Quantum physicist Juan Maldacena on the new quantum-reality theory (21-02-2016)

Juan Maldacena, a quantum physicist at the Institute of Advanced Study (IAS), on a new quantum-reality theory. He is often called 'the new Einstein'.

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What is your field of research? (00:00:00)
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Everything is build from the small number of particles? (00:02:53)
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The speed of light is constant, time is not? (00:07:33)
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How did the universe form? (00:09:37)
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What happens when you connect these theories? (00:16:33)
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Why do you yourself ask these questions? (00:20:14)
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Are you sure you are going to find the answers? (00:22:16)
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How do you make people understand these theories, since it is so difficult? (00:24:04)
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For a lot of people string theory is not understandable? (00:25:23)
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What makes a physical theory true? (00:26:34)
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What is meant by string theory? (00:27:42)
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Are you researching a theory of your own? (00:29:04)
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Can you explain how a hologram works? (00:31:05)
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Can you call it your lifework? (00:36:39)
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Can your explain things like time, space...? (00:43:48)
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Why do you want to have an explanation for how life started? (00:47:55)
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How do you deal with nearly impossible questions?  (00:49:02)
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When did you ask yourself this question for the first time? (00:50:03)
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Who challenges you to find the answers? (00:51:21)
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What kind of awareness is there on the other side of your frontier? (00:52:50)
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For you as a child, where did it all start? (00:55:28)
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What did you do to explore as a child? (00:56:36)
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What did your parents say about it? (00:58:46)
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Your job is thinking...? (00:59:38)
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How does your thinking process works? (01:00:50)
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Is it hard to stop thinking? (01:02:47)
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What do you do when you're not working? (01:03:40)
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Mathematics is like an instrument to you? (01:06:47)
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What are the things you are not good at? (01:08:08)
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What's the story about The Valley and Romeo and Julia? (01:10:22)
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00:00:00 Interviewer: I will ask a lot of questions, but I prefer it to be like a conversation, so interrupt me if you like.
00:00:14 Juan Maldacena: Right, good.
00:00:16 Interviewer: The first thing, can you introduce yourself?
00:00:18 Juan Maldacena: Yeah, I'm Juan Maldacena, I'm the Carl Feinberg professor here at the Institute for Advanced Study.
00:00:22 Interviewer: What exactly is your field of research?
00:00:28 Juan Maldacena: My field of research is in trying to understand the fundamental laws of nature,
00:00:33 trying to develop theories that connect space-time and quantum mechanics,
00:00:39 and the main objective is to understand the beginning of the Big Bang.
00:00:43 Interviewer: Well, that's a big question.
00:00:48 Juan Maldacena: Yeah.
00:00:48 Interviewer: Did you say the laws of nature?
00:00:50 Juan Maldacena: Yeah. Physics is about studying the laws of nature, so how nature works.
00:00:56 Through the years we've learned a lot about how nature works,
00:01:00 and currently we have theories that are incredibly successful.
00:01:05 One of the theories is the theory that describes gravity.
00:01:08 It was originally developed by Newton, and then improved by Einstein.
00:01:12 Einstein gave us the current equations that govern the behavior of space-time.
00:01:19 We'll discuss perhaps a bit more about what space-time is made of,
00:01:23 or what the theory of Einstein tells us about space-time. That's one very successful theory.
00:01:29 It explained things like the expansion of the universe, the formation of black holes..
00:01:36 Its phenomena that before the theory was introduced, were ..
00:01:39 People didn't even think about them. On the other hand we the whole set of theories that describe matter,
00:01:54 the behavior of matter and the structure of matter.
00:01:57 These theories were rational,
00:01:57 especially rational quantum mechanical study being developed in the beginning of the 20th century.
00:02:03 The quantum is very important for the description of matter.
00:02:08 It's what keeps matter stable and prevents it from collapsing. Prevents atoms from collapsing, and so on.
00:02:15 This theory, well, it was further developed through the 20th century
00:02:20 and it's now come to what we call the standard model of particle physics.
00:02:26 Interviewer: Particle physics.
00:02:28 Juan Maldacena: It's basically the basic structures, the basic constituents of matter.
00:02:33 Matter is made out of little, small particles that behave according to the so-called quantum mechanics.
00:02:42 What is remarkable is that this list of constituents is very small.
00:02:46 So a very small number of particles make up all the matter that we see.
00:02:51 Interviewer: Really? So everything is built up from just a small number of particles?
00:02:58 Juan Maldacena: Yes, small number of kinds of particles.
00:03:01 We have the particles, the electron is one of them, and then we have the particles that make up the nuclei,
00:03:09 the nuclei of the atom. Within the nuclei are some particles called quarks, but they are small, little particles.
00:03:14 For most of matter they are made out of just two kinds, so-called up and down quark.
00:03:21 Then there are some particles that mediate the forces within them. The photon, electromagnetic waves, and so on.
00:03:28 Then the weak force and the strong force.
00:03:32 The strong force keeps the nucleus together, and with these particles and these forces we can describe all of matter.
00:03:39 Interviewer: You know that, or you think so?
00:03:42 Juan Maldacena: No, well we know it experimentally,
00:03:46 and the latest experiment was the experiment in the large hydro collider, which discovered the so-called Higgs boson,
00:03:56 which was one of the missing particles in the standard model.
00:04:00 Now we have whole set of particles that describes everything.
00:04:04 I briefly told you about the particles that make up most all named matter,
00:04:08 but there are other unstable particles which are similar, but the structure gets replicated a few times,
00:04:17 and while so now we have a complete set of particles with a logically consistent theory that uses the structure of
00:04:25 something called relativistic quantum mechanics.
00:04:28 [crosstalk 00:04:30] Relativistic quantum mechanics,
00:04:30 there's quantum mechanics plus the principle of special relativity. We can discuss perhaps special relativity a little
00:04:37 more. Let me discuss perhaps these theories a little more.
00:04:44 Interviewer: Yes, that's okay.
00:04:45 Juan Maldacena: Then I can go on into discussing perhaps the more current issues.
00:04:53 First, well we have these notions of space and time. Right?
00:04:59 In principle space and time seem totally disconnected from each other..
00:05:02 The very intuitive notion of space, while time looks a little more mysterious to us, and a bit ..
00:05:09 Certainly different from space.
00:05:12 The first point I'd like to explain is why physicists talk about space-time, why they put these two words together.
00:05:18 Why don't they talk about space temperature, space I don't know. Price of [solar 00:05:27] or whatever.
00:05:25 They talk about these two things because the way you perceive time depends on how you are moving through space. If you
00:05:36 have two observers moving relative to each other, the two observers perceive time differently.
00:05:44 If you have a clock here, another clock that is moving,
00:05:48 the second clock will appear to this observer as moving slower than the clock here that's at rest.
00:05:54 The other observer will see the other clock also moving slower.
00:05:58 This can happen because space and time sort of get mixed by motion.
00:06:06 This is the consequence of a principle, which is the principle that light,
00:06:13 the speed of light is constant for these two observers. This is something that is not totally intuitive.
00:06:20 You have one observer that is stationary and you have a light beam that travels this way,
00:06:25 and you have another observer that moves in this direction, naively,
00:06:30 according to your intuition you will expect that this observer should see the light moving slower. Right?
00:06:35 If instead of talking about the light beam we were talking about the train, that would be the case.
00:06:42 But it turns out that experimentally the speed of light is constant, so it is the same for all observers.
00:06:50 Interviewer: Oh really, so compared to the train?
00:06:53 Juan Maldacena: Yes, so if instead of a train we had a beam of light, the two observers,
00:07:00 one is stationary the other is moving, both would see the light going at the same speed,..
00:07:04 so the light would be moving this way .. This happens because the rate of ..
00:07:12 How time and space are perceived by the two observers are different.
00:07:16 The price you have to pay for this constancy of the speed of light is that time is now relative.
00:07:22 In the theory of relativity the speed of light is absolute, but time is relative.
00:07:28 Time is relative to who's measuring it.
00:07:32 Interviewer: I can try to understand what you are saying. What I hear is that you say the speed of light is constant.
00:07:46 So time is not constant.
00:07:52 Juan Maldacena: Right, time is relative.
00:07:55 The flow of time depends on how you are moving through space-time, so it's similar to let's say space, right?
00:08:03 So we are standing in space, there is some direction we call forward and some direction we call go right.
00:08:11 But if you have another person who's looking in a different direction what's forward to him
00:08:15 and what's to the right is different. So it's exactly the same but for two moving observers.
00:08:21 You have two moving observers but one calls time and space is different from what the other calls time and space.
00:08:29 That's why is more convenient to think about space-time as something that's both time and space,
00:08:37 and that thing is the same for both.
00:08:41 What one calls time and space is different,
00:08:44 but space-time is the same. It's the universal structure in which particles move.
00:08:57 The laws of physics have to have this symmetry of the constancy of speed of light
00:09:05 and the fact that the laws of physics should be independent of how you're moving.
00:09:09 When you combine quantum mechanics and this principle of special relativity,
00:09:15 you get the modern theory of quantum physics.
00:09:17 Well you get the structure, which is called quantum [field 00:09:21] theory,
00:09:21 and used in special cases of the structure, putting in which particles you have and the interactions and so on.
00:09:28 You get the models for particle physics and they are incredibly successful
00:09:32 and they describe all the experiments that you can do..
00:09:36 Interviewer: In the beginning you raised the big question, how did the universe ..
00:09:46 Juan Maldacena: Let me first say a few words about general relativity.
00:09:56 According to our intuition, so space is sort of absolute and there is some [inaudible 00:10:03]
00:10:02 in space where particles move and objects move.
00:10:09 That's probably the theory of [mutant 00:10:13] we learned in school, that planets move and so on.
00:10:14 They are moving in some space that was preexisting and it's not affected at all by the motion of these planets.
00:10:20 But in the theory of [inaudible 00:10:25] what Einstein postulates is that space or space
00:10:29 and time because they have to come together because of the principle of special relativity.
00:10:33 They are actually structured that is dynamic because it can be bent by the presence of matter. He further says that the
00:10:42 force of gravity is due to this bend in our space-time. This is a new, very interesting conceptual idea.
00:10:54 Again, it describes gravity as we see it, and it describes deviations from Newton's gravity.
00:11:01 It describes new things that were not known at the time of Einstein, like the expansion of the universe,
00:11:09 the formation of black holes in extreme circumstances.
00:11:13 Well, some of it's predictions are have now been confirmed, like the discovery of gravity waves, very recently,
00:11:20 just a week ago it was announced.
00:11:23 Interviewer: Yeah, I saw that, were you excited about it.
00:11:25 Juan Maldacena: Yeah, that's really exciting, very interesting.
00:11:28 Interviewer: Did you know about that they were going to announce this?
00:11:33 Juan Maldacena: Yeah, there were rumors that they were going to announce it.
00:11:37 Of course the experiment had been going for a couple of decades.
00:11:42 Interviewer: For a couple of billion years.
00:11:45 Juan Maldacena: Well, the gravity waves were going on for a long time,
00:11:49 but the the experiments trying to detect them also took a lot of effort.
00:11:54 We're getting [dramatic 00:11:57] confirmation of both Einstein's theories.
00:12:00 Moreover, the [seasons 00:12:02] of black holes.
00:12:03 This theory of special relativity of general relativity, well Einstein the other equations,
00:12:09 but then there was a lot of research trying to understand the solutions of equations.
00:12:13 The physical interpretation of the solutions. For example, black holes were really only understood in the ‘60s.
00:12:24 Even theoretically.
00:12:24 Then understanding them better then led to understanding what things you should look for in the sky,
00:12:29 and some objects in the sky were recognized as probably endings of black holes,
00:12:35 and now we have this guy with the world detection which appears to come from the coalition of two black holes.
00:12:43 Interviewer: You think so?
00:12:46 Juan Maldacena: That’s a model to describe it. The only announce one coalition.
00:12:53 Probably they see more, it will become more and more convincing..
00:12:59 Interviewer: Yeah. Because this is the first one. It’s a question of time that more of this [crosstalk 00:13:04]
00:13:03 Juan Maldacena: You would hope.
00:13:05 Interviewer: Yeah.
00:13:06 Juan Maldacena: That’s all about Einstein theory of relativity.
00:13:11 Einstein theory of general relativity is a theory where space time is dynamical. It’s something that moves.
00:13:16 It’s not the starting thing. It’s an actor in physics. It’s not the stage in which physics happens.
00:13:24 It is the stage for all particle physics. For all the matter and so on.
00:13:29 You have the space time and then matter moves in that space time.
00:13:32 Also space time reacts to the presence of matter, and it moves itself.
00:13:39 Through cosmology, this expansion of the space time is very important.
00:13:44 Space time expands and it cools because of that expansion.
00:13:47 Expansion of space time is very important for getting to the universe.
00:13:53 What it is and structure of matter to what it is. This expansion is important for cooling the universe
00:13:59 and then further the force of gravity creates the structures that we have in the universe.
00:14:04 Such as galaxies and planets and so on. It’s important for explaining nature as we said..
00:14:13 Theory of relativity in some sense is incomplete. Because it [crosstalk 00:14:21]
00:14:20 Interviewer: Incomplete?
00:14:21 Juan Maldacena: Incomplete.
00:14:26 In the sense that if you start out with some initial conditions which are reasonable, the system evolves
00:14:33 and creates so called singularities. You can solve the equations.
00:14:37 You find situations where the curvature of space time becomes infinite.
00:14:41 This happens for example when black hole collapses.
00:14:45 In the interior of the black hole, there’s a region with infinite space time curvature.
00:14:50 Space time becomes so curved, and so … The force of gravity somehow becomes infinite there.
00:14:56 If you were to fall in there, you would be ripped apart.
00:15:04 We don’t have a theory that … The current theory is like general theory
00:15:08 and particle physics do not explain what happens in that situation.
00:15:12 Interviewer: Are you looking for the explanation?
00:15:18 Juan Maldacena: Yeah. Those are the theories we have..
00:15:21 I think maybe we can make a small bit of smile [crosstalk 00:15:25] Maybe I want to tell them to be quiet.
00:15:30 Interviewer: We were at the point that you were trying to connect the theories.
00:15:36 Juan Maldacena: Yeah. The Einstein theory works very well for many, many things we observe.
00:15:43 The equations themselves fail in some situations. One situation is when matter collapses in a black hole.
00:15:49 The interior of the black hole, we got the region with very high curvature.
00:15:55 If you were to fall in there, you would be ripped apart.
00:15:57 The equations don’t allow us to [the eye 00:16:02] what happens to matter when that happens.
00:16:04 Another interesting situation is if you evolve the equations backwards,
00:16:06 and you try to find out what happened in the very beginning of the big bang. Also the current theories don’t explain.
00:16:12 It cannot explain what happened. Again the expansion would be so rapid,
00:16:18 that space expanding so rapidly you couldn’t … You cannot … The eye what happens.
00:16:27 The equations themselves, the curvature becomes infinite, and the equations fail. The reason … Yeah?
00:16:34 Interviewer: If I try to imagine of course what’s happening inside your head trying to connect these theories,
00:16:41 what happens?
00:16:42 Juan Maldacena: The main reason for these inconsistencies is the fact that they … Einstein’s theories so called
00:16:47 Classical Theory, which is a good theory when things are very big.
00:17:00 Basically very short distances, you have to take into account the quantum.
00:17:06 The same way that matter of long distances can be described, also classically.
00:17:09 When you go to short distances, you have to describe it using the quantum mechanical description.
00:17:14 Space time is similar.
00:17:16 When you go to very short distance in space time, you also would need quantum mechanical description.
00:17:22 For matter, when we go to short distances, we go to the atoms, the elementary particles and so on. For space time,.
00:17:28 we should go again to something that will be atoms of space time. I think that the [crosstalk 00:17:35]
00:17:35 Interviewer: What is that?
00:17:35 Juan Maldacena: We think that we went to such a theory, we could do this. We could perhaps understand the big bang..
00:17:42 Or, the situations which we cannot understand [crosstalk 00:17:46]
00:17:45 Interviewer: Define the atoms of space time.
00:17:47 Juan Maldacena: I can’t define the atoms of space time. We’re trying to find what they are.
00:18:02 One idea that is wrong, is the idea that there would be atoms at each different locations in space, and so on.
00:18:08 Space time is not like continuing matter.
00:18:10 Because, one important property that was understood theoretically is that,
00:18:18 when you have the number of configurations in original space time, that number configurations,
00:18:24 does not grow like the volume. As it would with only matter.
00:18:28 The number of atoms somehow wherever they are, of space time,
00:18:31 we know that their number grows like the area of the surface.
00:18:34 Rather than the volume. That’s an interesting property of this so called atoms of space time.
00:18:46 By atoms of space time I mean, well basically vague idea but I try to motivate it in this way.
00:18:53 The search for a theory that describes space time at the quantum mechanical level. Using the laws of quantum mechanics.
00:19:00 The laws of quantum mechanics are laws which are intrinsically probabilistic.
00:19:06 That’s the main difference from the laws of classical physics.
00:19:09 Classical physics, if you know the initial conditions, you can then calculate what would happen in the future..
00:19:16 [crosstalk 00:19:17]
00:19:16 Interviewer: Because you cannot do an experiment you mean?
00:19:18 Juan Maldacena: No, in quantum mechanics you can do experiments.
00:19:21 The results you can prepare the initial conditions always in the same way.
00:19:26 The results of the climates will be different each time you experiment, you’ll get a different answer.
00:19:31 All you can predict according to quantum mechanics is not the precise answer of the experiment,
00:19:39 but the probabilities for the different answers. You do an experiment, it’s like flipping a coin.
00:19:49 You can calculate and you can say, maybe I’ll get 50% one result. 50% of the time one result and 50% the other.
00:19:58 Or maybe it’s 30, 70 and so on. Quantum mechanics allows you to calculate those percentages.
00:20:05 Quantum mechanics doesn’t allow you to give definite answers to some questions. It is intrinsically this way.
00:20:15 Interviewer: That’s a rather big question you ask yourself.
00:20:18 Besides the part that you are this scientist trying to research this.
00:20:26 I’m also interested why is it you asking this question? What’s your … Why do you ask this question?
00:20:39 Why do you do this?
00:20:41 Juan Maldacena: Certainly I’m not the first to ask this question. This question was asked many years ago.
00:20:48 Probably Planck was the first to realize that there was a connection between the quantum and gravity.
00:20:54 At some point gravity would fail, and calculated what distance scale you would [inaudible 00:21:01] was a century ago.
00:21:04 Since then, people have had various ideas by thinking about this problem.
00:21:13 It’s a problem that is hard to access it fundamentally directly.
00:21:17 This distance in which the quantum is important is super tiny.
00:21:20 It’s much smaller than the smallest distances we can see today will accelerate this.
00:21:25 By a group of people who are trying to investigate this from the theoretical point of view,
00:21:36 trying to find the structure of mathematical theory that would put these two things together. We’re trying to do
00:21:43 something similar to what Einstein did when he joined special relativity with Newtonian gravity.
00:21:50 He realize that the theory of Newton was not consistent with this idea that the speed of light is the maximum speed of
00:21:57 propagation of signals. That it should be the same for all observers.
00:22:03 Putting those two things together, he managed to create the structure. The structure of general relativity.
00:22:07 Here we are trying to replicate that from theoretical points of view,.
00:22:11 try to find the connections between the quantum and space time, and [crosstalk 00:22:17].
00:22:15 Interviewer: Are you sure you’re going to find the answers or [crosstalk 00:22:20]
00:22:23 Juan Maldacena: No. We’re not 100% sure, but we’re confident that we have a high probability.
00:22:30 The equation is so interesting, that we should try to investigate it.
00:22:35 Interviewer: You know that you’re on the right path?
00:22:38 Juan Maldacena: Yeah.
00:22:40 What gives us some confidence that we’re in the right path is that, we’re not investigating this in the vacuum
00:22:49 or without … We now have some very concrete theories. The nicest one is the theory of strength theory.
00:22:59 That is a theory based on the construction that works very nicely in some situations.
00:23:05 That manages to join the quantum with space time.
00:23:10 Is a theory under construction, and a theory which is continued to be developed and we’re trying to understand it.
00:23:17 Interviewer: Strength theory.
00:23:18 Juan Maldacena: Yeah. Strength theory. It seems to connect the quantum with space time in a very interesting way.
00:23:24 By investigating strength theory, people have found very interesting mathematical relations. That are true mathematics.
00:23:34 They found the connections between different physical theories.
00:23:38 For example, between the theory of strong interactions and some theories of space time.
00:23:46 The fact that the disconnections were found,,
00:23:49 gives us some confidence that at least the structure that we’re investigating is interesting and [great 00:23:56]
00:23:55 and it could be the answer to this question of quantum gravity.
00:23:59 Which is really the main question we’re trying to answer.
00:24:03 Interviewer: Do you work in a group of people who are on the same level theoretically?
00:24:12 Juan Maldacena: Yeah.
00:24:13 Interviewer: How is it for you to … Now you have to explain it to me, and I don’t understand.
00:24:24 You have to transfer your thoughts or your ideas to people who don’t understand.
00:24:29 Because it’s so difficult even for yourself, it’s difficult. How is that?
00:24:35 Juan Maldacena: Well, for us it’s difficult to find the equations,
00:24:40 but I think what I’m trying to compare is the problem we’re trying to understand
00:24:46 and I think the problem is understandable.
00:24:48 It’s just joining two theories of physics that are out there, and putting them together.
00:24:56 They are not completely compatible with each other.
00:24:58 In the history of physics, when there were two kinds of theories that were not quite compatible,
00:25:02 and you find a structure that puts them together, it might be the right structure.
00:25:06 Interviewer: This theory might be the strength theory?
00:25:09 Juan Maldacena: Yeah. The strength theory is the main tool and the main thing that we’re investigating.
00:25:15 We think that it is not the right structure. It’s probably close to the right structure..
00:25:20 It could be the stepping stone to the right structure. [crosstalk 00:25:25]
00:25:22 Interviewer: For a lot of people, the strength theory is un-understandable,
00:25:26 but you all have to understand this theory just to use it as a possible?
00:25:34 Juan Maldacena: Yeah.
00:25:35 Strength theory might sound complicated,
00:25:38 but it’s something that someone who’s doing his PhD in physics can learn in a year, a couple of years,.
00:25:46 and they can [crosstalk 00:25:47] That’s right...
00:25:53 Interviewer: Maybe [crosstalk 00:25:54] Can you explain to me what [crosstalk 00:25:56]
00:25:55 Juan Maldacena: There is … It’s like playing the piano.
00:25:58 You’re not going to be able to play the piano in five minutes.
00:26:01 Someone can tell you, oh you have to press keys and so on but you won’t be able to play the piano
00:26:08 or to produce nice music.
00:26:08 Interviewer: It sounds awful.
00:26:10 Juan Maldacena: Here also, it takes a while to get familiar. To familiarize yourself with the ideas.
00:26:18 One reason we have this is because you really have to learn a lot of the physics that precedes it.
00:26:24 You have to learn well general relativity, you have to learn well particle theory of interacting particles.
00:26:32 You have to do this.
00:26:34 Interviewer: Isn’t it a fact that if different people from different backgrounds come together
00:26:41 and discuss this strength theory, that in the event that they all know what you’re talking about,
00:26:51 or understand the strength theory, doesn’t make it then true?
00:26:57 Juan Maldacena: No. What makes a physical theory true, as a physics theory of physics is comparison with experiment.
00:27:05 Interviewer: If you all understand the strength theory and then you think it’s true, you understand what it means,
00:27:12 it took some years but different other people took some years and they understand strength theory.
00:27:18 Juan Maldacena: Strength theory today is a mathematical structure.
00:27:21 It’s a mathematical structure which has some physical interpretation.
00:27:26 We don’t yet know whether it’s the right theory of physics.
00:27:28 We think it’s in the right track, and we’re motivated enough to continue stirring it. That doesn’t make it true.
00:27:38 That just makes it a very interesting mathematical theory.
00:27:41 Interviewer: Can you explain to me what is meant by this strength theory?
00:27:45 Juan Maldacena: Well,
00:27:49 mainly strength theory is a theory which some laws that can describe space time at the quantum mechanical level.
00:27:58 Using the laws of quantum mechanics. That it reduces to Einstein theory for big distances. That’s its main advantage.
00:28:09 Now, maybe you are asking why is it called strength.
00:28:12 Well, this comes in the fact that [man 00:28:18] formulation of the theory,
00:28:19 you have little tiny vibrating loops of strength.
00:28:23 Instead of having particles which are point like, as we have in theory of particles, or innate particles,
00:28:32 the elementary objects are a little strengths. One dimension objects.
00:28:37 That’s … Using those,
00:28:41 you can describe ripples of space time interacting. All those gravity waves that we discussed before in the experiment,
00:28:49 when they interact in a quantum mechanical way. They can do so in a way that’s not generating any inconsistency.
00:28:57 Interviewer: Is there a theory of your own which you are investigating or researching?
00:29:09 Juan Maldacena: I’ve been researching some relationship between strength theory and particle physics.
00:29:19 There’s a relationship which is part of this connections that I was describing before.
00:29:24 That the strength theory led to.
00:29:25 This is a connection between theories of gravity in the interior of the space time,
00:29:32 and the theory of particles on the boundary of the space time.
00:29:36 In this relationship, the idea is that the so called atoms of space time in the interior,
00:29:42 are like particles on the boundary. That’s roughly one way to say.
00:29:47 Another analogy people make sometimes is the idea of the hologram.
00:29:51 That you can … A hologram is a two dimensional photographic plate. That when you illuminate it in the light,
00:29:58 you see three dimensional picture.
00:30:00 The idea is that you can have the dynamics of this particle on the boundary or space time so far away.
00:30:08 Can have an alternative description as objects moving in the interior. Subject to the force of gravity.
00:30:15 Interviewer: The atoms of space time are reflected or projected?
00:30:23 Juan Maldacena: Yeah. The real atoms would be on the boundary. The real elementary particles, another thing.
00:30:31 Then we’ve got some effective description … approximate description in terms of a space time in the interior.
00:30:38 In this picture, space time is … This is just an approximation.
00:30:41 It’s an approximation to the dynamics of lots of particles.
00:30:47 In the same way that properties of microscopic objects come from similar approximations, like the scarcity of water
00:30:55 or just the behavior of water waves and so on.
00:30:58 It comes from the collective motion of many of the concentrated molecules.
00:31:07 Interviewer: The thing you’re explaining to me how it works this hologram again? As simple as possible.
00:31:12 Juan Maldacena: This idea is the idea that you can describe gravitational physics,
00:31:19 or dynamics of space time at the quantum level. Which is something we don’t understand too well how to do it.
00:31:24 In terms of theory of particles. That lives on the boundary of that space time.
00:31:29 The theory of particles is very similar to the theory of particles we use for particle physics.
00:31:34 Or, some similar to the theory we use in the quantum mechanics. That’s a disconnection.
00:31:45 It connects for example black holes, to come on systems of particles that find the temperature.
00:31:56 If you assume … It’s a conjecture that these two things are related. It’s a conjecture that people work a lot on
00:32:05 and they found lots of ideas that this correct at least in very specific cases.
00:32:11 It’s a conjecture a conjecture between two let’s say mathematical theories.
00:32:16 One is the mathematics of strength theory in the space times, or quantum mechanical dynamical space times.
00:32:23 That’s described through strength theory, and ordinary theories of particle physics.
00:32:29 Many cases we can approximately describe each of the two sides, and then check mathematically that they’re correct.
00:32:35 The idea is to understand this further.
00:32:42 To understand better how space … What this implies for space time,
00:32:47 and how to build better theories of space time. In particular how to solve some of the problems we have with black
00:32:54 holes.
00:32:54 Black holes are understood reasonably well with the theory of Einstein’s … With Einstein’s theory of relativity.
00:33:09 Black holes have also give rise to some quantum mechanical effects.
00:33:11 More precisely once you take into account quantum mechanics.
00:33:15 Black holes can start to emit some kind of radiation Hawking discovered.
00:33:19 He discovered this theoretically, and it’s called Hawking radiation.
00:33:25 This implies that black holes are they form, and then they start emitting this radiation.
00:33:32 They emit a kind of soft glow.
00:33:36 Just to highlight how surprising this radiation is,
00:33:41 black holes were called black because they don’t emit any light. Anything that goes in has to fall in
00:33:48 and nothing can be emitted.
00:33:50 Interviewer: Can get out?
00:33:51 Juan Maldacena: Cannot get out. This radiation is something that is somehow getting out.
00:33:56 You can even have the [inaudible 00:33:58] situation of having a white black hole.
00:34:00 You have a black hole which is very tiny.
00:34:04 The size of the wave length of light, or the size of a bacteria roughly speaking.
00:34:09 That black hole will look white to our eyes. These black holes don’t form naturally in nature.
00:34:15 Black holes that form naturally in nature, are very big and have a very low temperature.
00:34:20 If you could form such a tiny black hole, theories predict that it should look white.
00:34:25 Here you see that there’ll be little conflict between Einstein’s theory of relativity,
00:34:29 in the beginning of a conflict you see it. One says it should be black, and the other one says it should be white.
00:34:36 Interviewer: White hole.
00:34:37 Juan Maldacena: Yeah. This is different from what people call a white hole, but this is a white black hole.
00:34:43 Here you see the beginning of some slight conflict between the two, and if you go deeper in,.
00:34:54 there are some laws of thermodynamics that should apply to any option that emits thermal .. This radiation is thermal.
00:35:03 It gets emitted at a certain temperature. That’s why you needed to make it very small, to make it look white.
00:35:11 Because the temperature becomes higher. The smaller the black hole is.
00:35:15 Small black hole is hotter than a bigger black hole.
00:35:18 I should make the black hole smaller,
00:35:23 it gets hotter. If you apply it with the laws of thermodynamics as we usually understand them,
00:35:31 they seem to hold for such black holes.
00:35:35 They are … They seem to be in some conflict with another fact that we know from general relativity.
00:35:40 Which is that if you solve the Einstein’s equations in black hole, there is a surface that we call the horizon.
00:35:46 Which is a surface basically right on the outside, and the inside. It’s an imaginary surface.
00:35:51 It’s not a real surface. It’s kind of point of no return.
00:35:58 If you cross the horizon, in the interior, you cannot send anything to the outside. You cannot even escape.
00:36:06 You’ll be doomed to fall in the singularity. You don’t feel anything when you cross the horizon.
00:36:12 It’s a perfectly reasonable surface. That’s what Einstein’s theory predicts.
00:36:23 This fact seems to somehow be in some conflict with this thermal properties of black holes,
00:36:29 and how to fully resolve this conflict. Is one of the things I and some other people are working on.
00:36:40 Interviewer: Is it something that you can call your life work?
00:36:44 Juan Maldacena: I would say that I’ve been mostly investigating this relationship between the interior
00:36:53 and the boundary. Also, trying to understand these problems with black holes. These problems with black holes.
00:37:01 The aspects of black holes.
00:37:03 Interviewer: Is this like your life researching this? Or is this just a job?
00:37:16 Juan Maldacena: It is a passion and I would like to really find the problem, and find a solution to the problem.
00:37:30 I hope it gets solved soon.
00:37:32 Interviewer: Are you close?
00:37:34 Juan Maldacena: Yeah. We seem to be close. Hopefully yes.
00:37:38 Interviewer: What I try to imagine, is because it’s also theoretical. You must have a big imagination.
00:37:52 When you think about it, what do you see?
00:37:55 Is it … And I don’t want you to explain the theory, but how do you represent this in your head? In your brain?
00:38:08 In colors, or in shapes, or in?
00:38:11 Juan Maldacena: Yeah.
00:38:12 Probably in terms of …By the way, we imagine formulas and their properties,
00:38:17 and we make a little mental image for these formulas.
00:38:21 We … For example, already for Einstein theory of relativity you have to imagine space time as some kind of membrane.
00:38:28 Interviewer: How do you imagine that?
00:38:31 Juan Maldacena: I imagine it same for classical space time for example, as a membrane
00:38:35 and the quantum one a membrane that is fluctuating. Those are the kind of mental images that we …
00:38:41 Interviewer: Sorry, a membrane?
00:38:42 Juan Maldacena: Well, space time is like a membrane that has certain shape. Has some dynamics of the shape can change.
00:38:51 If you get very close, this membrane has some oscillations and some structure.
00:38:58 That’s what we have at short distances. That’s a picture of the smallest standard for how to think about this.
00:39:09 One of the interesting things that we’ve been trying to understand and many people have begun to notice is that,
00:39:20 there is some connection between a certain property of quantum mechanics called entanglement.
00:39:26 Entanglement is a funny kind of correlation you can have in quantum mechanical systems. Which in some sense stronger
00:39:36 than classical correlations.
00:39:40 Before we discuss the fact that in some quantum mechanical systems you cannot predict the answer to certain experiments.
00:39:45 You might sometimes find 50% chance of one, or 50% chance of the other.
00:39:54 You’re going to have systems where you have two particles, and they’re separated.
00:40:00 You’re going to experiment here and you have 50% chance of each outcome.
00:40:03 You can do another experiment here and it’s again 50% chance of any outcome.
00:40:09 It might turn out that the outcomes of the two experiments are correlated. Let’s say the experiment is like flipping
00:40:18 a coin, it comes out heads here and it also comes out heads here.
00:40:21 If it comes tails here, it also will come out tails here. They’re perfectly correlated.
00:40:26 That’s an example of a classical correlation.
00:40:28 Entanglement is the fact that you can also measure another property at the same time.
00:40:35 If this coin which is not heads or tails but it’s the color, this is another analogy.
00:40:39 If the property is quantum mechanical that cannot be measure at the same time as the original property.
00:40:47 That’s one of the features also. Quantum mechanics.
00:40:50 That sometimes you can have two properties which you cannot measure at the same time. You can ask this coin whether
00:41:01 it’s heads or tails.
00:41:02 Or whether it says it’s black or white but you cannot ask where it’s black, and where it’s heads or tails.
00:41:08 It’s not a perfect analogy, or a classical variables are not of this kind. They’re mutually incompatible.
00:41:16 You can do that with this quantum let’s say properties, and again you can have two particles so that,
00:41:24 if you now measure, not only whether it’s heads or tails, but also black or white,
00:41:29 you have the same perfect correlation with the other.
00:41:34 That some kind of correlation that is not possible in classical physics, but it’s possible in quantum physics..
00:41:40 We think that [crosstalk 00:41:43]
00:41:41 Interviewer: Even though there’s a big distance?
00:41:42 Juan Maldacena: Yeah. Even though there is a big distance.
00:41:45 Again, with classical correlations, we can have these correlations because the two … You prepare the two kinds first,
00:41:51 and then you take them apart. Then you look at it. In classical physics, there’s no problem with this correlation.
00:41:58 What is interesting is that you can have correlation between variables that are mutually incompatible locally.
00:42:04 By compatible I mean that you either measure one or the other, but nevertheless you have a correlation.
00:42:10 Sometimes [inaudible 00:42:17] surprising property quantum mechanics, when it was noticed,
00:42:19 it was noticed in that paper by Einstein [inaudible 00:42:22] in the 1930s. Then while this was property,
00:42:29 and now it’s quite central notion for quantum information theory and people are using it in more practical ways.
00:42:39 To build … I mean, it would be essential for building quantum mechanical computer systems.
00:42:45 It also seems to be connected with the connections in space time.
00:42:50 Things that are closer to getting space time are more entangled with each other.
00:42:57 In some sense when you have the quantum field theory vacuum. The vacuum in the theory of particle physics.
00:43:06 If you want to split it in two parts,
00:43:08 the fundamental degrees of freedom are quantum variables that describe it. Are quite entangled with each other.
00:43:19 We think that in some circumstances if you take two separate systems, and you entangle them very strongly,
00:43:26 so you could also generate some kind of quantum connect. You can generate geometric connection between them.
00:43:32 In some cases. In some sense, through the entanglement is connected to the connectivity of space time. You can, yeah.
00:43:47 Interviewer: I want to try to get back to the beginning again.
00:43:58 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.
00:44:13 I would like to ask you to give definitions of the ingredients. Definitions for normal people.
00:44:31 What is time, what is space and what is relativity?
00:44:35 Juan Maldacena: Okay, good. Let’s start with time. Time is what the clock measures.
00:44:44 Now, this sounds like a circular definition,
00:44:48 but of course what’s not obvious is that different blocks made in different ways measure the same time.
00:44:54 It turns out if you have different kinds of clocks, and you make them,
00:45:01 they will all measure the same … They’ll measure the same … They’ll give the same answer.
00:45:05 That you can synchronize clocks and they stay synchronize and so on.
00:45:10 It looks like there is something that is being measured by these clocks.
00:45:14 This something is the abstraction we call time.
00:45:17 We have the time we feel psychologically which is not a perfect clock,
00:45:21 but certainly agrees with more precise physical clocks. All clocks that measure time are made of physical particles,
00:45:30 and that’s how we measure time. That’s how we define it.
00:45:35 It’s an abstraction but this is the thing that all these clocks are measuring. What is space?
00:45:44 Space is somehow the distance between the … Let’s say the nothingness that exists between two objects.
00:45:55 Now, it’s what’s missing when you go into a crowded bus. That’s space. What’s this relativity?
00:46:08 Let’s first discuss special relativity.
00:46:10 Before when I was discussing time, I said that all clocks measure the same time.
00:46:15 That is only true for clocks that are stationary. If you have a clock here.
00:46:19 Another clock here, and both stay at rest relative to each other,
00:46:23 then they will measure the same time. If you have a clock here. Another clock moving, they will measure different time.
00:46:32 Relativity, special relative that’s how different is this other time the clock measures.
00:46:37 It’s a simple law for how to find out how to.
00:46:46 The theory of relativity is the theory that postulates the speed of light. It’s constant. It’s absolute.
00:46:54 If you could also have call it absolute something.
00:47:00 What’s relative is time, but that doesn’t mean everything is relative.
00:47:05 Interviewer: This envisioning what is light?
00:47:07 Juan Maldacena: Well, you could replace light by other things like gravity where it’s also propagated the speed.
00:47:15 More precisely, I should have said it’s the maximum speed of propagation of signals.
00:47:20 The idea is that there is a maximum speed for the propagation of signals.
00:47:27 So happens that light propagates at this speed.
00:47:29 If you had a massive particle, it would generally propagate at a lower speed.
00:47:35 If you try to push a massive particle to move it faster and faster and faster,
00:47:39 you could not make it move faster than this maximum speed. Which is also coincides with the speed of light.
00:47:45 Interviewer: That’s why it’s absolute?
00:47:47 Juan Maldacena: Yeah. Different observers would measure exactly the same speed.
00:47:52 Interviewer: Why do you want to have an explanation for how life started?
00:48:05 Juan Maldacena: Well, it’s not an explanation about how life started, but how the beginning of space time started.
00:48:11 How time originated and what happened at the beginning of the big bang.
00:48:18 We’re trying to understand it because that’s something we don’t know.
00:48:22 Science is always about pushing the boundaries.
00:48:26 We don’t … It’s not just the fact that we don’t know how it happened,
00:48:31 but even we don’t have a theory that is [self 00:48:36] consistent that could describe it.
00:48:36 We are even trying to find theories that could in principle describe the big bang,.
00:48:43 then we’ll have the problem of finding .. That’s the way the big bang actually happened. Yeah.
00:48:50 That’s why we think the problem may be solved by thinking about it, and finding the theory
00:48:55 and then perhaps making some new predictions that we could test experimentally.
00:48:59 Interviewer: Yeah, but all the time the same question arises again. What happened before the big bang?
00:49:07 Questions like that. How do you deal with this almost impossible …
00:49:11 Juan Maldacena: The idea is to make a theory, and maybe you can make a theory which has a time before.
00:49:21 Maybe you can make a theory where time actually starts in the big bang,
00:49:26 and does not have any meaning before … Sort of the question doesn’t have a meaning.
00:49:32 We don’t know what the right answer is. That’s what we’re trying to find out with this concept.
00:49:38 People imagine now maybe there was a time before, and somehow we went through a big bang. These are just words.
00:49:45 They are not self-consistent equations where you can have such a thing.
00:49:52 If you try to make a theory where the universe was contracting, and then expanding again for example,
00:49:58 they violate some principles that we think should be true in the theory of quantum gravity.
00:50:04 Interviewer: When did yourself ask this question for the first time?
00:50:09 Juan Maldacena: I guess as I started learning more about physics.
00:50:16 I started recognizing where the boundaries of physics were, and there are boundaries of physics in many directions.
00:50:24 In the direction of very complex systems, in very different directions.
00:50:28 This is one of the directions in which we see a boundary. I wanted to go to the frontier in this direction.
00:50:38 I guess the physics they’re trying to roll was expanding. Push the frontier further and further away.
00:50:44 Interviewer: Right now you are as a frontier?
00:50:47 Juan Maldacena: Yeah. This is certainly one of the frontiers.
00:50:50 Interviewer: What do you see when you look ahead?
00:50:53 Juan Maldacena: I see confusion. I see lack of understanding.
00:50:59 The idea is to find patterns in this confusion, and to move forward.
00:51:07 To understand things that we currently don’t understand [crosstalk 00:51:11] bit by bit.
00:51:12 Usually you advance one step at a time, and get a little further, and a little further, and.
00:51:19 Interviewer: Do you feel something like a competitor?
00:51:24 Or, something like a challenge or something which challenges some things … Some works.
00:51:34 Somebody who challenges you to try to find it. Something like that.
00:51:41 Juan Maldacena: Yeah. Certainly we were trying to find this answer, and we really want to get the answer.
00:51:48 Sometimes you feel, sometimes its close.
00:51:51 Then you realize maybe I made a mistake, and you … It’s all happening also personally,
00:51:58 but within a community of researchers who’s trying to find this.
00:52:02 You criticize the ideas of others, and others criticize your ideas and this way you make progress.
00:52:08 Because it’s a difficult problem
00:52:10 and you need the … You need insights from many people that know different aspects of theoretical phases of physics in
00:52:20 general and can inform this.
00:52:22 Interviewer: Is it possible to think of something like an entity who is on the other side of this frontier?.
00:52:29 Or, maybe not an entity but [crosstalk 00:52:33]
00:52:32 Juan Maldacena: Well, there might be another intelligence in our universe who has already figured out this.
00:52:36 He has figured this out, and has understood these problems. At least it’s not known to us.
00:52:43 Interviewer: When you are on the frontier like the west was [won 00:52:58] here in the United States.
00:52:59 You don’t know what’s out there, but you go there and you find things.
00:53:03 It’s because you didn’t know that there were Indians, and there was another Coast and another ocean.
00:53:10 There is some awareness on the other side of the frontier. Only we don’t know.
00:53:17 What kind of awareness is on the other side of your frontier?
00:53:20 Juan Maldacena: Well, by awareness you mean the Indians.
00:53:23 Well, you’re putting too many anthropomorphical things that were not present in this discussion.
00:53:31 We only known intelligence in the universe, only known being that is trying to understand the universe.
00:53:38 We are just expanding.
00:53:41 When I say expanding the frontier,
00:53:43 it’s just understanding the questions that they’re understanding laws of physics better.
00:53:47 These entities are very simple things.
00:53:50 One of the features of physics is that I think is amazingly interesting,
00:53:55 is how simple the fundamental physics laws are.
00:53:58 Of course you might say, if it takes a couple of years to understand it, and you need to study or maybe more,
00:54:05 maybe you need to understand, study physics for five years to understand.
00:54:08 Then,
00:54:08 why are you saying they are simple? They are simple in the sense that the actual laws that govern the emotional zone,
00:54:13 are really simple. You don’t have to come up with rules and lots of books and so on.
00:54:20 It’s been very different than the laws that you find in the senators,
00:54:27 and people produce where there are exceptions here and there.
00:54:33 Here there’s a very simple statement, and this is followed by everything we know.
00:54:40 Interviewer: It’s true?
00:54:40 Juan Maldacena: It’s true to the extent that we’ve been able to experimentally verify,
00:54:47 and the statements have simple learning language which is unfamiliar. A language which takes a long time to learn.
00:54:53 That’s what takes a long time. It’s just to learn this language in which the formula is the laws..
00:54:58 Once the laws are formulated, they’re in a very simple way. Once you [crosstalk 00:55:04]
00:55:03 Interviewer: Which one do you like the most?
00:55:04 Juan Maldacena: Well, I think the general relativity is the most beautiful theory.
00:55:09 Because it translates physics into geometry. This is a very nice theory.
00:55:16 We don’t know how to make such a beautiful theory out of quantum mechanics. Maybe it will exist at some point.
00:55:27 Interviewer: For you as a child for example, what led to this position you have right now on this frontier?
00:55:38 Where did it start?
00:55:40 Juan Maldacena: Well, as a child I was watching my father for example fixing the washing machine,
00:55:47 and trying to learn how to do it myself. Again, understanding how everyday objects work.
00:55:56 Like the washing machine, the car, the radio and so on.
00:56:01 You learn a little bit about technology and how technology exploits the laws of physics.
00:56:08 That got me interested in understanding the laws of physics which underlie technology. Seeing how far they understood..
00:56:17 What things are known, what things are not known, and [crosstalk 00:56:22]
00:56:21 Interviewer: How did you do that as a child?
00:56:22 Juan Maldacena: Well, as a child I was mostly interested in technology and how things worked.
00:56:27 Then, when I was in high school I got a little more interested in the laws of physics and chemistry.
00:56:35 and [crosstalk 00:56:37]
00:56:36 Interviewer: What did you do to explore as a child?
00:56:40 Juan Maldacena: Mainly taking things apart and seeing how they worked. That’s basically the process.
00:56:48 Interviewer: Yeah? Putting them together again?
00:56:50 Juan Maldacena: Yeah. I was taking them apart, putting them together.
00:56:52 Just learning how to fix the household appliances.
00:56:56 Interviewer: That’s practical. I mean, if you try to find out how it’s made and why it works. Of course, I guess?
00:57:09 Juan Maldacena: Right. I was always curious in understanding how things work. I mean, how does a TV work?
00:57:15 How does a radio work? What’s the actual principle it uses.
00:57:21 Interviewer: Do you know now?
00:57:22 Juan Maldacena: Yeah. I think I know the basics. I wouldn’t know all the details..
00:57:27 I guess the technology which I again [crosstalk 00:57:30]
00:57:30 Interviewer: You know, you can … You know how a television works because you understand the physics inside?
00:57:40 Or is it like comparing it to the laws of physics?
00:57:52 Juan Maldacena: Well, the TV or any simple … Any machine,
00:57:59 even simpler perhaps is better to think out the simpler machine first.
00:58:02 Has different parts, and they work together to … Each part is there for a reason,
00:58:08 and they work together to make the machine work.
00:58:19 Most of our everyday machines are … Television is made out of electronic circuits.
00:58:22 They’ll move currents around, and they do … They show the light on the screen and so on..
00:58:29 That makes a television work, and you have to understand how this [crosstalk 00:58:35]
00:58:34 Interviewer: Does a child who was your age did that?
00:58:38 Juan Maldacena: Well, maybe I was perhaps from eight to 12 would be doing this thing of taking machines apart
00:58:45 and putting them together
00:58:47 Interviewer: What did your parents say about that? Don’t do it again?
00:58:51 Juan Maldacena: No. My dad liked to do this himself, so.
00:58:57 Interviewer: Taking things apart you learned from your father?
00:58:59 Juan Maldacena: Yeah. That’s right..
00:59:00 Interviewer: What [crosstalk 00:59:02]
00:59:01 Juan Maldacena: My mother liked to give things fixed, so. My dad always liked to fix things.
00:59:10 He was very practical, and he liked the challenge of fixing.
00:59:14 Sometimes,
00:59:14 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..
00:59:19 Then you manage to understand how it works [crosstalk 00:59:23]
00:59:22 Interviewer: When you are on the road, and your car has a problem you can fix it?
00:59:26 Juan Maldacena: Well, I was able to do that in the past. Now, cars got more complicated. I don’t know.
00:59:33 This car hasn’t broken down recently, so I can’t tell for sure.
00:59:37 Interviewer: It all started at a young age, and it’s almost you inherited from your father.
00:59:50 Now you are here at Princeton Advanced Studies Institute.
00:59:52 In a position where you are allowed to think as much as you can?
01:00:08 Juan Maldacena: Right. I’m encouraged to think and do research all the time.
01:00:14 Interviewer: Is it too simple to say that your job is thinking?
01:00:21 Juan Maldacena: Yeah. It’s thinking. It’s discussing.
01:00:23 Its learning what other people are thinking and reading what other people write. Trying to make a progress.
01:00:30 Interviewer: Are you thinking all the time?
01:00:31 Juan Maldacena: Well, I mean no. I’m reading what other people write.
01:00:38 I’m listening to other people’s ideas and presentations, and discussing with my colleagues..
01:00:45 We are writing formulas, and [crosstalk 01:00:51]
01:00:48 Interviewer: Can you decide, now I start thinking? Or does it happen? Or, how does it work? This thinking process.
01:00:56 Juan Maldacena: I guess the thinking normally you try to … This problem sounds very vague and grand.
01:01:04 We try to think on very concrete problems where we can make progress.
01:01:08 There are the questions that are extremely interesting, but almost impossible to solve.
01:01:12 There are questions which are perhaps too easy to solve. We try to be in between.
01:01:16 Try to find the most difficult or interesting questions that you can actually say something useful about.
01:01:20 Lots of thinking is trying to focus on such questions.
01:01:24 Try to imagine very simple toy models, or simple models where we can say something new.
01:01:31 Interviewer: Maybe a few easy answers together might solve a more difficult answer?
01:01:37 Juan Maldacena: Yeah. This thing that I was saying before. You do a step at a time.
01:01:41 We have to figure out where we do the next step.
01:01:43 Next step is in something we more or less know, but moves us in the right direction.
01:01:48 From which we can get a better view of what the next step would be.
01:01:52 Interviewer: When do you do your best thinking?.
01:01:55 Juan Maldacena: Well, I think during the day and [crosstalk 01:02:03].
01:02:00 Interviewer: Is all that you are the way [inaudible 01:02:04] For example, when you’re outside, or.
01:02:06 when you’re in the shower [crosstalk 01:02:10]
01:02:07 Juan Maldacena: It’s mostly I would say in my office, talking to other people.
01:02:14 Normally when you talk to other people, you get new ideas.
01:02:20 and usually many times ideas come together in this [crosstalk 01:02:25]
01:02:25 Interviewer: Those colleagues are gone and then you have to write down the idea?.
01:02:29 Or, do you have to [crosstalk 01:02:32]
01:02:30 Juan Maldacena: We write them together, and we certainly write articles with other people. This is important.
01:02:38 Most of my … Are with other people. We are collaborators.
01:02:42 Interviewer: Yes. Once someone said it’s hard to sit. It’s hard to sit and not to think.
01:02:57 It’s so hard to shut down your thinking. How do you think about that?
01:03:03 Juan Maldacena: Well,
01:03:04 it’s something … I guess you have to be a little obsessive sometimes to work on these problems.
01:03:11 Because you want to think of these problems and you have to know other things.
01:03:14 It’s easy to get distracted and think about something else. When you’re not making progress.
01:03:18 If you’re trying to solve a problem and you’re not making progress, it’s easy to get distracted.
01:03:25 Sometimes you need to keep trying to find solutions to that problem you initially set out to do.
01:03:31 Being slightly obsessive about it. Then you can make some progress.
01:03:35 Interviewer: You are obsessive?
01:03:36 Juan Maldacena: Slightly, yeah.
01:03:41 Interviewer: When there’s something distractive, what is your distraction?
01:03:46 Juan Maldacena: Well, it could be some other interesting idea in some other slightly different field.
01:03:54 Sometimes it’s good to be distracted. Maybe the problem you’re trying to solve was bad, and so it’s a balance.
01:04:06 Interviewer: Or, you can say this is what you’re good at, and you make progress and solutions or answers.
01:04:16 Is there also an area in which you are able to find the answers? The opposite of your talent?
01:04:31 Juan Maldacena: Yeah. I’m not sure. Fashion..
01:04:43 Interviewer: Yeah. You cannot describe that into one [crosstalk 01:04:50]
01:04:49 Juan Maldacena: That’s right.
01:04:51 Interviewer: I mean in your character.
01:04:56 If you are obsessive in finding answers in this theoretical field, but it’s also
01:05:04 when you find it you can write it down in one line. Then it’s true..
01:05:09 Unlike political laws with all the kinds of … What is the area in which [crosstalk 01:05:17]
01:05:18 Juan Maldacena: I think the process is not that you write down a formula and then it is true.
01:05:21 Normally in physics, the process is that for some physical theory to be true, you have to be compared to experiment..
01:05:28 Interviewer: I’m sorry [crosstalk 01:05:30]
01:05:30 Juan Maldacena: It’s checked against experiment. Then we become more sure that it’s probably true.
01:05:36 Can always be some other experiment that contradicts it.
01:05:40 As many experiments that agree with it, you feel more and more confident..
01:05:43 Interviewer: Yeah. I’m sorry to say that, then I say that it’s true [crosstalk 01:05:47] They agree on it.
01:05:48 Juan Maldacena: Yeah.
01:05:50 Many times … A lot of our work sometimes is to … There are some mathematical relations like … The reason for this
01:06:00 is that some of our work is mathematics, is because the laws of physics are written in this mathematical language.
01:06:09 Sometimes even laws which are in principle simple like this equations of Einstein, which are simple to write down,
01:06:16 but they’re very difficult to solve.
01:06:18 You need your computers, and with time engineers, ideas to solve the questions,
01:06:27 and …Once you find for example some solution of the equation, you can check that it is the solution.
01:06:31 Then it becomes a true solution. That’s an example way. That’s where you could say, well its mathematics.
01:06:38 It’s within the … If you assume the questions are the correct description of physics,
01:06:43 this is a solution of the equations.
01:06:45 Interviewer: Correct me if I’m wrong,
01:06:48 but mathematics is like an instrument for you to understand what you need to understand. What you want to understand?
01:06:56 Juan Maldacena: Exactly. Before we were talking about the language in which these laws are written.
01:07:00 This is a language that is fairly mathematical..
01:07:04 You need to know enough mathematics to be able to understand the [crosstalk 01:07:08]
01:07:07 Interviewer: I can imagine that this mathematics, you are talented for using it.
01:07:15 It’s a way to look around you and follow your obsession.
01:07:22 There are also very much a lot of areas in which mathematics just doesn’t work.
01:07:30 Then you … Which areas are that, that you cannot use math?
01:07:40 Juan Maldacena: There are many areas I really like where we don’t necessarily use math.
01:07:45 If I want to learn the piano, math is not very useful.
01:07:50 Or if I want to play soccer, I learned to play soccer but math is not very useful.
01:07:56 You just have to practice playing soccer.
01:07:58 If I want to cook [data 01:08::01] in my lunch or cook a nice meal, math is also not very useful..
01:08:06 There are lots of areas but [crosstalk 01:08:08]
01:08:08 Interviewer: What are the things which you are not good at?
01:08:11 Juan Maldacena: Playing soccer, and sports.
01:08:17 Interviewer: Do you like it?
01:08:20 Juan Maldacena: I do it sometimes.
01:08:22 Interviewer: Is that an aspect of mathematics as well? That you can like it?
01:08:31 Juan Maldacena: If I like mathematics because of some aspect?
01:08:36 I like some aspects of mathematics because first it’s a nice tool to describe physics and,
01:08:44 I certainly like it’s interesting.
01:08:47 While mathematics is also a subject on its own and it’s huge, I know a little bit of mathematics,
01:08:53 and I write down the mathematics I think would be useful for this problem.
01:08:59 Sometimes people need to learn, invent some new mathematics to solve these problems.
01:09:05 Interviewer: Yeah. For example, I’m much more comfortable when I talk to people, trying to understand people.
01:09:17 I’m not comfortable when I talk with other people about mathematics.
01:09:21 Because it’s not my thing, or my talent, or … I choose the things in which I’m comfortable,
01:09:33 and that’s what I’m doing right now.
01:09:34 I’m [firmly 01:09:36] interviewing people, trying to have that person at work.
01:09:39 Juan Maldacena: Right. That’s true.
01:09:44 We all know what our strengths are, and we try to do an activity where we can really use our talents.
01:09:51 Yeah, certainly I would be a very bad interviewer. To know what the other person is thinking or trying to guess it.
01:09:59 Yeah, we all do these various talents.
01:10:04 Our natural … Well, we develop some talents and I guess through part of our lives, we continue developing them
01:10:11 and we get better at those areas.
01:10:13 Interviewer: Anna, told me about … Because I don’t want to forget that one.
01:10:29 Two stories she told about the mountain and a valley, and about Romeo and Juliet.
01:10:37 Juan Maldacena: Okay.
01:10:41 Interviewer: Do you think it’s interesting to tell that? For understanding your theory?
01:10:52 Juan Maldacena: Yeah. I’m trying to remember what the story about the mountain and the valley was.
01:10:56 Interviewer: That if you live in a mountain … a valley,.
01:11:01 and you have no reason to go up on the mountain because you cannot go [crosstalk 01:11:07]
01:11:06 Juan Maldacena: Oh, yeah. This was … I think the original question was, was this useful for anything?
01:11:12 Or, what are the technological applications of this research, or this area of research?
01:11:22 This area of research doesn’t have a direct technological application that we know of.
01:11:29 We do it because we want to know wand we want to understand.
01:11:34 An analogy is that to think that we have, let’s say, a town that lives in a valley.
01:11:39 The valley’s fertile and they grow corn, and their grow food in the valley.
01:11:44 There’s a nearby mountain and there’s mountains surrounding the valley.
01:11:49 Someone might decide to go up the mountain just to see what’s there. The expedition of going up the mountain might be
01:11:56 totally useless for growing better corn, or you’ll not plant anything nice in the mountains.
01:12:01 Certainly going up the mountain might give you better view of the valley.
01:12:07 Might help you understand where this valley is located. It might allow you to see another valley.
01:12:13 This is not guaranteed. Maybe there are all mountains, and there are no other valleys.
01:12:16 It’s certainly part of the curiosity of seeing where we are,
01:12:21 and to extend the frontier to really understand better where we are sitting in the universe.
01:12:32 This is one direction in which we can go and certainly that’s where we … I mean,
01:12:36 it’s like a mountain that it’s there. We’re trying to go to the summit
01:12:39 and try to understand the summit is understanding the big bang singularity..
01:12:43 Is understanding the beginning of the big bang. I will try to climb this mountain the whole way. [crosstalk 01:12:50]
01:12:49 Interviewer: Are you on the mountain?
01:12:52 Juan Maldacena: Well, we don’t know. Because we don’t have a view of the mountain from outside.
01:12:55 We only know that we are climbing. I think we are confident we are climbing. We are not going down.
01:13:00 There must be a summit.
01:13:02 Interviewer: It’s a nice one.
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