of organized in worlds. But this can be explained as well in theories like inflation, which you consider all the evolution in being true and so on. So the cosmic radiation we lose in place, we're actually able to distinguish between quantum noise and this kind of thing. This thing should be the very distinctive part. Because both inflation and topological defect theory predict more or less, or at least are consistent with pretty much the same kind of distribution that we actually see. So it's more this kind of feature that we have to do. Very much a layman's question. I'm puzzled what you're saying about clusters of galaxies.

20:00 Now, if you have one or two quite large central galaxies, they may attract other galaxies to move around a central path. Now, if that is the case, the observation from Earth would be, when they come around the other side, they would be moving towards us, not away from us. Is that not so? So you're talking about cuter velocities on top of expansion. which are due to these tendency for things to accrete. And you're moving away at the same time, moving towards us. Yeah, it's a small, the correction is very small. But the effect exists. Is that happening? This is called q-velocity. I mean, it's actually a very discriminative observation to find between different types of universes. Every theory which explains existence of galaxies must explain corrections to the cosmic expansion because of the effect you just mentioned. different theories put in different directions yeah the security is moving it's going on with my lady question if this is so but is it not possible there that other relaxes will be move move Bradley towards a large group it's kind of a trade trade or a bigger group basic trade-off because the thing is never strong enough to counteract cosmic expansion completely are they all expanding at the same speed? Is it true that everything is expanding, inflation is at exactly the same speed? Well, the idea is that it's the same, well, it's the same public constant locally, if you want. It is not. If the question, if the answer to that question, the different galaxies, the different densities, are not expanding at the same speed these others, then you're into a very complex situation. I think what you're saying is there's the overall effect of cosmic expansion, which is the dominant effect, and the things you've just been talking about superimposed on the top, but they are small comparisons. Are we to assume that these defects are significant in their effects in the early universe, and they're relatively weak, direct effects from them in the present universe? No, the idea, okay, for instance, walls are a disastrous scenario because they have exactly the effect if you dominate the universe.

22:30 So normally you have to get rid of them. In fact, you use inflation to get rid of them. That's a different point. But with things like strings, which we consider to be non-pathological, we say they're not pathological because they interact and they decay in such a way that they remain in the universe at the same fraction of the overall density of the universe at any time. We say they escape. And this is the reason why they're important. They don't dominate the universe, but they don't disappear. They're all disappeared. They're always a few of them. In which case, they all can see that they'll be detected. They will run. They will run. Between quasars and clusters, all they can see would be clusters and clusters. They're superplacers and so on. But those are very question mark entities. I mean, it's kind of difficult to define them. As I said, there's some kind of evidence for this kind of Hanukkah-structuring universe in which clusters are themselves distributed on worlds by Hanukkah. Charles? They remind the incredible amount of light that quasars emit, and how far away and less than how far back in time they are. They give us a very strong signal. What does this tell us about their composition? in terms of, I mean, are they purely the lightest elements or how far up the heavy element spectrum do they go? Well, they're mostly hydrogen. The question is, I mean, it's very difficult to come up with an astrophysical construction which radiates that much. And the models which work better possibly exist for black hole in the middle of the laser. And it's one of the few ways of having an engine which can produce so much energy. other elements. It's more like you need some strong gravitational field somehow in the middle of the quasar, which we can't see, to generate this amount of radiation. Spectroscopically, what do they show? Oh, there's all kinds of stuff in small amounts. Magnesium and things like that. It's mostly hydrogen. This is carbon? Yeah, but there's always some carbon. This doesn't mean that much. I mean, it's more... So there's this thing called Lyman alpha clouds, which are clouds in front of quasars, which have these absorption lines from which I can actually find out the chemical composition of all these things quite accurately. And yes, you're right. I mean, these elements are there, whatever the significance. I don't know. But it's actually a lot of contradiction in models of kind of nuclear fusion.

25:00 Could you speak a bit louder? Could you speak a bit louder? Oh, sure. That's all. I can round for another one. Early on, you transiently mentioned conservation of energy. It was part of your dismissal of the steady state theory. It seems to me that there's all this paper of the vacua totally drives a culture process through conservation of energy. It's a different level. It's a different level. I didn't dismiss the steady state universe. I like it very much. The last paper I wrote actually posulates violation of energy conservation. This is not a personal view. But there's a different level. There's a fluctuation which violates energy conservation. It's not an average. It's not a classical effect. It's a different level. I'll come to the defense of that question. When Hoyle and Co. initially posulated these steady state theory, to say that they weren't going to buy conservation of energy. But then later they developed a theory where they had a negative energy field. And you now have people like Nalika saying that this is very much what you get in inflationary theory. Inflationary theory is just the negative energy field back in business. No, it is. The energy is positive. The pressure is negative. It's a technical matter. I know it is. I know it is. It's very different. I mean, I can come up with few theories which have negative pressure, but positive energy, that's kind of, it's very difficult to come up with negative energies, although you can't do it. Well, the thing is, the way that gravity works in the integrity, it's possible to treat the gravitational force as a source of negative energy, and then you get... Well, sorry, I mean... No, the crucial issue there is that one thing is the gravitational mass, the other thing is the mass. And the gravitational mass is a combination of what we call the energy density and the pressure. so I can have a positive energy density and have a negative gravitational mass if I have a field which is very tense tension means negative tension so very tense this is an effect of general relativity by the way, if you have an object

27:30 with a lot of pressure, it actually attracts things more so if you have an object which is very tense, it attracts things less and if the pressure is very negative it has to be very negative then you actually have repulsive gravity But I'm not making this big negative. Without going into all this, I'm just trying to find out what enemy has to be right in the song of what he has. Granted that Dalek is rather a good physicist, you know. No, I'm not a good physicist. I'm not arguing against that. But what I'm saying is inflation in a way is a step beyond that because it comes after the construction field theory. If it actually realizes it. I'm not just postulating this big or negative. this is a cosmological constant if you want cosmological constant is a positive energy with a very negative pressure it's exactly the same charge it's very well trying to acknowledge you know of the universe unlike the universe it's expanding would you say that that the existence of the universe is really forever and never well that depends on this issue i mentioned if you're going to recollapse if it's going to go forever we don't know it looks forever the best measurement so far okay all of it is it's why it is just in our north i don't know what you mean well we don't know we don't conjecture we have theories but in the ultimate when we ever have like a universal theory that tells you how the universe was created because at the moment it's all theoretical it's always I mean, I can't experiment with the universe. The experiment has only been made once. All I can do is play what exists and infer things from what exists. Well, we hope you can't experiment. Yes, Peter. Very simple question. Is there anything to possibility that this whole thing has gone wrong at the first place because we misinterpreted the redshift? Is there any other way to interpret the redshift? As I said, there's many more minimal hypotheses explaining just the theory of the tired photon photon. You could say light just got tired. In fact, this is, this was popular in Cambridge in the 50s, in 2000.

30:00 But you can't explain everything with that. I mean, of course, there's always... I'm just asking you. I mean, do you think that you just dismiss that? It's not worth it. I don't even have an opinion. It's just a matter of faith. I mean, I really, I prefer the red ship explanation. And this is a matter of faith. And I mean, I prefer it because it explains more things. At the end of the day, there's this huge amount of faith, which this theory of the Big Bang can explain. in a way isn't that the answer to the question here that there may come a time where you have a theory which is remarkably elegant and explains pretty well everything in what doesn't look like an ad hoc way and more data comes in but it just confirms it more and more and at a certain point people quite rationally assign it a very high probability of being at any rate broadly correct that's what getting to the truth That's what getting to the truth means, pragmatically, in science. I thought the question here was, we don't really know what caused the Big Bang in the first place. It may even be a stupid question to ask, what caused it. Well, that's Chris, I know. That's Chris's talk, it's my talk, I don't know. There's many different views on this. Some people think there is a quantum approach which removes the Big Bang. In fact, I should have mentioned, this is quite curious, which I mentioned in the beginning, which now are living in the West, they're coming up still with theories on their creation. And Lindbergh came up with this theory of chaotic inflation, and chaotic inflation does not have a creation in them, because quantum gravity just removes everything, becomes a foge, such as a script, which exists forever in the past. I'll speak on the lines of the ridiculous, but why the Kobi pictures, what, I'm having to think of the circular. Well, there's many ways of projecting the sphere onto the plane. So, I mean, this one's quotient. I mean, this is like a picture of a map of the Earth, of the Earth, the continent. It's the same kind of projection. It is very... I mean, you must have seen maps of the Earth, which are like that. What's that projection called? Is that the Mercator one? No, it's not the one. one was that it doesn't matter it's a knife of projection i remember so yes i've heard that there's going to be some massive improvement on the kobe experiment it's going to be sent up

32:30 sometime in the relative near future do you have any clue why not yeah so there's an american experiment called the mob satellite which is projected to be launched in the year 2000 with data two years later and what's the factor improvement it's an improvement in resolution So it's an all-sky mark, again, improving the resolution up to... So COBE has a resolution of seven degrees, seven moons, whereas this thing is up to the degree and up to the resolution. And what do you expect that new resolution... What questions do you expect this high resolution to answer? What important questions are at the moment to expect to be answered by that? Well, some people... I don't know. It's going to be most... I mean, most theories predict the same thing as far as the Covey resolution is concerned. But defects and inflation are going to predict very differently. And, well, I don't know, the best... There's a thing called the power spectrum. Anyway, never mind. Which actually is very different. And if you start making plots of these things, it's just totally different in defects and in inflation. And furthermore, they're very sensitive to things which are normally pre-parameters. Like, what is the Hubble constant? which means what is the age of the universe what is, how much matter in the universe is made up of baryons, which is what we see how much is dark matter or things like is the universe open or closed is it going to expand forever or not in that case, could you come back in 2002 I should say before 2002 there's lots of balloon experiments going out which are cheaper In fact, they're flying now, even as I speak. And these things are already going to be great improvements over COVID and should actually settle some of these questions already. In particular, the question of whether the universe is going to expand forever or not. So, how is it going to do that? To decide whether the universe is going to expand forever or not? This is to do with this thing I mentioned. I was thinking, but anyway, what this is, is... So I have this question, how much power there is in these fluctuations on different angular scales? So I have these kind of plots. And we change scale and then power. And initially, all the theories predict the same, there is some kind of curve like this. And ECOBI has measured this kind of large, this is actually small scale in this direction,

35:00 large scale in this direction. And then this thing rises as a kind of rise in the power, as a kind of peak. And the place when this thing rises depends crucially on whether the universe is going to expand forever or not. So, marking the position of this peak is going to decide the question. Any other questions? The gears are also silenced. on this question about I'm right in thinking that recent observations of supernovae type 1a supernovae in distant galaxies appears to show because they are fairly good standard candles that they the kind of supernova that tends to be intrinsically the same amount of brightness within a certain margin wherever it happens This appears to show not only that the universe is expanding too rapidly in relation to its density to come back together again, but it looks, in fact, as if the rate of expansion is actually increasing, that we're living in an accelerating universe. Is that not right? That's what would be remarkable. Well, I mean, as with every kind of experimental result, we have to wait a bit until the dust settles. It's quite easy. I mean, I speak from, like, this paper in nature about how we work. I agree, it's the same. We have to wait a bit before we can say that. So it's to do with this plot I've put earlier on. Check and find it. Let's see if I can't find it. Yeah, here it is. So I told you the universe is expanding, but it's accelerating. And I should be able to see that if I look far enough. At some point, you won't have a proportionality dependence and you can kind of deviate from it. And in particular, whether it's accelerating or accelerating is going to be obvious. So what the supernovae thing is... So what will happen? What they found is that you've got something like this. Isn't that right? Goes down. Oh, sorry, goes down. Which means it won't cut up, really. Yes, that's right. Okay, so it does that. that. And if that's

37:30 for real, that's just... That means we have inflation now. That's exactly what it means. It means we have repulsive gravity now. It means we have a cosmological constant. That's what this thing is. So gravity is dominated by another capacity. So this is a result of Schaffernberg in terms of we have to wait until this happens. But what this means is that this is the end of the universe, of course. Is this related to the constant that Einstein put into his original equation? It is that. Or effectively it's the same. If it's not the same, smart people are effectively in the equation. Yeah, but it reflects the energy of the vacuum. And the energy of the vacuum is this problem. Pressure is mine as well. So this means the gravitational mass is actually negative. So the cosmological content is repulsive. Maybe this is now just getting more thoroughly continuous. I said the basic. which switches on and disappears. Ah, yes, I see. Whereas this is different. It's one that keeps life on going. I just had a thought if there was any clue if it was in fact the same process that had some time dependence of declining in power, and if that would show earlier in this Hubble diagram. You mean a very logical constant? No, a cosmological constant that fell in time according to some equation, rapidly at first, unless it's a very interesting theory you ought to be able to see that it's very popular now because I mean that theory actually can explain lots of details about like the distribution of classes and things like that it's not just an explanation of supernovae results it's actually very predictive if you put the time dependence in cosmological content it's really nice I think we'll break now for tea but thank you very much Thank you.

40:00 Oh yeah, yeah, I thought I looked like that. Thank you. I know I was going to ask you a question. Do you know about these films? Do you know they're all in the library? Yes. It's one second, isn't it? Well, I know. Can you get in there? Yeah, but do you know, I'm not sure when they're open. They're open until Sunday morning for about three o'clock. That's right. So do you know what happens without some people doing that? Because I think there's a... Oh, um, you know, I think it's, uh, I didn't see a week from it. Yeah, I don't know. I don't know if it's going to go back. I think it's going to go back to it. Cool. Cool. Yeah, I don't know. Thank you.

42:30 Thank you. what you want Thank you. Thank you. Can we get to this enemy level? Yeah. Yeah. It's an old building on the back of the school board.

45:00 It's an old building on the back of the school board. Well, I didn't even think of it. Well, I don't think we're in some sort of a cycle, but there's other forms of it. Yeah, that's easy. It's beyond our presence. Yeah, that's easy. Yeah. And that sounds look like other things. I'm showing him the view that I am. I don't understand. Thank you. Inside the room that we came out of, you know, our room, there's a shelf where they've got the team-making things, and I think there's two, two, two tables, two tapes there. You really can see that. Yes, you know, our room, where we're sleeping, well, there's two tapes in there, on the shelf, where, you know, if you have a chance to give you the key, you have the same key that you came out of. There are two like that, two tapes like that. Thank you.