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Frank Wilczek: Physics of Quarks, Dark Matter, Complexity, Life & Aliens | Lex Fridman Podcast #187


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The following is a conversation with Frank Wilczek, a theoretical physicist at MIT,
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who won the Nobel Prize for the co discovery of asymptotic freedom in the theory of strong
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interaction. Quick mention of our sponsors, The Information, Netsuite, ExpressVPN, Blinkist,
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and AIDSSleep. Check them out in the description to support this podcast.
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As a side note, let me say a word about asymptotic freedom. Protons and neutrons make up the nucleus
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of an atom. Strong interaction is responsible for the strong nuclear force that binds them,
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but strong interaction also holds together the quarks that make up the protons and neutrons.
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Frank Wilczek, David Gross, and David Pulitzer came up with a theory postulating that when
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quarks come really close to one another, the attraction abates and they behave like free
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particles. This is called asymptotic freedom. This happens at very, very high energies,
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which is also where all the fun is. This is the Lex Friedman podcast, and here is my conversation
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with Frank Wilczek. What is the most beautiful idea in physics?
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The most beautiful idea in physics is that we can get a compact description of the world that's
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very precise and very full at the level of the operating system of the world. That's
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an extraordinary gift, and we get worried when we have fine discrepancies between
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our description of the world and what's actually observed at the level even of a part in a billion.
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You actually have this quote from Einstein that the most incomprehensible thing,
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but the universe is that it is comprehensible, something like that.
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Yes. That's the most beautiful surprise that really was, to me, the most profound result of
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the scientific revolution of the 17th century with the shining example of Newtonian physics
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that you could aspire to completeness, precision, and a concise description of the world of the
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operating system, and it's gotten better and better over the years, and that's the continuing
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miracle. Now, there are a lot of beautiful submiracles, too. The form of the equations is
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governed by high degrees of symmetry, and they have a very surprising kind of mind expanding
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structure, especially in quantum mechanics. But if I have to say that the single most
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beautiful revelation is that, in fact, the world is comprehensible.
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Would you say that's a fact or a hope?
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It's a fact. You can point to things like the rise of
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gross national products per capita around the world as a result of the scientific revolution.
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You can see it all around you in recent developments, so exponential production of wealth,
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control of nature at a very profound level where we do things like sense tiny, tiny, tiny,
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tiny vibrations to tell that there are black holes colliding far away, or we test laws as I
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alluded to, as a part in a billion, and do things in what appear on the surface to be
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entirely different conceptual universes. I mean, on the one hand, pencil and paper or
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nowadays computers that calculate abstractions, and on the other hand, magnets and accelerators
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and detectors that look at the behavior of fundamental particles, and these different
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universes have to agree or else we get very upset. And that's an amazing thing if you think about it.
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It's telling us that we do understand a lot about nature at a very profound level,
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and there are still things we don't understand, of course, but as we get better and better answers
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and better and better ability to address difficult questions, we can ask more and more ambitious
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questions. Well, I guess the hope part of that is because we are surrounded by mystery, so one
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way to say it, if you look at the growth of GDP, over time that we figured out quite a lot and
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we're able to improve the quality of life because of that, and we've figured out some
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fundamental things about this universe, but we still don't know how much mystery there is,
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and it's also possible that there's some things that are, in fact, incomprehensible to both our
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minds and the tools of science. The sad thing is we may not know it because, in fact, they are
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incomprehensible. And that's the open question, is how much of the universe is comprehensible?
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If we figured out everything was inside the black hole and everything that happened at the
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moment of the Big Bang, does that still give us the key to understanding the human mind
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and the emergence of all the beautiful complexity we see around us? That's not,
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like, when I see these objects, like, I don't know if you've seen them, like cellular automata,
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all these kinds of objects where from simple rules emerges complexity, it makes you wonder,
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maybe, it's not reducible to simple, beautiful equations, the whole thing, only parts of it.
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That's the tension I was getting at with the hope.
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Well, when we say the universe is comprehensible, we have to
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kind of draw careful distinctions about, or definitions about what we mean by that.
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Both the universe and the comprehensibles.
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Exactly. So in certain areas of understanding reality, we've made extraordinary progress,
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I would say, in understanding fundamental physical processes and getting very precise
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equations that really work and allow us to do profound sculpting of matter, to make computers
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and iPhones and everything else, and they really work, and they're extraordinary productions.
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That's all based on the laws of quantum mechanics, and they really work.
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And they give us tremendous control of nature. On the other hand, as we get better answers,
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we can also ask more ambitious questions, and there are certainly things that
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have been observed even in what would be usually called the realm of physics that
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aren't understood. For instance, there seems to be another source of mass in the universe,
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the so called dark matter, that we don't know what it is, and it's a very interesting question
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what it is. But also, as you were alluding to, it's one thing to know the basic equations.
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It's another thing to be able to solve them in important cases. So we run up against the limits
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of that in things like chemistry, where we'd like to be able to design molecules and predict their
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behavior from the equations. We think the equations could do that in principle, but in practice,
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it's very challenging to solve them in all but very simple cases. And then there's the other
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thing, which is that a lot of what we're interested in is historically conditioned. It's not a
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matter of the fundamental equations, but about what has evolved or come out of the early universe
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and formed into people and frogs and societies and things. And the laws of physics, the basic
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laws of physics only take you so far, and that kind of provides a foundation but doesn't really,
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the unique entirely different concepts to deal with those kind of systems. And one thing I can
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say about that is that the laws themselves point out their limitations, that they kind of,
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their laws for dynamical evolution. So they tell you what happens if you have a certain starting
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point, but they don't tell you what the starting point should be at least. And the other thing
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that emerges from the equations themselves is the phenomena of chaos and sensitivity to initial
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conditions, which tells us that there are intrinsic limitations on how well we can spell
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out the consequences of the laws if we try to apply them. The old apple pie, if you want to,
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what does it make an apple pie from scratch? You have to build the universe or something like that.
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You're much better off starting with apples than starting with quarks. Let's put it that way.
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In your book, A Beautiful Question, you ask, does the world body beautiful ideas? So the book is
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centered around this very interesting question. It's like Shakespeare. You can like dig in and
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read into all the different interpretations of this question. But at the high level,
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what to use the connection between beauty of the world and physics of the world?
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In a sense, we now have a lot of insight into what the laws are, the form they take that
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allow us to understand matter in great depth and control it as we've discussed.
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And it's an extraordinary thing how mathematically ideal those equations turn out to be.
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In the early days of Greek philosophy, Plato had this model of atoms built out of the five
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perfectly symmetrical botanic solids. So there was somehow the idea that mathematical symmetry
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should govern the world. And we've outplayed out Plato by far in modern physics because we have
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symmetries that are much more extensive, much more powerful, that turn out to be
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the ingredients out of which we construct our theory of the world. And it works.
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And so that's certainly beautiful. So the math, the idea of symmetry, which is
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a driving inspiration in much of human art, especially decorative art, like the Alhambra
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or wallpaper designs or things you see around you everywhere, also turns out to be the dominant theme
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in modern fundamental physics, symmetry and its manifestations. The laws turn out to be very,
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to have these tremendous amounts of symmetry. You can change the symbols and move them around
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in different ways and they still have the same consequences. So that's beautiful.
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And that these things, these different, these concepts that humans find appealing,
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also turn out to be the concepts that govern how the world actually works.
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I don't think that's an accident. I think humans were evolved to be able to interact with the world
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in ways that are advantageous and to learn from it. And so we are naturally evolved or designed
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to enjoy beauty and to symmetry and the world has it. And that's why we resonate with it.
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Well, it's interesting that the ideas of symmetry emerge at menu levels of the hierarchy
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of the universe. So you're talking about particles, but it also is at the level of chemistry and biology
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and the fact that our cognitive, sort of our perception system and whatever our cognition is
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also finds it appealing or somehow our sense of what is beautiful is grounded in this idea of
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symmetry or the breaking of symmetry. Symmetry is at the core of our conception of beauty,
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whether it's the breaking or the non breaking of the symmetry. It makes you wonder why, why?
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Like, so I come from Russia and the question of Dostoevsky, he's said that beauty will save
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the world. Maybe as a physicist you can tell me, what do you think he meant by that?
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I don't know if it saves the world, but it does turn out to be a tremendous source of insight into
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the world when we investigate kind of the most fundamental interactions, things that are hard
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to access because they occur at very short distances between very special kinds of particles
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whose properties are only revealed at high energies. We don't have much to go on from
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everyday life, but so we have when we guess what the, and the experiments are difficult to do,
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so you can't really follow a very wholly empirical procedure to sort of in the Baconian style,
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figure out the laws kind of step by step just by accumulating a lot of data.
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What we actually do is guess, and the guesses are kind of aesthetic really, what would be a nice
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description that's consistent with what we know, and then you try it out and see if it works,
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and by gosh it does in many profound cases. So there's that, but there's another source
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of symmetry, which I didn't talk so much about in a beautiful question, but does
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relate to your comments, and I think very much relates to the source of symmetry that we find in
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biology and in our heads, in our brain, which is that, well, it is discussed a bit in a beautiful
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question and also in fundamentals, is that when you have, symmetry is also a very important
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means of construction, so when you have, for instance, simple viruses that need to construct
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their coat, their protein coat, the coats often take the form of platonic solids,
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and the reason is that the deviruses are really dumb, and they only know how to do one thing,
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so they make a pentagon, then they make another pentagon, and they make another pentagon, and
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they all glue together in the same way, and that makes a very symmetrical object, so the rules of
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development, when you have simple rules and they work again and again, you get symmetrical patterns,
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that's kind of, in fact, it's a recipe also for generating fractals, like the kind of broccoli
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that has all this internal structure, and I wish I had a picture to show, but maybe people
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remember it from the supermarket, and you say, how did a vegetable get so intelligent to make
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such a beautiful object with all this fractal structure, and the secret is stupidity,
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you just do the same thing over and over again, and in our brains, also, we came out, we start
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from single cells, and they reproduce, and each one does roughly the same thing, the program
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evolves in time, of course, different modules get turned on and off, different regions of
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the genetic code get turned on and off, but basically, a lot of the same things are going
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on, and they're simple things, and so you produce the same patterns over and over again,
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and that's a recipe for producing symmetry, because you're getting the same thing in many,
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many places, and if you look at, for instance, the beautiful drawings of Ramon Icahal, the great
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neuroanatomist who drew the structure of different organs like the hippocampus,
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you see it's very regular and very intricate, and it's symmetry in that sense, it's many
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repeated units that you can take from one place to the other and see that they look more or less
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the same. But what you're describing, this kind of beauty that we're talking about now is a very
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small sample in terms of space time in a very big world, in a very short, brief moment in this
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long history. In your book, Fundamentals, 10 Keys to Reality, I'd really recommend people read it.
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You say that space and time are pretty big, or very big. How big are we talking about? Like,
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what can you draw? Can you tell a brief history of space and time?
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It's easy to tell a brief history, but the details get very involved, of course. But one thing I'd
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like to say is that if you take a broad enough view, the history of the universe is simpler than
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the history of Sweden, say, because your standards are lower. But just to make it
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quantitative, I'll just give a few highlights. And it's a little bit easier to talk about time.
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So let's start with that. The Big Bang occurred. We think the universe was much hotter and denser
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and more uniform about 13.8 billion years ago. And that's what we call the Big Bang.
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And it's been expanding and cooling. The matter in it has been expanding and cooling
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ever since. So in a real sense, the universe is 13.8 billion years old. That's a big number,
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kind of hard to think about. A nice way to think about it, though, is to map it onto one year.
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So let's say the universe just linearly mapped the time intervals from 13.8 billion years onto
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one year. So the Big Bang, then, is that on January 1st at 12am. And you wait for quite a long time
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before the dinosaurs emerge. The dinosaurs emerge on Christmas, it turns out.
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12 months, almost 12 months later. Getting close to the end.
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And the extinction event that let mammals and ultimately humans inherit the earth from
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the dinosaurs occurred on December 30th. And all of human history is a small part of the last day.
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And so, yes, so we're occupying only a human lifetime is a very, very infinitesimal part of this
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interval of these gigantic cosmic reaches of time. And in space, we can tell a very similar story.
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In fact, it's convenient to think that the size of the universe is the distance that light can
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travel in 13.8 billion years. So it's 13.8 billion light years. That's how far you can see out.
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That's how far signals can reach us from. And that is a big distance because compared to that,
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the universe, the earth is a fraction of a light second. So again, it's really, really big.
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And so we have, if we want to think about the universe as a whole in space and time,
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we really need a different kind of imagination. It's not something you can
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grasp in terms of psychological time in a useful way. You have to think, you know,
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you have to use exponential notation and abstract concepts to really get any hold on these vast
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times and spaces. On the other hand, let me hasten to add that that doesn't make us small
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or make the time that we have to us small. Because again, looking at those pictures of what
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our minds are and some of the components of our minds, these beautiful drawings of the cellular
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patterns inside the brain, you see that there are many, many, many processing units. And if you
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analyze how fast they operate, I try to estimate how many thoughts a person can have in a lifetime.
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That's kind of a fuzzy question, but I'm very proud that I was able to define it pretty precisely.
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And it turns out we can, we have time for billions of meaningful thoughts
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in a lifetime. So it's a lot. We shouldn't think of ourselves as terribly small,
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either in space or in time, because although we're small in those dimensions compared to
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the universe, we're large compared to meaningful units of processing information and being able
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to conceptualize and understand things. Yeah, but 99% of those thoughts are probably food, sex,
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or internet related. Well, that's only like 0.1 is Nobel Prize winning ideas.
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But that's true. But you know, there's more to life than winning Nobel prizes.
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How did you do that calculate? Can you maybe break that apart a little bit just kind of
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for fun, sort of an intuition of how we calculate the number of thoughts?
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The number of thoughts, right. It's necessarily imprecise because a lot of
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things are going on in a different way than what is a thought. But there are several things that
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point to more or less the same rate of being able to have meaningful thoughts.
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For instance, the one that I think is maybe the most penetrating is how fast we can process
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visual images. How do we do that? If you've ever watched old movies,
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you can see that when, well, any movie, in fact, that in a motion picture is really not a motion
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picture. It's a series of snapshots that are playing one after the other. And it's because
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our brains also work that way. We take snapshots of the world, integrate over a certain time,
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and then go on to the next one. And then by post processing, create the illusion of continuity
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and flow, we can deal with that. And if the flicker rate is too slow, then you start to see
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that it's a series of snapshots. And you can ask, what is the crossover? When does it change from
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being something that is matched to our processing speed versus too fast? And it turns out about
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40 per second. And then if you take 40 per second as how fast we can process visual images, you get
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to several billions of thoughts. Similarly, if you ask, what are some of the fastest things
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that people can do? Well, they can play video games. They can play the piano very fast if
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they're skilled at it. And again, you get to similar units or how fast can people talk?
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You get to similar, you know, within a couple of orders of magnitude, you get more or less to
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the same idea. So that's how you can say that there's billions of meaning, there's room for
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billions of meaningful thoughts. I won't argue for exactly 2 billion versus 1.8 billion. It's
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not that kind of question. But I think any estimate that's reasonable will come out
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within, say, 100 billion and 100 million. So it's a lot.
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It would be interesting to map out for an individual human being the landscape of thoughts
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that they've sort of traveled. If you think of thoughts as a set of trajectories,
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what that landscape looks like? I mean, I've been recently really thinking about
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this Richard Dawkins idea of memes and just all these ideas and the evolution of ideas
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inside of one particular human mind and how they're then changed and evolved by interaction
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with other human beings. It's interesting to think about. So if you think the numbers, billions,
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you think there's also social interaction. So these aren't like there's interaction
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in the same way you have interaction with particles. There's interaction between human thoughts
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that perhaps that interaction in itself is fundamental to the process of thinking. Without
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social interaction, we would be stuck walking in a circle. We need the perturbation of other
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humans to create change in evolution. Once you bring in concepts of interactions and correlations
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and relations, then you have what's called a combinatorial explosion that the number of
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possibilities expands exponentially technically with the number of things you're considering.
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And it can easily, rapidly outstrip these billions of thoughts that we're talking about.
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So we definitely cannot buy brute force master complex situations and or think of all the
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possibilities in a complex situations. I mean, even something as relatively simple as chess
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is still something that human beings can't comprehend completely. Even the best players
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lose, still sometimes lose, and they consistently lose to computers these days. And in computer
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science, there's a concept of NP complete. So large classes of problems when you scale them up
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beyond a few individuals become intractable. And so that in that sense, the world is inexhaustible.
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But in that makes it beautiful that we can make any laws that generalize efficiently and well
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can compress all of that combinatorial complexity just like a simple rule that that itself is
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beautiful. It's a happy situation. And I think that that we can find general principles of sort
link |
00:28:43.600
of the operating system that are comprehensible, simple, extremely powerful, and let us control
link |
00:28:50.800
things very well and ask profound questions. And on the other hand, that the world is going
link |
00:28:57.120
to be inexhaustible. That once we start asking about relationships and how they evolve and
link |
00:29:05.440
social interactions, and we'll never have a theory of everything in any meaningful sense because
link |
00:29:12.240
of that. Of everything, everything. Truly everything is. Can I ask you about the Big Bang?
link |
00:29:19.840
So we talked about the space and time are really big. But then and we humans give a lot of meaning
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00:29:27.680
to the word space and time in our in our like daily lives. But then can we talk about this moment
link |
00:29:36.480
of beginning and how we're supposed to think about it? That at the moment of the Big Bang,
link |
00:29:42.400
everything was what like infinitely small. And then it just blew up. We have to be careful here
link |
00:29:49.760
because there's a common misconception that the Big Bang is like the explosion of a bomb in empty
link |
00:29:58.960
space that fills up the surrounding place. It is space. It is. Yeah. As we as we understand it,
link |
00:30:07.040
it's the fact, it's the fact or the hypothesis, but well supported up to a point that that
link |
00:30:17.840
everywhere in the whole universe, early in the history, matter came together into a very hot,
link |
00:30:26.480
very dense. If you run it backwards in time, matter comes together into a very hot, very dense,
link |
00:30:32.640
and yet very homogeneous plasma of all the different kinds of elementary particles and
link |
00:30:39.440
quarks and anti quarks and gluons and photons and electrons and anti electrons, everything,
link |
00:30:43.520
you know, all of that stuff, like really hot, really, really, really hot. We're talking about
link |
00:30:49.920
way, way hotter than the surface of the sun. Well, in fact, if you take the equations as we,
link |
00:30:59.440
as they come, the prediction is that the temperature just goes to infinity, but then the equations
link |
00:31:06.160
break down. We don't, you know, we don't, don't really, there are various,
link |
00:31:10.560
the equations become infinity equals infinity. So they don't feel that it's called a singularity.
link |
00:31:14.960
We don't really know this is running the equations backwards. So you can't really get a sensible
link |
00:31:21.200
idea of what happened before the Big Bang. We don't, you know, so we need different equations to
link |
00:31:26.160
address the very earliest moments. But so things were hotter and denser. We don't really know
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00:31:36.960
why things started out that way. We do, we have a lot of evidence that they did start out that way.
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00:31:44.240
But since most of the, you know, we don't get to visit there and do controlled experiments,
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00:31:55.440
most, most of the, most of the record is, is very, very processed. And we have to, we have to use
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00:32:02.000
very subtle techniques and powerful instruments to, to get information that has survived.
link |
00:32:10.480
Get closer and closer to the Big Bang.
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00:32:12.640
Get closer and closer to the, the beginning of things. And what's revealed there is that,
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00:32:22.080
as I said, there, there undoubtedly was a period when everything in the universe that we
link |
00:32:27.600
have been able to look at and understand, and that's consistent with everything, is
link |
00:32:36.880
the, was in a condition where it was much, much hotter and much, much denser,
link |
00:32:44.160
but still obeying the laws of physics as we know them today. And, and then you start with that.
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00:32:50.960
So all the matter is in equilibrium. And then with small quantum fluctuations and run it forward.
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00:32:59.440
And then it produces, at least in broad strokes, the universe we see around us today.
link |
00:33:06.400
Do you think we'll ever be able to, with the tools of physics, with the way sciences,
link |
00:33:12.480
with the way the human mind is, we'll ever be able to get to the moment of the Big Bang
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00:33:17.600
in our understanding or even the moment before the Big Bang? Can we understand what happened
link |
00:33:22.800
before the Big Bang? I'm, I'm optimistic, both that we'll be able to measure more, so observe more,
link |
00:33:33.440
and that we'll be able to figure out more. So they're very, very tangible prospects for
link |
00:33:40.960
observing the extremely early universe, so much, even much earlier than we can observe now,
link |
00:33:48.000
through looking at gravitational waves. Gravitational waves, since they interact so
link |
00:33:53.760
weakly with ordinary matter, sort of send an un, a minimally processed signal from the Big
link |
00:34:01.920
Bang. It's a very weak signal because it's traveled a long way and diffused over long spaces.
link |
00:34:07.920
But, but people are gearing up to try to detect gravitational waves that could have come from
link |
00:34:13.920
the early universe. Yeah, LIGO's incredible engineering project. It's the most sensitive,
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00:34:19.840
precise devices on earth. The fact that humans can build something like that is
link |
00:34:27.040
truly awe inspiring from an engineering perspective. Right. And, but these gravitational waves from
link |
00:34:32.640
the early universe will probably be of a much longer wavelength than LIGO is capable of sensing.
link |
00:34:39.920
So there's a beautiful project that's contemplated to put lasers in different part, different
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00:34:51.360
locations in the solar system. You know, we really, really separated by solar system scale
link |
00:34:57.840
differences like artificial planets or moons in different places and see the tiny motions of
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00:35:05.520
those relative to one another as a signal of radiation from the Big Bang. We can also maybe
link |
00:35:12.240
indirectly see the imprint of gravitational waves from the early universe on the photons,
link |
00:35:20.480
the, the microwave background radiation that is our present way of, of seeing into the earliest
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00:35:26.640
universe. But those, those photons interact much more strongly with matter. They're much more
link |
00:35:31.760
strongly processed. So they don't give us directly such an unprocessed view of the early universe,
link |
00:35:39.200
of the very early universe. But if gravitational waves leave some imprint on that as they move
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00:35:47.040
through, we could detect that too. And people are trying our, as we speak,
link |
00:35:52.080
working very hard towards, towards that goal. It's so exciting to think about a sensor the size
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00:35:59.280
of the solar system. Like, that would be a fantastic, I mean, that would be a pinnacle
link |
00:36:05.280
artifact of human endeavor to me. It would be such such an inspiring thing that just
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00:36:12.880
we want to know. And we go to these extraordinary lengths of making gigantic things that are also
link |
00:36:19.840
very sophisticated. Because what you're trying to do, you have to understand how they move. You
link |
00:36:24.880
have to understand the properties of light that they're being used, the interference between light
link |
00:36:30.720
and, and you have to be able to make the light with lasers and understand the quantum theory and
link |
00:36:35.840
get the timing exactly right. And it's an extraordinary endeavor involving all kinds
link |
00:36:41.520
of knowledge from the very strong, very small to the very large, and all in the service of
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00:36:46.640
curiosity and built on a grand scale. So yeah, it would make me proud to be a human if we did that.
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00:36:58.160
I love that you're inspired both by, by the power of theory and the power of experiments. So the
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00:37:03.200
both, both I think are exceptionally impressed that the human mind can come up with theories
link |
00:37:09.760
that give us a peek into how the universe works, but also construct tools that are way bigger
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00:37:16.800
than the, the evolutionary origins we came from. Right. And by the way, you know, the fact that
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00:37:22.400
we can design such things and they work, yeah, is an extraordinary demonstration that we really
link |
00:37:28.720
do understand a lot. And then in some ways, and it's our ability to answer questions that also
link |
00:37:36.800
leads us to be able to address more ambitious questions. So you mentioned that at the, at the
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00:37:42.160
big bang in the early days, things are pretty homogeneous. Yes. But here we are sitting on Earth
link |
00:37:51.600
to hairless apes, you could say with microphones in talking about the brief history of things you
link |
00:37:58.800
said it's much harder to describe Sweden than it is the universe. So there's a lot of complexity,
link |
00:38:05.200
there was a lot of interesting details here. So how does this complexity come to be, do you think?
link |
00:38:11.120
It seems like there's these pockets. Yeah. We don't know how rare of like
link |
00:38:16.400
where hairless apes emerge. Yeah. And then that came from the initial soup that was homogeneous.
link |
00:38:23.440
Was that, is that an accident? Well, we understand there, we understand in broad
link |
00:38:29.760
outlines how it could happen. We certainly don't understand why it happened exactly in the way it
link |
00:38:36.640
did. But, but, or, you know, there are certainly open questions about the origins of life and how
link |
00:38:44.320
inevitable the emergence of intelligence was and, and how that happened. But in the very broadest
link |
00:38:51.360
terms, the universe early on was quite homogeneous, but not completely homogeneous. There are,
link |
00:39:02.080
there were part in 10,000 fluctuations in density within this primordial plasma. And as time goes on,
link |
00:39:13.280
there's an instability which causes those density contrasts to increase. There's a gravitational
link |
00:39:21.120
instability where it's denser, the gravitational attractions are stronger. And so that brings
link |
00:39:26.400
in more matter and it gets even denser and so on and so on. So, so there's a natural tendency of
link |
00:39:33.200
matter to clump because of gravitational interactions. And then the equation is complicated.
link |
00:39:39.680
We have lots of things clumping together. Then, you know, then, then we know what the laws are,
link |
00:39:46.880
but we have to, to a certain extent, wave our hands about what, what, what happens. But
link |
00:39:53.280
basic understanding of chemistry says that if things and, and the physics of radiation tells us
link |
00:40:00.480
that if, as things start to clump together, they can radiate, give off some energy so they don't
link |
00:40:05.840
move, just they slow down. They, as a result, they lose energy, they can clump it together,
link |
00:40:10.960
cool down, form things like stars, form things like planets. And so in broad terms, there's no
link |
00:40:18.640
mystery. There's that, that's what the scenario, that's what the equations tell you should happen.
link |
00:40:24.720
But because it's a process involving many, many fundamental individual units,
link |
00:40:36.000
the, the application of the laws that govern simply individual units to these things is, is
link |
00:40:43.680
very delicate or, you know, computationally very difficult. And more profoundly, the equations
link |
00:40:51.520
have this probability of chaos or sensitivity to initial conditions, which tells you tiny
link |
00:40:56.560
differences in the initial state can lead to enormous differences in the subsequent behavior.
link |
00:41:02.320
So, so physics, fundamental physics at some point says, okay, chemists, biologists, this is your
link |
00:41:11.120
problem. And, and, and then again, in broad terms, we know how it's conceivable that, that humans
link |
00:41:22.960
and things like that can, can, that how complex structure can emerge. It's a matter of having
link |
00:41:32.240
the right kind of temperature and the right kind of stuff. So you need,
link |
00:41:36.800
you need to be able to make chemical bonds that are reasonably stable and be able to make complex
link |
00:41:44.720
structures. And we're very fortunate that carbon has this ability to make backbones and, and elaborate
link |
00:41:53.040
branching and things. So you can get complex things that we call biochemistry. And, and yet
link |
00:41:58.960
the bonds can be broken a little bit with the help of energetic injections from the sun. So you
link |
00:42:04.880
have to have both the possibility of changing, but also the possible, a useful degree of stability.
link |
00:42:10.400
And we know at that very, very broad level, physics can tell you that it's conceivable.
link |
00:42:17.680
If you want to know what actually, what, what's, what, what really happened, what really can
link |
00:42:23.600
happen, then you have to, then you have to work about to go to chemistry. If you have, if you
link |
00:42:27.600
want to know what actually happened, then you really have to consult the fossil record and
link |
00:42:32.240
biologists and so, but, but it's, so these, these ways of addressing the issue are complementary
link |
00:42:42.720
in a sense. They, they, they, they use different kinds of concepts. They use different languages
link |
00:42:52.320
and they address different kinds of questions, but they're, they're not inconsistent. They're just
link |
00:42:56.960
complementary. It's kind of interesting to think about those early fluctuations
link |
00:43:03.600
as our earliest ancestors. Yes, that's right. So it's far, it's amazing to think that, you know,
link |
00:43:13.040
this is the modern answer to the, or the modern version of what the Hindu philosophers had that
link |
00:43:24.400
art thou. If you ask what, okay, that, those, those little quantum fluctuations in the early
link |
00:43:30.800
universe are the seeds out of which complexity, including plausibly humans really evolve. You
link |
00:43:40.800
don't need anything else. That brings up the question of asking for a friend here. If there's,
link |
00:43:47.680
you know, other pockets of complexity, commonly called as alien intelligent civilizations out
link |
00:43:57.760
there. Well, we don't know for sure, but I, I have a strong suspicion that the answer is yes,
link |
00:44:05.600
because the, the one case we do have at hand to study here on earth, we sort of know what the
link |
00:44:16.480
conditions were that were helpful to life, the right kind of temperature, the right kind of star
link |
00:44:21.520
that, that keeps maintains that temperature for a long time, the liquid environment of water.
link |
00:44:28.320
And once those conditions emerged on earth, which was roughly four and a half billion years ago,
link |
00:44:35.920
it wasn't very long before what we call life started to leave relics. So we can find forms of
link |
00:44:45.360
life, primitive forms of life that are almost as old as the earth itself in the sense that once the
link |
00:44:51.440
earth became recent, it was, was turned from a, a very hot boiling thing and cooled off into a solid
link |
00:45:00.320
mass with, with water life emerged very, very quickly. So, so it seems that these general
link |
00:45:05.760
conditions for life are enough to, to make it happen relatively quickly. Now, the other lesson
link |
00:45:18.320
I would, I think that one can draw from this one example, it's dangerous to, to draw lessons from
link |
00:45:24.560
one example, but that's all we've got. And that, that the emergence of intelligent life is a different
link |
00:45:32.720
issue altogether. It, that took a long time and seems to have been pretty contingent.
link |
00:45:43.360
The, you know, the, for a long time, well, for most, most of the history of life, it was single
link |
00:45:51.360
celled things, you know, even multicellular life only rose about 600 million years ago so much
link |
00:46:00.800
after, you know, so, and the, the, and then intelligence is kind of a luxury, you know,
link |
00:46:10.320
a few things. Many more kinds of creatures have big stomachs and then big brains and,
link |
00:46:20.080
in fact, most, most, most have no brains at all in any reasonable sense that then,
link |
00:46:25.920
and the dinosaurs ruled for a long, long time and some of them were pretty smart, but they,
link |
00:46:32.720
they were at best bird brains because, you know, birds came from the dinosaurs and,
link |
00:46:38.880
and, and it could have stayed that way, you know, and then human, and the emergence of humans was
link |
00:46:45.120
very contingent and kind of a very, very recent development on evolutionary time scales. And
link |
00:46:52.000
you can argue about the level of human intelligence, but it's, you know, I think it's
link |
00:46:56.000
very impressive. That's what we're talking about. And it's very, it's very impressive and, and
link |
00:47:00.560
can ask these kinds of questions and discuss them intelligently. The, so I guess my, so this is a
link |
00:47:09.920
long winded answer or justification of my feeling is that the conditions for life in some form are
link |
00:47:25.680
probably satisfied in many, many places around the universe, even, and even within our galaxy.
link |
00:47:31.760
I'm not so sure about the emergence of intelligent life or the emergence of technological
link |
00:47:40.240
civilizations. That, that, that seems much more, much more contingent and special. And
link |
00:47:48.160
we might, it's conceivable to me that we're the only example in the galaxy. Although, yeah,
link |
00:47:55.360
I don't know one way or the other. I have different opinions on different days of the week.
link |
00:47:59.440
But one of the things that worries me in, in the spirit of being humble, that our particular
link |
00:48:06.320
kind of intelligence is not very special. So there's all kinds of different intelligences.
link |
00:48:13.600
And even more broadly, there could be many different kinds of life. So the basic definition,
link |
00:48:20.960
and I just had, I think somebody that you know, Sarah Walker, I just had a very long conversation
link |
00:48:26.400
with her about even just the very basic question of trying to define what is life from a physics
link |
00:48:33.200
perspective. Even that question within itself, I think one of the most fundamental questions
link |
00:48:38.080
in science and physics and everything is just trying to get a hold, trying to get some universal
link |
00:48:45.040
laws around the ideas of what is life. Because that kind of unlocks a bunch of things around
link |
00:48:50.320
life, intelligence, consciousness, all those kinds of things.
link |
00:48:53.280
I agree with you in a sense, but I think that's a dangerous question because
link |
00:48:59.440
the answer can't be any more precise than the question. And the question what is life
link |
00:49:07.840
kind of assumes that we have a definition of life and that it's a natural phenomena that
link |
00:49:13.280
can be distinguished. But really, there are edge cases like viruses and
link |
00:49:17.520
some people would like to say that electrons have consciousness. So you can't, if you really have
link |
00:49:26.720
fuzzy concepts, it's very hard to reach precise kinds of scientific answers. But I think there's
link |
00:49:35.120
a very fruitful question that's adjacent to it, which has been pursued in different forms for
link |
00:49:42.240
quite a while and is now becoming very sophisticated in reaching in new directions. And that is,
link |
00:49:51.040
what are the states of matter that are possible? So in high school or grade school, you learn
link |
00:49:58.960
about solids, liquids, and gases, but that really just scratches the surface of different ways that
link |
00:50:06.480
are distinguishable that matter can form into macroscopically different meaningful patterns
link |
00:50:16.080
that we call phasism. And then there are precise definitions of what we mean by phasism matter
link |
00:50:21.520
and that have been worked out fruitful over the decades. And we're discovering new states of
link |
00:50:28.320
matter all the time and kind of having to work at what we mean by matter. We're discovering the
link |
00:50:34.240
capabilities of matter to organize in interesting ways. And some of them, like liquid crystals,
link |
00:50:45.920
are important ingredients of life, our cell membranes are liquid crystals. And that's very
link |
00:50:52.240
important to the way they work. Recently, there's been a development in where we're talking about
link |
00:50:58.800
states of matter that are not static, but that have dynamics, that have characteristic patterns
link |
00:51:08.080
not only in space, but in time. These are called time crystals. And that's been a development
link |
00:51:13.120
that's just in the last decade or so. It's really flourishing. And so, is there a state of matter
link |
00:51:24.480
or a group of states of matter that corresponds to life? Maybe, but the answer can't be any
link |
00:51:33.680
more definite than the question. I mean, I gotta push back on the, those are just words.
link |
00:51:39.760
I mean, I disagree with you. The question points to a direction. The answer might be able to be
link |
00:51:47.920
more precise than the question, because just as you're saying that we could be discovering
link |
00:51:56.640
certain characteristics and patterns that are associated with a certain type of matter,
link |
00:52:02.720
macroscopically speaking. And that we can then be able to post facto say, let's assign the word
link |
00:52:12.480
life to this kind of matter. I agree with that completely. So, it's not a disagreement.
link |
00:52:19.680
It's very frequent in physics or in science that words that are in common use get refined and
link |
00:52:28.320
reprocessed into scientific terms. That's happened for things like force and energy.
link |
00:52:33.680
And so, in a way, we find out what the useful definition is or symmetry, for instance. And
link |
00:52:44.480
the common usage may be quite different from the scientific usage, but the scientific usage
link |
00:52:50.560
is special and takes on a life of its own. And we find out what the useful version of it is,
link |
00:52:57.280
what the fruitful version of it is. So, in that spirit, I think if we can identify
link |
00:53:10.720
states of matter or linked states of matter that can carry on processes of self reproduction
link |
00:53:21.120
and development and information processing, we might be tempted to classify those things as
link |
00:53:32.960
life. What can I ask you about the craziest one, which is the one we know maybe least about,
link |
00:53:41.360
which is consciousness, is it possible that there are certain kinds of matter would be able to
link |
00:53:45.520
classify as conscious meaning. So, there's the panpsychist, right, with the philosophers who
link |
00:53:55.440
kind of try to imply that all matter has some degree of consciousness and you can almost construct
link |
00:54:02.320
like a physics of consciousness. Again, we're in such early days of this, but nevertheless,
link |
00:54:10.240
it seems useful to talk about it. Is there some sense from a physics perspective to make sense
link |
00:54:16.320
of consciousness? Is there some hope? Well, again, consciousness is imprecise, a very imprecise word
link |
00:54:24.720
and loaded with connotations that I think we should, we don't want to start a scientific
link |
00:54:30.560
analysis with that, I don't think. It's often been important in science to start with simple
link |
00:54:39.440
cases and work up consciousness. I think what most people think of when you talk about consciousness
link |
00:54:47.440
is, okay, what am I doing in the world? This is my experience. I have a rich inner life and
link |
00:54:55.840
experience. And where is that in the equations? And I think that's a great question, a great,
link |
00:55:02.560
great question. And actually, I think I'm gearing up to try to address that in coming years.
link |
00:55:10.880
One version of asking that question, just as you said now, is what is the simplest
link |
00:55:16.560
formulation of that to study? I think I'm much more comfortable with the idea of studying
link |
00:55:22.000
self awareness as opposed to consciousness, because that sort of gets rid of the mystical
link |
00:55:27.680
aura of the thing. And self awareness is in simple, I think contiguous, at least
link |
00:55:38.880
with ideas about feedback. So if you have a system that looks at its own state and responds to it,
link |
00:55:46.960
that's a kind of self awareness. And more sophisticated versions could be like in
link |
00:55:55.520
information processing things, computers that look into their own internal state and do something
link |
00:56:01.280
about it. And I think that could also be done in neural nets. This is called recurrent neural
link |
00:56:09.840
nets, which are hard to understand and kind of a frontier. So I think understanding those
link |
00:56:17.200
and gradually building up a kind of profound ability to conceptualize different levels of
link |
00:56:31.280
self awareness. What do you have to not know? And what do you have to know? And when do you know
link |
00:56:35.680
that you don't know it? What do you think you know that you don't really know? I think
link |
00:56:42.000
clarifying those issues, when we clarify those issues and get a rich theory around
link |
00:56:50.480
self awareness, I think that will illuminate the questions about consciousness in a way that
link |
00:56:58.160
scratching your chin and talking about qualia and blah, blah, blah, blah is never going to do.
link |
00:57:04.160
Well, I also have a different approach to the whole thing. So there's from a robotics perspective,
link |
00:57:09.040
you can engineer things that exhibit qualities of consciousness without understanding
link |
00:57:17.600
the how things work. And from that perspective, you, it's like a backdoor,
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00:57:25.520
like enter through the psychology door. Precisely.
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00:57:28.640
That are causing a science door. I think we're on the same wavelength here. I think that,
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and let me just add one comment, which is, I think we should try to understand consciousness
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00:57:41.760
as we experience it in evolutionary terms and ask ourselves, why? Why does it happen?
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00:57:52.880
This thing seems useful. Why is it useful? Why is it useful?
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Question. We've got a conscious eye watch here.
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Interesting question. Thank you, Siri. Okay.
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I'll get back to you later.
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00:58:12.960
And I think what we're, I'm morally certain that what's going to emerge from analyzing
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recurrent neural nets and robotic design and advanced computer design is that having this kind
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of looking at the internal state in a structured way that, that doesn't look at everything.
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00:58:37.680
It's kind of, it's encapsulated, looks at highly processed information and very selective and makes
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00:58:43.040
choices without knowing how they're made. So there'll also be an unconscious. I think that,
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that is going to be, turn out to be really essential to doing efficient information processing.
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00:58:55.360
And that's why it evolved because it's, it's, it's helpful in, because brains come at a high cost.
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So there has to be, there has to be a good why.
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And there's a reason, yeah, they're rare in evolution.
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00:59:12.560
And big brains are rare in evolution. And they, they come at a big cost. You mean, if you, you,
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you, they, they, they have high metabolic demands. They require, you know, very active lifestyle,
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00:59:30.480
warm bloodedness in, and take, take away from the ability to support metabolism of digestion.
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00:59:38.960
And so it's, it's, it comes at a high cost. It has to, it has to pay back.
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00:59:44.160
Yeah. I think it has a lot of value in social interaction. So I actually, I'm spending the
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rest of the day today and with our friends that are, our legged friends in robotic form at Boston
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00:59:57.440
Dynamics. And I think, so my probably biggest passion is human robot interaction. And it,
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01:00:06.080
it seems that consciousness from the perspective of the robot is very useful
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01:00:11.840
to improve the human robot interaction experience.
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01:00:16.480
The first, the display of consciousness, but then to me, there's a gray area between the
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01:00:20.640
display of consciousness and consciousness itself. If you think of consciousness from an
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01:00:25.120
evolutionary perspective, it seems like a useful tool in human communication. So.
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01:00:29.760
Yes. It's certainly, well, whatever consciousness is will turn out to be. I think addressing it
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01:00:37.280
through its use and working up from simple cases and also working up from engineering experience
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01:00:45.600
in trying to do efficient computation, including efficient management of social interactions
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01:00:53.280
is going to really shed light on these questions. As I said, in a way that sort of musing abstractly
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01:00:59.520
about consciousness never would. So as I mentioned, I talked to Sarah Walker and first of all, she
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01:01:05.280
says hi, spoke with a highly review. One of her concerns about physics and physicists and humans
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01:01:12.320
is that we may not fully understand the system that we're inside of, meaning
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01:01:20.400
like there may be limits to the kind of physics we do in trying to understand the system of which
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01:01:27.040
we're part of. So like the observer is also the observed. In that sense, it seems like the
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01:01:39.520
our tools of understanding the world. I mean, this is mostly centered around the questions of
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01:01:44.800
what is life, trying to understand the patterns that are characteristic of life and intelligence,
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01:01:51.120
all those kinds of things. We're not using the right tools because we're in the system. Is there
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01:01:58.080
something that resonates with you there? Well, yes, we do have limitations, of course,
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01:02:08.400
in the amount of information we can process. On the other hand, we can get help from our
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01:02:15.120
silicon friends. And we can get help from all kinds of instruments that make up for our perceptual
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01:02:23.200
deficits. And we have to, and we can use at a conceptual level, we can use different kinds
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01:02:31.840
of concepts to address different kinds of questions. So I'm not sure exactly what problem
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01:02:38.960
she's talking about. It's a problem akin to an organism living in a 2G plane, trying to
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01:02:45.840
understand a three dimensional world. Well, we can do that. In fact, for practical purposes,
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01:02:53.280
most of our experience is two dimensional. It's hard to move vertically. And yet we've produced
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01:02:59.360
conceptually a three dimensional symmetry. And in fact, four dimensional space time.
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01:03:04.080
So, by thinking in appropriate ways and using instruments and getting consistent
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01:03:12.880
accounts and rich accounts, we find out what concepts are necessary. And I don't see any end
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01:03:24.480
inside of the process or any showstoppers because let me give you an example. I mean,
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01:03:32.320
for instance, QCD, our theory of the strong interaction has nice equations, which I helped
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01:03:38.960
to discover. What's QCD? Quantum chromodynamics. So it's our theory of the strong interaction,
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01:03:47.360
the interaction that is responsible for nuclear physics. So it's the interaction that governs
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01:03:52.960
how quarks and gluons interact with each other and make protons and neutrons and all the strong,
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01:03:59.920
the related particles and many things in physics. That's one of the four basic forces of nature,
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01:04:07.840
as we presently understand it. And so we have beautiful equations, which we can test
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01:04:18.560
in very special circumstances using at high energies, at accelerators. So we
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01:04:25.840
be certain that these equations are correct. Prizes are given for it. And so people try
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01:04:30.960
to knock it down and they can't. But the situations in which we can calculate the
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01:04:43.040
consequences of these equations are very limited. So for instance, no one has been able to demonstrate
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01:04:51.360
that this theory, which is built on quarks and gluons, which you don't observe,
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01:05:00.960
actually produces protons and neutrons and the things you do observe. This is called the
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01:05:05.040
problem of confinement. So no one's been able to prove that analytically in a way that a human
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01:05:11.840
can understand. On the other hand, we can take these equations to a computer, to gigantic computers
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01:05:18.960
and compute. And by God, you get the world from it. So these equations in a way that we don't
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01:05:31.040
understand in terms of human concepts, we can't do the calculations, but our machines can do them.
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01:05:38.960
So with the help of what I like to call our silicon friends and their descendants in the future,
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01:05:46.000
we can understand in a different way that allows us to understand more.
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01:05:52.880
But I don't think we'll ever, no human is ever going to be able to solve those equations in
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01:05:59.120
the same way. But I think that when we find limitations to our natural abilities, we can try
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01:06:10.880
to find workarounds. And sometimes that's appropriate concepts. Sometimes it's appropriate
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01:06:16.160
instruments. Sometimes it's a combination of the two. But I think it's premature to get
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01:06:25.040
defeatist about it. I don't see any logical contradiction or paradox or limitation that
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01:06:35.200
that will bring this process to a halt. Well, I think the idea is to continue thinking outside
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01:06:41.280
of the box in different directions, meaning just like how the math allows us to think in multiple
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01:06:46.560
dimensions outside of our perception system, sort of thinking, coming up with new tools of
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01:06:55.600
mathematical computation or all those kinds of things to take different perspectives on our
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01:07:03.280
universe. Well, I'm all for that. And I kind of have even elevated it into a principle, which is
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01:07:09.120
of complementarity, following Bohr that you need different ways of thinking even about the same
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01:07:17.520
things in order to do justice to their reality and answer different kinds of questions about them.
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01:07:23.760
I mean, we've several times alluded to the fact that human beings are hard to understand
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01:07:29.520
and the concepts that you use to understand human beings, if you want to prescribe drugs for them
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01:07:36.960
or see what's going to happen if they move very fast or get exposed to radiation. And so that
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01:07:44.960
requires one kind of thinking that's very physical based on the fact that the materials that we're
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01:07:53.520
made out of. On the other hand, if you want to understand how a person is going to behave in
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01:07:58.720
a different kind of situation, you need entirely different concepts from psychology. And there's
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01:08:06.880
nothing wrong with that. You can have very different ways of addressing the same material
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01:08:11.040
that are useful for different purposes, right? Can you describe this idea which is fascinating of
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01:08:16.720
complementarity a little bit, sort of, first of all, what state is the principle? What is it?
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01:08:25.840
And second of all, what are good examples starting from quantum mechanics? You used to mention
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01:08:31.360
psychology. Let's talk about this more. It's really one in your new book, one of the most
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01:08:35.200
fascinating ideas, actually. I think it's a wonderful, yeah, it's sort of, to me, it's,
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01:08:40.880
well, it's the culminating chapter of the book. And I think since the whole book is about the
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01:08:47.200
big lessons or big takeaways from profound understanding of the physical world that we've
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01:08:53.600
understood, that we've achieved, including that it's mysterious in some ways, the,
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01:09:00.960
this was the final overarching lesson, complementarity. And
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01:09:11.600
it's a approach. So unlike some of these other things, which are just facts about the world,
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01:09:20.480
like the world is both big and small in different sessions, and is big, but we're not small,
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01:09:25.760
things we talked about earlier, and the fact that the universe is comprehensible and how
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01:09:31.440
complexity could emerge from simplicity. And so those things are, in some, in the broad sense,
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01:09:37.760
facts about the world, complementarity is more an attitude towards the world that is encouraged
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01:09:44.240
by the facts about the world. And it's the idea, the concept of the approach that or the realization
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01:09:55.760
that it can be appropriate and useful and inevitable and unavoidable to use very different
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01:10:04.400
descriptions of the same object or the same system or the same situation to answer different kinds of
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01:10:14.080
questions that may be very different and even mutually uninterpretable, imutably
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01:10:25.600
incomprehensible. But both correct somehow. But both correct and sources of different kinds of
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01:10:31.920
insight. Which is so weird. Yeah, well. But it seems to work in so many cases. It works in many cases,
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01:10:37.680
and I think it's a deep fact about the world and how we should approach it. It's most rigorous form
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01:10:48.480
where it's actually a theorem, if quantum mechanics is correct, occurs in quantum mechanics,
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01:10:55.280
where the primary description of the world is in terms of wave functions. But let's not talk
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01:11:04.000
about the world. Let's just talk about a particle, an electron. It's the primary description of that
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01:11:11.360
electron is its wave function. And the wave function can be used to predict where it's
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01:11:20.240
going to be. And if you observe, it'll be in different places with different probabilities.
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01:11:25.600
Or how fast it's moving. And it'll also be moving in different ways with different probabilities.
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01:11:32.560
That's what quantum mechanics says. And you can predict either set of probabilities. What's going
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01:11:39.600
to happen if I make an observation of the position or the velocity. So the wave function gives you
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01:11:49.840
ways of doing both of those. But to do it, to get those predictions, you have to process the wave
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01:11:55.520
function in different ways. You process it one way for position and a different way for momentum.
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01:12:01.360
And those ways are mathematically incompatible. It's like you have a stone and you can sculpt it
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01:12:09.360
into Venus de Milo where you can sculpt it into David, but you can't do both. And that's an example
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01:12:18.960
of complementarity. But to answer different kinds of questions, you have to analyze the system in
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01:12:24.560
different ways that are mutually incompatible, but both valid to answer different kinds of questions.
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01:12:32.640
So in that case, it's a theorem. But I think it's a much more widespread phenomena that applies to
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01:12:39.520
many cases where we can't prove it as a theorem. But it's a piece of wisdom, if you like, and
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01:12:46.640
it appears to be a very important insight. And if you ignore it, you can get very confused and
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01:13:00.640
misguided. Do you think this is a useful hack for ideas that we don't fully understand?
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01:13:09.840
Or is this somehow a fundamental property of all or many ideas that you can take
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01:13:17.520
multiple perspectives and they're both true? Well, I think it's both.
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01:13:24.000
So it's both the answer to all questions. That's right. It's not either or. It's both.
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01:13:28.800
It's paralyzing to think that we live in a world that's fundamentally surrounded by complementary
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01:13:36.720
ideas. Because we somehow want to attach ourselves to absolute truths. And absolute
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01:13:46.240
truths certainly don't like the idea of complementarity.
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01:13:50.000
Yes. Einstein was very uncomfortable with complementarity. In a broad sense, the famous
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01:13:55.680
Bohr Einstein debates revolved around this question of whether the complementarity that is a foundational
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01:14:06.800
feature of quantum mechanics as we have it was, is a permanent feature of the universe and our
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01:14:17.280
description of nature. And so far, quantum mechanics wins and it's gone from triumph to triumph.
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01:14:26.400
Whether complementarity is rock bottom, I guess you can never be sure. But it looks awfully good
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01:14:34.080
and it's been very successful. And certainly, complementarity has been extremely useful and
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01:14:40.400
fruitful in that domain, including some of Einstein's attempts to challenge it with
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01:14:51.200
like the famous Einstein Podolsky Rosen experiment turned out to be confirmations
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01:14:58.240
that have been useful in themselves. But so thinking about these things was fruitful,
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01:15:05.040
but not in the way that Einstein hoped. So as I said, in the case of quantum mechanics and this
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01:15:24.640
dilemma or dichotomy between processing the wave function in different ways,
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01:15:29.120
it's a theorem. They're mutually incompatible and that the physical correlate of that is the
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01:15:32.960
Heisenberg uncertainty principle that you can't have position and momentum determined at once.
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01:15:41.520
But in other cases, like one that I like to think about is or like to point out as an example is
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01:15:50.640
free will and determinism. It's much less of a theorem and more a kind of way of thinking about
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01:16:05.680
things that I think is reassuring and avoids a lot of unnecessary quarreling and confusion.
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01:16:15.840
The quarreling I'm okay with and the confusion I'm okay with, I mean, people debate about difficult
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01:16:20.400
ideas. But the question is whether it could be almost a fundamental truth. I think it is a
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01:16:27.280
fundamental truth. That free will is both an illusion and not. Yes, I think that's correct.
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01:16:35.920
The reason why people say quantum mechanics is weird and complementarity is a big part of that.
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01:16:42.480
To say that our actual whole world is weird, the whole hierarchy of the universe is weird in this
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01:16:52.400
kind of particular way, and it's quite profound, but it's also humbling because it's like we're
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01:17:04.800
never going to be on sturdy ground in the way that humans like to be. It's like you have to
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01:17:10.000
embrace that, well, this whole thing is like unsteady mess. It's one of many lessons in humility
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01:17:21.920
that we run into in profound understanding of the world. I mean, the Copernican revolution
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01:17:29.920
was one that the earth is not the center of the universe. Darwinian evolution is another that humans
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01:17:38.240
are not the pinnacle of God's creation. The apparent result of deep understanding of physical
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01:17:56.880
reality that the mind emerges from matter and there's no call on special life forces or souls.
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01:18:09.200
These are all lessons in humility, and I actually find complementarity a
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01:18:16.240
liberating concept. There's a story about Dr. Johnson and he's talking with Boswell,
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01:18:32.560
and they were discussing a sermon that they'd both heard, and the sort of culmination of the
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01:18:40.560
sermon was the speaker saying, I accept the universe, and Dr. Johnson said, well, he'd damn
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01:18:48.400
well better, and there's a certain joy in accepting the universe because it's mind expanding,
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01:18:56.960
and to me, complementarity also suggests tolerance, suggests opportunities for understanding
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01:19:15.440
things in different ways that add to, rather than detract from understanding.
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01:19:24.320
I think it's an opportunity for mind expansion and demanding that there's only one way to think
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01:19:33.440
about things can be very limiting. On the free will one, that's a trippy one though.
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01:19:39.680
To think like I am the decider of my own actions and at the same time I'm not is tricky to think
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01:19:49.360
about, but it does seem to be some kind of profound truth in that. Well, I think it is tied
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01:19:55.840
up, it will turn out to be tied up when we understand things better with these issues of
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01:20:01.600
self awareness and where we get what we perceive as making choices, what does that really mean,
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01:20:07.920
and what's going on under the hood, but I'm speculating about a future understanding that's
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01:20:15.120
not in place at present. Your sense there will always be, as you dig into the self awareness
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01:20:22.320
thing, there'll always be some places where complementarity is going to show up.
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01:20:26.560
Oh, definitely. Yeah. I mean, there will be, how should I say, there'll be kind of a God's
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01:20:32.720
eye view, which sees everything that's going on in the computer or the brain, and then there's
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01:20:40.720
the brain's own view or the central processor or whatever it is, what we call the self, the
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01:20:49.360
consciousness, that's only aware of a very small part of it. And those are very different.
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01:20:56.320
So the God's eye view can be deterministic while the self view
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01:21:02.800
sees free will. I'm pretty sure that's how it's going to work out, actually. But as it stands,
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01:21:13.760
free will is a concept that we definitely, at least I feel I definitely experience,
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01:21:19.120
I can choose to do one thing than another, and other people I think are sufficiently similar
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01:21:24.400
to me that I trust that they feel the same way. And it's an essential concept in psychology and
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01:21:33.680
law and so forth. But at the same time, I think that mind emerges from matter, and that there's
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01:21:43.840
an alternative description of matter that's up to subtleties about quantum mechanics,
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01:21:50.960
which I don't think are relevant here, really is deterministic.
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01:21:55.920
Let me ask you about some particles. Okay. First, the absurd question,
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01:22:00.720
almost like a question that Plato would ask, what is the smallest thing in the universe?
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01:22:08.720
As far as we know, the fundamental particles out of which we build our most successful
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01:22:16.800
description of nature are points. They have zero, they don't have any internal structure.
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01:22:26.960
So that's as small as can be. So what does that mean operationally? That means that they obey
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01:22:36.400
equations that describe entities that are singular concentrations of energy, momentum,
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01:22:46.720
angular momentum, the things that particles have, but localized at individual points.
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01:22:53.360
Now, that mathematical structure is only revealed partially in the world because to
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01:23:02.000
process the wave function in a way that accesses information about the precise position of things,
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01:23:10.080
you have to apply a lot of energy, and that's an idealization that you can apply infinite
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01:23:15.840
amount of energy to determine a precise position. But at the mathematical level,
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01:23:23.440
we build the world out of particles that are points.
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01:23:26.320
So do they actually exist? And what are we talking about? So let me ask,
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01:23:30.480
sort of, do quarks exist? Yes. Do electrons exist? Yes. Do photons exist? Yes.
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01:23:37.760
But what does it mean for them to exist? Okay. So, well, the hard answer to that,
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01:23:43.280
the precise answer is that we construct the world out of equations that contain entities that are
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01:23:53.920
reproducible, that exist in vast numbers throughout the universe, that have definite properties of
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01:24:05.200
mass, spin, and a few others, that we call electrons. And what an electron is, is defined
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01:24:16.080
by the equations that it satisfies, theoretically, and we find that there are many, many exemplars of
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01:24:26.080
that entity in the physical world. So in the case of electrons, we can, you know,
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01:24:32.560
isolate them and study them in individual ones in great detail. We can check that they all
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01:24:38.400
actually are identical. And that's why chemistry works. And yes, so in that case,
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01:24:48.240
it's very tangible. Similarly with photons, you can study them individually, the units of light.
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01:24:56.400
And nowadays, it's very practical to study individual photons and determine their
link |
01:25:02.160
spin and their other basic properties and check out the equations in great detail.
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01:25:10.960
For quarks and gluons, which are the other two main ingredients of our model of matter,
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01:25:20.160
that's so successful, it's a little more complicated because the quarks and gluons
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01:25:24.960
that appear in our equations don't appear directly as particles you can isolate
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01:25:33.360
and study individually. They always occur within what are called bound states or
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01:25:41.840
structures like protons. A proton, roughly speaking, is composed of three quarks and a
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01:25:48.080
lot of gluons. But we can detect them in a remarkably direct way actually nowadays.
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01:25:53.680
Whereas at relatively low energies, the behavior of quarks is complicated,
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01:26:00.720
at high energies, they can propagate through space relatively freely
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01:26:08.000
for a while. And we can see their tracks. So ultimately, they get recaptured into protons
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01:26:14.640
and other mesons and funny things. But for a short time, they propagate freely. And while that
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01:26:21.680
happens, we can take snapshots and see their manifestations. Actually, this kind of thing
link |
01:26:30.960
is exactly what I got the Nobel Prize for, predicting that this would work. And similarly
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01:26:35.600
for gluons, although you can't isolate them as individual particles and study them in the same
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01:26:42.480
way we study electrons, you can use them theoretically as entities out of which you
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01:26:52.960
build tangible things that we actually do observe. But also, you can, at accelerators,
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01:27:02.880
at high energy, you can liberate them for brief periods of time and get convincing evidence
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01:27:13.360
and you can get convincing evidence that they were there and have the properties that we wanted
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01:27:18.800
them to have. Can we talk about asymptotic freedom, this very idea that you want the
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01:27:22.720
Nobel Prize for? Yeah. So it describes a very weird effect to me. The weird in the following
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01:27:32.720
way. So the way I think of most forces or interactions, the closer you are, the stronger
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01:27:42.480
the effect, the stronger the force. With quarks, the closer they are, the less the strong interaction.
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01:27:53.840
And in fact, they basically act like free particles when they're very close.
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01:28:00.480
That's right. But this requires a huge amount of energy. Can you describe me,
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01:28:08.320
why? How does this even work? How weird it is? A proper description must bring in
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01:28:17.040
quantum mechanics and relativity. So a proper description and equations. So a proper description
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01:28:26.480
really is probably more than we have time for and require quite a bit of patience on your part.
link |
01:28:35.760
How does relativity come into play? Wait. Oh, relativity is important because
link |
01:28:42.560
when we talk about trying to think about short distances, we have to think about
link |
01:28:52.560
a very large momenta and very large momenta are connected to very large energy in relativity.
link |
01:28:59.120
And so the connection between how things behave at short distances and how things behave at high
link |
01:29:04.800
energy really is connected through relativity in sort of a slightly backhanded way. Quantum
link |
01:29:13.280
mechanics indicates that short to get to analyze short distances, you need to bring in probes that
link |
01:29:24.000
carry a lot of momentum. This again is related to uncertainty because it's the fact that you
link |
01:29:31.200
have to bring in a lot of momentum that interferes with the possibility of determining
link |
01:29:38.240
position and momentum at the same time. If you want to determine position,
link |
01:29:41.840
you have to use instruments that bring in a lot of momentum. And because of that,
link |
01:29:47.200
those same instruments can't also measure momentum because they're disturbing the momentum.
link |
01:29:53.520
And then the momentum brings in energy. So that there's also the effect that asymptotic freedom
link |
01:29:59.520
comes from the possibility of spontaneously making quarks and gluons for short amounts of time that
link |
01:30:12.560
fluctuate into existence and out of existence. And the fact that that can be done with a very
link |
01:30:22.320
little amount of energy and uncertainty and energy translates into uncertainty and time. So if you
link |
01:30:28.160
do that for a short time, you can do that. Well, it's all comes in a package. So I told you it
link |
01:30:36.960
would take a while to really explain. But the results can be understood. I mean,
link |
01:30:44.160
we can state the results pretty simply, I think. So in everyday life, we do encounter some forces
link |
01:30:54.320
that increase with distance and kind of turn off at short distances. That's the way rubber bands
link |
01:31:00.480
work, if you think about it. If you pull them hard, they resist, but they get flabby if the rubber
link |
01:31:09.840
band is not pulled. And so there are that can happen in the physical world. But what's really
link |
01:31:18.560
difficult is to see how that could be a fundamental force that's consistent with everything else we
link |
01:31:23.440
know. And that's what asymptotic freedom is. It says that there's a very particular kind
link |
01:31:33.440
of fundamental force that involves special particles called gluons with very special
link |
01:31:39.120
properties that enables that kind of behavior. So at the time we did our work, there were
link |
01:31:47.520
experimental indications that quarks and gluons did have this kind of property, but
link |
01:31:55.280
there were no equations that were capable of capturing it. And we found the equations and
link |
01:32:01.440
showed how they work and showed how they that they were basically unique. And this led to a
link |
01:32:07.360
complete theory of how the strong interaction works, which is the quantum chromodynamics
link |
01:32:12.880
we mentioned earlier. So that's the phenomenon that quarks and gluons interact very, very
link |
01:32:24.160
weakly when they're close together. That's connected through relativity with the fact
link |
01:32:29.680
that they also interact very, very weakly at high energies. So at high energies,
link |
01:32:36.240
the simplicity of the fundamental interaction gets revealed. At the time we did our work,
link |
01:32:42.560
the clues were very subtle, but nowadays at what are now high energy accelerators,
link |
01:32:48.720
it's all obvious. So we would have had a much, well, somebody would have had a much easier time.
link |
01:32:53.520
20 years later, looking at the data, you can sort of see the quarks and gluons. As I mentioned,
link |
01:32:59.200
they leave these short tracks that would have been much, much easier. But from fundamental
link |
01:33:05.040
we, from fundamental, from indirect clues, we were able to piece together enough to make
link |
01:33:11.440
that behavior a prediction rather than a post diction, right?
link |
01:33:15.680
So it becomes obvious at high energies.
link |
01:33:17.840
It becomes very obvious. When we first did this work, it was frontiers of high energy
link |
01:33:24.080
physics and at big international conferences, there would always be sessions on testing QCD and
link |
01:33:30.960
whether this proposed description of the strong interaction was in fact correct and so forth.
link |
01:33:37.600
And it was very exciting. But nowadays, the same kind of work,
link |
01:33:44.720
but much more precise with calculations to more accuracy and experiments that are much more
link |
01:33:51.520
precise and comparisons that are very precise. Now it's called calculating backgrounds because
link |
01:34:01.440
people take this for granted and want to see deviations from the theory, which would be
link |
01:34:07.520
which would be the new discoveries.
link |
01:34:09.680
Yeah, the cutting edge becomes a foundation, the foundation becomes boring. Yes.
link |
01:34:13.280
Is there some, for basic explanation purposes, is there something to be said about
link |
01:34:21.520
strong interactions in the context of the strong nuclear force for the attraction
link |
01:34:27.920
between protons and neutrons versus the interaction between quarks within protons itself?
link |
01:34:35.280
Well, quarks and gluons have the same relation basically to nuclear physics as electrons and
link |
01:34:45.600
photons have to atomic and molecular physics. So atoms and photons are the dynamic entities that
link |
01:34:56.960
really come into play in chemistry and atomic physics. Of course, you have to add the atomic
link |
01:35:02.560
nuclei, but those are small and relatively inert, really the dynamical part. And for most purposes
link |
01:35:11.360
of chemistry, you just say that you have this tiny little nucleus, which QCD gives you. Don't
link |
01:35:17.120
worry about it. It's there. The real action is the electrons moving around and exchanging and
link |
01:35:23.360
things like that. But we want it to understand the nucleus too. So atoms are sort of quantum
link |
01:35:34.720
mechanical clouds of electrons held together by electrical forces, which is photons, and then
link |
01:35:39.840
this radiation, which is another aspect of photons. That's where all the fun happens is
link |
01:35:44.480
the electrons and photons and all that kind of stuff. Yeah, that's right. And the nucleus are
link |
01:35:48.240
kind of the, well, they're necessary, they give the positive charge and most of the mass of matter.
link |
01:35:56.880
But they don't, since they're so heavy, they don't move very much in chemistry. And
link |
01:36:06.240
I'm oversimplifying drastically. They're not contributing much to the interaction.
link |
01:36:12.080
For most purposes in chemistry, you can just idealize them as concentrations of positive mass
link |
01:36:16.880
and charge that you don't have to look inside. But people are curious what's inside. And that was
link |
01:36:27.840
a big thing on the agenda of 20th century physics starting in the 19, well, starting with the 20th
link |
01:36:33.920
century and unfolding throughout of trying to understand what forces held the atomic nucleus
link |
01:36:41.040
together, what it was and so on. Anyway, the story that emerges from QCD is that
link |
01:36:53.040
very similar to the way that, well, broadly similar to the way that
link |
01:36:59.040
clouds of electrons held together by electrical forces give you atoms and ultimately molecules,
link |
01:37:06.960
protons and neutrons are like atoms made now out of quarks, quark clouds held together by
link |
01:37:17.840
gluons, which are like the photons that give the electric forces. But this is giving a different
link |
01:37:24.560
force, the strong force. And the residual forces between protons and neutrons that
link |
01:37:32.160
are left over from the basic binding are like the residual forces between atoms that give molecules,
link |
01:37:41.200
but in the case of protons and neutrons, it gives you atomic nuclei.
link |
01:37:45.360
So again, for definitional purposes, QCD quantum chromodynamics is basically the physics of
link |
01:37:52.640
strong interaction. Yeah, we now understand what I think most physicists would say it's the theory
link |
01:37:59.520
of quarks and gluons and how they interact. But it's a very precise, and I think it's
link |
01:38:07.280
fair to say very beautiful theory based on mathematical symmetry of a high order.
link |
01:38:14.640
And another thing that's beautiful about it is that it's kind of
link |
01:38:18.800
in the same family as electrodynamics, the conceptual structure of the equations are
link |
01:38:30.320
very similar. They're based on having particles that respond to charge in a very symmetric way.
link |
01:38:37.040
In the case of electrodynamics, it's photons that respond to electric charge. In the case of
link |
01:38:43.040
quantum chromodynamics, there are three kinds of charge that we call colors,
link |
01:38:46.720
but they're nothing like colors. They really are like different kinds of charge.
link |
01:38:51.200
But they rhyme with the same kind of, like it's similar kind of dynamics.
link |
01:38:56.480
Similar kind of dynamics. I like to say that QCD is like QED on steroids.
link |
01:39:02.720
And instead of one photon, you have eight gluons. Instead of one charge, you have three color
link |
01:39:08.000
charges. But there's a strong family resemblance.
link |
01:39:11.280
But the context in which QCD does this thing is it's much higher energies.
link |
01:39:19.200
Like that's where it comes from. Well, it's a stronger force. So that
link |
01:39:23.200
to access how it works and kind of pry things apart, you have to inject more energy.
link |
01:39:30.240
And so that gives us, in some sense, a hint of how things were in the earlier universe.
link |
01:39:39.280
Yeah. Well, in that regard, asymptotic freedom is a tremendous blessing because it means
link |
01:39:45.520
things get simpler at high energy. And the universe was born free.
link |
01:39:50.000
Born free. That's very good. Yes. The universe was born.
link |
01:39:53.440
So in atomic physics, I mean, a similar thing happens in the theory of stars.
link |
01:39:59.280
Stars are hot enough that the interactions between electrons and photons, they're liberated.
link |
01:40:07.280
They don't form atoms anymore. They make a plasma, which in some ways is simpler to understand.
link |
01:40:12.080
You don't have complicated chemistry. And in the early universe, according to QCD,
link |
01:40:18.000
similarly, atomic nuclei dissolved into the constituent quarks and gluons, which are moving
link |
01:40:23.280
around very fast and interacting in relatively simple ways. And so this opened up the early
link |
01:40:29.920
universe to scientific calculation. Can I ask you about some other weird particles
link |
01:40:35.600
that make up our universe? What are axions? And what is the strong CP problem?
link |
01:40:42.480
Okay. So let me start with what the strong CP problem is.
link |
01:40:48.880
First of all, well, C is charge conjugation, which is the transformation,
link |
01:40:57.360
the notional transformation, if you like, that changes all particles into their antiparticles.
link |
01:41:02.320
And the concept of C symmetry, charge conjugation symmetry, is that if you do that,
link |
01:41:13.040
you find the same laws would work. So the laws are symmetric if the behavior that
link |
01:41:20.800
particles exhibit is the same as the behavior you get with all their antiparticles.
link |
01:41:26.800
And P is parity, which is also called spatial inversion. It's basically looking at a mirror
link |
01:41:37.600
universe and saying that the laws that are obeyed in a mirror universe, the mirror images obey the
link |
01:41:45.920
same laws as the sources of their images. There's no way of telling left from right, for instance,
link |
01:41:52.720
that the laws don't distinguish between left and right. Now, in the mid 20th century, people
link |
01:42:00.640
discovered that both of those are not quite true. Really, the equation that the mirror universe,
link |
01:42:09.040
the universe that you see in a mirror is not going to obey the same laws as the
link |
01:42:18.960
universe that we actually interpret. You would be able to tell if you did the right kind of
link |
01:42:28.240
experiments, which was the mirror and which was the real thing. Anyway, that...
link |
01:42:34.640
Just the parity and they show that the parity doesn't necessarily hold.
link |
01:42:37.760
It doesn't quite hold. And examining what the exceptions are turned out to be to lead to
link |
01:42:46.080
little kinds of insight about the nature of fundamental interactions, especially the properties
link |
01:42:50.640
of neutrinos and the weak interaction. It's a long story, but it's a very...
link |
01:42:55.360
So you just define the C and the P, the conjugation, the charge conjugation.
link |
01:42:59.360
Now that I've done that, I want to shove them off.
link |
01:43:03.840
Because it's easier to talk about T, which is time reversal symmetry. We have very good reasons to
link |
01:43:10.560
think CPT is an accurate symmetry of nature. It's on the same level as relativity and quantum
link |
01:43:19.760
mechanics, basically. So that better be true. So it's symmetric when you do conjugation parity
link |
01:43:27.440
in time. And time and space reversal. If you do all three, then you get the same physical
link |
01:43:34.000
consequences. But that means that CP is equivalent to T. But what's observed in the world is that
link |
01:43:42.080
T is not quite an accurate symmetry of nature, either. So most phenomena at the fundamental
link |
01:43:51.440
level, so interactions among elementary particles and the basic gravitational interaction,
link |
01:43:57.120
if you ran them backwards in time, you'd get the same laws. So this time, we don't talk about
link |
01:44:10.800
a mirror, but we talk about a movie. If you take a movie and then run it backwards,
link |
01:44:18.640
that's the time reversal. It's good to think about a mirror in time.
link |
01:44:23.280
Yes, like a mirror in time. If you run the movie backwards, it would look very strange if you
link |
01:44:30.720
were looking at complicated objects and a Charlie Chaplin movie or whatever. It would look very
link |
01:44:37.840
strange if you ran it backwards in time. But at the level of basic interactions, if you were able
link |
01:44:44.720
to look at the atoms and the quarks involved, they would obey the same laws to a very good
link |
01:44:51.120
approximation, but not exactly. So not exactly. That means you could tell.
link |
01:44:55.840
You could tell, but you'd have to do very, very subtle experiments with that high energy
link |
01:45:03.040
accelerators to take a movie that looked different when you ran it backwards. This was a discovery
link |
01:45:10.160
by two great physicists named Jim Cronin and Val Fitch in the mid 1960s. Previous to that,
link |
01:45:21.280
over all the centuries of development of physics with all its precise laws, they did seem to have
link |
01:45:26.240
this gratuitous property that they looked the same if you run the equations backwards. It's
link |
01:45:33.360
kind of an embarrassing property, actually, because life isn't like that. So empirical
link |
01:45:39.280
reality does not have this imagery in any obvious way. And yet the laws did.
link |
01:45:44.720
It's almost like the laws of physics are missing something fundamental about life
link |
01:45:48.640
if it holds that property, right? Well, that's the embarrassing nature of it.
link |
01:45:53.760
Yeah, it's embarrassing. Well, people worked hard at what this was a problem that's thought to
link |
01:46:03.200
belong to the foundations of statistical mechanics or the foundations of thermodynamics
link |
01:46:10.400
to understand how behavior, which is grossly not symmetric with respect to reversing the
link |
01:46:19.920
direction of time in large objects, how that can emerge from equations which are symmetric
link |
01:46:26.320
with respect to changing the direction of time to a very good approximation. And that's still
link |
01:46:31.920
an interesting endeavor that's interesting. And actually, it's an exciting frontier of physics
link |
01:46:38.240
now to sort of explore the boundary between when that's true and when it's not true, when you get
link |
01:46:42.560
to smaller objects and exceptions like time crystals. I definitely have to ask you about
link |
01:46:48.720
time crystals in a second here. So the CP problem and T, so there's lost all of these.
link |
01:46:55.520
We're in danger of infinite regress, but we'll have to convert soon.
link |
01:46:58.880
No, it can't possibly be turtles all the way down. We're going to get to the bottom turtle.
link |
01:47:03.280
Okay. So it got to be a really puzzling thing why the laws should have this very odd property
link |
01:47:15.200
that we don't need. And in fact, it's kind of an embarrassment in addressing empirical reality.
link |
01:47:22.000
But it seemed to be almost, it seemed to be exactly true for a long time. And then almost true.
link |
01:47:30.880
And in way almost true is even is more disturbing than exactly true because
link |
01:47:36.480
exactly true. It could have been just a fundamental feature of the world. And at some
link |
01:47:40.400
level, you just have to take it as it is. And if it's a beautiful, easily articulatable
link |
01:47:45.920
regularity, you could say that, okay, that's fine as a fundamental law of nature. But to say that
link |
01:47:52.160
is approximately true, but not exactly. That's not weird. That's weird. So, and then, so there was
link |
01:47:59.360
great progress in the late part of the 20th century in getting to an understanding of
link |
01:48:09.360
fundamental interactions in general, that shed light on this issue. It turns out that the
link |
01:48:18.000
basic principles of relativity and quantum mechanics plus the kind of high degree of
link |
01:48:25.680
symmetry that we found, the so called gauge symmetry that characterizes the fundamental
link |
01:48:31.200
interactions. When you put all that together, it's a very, very constraining framework.
link |
01:48:36.160
And it has some indirect consequences because the possible interactions are so constrained.
link |
01:48:45.840
And one of the indirect consequences is that the possibilities for violating the symmetry
link |
01:48:54.240
between forwards and backwards in time are very limited. They're basically only two.
link |
01:48:59.040
Okay. And one of them occurs and leads to a very rich theory that explains the Cronin fish
link |
01:49:06.720
experiment. And a lot of things that have been done subsequently has been used to make all kinds
link |
01:49:11.600
of successful predictions. So, that's turned out to be a very rich interaction. It's esoteric,
link |
01:49:20.560
and the effects are only show up at accelerators and are small and so on. But they might have
link |
01:49:24.720
been very important in the early universe and lead to them be connected to the asymmetry between
link |
01:49:30.000
matter and antimatter in the present universe. But that's another digression. The point is that
link |
01:49:39.200
that was fine. That was a triumph to say that there was one possible kind of interaction that
link |
01:49:44.960
would violate time reversal symmetry. And sure enough, there it is. But the other kind doesn't
link |
01:49:53.280
occur. So, we still got a problem. Why doesn't it occur? So, we're close to really finally
link |
01:50:01.280
understanding this profound gratuitous feature of the world that is almost but not quite symmetric
link |
01:50:08.240
under reversing the direction of time, but not quite there. And to get to understand that last bit
link |
01:50:16.800
is a challenging frontier of physics today. And we have a promising proposal for how it works,
link |
01:50:27.360
which is a kind of theory of evolution. So, there's this possible interaction, which we call a
link |
01:50:36.080
coupling, and there's a numerical quantity that tells us how strong that is. And traditionally
link |
01:50:42.880
in physics, we think of these kinds of numerical quantities as constants of nature that you just
link |
01:50:51.840
have to put them in from experiment. They have a certain value and that's it. And who am I to
link |
01:50:59.520
question? They seem to be just constants. But in this case, it's been fruitful to think and work
link |
01:51:13.840
out a theory where that strength of interaction is actually not a constant. It's a field or the
link |
01:51:30.160
fundamental ingredients of modern physics. There's an electron field, there's a photon field,
link |
01:51:35.040
which is also called the electromagnetic field. And so, all of these particles are manifestations
link |
01:51:40.080
of different fields. And there could be a field, something that depends on space and time,
link |
01:51:47.520
so a dynamical entity instead of just a constant here. And if you do things in a nice way,
link |
01:51:57.440
that's very symmetric, very much suggested aesthetically by the theory, but the theory
link |
01:52:03.920
we do have, then you find that you get a field which as it evolves from the early universe
link |
01:52:17.200
settles down to a value that's just right to make the laws very nearly exact,
link |
01:52:29.040
invariant or symmetric with respect to reversal of time.
link |
01:52:33.440
It might appear as a constant, but it's actually a field that evolved over time.
link |
01:52:36.480
It evolved over time. But when you examine this proposal in detail, you find that it hasn't quite
link |
01:52:44.720
settled down to exactly zero. The field is still moving around a little bit. And because the motion
link |
01:52:53.760
is so, the motion is so difficult. The material is so rigid. And this
link |
01:53:00.960
mistero, the field that fills all space is so rigid. Even small amounts of motion can involve
link |
01:53:06.000
lots of energy. And that energy takes the form of particles, fields that are in motion are always
link |
01:53:17.040
associated with particles. And those are the axions. And if you calculate how much energy is in these
link |
01:53:23.920
residual oscillations, this axion gas that fills all the universe, if this fundamental theory
link |
01:53:31.200
is correct, you get just the right amount to make the dark matter that astronomers want.
link |
01:53:39.200
And it has just the right properties. So I'd love to believe that.
link |
01:53:44.080
So that might be a thing that unlocks might be the key to understanding dark matter.
link |
01:53:50.000
Yeah, I'd like to think so. And many, many physicists are coming around to this point of
link |
01:53:53.840
view, which I've been a voice in the wilderness. I was a voice in the wilderness so long time.
link |
01:54:00.640
But now, now it's become very popular, maybe even dominant.
link |
01:54:04.480
So almost like, so this axion particle slash field would be the thing that explains dark matter.
link |
01:54:13.840
It would solve this fundamental question of finally of why the laws are almost but not
link |
01:54:21.600
quite exactly the same if you run them backwards in time. And then seemingly in a totally different
link |
01:54:30.240
conceptual universe, it would also provide, give us an understanding of the dark matter.
link |
01:54:37.840
That's not what it was designed for. And the theory wasn't, wasn't proposed with that in mind.
link |
01:54:45.040
But when you work out the equations, that's what you get.
link |
01:54:47.760
That's always a good sign. Yes.
link |
01:54:50.880
I think I vaguely read somewhere that there may be early experimental validation of axion.
link |
01:54:59.520
Is that am I, am I reading the wrong?
link |
01:55:02.000
Well, there have been quite a few false alarms and I think there are some of them still,
link |
01:55:08.000
people desperately want to find this thing. But I don't think, I don't think any of them
link |
01:55:14.400
are convincing at this point, but there are very ambitious experiments and kind of new,
link |
01:55:22.880
you have to design new kinds of antennas that are capable of detecting these predicted particles.
link |
01:55:28.160
And it's very difficult. They interact very, very weakly. If it were easy, it would have been
link |
01:55:32.800
done already. But I think there's good hope that we can get down to the required sensitivity
link |
01:55:40.880
and actually test whether these ideas are right in coming years or maybe decades.
link |
01:55:47.840
And then understand one of the big mysteries, like literally big in terms of
link |
01:55:52.800
its fraction of the universe is dark matter. Yes.
link |
01:55:55.600
Yes. Let me ask you about, you mentioned a few times, time crystals.
link |
01:56:01.840
What are they? These things are, it's a very beautiful idea when we started to treat space and
link |
01:56:08.160
time as similar frameworks, physical phenomena. Right. That's what motivated it.
link |
01:56:17.440
First of all, what are crystals and what are time crystals?
link |
01:56:20.400
Okay. So crystals are orderly arrangements of atoms in space. And many materials, if you cool them
link |
01:56:32.080
down gently, will form crystals. And so we say that that's a state of matter that forms spontaneously.
link |
01:56:45.200
And an important feature of that state of matter is that the end result, the crystal,
link |
01:56:56.880
has less symmetry than the equations that give rise to the crystal. So the equations,
link |
01:57:05.360
the basic equations of physics, are the same if you move a little bit. So you can move,
link |
01:57:13.520
they're homogeneous, but crystals aren't. The atoms are in particular places that they have
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01:57:19.200
less symmetry. And time crystals are the same thing in time. But of course, it's not, so it's
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not positions of atoms, but it's ordering orderly behavior that certain states of matter will
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arrange themselves into spontaneously if you treat them gently and let them do what they want to do.
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But repeat in that same way indefinitely.
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That's the crystal inform. You can also have time liquids or you can have all kinds of other
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states of matter. You don't have space time crystals where the pattern only repeats if,
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with each step of time, you also move at a certain direction in space.
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So basically, it's states of matter that display structure in time spontaneously.
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So here's the difference. When it happens in time, it sure looks a lot like it's motion.
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And if it repeats indefinitely, it sure looks a lot like perpetual motion.
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Yeah. It looks like free lunch. I was told that there's no such thing as free lunch.
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Does this violate laws of thermodynamics?
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No, but it requires a critical examination of the laws of thermodynamics. Let me say on
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background that the laws of thermodynamics are not fundamental laws of physics. There are things we
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prove under certain circumstances emerge from the fundamental laws of physics. We don't
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posit them separately. They're meant to be deduced. And they can be deduced under limited
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circumstances but not necessarily universally. And we found finding some of the subtleties and
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sort of edge cases where they don't apply in a straightforward way. And this is one.
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So time crystals do obey, do have this structure in time, but it's not a free lunch because although,
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in a sense, things are moving, they're already doing what they want to do.
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So if you want to extract energy from it, you're going to be foiled because there's no spare energy
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there. So you can add energy to it and kind of disturb it, but you can't extract energy
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from this motion because it wants to do, that's the lowest energy configuration that there is,
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so you can't get further energy out of it. So in theory, I guess perpetual motion,
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you would be able to extract energy from it. If such a thing was to be created,
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you can then milk it for energy.
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Well, what's usually meant in the literature of perpetual motion is
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a kind of macroscopic motion that you could extract energy from and somehow it would crank
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back up. That's not the case here. If you want to extract energy, this motion is not something
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you're going to extract energy from. If you intervene in the behavior, you can change it,
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but only by injecting energy, not by taking away energy.
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02:00:50.960
You mentioned that a theory of everything may be quite difficult to come by. A theory of everything
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broadly defined meaning truly a theory of everything. But let's look at a more narrow
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theory of everything, which is that the way it's used often in physics is a theory that unifies
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our current laws of physics, general relativity, quantum field theory. Do you have thoughts on
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this dream of a theory of everything in physics? How close are we? Is there any promising ideas
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out there in your view? Well, it would be nice to have. It would be aesthetically pleasing.
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Will it be useful? No, probably not. Well, I shouldn't. It's dangerous to say that,
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but probably not. I think we're certainly not in the foreseeable future.
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Maybe to understand black holes. Yes, maybe to understand black holes, but
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that's not useful. It's not useful in the sense that we're not going to be basing any technology
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anytime soon on black holes, but it's more severe than that, I would say. It's that
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that the kinds of questions about black holes that we can't answer within the framework of
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existing theory are ones that are not going to be susceptible to astronomical observation
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in the foreseeable future. There are questions about very, very small black holes when quantum
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effects come into play or so that black holes are not black holes. They're emitting this
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discovery of Hawking called Hawking radiation, which for astronomical black holes is a tiny,
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tiny effect that no one has ever observed. It's a prediction that's never been checked.
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I feel like supermassive black holes that doesn't apply.
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No, no. The predicted rate of radiation from those black holes is so tiny that it's absolutely
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unobservable and is overwhelmed by all kinds of other effects. It's not practical in the sense
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of technology. It's not even practical in the sense of application to astronomy. We are existing
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theory of general relativity and quantum theory and our theory of the different fundamental
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forces is perfectly adequate to all problems of technology, for sure, and almost all problems
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of astrophysics and cosmology that appear except with the notable exception of the extremely
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early universe, if you want to ask what happened before the Big Bang or what happened right at the
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Big Bang, which would be a great thing to understand, of course. We don't.
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But what about the engineering question? So if we look at space travel, I think you've spoken
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with him, Eric Weinstein, really he says things like we want to get off this planet. His intuition
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is almost a motivator for the engineering project of space exploration. In order for us to crack
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this problem of becoming a multiplanetary species, we have to solve the physics problem. His intuition
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is like if we figure out what he calls the source code, which is like a theory of everything might
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give us clues on how to start hacking the fabric of reality, like getting shortcuts, right?
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It might. I can't say that it won't, but I can say that in the 1970s and early 1980s,
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we achieved huge steps in understanding matter. QCD, much better understanding of the weak
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interaction, much better understanding of quantum mechanics in general, and it's had minimal impact
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on technology. On rocket design, on propulsion. Certainly on rocket design, on anything, any
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technology whatsoever. Now we're talking about much more esoteric things. Since I don't know
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what they are, I can't say for sure that they won't affect technology, but I'm very, very skeptical
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that they would affect technology. Because to access them, you need very exotic circumstances
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to make new kinds of particles with high energy. You need accelerators that are very expensive
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and you don't produce many of them and so forth. It's a pipe dream, I think, about space exploration.
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I'm not sure exactly what he has in mind, but to me, it's more a problem of something between
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biology and information processing. What you mean, I think human bodies are not well adapted
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to space. Even Mars, which is the closest thing to a kind of human environment that we're going
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to find anywhere close by, very, very difficult to maintain humans on Mars and very expensive
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and very unstable. However, if we take a broader view of what it means to bring human civilization
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outside of the Earth, if we're satisfied with sending minds out there that we can
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converse with and actuators that we can manipulate and sensors that we can get feedback from,
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I think that's where it's at. I think that's so much more realistic. I think that's
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the long term future of space exploration. It's not hauling human bodies all over the place and
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that's just silly. It's possible that human bodies, like you said, it's a biology problem.
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What's possible is that we extend human lab span in some way. We have to look at a bigger picture.
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It could be just like you're saying by sending robots with actuators and extending our limbs,
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but it could also be extending some aspect of our minds and information.
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It could be cyborgs. It could be human brains or cells that realize something like human brain
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architecture within artificial environments, shells, if you like, that are more adapted
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to the conditions of space. Man machine hybrids as well as remote outposts that we can communicate
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with. I think those will happen. To me, there's some sense in which, as opposed to understanding
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the physics of the fundamental fabric of the universe, I think getting to the physics of
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life, the physics of intelligence, the physics of consciousness, the physics of information
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that brings from which life emerges, that will allow us to do space exploration.
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02:09:32.560
Well, I think physics in the larger sense has a lot to contribute here,
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not the physics of finding fundamental new laws in the sense of another quark or axions even.
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Physics has a lot of experience in analyzing complex situations and analyzing new states
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of matter and devising new kinds of instruments that do clever things. Physics in that sense
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has enormous amounts to contribute to this kind of endeavor, but I don't think that looking for a
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so called theory of everything has much to do with it at all.
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02:10:18.880
What advice would you give to a young person today with a bit of fire in their eyes,
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high school student, college student thinking about what to do with their life,
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maybe advice about career or bigger advice about life in general?
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02:10:37.280
Well, first read fundamentals because there I've tried to give some coherent,
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deep advice. That's fundamentals, 10 keys to reality by Frank Ulczak.
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02:10:50.000
So that's a good place to start.
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02:10:50.880
Available everywhere.
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If you want to learn what I can tell you.
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Is there an audiobook? Yes, there is an audiobook, that's awesome.
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02:11:00.480
Yeah, I think I can give three pieces of wise advice that I think are generally applicable.
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One is to cast a wide net, to really look around and see what looks promising,
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what catches your imagination. You have to balance those two things.
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You can have things that catch your imagination, but don't look promising in the sense that
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the questions aren't ripe. And things that you, in part of what makes things
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attractive is that, whether you thought you liked them or not, if you can see that there's
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ferment and new ideas coming up, that's attractive in itself. So when I started out,
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I thought I was, and when I was an undergraduate, I intended to study philosophy or questions of
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how mind emerges from matter, but I thought that that wasn't really ripe.
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The timing isn't right yet.
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The timing wasn't right for the kind of mathematical thinking and
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conceptualization that I really enjoy and am good at.
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But so that's one thing, cast a wide net, look around. And that's
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a pretty easy thing to do today because of the internet. You can look at all kinds of things.
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You have to be careful, though, because there's a lot of crap also. But you can sort of tell the
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difference if you do a little digging. So don't settle on just what your thesis advisor tells
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you to do or what your teacher tells you to do. Look for yourself and get a sense of what seems
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promising, not what seemed promising 10 years ago. So that's one. Another thing is kind of
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complimentary to that. Well, they're all complimentary. Complimentary to that is to
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read history and read the masters of the history of ideas and masters of ideas.
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02:13:22.160
I benefited enormously as early in my career from reading in physics, Einstein in the original,
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and Feynman's lectures as they were coming out, and Darwin. You can learn what it is in Galileo.
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You can learn what it is to wrestle with difficult ideas and how great minds did that.
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You can learn a lot about style, how to write your ideas up and express them in clear ways.
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And also just a couple of that with, I also enjoy reading biographies.
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And biographies, yes, similarly. So it gives you the context of the human being that created
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those ideas. Right. And brings it down to earth in the sense that it was really human beings who
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did this, and they made mistakes. And I also got inspiration from Bertrand Russell, who was a big
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hero, and H.G. Wells. So read the masters, make contact with great minds. And when you are sort
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of narrowing down on a subject, learn about the history of the subject, because that really puts
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in context what you're trying to do, and also gives a sense of community and grandeur to the whole
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enterprise. And then the third piece of advice is complementary to both those, which is sort of to
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get the basics under control as soon as possible. So if you want to do theoretical work in science,
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you know, you have to learn calculus, multivariable calculus, complex variables, group theory.
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02:15:10.800
Nowadays, you have to be highly computer literate. If you want to do experimental work, you also have
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to be computer literate, then you have to learn about electronics and optics and instruments.
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02:15:21.440
And so get that under control as soon as possible, because it's like learning a language
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to produce great works and express yourself fluently and with confidence.
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It should be your native language. These things should be like your native language,
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02:15:41.200
so you're not wondering what is a derivative. This is just part of your, you know, it's in your
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bones, so to speak. And the sooner that you can do that, the better. So all those things
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can be done in parallel and should be. You've accomplished some incredible things in your life,
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but the sad thing about this thing we have is it ends. Do you think about your mortality?
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Are you afraid of death? Well, afraid is the wrong word. I mean,
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I wish it weren't going to happen, and I'd like to. But do you think about it?
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02:16:28.720
Occasionally, I think about, well, I think about it very operationally in the sense that
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there's always a tradeoff between exploration and exploitation. This is a classic subject in
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computer science, actually, in machine learning, that when you're in an unusual circumstance,
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so you want to explore to see what the landscape is and gather data. But then at some point,
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you want to use that, make choices and say, this is what I'm going to do and exploit the
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knowledge you've accumulated. And the longer the period of exploitation you anticipate,
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02:17:10.320
the more exploration you should do in new directions. And so for me, I've had to sort of
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adjust the balance of exploration and exploitation. And that said, you've explored quite a lot.
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Yeah. Well, I haven't shut off the exploitation at all. I'm still hoping for the exploration.
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Right. I'm still hoping for 10 or 15 years of top flight performance. But
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the several years ago now, when I was 50 years old, I was at the Institute for Advanced Study and
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my office was right under Freeman Dyson's office and we were kind of friendly. And
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he found out it was my 50th birthday and said, congratulations. And you should feel liberated
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02:18:02.880
because no one expects much of a 50 year old theoretical physicist. And he obviously had felt
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liberated by reaching a certain age. And yeah, there is something to that. I feel I don't have
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to catch, I don't have to keep in touch with the latest hyper technical developments in particle
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physics or string theory. Because I'm really not going to be exploiting that. But where I am
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exploring in these directions of machine learning and things like that. But I'm also
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concentrating within physics on exploiting directions that I've already established and the
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laws that we already have. And doing things like I'm very actively involved in trying to design,
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helping people, experimentalists and engineers even to design antennas that are capable of
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02:19:06.080
detecting axions. So there, and that's there, we're deep in the exploitation stage. It's not a
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matter of finding the new laws, but of really using the laws we have to kind of finish the
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story off. So it's complicated. But I'm very happy with my life right now and I'm enjoying it. And
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I don't want to cloud that by thinking too much that it's going to come to an end.
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02:19:36.800
And you know, it's a gift I didn't earn. Is there a good thing to say about why this gift
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that you've gotten and didn't deserve is so damn enjoyable? So like, what's the meaning of this
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thing of life? To me, interacting with people I love, my family, and I have a very wide circle
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of friends now. And I'm trying to produce some institutions that will survive me as well as
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02:20:11.280
work. And it's just, it's, how should I say, it's a positive feedback work loop when you do
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02:20:23.920
something and your people appreciate it. And then you want to do more and they get rewarded.
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02:20:29.440
And it's just, how should I say, this is another gift that I didn't earn and don't
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02:20:34.320
understand, but I have a dopamine system. And yeah, I'm happy to use it.
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02:20:42.080
It seems to get energized by the creative process, by the process of exploration.
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02:20:48.800
Very much so.
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02:20:49.520
And all of that started from the little fluctuations shortly after the Big Bang.
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02:20:57.680
Frank, well, whatever the, those initial conditions and fluctuation did that created you,
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02:21:03.440
I'm glad they did. This was, thank you for all the work you've done for the many people you've
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inspired, for the many of the billion, most of your ideas were pretty useless of the
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several billions, but as it is for all humans, but you had quite a few truly special ideas.
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02:21:21.680
And thank you for bringing those to the world. And thank you for wasting your valuable time
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02:21:25.520
with me today. It's truly not.
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02:21:27.760
It's been a joy. And I hope people enjoy it. And I think, you know, the kind of mind expansion
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02:21:35.600
that I've enjoyed by interacting with physical reality at this deep level, I think can be
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02:21:42.080
conveyed to and enjoyed by many, many people. And that's, that's one of my missions in life.
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02:21:47.440
It's beautiful.
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02:21:49.200
Thanks for listening to this conversation with Frank Wilczak. And thank you to
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02:21:52.640
the information, Natsuit, ExpressVPN, Blinkist, and Aidsleep. Check them out in the description
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02:21:59.680
to support this podcast. And now let me leave you with some words from Albert Einstein.
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02:22:04.320
Nothing happens until something moves. Thanks for listening and hope to see you next time.