1 00:00:00,00 --> 00:00:14,82 Interviewer: I will ask a lot of questions, but I prefer it to be like a conversation, so interrupt me if you like. 2 00:00:14,82 --> 00:00:16,13 Juan Maldacena: Right, good. 3 00:00:16,13 --> 00:00:18,15 Interviewer: The first thing, can you introduce yourself? 4 00:00:18,15 --> 00:00:22,97 Juan Maldacena: Yeah, I'm Juan Maldacena, I'm the Carl Feinberg professor here at the Institute for Advanced Study. 5 00:00:22,97 --> 00:00:28,83 Interviewer: What exactly is your field of research? 6 00:00:28,83 --> 00:00:33,54 Juan Maldacena: My field of research is in trying to understand the fundamental laws of nature, 7 00:00:33,54 --> 00:00:39,29 trying to develop theories that connect space-time and quantum mechanics, 8 00:00:39,29 --> 00:00:43,23 and the main objective is to understand the beginning of the Big Bang. 9 00:00:43,23 --> 00:00:48,08 Interviewer: Well, that's a big question. 10 00:00:48,08 --> 00:00:48,48 Juan Maldacena: Yeah. 11 00:00:48,48 --> 00:00:50,88 Interviewer: Did you say the laws of nature? 12 00:00:50,88 --> 00:00:56,47 Juan Maldacena: Yeah. Physics is about studying the laws of nature, so how nature works. 13 00:00:56,87 --> 00:00:59,77 Through the years we've learned a lot about how nature works, 14 00:01:00,48 --> 00:01:04,16 and currently we have theories that are incredibly successful. 15 00:01:05,38 --> 00:01:08,65 One of the theories is the theory that describes gravity. 16 00:01:08,65 --> 00:01:12,91 It was originally developed by Newton, and then improved by Einstein. 17 00:01:12,91 --> 00:01:19,23 Einstein gave us the current equations that govern the behavior of space-time. 18 00:01:19,23 --> 00:01:23,24 We'll discuss perhaps a bit more about what space-time is made of, 19 00:01:23,24 --> 00:01:29,64 or what the theory of Einstein tells us about space-time. That's one very successful theory. 20 00:01:29,95 --> 00:01:39,83 It explained things like the expansion of the universe, the formation of black holes.. 21 00:01:36,04 --> 00:01:39,66 Its phenomena that before the theory was introduced, were .. 22 00:01:39,83 --> 00:01:54,51 People didn't even think about them. On the other hand we the whole set of theories that describe matter, 23 00:01:54,78 --> 00:01:57,04 the behavior of matter and the structure of matter. 24 00:01:57,04 --> 00:01:57,21 These theories were rational, 25 00:01:57,21 --> 00:02:02,96 especially rational quantum mechanical study being developed in the beginning of the 20th century. 26 00:02:03,98 --> 00:02:08,84 The quantum is very important for the description of matter. 27 00:02:08,84 --> 00:02:15,39 It's what keeps matter stable and prevents it from collapsing. Prevents atoms from collapsing, and so on. 28 00:02:15,39 --> 00:02:20,77 This theory, well, it was further developed through the 20th century 29 00:02:20,77 --> 00:02:26,71 and it's now come to what we call the standard model of particle physics. 30 00:02:26,71 --> 00:02:28,02 Interviewer: Particle physics. 31 00:02:28,02 --> 00:02:33,75 Juan Maldacena: It's basically the basic structures, the basic constituents of matter. 32 00:02:33,75 --> 00:02:40,54 Matter is made out of little, small particles that behave according to the so-called quantum mechanics. 33 00:02:42,89 --> 00:02:46,88 What is remarkable is that this list of constituents is very small. 34 00:02:46,88 --> 00:02:51,59 So a very small number of particles make up all the matter that we see. 35 00:02:51,59 --> 00:02:58,66 Interviewer: Really? So everything is built up from just a small number of particles? 36 00:02:58,66 --> 00:03:00,92 Juan Maldacena: Yes, small number of kinds of particles. 37 00:03:01,37 --> 00:03:08,46 We have the particles, the electron is one of them, and then we have the particles that make up the nuclei, 38 00:03:09,65 --> 00:03:13,58 the nuclei of the atom. Within the nuclei are some particles called quarks, but they are small, little particles. 39 00:03:14,05 --> 00:03:20,59 For most of matter they are made out of just two kinds, so-called up and down quark. 40 00:03:21,15 --> 00:03:28,62 Then there are some particles that mediate the forces within them. The photon, electromagnetic waves, and so on. 41 00:03:28,62 --> 00:03:31,59 Then the weak force and the strong force. 42 00:03:32,61 --> 00:03:39,76 The strong force keeps the nucleus together, and with these particles and these forces we can describe all of matter. 43 00:03:39,76 --> 00:03:42,45 Interviewer: You know that, or you think so? 44 00:03:42,45 --> 00:03:46,03 Juan Maldacena: No, well we know it experimentally, 45 00:03:46,03 --> 00:03:56,9 and the latest experiment was the experiment in the large hydro collider, which discovered the so-called Higgs boson, 46 00:03:56,9 --> 00:03:59,83 which was one of the missing particles in the standard model. 47 00:04:00,35 --> 00:04:03,91 Now we have whole set of particles that describes everything. 48 00:04:04,32 --> 00:04:08,83 I briefly told you about the particles that make up most all named matter, 49 00:04:08,83 --> 00:04:17,58 but there are other unstable particles which are similar, but the structure gets replicated a few times, 50 00:04:17,58 --> 00:04:25,72 and while so now we have a complete set of particles with a logically consistent theory that uses the structure of 51 00:04:25,91 --> 00:04:28,35 something called relativistic quantum mechanics. 52 00:04:28,35 --> 00:04:30,93 [crosstalk 00:04:30] Relativistic quantum mechanics, 53 00:04:30,93 --> 00:04:37,87 there's quantum mechanics plus the principle of special relativity. We can discuss perhaps special relativity a little 54 00:04:37,93 --> 00:04:44,84 more. Let me discuss perhaps these theories a little more. 55 00:04:44,84 --> 00:04:45,38 Interviewer: Yes, that's okay. 56 00:04:45,38 --> 00:04:51,26 Juan Maldacena: Then I can go on into discussing perhaps the more current issues. 57 00:04:53,62 --> 00:04:58,9 First, well we have these notions of space and time. Right? 58 00:04:59,41 --> 00:05:09,99 In principle space and time seem totally disconnected from each other.. 59 00:05:02,88 --> 00:05:09,8 The very intuitive notion of space, while time looks a little more mysterious to us, and a bit .. 60 00:05:09,99 --> 00:05:12,6 Certainly different from space. 61 00:05:12,74 --> 00:05:18,79 The first point I'd like to explain is why physicists talk about space-time, why they put these two words together. 62 00:05:18,79 --> 00:05:25,00 Why don't they talk about space temperature, space I don't know. Price of [solar 00:05:27] or whatever. 63 00:05:25,00 --> 00:05:36,77 They talk about these two things because the way you perceive time depends on how you are moving through space. If you 64 00:05:36,77 --> 00:05:42,16 have two observers moving relative to each other, the two observers perceive time differently. 65 00:05:44,52 --> 00:05:48,07 If you have a clock here, another clock that is moving, 66 00:05:48,77 --> 00:05:54,62 the second clock will appear to this observer as moving slower than the clock here that's at rest. 67 00:05:54,96 --> 00:05:58,26 The other observer will see the other clock also moving slower. 68 00:05:58,26 --> 00:06:04,04 This can happen because space and time sort of get mixed by motion. 69 00:06:06,87 --> 00:06:12,42 This is the consequence of a principle, which is the principle that light, 70 00:06:13,00 --> 00:06:19,1 the speed of light is constant for these two observers. This is something that is not totally intuitive. 71 00:06:20,47 --> 00:06:25,59 You have one observer that is stationary and you have a light beam that travels this way, 72 00:06:25,96 --> 00:06:29,8 and you have another observer that moves in this direction, naively, 73 00:06:30,25 --> 00:06:34,21 according to your intuition you will expect that this observer should see the light moving slower. Right? 74 00:06:35,73 --> 00:06:41,26 If instead of talking about the light beam we were talking about the train, that would be the case. 75 00:06:42,65 --> 00:06:50,95 But it turns out that experimentally the speed of light is constant, so it is the same for all observers. 76 00:06:50,95 --> 00:06:53,38 Interviewer: Oh really, so compared to the train? 77 00:06:53,38 --> 00:07:00,89 Juan Maldacena: Yes, so if instead of a train we had a beam of light, the two observers, 78 00:07:00,89 --> 00:07:12,29 one is stationary the other is moving, both would see the light going at the same speed,.. 79 00:07:04,57 --> 00:07:12,14 so the light would be moving this way .. This happens because the rate of .. 80 00:07:12,59 --> 00:07:16,59 How time and space are perceived by the two observers are different. 81 00:07:16,89 --> 00:07:22,9 The price you have to pay for this constancy of the speed of light is that time is now relative. 82 00:07:22,9 --> 00:07:28,9 In the theory of relativity the speed of light is absolute, but time is relative. 83 00:07:28,9 --> 00:07:32,1 Time is relative to who's measuring it. 84 00:07:32,1 --> 00:07:45,41 Interviewer: I can try to understand what you are saying. What I hear is that you say the speed of light is constant. 85 00:07:46,49 --> 00:07:52,93 So time is not constant. 86 00:07:52,93 --> 00:07:54,72 Juan Maldacena: Right, time is relative. 87 00:07:55,23 --> 00:08:03,83 The flow of time depends on how you are moving through space-time, so it's similar to let's say space, right? 88 00:08:03,83 --> 00:08:11,26 So we are standing in space, there is some direction we call forward and some direction we call go right. 89 00:08:11,26 --> 00:08:15,17 But if you have another person who's looking in a different direction what's forward to him 90 00:08:15,17 --> 00:08:21,88 and what's to the right is different. So it's exactly the same but for two moving observers. 91 00:08:21,88 --> 00:08:28,25 You have two moving observers but one calls time and space is different from what the other calls time and space. 92 00:08:29,07 --> 00:08:37,34 That's why is more convenient to think about space-time as something that's both time and space, 93 00:08:37,59 --> 00:08:41,69 and that thing is the same for both. 94 00:08:41,69 --> 00:08:44,01 What one calls time and space is different, 95 00:08:44,02 --> 00:08:52,61 but space-time is the same. It's the universal structure in which particles move. 96 00:08:57,74 --> 00:09:05,06 The laws of physics have to have this symmetry of the constancy of speed of light 97 00:09:05,61 --> 00:09:09,8 and the fact that the laws of physics should be independent of how you're moving. 98 00:09:09,91 --> 00:09:15,48 When you combine quantum mechanics and this principle of special relativity, 99 00:09:15,48 --> 00:09:17,69 you get the modern theory of quantum physics. 100 00:09:17,69 --> 00:09:21,49 Well you get the structure, which is called quantum [field 00:09:21] theory, 101 00:09:21,49 --> 00:09:28,04 and used in special cases of the structure, putting in which particles you have and the interactions and so on. 102 00:09:28,05 --> 00:09:32,5 You get the models for particle physics and they are incredibly successful 103 00:09:32,5 --> 00:09:46,78 and they describe all the experiments that you can do.. 104 00:09:36,46 --> 00:09:46,53 Interviewer: In the beginning you raised the big question, how did the universe .. 105 00:09:46,78 --> 00:09:52,44 Juan Maldacena: Let me first say a few words about general relativity. 106 00:09:56,5 --> 00:10:02,9 According to our intuition, so space is sort of absolute and there is some [inaudible 00:10:03] 107 00:10:02,9 --> 00:10:08,12 in space where particles move and objects move. 108 00:10:09,09 --> 00:10:14,36 That's probably the theory of [mutant 00:10:13] we learned in school, that planets move and so on. 109 00:10:14,36 --> 00:10:20,34 They are moving in some space that was preexisting and it's not affected at all by the motion of these planets. 110 00:10:20,34 --> 00:10:29,11 But in the theory of [inaudible 00:10:25] what Einstein postulates is that space or space 111 00:10:29,11 --> 00:10:33,85 and time because they have to come together because of the principle of special relativity. 112 00:10:33,85 --> 00:10:42,67 They are actually structured that is dynamic because it can be bent by the presence of matter. He further says that the 113 00:10:42,67 --> 00:10:54,46 force of gravity is due to this bend in our space-time. This is a new, very interesting conceptual idea. 114 00:10:54,72 --> 00:11:01,03 Again, it describes gravity as we see it, and it describes deviations from Newton's gravity. 115 00:11:01,03 --> 00:11:09,7 It describes new things that were not known at the time of Einstein, like the expansion of the universe, 116 00:11:09,71 --> 00:11:13,24 the formation of black holes in extreme circumstances. 117 00:11:13,24 --> 00:11:20,82 Well, some of it's predictions are have now been confirmed, like the discovery of gravity waves, very recently, 118 00:11:20,82 --> 00:11:23,27 just a week ago it was announced. 119 00:11:23,27 --> 00:11:25,44 Interviewer: Yeah, I saw that, were you excited about it. 120 00:11:25,44 --> 00:11:28,58 Juan Maldacena: Yeah, that's really exciting, very interesting. 121 00:11:28,58 --> 00:11:33,92 Interviewer: Did you know about that they were going to announce this? 122 00:11:33,92 --> 00:11:37,24 Juan Maldacena: Yeah, there were rumors that they were going to announce it. 123 00:11:37,24 --> 00:11:42,58 Of course the experiment had been going for a couple of decades. 124 00:11:42,58 --> 00:11:45,25 Interviewer: For a couple of billion years. 125 00:11:45,25 --> 00:11:49,91 Juan Maldacena: Well, the gravity waves were going on for a long time, 126 00:11:49,91 --> 00:11:54,84 but the the experiments trying to detect them also took a lot of effort. 127 00:11:54,84 --> 00:11:58,78 We're getting [dramatic 00:11:57] confirmation of both Einstein's theories. 128 00:12:00,01 --> 00:12:03,61 Moreover, the [seasons 00:12:02] of black holes. 129 00:12:03,61 --> 00:12:09,01 This theory of special relativity of general relativity, well Einstein the other equations, 130 00:12:09,01 --> 00:12:13,4 but then there was a lot of research trying to understand the solutions of equations. 131 00:12:13,41 --> 00:12:24,02 The physical interpretation of the solutions. For example, black holes were really only understood in the ‘60s. 132 00:12:24,02 --> 00:12:24,5 Even theoretically. 133 00:12:24,5 --> 00:12:29,29 Then understanding them better then led to understanding what things you should look for in the sky, 134 00:12:29,29 --> 00:12:35,33 and some objects in the sky were recognized as probably endings of black holes, 135 00:12:35,33 --> 00:12:43,06 and now we have this guy with the world detection which appears to come from the coalition of two black holes. 136 00:12:43,06 --> 00:12:46,21 Interviewer: You think so? 137 00:12:46,21 --> 00:12:53,41 Juan Maldacena: That’s a model to describe it. The only announce one coalition. 138 00:12:53,41 --> 00:13:03,49 Probably they see more, it will become more and more convincing.. 139 00:12:59,3 --> 00:13:03,3 Interviewer: Yeah. Because this is the first one. It’s a question of time that more of this [crosstalk 00:13:04] 140 00:13:03,49 --> 00:13:05,05 Juan Maldacena: You would hope. 141 00:13:05,05 --> 00:13:06,05 Interviewer: Yeah. 142 00:13:06,05 --> 00:13:11,43 Juan Maldacena: That’s all about Einstein theory of relativity. 143 00:13:11,43 --> 00:13:16,00 Einstein theory of general relativity is a theory where space time is dynamical. It’s something that moves. 144 00:13:16,00 --> 00:13:23,66 It’s not the starting thing. It’s an actor in physics. It’s not the stage in which physics happens. 145 00:13:24,89 --> 00:13:28,86 It is the stage for all particle physics. For all the matter and so on. 146 00:13:29,47 --> 00:13:32,31 You have the space time and then matter moves in that space time. 147 00:13:32,93 --> 00:13:37,67 Also space time reacts to the presence of matter, and it moves itself. 148 00:13:39,62 --> 00:13:44,39 Through cosmology, this expansion of the space time is very important. 149 00:13:44,39 --> 00:13:47,62 Space time expands and it cools because of that expansion. 150 00:13:47,7 --> 00:13:53,15 Expansion of space time is very important for getting to the universe. 151 00:13:53,15 --> 00:13:59,69 What it is and structure of matter to what it is. This expansion is important for cooling the universe 152 00:13:59,69 --> 00:14:04,71 and then further the force of gravity creates the structures that we have in the universe. 153 00:14:04,71 --> 00:14:20,84 Such as galaxies and planets and so on. It’s important for explaining nature as we said.. 154 00:14:13,58 --> 00:14:20,71 Theory of relativity in some sense is incomplete. Because it [crosstalk 00:14:21] 155 00:14:20,84 --> 00:14:21,21 Interviewer: Incomplete? 156 00:14:21,21 --> 00:14:22,57 Juan Maldacena: Incomplete. 157 00:14:26,27 --> 00:14:33,39 In the sense that if you start out with some initial conditions which are reasonable, the system evolves 158 00:14:33,39 --> 00:14:37,58 and creates so called singularities. You can solve the equations. 159 00:14:37,58 --> 00:14:41,51 You find situations where the curvature of space time becomes infinite. 160 00:14:41,51 --> 00:14:45,78 This happens for example when black hole collapses. 161 00:14:45,78 --> 00:14:50,92 In the interior of the black hole, there’s a region with infinite space time curvature. 162 00:14:50,92 --> 00:14:56,5 Space time becomes so curved, and so … The force of gravity somehow becomes infinite there. 163 00:14:56,5 --> 00:15:00,26 If you were to fall in there, you would be ripped apart. 164 00:15:04,96 --> 00:15:08,05 We don’t have a theory that … The current theory is like general theory 165 00:15:08,05 --> 00:15:12,58 and particle physics do not explain what happens in that situation. 166 00:15:12,58 --> 00:15:18,96 Interviewer: Are you looking for the explanation? 167 00:15:18,96 --> 00:15:28,21 Juan Maldacena: Yeah. Those are the theories we have.. 168 00:15:21,74 --> 00:15:30,42 I think maybe we can make a small bit of smile [crosstalk 00:15:25] Maybe I want to tell them to be quiet. 169 00:15:30,42 --> 00:15:36,14 Interviewer: We were at the point that you were trying to connect the theories. 170 00:15:36,14 --> 00:15:42,88 Juan Maldacena: Yeah. The Einstein theory works very well for many, many things we observe. 171 00:15:43,69 --> 00:15:49,31 The equations themselves fail in some situations. One situation is when matter collapses in a black hole. 172 00:15:49,31 --> 00:15:53,77 The interior of the black hole, we got the region with very high curvature. 173 00:15:55,04 --> 00:15:57,61 If you were to fall in there, you would be ripped apart. 174 00:15:57,61 --> 00:16:03,43 The equations don’t allow us to [the eye 00:16:02] what happens to matter when that happens. 175 00:16:04,05 --> 00:16:06,79 Another interesting situation is if you evolve the equations backwards, 176 00:16:06,79 --> 00:16:12,94 and you try to find out what happened in the very beginning of the big bang. Also the current theories don’t explain. 177 00:16:12,94 --> 00:16:17,73 It cannot explain what happened. Again the expansion would be so rapid, 178 00:16:18,28 --> 00:16:27,37 that space expanding so rapidly you couldn’t … You cannot … The eye what happens. 179 00:16:27,37 --> 00:16:34,02 The equations themselves, the curvature becomes infinite, and the equations fail. The reason … Yeah? 180 00:16:34,02 --> 00:16:40,61 Interviewer: If I try to imagine of course what’s happening inside your head trying to connect these theories, 181 00:16:41,06 --> 00:16:42,25 what happens? 182 00:16:42,25 --> 00:16:47,9 Juan Maldacena: The main reason for these inconsistencies is the fact that they … Einstein’s theories so called 183 00:16:47,9 --> 00:16:59,4 Classical Theory, which is a good theory when things are very big. 184 00:17:00,14 --> 00:17:05,63 Basically very short distances, you have to take into account the quantum. 185 00:17:06,24 --> 00:17:09,48 The same way that matter of long distances can be described, also classically. 186 00:17:09,61 --> 00:17:14,6 When you go to short distances, you have to describe it using the quantum mechanical description. 187 00:17:14,6 --> 00:17:16,51 Space time is similar. 188 00:17:16,51 --> 00:17:22,28 When you go to very short distance in space time, you also would need quantum mechanical description. 189 00:17:22,95 --> 00:17:35,18 For matter, when we go to short distances, we go to the atoms, the elementary particles and so on. For space time,. 190 00:17:28,19 --> 00:17:35,05 we should go again to something that will be atoms of space time. I think that the [crosstalk 00:17:35] 191 00:17:35,18 --> 00:17:35,83 Interviewer: What is that? 192 00:17:35,83 --> 00:17:45,93 Juan Maldacena: We think that we went to such a theory, we could do this. We could perhaps understand the big bang.. 193 00:17:42,69 --> 00:17:45,83 Or, the situations which we cannot understand [crosstalk 00:17:46] 194 00:17:45,93 --> 00:17:47,87 Interviewer: Define the atoms of space time. 195 00:17:47,87 --> 00:17:57,57 Juan Maldacena: I can’t define the atoms of space time. We’re trying to find what they are. 196 00:18:02,18 --> 00:18:08,05 One idea that is wrong, is the idea that there would be atoms at each different locations in space, and so on. 197 00:18:08,05 --> 00:18:10,6 Space time is not like continuing matter. 198 00:18:10,6 --> 00:18:17,72 Because, one important property that was understood theoretically is that, 199 00:18:18,39 --> 00:18:24,09 when you have the number of configurations in original space time, that number configurations, 200 00:18:24,09 --> 00:18:28,41 does not grow like the volume. As it would with only matter. 201 00:18:28,73 --> 00:18:31,43 The number of atoms somehow wherever they are, of space time, 202 00:18:31,64 --> 00:18:34,33 we know that their number grows like the area of the surface. 203 00:18:34,83 --> 00:18:46,77 Rather than the volume. That’s an interesting property of this so called atoms of space time. 204 00:18:46,77 --> 00:18:53,38 By atoms of space time I mean, well basically vague idea but I try to motivate it in this way. 205 00:18:53,84 --> 00:19:00,94 The search for a theory that describes space time at the quantum mechanical level. Using the laws of quantum mechanics. 206 00:19:00,94 --> 00:19:06,6 The laws of quantum mechanics are laws which are intrinsically probabilistic. 207 00:19:06,6 --> 00:19:09,12 That’s the main difference from the laws of classical physics. 208 00:19:09,22 --> 00:19:16,72 Classical physics, if you know the initial conditions, you can then calculate what would happen in the future.. 209 00:19:16,35 --> 00:19:16,54 [crosstalk 00:19:17] 210 00:19:16,72 --> 00:19:18,58 Interviewer: Because you cannot do an experiment you mean? 211 00:19:18,58 --> 00:19:21,41 Juan Maldacena: No, in quantum mechanics you can do experiments. 212 00:19:21,65 --> 00:19:26,6 The results you can prepare the initial conditions always in the same way. 213 00:19:26,77 --> 00:19:31,91 The results of the climates will be different each time you experiment, you’ll get a different answer. 214 00:19:31,91 --> 00:19:39,31 All you can predict according to quantum mechanics is not the precise answer of the experiment, 215 00:19:39,31 --> 00:19:49,28 but the probabilities for the different answers. You do an experiment, it’s like flipping a coin. 216 00:19:49,28 --> 00:19:58,08 You can calculate and you can say, maybe I’ll get 50% one result. 50% of the time one result and 50% the other. 217 00:19:58,08 --> 00:20:05,95 Or maybe it’s 30, 70 and so on. Quantum mechanics allows you to calculate those percentages. 218 00:20:05,95 --> 00:20:15,26 Quantum mechanics doesn’t allow you to give definite answers to some questions. It is intrinsically this way. 219 00:20:15,26 --> 00:20:18,59 Interviewer: That’s a rather big question you ask yourself. 220 00:20:18,59 --> 00:20:26,51 Besides the part that you are this scientist trying to research this. 221 00:20:26,51 --> 00:20:39,37 I’m also interested why is it you asking this question? What’s your … Why do you ask this question? 222 00:20:39,51 --> 00:20:41,3 Why do you do this? 223 00:20:41,3 --> 00:20:48,57 Juan Maldacena: Certainly I’m not the first to ask this question. This question was asked many years ago. 224 00:20:48,57 --> 00:20:54,4 Probably Planck was the first to realize that there was a connection between the quantum and gravity. 225 00:20:54,82 --> 00:21:03,7 At some point gravity would fail, and calculated what distance scale you would [inaudible 00:21:01] was a century ago. 226 00:21:04,28 --> 00:21:10,61 Since then, people have had various ideas by thinking about this problem. 227 00:21:13,34 --> 00:21:17,13 It’s a problem that is hard to access it fundamentally directly. 228 00:21:17,33 --> 00:21:20,35 This distance in which the quantum is important is super tiny. 229 00:21:20,35 --> 00:21:25,16 It’s much smaller than the smallest distances we can see today will accelerate this. 230 00:21:25,16 --> 00:21:36,11 By a group of people who are trying to investigate this from the theoretical point of view, 231 00:21:36,11 --> 00:21:43,35 trying to find the structure of mathematical theory that would put these two things together. We’re trying to do 232 00:21:43,35 --> 00:21:50,48 something similar to what Einstein did when he joined special relativity with Newtonian gravity. 233 00:21:50,57 --> 00:21:57,29 He realize that the theory of Newton was not consistent with this idea that the speed of light is the maximum speed of 234 00:21:57,29 --> 00:22:03,1 propagation of signals. That it should be the same for all observers. 235 00:22:03,1 --> 00:22:06,54 Putting those two things together, he managed to create the structure. The structure of general relativity. 236 00:22:07,12 --> 00:22:15,9 Here we are trying to replicate that from theoretical points of view,. 237 00:22:11,47 --> 00:22:23,86 try to find the connections between the quantum and space time, and [crosstalk 00:22:17]. 238 00:22:15,9 --> 00:22:23,84 Interviewer: Are you sure you’re going to find the answers or [crosstalk 00:22:20] 239 00:22:23,86 --> 00:22:30,31 Juan Maldacena: No. We’re not 100% sure, but we’re confident that we have a high probability. 240 00:22:30,31 --> 00:22:35,35 The equation is so interesting, that we should try to investigate it. 241 00:22:35,35 --> 00:22:38,93 Interviewer: You know that you’re on the right path? 242 00:22:38,93 --> 00:22:39,7 Juan Maldacena: Yeah. 243 00:22:40,22 --> 00:22:49,88 What gives us some confidence that we’re in the right path is that, we’re not investigating this in the vacuum 244 00:22:49,88 --> 00:22:58,47 or without … We now have some very concrete theories. The nicest one is the theory of strength theory. 245 00:22:59,58 --> 00:23:05,02 That is a theory based on the construction that works very nicely in some situations. 246 00:23:05,02 --> 00:23:09,52 That manages to join the quantum with space time. 247 00:23:10,01 --> 00:23:17,65 Is a theory under construction, and a theory which is continued to be developed and we’re trying to understand it. 248 00:23:17,65 --> 00:23:18,24 Interviewer: Strength theory. 249 00:23:18,24 --> 00:23:24,91 Juan Maldacena: Yeah. Strength theory. It seems to connect the quantum with space time in a very interesting way. 250 00:23:24,91 --> 00:23:33,85 By investigating strength theory, people have found very interesting mathematical relations. That are true mathematics. 251 00:23:34,00 --> 00:23:37,98 They found the connections between different physical theories. 252 00:23:38,7 --> 00:23:43,13 For example, between the theory of strong interactions and some theories of space time. 253 00:23:46,27 --> 00:23:55,47 The fact that the disconnections were found,, 254 00:23:49,59 --> 00:23:55,3 gives us some confidence that at least the structure that we’re investigating is interesting and [great 00:23:56] 255 00:23:55,47 --> 00:23:59,39 and it could be the answer to this question of quantum gravity. 256 00:23:59,39 --> 00:24:03,71 Which is really the main question we’re trying to answer. 257 00:24:03,71 --> 00:24:12,5 Interviewer: Do you work in a group of people who are on the same level theoretically? 258 00:24:12,5 --> 00:24:13,5 Juan Maldacena: Yeah. 259 00:24:13,5 --> 00:24:24,38 Interviewer: How is it for you to … Now you have to explain it to me, and I don’t understand. 260 00:24:24,52 --> 00:24:29,71 You have to transfer your thoughts or your ideas to people who don’t understand. 261 00:24:29,95 --> 00:24:35,01 Because it’s so difficult even for yourself, it’s difficult. How is that? 262 00:24:35,01 --> 00:24:39,72 Juan Maldacena: Well, for us it’s difficult to find the equations, 263 00:24:40,52 --> 00:24:46,3 but I think what I’m trying to compare is the problem we’re trying to understand 264 00:24:46,3 --> 00:24:48,18 and I think the problem is understandable. 265 00:24:48,19 --> 00:24:55,74 It’s just joining two theories of physics that are out there, and putting them together. 266 00:24:56,03 --> 00:24:58,19 They are not completely compatible with each other. 267 00:24:58,35 --> 00:25:02,04 In the history of physics, when there were two kinds of theories that were not quite compatible, 268 00:25:02,04 --> 00:25:06,31 and you find a structure that puts them together, it might be the right structure. 269 00:25:06,31 --> 00:25:09,12 Interviewer: This theory might be the strength theory? 270 00:25:09,12 --> 00:25:14,96 Juan Maldacena: Yeah. The strength theory is the main tool and the main thing that we’re investigating. 271 00:25:15,11 --> 00:25:22,95 We think that it is not the right structure. It’s probably close to the right structure.. 272 00:25:20,81 --> 00:25:22,79 It could be the stepping stone to the right structure. [crosstalk 00:25:25] 273 00:25:22,95 --> 00:25:26,55 Interviewer: For a lot of people, the strength theory is un-understandable, 274 00:25:26,55 --> 00:25:34,85 but you all have to understand this theory just to use it as a possible? 275 00:25:34,85 --> 00:25:35,52 Juan Maldacena: Yeah. 276 00:25:35,52 --> 00:25:38,09 Strength theory might sound complicated, 277 00:25:38,59 --> 00:25:53,12 but it’s something that someone who’s doing his PhD in physics can learn in a year, a couple of years,. 278 00:25:46,92 --> 00:25:55,86 and they can [crosstalk 00:25:47] That’s right... 279 00:25:53,45 --> 00:25:55,6 Interviewer: Maybe [crosstalk 00:25:54] Can you explain to me what [crosstalk 00:25:56] 280 00:25:55,86 --> 00:25:58,02 Juan Maldacena: There is … It’s like playing the piano. 281 00:25:58,02 --> 00:26:01,76 You’re not going to be able to play the piano in five minutes. 282 00:26:01,76 --> 00:26:08,01 Someone can tell you, oh you have to press keys and so on but you won’t be able to play the piano 283 00:26:08,01 --> 00:26:08,93 or to produce nice music. 284 00:26:08,93 --> 00:26:10,52 Interviewer: It sounds awful. 285 00:26:10,52 --> 00:26:18,33 Juan Maldacena: Here also, it takes a while to get familiar. To familiarize yourself with the ideas. 286 00:26:18,68 --> 00:26:23,59 One reason we have this is because you really have to learn a lot of the physics that precedes it. 287 00:26:24,00 --> 00:26:32,18 You have to learn well general relativity, you have to learn well particle theory of interacting particles. 288 00:26:32,18 --> 00:26:34,17 You have to do this. 289 00:26:34,17 --> 00:26:39,71 Interviewer: Isn’t it a fact that if different people from different backgrounds come together 290 00:26:41,26 --> 00:26:51,32 and discuss this strength theory, that in the event that they all know what you’re talking about, 291 00:26:51,32 --> 00:26:57,51 or understand the strength theory, doesn’t make it then true? 292 00:26:57,51 --> 00:27:05,19 Juan Maldacena: No. What makes a physical theory true, as a physics theory of physics is comparison with experiment. 293 00:27:05,19 --> 00:27:12,96 Interviewer: If you all understand the strength theory and then you think it’s true, you understand what it means, 294 00:27:12,96 --> 00:27:18,52 it took some years but different other people took some years and they understand strength theory. 295 00:27:18,52 --> 00:27:21,08 Juan Maldacena: Strength theory today is a mathematical structure. 296 00:27:21,24 --> 00:27:25,89 It’s a mathematical structure which has some physical interpretation. 297 00:27:26,05 --> 00:27:28,75 We don’t yet know whether it’s the right theory of physics. 298 00:27:28,9 --> 00:27:38,69 We think it’s in the right track, and we’re motivated enough to continue stirring it. That doesn’t make it true. 299 00:27:38,69 --> 00:27:41,99 That just makes it a very interesting mathematical theory. 300 00:27:41,99 --> 00:27:45,83 Interviewer: Can you explain to me what is meant by this strength theory? 301 00:27:45,83 --> 00:27:49,00 Juan Maldacena: Well, 302 00:27:49,00 --> 00:27:57,65 mainly strength theory is a theory which some laws that can describe space time at the quantum mechanical level. 303 00:27:58,05 --> 00:28:09,38 Using the laws of quantum mechanics. That it reduces to Einstein theory for big distances. That’s its main advantage. 304 00:28:09,38 --> 00:28:12,05 Now, maybe you are asking why is it called strength. 305 00:28:12,05 --> 00:28:19,27 Well, this comes in the fact that [man 00:28:18] formulation of the theory, 306 00:28:19,62 --> 00:28:23,29 you have little tiny vibrating loops of strength. 307 00:28:23,29 --> 00:28:30,81 Instead of having particles which are point like, as we have in theory of particles, or innate particles, 308 00:28:32,13 --> 00:28:37,32 the elementary objects are a little strengths. One dimension objects. 309 00:28:37,69 --> 00:28:40,67 That’s … Using those, 310 00:28:41,19 --> 00:28:48,58 you can describe ripples of space time interacting. All those gravity waves that we discussed before in the experiment, 311 00:28:49,09 --> 00:28:57,95 when they interact in a quantum mechanical way. They can do so in a way that’s not generating any inconsistency. 312 00:28:57,95 --> 00:29:09,92 Interviewer: Is there a theory of your own which you are investigating or researching? 313 00:29:09,92 --> 00:29:19,13 Juan Maldacena: I’ve been researching some relationship between strength theory and particle physics. 314 00:29:19,13 --> 00:29:23,47 There’s a relationship which is part of this connections that I was describing before. 315 00:29:24,12 --> 00:29:25,73 That the strength theory led to. 316 00:29:25,73 --> 00:29:32,19 This is a connection between theories of gravity in the interior of the space time, 317 00:29:32,19 --> 00:29:35,63 and the theory of particles on the boundary of the space time. 318 00:29:36,67 --> 00:29:42,28 In this relationship, the idea is that the so called atoms of space time in the interior, 319 00:29:42,28 --> 00:29:46,28 are like particles on the boundary. That’s roughly one way to say. 320 00:29:47,99 --> 00:29:51,11 Another analogy people make sometimes is the idea of the hologram. 321 00:29:51,11 --> 00:29:58,87 That you can … A hologram is a two dimensional photographic plate. That when you illuminate it in the light, 322 00:29:58,87 --> 00:30:00,69 you see three dimensional picture. 323 00:30:00,69 --> 00:30:08,97 The idea is that you can have the dynamics of this particle on the boundary or space time so far away. 324 00:30:08,97 --> 00:30:15,47 Can have an alternative description as objects moving in the interior. Subject to the force of gravity. 325 00:30:15,47 --> 00:30:23,17 Interviewer: The atoms of space time are reflected or projected? 326 00:30:23,17 --> 00:30:30,72 Juan Maldacena: Yeah. The real atoms would be on the boundary. The real elementary particles, another thing. 327 00:30:31,56 --> 00:30:37,79 Then we’ve got some effective description … approximate description in terms of a space time in the interior. 328 00:30:38,39 --> 00:30:41,22 In this picture, space time is … This is just an approximation. 329 00:30:41,22 --> 00:30:46,82 It’s an approximation to the dynamics of lots of particles. 330 00:30:47,18 --> 00:30:55,95 In the same way that properties of microscopic objects come from similar approximations, like the scarcity of water 331 00:30:55,95 --> 00:30:58,55 or just the behavior of water waves and so on. 332 00:30:58,55 --> 00:31:07,82 It comes from the collective motion of many of the concentrated molecules. 333 00:31:07,82 --> 00:31:12,67 Interviewer: The thing you’re explaining to me how it works this hologram again? As simple as possible. 334 00:31:12,67 --> 00:31:19,97 Juan Maldacena: This idea is the idea that you can describe gravitational physics, 335 00:31:19,97 --> 00:31:24,64 or dynamics of space time at the quantum level. Which is something we don’t understand too well how to do it. 336 00:31:24,64 --> 00:31:29,52 In terms of theory of particles. That lives on the boundary of that space time. 337 00:31:29,52 --> 00:31:34,1 The theory of particles is very similar to the theory of particles we use for particle physics. 338 00:31:34,53 --> 00:31:45,07 Or, some similar to the theory we use in the quantum mechanics. That’s a disconnection. 339 00:31:45,07 --> 00:31:52,73 It connects for example black holes, to come on systems of particles that find the temperature. 340 00:31:56,28 --> 00:32:05,39 If you assume … It’s a conjecture that these two things are related. It’s a conjecture that people work a lot on 341 00:32:05,39 --> 00:32:11,06 and they found lots of ideas that this correct at least in very specific cases. 342 00:32:11,06 --> 00:32:16,84 It’s a conjecture a conjecture between two let’s say mathematical theories. 343 00:32:16,99 --> 00:32:23,24 One is the mathematics of strength theory in the space times, or quantum mechanical dynamical space times. 344 00:32:23,24 --> 00:32:28,85 That’s described through strength theory, and ordinary theories of particle physics. 345 00:32:29,5 --> 00:32:35,57 Many cases we can approximately describe each of the two sides, and then check mathematically that they’re correct. 346 00:32:35,57 --> 00:32:42,04 The idea is to understand this further. 347 00:32:42,04 --> 00:32:47,06 To understand better how space … What this implies for space time, 348 00:32:47,06 --> 00:32:54,27 and how to build better theories of space time. In particular how to solve some of the problems we have with black 349 00:32:54,27 --> 00:32:54,93 holes. 350 00:32:54,93 --> 00:33:09,05 Black holes are understood reasonably well with the theory of Einstein’s … With Einstein’s theory of relativity. 351 00:33:09,05 --> 00:33:11,09 Black holes have also give rise to some quantum mechanical effects. 352 00:33:11,99 --> 00:33:15,15 More precisely once you take into account quantum mechanics. 353 00:33:15,77 --> 00:33:19,52 Black holes can start to emit some kind of radiation Hawking discovered. 354 00:33:19,52 --> 00:33:25,98 He discovered this theoretically, and it’s called Hawking radiation. 355 00:33:25,98 --> 00:33:32,23 This implies that black holes are they form, and then they start emitting this radiation. 356 00:33:32,23 --> 00:33:34,69 They emit a kind of soft glow. 357 00:33:36,34 --> 00:33:41,54 Just to highlight how surprising this radiation is, 358 00:33:41,54 --> 00:33:48,8 black holes were called black because they don’t emit any light. Anything that goes in has to fall in 359 00:33:48,8 --> 00:33:50,35 and nothing can be emitted. 360 00:33:50,35 --> 00:33:51,83 Interviewer: Can get out? 361 00:33:51,83 --> 00:33:56,46 Juan Maldacena: Cannot get out. This radiation is something that is somehow getting out. 362 00:33:56,46 --> 00:34:00,29 You can even have the [inaudible 00:33:58] situation of having a white black hole. 363 00:34:00,29 --> 00:34:03,99 You have a black hole which is very tiny. 364 00:34:04,94 --> 00:34:09,66 The size of the wave length of light, or the size of a bacteria roughly speaking. 365 00:34:09,66 --> 00:34:15,83 That black hole will look white to our eyes. These black holes don’t form naturally in nature. 366 00:34:15,83 --> 00:34:19,8 Black holes that form naturally in nature, are very big and have a very low temperature. 367 00:34:20,24 --> 00:34:25,00 If you could form such a tiny black hole, theories predict that it should look white. 368 00:34:25,00 --> 00:34:29,34 Here you see that there’ll be little conflict between Einstein’s theory of relativity, 369 00:34:29,58 --> 00:34:36,06 in the beginning of a conflict you see it. One says it should be black, and the other one says it should be white. 370 00:34:36,06 --> 00:34:37,32 Interviewer: White hole. 371 00:34:37,32 --> 00:34:43,06 Juan Maldacena: Yeah. This is different from what people call a white hole, but this is a white black hole. 372 00:34:43,06 --> 00:35:01,67 Here you see the beginning of some slight conflict between the two, and if you go deeper in,. 373 00:34:54,4 --> 00:35:03,4 there are some laws of thermodynamics that should apply to any option that emits thermal .. This radiation is thermal. 374 00:35:03,4 --> 00:35:11,14 It gets emitted at a certain temperature. That’s why you needed to make it very small, to make it look white. 375 00:35:11,36 --> 00:35:14,88 Because the temperature becomes higher. The smaller the black hole is. 376 00:35:15,27 --> 00:35:18,94 Small black hole is hotter than a bigger black hole. 377 00:35:18,94 --> 00:35:23,02 I should make the black hole smaller, 378 00:35:23,02 --> 00:35:30,83 it gets hotter. If you apply it with the laws of thermodynamics as we usually understand them, 379 00:35:31,37 --> 00:35:34,11 they seem to hold for such black holes. 380 00:35:35,24 --> 00:35:40,17 They are … They seem to be in some conflict with another fact that we know from general relativity. 381 00:35:40,78 --> 00:35:46,37 Which is that if you solve the Einstein’s equations in black hole, there is a surface that we call the horizon. 382 00:35:46,8 --> 00:35:51,74 Which is a surface basically right on the outside, and the inside. It’s an imaginary surface. 383 00:35:51,74 --> 00:35:57,21 It’s not a real surface. It’s kind of point of no return. 384 00:35:58,07 --> 00:36:06,54 If you cross the horizon, in the interior, you cannot send anything to the outside. You cannot even escape. 385 00:36:06,54 --> 00:36:12,78 You’ll be doomed to fall in the singularity. You don’t feel anything when you cross the horizon. 386 00:36:12,78 --> 00:36:19,75 It’s a perfectly reasonable surface. That’s what Einstein’s theory predicts. 387 00:36:23,44 --> 00:36:29,38 This fact seems to somehow be in some conflict with this thermal properties of black holes, 388 00:36:29,38 --> 00:36:40,68 and how to fully resolve this conflict. Is one of the things I and some other people are working on. 389 00:36:40,68 --> 00:36:44,25 Interviewer: Is it something that you can call your life work? 390 00:36:44,25 --> 00:36:53,87 Juan Maldacena: I would say that I’ve been mostly investigating this relationship between the interior 391 00:36:53,87 --> 00:37:01,48 and the boundary. Also, trying to understand these problems with black holes. These problems with black holes. 392 00:37:01,48 --> 00:37:03,48 The aspects of black holes. 393 00:37:03,48 --> 00:37:16,5 Interviewer: Is this like your life researching this? Or is this just a job? 394 00:37:16,5 --> 00:37:24,79 Juan Maldacena: It is a passion and I would like to really find the problem, and find a solution to the problem. 395 00:37:30,83 --> 00:37:32,08 I hope it gets solved soon. 396 00:37:32,08 --> 00:37:34,03 Interviewer: Are you close? 397 00:37:34,03 --> 00:37:38,16 Juan Maldacena: Yeah. We seem to be close. Hopefully yes. 398 00:37:38,16 --> 00:37:50,67 Interviewer: What I try to imagine, is because it’s also theoretical. You must have a big imagination. 399 00:37:52,02 --> 00:37:54,3 When you think about it, what do you see? 400 00:37:55,92 --> 00:38:08,00 Is it … And I don’t want you to explain the theory, but how do you represent this in your head? In your brain? 401 00:38:08,88 --> 00:38:11,77 In colors, or in shapes, or in? 402 00:38:11,77 --> 00:38:12,68 Juan Maldacena: Yeah. 403 00:38:12,68 --> 00:38:17,82 Probably in terms of …By the way, we imagine formulas and their properties, 404 00:38:17,82 --> 00:38:21,65 and we make a little mental image for these formulas. 405 00:38:21,65 --> 00:38:28,76 We … For example, already for Einstein theory of relativity you have to imagine space time as some kind of membrane. 406 00:38:28,76 --> 00:38:31,47 Interviewer: How do you imagine that? 407 00:38:31,47 --> 00:38:35,25 Juan Maldacena: I imagine it same for classical space time for example, as a membrane 408 00:38:35,25 --> 00:38:41,47 and the quantum one a membrane that is fluctuating. Those are the kind of mental images that we … 409 00:38:41,47 --> 00:38:42,73 Interviewer: Sorry, a membrane? 410 00:38:42,73 --> 00:38:50,58 Juan Maldacena: Well, space time is like a membrane that has certain shape. Has some dynamics of the shape can change. 411 00:38:51,26 --> 00:38:58,13 If you get very close, this membrane has some oscillations and some structure. 412 00:38:58,77 --> 00:39:09,29 That’s what we have at short distances. That’s a picture of the smallest standard for how to think about this. 413 00:39:09,29 --> 00:39:20,68 One of the interesting things that we’ve been trying to understand and many people have begun to notice is that, 414 00:39:20,68 --> 00:39:26,3 there is some connection between a certain property of quantum mechanics called entanglement. 415 00:39:26,3 --> 00:39:36,4 Entanglement is a funny kind of correlation you can have in quantum mechanical systems. Which in some sense stronger 416 00:39:36,4 --> 00:39:37,73 than classical correlations. 417 00:39:40,55 --> 00:39:44,46 Before we discuss the fact that in some quantum mechanical systems you cannot predict the answer to certain experiments. 418 00:39:45,05 --> 00:39:54,61 You might sometimes find 50% chance of one, or 50% chance of the other. 419 00:39:54,61 --> 00:40:00,08 You’re going to have systems where you have two particles, and they’re separated. 420 00:40:00,08 --> 00:40:03,97 You’re going to experiment here and you have 50% chance of each outcome. 421 00:40:03,97 --> 00:40:09,44 You can do another experiment here and it’s again 50% chance of any outcome. 422 00:40:09,44 --> 00:40:18,64 It might turn out that the outcomes of the two experiments are correlated. Let’s say the experiment is like flipping 423 00:40:18,64 --> 00:40:21,17 a coin, it comes out heads here and it also comes out heads here. 424 00:40:21,17 --> 00:40:26,19 If it comes tails here, it also will come out tails here. They’re perfectly correlated. 425 00:40:26,63 --> 00:40:28,73 That’s an example of a classical correlation. 426 00:40:28,73 --> 00:40:35,44 Entanglement is the fact that you can also measure another property at the same time. 427 00:40:35,55 --> 00:40:39,72 If this coin which is not heads or tails but it’s the color, this is another analogy. 428 00:40:39,72 --> 00:40:45,16 If the property is quantum mechanical that cannot be measure at the same time as the original property. 429 00:40:47,17 --> 00:40:49,64 That’s one of the features also. Quantum mechanics. 430 00:40:50,15 --> 00:41:01,37 That sometimes you can have two properties which you cannot measure at the same time. You can ask this coin whether 431 00:41:01,37 --> 00:41:02,55 it’s heads or tails. 432 00:41:02,55 --> 00:41:08,02 Or whether it says it’s black or white but you cannot ask where it’s black, and where it’s heads or tails. 433 00:41:08,02 --> 00:41:16,33 It’s not a perfect analogy, or a classical variables are not of this kind. They’re mutually incompatible. 434 00:41:16,33 --> 00:41:24,69 You can do that with this quantum let’s say properties, and again you can have two particles so that, 435 00:41:24,69 --> 00:41:29,64 if you now measure, not only whether it’s heads or tails, but also black or white, 436 00:41:29,98 --> 00:41:32,73 you have the same perfect correlation with the other. 437 00:41:34,15 --> 00:41:41,32 That some kind of correlation that is not possible in classical physics, but it’s possible in quantum physics.. 438 00:41:40,81 --> 00:41:41,28 We think that [crosstalk 00:41:43] 439 00:41:41,32 --> 00:41:42,35 Interviewer: Even though there’s a big distance? 440 00:41:42,35 --> 00:41:45,02 Juan Maldacena: Yeah. Even though there is a big distance. 441 00:41:45,02 --> 00:41:51,33 Again, with classical correlations, we can have these correlations because the two … You prepare the two kinds first, 442 00:41:51,33 --> 00:41:56,56 and then you take them apart. Then you look at it. In classical physics, there’s no problem with this correlation. 443 00:41:58,05 --> 00:42:04,64 What is interesting is that you can have correlation between variables that are mutually incompatible locally. 444 00:42:04,64 --> 00:42:10,56 By compatible I mean that you either measure one or the other, but nevertheless you have a correlation. 445 00:42:10,56 --> 00:42:19,07 Sometimes [inaudible 00:42:17] surprising property quantum mechanics, when it was noticed, 446 00:42:19,07 --> 00:42:26,44 it was noticed in that paper by Einstein [inaudible 00:42:22] in the 1930s. Then while this was property, 447 00:42:29,75 --> 00:42:38,24 and now it’s quite central notion for quantum information theory and people are using it in more practical ways. 448 00:42:39,31 --> 00:42:44,09 To build … I mean, it would be essential for building quantum mechanical computer systems. 449 00:42:45,51 --> 00:42:50,69 It also seems to be connected with the connections in space time. 450 00:42:50,69 --> 00:42:56,67 Things that are closer to getting space time are more entangled with each other. 451 00:42:57,92 --> 00:43:06,07 In some sense when you have the quantum field theory vacuum. The vacuum in the theory of particle physics. 452 00:43:06,07 --> 00:43:08,63 If you want to split it in two parts, 453 00:43:08,63 --> 00:43:19,45 the fundamental degrees of freedom are quantum variables that describe it. Are quite entangled with each other. 454 00:43:19,45 --> 00:43:25,84 We think that in some circumstances if you take two separate systems, and you entangle them very strongly, 455 00:43:26,23 --> 00:43:32,63 so you could also generate some kind of quantum connect. You can generate geometric connection between them. 456 00:43:32,64 --> 00:43:47,04 In some cases. In some sense, through the entanglement is connected to the connectivity of space time. You can, yeah. 457 00:43:47,04 --> 00:43:54,8 Interviewer: I want to try to get back to the beginning again. 458 00:43:58,14 --> 00:44:10,43 Because it’s rather difficult and I doubt you told me a lot about it. I try to recapture a little bit if I’m right. 459 00:44:13,05 --> 00:44:31,39 I would like to ask you to give definitions of the ingredients. Definitions for normal people. 460 00:44:31,39 --> 00:44:35,71 What is time, what is space and what is relativity? 461 00:44:35,71 --> 00:44:44,6 Juan Maldacena: Okay, good. Let’s start with time. Time is what the clock measures. 462 00:44:44,6 --> 00:44:48,15 Now, this sounds like a circular definition, 463 00:44:48,16 --> 00:44:54,53 but of course what’s not obvious is that different blocks made in different ways measure the same time. 464 00:44:54,53 --> 00:45:01,65 It turns out if you have different kinds of clocks, and you make them, 465 00:45:01,66 --> 00:45:05,26 they will all measure the same … They’ll measure the same … They’ll give the same answer. 466 00:45:05,26 --> 00:45:10,9 That you can synchronize clocks and they stay synchronize and so on. 467 00:45:10,9 --> 00:45:14,27 It looks like there is something that is being measured by these clocks. 468 00:45:14,27 --> 00:45:17,37 This something is the abstraction we call time. 469 00:45:17,93 --> 00:45:21,83 We have the time we feel psychologically which is not a perfect clock, 470 00:45:21,83 --> 00:45:30,57 but certainly agrees with more precise physical clocks. All clocks that measure time are made of physical particles, 471 00:45:30,57 --> 00:45:35,45 and that’s how we measure time. That’s how we define it. 472 00:45:35,45 --> 00:45:44,89 It’s an abstraction but this is the thing that all these clocks are measuring. What is space? 473 00:45:44,89 --> 00:45:54,7 Space is somehow the distance between the … Let’s say the nothingness that exists between two objects. 474 00:45:55,23 --> 00:46:07,95 Now, it’s what’s missing when you go into a crowded bus. That’s space. What’s this relativity? 475 00:46:08,05 --> 00:46:09,78 Let’s first discuss special relativity. 476 00:46:10,21 --> 00:46:15,14 Before when I was discussing time, I said that all clocks measure the same time. 477 00:46:15,44 --> 00:46:19,79 That is only true for clocks that are stationary. If you have a clock here. 478 00:46:19,79 --> 00:46:23,4 Another clock here, and both stay at rest relative to each other, 479 00:46:23,42 --> 00:46:31,54 then they will measure the same time. If you have a clock here. Another clock moving, they will measure different time. 480 00:46:32,07 --> 00:46:37,93 Relativity, special relative that’s how different is this other time the clock measures. 481 00:46:37,93 --> 00:46:43,82 It’s a simple law for how to find out how to. 482 00:46:46,1 --> 00:46:54,1 The theory of relativity is the theory that postulates the speed of light. It’s constant. It’s absolute. 483 00:46:54,1 --> 00:47:00,62 If you could also have call it absolute something. 484 00:47:00,62 --> 00:47:05,23 What’s relative is time, but that doesn’t mean everything is relative. 485 00:47:05,23 --> 00:47:07,48 Interviewer: This envisioning what is light? 486 00:47:07,48 --> 00:47:14,8 Juan Maldacena: Well, you could replace light by other things like gravity where it’s also propagated the speed. 487 00:47:15,25 --> 00:47:20,75 More precisely, I should have said it’s the maximum speed of propagation of signals. 488 00:47:20,75 --> 00:47:26,11 The idea is that there is a maximum speed for the propagation of signals. 489 00:47:27,09 --> 00:47:29,03 So happens that light propagates at this speed. 490 00:47:29,03 --> 00:47:34,78 If you had a massive particle, it would generally propagate at a lower speed. 491 00:47:35,24 --> 00:47:38,69 If you try to push a massive particle to move it faster and faster and faster, 492 00:47:39,05 --> 00:47:45,62 you could not make it move faster than this maximum speed. Which is also coincides with the speed of light. 493 00:47:45,62 --> 00:47:47,7 Interviewer: That’s why it’s absolute? 494 00:47:47,7 --> 00:47:52,23 Juan Maldacena: Yeah. Different observers would measure exactly the same speed. 495 00:47:52,23 --> 00:48:05,1 Interviewer: Why do you want to have an explanation for how life started? 496 00:48:05,1 --> 00:48:11,32 Juan Maldacena: Well, it’s not an explanation about how life started, but how the beginning of space time started. 497 00:48:11,91 --> 00:48:18,12 How time originated and what happened at the beginning of the big bang. 498 00:48:18,12 --> 00:48:22,64 We’re trying to understand it because that’s something we don’t know. 499 00:48:22,64 --> 00:48:25,53 Science is always about pushing the boundaries. 500 00:48:26,49 --> 00:48:31,85 We don’t … It’s not just the fact that we don’t know how it happened, 501 00:48:31,86 --> 00:48:36,76 but even we don’t have a theory that is [self 00:48:36] consistent that could describe it. 502 00:48:36,76 --> 00:48:44,71 We are even trying to find theories that could in principle describe the big bang,. 503 00:48:43,26 --> 00:48:47,28 then we’ll have the problem of finding .. That’s the way the big bang actually happened. Yeah. 504 00:48:50,02 --> 00:48:55,16 That’s why we think the problem may be solved by thinking about it, and finding the theory 505 00:48:55,16 --> 00:48:59,19 and then perhaps making some new predictions that we could test experimentally. 506 00:48:59,19 --> 00:49:06,87 Interviewer: Yeah, but all the time the same question arises again. What happened before the big bang? 507 00:49:07,1 --> 00:49:11,92 Questions like that. How do you deal with this almost impossible … 508 00:49:11,92 --> 00:49:21,41 Juan Maldacena: The idea is to make a theory, and maybe you can make a theory which has a time before. 509 00:49:21,41 --> 00:49:26,47 Maybe you can make a theory where time actually starts in the big bang, 510 00:49:26,72 --> 00:49:32,12 and does not have any meaning before … Sort of the question doesn’t have a meaning. 511 00:49:32,65 --> 00:49:38,63 We don’t know what the right answer is. That’s what we’re trying to find out with this concept. 512 00:49:38,63 --> 00:49:45,98 People imagine now maybe there was a time before, and somehow we went through a big bang. These are just words. 513 00:49:45,98 --> 00:49:52,32 They are not self-consistent equations where you can have such a thing. 514 00:49:52,4 --> 00:49:58,46 If you try to make a theory where the universe was contracting, and then expanding again for example, 515 00:49:58,87 --> 00:50:04,57 they violate some principles that we think should be true in the theory of quantum gravity. 516 00:50:04,57 --> 00:50:09,86 Interviewer: When did yourself ask this question for the first time? 517 00:50:09,86 --> 00:50:16,54 Juan Maldacena: I guess as I started learning more about physics. 518 00:50:16,54 --> 00:50:24,44 I started recognizing where the boundaries of physics were, and there are boundaries of physics in many directions. 519 00:50:24,44 --> 00:50:28,33 In the direction of very complex systems, in very different directions. 520 00:50:28,63 --> 00:50:36,6 This is one of the directions in which we see a boundary. I wanted to go to the frontier in this direction. 521 00:50:38,73 --> 00:50:44,83 I guess the physics they’re trying to roll was expanding. Push the frontier further and further away. 522 00:50:44,83 --> 00:50:47,3 Interviewer: Right now you are as a frontier? 523 00:50:47,3 --> 00:50:50,02 Juan Maldacena: Yeah. This is certainly one of the frontiers. 524 00:50:50,02 --> 00:50:53,36 Interviewer: What do you see when you look ahead? 525 00:50:53,36 --> 00:50:59,83 Juan Maldacena: I see confusion. I see lack of understanding. 526 00:50:59,83 --> 00:51:07,5 The idea is to find patterns in this confusion, and to move forward. 527 00:51:07,5 --> 00:51:12,82 To understand things that we currently don’t understand [crosstalk 00:51:11] bit by bit. 528 00:51:12,92 --> 00:51:19,94 Usually you advance one step at a time, and get a little further, and a little further, and. 529 00:51:19,94 --> 00:51:23,38 Interviewer: Do you feel something like a competitor? 530 00:51:24,46 --> 00:51:34,00 Or, something like a challenge or something which challenges some things … Some works. 531 00:51:34,63 --> 00:51:41,95 Somebody who challenges you to try to find it. Something like that. 532 00:51:41,95 --> 00:51:47,67 Juan Maldacena: Yeah. Certainly we were trying to find this answer, and we really want to get the answer. 533 00:51:48,24 --> 00:51:51,4 Sometimes you feel, sometimes its close. 534 00:51:51,4 --> 00:51:58,44 Then you realize maybe I made a mistake, and you … It’s all happening also personally, 535 00:51:58,45 --> 00:52:01,9 but within a community of researchers who’s trying to find this. 536 00:52:02,54 --> 00:52:08,21 You criticize the ideas of others, and others criticize your ideas and this way you make progress. 537 00:52:08,55 --> 00:52:10,65 Because it’s a difficult problem 538 00:52:10,65 --> 00:52:20,11 and you need the … You need insights from many people that know different aspects of theoretical phases of physics in 539 00:52:20,11 --> 00:52:22,03 general and can inform this. 540 00:52:22,03 --> 00:52:32,29 Interviewer: Is it possible to think of something like an entity who is on the other side of this frontier?. 541 00:52:29,67 --> 00:52:32,16 Or, maybe not an entity but [crosstalk 00:52:33] 542 00:52:32,29 --> 00:52:36,5 Juan Maldacena: Well, there might be another intelligence in our universe who has already figured out this. 543 00:52:36,5 --> 00:52:43,65 He has figured this out, and has understood these problems. At least it’s not known to us. 544 00:52:43,65 --> 00:52:58,84 Interviewer: When you are on the frontier like the west was [won 00:52:58] here in the United States. 545 00:52:59,12 --> 00:53:02,23 You don’t know what’s out there, but you go there and you find things. 546 00:53:03,77 --> 00:53:10,58 It’s because you didn’t know that there were Indians, and there was another Coast and another ocean. 547 00:53:10,58 --> 00:53:17,09 There is some awareness on the other side of the frontier. Only we don’t know. 548 00:53:17,21 --> 00:53:20,75 What kind of awareness is on the other side of your frontier? 549 00:53:20,75 --> 00:53:23,66 Juan Maldacena: Well, by awareness you mean the Indians. 550 00:53:23,66 --> 00:53:30,09 Well, you’re putting too many anthropomorphical things that were not present in this discussion. 551 00:53:31,32 --> 00:53:38,96 We only known intelligence in the universe, only known being that is trying to understand the universe. 552 00:53:38,96 --> 00:53:40,62 We are just expanding. 553 00:53:41,69 --> 00:53:43,17 When I say expanding the frontier, 554 00:53:43,17 --> 00:53:47,46 it’s just understanding the questions that they’re understanding laws of physics better. 555 00:53:47,46 --> 00:53:50,08 These entities are very simple things. 556 00:53:50,23 --> 00:53:54,58 One of the features of physics is that I think is amazingly interesting, 557 00:53:55,06 --> 00:53:58,32 is how simple the fundamental physics laws are. 558 00:53:58,32 --> 00:54:05,25 Of course you might say, if it takes a couple of years to understand it, and you need to study or maybe more, 559 00:54:05,25 --> 00:54:08,02 maybe you need to understand, study physics for five years to understand. 560 00:54:08,02 --> 00:54:08,41 Then, 561 00:54:08,41 --> 00:54:13,63 why are you saying they are simple? They are simple in the sense that the actual laws that govern the emotional zone, 562 00:54:13,63 --> 00:54:20,79 are really simple. You don’t have to come up with rules and lots of books and so on. 563 00:54:20,79 --> 00:54:27,47 It’s been very different than the laws that you find in the senators, 564 00:54:27,47 --> 00:54:32,00 and people produce where there are exceptions here and there. 565 00:54:33,84 --> 00:54:40,00 Here there’s a very simple statement, and this is followed by everything we know. 566 00:54:40,00 --> 00:54:40,71 Interviewer: It’s true? 567 00:54:40,71 --> 00:54:45,65 Juan Maldacena: It’s true to the extent that we’ve been able to experimentally verify, 568 00:54:47,21 --> 00:54:53,47 and the statements have simple learning language which is unfamiliar. A language which takes a long time to learn. 569 00:54:53,69 --> 00:55:03,33 That’s what takes a long time. It’s just to learn this language in which the formula is the laws.. 570 00:54:58,55 --> 00:55:03,27 Once the laws are formulated, they’re in a very simple way. Once you [crosstalk 00:55:04] 571 00:55:03,33 --> 00:55:04,73 Interviewer: Which one do you like the most? 572 00:55:04,73 --> 00:55:08,97 Juan Maldacena: Well, I think the general relativity is the most beautiful theory. 573 00:55:09,42 --> 00:55:16,64 Because it translates physics into geometry. This is a very nice theory. 574 00:55:16,64 --> 00:55:27,86 We don’t know how to make such a beautiful theory out of quantum mechanics. Maybe it will exist at some point. 575 00:55:27,86 --> 00:55:38,82 Interviewer: For you as a child for example, what led to this position you have right now on this frontier? 576 00:55:38,82 --> 00:55:40,41 Where did it start? 577 00:55:40,41 --> 00:55:47,02 Juan Maldacena: Well, as a child I was watching my father for example fixing the washing machine, 578 00:55:47,27 --> 00:55:56,32 and trying to learn how to do it myself. Again, understanding how everyday objects work. 579 00:55:56,32 --> 00:56:01,34 Like the washing machine, the car, the radio and so on. 580 00:56:01,34 --> 00:56:08,42 You learn a little bit about technology and how technology exploits the laws of physics. 581 00:56:08,83 --> 00:56:21,08 That got me interested in understanding the laws of physics which underlie technology. Seeing how far they understood.. 582 00:56:17,27 --> 00:56:21,06 What things are known, what things are not known, and [crosstalk 00:56:22] 583 00:56:21,08 --> 00:56:22,72 Interviewer: How did you do that as a child? 584 00:56:22,72 --> 00:56:27,83 Juan Maldacena: Well, as a child I was mostly interested in technology and how things worked. 585 00:56:27,83 --> 00:56:36,1 Then, when I was in high school I got a little more interested in the laws of physics and chemistry. 586 00:56:35,5 --> 00:56:35,9 and [crosstalk 00:56:37] 587 00:56:36,1 --> 00:56:40,05 Interviewer: What did you do to explore as a child? 588 00:56:40,05 --> 00:56:48,83 Juan Maldacena: Mainly taking things apart and seeing how they worked. That’s basically the process. 589 00:56:48,83 --> 00:56:50,08 Interviewer: Yeah? Putting them together again? 590 00:56:50,08 --> 00:56:52,61 Juan Maldacena: Yeah. I was taking them apart, putting them together. 591 00:56:52,96 --> 00:56:56,38 Just learning how to fix the household appliances. 592 00:56:56,38 --> 00:57:09,91 Interviewer: That’s practical. I mean, if you try to find out how it’s made and why it works. Of course, I guess? 593 00:57:09,91 --> 00:57:15,58 Juan Maldacena: Right. I was always curious in understanding how things work. I mean, how does a TV work? 594 00:57:15,58 --> 00:57:21,26 How does a radio work? What’s the actual principle it uses. 595 00:57:21,26 --> 00:57:22,88 Interviewer: Do you know now? 596 00:57:22,88 --> 00:57:30,55 Juan Maldacena: Yeah. I think I know the basics. I wouldn’t know all the details.. 597 00:57:27,34 --> 00:57:30,22 I guess the technology which I again [crosstalk 00:57:30] 598 00:57:30,55 --> 00:57:40,36 Interviewer: You know, you can … You know how a television works because you understand the physics inside? 599 00:57:40,36 --> 00:57:52,15 Or is it like comparing it to the laws of physics? 600 00:57:52,15 --> 00:57:58,1 Juan Maldacena: Well, the TV or any simple … Any machine, 601 00:57:59,02 --> 00:58:02,82 even simpler perhaps is better to think out the simpler machine first. 602 00:58:02,98 --> 00:58:07,78 Has different parts, and they work together to … Each part is there for a reason, 603 00:58:08,32 --> 00:58:19,18 and they work together to make the machine work. 604 00:58:19,18 --> 00:58:22,18 Most of our everyday machines are … Television is made out of electronic circuits. 605 00:58:22,18 --> 00:58:34,27 They’ll move currents around, and they do … They show the light on the screen and so on.. 606 00:58:29,83 --> 00:58:33,97 That makes a television work, and you have to understand how this [crosstalk 00:58:35] 607 00:58:34,27 --> 00:58:38,54 Interviewer: Does a child who was your age did that? 608 00:58:38,54 --> 00:58:45,25 Juan Maldacena: Well, maybe I was perhaps from eight to 12 would be doing this thing of taking machines apart 609 00:58:45,25 --> 00:58:47,42 and putting them together 610 00:58:47,42 --> 00:58:51,95 Interviewer: What did your parents say about that? Don’t do it again? 611 00:58:51,95 --> 00:58:57,1 Juan Maldacena: No. My dad liked to do this himself, so. 612 00:58:57,1 --> 00:58:59,29 Interviewer: Taking things apart you learned from your father? 613 00:58:59,29 --> 00:59:01,69 Juan Maldacena: Yeah. That’s right.. 614 00:59:00,34 --> 00:59:01,35 Interviewer: What [crosstalk 00:59:02] 615 00:59:01,69 --> 00:59:10,25 Juan Maldacena: My mother liked to give things fixed, so. My dad always liked to fix things. 616 00:59:10,25 --> 00:59:14,5 He was very practical, and he liked the challenge of fixing. 617 00:59:14,5 --> 00:59:14,64 Sometimes, 618 00:59:14,64 --> 00:59:22,46 you don’t know how it works so it’s nice to have to fix something that you don’t know exactly how it works.. 619 00:59:19,82 --> 00:59:22,4 Then you manage to understand how it works [crosstalk 00:59:23] 620 00:59:22,46 --> 00:59:26,51 Interviewer: When you are on the road, and your car has a problem you can fix it? 621 00:59:26,51 --> 00:59:33,63 Juan Maldacena: Well, I was able to do that in the past. Now, cars got more complicated. I don’t know. 622 00:59:33,75 --> 00:59:37,68 This car hasn’t broken down recently, so I can’t tell for sure. 623 00:59:37,68 --> 00:59:48,7 Interviewer: It all started at a young age, and it’s almost you inherited from your father. 624 00:59:50,98 --> 00:59:52,55 Now you are here at Princeton Advanced Studies Institute. 625 00:59:52,63 --> 01:00:08,57 In a position where you are allowed to think as much as you can? 626 01:00:08,57 --> 01:00:14,14 Juan Maldacena: Right. I’m encouraged to think and do research all the time. 627 01:00:14,14 --> 01:00:21,33 Interviewer: Is it too simple to say that your job is thinking? 628 01:00:21,33 --> 01:00:23,66 Juan Maldacena: Yeah. It’s thinking. It’s discussing. 629 01:00:23,66 --> 01:00:30,71 Its learning what other people are thinking and reading what other people write. Trying to make a progress. 630 01:00:30,71 --> 01:00:31,64 Interviewer: Are you thinking all the time? 631 01:00:31,64 --> 01:00:38,51 Juan Maldacena: Well, I mean no. I’m reading what other people write. 632 01:00:38,51 --> 01:00:48,48 I’m listening to other people’s ideas and presentations, and discussing with my colleagues.. 633 01:00:45,62 --> 01:00:48,14 We are writing formulas, and [crosstalk 01:00:51] 634 01:00:48,48 --> 01:00:56,85 Interviewer: Can you decide, now I start thinking? Or does it happen? Or, how does it work? This thinking process. 635 01:00:56,85 --> 01:01:04,44 Juan Maldacena: I guess the thinking normally you try to … This problem sounds very vague and grand. 636 01:01:04,61 --> 01:01:08,01 We try to think on very concrete problems where we can make progress. 637 01:01:08,01 --> 01:01:12,61 There are the questions that are extremely interesting, but almost impossible to solve. 638 01:01:12,61 --> 01:01:15,99 There are questions which are perhaps too easy to solve. We try to be in between. 639 01:01:16,09 --> 01:01:20,56 Try to find the most difficult or interesting questions that you can actually say something useful about. 640 01:01:20,56 --> 01:01:24,94 Lots of thinking is trying to focus on such questions. 641 01:01:24,94 --> 01:01:31,6 Try to imagine very simple toy models, or simple models where we can say something new. 642 01:01:31,6 --> 01:01:37,32 Interviewer: Maybe a few easy answers together might solve a more difficult answer? 643 01:01:37,32 --> 01:01:41,07 Juan Maldacena: Yeah. This thing that I was saying before. You do a step at a time. 644 01:01:41,23 --> 01:01:43,5 We have to figure out where we do the next step. 645 01:01:43,75 --> 01:01:48,1 Next step is in something we more or less know, but moves us in the right direction. 646 01:01:48,65 --> 01:01:52,58 From which we can get a better view of what the next step would be. 647 01:01:52,58 --> 01:02:00,94 Interviewer: When do you do your best thinking?. 648 01:01:55,94 --> 01:02:04,08 Juan Maldacena: Well, I think during the day and [crosstalk 01:02:03]. 649 01:02:00,94 --> 01:02:07,7 Interviewer: Is all that you are the way [inaudible 01:02:04] For example, when you’re outside, or. 650 01:02:06,79 --> 01:02:07,58 when you’re in the shower [crosstalk 01:02:10] 651 01:02:07,7 --> 01:02:12,88 Juan Maldacena: It’s mostly I would say in my office, talking to other people. 652 01:02:14,11 --> 01:02:25,08 Normally when you talk to other people, you get new ideas. 653 01:02:20,12 --> 01:02:24,83 and usually many times ideas come together in this [crosstalk 01:02:25] 654 01:02:25,08 --> 01:02:30,81 Interviewer: Those colleagues are gone and then you have to write down the idea?. 655 01:02:29,03 --> 01:02:30,47 Or, do you have to [crosstalk 01:02:32] 656 01:02:30,81 --> 01:02:38,2 Juan Maldacena: We write them together, and we certainly write articles with other people. This is important. 657 01:02:38,71 --> 01:02:42,8 Most of my … Are with other people. We are collaborators. 658 01:02:42,8 --> 01:02:57,3 Interviewer: Yes. Once someone said it’s hard to sit. It’s hard to sit and not to think. 659 01:02:57,3 --> 01:03:03,96 It’s so hard to shut down your thinking. How do you think about that? 660 01:03:03,96 --> 01:03:04,96 Juan Maldacena: Well, 661 01:03:04,96 --> 01:03:10,99 it’s something … I guess you have to be a little obsessive sometimes to work on these problems. 662 01:03:11,23 --> 01:03:14,59 Because you want to think of these problems and you have to know other things. 663 01:03:14,59 --> 01:03:18,76 It’s easy to get distracted and think about something else. When you’re not making progress. 664 01:03:18,76 --> 01:03:25,38 If you’re trying to solve a problem and you’re not making progress, it’s easy to get distracted. 665 01:03:25,38 --> 01:03:31,66 Sometimes you need to keep trying to find solutions to that problem you initially set out to do. 666 01:03:31,66 --> 01:03:35,64 Being slightly obsessive about it. Then you can make some progress. 667 01:03:35,64 --> 01:03:36,94 Interviewer: You are obsessive? 668 01:03:36,94 --> 01:03:41,07 Juan Maldacena: Slightly, yeah. 669 01:03:41,07 --> 01:03:46,81 Interviewer: When there’s something distractive, what is your distraction? 670 01:03:46,81 --> 01:03:54,56 Juan Maldacena: Well, it could be some other interesting idea in some other slightly different field. 671 01:03:54,56 --> 01:04:06,57 Sometimes it’s good to be distracted. Maybe the problem you’re trying to solve was bad, and so it’s a balance. 672 01:04:06,57 --> 01:04:16,14 Interviewer: Or, you can say this is what you’re good at, and you make progress and solutions or answers. 673 01:04:16,14 --> 01:04:31,83 Is there also an area in which you are able to find the answers? The opposite of your talent? 674 01:04:31,83 --> 01:04:49,75 Juan Maldacena: Yeah. I’m not sure. Fashion.. 675 01:04:43,14 --> 01:04:49,42 Interviewer: Yeah. You cannot describe that into one [crosstalk 01:04:50] 676 01:04:49,75 --> 01:04:51,09 Juan Maldacena: That’s right. 677 01:04:51,09 --> 01:04:56,17 Interviewer: I mean in your character. 678 01:04:56,17 --> 01:05:04,02 If you are obsessive in finding answers in this theoretical field, but it’s also 679 01:05:04,02 --> 01:05:18,09 when you find it you can write it down in one line. Then it’s true.. 680 01:05:09,09 --> 01:05:17,9 Unlike political laws with all the kinds of … What is the area in which [crosstalk 01:05:17] 681 01:05:18,09 --> 01:05:21,86 Juan Maldacena: I think the process is not that you write down a formula and then it is true. 682 01:05:21,86 --> 01:05:30,01 Normally in physics, the process is that for some physical theory to be true, you have to be compared to experiment.. 683 01:05:28,34 --> 01:05:29,68 Interviewer: I’m sorry [crosstalk 01:05:30] 684 01:05:30,01 --> 01:05:36,16 Juan Maldacena: It’s checked against experiment. Then we become more sure that it’s probably true. 685 01:05:36,16 --> 01:05:39,46 Can always be some other experiment that contradicts it. 686 01:05:40,02 --> 01:05:47,57 As many experiments that agree with it, you feel more and more confident.. 687 01:05:43,18 --> 01:05:48,81 Interviewer: Yeah. I’m sorry to say that, then I say that it’s true [crosstalk 01:05:47] They agree on it. 688 01:05:48,81 --> 01:05:49,55 Juan Maldacena: Yeah. 689 01:05:50,04 --> 01:06:00,85 Many times … A lot of our work sometimes is to … There are some mathematical relations like … The reason for this 690 01:06:00,85 --> 01:06:08,09 is that some of our work is mathematics, is because the laws of physics are written in this mathematical language. 691 01:06:09,01 --> 01:06:16,38 Sometimes even laws which are in principle simple like this equations of Einstein, which are simple to write down, 692 01:06:16,38 --> 01:06:18,95 but they’re very difficult to solve. 693 01:06:18,95 --> 01:06:27,67 You need your computers, and with time engineers, ideas to solve the questions, 694 01:06:27,67 --> 01:06:31,78 and …Once you find for example some solution of the equation, you can check that it is the solution. 695 01:06:31,78 --> 01:06:38,92 Then it becomes a true solution. That’s an example way. That’s where you could say, well its mathematics. 696 01:06:38,92 --> 01:06:43,2 It’s within the … If you assume the questions are the correct description of physics, 697 01:06:43,49 --> 01:06:45,36 this is a solution of the equations. 698 01:06:45,36 --> 01:06:48,72 Interviewer: Correct me if I’m wrong, 699 01:06:48,99 --> 01:06:56,41 but mathematics is like an instrument for you to understand what you need to understand. What you want to understand? 700 01:06:56,41 --> 01:07:00,7 Juan Maldacena: Exactly. Before we were talking about the language in which these laws are written. 701 01:07:00,82 --> 01:07:07,9 This is a language that is fairly mathematical.. 702 01:07:04,32 --> 01:07:07,66 You need to know enough mathematics to be able to understand the [crosstalk 01:07:08] 703 01:07:07,9 --> 01:07:13,98 Interviewer: I can imagine that this mathematics, you are talented for using it. 704 01:07:15,26 --> 01:07:21,17 It’s a way to look around you and follow your obsession. 705 01:07:22,04 --> 01:07:29,11 There are also very much a lot of areas in which mathematics just doesn’t work. 706 01:07:30,47 --> 01:07:40,52 Then you … Which areas are that, that you cannot use math? 707 01:07:40,52 --> 01:07:45,17 Juan Maldacena: There are many areas I really like where we don’t necessarily use math. 708 01:07:45,17 --> 01:07:50,16 If I want to learn the piano, math is not very useful. 709 01:07:50,16 --> 01:07:56,93 Or if I want to play soccer, I learned to play soccer but math is not very useful. 710 01:07:56,93 --> 01:07:58,2 You just have to practice playing soccer. 711 01:07:58,52 --> 01:08:08,22 If I want to cook [data 01:08::01] in my lunch or cook a nice meal, math is also not very useful.. 712 01:08:06,21 --> 01:08:08,01 There are lots of areas but [crosstalk 01:08:08] 713 01:08:08,22 --> 01:08:11,76 Interviewer: What are the things which you are not good at? 714 01:08:11,76 --> 01:08:17,95 Juan Maldacena: Playing soccer, and sports. 715 01:08:17,95 --> 01:08:20,92 Interviewer: Do you like it? 716 01:08:20,92 --> 01:08:22,92 Juan Maldacena: I do it sometimes. 717 01:08:22,92 --> 01:08:31,25 Interviewer: Is that an aspect of mathematics as well? That you can like it? 718 01:08:31,25 --> 01:08:36,16 Juan Maldacena: If I like mathematics because of some aspect? 719 01:08:36,16 --> 01:08:43,32 I like some aspects of mathematics because first it’s a nice tool to describe physics and, 720 01:08:44,25 --> 01:08:47,17 I certainly like it’s interesting. 721 01:08:47,17 --> 01:08:53,24 While mathematics is also a subject on its own and it’s huge, I know a little bit of mathematics, 722 01:08:53,24 --> 01:08:57,43 and I write down the mathematics I think would be useful for this problem. 723 01:08:59,53 --> 01:09:05,1 Sometimes people need to learn, invent some new mathematics to solve these problems. 724 01:09:05,1 --> 01:09:15,69 Interviewer: Yeah. For example, I’m much more comfortable when I talk to people, trying to understand people. 725 01:09:17,44 --> 01:09:20,96 I’m not comfortable when I talk with other people about mathematics. 726 01:09:21,71 --> 01:09:32,98 Because it’s not my thing, or my talent, or … I choose the things in which I’m comfortable, 727 01:09:33,32 --> 01:09:34,92 and that’s what I’m doing right now. 728 01:09:34,92 --> 01:09:39,86 I’m [firmly 01:09:36] interviewing people, trying to have that person at work. 729 01:09:39,86 --> 01:09:43,56 Juan Maldacena: Right. That’s true. 730 01:09:44,35 --> 01:09:51,41 We all know what our strengths are, and we try to do an activity where we can really use our talents. 731 01:09:51,41 --> 01:09:59,12 Yeah, certainly I would be a very bad interviewer. To know what the other person is thinking or trying to guess it. 732 01:09:59,12 --> 01:10:02,12 Yeah, we all do these various talents. 733 01:10:04,31 --> 01:10:11,5 Our natural … Well, we develop some talents and I guess through part of our lives, we continue developing them 734 01:10:11,51 --> 01:10:13,72 and we get better at those areas. 735 01:10:13,72 --> 01:10:28,27 Interviewer: Anna, told me about … Because I don’t want to forget that one. 736 01:10:29,48 --> 01:10:37,85 Two stories she told about the mountain and a valley, and about Romeo and Juliet. 737 01:10:37,85 --> 01:10:41,54 Juan Maldacena: Okay. 738 01:10:41,54 --> 01:10:52,49 Interviewer: Do you think it’s interesting to tell that? For understanding your theory? 739 01:10:52,49 --> 01:10:56,92 Juan Maldacena: Yeah. I’m trying to remember what the story about the mountain and the valley was. 740 01:10:56,92 --> 01:11:06,12 Interviewer: That if you live in a mountain … a valley,. 741 01:11:01,27 --> 01:11:05,96 and you have no reason to go up on the mountain because you cannot go [crosstalk 01:11:07] 742 01:11:06,12 --> 01:11:12,59 Juan Maldacena: Oh, yeah. This was … I think the original question was, was this useful for anything? 743 01:11:12,59 --> 01:11:19,53 Or, what are the technological applications of this research, or this area of research? 744 01:11:22,43 --> 01:11:27,04 This area of research doesn’t have a direct technological application that we know of. 745 01:11:29,76 --> 01:11:33,22 We do it because we want to know wand we want to understand. 746 01:11:34,49 --> 01:11:39,46 An analogy is that to think that we have, let’s say, a town that lives in a valley. 747 01:11:39,46 --> 01:11:44,23 The valley’s fertile and they grow corn, and their grow food in the valley. 748 01:11:44,23 --> 01:11:49,34 There’s a nearby mountain and there’s mountains surrounding the valley. 749 01:11:49,82 --> 01:11:56,19 Someone might decide to go up the mountain just to see what’s there. The expedition of going up the mountain might be 750 01:11:56,19 --> 01:12:01,65 totally useless for growing better corn, or you’ll not plant anything nice in the mountains. 751 01:12:01,65 --> 01:12:07,74 Certainly going up the mountain might give you better view of the valley. 752 01:12:07,74 --> 01:12:12,61 Might help you understand where this valley is located. It might allow you to see another valley. 753 01:12:13,11 --> 01:12:16,51 This is not guaranteed. Maybe there are all mountains, and there are no other valleys. 754 01:12:16,51 --> 01:12:21,4 It’s certainly part of the curiosity of seeing where we are, 755 01:12:21,54 --> 01:12:32,19 and to extend the frontier to really understand better where we are sitting in the universe. 756 01:12:32,19 --> 01:12:36,21 This is one direction in which we can go and certainly that’s where we … I mean, 757 01:12:36,45 --> 01:12:39,27 it’s like a mountain that it’s there. We’re trying to go to the summit 758 01:12:39,27 --> 01:12:49,24 and try to understand the summit is understanding the big bang singularity.. 759 01:12:43,36 --> 01:12:49,14 Is understanding the beginning of the big bang. I will try to climb this mountain the whole way. [crosstalk 01:12:50] 760 01:12:49,24 --> 01:12:52,84 Interviewer: Are you on the mountain? 761 01:12:52,84 --> 01:12:55,32 Juan Maldacena: Well, we don’t know. Because we don’t have a view of the mountain from outside. 762 01:12:55,32 --> 01:13:00,02 We only know that we are climbing. I think we are confident we are climbing. We are not going down. 763 01:13:00,02 --> 01:13:02,02 There must be a summit. 764 01:13:02,02 --> 01:13:03,69 Interviewer: It’s a nice one.