1 00:00:14,310 --> 00:00:19,710 Good afternoon, ladies and gentlemen. Can everybody take a seat, please? 2 00:00:20,190 --> 00:00:26,190 Thank you. So it's my pleasure to welcome you to the second Western Lecture. 3 00:00:26,220 --> 00:00:29,040 These lectures occur once in three years. 4 00:00:29,070 --> 00:00:35,690 So in astrophysics, we have the highly lecturer for two years, and then we have the Western lecture and then two years, the Halley Lecture again. 5 00:00:35,700 --> 00:00:39,030 So it's wonderful to have this opportunity to celebrate our subject. 6 00:00:39,510 --> 00:00:44,610 And this year actually we have some additional sponsorship, 7 00:00:44,610 --> 00:00:50,099 the foundation having a workshop in Oxford this week and they decided they wanted to sponsor the lecture as well. 8 00:00:50,100 --> 00:00:53,459 So we were happy to to take their largesse. 9 00:00:53,460 --> 00:01:00,750 And Christchurch College, Christchurch of course also sponsors the lecture series and the workshop that we've been having. 10 00:01:00,750 --> 00:01:08,010 We're having a workshop on stimulating the universe in Christchurch for a couple of days and many people in the audience are attending that workshop. 11 00:01:08,610 --> 00:01:12,839 So far I think we've not quite got to the stage of rooting out the necessity to observe the universe, 12 00:01:12,840 --> 00:01:15,000 but we are doing pretty well at simulating the universe. 13 00:01:15,870 --> 00:01:25,109 So so it is my great pleasure to introduce to you this evening a person of great distinction and a very good friend of mine, Carlos Frank, 14 00:01:25,110 --> 00:01:30,960 who is the professor of astrophysics at the University of Durham and director of the Institute for Computational Cosmology. 15 00:01:31,560 --> 00:01:35,670 Karwal sees a star of our subject in a subject that has bright stars. 16 00:01:35,670 --> 00:01:36,750 He is a supernova. 17 00:01:37,680 --> 00:01:48,570 There are there are many awards and prizes that he has been awarded a list far too long for me to list all of them, and I will mention a few. 18 00:01:48,750 --> 00:01:51,990 Last year he won the gold medal of the Royal Astronomical Society. 19 00:01:52,350 --> 00:02:02,190 In 2011, he shared the Gruber Prize for Cosmology with his colleagues Mark DAVIES, Georgia staff here, and Simon White for the Cold, 20 00:02:02,190 --> 00:02:10,890 Dark Matter Paradigm 2010, he won the Institute of Physics Hoyle Medal, and he was elected a fellow of the Royal Society in 2004. 21 00:02:11,610 --> 00:02:14,879 So it is my great pleasure to introduce to give the second worth of lecture. 22 00:02:14,880 --> 00:02:18,390 Professor Carlos Frank, how are you? What is this? 23 00:02:18,390 --> 00:02:21,480 Talk about your title. Everything. 24 00:02:21,840 --> 00:02:25,110 Everything from nothing. How the universe was made. Carlos, thank you. 25 00:02:33,210 --> 00:02:37,140 But thank you very much. But we're very happy to be here. 26 00:02:37,140 --> 00:02:39,270 And thank you for that very nice introduction. 27 00:02:39,300 --> 00:02:44,490 I'm glad you stopped because you were making me start looking forward to my own talk, which is never a good thing. 28 00:02:45,090 --> 00:02:56,340 So yeah, I'm glad you remember the title because it is kind of a somewhat cryptic title, everything from nothing or how the universe was made. 29 00:02:56,340 --> 00:03:03,930 But I hope in the course of the next 50 minutes or so, the reason for the title will become apparent. 30 00:03:05,270 --> 00:03:09,559 So it's clear not just from the title, but from the picture behind it, 31 00:03:09,560 --> 00:03:13,730 which I should say I put it here to make Roger and your film nostalgic for Darren, 32 00:03:13,730 --> 00:03:19,820 because Roger and I were colleagues in Durham for many years, and that was the view we had from the roof of our building that. 33 00:03:20,180 --> 00:03:29,360 But as is clear from the title, these two talk about cosmology and cosmology is possibly the oldest science 34 00:03:29,720 --> 00:03:33,560 and it asks some of the most fundamental questions that not your scientists, 35 00:03:33,560 --> 00:03:38,450 but many other people ask questions such as How did the universe begin? 36 00:03:39,320 --> 00:03:45,530 What is it made of? How did it evolve to its present state and what does the future hold? 37 00:03:45,830 --> 00:03:55,580 So these are questions, fundamental questions that go back to the beginning of human civilisation and what could even say that civilised 38 00:03:55,580 --> 00:04:00,860 the beginning of civilisation is defined by the moment where our ancestors began to ask these questions. 39 00:04:01,300 --> 00:04:07,160 The question questions of great interest in many disciplines, but in cosmology and in physics, 40 00:04:07,430 --> 00:04:11,360 we have a particular way of trying to address these questions, 41 00:04:11,360 --> 00:04:18,380 which is following a very well-established and well-tested methodology, and that is the methodology of physics. 42 00:04:19,340 --> 00:04:21,890 So modern cosmology is based on the laws of physics. 43 00:04:22,130 --> 00:04:27,410 And for those of you who have the misfortune of not being physicists, let me remind you what a lot of physics is. 44 00:04:27,890 --> 00:04:40,100 It is essentially a rule about natural phenomena, rules that are almost invariably derived empirically by through laboratories and observations, 45 00:04:40,700 --> 00:04:46,850 and then that expressed mathematically and manipulated through the powerful language of mathematics. 46 00:04:47,480 --> 00:04:51,860 An example is Newton's law gravitation. I'm sure you're all familiar with that. 47 00:04:52,610 --> 00:04:56,870 The God's law, Boyle's law, quantum mechanics, relativity. 48 00:04:57,170 --> 00:05:03,140 These are all examples of the laws of physics. Now, as I said, the laws of physics are discovered here in the laboratory. 49 00:05:03,950 --> 00:05:10,040 And in principle, we have no right for those laws to apply outside of laboratories. 50 00:05:10,050 --> 00:05:17,570 But one of the amazing features of modern astrophysics and modern cosmology is the realisation that the very same laws of 51 00:05:17,570 --> 00:05:25,969 physics that we use here on Earth seem to describe phenomena everywhere in the universe at all times when conditions were very, 52 00:05:25,970 --> 00:05:31,040 very, very different from the conditions that prevail in the laboratories today. 53 00:05:31,490 --> 00:05:35,690 So the universality of the laws of nature is a very profound aspect of a 54 00:05:35,690 --> 00:05:41,120 universe which I just going to take for granted in the remaining of the stock. 55 00:05:42,670 --> 00:05:46,270 Now. And so the. Title. 56 00:05:46,270 --> 00:05:51,340 Going back to the title, as I said, Cosmic history is a story about nothing. 57 00:05:51,940 --> 00:05:57,429 So I'm going to spend 50 minutes talking about nothing, and you might wonder why you're not outside enjoying the sunshine, 58 00:05:57,430 --> 00:06:01,420 but I hope you will not regret it at the end of this lecture. 59 00:06:01,870 --> 00:06:09,430 So let me tell you a little bit about nothing. And in fact, as the title says, I'm going to talk about had nothing, became everything. 60 00:06:09,440 --> 00:06:15,580 So let me tell you what I mean by nothing, because I'm using the word nothing in a technical sense. 61 00:06:15,880 --> 00:06:21,910 I'm using it in the sense that we use it in physics, where by nothing we mean the vacuum. 62 00:06:22,630 --> 00:06:30,130 And it turns out that contrary to what the word might conjure, the vacuum is not empty. 63 00:06:30,220 --> 00:06:35,680 It's actually full. It's full of something that we call vacuum energy. 64 00:06:36,070 --> 00:06:43,300 And what we will see, this vacuum energy plays a key role in the entire evolution of our universe. 65 00:06:43,510 --> 00:06:49,450 So I have a animation of the vacuum and so as close as I could get. 66 00:06:49,900 --> 00:06:52,450 So let me tell you what we mean by vacuum in physics. 67 00:06:52,780 --> 00:07:01,480 Imagine you have a chamber in the laboratory and you connect it to a pump and you extract everything out of that chamber, 68 00:07:01,840 --> 00:07:06,740 every single atom, until you have no atoms, nothing left in it. 69 00:07:06,760 --> 00:07:11,560 Of course, we cannot do that in practice, but at that point, you would have a perfect vacuum. 70 00:07:12,250 --> 00:07:20,200 Nothing. And no matter in it, nothing in it. And if you were able then to go and look at what was left inside this chamber with a very, 71 00:07:20,200 --> 00:07:23,590 very powerful microscope, this is exactly what you would see. 72 00:07:24,010 --> 00:07:30,220 You would see that the vacuum, even though you've emptied it of everything, is not empty, it's full of energy, 73 00:07:30,370 --> 00:07:37,450 and that this energy manifests itself in matter and anti-matter that are spontaneously created out of nothing. 74 00:07:38,170 --> 00:07:44,020 Particles of matter and antimatter that when they collide, they inoculate producing energy, 75 00:07:44,380 --> 00:07:48,760 which then decays into matter, and antimatter which then decays into energy. 76 00:07:48,760 --> 00:07:50,500 And this is going on and on and on and on. 77 00:07:50,530 --> 00:07:59,769 The vacuum is actually bubbling with matter and anti-matter, and that is what we mean by the vacuum and by the vacuum energy. 78 00:07:59,770 --> 00:08:06,670 The energy of nothing. Now, I hope you survive that. That's the hardest part of this lecture and may get easier from now on. 79 00:08:07,090 --> 00:08:16,030 And what of the most amazing propositions, not just of cosmology, but of the whole of science today, is that everything we see in the universe, 80 00:08:16,270 --> 00:08:25,180 including galaxies, including stars, planets, and eventually all came out of the vacuum, as I will now explain. 81 00:08:26,020 --> 00:08:34,959 Now, so the up for us cosmology is the smallest unit of interest really is the galaxy and these are 82 00:08:34,960 --> 00:08:42,130 the building blocks of the universe structures or collections of up to 100 billion stars or so. 83 00:08:42,550 --> 00:08:44,620 And that many of these around the universe. 84 00:08:44,950 --> 00:08:54,159 We live in a galaxy very similar to this one and we are here located two thirds of the way from the centre of the universe on purpose. 85 00:08:54,160 --> 00:08:57,160 Because all my colleagues in physics think I agree with them. 86 00:08:57,160 --> 00:08:59,559 They always think that at the centre of the universe here in Oxford, 87 00:08:59,560 --> 00:09:05,350 I have to keep reminding them that that's not true, that two thirds of the way from the centre of the Milky Way. 88 00:09:06,430 --> 00:09:12,610 Now, so let me try and give you a flavour of what I'm going to be talking about by showing you a movie. 89 00:09:12,790 --> 00:09:18,550 Now I just I wonder whether we can get the lights down so you can see these. 90 00:09:18,850 --> 00:09:30,010 Oh, I can do that myself. Right. Aha. You should see me trying to do this in Durham and up surrounded by a cloud of undergrads who say to me, 91 00:09:30,040 --> 00:09:33,070 You're the professor, Roger, you're the professor. 92 00:09:33,430 --> 00:09:37,000 You go now. So even lower. 93 00:09:37,330 --> 00:09:40,360 Yeah, let me see. As low as we can get the. 94 00:09:40,480 --> 00:09:45,340 Okay, so we will. So this a tour around our local universe. 95 00:09:45,340 --> 00:09:48,669 It's a movie made from real astronomical data. 96 00:09:48,670 --> 00:09:53,440 All the data in there are real and it's a movie thank you graduate that was 97 00:09:53,440 --> 00:10:00,460 made by a colleague in Hawaii called apparently whose name you can see there. 98 00:10:00,880 --> 00:10:04,630 And that is an animation that will take us around a local neighbourhood. 99 00:10:04,630 --> 00:10:11,110 And we begin by heading towards the constellation of Orion, which I'm sure many of you will recognise. 100 00:10:11,470 --> 00:10:21,370 And here is a strange object called the Orion Nebula, which is a cloud of gas and dust where young stars are continuously being born. 101 00:10:21,850 --> 00:10:28,540 The Milky Way is making about one new star every year, and the light from the stars is another example. 102 00:10:28,540 --> 00:10:35,560 The whole nebula. The light from the stars illuminates the residual cloud of gas and dust from which the star formed. 103 00:10:36,130 --> 00:10:40,270 And actually stars turn out to be born, usually in small groups. 104 00:10:40,720 --> 00:10:45,340 Here's the very famous nebula called the Carina Nebula, where you can see if you. 105 00:10:45,620 --> 00:10:50,330 Have good eyesight, that there's several stars being born there at the same time. 106 00:10:51,520 --> 00:10:56,390 Now, however, not all nebulae are about birthplaces of galaxies. 107 00:10:56,420 --> 00:11:01,850 Some of them might be opposite that graveyards. And that is a very famous nebula called the Crab Nebula. 108 00:11:02,180 --> 00:11:07,070 Inside it, there is a remnant of a star that died because it ran out of fuel. 109 00:11:07,310 --> 00:11:11,600 Stars shine because they undergo nuclear reactions in the centres. 110 00:11:11,600 --> 00:11:19,490 These one run out of nuclear fuel and ended up leaving a remnant before called pulsar, which you may be able to see pulsating over there. 111 00:11:20,390 --> 00:11:28,280 Now, here is the only bit of artistic license in this movie where we're going to leave our galaxy and look at it from the top of it. 112 00:11:28,340 --> 00:11:34,310 We cannot do that. But it's a galaxy very similar to the Milky Way. Galaxy is about 50,000 light years across. 113 00:11:34,430 --> 00:11:37,130 So it takes 50,000 years for light to travel. 114 00:11:37,640 --> 00:11:44,180 And so, as you can see, communication with colleagues at the other end of the galaxy is not for the impatient. 115 00:11:44,570 --> 00:11:49,700 Now, here, we're now heading towards the nearest large galaxy, 116 00:11:49,700 --> 00:11:57,620 towards the Andromeda galaxy that you see here has a neighbour called M32, which itself has its own clouds of gas and dust. 117 00:11:57,890 --> 00:12:02,140 And these Galaxy two is making about one new star every year. 118 00:12:02,150 --> 00:12:07,140 So these are Andromeda at a distance of about 2.1 million light years. 119 00:12:07,220 --> 00:12:14,690 Again, not suitable for snappy repartee with extraterrestrials and that we now leave a neighbourhood. 120 00:12:14,690 --> 00:12:17,770 We're going to head to the subject called the Virgo Cluster of Galaxies. 121 00:12:17,780 --> 00:12:22,970 But before we do, that will take a small detour to admire these incredible things that nature has made. 122 00:12:23,420 --> 00:12:30,110 I mean, these objects are enormous. They contain hundreds of billions of stars, and they are truly beautiful and spectacular. 123 00:12:30,110 --> 00:12:36,290 Here is the galaxy that's interacting with a neighbour. And you can see here galaxies are not distributed at random in the universe. 124 00:12:36,530 --> 00:12:40,370 They follow patterns. Here is a very good cluster of galaxies, 125 00:12:40,370 --> 00:12:49,040 a collection of thousands of bright galaxies which lies at a distance of about 30 million light years from us. 126 00:12:49,040 --> 00:12:54,470 And that in the centre of Virgo there's a very famous galaxy here called M87. 127 00:12:54,800 --> 00:12:56,420 This is famous, amongst other reasons, 128 00:12:56,420 --> 00:13:04,100 because it has a very massive supermassive black hole that weighed 2 billion times as much as our sun in the centre. 129 00:13:04,310 --> 00:13:10,160 And this black hole is busy eating material around it and you can see possibly the effects 130 00:13:10,160 --> 00:13:14,960 of the digestion of that material in the form of a small jet that you can see there. 131 00:13:15,410 --> 00:13:23,180 So this is the universe around us and this is what cosmology would like to be able to understand. 132 00:13:28,330 --> 00:13:35,739 A great project. It really takes me back to a days in Durham where Roger could always make things work, but I could break them. 133 00:13:35,740 --> 00:13:38,690 He would fix them now. 134 00:13:38,880 --> 00:13:47,470 So even though there's so many galaxies in the universe, about 100 billion galaxies in the visible universe, each with about 100 billion stars, 135 00:13:47,800 --> 00:13:53,380 we actually now know that the material that makes galaxies and stars and planets and people, 136 00:13:53,620 --> 00:13:56,680 it's actually a very small fraction of what the universe contains. 137 00:13:57,130 --> 00:13:58,780 So what we call ordinary matter, 138 00:13:59,440 --> 00:14:07,900 that is matter made of the ordinary atoms that you can find in the periodic table makes up only about 5% of what the universe contains. 139 00:14:09,290 --> 00:14:12,560 About 25% is dark matter. 140 00:14:12,680 --> 00:14:18,230 That is battery that does not emit light at any wavelength in the electromagnetic spectrum. 141 00:14:18,650 --> 00:14:25,220 And that makes up five times as much matter as a normal matter made of atoms. 142 00:14:25,730 --> 00:14:28,820 But we don't know that the lion's share of the universe is not even matter. 143 00:14:29,510 --> 00:14:33,230 70% of the universe is something that we call that candy. 144 00:14:33,860 --> 00:14:40,519 And even though we've made tremendous progress in addressing some of the questions that I put up on my face, 145 00:14:40,520 --> 00:14:48,980 life slightly balancing state of play in a subject is that we really don't know what is 146 00:14:49,430 --> 00:14:55,130 either of these two components is so even though they make up 95% of matter in the universe, 147 00:14:55,430 --> 00:15:01,580 we're still struggling to understand exactly what these two components are. 148 00:15:02,120 --> 00:15:11,839 So let me tell you briefly about that, KENNEDY, because that is the more mysterious of the two, the one we would really know very little about, 149 00:15:11,840 --> 00:15:15,590 and that we know so little that in a couple of slides I'm about to show you, 150 00:15:15,890 --> 00:15:22,490 I'm going to bring you up to the same level as the experts who get paid to work on the subject. 151 00:15:23,210 --> 00:15:29,060 Before I do that, let me just apologise that I have to do a few antics here. 152 00:15:29,060 --> 00:15:35,940 That's because I have a backache and that. And then when my vegetable, after I talk for 10 minutes at least a good clock to tell me when to stop, 153 00:15:35,940 --> 00:15:43,009 but my vertebra starts compressing a nerve and you have to sit down for a couple of minutes, and then the vertebra moves and then I'm happy again. 154 00:15:43,010 --> 00:15:48,709 But so you just ignore my antics here. And let me tell you then a little bit about that. 155 00:15:48,710 --> 00:15:54,650 KENNEDY So the. Dark energy has to do with a cosmic expansion. 156 00:15:54,950 --> 00:16:04,430 That expansion of the universe was discovered in 1937 by this man in 1929 by rather by this man, Edwin Hubble. 157 00:16:04,670 --> 00:16:08,210 In the days when, as you can see, astronomers were allowed to smoke in their offices. 158 00:16:08,570 --> 00:16:15,640 And even more importantly, they were allowed to have blackboards, which we are no longer allowed, at least not out here. 159 00:16:15,680 --> 00:16:20,720 You are here, right? I should take those views back to that. 160 00:16:21,060 --> 00:16:29,240 But Edwin Hubble Hubble looked at galaxies around us and discovered that with the exception of Andromeda, 161 00:16:29,600 --> 00:16:35,060 all the galaxies are moving away from us with a velocity that is proportional to the distance. 162 00:16:35,480 --> 00:16:40,219 In other words, the farther away a galaxy is, the faster it is moving away from us. 163 00:16:40,220 --> 00:16:48,049 And all galaxies are, with one exception, dropped by that because of the gravitational pull of the Milky Way, it's bringing it back to Earth. 164 00:16:48,050 --> 00:16:53,150 But all other galaxies are moving away from us in this sort of regular pattern. 165 00:16:53,180 --> 00:16:58,850 So what he had discovered was the expansion of the universe. Now, that was in 1929. 166 00:16:59,120 --> 00:17:05,030 Then at the end of last century, other astronomers made a very remarkable discovery, 167 00:17:05,390 --> 00:17:13,130 namely that not only is the universe expanding, but the rate at which it is expanding is increasing with time. 168 00:17:13,280 --> 00:17:17,660 So the expansion is getting faster and faster and faster and faster. 169 00:17:18,080 --> 00:17:26,870 And that is a big surprise because if the universe was just made of matter, then you would expect, as Americans say, gravity sucks. 170 00:17:27,260 --> 00:17:32,150 You would expect gravity to pull the universe back. So the expansion should be slowing down. 171 00:17:32,270 --> 00:17:42,110 Before we had was not there. But in fact, the observations show that contrary to that, the expansion is accelerating. 172 00:17:42,560 --> 00:17:50,360 And that means was interpreted for reasons of describing the minute as implying that the universe is full of something. 173 00:17:50,720 --> 00:17:51,709 And in science, 174 00:17:51,710 --> 00:18:01,310 you always have to be suspicious when you find names that are slightly odd just means that the people who make these names know nothing about it, 175 00:18:01,310 --> 00:18:09,640 and that tenet is the best example of something where the darkness really has to do with our understanding of what this God wanted this, 176 00:18:09,680 --> 00:18:13,550 but in spite of that, what the substance is, rather that in spite of that, 177 00:18:13,700 --> 00:18:22,220 the discovery of the accelerating universe and the Nobel Prize in physics to three colleagues in 2011. 178 00:18:23,470 --> 00:18:25,250 So what is this dark energy? 179 00:18:25,370 --> 00:18:33,490 Well, we don't really know what it is, but it probably has to do with that vacuum energy that I was talking about at the beginning. 180 00:18:33,500 --> 00:18:36,530 And the reason is the following. So imagine two galaxies. 181 00:18:36,530 --> 00:18:41,180 The universe is almost empty that these island universes called galaxies. 182 00:18:41,480 --> 00:18:46,910 Between them, there's nothing. There's a vacuum much better than any vacuum that we can make on earth. 183 00:18:47,330 --> 00:18:55,370 So imagine two galaxies. There's nothing in between. And they are moving apart from one another faster and faster and faster. 184 00:18:55,970 --> 00:18:58,850 So what that means is there is nothing in the nothingness. 185 00:18:58,850 --> 00:19:06,530 There must be something that's pushing these two galaxies, and that something is what we call the dark energy. 186 00:19:06,830 --> 00:19:10,610 So in form of repulsive energy, and because there is nothing in between, 187 00:19:10,610 --> 00:19:15,560 the galaxies surely must have something to do with empty space with the vacuum. 188 00:19:16,040 --> 00:19:24,469 So we think then that whatever the dark energy is, it must have something to do with vacuum energy. 189 00:19:24,470 --> 00:19:28,040 But that's only the sort of hint we're following at present. 190 00:19:28,400 --> 00:19:37,790 That's about it. That's about all the sum total of scientific knowledge in the subject that can see some people who work on dark energy. 191 00:19:38,030 --> 00:19:41,149 So I hope they won't disagree too violently with me. 192 00:19:41,150 --> 00:19:45,860 I mean, there are many other many other avenues that are being pursued. 193 00:19:46,160 --> 00:19:49,430 But I think that summarises where we are now. 194 00:19:49,430 --> 00:19:56,210 We know a lot more about dark matter and which is in fact one of the subjects in which I specialise. 195 00:19:56,330 --> 00:20:02,310 And let me tell you a bit about dark matter now. So for dark matter, we do really have some quite straightforward evidence. 196 00:20:02,690 --> 00:20:05,899 And the eminence comes from various sources, 197 00:20:05,900 --> 00:20:13,550 but the most impressive one has to do with the way in which stars rotate around the centre of the galaxy to which they belong. 198 00:20:14,550 --> 00:20:23,120 So we know since Newton how to understand the rotation of, say, planets around the sun or stars around the centre of the Milky Way. 199 00:20:23,540 --> 00:20:30,140 And there's a very simple formula that Newton discovered 350 years ago, 300 years ago or so, 200 00:20:30,410 --> 00:20:35,390 which describes how stars should be moving around the centre of the galaxy. 201 00:20:35,600 --> 00:20:42,079 And what these law tells us is that if all the material that makes holes the galaxy 202 00:20:42,080 --> 00:20:48,709 together gravitationally is contained in the brightest parts of the galaxy, 203 00:20:48,710 --> 00:20:51,970 then the velocities should be falling off with distance. 204 00:20:52,100 --> 00:20:57,280 That's what simple Newtonian theory predicts. But I was confused about these the other day. 205 00:20:57,290 --> 00:21:00,980 I was in London walking in the streets and I was thinking about this. 206 00:21:01,550 --> 00:21:08,230 Something I couldn't quite understand. And then fortunately, I run into Newton's in self and appears. 207 00:21:08,860 --> 00:21:12,919 He said, Come back and run into me in London. 208 00:21:12,920 --> 00:21:18,740 That's why I have that silly grin, because I was able to understand by talking to Newton here, 209 00:21:19,400 --> 00:21:23,510 he's more than the incarnation what the laws of gravity are all about. 210 00:21:23,510 --> 00:21:27,530 It is new that we look at the most exciting things. They know the job. 211 00:21:28,970 --> 00:21:33,110 It is Newton, a bit older than the one in the picture here. 212 00:21:33,110 --> 00:21:41,089 But nevertheless anyway. And things better than. So the way then we know that our Milky Way is embedded, 213 00:21:41,090 --> 00:21:50,000 swimming in a pool of dark matter is just by observing that the stars rotate much too fast to be held in place by the gravity of the visible matter. 214 00:21:50,480 --> 00:21:56,870 So the stars, the velocity far from falling off, away from the centre, essentially stays constant. 215 00:21:57,230 --> 00:22:04,400 And that means that there must be some other source of gravity other than the gravity that we see in the core, 216 00:22:04,400 --> 00:22:10,010 the gravity that are produced by the material that we see that must be keeping those stars in place. 217 00:22:10,310 --> 00:22:19,820 And that is what we call dark matter. So the way to think of the galaxy is as a pool of light embedded in a large clump of dark matter, 218 00:22:20,150 --> 00:22:26,900 which for reasons I've never really understood, astronomers call that very haloes, and I really don't know why. 219 00:22:26,900 --> 00:22:33,230 Halos. Halos, to me, evokes the saint with the halo of beatitude. 220 00:22:33,500 --> 00:22:39,950 And that's not what astronomers are like. Yet we refer to this objects as dark matter halos now. 221 00:22:40,100 --> 00:22:46,550 So they're really globs of dark matter and they are responsible for keeping galaxies in place. 222 00:22:46,940 --> 00:22:54,440 Now, what is the dark matter clearly is fundamental question in modern physics, and we don't yet know for sure, 223 00:22:54,590 --> 00:23:02,180 but we have a very strong hint that whatever it is, it has something to do with the universe. 224 00:23:02,480 --> 00:23:09,500 And it almost certainly is some elementary particle that was produced when the universe was very young, 225 00:23:10,010 --> 00:23:14,480 but one billionth of a second of one billionth of a second after the Big Bang. 226 00:23:15,230 --> 00:23:27,170 According to theories of particle physics, the universe had cooled enough that a process called symmetry or supersymmetry rather took place. 227 00:23:27,170 --> 00:23:33,590 And I mentioned supersymmetry because it may be in the news in the next year, for reasons I'll tell you in a minute. 228 00:23:33,590 --> 00:23:37,250 So supersymmetry is the new Higgs. I'll tell you more about it in a minute. 229 00:23:37,460 --> 00:23:44,090 But when the universe was about a billionth of a second over, then supersymmetry prevailed. 230 00:23:44,180 --> 00:23:51,080 And as a result of that, elementary particles that would produce, produce in enormous numbers, 231 00:23:51,380 --> 00:23:58,580 that would produce all the gravity needed for dark matter, could have been generated during these period. 232 00:23:59,090 --> 00:24:06,530 And that often goes also by the name of cold, dark matter that Roger mentioned in a very nice introduction. 233 00:24:07,850 --> 00:24:15,709 So now what is the dogmatic? Well, say, I think the working hypothesis of most physicists is that it is some form of elementary particles. 234 00:24:15,710 --> 00:24:21,470 So that is the starting point for the vast majority, not all, but for the vast majority of physicists. 235 00:24:21,800 --> 00:24:25,010 It's an elementary particle, almost certainly from the universe. 236 00:24:25,310 --> 00:24:33,320 And crucially, these supersymmetric particles are very different from the ordinary particles that make up the atoms of which we are made. 237 00:24:33,890 --> 00:24:41,120 So physicists agree with these, but I was actually quite surprised to realise that also politicians seem to know about this. 238 00:24:41,470 --> 00:24:46,070 Now this Angela merkel, somebody has said to her, what if the documents in elementary, tiny elementary particle. 239 00:24:46,400 --> 00:24:50,930 Now it's not surprising because she's, after all, a physicist. 240 00:24:50,930 --> 00:24:56,180 She has a page in physics, solid state physics, but the thing wrong with solid state physics. 241 00:24:58,770 --> 00:25:04,729 Now, I was surprised, though, that this chap also knew. And but that's understandable. 242 00:25:04,730 --> 00:25:08,930 Tony Blair grew up in Durham, about 100 metres from my office. 243 00:25:09,170 --> 00:25:12,590 So he he has every right to know what the dark matter is. 244 00:25:12,590 --> 00:25:25,220 But of course, not all politicians are equally. And what that was a mistake, because, of course, that's what matters comes to him and the poor. 245 00:25:27,920 --> 00:25:32,030 Nevertheless, that at least, yes, it's good to have friends in high places. 246 00:25:32,300 --> 00:25:39,470 He knows this man who's telling him what to talk about. It is that, of course, he learned very, very quickly what took him a while. 247 00:25:39,470 --> 00:25:50,940 He's got to go to that. But finally he's got it. And that's why he's now one of the great champions of of elementary particle dark matter. 248 00:25:50,940 --> 00:26:03,140 And this fellow for good measure anyway. So no, but the reason I show you these pictures is I have a good reason for this, and that is the following. 249 00:26:03,170 --> 00:26:06,170 Politicians work in a strange way. 250 00:26:06,170 --> 00:26:14,690 I've always admired. They they they they have authority. They tell you I'm going to put up the taxes on your pension, and they do it next time. 251 00:26:15,260 --> 00:26:24,020 If you're on a pension, it's smaller than it was before. So they have this authority and this is exactly inimical to the way in which we do science. 252 00:26:24,020 --> 00:26:30,319 So it's not enough for even Angela merkel to tell us that the dark matter is an elementary body in physics. 253 00:26:30,320 --> 00:26:39,160 We got to verify that by evidence. And so that is the key difference, I think, between physics and many other disciplines. 254 00:26:39,170 --> 00:26:42,290 And in physics, we don't take anything for granted. 255 00:26:42,680 --> 00:26:49,310 We search for empirical evidence and the search of dark for dark matter. 256 00:26:49,880 --> 00:26:55,130 And if the experimental physics activity for those of you who've never seen that experimental physics, that's what they look like. 257 00:26:55,550 --> 00:26:59,390 And they're all like this more or less. 258 00:26:59,810 --> 00:27:03,440 And there are actually several ways to look for dark matter. 259 00:27:03,920 --> 00:27:13,160 One, it goes back to what I said a minute ago. I talked about supersymmetry a billionth of a second after after the big bang. 260 00:27:13,280 --> 00:27:18,770 And now, if you recall, when the LHC in Geneva was first opened, 261 00:27:19,160 --> 00:27:26,960 it was billed as being capable of producing conditions that existed in the universe a billionth of a second after the Big Bang. 262 00:27:27,320 --> 00:27:35,030 And that's why many physicists expected that the first interesting result from the LHC would be the discovery of supersymmetry. 263 00:27:35,450 --> 00:27:40,220 Now it didn't happen, but now the LHC has been revamped, its energy increased, 264 00:27:40,340 --> 00:27:47,299 and it may well be that this is the next great big discovery and we'll all hear about it in the news, 265 00:27:47,300 --> 00:27:55,460 because if the LHC discovered supersymmetry, it would amount effectively to making dark matter in the laboratory. 266 00:27:55,700 --> 00:27:57,890 So that was the Higgs. That was last year's news. 267 00:27:58,430 --> 00:28:07,490 And we still haven't found dark matter, but it may well be that we will find it at least evidence through supersymmetry in the next year or two. 268 00:28:07,970 --> 00:28:13,850 Now, that's only one way, but in fact, if the dark matter is what I think it is, this room is full of it. 269 00:28:14,210 --> 00:28:21,680 We're swimming in dark matter. But these particles, and that's why they're different from ordinary matter, don't interact with anything. 270 00:28:21,680 --> 00:28:28,790 They just stream through our bodies at a rate of billions of dark matter particles per second, and they just go through everything. 271 00:28:28,790 --> 00:28:31,010 And that's why they're so difficult to detect. 272 00:28:31,040 --> 00:28:37,520 They produce gravity, but they do not interact with anything, and therefore they do not interact with a detector. 273 00:28:37,790 --> 00:28:43,730 And that's why they're so difficult to detect. However, when I say they don't interact, I don't really mean it. 274 00:28:43,970 --> 00:28:54,200 They do interact, but very, very weakly. And so there are experiments that try to exploit these very weak interactions with with dark matter. 275 00:28:54,200 --> 00:29:07,190 They're usually conducted at the bottom of minds with an experiment very close to where I am place called the Bowlby mind the deep inside. 276 00:29:07,210 --> 00:29:07,610 The mind. 277 00:29:07,830 --> 00:29:18,180 These experiments take place because the earth between the surface and the detector is used as a sieve to filter out all sorts of cosmic rays, 278 00:29:18,180 --> 00:29:24,000 as we call them, particles that rain from outer space onto the earth that would interfere with the experiment. 279 00:29:24,480 --> 00:29:32,270 But here in the bottom of the bogie mind and other places that detectors where they expect occasionally for 280 00:29:32,560 --> 00:29:39,540 one particle of dark matter to hit the nucleus of an atom in the detector and make it wiggle a little bit. 281 00:29:39,690 --> 00:29:45,450 And the experiment consists in trying to detect those wiggles and separate them from the bankrupts. 282 00:29:46,050 --> 00:29:52,050 These guys have given any results yet, but the there has been quite a lot of progress. 283 00:29:52,200 --> 00:29:55,709 The sensitivity of these instruments has increased by many, many, 284 00:29:55,710 --> 00:30:03,210 many orders of magnitude in the last 20 years of 25 years since the first experiment was built, and are now detectors like these all over the world. 285 00:30:03,240 --> 00:30:07,920 Here's a bunch of VIP's visiting and myself visiting the bovey mine. 286 00:30:08,220 --> 00:30:13,560 The reason I like to show this picture is because there were several physicists here, 287 00:30:13,860 --> 00:30:17,240 but there is only one who works in the mine and you can tell who it is. 288 00:30:17,360 --> 00:30:23,550 The only one who is not smiling is working in the mine really is not for the faint hearted. 289 00:30:24,900 --> 00:30:28,530 So we don't yet know what the dark matter is. 290 00:30:28,800 --> 00:30:37,170 But I think this is one of those aspects of my subject where I think we have every reason to 291 00:30:37,170 --> 00:30:42,780 be optimistic that in the next few years we will have the answer to this part of the riddle. 292 00:30:42,990 --> 00:30:48,390 But you've been saying that for the last ten years or so, but I do think that we're close now. 293 00:30:48,600 --> 00:30:57,390 So now why? Why why have I spent all my life working on dark matter that I could see many people here that do the same and they bring some young ones? 294 00:30:58,050 --> 00:31:02,040 Now, why is dark matter so important? Well, obviously, we want to know what the universe is made of. 295 00:31:02,400 --> 00:31:09,990 But that's only one small part of the story. To me, the dark matter is important, not just out of the curiosity about what our universe is made of, 296 00:31:10,380 --> 00:31:18,180 but because of the crucial role that dark matter plays in explaining why the universe looks the way it is. 297 00:31:18,690 --> 00:31:24,060 Because, as I will show you in the next few minutes, it is thanks to the dark matter that we're here. 298 00:31:24,580 --> 00:31:28,409 There was no dark matter. There would be nothing in the universe. 299 00:31:28,410 --> 00:31:29,580 It would be really, really boring. 300 00:31:29,880 --> 00:31:35,700 There would be no galaxies, there would be no stars, there would be no planets, and there would be therefore no people. 301 00:31:35,730 --> 00:31:42,150 So in a sense, I think searching for the data, the dark matter is, in a sense, searching for our own identity. 302 00:31:42,720 --> 00:31:48,060 So the dark matter plays such an important role because it is the gravity of dark 303 00:31:48,060 --> 00:31:52,440 matter that drives the formation of galaxies and other structures in the universe. 304 00:31:53,010 --> 00:31:54,540 So let me tell you a little bit about that, 305 00:31:54,690 --> 00:32:01,200 which is another of these amazing subjects where there's tremendous progress at the workshop I'm attending here, 306 00:32:01,710 --> 00:32:11,370 what a lot of it has to do with building instruments to really look at how this whole process of the formation of structure in the universe unfolded. 307 00:32:11,820 --> 00:32:18,750 Now, if we want to ask the question of where the galaxies come from, we have to go to early times, in fact, very early times indeed. 308 00:32:19,110 --> 00:32:27,270 The story begins when the universe was a decimal point, 35 zeros, and then one that fraction of a second after the Big Bang. 309 00:32:27,600 --> 00:32:31,740 That's when the story of the formation of the structure of the universe begins. 310 00:32:32,100 --> 00:32:40,890 And guess who plays a key role? The dark energy and the reason that dark energy plays a key role is twofold. 311 00:32:41,760 --> 00:32:47,520 We now think that the universe very early on then to the -30 5 seconds after the 312 00:32:47,520 --> 00:32:55,230 Big Bang underwent a fairly dramatic episode because according to this view, 313 00:32:55,890 --> 00:32:58,860 which is the mainstream view in cosmology, when the universe was born, 314 00:32:59,220 --> 00:33:06,660 it had too much of these vacuum energy and it got rid of it by expanding very, very rapidly for a very brief period of time. 315 00:33:07,440 --> 00:33:10,350 This goes by the name of cosmic inflation, 316 00:33:10,770 --> 00:33:19,530 and it is a phenomenon whereby this excess of dark energy that the universe had at the beginning was dissipated by the universe, 317 00:33:19,530 --> 00:33:28,710 expanding very, very rapidly so that it grew from the size of a proton to the size of a football in about ten to the -30 5 seconds. 318 00:33:30,230 --> 00:33:35,000 And this is the role that Kennedy plays in causing inflation. 319 00:33:35,270 --> 00:33:40,340 But that Kennedy is a quantum process because it has to do with matter and antimatter. 320 00:33:40,760 --> 00:33:45,200 And you can see that these vacuum, if it plays a role, it's always fluctuating. 321 00:33:45,680 --> 00:33:55,040 These are called quantum fluctuations. And these flux continuously fluctuating energy of the vacuum goes by the name of quantum fluctuations. 322 00:33:55,370 --> 00:34:03,440 And the proposition that I'm going to make next is that we all come from a quantum fluctuation produce during inflation, 323 00:34:03,770 --> 00:34:11,060 ten to the -30 5 seconds after the big bang. So that is the proposition of modern cosmology. 324 00:34:11,660 --> 00:34:21,140 When these phantom fluctuations did during inflation is to seed the universe with tiny irregularities produced by this continuously fluctuating few. 325 00:34:21,440 --> 00:34:30,950 As the universe expands very rapidly that these fluctuations become imprinted as genuine fluctuations in the energy density of the universe, 326 00:34:31,160 --> 00:34:36,280 such that the universe would be slightly denser in one place, slightly less dense in another place. 327 00:34:36,290 --> 00:34:43,160 And these are tiny, tiny irregularities. And the proposition is that it's where galaxies come from. 328 00:34:43,520 --> 00:34:50,000 So according to inflation theory, galaxies grew out of these tiny quantum fluctuations. 329 00:34:50,580 --> 00:35:02,690 Now so and then therefore but the whole of the structure of the universe goes back to this process of quantum irregularities. 330 00:35:05,280 --> 00:35:12,489 I post here because. If you hear this for the first time, you should be thinking what these bands. 331 00:35:12,490 --> 00:35:16,000 They can leave of your senses. Quantum fluctuations. 332 00:35:16,720 --> 00:35:20,950 You know, these are tiny little things that happen in the microscopic domain, 333 00:35:21,460 --> 00:35:25,270 making a galaxy like the Milky Way with the hundreds of billions of stars. 334 00:35:25,870 --> 00:35:29,320 Well, I will show you evidence for that in a minute. 335 00:35:29,620 --> 00:35:33,249 But let me first illustrate what I'm talking about with this movie, 336 00:35:33,250 --> 00:35:40,930 which is a simulation of a patch of universe 500 billion light years, which was seeded with quantum fluctuations. 337 00:35:41,230 --> 00:35:44,830 The initial stage is the clock. Millions of years was very, very smooth. 338 00:35:45,160 --> 00:35:54,190 And you see here how this sphere in a computer seeded with quantum fluctuations very quickly, only through the action of gravity, 339 00:35:54,190 --> 00:36:00,460 which is the only thing that is included in the simulations, goes from very being very, very smooth to being highly structured. 340 00:36:00,880 --> 00:36:04,900 So there's a hint here from simulations that we may be onto something good. 341 00:36:05,230 --> 00:36:13,840 Nevertheless, I think that if Einstein or the Newton were to walk through his door and heard me say what I just said, 342 00:36:14,230 --> 00:36:21,280 I often wonder what they say, because I say that, for example, even like quantum mechanics, there are long quantum fluctuations. 343 00:36:21,660 --> 00:36:24,980 And Newton, likewise. Newton thought the universe had been there forever. 344 00:36:25,720 --> 00:36:29,140 And so what do they think? Well, I'm sure I know what Einstein would have done. 345 00:36:29,500 --> 00:36:36,100 That's what I instead would have done. And and this is, I think, probably Newton's likely reaction now. 346 00:36:36,280 --> 00:36:42,460 But the point is, going back to the beginning of my thought, the point is that in physics. 347 00:36:43,800 --> 00:36:47,280 Propositions need to be verifiable by experiment. 348 00:36:47,790 --> 00:36:49,980 Now, this, as you will see, is not an easy experiment to do. 349 00:36:50,370 --> 00:36:59,880 But this is why in physics I can turn up in my institute and come up with the most outrageous idea in the world, 350 00:37:00,360 --> 00:37:04,800 and they will still get paid at the end of the month if my outrageous ideas testable. 351 00:37:05,430 --> 00:37:14,309 It doesn't even need to be right. Just needs to be testable. Now it turns out that the proposition I just made that quantum fluctuations at the 352 00:37:14,310 --> 00:37:21,210 origin of structure when amplified through the action of the gravity of dark matter. 353 00:37:21,540 --> 00:37:28,480 That proposition, amazingly, is testable. Now, if you think about it, it's not obvious we should be testable. 354 00:37:28,900 --> 00:37:33,640 But we are very blessed in my subject because. 355 00:37:34,850 --> 00:37:40,910 In my subject, we have a crystal ball, and the crystal ball is a gift that nature has given us. 356 00:37:41,450 --> 00:37:47,420 And it is to do with the fact that light travels only at a given speed. 357 00:37:47,780 --> 00:37:51,500 Light travels at a speed of 300 kilometres per second. 358 00:37:52,130 --> 00:38:04,010 And what that means is that as we look so, for example, so that light emitted from an object which is far away from us takes some time to get to us. 359 00:38:04,460 --> 00:38:09,350 And then therefore it reflects the conditions that prevailed when the light was submitted. 360 00:38:09,800 --> 00:38:15,470 So when we look at the sun, for example, we realise you can do in Oxford, not in Durham, but in Oxford you can. 361 00:38:16,160 --> 00:38:24,620 You don't see the sun as it is now. You see the sun as it was 8 minutes ago because that's how long it took for the light from the sun to get to us. 362 00:38:24,890 --> 00:38:27,290 And that's because light travels through finite speed. 363 00:38:27,620 --> 00:38:34,730 So the farther away an object is, the longer its life has been travelling and the farther into the past that we can see. 364 00:38:36,170 --> 00:38:44,479 Wow. So the first light that we can see, in fact, tells us about conditions that prevail very early on in the universe. 365 00:38:44,480 --> 00:38:52,790 In the universe was very hot. And throughout its 13.8 billion years of existence, it's been expanding cooling. 366 00:38:52,790 --> 00:38:58,450 As it does so, the early universe was actually very foggy because matter was broken up into particles. 367 00:38:58,730 --> 00:39:07,250 So light kept colliding with particles bouncing around and that created the fog of the early universe. 368 00:39:07,250 --> 00:39:14,180 But when the universe was 350,000 years old, which is the human equivalent of one day in the life of a human. 369 00:39:14,540 --> 00:39:20,869 So when the universe was about in human terms, one day old, 350,000 years after the big bang, 370 00:39:20,870 --> 00:39:26,150 the fog of the Big Bang lifted because the first atoms in the universe formed. 371 00:39:26,510 --> 00:39:35,450 And so these collisions of particles of light with particles of matter stopped, the fog of the big bang lifted and light was emitted. 372 00:39:35,780 --> 00:39:41,090 And that light has been propagating from us since that early time. 373 00:39:41,990 --> 00:39:49,460 These photos of light emitted at that time have been travelling freely throughout the entire cosmic history. 374 00:39:49,850 --> 00:39:59,660 And amazingly, they were discovered in 19 5064 by these two gentlemen, Arno Penzias and Bob Wilson, 375 00:40:00,110 --> 00:40:09,200 who accidentally make many of the great discoveries of science, stumbled upon these radiation that seem to be coming from everywhere. 376 00:40:09,650 --> 00:40:15,170 And that was very, very cold at a temperature of only 2.7 Kelvin, 377 00:40:15,170 --> 00:40:22,909 2.7 degrees above absolute zero because the universe is so old that this radiation has cooled down to these very low temperatures. 378 00:40:22,910 --> 00:40:25,910 They discovered it accidentally. They were looking for that. 379 00:40:26,060 --> 00:40:29,930 They were interested in trying to find that radio emission from the sun. 380 00:40:30,290 --> 00:40:36,589 And this was a known one the background and on a where's this a beautiful study that I don't have time to tell you. 381 00:40:36,590 --> 00:40:42,080 But they were completely unaware of this until accidentally they heard that two, 382 00:40:42,350 --> 00:40:47,149 three people in Princeton, they were in Bell Labs just a few miles from Princeton, 383 00:40:47,150 --> 00:40:57,770 three people in Princeton who were Bob Dickey, Jean Peebles and David Wilkinson, where actually who knew about this radiation were looking for it. 384 00:40:58,130 --> 00:41:07,040 And it was in an aeroplane journey that the news were spread and they had actually stumbled upon the evidence for the Big Bang. 385 00:41:07,550 --> 00:41:11,960 So we have had evidence for the Big Bang Theory since the 1960s. 386 00:41:12,260 --> 00:41:14,150 But according to inflation, 387 00:41:14,630 --> 00:41:22,580 this early universe was seeded with these momentum fluctuations and these quantum fluctuations would propagate during the foggy phase, 388 00:41:22,790 --> 00:41:25,370 but they would still be there when the radiation emitted. 389 00:41:25,970 --> 00:41:34,190 So according to the theory of inflation, we should see in the radiation from the from the radiation from the Big Bang, 390 00:41:34,190 --> 00:41:36,290 which it's called the microwave background radiation, 391 00:41:36,290 --> 00:41:43,850 because it's seen in the form of microwaves today in that radiation, which is the evidence for these quantum fluctuations. 392 00:41:44,290 --> 00:41:46,610 And what would they look like? Well, 393 00:41:46,910 --> 00:41:55,010 it turns out one can calculate that using the laws of physics and the evidence for these small fluctuations should be 394 00:41:55,250 --> 00:42:02,660 labelled patches where of cold and hot spots in the temperature of these relic radiation left over from the big bang. 395 00:42:03,080 --> 00:42:10,879 So if inflation happens and if quantum fluctuations seeded the universe with small fluctuations, 396 00:42:10,880 --> 00:42:15,470 they should be reflected in the temperature of the radiation. 397 00:42:15,860 --> 00:42:21,409 And the physicists can make predictions that forget that not to ignore the technical details, 398 00:42:21,410 --> 00:42:26,870 but they can make predictions for exactly what this pattern of cold and hot spots should look like. 399 00:42:27,140 --> 00:42:30,590 And the reason I show you these is just to say that it is complicated. 400 00:42:30,590 --> 00:42:37,640 It's not something. It has a signature in it. Well, so the in 1992. 401 00:42:39,120 --> 00:42:43,770 Nasser launched a satellite called Kobe, the Kobe back of Explorer. 402 00:42:44,370 --> 00:42:54,720 And this is what Kobe saw. So what you see here is a map of the temperature of this radiation leftover from the Big Bang, 403 00:42:54,960 --> 00:43:00,400 radiation that's been travelling freely until it is detected in a satellite. 404 00:43:00,960 --> 00:43:04,830 And this a map of the temperature of that radiation. 405 00:43:04,830 --> 00:43:13,350 And as you can see here, it's not smooth. It has spots, hot and cold spots, exactly what the doctor ordered. 406 00:43:13,740 --> 00:43:19,710 So much so that these media, these discovery made headline news all over the world. 407 00:43:20,400 --> 00:43:23,570 This was the front cover of the Independent in the days. 408 00:43:23,580 --> 00:43:30,270 If you remember those of you who are of a certain age where the newspapers were still reporting on science in the front page, 409 00:43:30,270 --> 00:43:33,870 that did happen is very dense, I must say. 410 00:43:34,260 --> 00:43:38,580 I'm embarrassed to say this, but I made a contribution to this. 411 00:43:39,550 --> 00:43:46,110 That was the best thing for posterity here in the Independent. 412 00:43:46,500 --> 00:43:51,630 Those of you in the front row could see that. Carlos Frank, an astronomer at Durham University, said yesterday. 413 00:43:51,930 --> 00:44:03,450 Oh, wow. So this is my great contribution to astrophysics and I think my wife sitting here. 414 00:44:03,450 --> 00:44:07,440 So hopefully she put that on my epitaph. But yeah, it really was. 415 00:44:07,590 --> 00:44:10,040 It really was a wild moment. I couldn't believe this. 416 00:44:10,590 --> 00:44:16,950 Now, I must say, though, that one reason for that is this was, as you can see here, April, where you can't anymore. 417 00:44:16,950 --> 00:44:22,230 But it was 22nd of April of 24th of April of 1992. 418 00:44:22,650 --> 00:44:29,370 Now, this was Nasser. Nasser had embargoed the news until midnight Washington time, which happens to be 6 a.m. 419 00:44:29,370 --> 00:44:35,070 Durham time phone rings at 6ami pick it up and I have this American reporter saying to me, 420 00:44:35,250 --> 00:44:39,930 Hey, Dr. Frank, we just discovered the temperature fluctuations in the microwave background. 421 00:44:39,960 --> 00:44:41,640 What did you say at 6 a.m.? Wow. 422 00:44:41,940 --> 00:44:52,200 And anyway, there's more to that story, but that for another time, that that discovery earned George Smoot a Nobel Prize in physics in 2006. 423 00:44:52,890 --> 00:45:01,170 This radiation has been remeasured with greater resolution a decade later by another great satellite W by the W, 424 00:45:01,170 --> 00:45:02,940 by the way, stands for David Wilkinson, 425 00:45:02,940 --> 00:45:11,070 one of the three people I mentioned a minute ago in Princeton who died just before the instrument hit detector he did develop was deployed. 426 00:45:11,640 --> 00:45:14,640 And you can see the same patterns. But now we've been in resolution. 427 00:45:14,880 --> 00:45:22,260 And then, of course, the Europeans caught up a decade later with their own mission called Planck wage increase, 428 00:45:22,260 --> 00:45:31,229 the resolution and the sensitivity tremendously. And so this is now what we know about the microwave background. 429 00:45:31,230 --> 00:45:38,309 Radiation is the state of the art now. So these are the predictions about what the temperature that I show you, this plot. 430 00:45:38,310 --> 00:45:48,720 I again, I don't want to go into the technical details, but what it is, is just it tells us what the pattern of hot spot should look like. 431 00:45:49,080 --> 00:45:59,250 And as a function of the angle of the sky. The point I want to make is firstly that this theory was some of the theoretical predictions based 432 00:45:59,250 --> 00:46:07,409 on inflation and based on the idea of cold dark matter where published in 1982 by Jean Peebles, 433 00:46:07,410 --> 00:46:12,900 they would work also very extensively here by Georgia staff you and the bond and 434 00:46:13,440 --> 00:46:18,180 these were predictions that were made in the 1980s based on the idea of inflation, 435 00:46:18,450 --> 00:46:24,450 based on the idea of quantum fluctuations and based on the idea of dark matter and of cold, dark matter. 436 00:46:24,750 --> 00:46:29,190 And this is what the corresponding plot from Planck looks like. 437 00:46:29,700 --> 00:46:33,810 And you can see here, this is just from earlier this year. 438 00:46:34,650 --> 00:46:41,820 This to me when I look at I've looked at this plot dozens of time, more hundreds of times and. 439 00:46:43,540 --> 00:46:48,790 It leaves me speechless because it really is astonishing. 440 00:46:49,760 --> 00:46:56,390 What you can see here in my mind is one of the great triumphs of human civilisation. 441 00:46:56,420 --> 00:47:03,260 Why? Well, because what you see here is some theoretical prediction shown here by the Green Line, 442 00:47:03,920 --> 00:47:10,520 made by physicists using the tools of mathematics and using the laws of physics, 443 00:47:10,820 --> 00:47:17,930 extrapolated from Earth down to our own, the beginning of our own universe. 444 00:47:17,960 --> 00:47:20,830 So it's a theory about the beginning of our own universe. 445 00:47:20,840 --> 00:47:29,090 So the fact that for whatever reason you humans have evolved to have the ability to make these theories is already astonishing. 446 00:47:29,540 --> 00:47:34,580 But the fact that these same creatures are capable of building machines that they can 447 00:47:34,850 --> 00:47:41,210 launch out of the planet and measure these tiny signals because they are really tiny. 448 00:47:41,510 --> 00:47:45,860 That one part in ten to the five shown here by the red dots is incredible. 449 00:47:45,890 --> 00:47:47,510 It really is quite amazing. 450 00:47:47,870 --> 00:47:56,209 So I think the first time a plot like these was shown to an audience of astronomers, an early version of this, there was a standing ovation, ovations. 451 00:47:56,210 --> 00:48:06,680 The only time in my life that I've seen that. And it is to me, really an enormous triumph, not just of cosmology, not just of physics, 452 00:48:07,130 --> 00:48:14,990 not just of science, but I think of human creativity and human capabilities right now. 453 00:48:15,350 --> 00:48:23,210 So I'm nearly done. And but even though we're only 350,000 years in from the beginning, 454 00:48:23,450 --> 00:48:31,670 the rest is much easier because the rest is to work out how these small perturbations that we see in the microwave background radiation, 455 00:48:32,030 --> 00:48:36,740 how they evolve to produce the galaxies that we see in the universe today. 456 00:48:37,040 --> 00:48:40,130 That's a much easier project, no problem. 457 00:48:40,430 --> 00:48:48,080 Because we can deploy big computers to solve the equations of physics as they apply to the expanding universe. 458 00:48:48,320 --> 00:48:53,660 That's something that we know how to do quite well. So let me just finish off with a few movies. 459 00:48:53,960 --> 00:49:01,310 Here's a movie that shows from quantum fluctuations how the halo of our own Milky Way galaxy would have formed. 460 00:49:01,730 --> 00:49:04,400 So here's the clock ticking again in billions of years. 461 00:49:05,090 --> 00:49:10,700 And it was very smooth, really times that which is this quantum fluctuations that we're talking about. 462 00:49:11,030 --> 00:49:16,819 This is the dark matter called dark matter. How it shows you how sky the gravity of the cold. 463 00:49:16,820 --> 00:49:24,770 Dark matter amplifies these small quantum fluctuations, producing at first a very intricate pattern. 464 00:49:25,550 --> 00:49:28,940 It's a small version of something that cosmologists call the cosmic web. 465 00:49:29,510 --> 00:49:35,180 You see all these lumps? This is just where gravity has amplified these quantum fluctuations and that these lumps 466 00:49:35,630 --> 00:49:40,400 arrange themselves in a way we understand into mathematically into these filaments. 467 00:49:40,730 --> 00:49:44,390 And then it's just gravity that attracts one clump for the other. 468 00:49:44,600 --> 00:49:49,100 When they collide, they fuse together, building larger and larger structures. 469 00:49:49,130 --> 00:49:52,790 So this is known in the trade. 470 00:49:53,090 --> 00:49:56,989 It's hierarchical clustering and describes the way in which a universe is made 471 00:49:56,990 --> 00:50:01,910 of called dark matter would have resulted in a halo like that of the Milky Way. 472 00:50:03,170 --> 00:50:07,850 Now that's just dark matter. Here's another view of dark matter now at the present day. 473 00:50:08,210 --> 00:50:14,040 So here we're just cruising through the universe today. 474 00:50:14,060 --> 00:50:17,570 We had the dark matter glasses, and we were able to travel very, very, very fast. 475 00:50:18,320 --> 00:50:26,540 We would see the universe is seeded with these halos everywhere, which is where we expect inside these halos. 476 00:50:26,780 --> 00:50:33,260 We expect ordinary matter in really times made of gas to collapse due to the gravity 477 00:50:33,530 --> 00:50:40,040 of the dark matter halos and then fragment into stars and produce visible galaxies. 478 00:50:40,400 --> 00:50:45,680 Now all that's going into these simulations is inflation, quantum fluctuations. 479 00:50:45,980 --> 00:50:51,080 And for the dark matter problem only. The only thing we need is relativity. 480 00:50:51,080 --> 00:50:55,309 Because the universe expands and gives gravitational physics, which is physics. 481 00:50:55,310 --> 00:51:07,430 We've understood now for a long, long time, for over 100 years in the last year or so, efforts going back decades have begun to bear fruit, 482 00:51:07,760 --> 00:51:11,420 where we now try to simulate just the evolution of the dark matter, 483 00:51:11,630 --> 00:51:17,270 but also the evolution of the ordinary material that makes the stars and the galaxies. 484 00:51:17,300 --> 00:51:29,420 So this comes from a project I was just published earlier this year called The Eagle Simulations with Eagle stands for Forget Evolution, 485 00:51:29,420 --> 00:51:36,560 An Assembly of Galaxies and the Environment. And it shows the evolution of the various components of the universe. 486 00:51:37,160 --> 00:51:42,820 Yeah. Here you see. First up, dark matter just as before evolving. 487 00:51:43,190 --> 00:51:46,490 Here's the clock, which is clearly visible, but it doesn't really matter. It's very early times. 488 00:51:46,850 --> 00:51:56,980 What we see here is quantum fluctuations. And how they cause the dark matter to to assemble into these filaments. 489 00:51:57,250 --> 00:52:00,880 But now we're going to change to gas. So what you see here, we're zooming into one object. 490 00:52:01,150 --> 00:52:06,070 And now we're looking at gas. Not a dark matter anymore. And here, this is an object of interest. 491 00:52:06,370 --> 00:52:15,010 There was a quantum fluctuation there. And that is now, as you can see, as time goes by, producing something reminiscent of a galaxy. 492 00:52:15,040 --> 00:52:20,200 So here by now, the universe is about 5 billion years old. 493 00:52:20,530 --> 00:52:23,559 Now we see stars. These are now the stars in the simulation. 494 00:52:23,560 --> 00:52:26,600 That's what came out of that process. 495 00:52:26,600 --> 00:52:33,490 And we go back to gas and we zoom further in. The universe is now about 8 billion years old. 496 00:52:33,670 --> 00:52:38,410 And we're looking at the gas again. And this is what came out. 497 00:52:39,400 --> 00:52:47,020 Just from the loss of physics, assuming an initial state characterised, as you said, by quantum fluctuations. 498 00:52:48,350 --> 00:52:51,350 So here's the guys. Here the stock. 499 00:52:53,190 --> 00:53:00,719 And that is a volume of cosmological volume. Now zoom out again and see if we can make a computer. 500 00:53:00,720 --> 00:53:04,690 Not just one galaxy, but many. And I. 501 00:53:06,910 --> 00:53:10,180 Some it's like to be slightly mischievous. So I played a trick. 502 00:53:11,320 --> 00:53:14,350 On some colleagues of my Durham minor. Durham. 503 00:53:14,350 --> 00:53:19,870 I won't mention who they are. I showed them this picture and they say these are observer observational astronomers. 504 00:53:20,260 --> 00:53:23,470 Several of them here. I show them this picture. I said, What do you think? 505 00:53:24,430 --> 00:53:29,770 Do you recognise these galaxies? I can't remember which catalogue I got these from which catalogue they use. 506 00:53:30,070 --> 00:53:34,510 Do you know which catalogue? Well, I got all sorts of interesting subjects. 507 00:53:34,630 --> 00:53:39,400 The Hubble Atlas surely, said two of them. Now they came out of a computer. 508 00:53:39,910 --> 00:53:48,970 These is what we can do in computers today in following this whole structure, this whole. 509 00:53:50,270 --> 00:53:59,600 Building that I described to you this evening. So let me then finish off with a summary so I can tell you really a story about nothing. 510 00:53:59,840 --> 00:54:03,560 I'm sure it doesn't feel now that I've been talking about nothing, I've been talking about quite a lot. 511 00:54:03,950 --> 00:54:07,550 But the story I told you is essentially very simple. 512 00:54:07,940 --> 00:54:18,620 It goes back to the very early universe, been to the -30 5 seconds after the big bang, when due to the presence of the vacuum energy, 513 00:54:18,890 --> 00:54:26,000 the universe expanded very rapidly and this expansion cause more fractures, which we know as quantum fluctuations, 514 00:54:26,360 --> 00:54:32,689 whose presence is detected directly in the temperature of the microwave background radiation. 515 00:54:32,690 --> 00:54:37,790 The heat left over from the Big Bang 350,000 years after the Big Bang. 516 00:54:38,060 --> 00:54:45,440 And it is the amplification of these fluctuations through the gravity of dark matter that produces the universe, which we see today. 517 00:54:46,190 --> 00:54:49,670 So is this is this the end of the story? 518 00:54:50,150 --> 00:54:57,470 Well, no, it's only I hate to say the end of the beginning, but it is only the end of the first part, 519 00:54:57,920 --> 00:55:02,630 because in reality, we don't know what is the dark matter. 520 00:55:03,410 --> 00:55:10,309 I hope it is what I spend all my life working on, but there's no guarantee that it is that we're still to discover what the dark. 521 00:55:10,310 --> 00:55:15,000 But it is. It's a big open question. The subject. That? 522 00:55:15,000 --> 00:55:22,920 Kennedy. I often say that if I lived my life expectancy and my age, I should be around to see this question answered. 523 00:55:22,920 --> 00:55:25,110 But I doubt that will be around to see these one. And. 524 00:55:25,290 --> 00:55:31,649 That's a really, really tough question because we don't even really know how to start trying to address this. 525 00:55:31,650 --> 00:55:33,990 But there are many instruments that are being built, 526 00:55:34,830 --> 00:55:42,710 often at great cost to you taxpayers to try and characterise what is causing these accelerated expansion. 527 00:55:42,720 --> 00:55:51,420 But as of now we know very little about it. And of course the key question is how did the universe begin in the first place? 528 00:55:52,050 --> 00:56:02,130 So let me then conclude, I think I hope I've shown that there's been enormous progress in this subject over the past 30 years of so. 529 00:56:02,460 --> 00:56:08,100 But in my opinion, I think they still owe this is to say the best is still to come. 530 00:56:08,400 --> 00:56:13,350 And I think it's not I must be feeling depressed that day, but I think the best is still to come. 531 00:56:13,680 --> 00:56:24,780 And so look out for the discovery of the dark matter and which I think will give another big piece of evidence for this whole picture. 532 00:56:25,230 --> 00:56:28,680 And but don't hold your breath for that. I get it. I'll stop here.