back to indexFrank 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,
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a theoretical physicist at MIT who won the Nobel Prize
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for the co discovery of asymptotic freedom
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in the theory of strong interaction.
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Quick mention of our sponsors,
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the Information, NetSuite, ExpressVPN, Blinkist,
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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.
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Protons and neutrons make up the nucleus of an atom.
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Strong interaction is responsible
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for the strong nuclear force that binds them.
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But strong interaction also holds together the quarks
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that make up the protons and neutrons.
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Frank Wilczek, David Gross, and David Politzer
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came up with a theory postulating
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that when quarks come really close to one another,
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the attraction abates and they behave like free particles.
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This is called asymptotic freedom.
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This happens at very, very high energies,
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which is also where all the fun is.
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This is the Lex Friedman Podcast,
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and here is my conversation with Frank Wilczek.
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What is the most beautiful idea in physics?
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The most beautiful idea in physics
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is that we can get a compact description of the world
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that's very precise and very full
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at the level of the operating system of the world.
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That's an extraordinary gift.
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And we get worried when we find discrepancies
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between our description of the world
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and what's actually observed
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at the level even of a part in a billion.
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You actually have this quote from Einstein
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that the most incomprehensible thing
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about the universe is that it is comprehensible,
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something like that.
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Yes, so that's the most beautiful surprise
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that I think that really was to me the most profound result
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of the scientific revolution of the 17th century
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with the shining example of Newtonian physics
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that you could aspire to completeness, precision,
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and a concise description of the world,
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of the operating system.
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And it's gotten better and better over the years
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and that's the continuing miracle.
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Now, there are a lot of beautiful sub miracles too.
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The form of the equations is governed
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by high degrees of symmetry
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and they have a very surprising kind
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of mind expanding structure,
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especially in quantum mechanics.
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But if I had to say the single most beautiful revelation
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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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We can do, you can point to things like
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the rise of gross national products per capita
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around the world as a result of the scientific revolution.
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You can see it all around you.
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And recent developments with exponential production
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of wealth, control of nature at a very profound level
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where we do things like sense tiny, tiny, tiny, tiny
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vibrations to tell that there are black holes
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colliding far away or we test laws as I alluded to
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whether it's part in a billion and do things
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in what appear on the surface
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to be entirely different conceptual universes.
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I mean, on the one hand, pencil and paper
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are nowadays computers that calculate abstractions
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and on the other hand, magnets and accelerators
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and detectors that look at the behavior
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of fundamental particles and these different universes
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have to agree or else we get very upset
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and that's an amazing thing if you think about it.
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And it's telling us that we do understand a lot
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about nature at a very profound level
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and there are still things we don't understand of course
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but as we get better and better answers
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and better and better ability to address difficult questions
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we can ask more and more ambitious questions.
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Well, I guess the hope part of that is because
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we are surrounded by mystery.
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So one way to say it, if you look at the growth GDP
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over time that we figured out quite a lot
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and we're able to improve the quality of life
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because of that and we've figured out some fundamental things
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about this universe but we still don't know
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how much mystery there is and it's also possible
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that there's some things that are in fact incomprehensible
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to both our minds and the tools of science.
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Like the sad thing is we may not know it
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because in fact they are incomprehensible
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and that's the open question is how much
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of the universe is comprehensible?
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If we figured out everything what's inside the black hole
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and everything that happened at the moment of the Big Bang
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does that still give us the key
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to understanding the human mind
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and the emergence of all the beautiful complexity
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That's not like when I see these objects
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like I don't know if you've seen them like cellular automata
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all these kinds of objects where the from simple rules
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emerges complexity, it makes you wonder maybe
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it's not reducible to simple beautiful equations
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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
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we have to kind of draw careful distinctions
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about or definitions about what we mean by that.
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Both the universe and the kind of and the comprehensive.
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Exactly, right so the so in certain areas
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of understanding reality we've made extraordinary progress
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I would say in understanding fundamental physical processes
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and getting very precise equations that really work
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and allow us to do the profound sculpting of matter
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to make computers and iPhones and everything else
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and they really work and they're extraordinary productions
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on the other but and that's all based
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on the laws of quantum mechanics
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and they really work and they give us tremendous control
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of nature on the other hand as we get better answers
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we can also ask more ambitious questions
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and there are certainly things that have been observed
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even in what would be usually called the realm of physics
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that aren't understood for instance there seems to be
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another source of mass in the universe
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the so called dark matter that we don't know what it is
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and it's a very interesting question what it is then
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but also as you were alluding to there's it's one thing
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to know the basic equations it's another thing
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to be able to solve them in important cases
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so we run up against the limits of that
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in things like chemistry where we'd like to be able
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to design molecules and predict their behavior
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from the equations we think the equations could do that
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in principle but in practice it's very challenging
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to solve them in all but very simple cases
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and then there's the other thing which is that a lot
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of what we're interested in is historically conditioned
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it's not a matter of the fundamental equations
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but about what has evolved or come out
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of the early universe and formed into people and frogs
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and societies and things and the laws of physics
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the basic laws of physics only take you so far
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in that it kind of provides a foundation
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but doesn't really that you need entirely different concepts
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to deal with those kind of systems
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and one thing I can say about that is that the laws
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themselves point out their limitations
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that they kind of their laws for dynamical evolution
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so they tell you what happens if you have
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a certain starting point but they don't tell you
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what the starting point should be at least yeah
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and the other thing that emerges
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from the equations themselves is the phenomena
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of chaos and sensitivity to initial conditions
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which tells us that you have that there are intrinsic
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limitations on how well we can spell out the consequences
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of the laws if we try to apply them.
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It's the old apple pie if you want to what is it
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make an apple pie from scratch you have to build
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the universe or something like that.
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Well you're much better off starting with apples
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than starting with quarks let's put it that way.
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In your book A Beautiful Question you ask
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does the world embody beautiful ideas?
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So the book is centered around this very interesting
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question it's like Shakespeare you can like dig in
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and read into all the different interpretations
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of this question but at the high level what to use
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the connection between beauty of the world
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and physics of the world.
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In a sense we now have a lot of insight into what
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the laws are the form they take that allow us
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to understand matter in great depth and control it
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as we've discussed and it's an extraordinary thing
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how mathematically ideal those equations turn out to be.
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In the early days of Greek philosophy Plato had this model
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of atoms built out of the five perfectly symmetrical
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platonic solids so there was somehow the idea
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that mathematical symmetry should govern the world
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and we've out Platoed Plato by far in modern physics
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because we have symmetries that are much more extensive
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much more powerful that turn out to be the ingredients
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out of which we construct our theory of the world
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and it works and so that's certainly beautiful.
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So the idea of symmetry which is a driving inspiration
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in much of human art especially decorative art
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like the Alhambra or wallpaper designs or things
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you see around you everywhere also turns out to be
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the dominant theme in modern fundamental physics
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symmetry and its manifestations the laws turn out
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to be very to have these tremendous amounts of symmetry
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you can change the symbols and move them around
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in different ways and they still have the same consequences.
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So that's beautiful that these concepts that humans
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find appealing also turn out to be the concepts
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that govern how the world actually works.
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I don't think that's an accident.
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I think humans were evolved to be able to interact
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with the world in ways that are advantageous
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and to learn from it and so we are naturally evolved
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or designed to enjoy beauty and it's a symmetry
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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
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emerge at many levels of the hierarchy of the universe.
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So you're talking about particles but it also is
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at the level of chemistry and biology
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and the fact that our cognitive sort of our perception
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system and whatever our cognition is also finds
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it appealing or somehow our sense of what is beautiful
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is grounded in this idea of symmetry
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or the breaking of symmetry.
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Symmetry is at the core of our conception of beauty
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whether it's the breaking or the non breaking
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It makes you wonder why.
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So I come from Russia and the question of Dostoevsky
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he has said that beauty will save the world.
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Maybe as a physicist you can tell me
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what do you think he meant by that?
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I don't know if it saves the world
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but it does turn out to be a tremendous source
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of insight into the world.
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When we investigate kind of the most fundamental
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interactions, things that are hard to access
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because they occur at very short distances
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between very special kinds of particles
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whose properties are only revealed at high energies.
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We don't have much to go on from everyday life
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but so we have when we guess what the,
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and the experiments are difficult to do
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so you can't really follow a very wholly empirical procedure
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to sort of in the Baconian style figure out the laws
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kind of step by step just by accumulating a lot of data
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what we actually do is guess.
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And the guesses are kind of aesthetic really.
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What would be a nice description
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that's consistent with what we know
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and then you try it out and see if it works
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and by gosh it does in many profound cases.
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So there's that but there's another source of symmetry
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which I didn't talk so much about in a beautiful question
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but does relate to your comments
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and I think very much relates to the source of symmetry
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that we find in biology and in our heads, you know,
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in our brain which is that, well it is discussed a bit
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in a beautiful question and also in fundamentals
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is that when you have, symmetry is also a very important
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means of construction.
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So when you have for instance simple viruses
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that need to construct their coat, their protein coat,
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the coats often take the form of platonic solids
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and the reason is that the viruses are really dumb
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and they only know how to do one thing
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so they make a pentagon then they make another pentagon
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and they make another pentagon
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and they all glue together in the same way
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and that makes a very symmetrical object sort of.
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So the rules of development when you have simple rules
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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
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for generating fractals, like the kind of broccoli
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that has all this internal structure
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and I wish I had a picture to show
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but maybe people remember it from the supermarket
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and you say how did a vegetable get so intelligent
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to make such a beautiful object
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with all this fractal structure
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and the secret is stupidity.
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You just do the same thing over and over again
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and in our brains also, you know, we came out,
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we start from single cells and they reproduce
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and each one does basically roughly the same thing.
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The program evolves in time, of course,
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different modules get turned on and off,
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different regions of the genetic code
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get turned on and off but basically,
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a lot of the same things are going on
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and they're simple things
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and so you produce the same patterns over and over again
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and that's a recipe for producing symmetry
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because you're getting the same thing in many, many places
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and if you look at, for instance,
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the beautiful drawings of Roman Icahal,
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the great neuroanatomist who drew the structure
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of different organs like the hippocampus,
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you see it's very regular and very intricate
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and it's symmetry in that sense
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because it's many repeated units
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that you can take from one place to the other
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and see that they look more or less the same.
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But what you're describing, this kind of beauty
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that we're talking about now is a very small sample
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in terms of space time in a very big world
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in a very short, brief moment in this long history.
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In your book, Fundamentals, 10 Keys to Reality,
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I'd really recommend people read it.
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You say that space and time are pretty big or very big.
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How big are we talking about?
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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
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involved, of course, but one thing I'd like to say
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is that if you take a broad enough view,
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the history of the universe is simpler
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than the history of Sweden, say,
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because your standards are lower.
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But just to make it quantitative,
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I'll just give a few highlights.
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And it's a little bit easier to talk about time,
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so let's start with that.
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The Big Bang occurred, we think.
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The universe was much hotter and denser and more uniform
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about 13.8 billion years ago,
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and that's what we call the Big Bang.
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And it's been expanding and cooling,
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the matter in it has been expanding and cooling ever since.
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So in a real sense, the universe is 13.8 billion years old.
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That's a big number, kind of hard to think about.
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A nice way to think about it, though,
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is to map it onto one year.
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So let's say the universe just linearly mapped
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the time intervals from 13.8 billion years onto one year.
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So the Big Bang then is on January 1st at 12 a.m.
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And you wait for quite a long time
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before the dinosaurs emerge.
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The dinosaurs emerge on Christmas, it turns out.
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12 months, almost 12 months later.
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Getting close to the end, yes.
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Getting close to the end.
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And the extinction event that let the mammals
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and ultimately humans inherit the Earth
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from the dinosaurs occurred on December 30th.
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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,
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and a human lifetime is a very, very infinitesimal part
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of this interval of these gigantic cosmic reaches of time.
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And in space, we can tell a very similar story.
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In fact, it's convenient to think that the size
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of the universe is the distance that light can travel
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in 13.8 billion years.
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So it's 13.8 billion light years.
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That's how far you can see out.
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That's how far signals can reach us.
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And that is a big distance.
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That is a big distance because compared to that, the Earth
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is a fraction of a light second.
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So again, it's really, really big.
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And so if we wanna think about the universe
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as a whole in space and time,
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we really need a different kind of imagination.
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It's not something you can grasp
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in terms of psychological time in a useful way.
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You have to think, you have to use exponential notation
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and abstract concepts to really get any hold
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on these vast times and spaces.
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On the other hand, let me hasten to add
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that that doesn't make us small
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or make the time that we have to us small.
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Because again, looking at those pictures
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of what our minds are and some of the components
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of our minds, these beautiful drawings
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of the cellular patterns inside the brain,
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you see that there are many, many, many processing units.
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And if you analyze how fast they operate,
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I tried to estimate how many thoughts
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a person can have in a lifetime.
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That's kind of a fuzzy question,
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but I'm very proud that I was able
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to define it pretty precisely.
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And it turns out we have time for billions
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of meaningful thoughts in a lifetime.
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We shouldn't think of ourselves as terribly small
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either in space or in time,
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because although we're small in those dimensions
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compared to the universe, we're large compared
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to meaningful units of processing information
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and being able to conceptualize and understand things.
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Yeah, but 99% of those thoughts are probably food,
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sex, or internet related.
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Well, yeah, well, they're not necessarily, that's right.
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Only like point one is Nobel Prize winning ideas.
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That's true, but there's more to life
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than winning Nobel Prizes.
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How did you do that calculate?
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Can you maybe break that apart a little bit,
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just kind of for fun, sort of an intuition
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of how we calculate the number of thoughts?
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The number of thoughts, right.
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It's necessarily imprecise because a lot of things
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are going on in different ways and what is a thought.
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But there are several things that point
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to more or less the same rate of being able
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to have meaningful thoughts.
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For instance, the one that I think is maybe
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the most penetrating is how fast
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we can process visual images.
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How do we do that?
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If you've ever watched old movies,
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you can see that, well, any movie, in fact,
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a motion picture is really not a motion picture.
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It's a series of snapshots that are playing
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one after the other and it's because our brains
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also work that way.
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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,
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create the illusion of continuity and flow,
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we can deal with that.
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And if the flicker rate is too slow,
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then you start to see that it's a series of snapshots
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and you can ask, what is the crossover?
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When does it change from being something
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that is matched to our processing speed versus too fast?
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And it turns out about 40 per second.
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And then if you take 40 per second as how well,
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how fast we can process visual images,
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you get to several billions of thoughts.
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If you, similarly, if you ask what are some
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of the fastest things that people can do?
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Well, they can play video games,
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they can play the piano very fast if they're skilled at it.
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And again, you get to similar units
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or how fast can people talk?
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You get to similar, you know,
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within a couple of orders of magnitude,
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you get more or less to the same idea.
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So that's how you can say that there's billions
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of meaningful, there's room for billions
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of meaningful thoughts.
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I won't argue for exactly two billion versus 1.8 billion.
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It's not that kind of question,
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but I think any estimate that's reasonable
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will come out within, say, 100 billion and 100 million.
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It would be interesting to map out
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for an individual human being the landscape of thoughts
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that they've sort of traveled.
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If you think of thoughts as a set of trajectories,
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what that landscape looks like.
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I mean, I've been recently really thinking
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about this Richard Dawkins idea of memes
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and just all this ideas and the evolution of ideas
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inside of one particular human mind
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and how they're then changed and evolved
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by interaction with other human beings.
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It's interesting to think about.
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So if you think the number is billions,
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you think there's also social interaction.
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So these aren't like there's interaction
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in the same way you have interaction with particles.
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There's interaction between human thoughts
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that perhaps that interaction in itself
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is fundamental to the process of thinking.
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Like without social interaction,
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we would be like stuck, like walking in a circle.
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We need the perturbation of other humans
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to create change and evolution.
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Once you bring in concepts of interactions
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and correlations and relations,
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then you have what's called a combinatorial explosion
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that the number of possibilities expands exponentially
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technically with the number of things you're considering.
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And it can easily rapidly outstrip these billions
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of thoughts that we're talking about.
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So we definitely cannot by brute force
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master complex situations
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or think of all the possibilities in a complex situations.
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I mean, even something as relatively simple as chess
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is still something that human beings
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can't comprehend completely.
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Even the best players lose, still sometimes lose
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and they consistently lose to computers these days.
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And in computer science, there's a concept of NP complete.
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So large classes of problems when you scale them up
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beyond a few individuals become intractable.
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And so that in that sense, the world is inexhaustible.
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And that makes it beautiful that we can make any laws
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that generalize efficiently and well
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can compress all of that combinatorial complexity
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just like a simple rule.
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That in itself is beautiful.
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It's a happy situation.
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And I think that we can find general principles
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of sort of of the operating system
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that are comprehensible, simple, extremely powerful
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and let us control things very well
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and ask profound questions.
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And on the other hand,
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that the world is going to be inexhaustible.
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That once we start asking about relationships
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and how they evolve and social interactions
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and we'll never have a theory of everything
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in any meaningful sense because that.
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Of everything, everything, truly everything is.
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Can I ask you about the Big Bang?
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So we talked about the space and time are really big.
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But then, and we humans give a lot of meaning
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to the word space and time in our like daily lives.
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But then can we talk about this moment of beginning
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and how we're supposed to think about it?
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That at the moment of the Big Bang,
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everything was what, like infinitely small
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and then it just blew up?
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We have to be careful here
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because there's a common misconception
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that the Big Bang is like the explosion of a bomb
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in empty space that fills up the surrounding place.
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As we understand it, it's the fact,
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it's the fact or the hypothesis,
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but well supported up to a point
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that everywhere in the whole universe,
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early in the history,
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matter came together into a very hot, very dense,
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if you run it backwards in time,
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matter comes together into a very hot, very dense
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and yet very homogeneous plasma
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of all the different kinds of elementary particles
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and quarks and anti quarks and gluons
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and photons and electrons and anti electrons,
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everything, all of that stuff.
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Really, really, really hot.
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We're talking about way, way hotter
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than the surface of the sun.
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Well, in fact, if you take the equations as they come,
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the prediction is that the temperature
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just goes to infinity,
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but then the equations break down.
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We don't really, there are various,
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the equations become infinity equals infinity,
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so they don't feel that it's called a singularity.
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We don't really know.
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This is running the equations backwards,
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so you can't really get a sensible idea
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of what happened before the Big Bang.
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So we need different equations
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to address the very earliest moments.
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But so things were hotter and denser.
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We don't really know why things started out that way.
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We have a lot of evidence that they did start out that way.
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But since most of the,
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we don't get to visit there and do controlled experiments.
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Most of the record is very, very processed
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and we have to use very subtle techniques
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and powerful instruments to get information
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that has survived.
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Get closer and closer to the Big Bang.
link |
Get closer and closer to the beginning of things.
link |
And what's revealed there is that, as I said,
link |
there undoubtedly was a period
link |
when everything in the universe
link |
that we have been able to look at and understand,
link |
and that's consistent with everything,
link |
is in a condition where it was much, much hotter
link |
and much, much denser,
link |
but still obeying the laws of physics
link |
as we know them today.
link |
And then you start with that.
link |
So all the matter is in equilibrium.
link |
And then with small quantum fluctuations
link |
and run it forward,
link |
and then it produces, at least in broad strokes,
link |
the universe we see around us today.
link |
Do you think we'll ever be able to,
link |
with the tools of physics, with the way science is,
link |
with the way the human mind is,
link |
we'll ever be able to get to the moment of the Big Bang
link |
in our understanding or even the moment before the Big Bang?
link |
Can we understand what happened before the Big Bang?
link |
I'm optimistic both that we'll be able to measure more,
link |
and that we'll be able to figure out more.
link |
So they're very, very tangible prospects
link |
for observing the extremely early universe,
link |
so even much earlier than we can observe now
link |
through looking at gravitational waves.
link |
Gravitational waves, since they interact so weakly
link |
with ordinary matter,
link |
sort of send a minimally processed signal from the Big Bang.
link |
It's a very weak signal
link |
because it's traveled a long way
link |
and diffused over long spaces,
link |
but people are gearing up to try to detect
link |
gravitational waves that could have come
link |
from the early universe.
link |
Yeah, LIGO's an incredible engineering project.
link |
It's the most sensitive, precise devices on Earth.
link |
The fact that humans can build something like that
link |
is truly awe inspiring from an engineering perspective.
link |
Right, but these gravitational waves from the early universe
link |
will probably be of a much longer wavelength
link |
than LIGO is capable of sensing,
link |
so there's a beautiful project
link |
that's contemplated to put lasers
link |
in different locations in the solar system.
link |
We really, really separate it
link |
by solar system scale differences,
link |
like artificial planets or moons in different places
link |
and see the tiny motions of those
link |
relative to one another
link |
as a signal of radiation from the Big Bang.
link |
We can also maybe indirectly see the imprint
link |
of gravitational waves from the early universe
link |
on the photons, the microwave background radiation.
link |
That is our present way of seeing into the earliest universe,
link |
but those photons interact much more strongly with matter.
link |
They're much more strongly processed,
link |
so they don't give us directly such an unprocessed view
link |
of the early universe, of the very early universe,
link |
but if gravitational waves leave some imprint on that
link |
as they move through, we could detect that too,
link |
and people are trying, as we speak,
link |
working very hard towards that goal.
link |
It's so exciting to think about a sensor
link |
the size of the solar system.
link |
That would be a fantastic,
link |
I mean, that would be a pinnacle artifact
link |
of human endeavor to me.
link |
It would be such an inspiring thing
link |
that just we want to know,
link |
and we go to these extraordinary lengths
link |
of making gigantic things that are also very sophisticated
link |
because what you're trying to do,
link |
you have to understand how they move.
link |
You have to understand the properties of light
link |
that are being used, the interference between light,
link |
and you have to be able to make the light with lasers
link |
and understand the quantum theory
link |
and get the timing exactly right.
link |
It's an extraordinary endeavor
link |
involving all kinds of knowledge
link |
from the very small to the very large,
link |
and all in the service of curiosity
link |
and built on a grand scale, so.
link |
Yeah, it would make me proud to be a human if we did that.
link |
I love that you're inspired both by the power of theory
link |
and the power of experiment.
link |
So both, I think, are exceptionally impressive
link |
that the human mind can come up with theories
link |
that give us a peek into how the universe works,
link |
but also construct tools that are way bigger
link |
than the evolutionary origins we came from.
link |
Right, and by the way,
link |
the fact that we can design such things and they work
link |
is an extraordinary demonstration
link |
that we really do understand a lot.
link |
And then in some ways.
link |
And it's our ability to answer questions
link |
that also leads us to be able
link |
to address more ambitious questions.
link |
So you mentioned at the Big Bang in the early days,
link |
things are pretty homogeneous.
link |
But here we are, sitting on Earth,
link |
two hairless apes, you could say, with microphones.
link |
In talking about the brief history of things,
link |
you said it's much harder to describe Sweden
link |
than it is the universe.
link |
So there's a lot of complexity.
link |
There was a lot of interesting details here.
link |
So how does this complexity come to be, do you think?
link |
It seems like there's these pockets.
link |
We don't know how rare of like where hairless apes emerge.
link |
And then that came from the initial soup
link |
that was homogeneous.
link |
Was that an accident?
link |
Well, we understand in broad outlines
link |
how it could happen.
link |
We certainly don't understand why it happened exactly
link |
in the way it did.
link |
Or there are certainly open questions
link |
about the origins of life
link |
and how inevitable the emergence of intelligence was
link |
and how that happened.
link |
But in the very broadest terms,
link |
the universe early on was quite homogeneous,
link |
but not completely homogeneous.
link |
There were part in 10,000 fluctuations in density
link |
within this primordial plasma.
link |
And as time goes on, there's an instability
link |
which causes those density contrasts to increase.
link |
There's a gravitational instability
link |
where it's denser, the gravitational attractions
link |
And so that brings in more matter
link |
and it gets even denser and so on and so on.
link |
So there's a natural tendency of matter to clump
link |
because of gravitational interactions.
link |
And then the equation is complicated.
link |
We have lots of things clumping together.
link |
Then we know what the laws are,
link |
but we have to a certain extent wave our hands
link |
about what happens.
link |
But basic understanding of chemistry
link |
says that if things and the physics of radiation
link |
tells us that as things start to clump together,
link |
they can radiate, give off some energy.
link |
So they don't just, they slow down.
link |
As a result, they lose energy.
link |
They can collaborate together, cool down,
link |
form things like stars, form things like planets.
link |
And so in broad terms, there's no mystery.
link |
There's, that's what the scenario,
link |
that's what the equations tell you should happen.
link |
But because it's a process involving
link |
many, many fundamental individual units,
link |
the application of the laws that govern individual units
link |
to these things is very delicate,
link |
computationally very difficult.
link |
And more profoundly, the equations have
link |
this probability of chaos or sensitivity
link |
to initial conditions, which tells you tiny differences
link |
in the initial state can lead to enormous differences
link |
in the subsequent behavior.
link |
So physics, fundamental physics at some point says,
link |
okay, chemists, biologists, this is your problem.
link |
And then again, in broad terms,
link |
we know how it's conceivable that the humans
link |
and things like that, how complex structure can emerge.
link |
It's a matter of having the right kind of temperature
link |
and the right kind of stuff.
link |
So you need to be able to make chemical bonds
link |
that are reasonably stable
link |
and be able to make complex structures.
link |
And we're very fortunate that carbon has this ability
link |
to make backbones and elaborate branchings and things.
link |
So you can get complex things that we call biochemistry.
link |
And yet the bonds can be broken a little bit
link |
with the help of energetic injections from the sun.
link |
So you have to have both the possibility of changing,
link |
but also the useful degree of stability.
link |
And we know at that very, very broad level, physics
link |
can tell you that it's conceivable.
link |
If you want to know what really happened,
link |
what really can happen, then you have to work a bit,
link |
If you want to know what actually happened,
link |
then you really have to consult the fossil record
link |
And so these ways of addressing the issue
link |
are complimentary in a sense.
link |
They use different kinds of concepts,
link |
they use different languages
link |
and they address different kinds of questions,
link |
but they're not inconsistent, they're just complimentary.
link |
It's kind of interesting to think about those early fluctuations
link |
as our earliest ancestors.
link |
Yes, that's right.
link |
So it's amazing to think that this is the modern answer
link |
to the, or the modern version of what the Hindu philosophers
link |
had, that art thou.
link |
If you ask what, okay, those little quantum fluctuations
link |
in the early universe are the seeds out of which complexity,
link |
including plausibly humans, really evolve.
link |
You don't need anything else.
link |
That brings up the question of asking for a friend here
link |
if there's other pockets of complexity,
link |
commonly called as alien intelligent civilizations out there.
link |
Well, we don't know for sure,
link |
but I have a strong suspicion that the answer is yes
link |
because the one case we do have at hand to study
link |
here on Earth, we sort of know what the conditions were
link |
that were helpful to life,
link |
the right kind of temperature, the right kind of star
link |
that keeps, maintains that temperature for a long time,
link |
the liquid environment of water.
link |
And once those conditions emerged on Earth,
link |
which was roughly four and a half billion years ago,
link |
it wasn't very long before what we call life
link |
started to leave relics.
link |
So we can find forms of life, primitive forms of life
link |
that are almost as old as the Earth itself
link |
in the sense that once the Earth was turned
link |
from a very hot boiling thing
link |
and cooled off into a solid mass with water,
link |
life emerged very, very quickly.
link |
So it seems that these general conditions for life
link |
are enough to make it happen relatively quickly.
link |
Now, the other lesson I think that one can draw
link |
from this one example, it's dangerous to draw lessons
link |
from one example, but that's all we've got,
link |
and that the emergence of intelligent life
link |
is a different issue altogether.
link |
That took a long time and seems to have been
link |
pretty contingent for a long time.
link |
Well, for most of the history of life,
link |
it was single celled things.
link |
Even multicellular life only rose
link |
about 600 million years ago, so much after.
link |
And then intelligence is kind of a luxury.
link |
Many more kinds of creatures have big stomachs
link |
In fact, most have no brains at all in any reasonable sense.
link |
And the dinosaurs ruled for a long, long time
link |
and some of them were pretty smart,
link |
but they were at best bird brains
link |
because birds came from the dinosaurs.
link |
And it could have stayed that way.
link |
And then the emergence of humans was very contingent
link |
and kind of a very, very recent development
link |
on evolutionary timescales.
link |
And you can argue about the level of human intelligence,
link |
but I think that's what we're talking about.
link |
It's very impressive and can ask these kinds of questions
link |
and discuss them intelligently.
link |
So I guess my, so this is a long winded answer
link |
or justification of my feeling
link |
is that the conditions for life in some form
link |
are probably satisfied many, many places
link |
around the universe and even within our galaxy.
link |
I'm not so sure about the emergence of intelligent life
link |
or the emergence of technological civilizations.
link |
That seems much more contingent and special.
link |
And we might, it's conceivable to me
link |
that we're the only example in the galaxy.
link |
Although, yeah, I don't know one way or the other.
link |
I have different opinions on different days of the week.
link |
But one of the things that worries me
link |
in the spirit of being humble,
link |
that our particular kind of intelligence
link |
is not very special.
link |
So there's all kinds of different intelligences.
link |
And even more broadly,
link |
there could be many different kinds of life.
link |
So the basic definition, and I just had,
link |
I think somebody that you know, Sarah Walker,
link |
I just had a very long conversation with her
link |
about even just the very basic question
link |
of trying to define what is life from a physics perspective.
link |
Even that question within itself,
link |
I think one of the most fundamental questions
link |
in science and physics and everything
link |
is just trying to get a hold,
link |
trying to get some universal laws
link |
around the ideas of what is life
link |
because that kind of unlocks a bunch of things
link |
around life, intelligence, consciousness,
link |
all those kinds of things.
link |
I agree with you in a sense,
link |
but I think that's a dangerous question
link |
because the answer can't be any more precise
link |
than the question.
link |
And the question, what is life,
link |
kind of assumes that we have a definition of life
link |
and that it's a natural phenomena
link |
that can be distinguished.
link |
But really there are edge cases like viruses
link |
and some people would like to say
link |
that electrons have consciousness.
link |
So you can't, if you really have fuzzy concepts,
link |
it's very hard to reach precise kinds of scientific answers.
link |
But I think there's a very fruitful question
link |
that's adjacent to it,
link |
which has been pursued in different forms
link |
and is now becoming very sophisticated
link |
in reaching in new directions.
link |
And that is, what are the states of matter
link |
that are possible?
link |
So in high school or grade school,
link |
you learn about solids, liquids and gases,
link |
but that really just scratches the surface
link |
of different ways that are distinguishable,
link |
that matter can form into macroscopically different,
link |
meaningful patterns that we call phases.
link |
And then there are precise definitions
link |
of what we mean by phases of matter
link |
and that have been worked out fruitful over the decades.
link |
And we're discovering new states of matter all the time
link |
and kind of having to work at what we mean by matter.
link |
We're discovering the capabilities of matter
link |
to organize in interesting ways.
link |
And some of them, like liquid crystals,
link |
are important ingredients of life.
link |
Our cell membranes are liquid crystals,
link |
and that's very important to the way they work.
link |
Recently, there's been a development
link |
in where we're talking about states of matter
link |
that are not static, but that have dynamics,
link |
that have characteristic patterns,
link |
not only in space, but in time.
link |
These are called time crystals,
link |
and that's been a development
link |
that's just in the last decade or so.
link |
It's just really, really flourishing.
link |
And so is there a state of matter
link |
or a group of states of matter that corresponds to life?
link |
Maybe, but the answer can't be any more definite
link |
than the question.
link |
I mean, I gotta push back on the,
link |
those are just words.
link |
I mean, I disagree with you.
link |
The question points to a direction.
link |
The answer might be able to be more precise
link |
than the question, because just as you're saying,
link |
there is a, we could be discovering
link |
certain characteristics and patterns
link |
that are associated with a certain type of matter,
link |
macroscopically speaking,
link |
and that we can then be able to post facto say,
link |
this is, let's assign the word life to this kind of matter.
link |
I agree with that completely, that's what that's,
link |
but that's, so it's not a disagreement.
link |
It's very frequent in physics that, or in science,
link |
that words that are in common use
link |
get refined and reprocessed into scientific terms
link |
that's happened for things like force and energy.
link |
And so we, in a way, we find out
link |
what the useful definition is, or symmetry, for instance.
link |
And the common usage may be quite different
link |
from the scientific usage,
link |
but the scientific usage is special
link |
and takes on a life of its own,
link |
and we find out what the useful version of it is,
link |
the fruitful version of it is.
link |
So I do think, so in that spirit,
link |
I think if we can identify states of matter
link |
or linked states of matter that can carry on processes
link |
of self reproduction and development
link |
and information processing,
link |
we might be tempted to classify those things as life.
link |
Well, can I ask you about the craziest one,
link |
which is the one we know maybe least about,
link |
which is consciousness.
link |
Is it possible that there are certain kinds of matter
link |
would be able to classify as conscious,
link |
meaning like, so there's the panpsychists, right,
link |
who are the philosophers who kind of try to imply
link |
that all matter has some degree of consciousness,
link |
and you can almost construct like a physics of consciousness.
link |
Do you, again, we're in such early days of this,
link |
but nevertheless, it seems useful to talk about it.
link |
Is there some sense from a physics perspective
link |
to make sense of consciousness?
link |
Is there some hope?
link |
Well, again, consciousness is a very imprecise word
link |
and loaded with connotations that I think we should,
link |
we don't wanna start a scientific analysis with that,
link |
It's often been important in science
link |
to start with simple cases and work up.
link |
Consciousness, I think what most people think of
link |
when you talk about consciousness is,
link |
okay, what am I doing in the world?
link |
This is my experience.
link |
I have a rich inner life and experience,
link |
and where is that in the equations?
link |
And I think that's a great question,
link |
a great, great question,
link |
and actually, I think I'm gearing up to spend part of,
link |
I mean, to try to address that in coming years.
link |
One version of asking that question,
link |
just as you said now,
link |
is what is the simplest formulation of that to study?
link |
I think I'm much more comfortable
link |
with the idea of studying self awareness
link |
as opposed to consciousness,
link |
because that sort of gets rid of the mystical aura of the thing.
link |
And self awareness is in simple,
link |
you know, I think contiguous at least
link |
with ideas about feedback.
link |
So if you have a system that looks at its own state
link |
and responds to it, that's a kind of self awareness.
link |
And more sophisticated versions
link |
could be like in information processing things,
link |
computers that look into their own internal state
link |
and do something about it.
link |
And I think that could also be done in neural nets.
link |
This is called recurrent neural nets,
link |
which are hard to understand and kind of a frontier.
link |
So I think understanding those
link |
and gradually building up a kind of profound ability
link |
to conceptualize different levels of self awareness.
link |
What do you have to not know?
link |
And what do you have to know?
link |
And when do you know that you don't know it?
link |
Or when do you, what do you think you know
link |
that you don't really know?
link |
And these, I think clarifying those issues,
link |
when we clarify those issues
link |
and get a rich theory around self awareness,
link |
I think that will illuminate the questions
link |
about consciousness in a way that, you know,
link |
scratching your chin and talking about qualia
link |
and blah, blah, blah, blah is never gonna do.
link |
Well, I also have a different approach to the whole thing.
link |
So there's, from a robotics perspective,
link |
you can engineer things that exhibit qualities
link |
of consciousness without understanding how things work.
link |
And from that perspective, you, it's like a back door,
link |
like enter through the psychology door.
link |
Precisely, I think we're on the same wavelength here.
link |
I think that, and let me just add one comment,
link |
which is I think we should try to understand consciousness
link |
as we experience it as, in evolutionary terms,
link |
and ask ourselves, why, why does it happen?
link |
This thing seems useful.
link |
Interesting question.
link |
I think we've got a conscious eyewatch here.
link |
Interesting question.
link |
I'll get back to you later.
link |
The, and I think what we're gonna,
link |
I'm morally certain that what's gonna emerge
link |
from analyzing recurrent neural nets
link |
and robotic design and advanced computer design
link |
is that having this kind of looking at the internal state
link |
in a structured way that doesn't look at everything,
link |
this guy's has, it's encapsulated,
link |
looks at highly processed information,
link |
is very selective and makes choices
link |
without knowing how they're made.
link |
There's, there'll also be an unconscious.
link |
I think that that is gonna be,
link |
turn out to be really essential
link |
to doing efficient information processing.
link |
And that's why it evolved,
link |
because it's, it's, it's, it's helpful in,
link |
because brains come at a high cost.
link |
So there has to be, there has to be a good why.
link |
And there's a reason, yeah.
link |
They're rare in evolution and big brains
link |
are rare in evolution and they, they come at a big cost.
link |
You mean, if you, you, they, they,
link |
they have high metabolic demands.
link |
They require, you know, very active lifestyle,
link |
warm bloodedness and take, take away from the ability
link |
to support metabolism of digestion.
link |
And so, so it's, it's, it comes at a high cost.
link |
It has to, it has to pay back.
link |
Yeah, I think it has a lot of value in social interaction.
link |
So I actually am spending the rest of the day today
link |
and with our friends that are,
link |
our legged friends in robotic form at Boston Dynamics.
link |
And I think, so my probably biggest passion
link |
is human robot interaction.
link |
And it seems that consciousness from the perspective
link |
of the robot is very useful to improve
link |
the human robot interaction experience.
link |
The first, the display of consciousness,
link |
but then to me, there's a gray area
link |
between the display of consciousness and consciousness itself.
link |
If you think of consciousness
link |
from an evolutionary perspective,
link |
it seems like a useful tool in human communication, so.
link |
Yes, it's certainly, well,
link |
whatever consciousness is will turn out to be.
link |
I think addressing it through its use
link |
and working up from simple cases
link |
and also working up from engineering experience
link |
in trying to do efficient computation,
link |
including efficient management of social interactions
link |
is going to really shed light on these questions.
link |
As I said, in a way that sort of musing abstractly
link |
about consciousness never would.
link |
So as I mentioned, I talked to Sarah Walker
link |
and first of all, she says, hi, spoke very highly of you.
link |
One of her concerns about physics and physicists and humans
link |
is that we may not fully understand the system
link |
that we're inside of.
link |
Meaning like, there may be limits
link |
to the kind of physics we do
link |
in trying to understand the system of which we're part of.
link |
So like, the observer is also the observed.
link |
In that sense, it seems like
link |
our tools of understanding the world,
link |
I mean, this is mostly centered around the questions
link |
of what is life, trying to understand the patterns
link |
that are characteristic of life and intelligence,
link |
all those kinds of things.
link |
We're not using the right tools because we're in the system.
link |
Is there something that resonates with you there?
link |
Well, yes, we have limitations, of course,
link |
in the amount of information we can process.
link |
On the other hand, we can get help from our Silicon friends
link |
and we can get help from all kinds of instruments
link |
that make up for our perceptual deficits.
link |
And we can use, at a conceptual level,
link |
we can use different kinds of concepts
link |
to address different kinds of questions.
link |
So I'm not sure exactly what problem she's talking about.
link |
It's a problem akin to an organism living in a 2D plane
link |
trying to understand a three dimensional world.
link |
Well, we can do that.
link |
I mean, in fact, for practical purposes,
link |
most of our experience is two dimensional.
link |
It's hard to move vertically.
link |
And yet we've produced conceptually
link |
a three dimensional symmetry
link |
and in fact, four dimensional space time.
link |
So by thinking in appropriate ways and using instruments
link |
and getting consistent accounts and rich accounts,
link |
we find out what concepts are necessary.
link |
And I don't see any end in sight of the process
link |
or any showstoppers because, let me give you an example.
link |
I mean, for instance, QCD,
link |
our theory of the strong interaction,
link |
has nice equations, which I helped to discover.
link |
Quantum chromodynamics.
link |
So it's our theory of the strong interaction,
link |
the interaction that is responsible for nuclear physics.
link |
So it's the interaction that governs
link |
how quarks and gluons interact with each other
link |
and make protons and neutrons
link |
and all the strong, the related particles
link |
and many things in physics.
link |
It's one of the four basic forces of nature
link |
as we presently understand it.
link |
And so we have beautiful equations,
link |
which we can test in very special circumstances
link |
using at high energies, at accelerators.
link |
So we're certain that these equations are correct.
link |
Prizes are given for it and so on.
link |
And people try to knock it down and they can't.
link |
Yeah, but the situations in which we can calculate
link |
the consequences of these equations are very limited.
link |
So for instance, no one has been able to demonstrate
link |
that this theory, which is built on quarks and gluons,
link |
which no one, which you don't observe,
link |
actually produces protons and neutrons
link |
and the things you do observe.
link |
This is called the problem of confinement.
link |
So no one's been able to prove that analytically
link |
in a way that a human can understand.
link |
On the other hand, we can take these equations
link |
to a computer, to gigantic computers and compute.
link |
And by God, you get the world from it.
link |
So these equations in a way that we don't understand
link |
in terms of human concepts, we can't do the calculations,
link |
but our machines can do them.
link |
So with the help of what I like to call our silicon friends
link |
and their descendants in the future,
link |
we can understand in a different way
link |
that allows us to understand more.
link |
But I don't think we'll ever, no human is ever going
link |
to be able to solve those equations in the same way.
link |
So, but I think that's, you know,
link |
when we find limitations to our natural abilities,
link |
we can try to find workarounds.
link |
And sometimes that's appropriate concepts.
link |
Sometimes it's appropriate instruments.
link |
Sometimes it's a combination of the two.
link |
But I think it's premature to get defeatist about it.
link |
I don't see any logical contradiction
link |
or paradox or limitation
link |
that will bring this process to a halt.
link |
Well, I think the idea is to continue thinking
link |
outside the box in different directions,
link |
meaning just like how the math allows us
link |
to think in multiple dimensions
link |
outside of our perception system, sort of thinking,
link |
you know, coming up with new tools
link |
of mathematics or computation or all those kinds of things
link |
to take different perspectives on our universe.
link |
Well, I'm all for that.
link |
You know, and I kind of have even elevated into a principle
link |
which is of complementarity following Bohr
link |
that you need different ways of thinking
link |
even about the same things
link |
in order to do justice to their reality
link |
and answer different kinds of questions about them.
link |
I mean, we've several times alluded to the fact
link |
that human beings are hard to understand
link |
and the concepts that you use to understand human beings
link |
if you wanna prescribe drugs for them
link |
or see what's gonna happen if they move very fast
link |
or are exposed to radiation.
link |
And so that requires one kind of thinking
link |
that's very physical based on the fact
link |
that the materials that were made out of.
link |
On the other hand, if you want to understand
link |
how a person's going to behave
link |
in a different kind of situation,
link |
you need entirely different concepts from psychology
link |
and there's nothing wrong with that.
link |
You can have very different ways
link |
of addressing the same material
link |
that are useful for different purposes, right?
link |
Can you describe this idea
link |
which is fascinating of complementarity a little bit?
link |
Sort of first of all, what state is the principle?
link |
And second of all, what are good examples
link |
starting from quantum mechanics?
link |
You used to mention psychology.
link |
Let's talk about this more.
link |
It's like in your new book
link |
one of the most fascinating ideas actually.
link |
I think it's a wonderful, yeah.
link |
To me it's, well, it's the culminating chapter of the book
link |
and I think since the whole book is about the big lessons
link |
or big takeaways from profound understanding
link |
of the physical world that we've achieved,
link |
including that it's mysterious in some ways,
link |
this was the final overarching lesson, complementarity.
link |
Lesson, complementarity and it's a approach.
link |
So unlike some of these other things
link |
which are just facts about the world,
link |
like the world is both big and small
link |
and different sizes and is big but we're not small,
link |
things we talked about earlier
link |
and the fact that the universe is comprehensible
link |
and how complexity could emerge from simplicity
link |
and so those things are in the broad sense
link |
facts about the world.
link |
Complementarity is more an attitude towards the world
link |
than encouraged by the facts about the world.
link |
And it's the concept or the approach
link |
or the realization that it can be appropriate
link |
and useful and inevitable and unavoidable
link |
to use very different descriptions of the same object
link |
or the same system or the same situation
link |
to answer different kinds of questions
link |
that may be very different
link |
and even mutually uninterpretable,
link |
immutually incomprehensible.
link |
But both correct somehow.
link |
But both correct and sources of different kinds of insight
link |
which is so weird.
link |
But it seems to work in so many cases.
link |
It works in many cases and I think it's a deep fact
link |
about the world and how we should approach it.
link |
It's most rigorous form where it's actually a theorem
link |
if quantum mechanics is correct,
link |
occurs in quantum mechanics
link |
where the primary description of the world
link |
is in terms of wave functions.
link |
But let's not talk about the world.
link |
Let's just talk about a particle, an electron.
link |
The primary description of that electron
link |
is its wave function.
link |
And the wave function can be used to predict
link |
where it's gonna be.
link |
If you observe, it'll be in different places
link |
with different probabilities or how fast it's moving.
link |
And it'll also be moving in different ways
link |
with different probabilities.
link |
That's what quantum mechanics says.
link |
And you can predict either set of probabilities
link |
if you know what's gonna happen
link |
if I make an observation of the position or the velocity.
link |
So the wave function gives you ways of doing both of those.
link |
But to do it, to get those predictions,
link |
you have to process the wave function in different ways.
link |
You process it one way for position
link |
and in a different way for momentum.
link |
And those ways are mathematically incompatible.
link |
It's like you have a stone
link |
and you can sculpt it into a Venus de Milo
link |
or you can sculpt it into David, but you can't do both.
link |
And that's an example of complementarity.
link |
To answer different kinds of questions,
link |
you have to analyze the system in different ways
link |
that are mutually incompatible,
link |
but both valid to answer different kinds of questions.
link |
So in that case, it's a theorem,
link |
but I think it's a much more widespread phenomena
link |
that applies to many cases
link |
where we can't prove it as a theorem,
link |
but it's a piece of wisdom, if you like,
link |
and appears to be a very important insight.
link |
And if you ignore it,
link |
you can get very confused and misguided.
link |
Do you think this is a useful hack
link |
for ideas that we don't fully understand?
link |
Or is this somehow a fundamental property
link |
of all or many ideas,
link |
that you can take multiple perspectives
link |
and they're both true?
link |
Well, I think it's both.
link |
So it's both the answer to all questions.
link |
Yes, that's right.
link |
It's not either or, it's both.
link |
It's paralyzing to think that we live in a world
link |
that's fundamentally surrounded by complementary ideas.
link |
Because we somehow want to attach ourselves
link |
to absolute truths,
link |
and absolute truths certainly don't like the idea
link |
of complementarity.
link |
Yes, Einstein was very uncomfortable with complementarity.
link |
And in a broad sense,
link |
the famous Bohr Einstein debates
link |
revolved around this question
link |
of whether the complementarity
link |
that is a foundational feature of quantum mechanics,
link |
is a permanent feature of the universe
link |
and our description of nature.
link |
And so far, quantum mechanics wins.
link |
And it's gone from triumph to triumph.
link |
Whether complementarity is rock bottom,
link |
I guess, you can never be sure.
link |
I mean, but it looks awfully good
link |
and it's been very successful.
link |
And certainly, complementarity has been extremely useful
link |
and fruitful in that domain,
link |
including some of Einstein's attempts to challenge it
link |
with the famous Einstein Podolsky Rosen experiment
link |
turned out to be confirmations
link |
that have been useful in themselves.
link |
But so thinking about these things was fruitful,
link |
but not in the way that Einstein hoped.
link |
Yeah, so as I said, in the case of quantum mechanics
link |
and this dilemma or dichotomy
link |
between processing the wave function in different ways,
link |
They're mutually incompatible
link |
and the physical correlate of that
link |
is the Heisenberg uncertainty principle
link |
you can't have position and momentum determined at once.
link |
But in other cases, like one that I like to think about
link |
or like to point out as an example
link |
is free will and determinism.
link |
It's much less of a theorem
link |
and more a kind of way of thinking about things
link |
that I think is reassuring
link |
and avoids a lot of unnecessary quarreling and confusion.
link |
The quarreling I'm okay with
link |
and the confusion I'm okay with,
link |
I mean, people debate about difficult ideas,
link |
but the question is whether it could be
link |
almost a fundamental truth.
link |
I think it is a fundamental truth.
link |
That free will is both an illusion and not.
link |
Yes, I think that's correct.
link |
There's a reason why people say quantum mechanics is weird
link |
and complementarity is a big part of that.
link |
To say that our actual whole world is weird,
link |
the whole hierarchy of the universe is weird
link |
in this kind of particular way,
link |
and it's quite profound, but it's also humbling
link |
because it's like we're never going to be on sturdy ground
link |
in the way that humans like to be.
link |
It's like you have to embrace that this whole thing
link |
is like unsteady mess.
link |
It's one of many lessons in humility
link |
that we run into in profound understanding of the world.
link |
The Copernican revolution was one,
link |
that the earth is not the center of the universe.
link |
Darwinian evolution is another,
link |
that humans are not the pinnacle of God's creation and the apparent result
link |
of deep understanding of physical reality,
link |
that mind emerges from matter and there's no call
link |
on special life forces or souls.
link |
These are all lessons in humility,
link |
and I actually find complementarity a liberating concept.
link |
It's, okay, you know, we...
link |
Yeah, it is in a way.
link |
That is what I remember.
link |
There's a story about Dr. Johnson,
link |
and he's talking with Boswell,
link |
and Boswell was, they were discussing a sermon
link |
that they'd both heard,
link |
and the sort of culmination of the sermon was the speaker saying,
link |
I accept the universe.
link |
And Dr. Johnson said, well, damn well better.
link |
And there's a certain joy in accepting the universe
link |
because it's mind expanding.
link |
And to me, complementarity also suggests tolerance,
link |
suggests opportunities for understanding things
link |
in different ways that add to rather than detract
link |
from understanding.
link |
So I think it's an opportunity for mind expansion
link |
and demanding that there's only one way
link |
to think about things can be very limiting.
link |
On the free will one, that's a trippy one, though.
link |
To think like I am the decider of my own actions
link |
and at the same time I'm not is tricky to think about,
link |
but there does seem to be some kind of profound truth in that.
link |
I get, well, I think it is tied up.
link |
It will turn out to be tied up when we understand things better
link |
with these issues of self awareness and where we get,
link |
what we perceive as making choices,
link |
what does that really mean and what's going on under the hood.
link |
But I'm speculating about a future understanding
link |
that's not in place at present.
link |
Your sense there will always be,
link |
like as you dig into the self awareness thing,
link |
there'll always be some places
link |
where complementarity is gonna show up.
link |
Oh, definitely, yeah.
link |
I mean, there will be, how should I say?
link |
There'll be kind of a God's eye view
link |
which sees everything that's going on
link |
in the computer or the brain.
link |
And then there's the brain's own view
link |
or the central processor or whatever it is,
link |
what we call the self, the consciousness,
link |
that's only aware of a very small part of it.
link |
And those are very different.
link |
Those are, so the God's eye view can be deterministic
link |
while the self view sees free will.
link |
I'm pretty sure that's how it's gonna work out actually.
link |
But as it stands, free will is a concept
link |
that we definitely, at least I feel I definitely experience,
link |
I can choose to do one thing then another.
link |
And other people I think are sufficiently similar to me
link |
that I trust that they feel the same way.
link |
And it's an essential concept in psychology
link |
and law and so forth.
link |
But at the same time, I think that mind emerges from matter
link |
and that there's an alternative description of matter
link |
that's up to subtleties about quantum mechanics,
link |
which I don't think are relevant here,
link |
really is deterministic.
link |
Let me ask you about some particles.
link |
First the absurd question,
link |
almost like a question that like Plato would ask.
link |
What is the smallest thing in the universe?
link |
As far as we know, the fundamental particles
link |
out of which we build our most successful description
link |
of nature are points.
link |
They don't have any internal structure.
link |
So that's as small as can be.
link |
So what does that mean operationally?
link |
That means that they obey equations that describe entities
link |
that are singular concentrations of energy,
link |
momentum, angular momentum,
link |
the things that particles have,
link |
but localized at individual points.
link |
Now that mathematical structure
link |
is only revealed partially in the world
link |
because to process the wave function
link |
in a way that accesses information about the precise
link |
position of things, you have to apply a lot of energy
link |
and that's an idealization
link |
and you can apply infinite amount of energy
link |
to determine a precise position.
link |
But at the mathematical level,
link |
we build the world out of particles that are points.
link |
So do they actually exist and what are we talking about?
link |
So let me ask sort of do quarks exist?
link |
Yes, do electrons exist?
link |
Yes, do photons exist?
link |
But what does it mean for them to exist?
link |
Okay, so well, the hard answer to that,
link |
the precise answer is that we construct the world
link |
out of equations that contain entities
link |
that are reproducible,
link |
that exist in vast numbers throughout the universe,
link |
that have definite properties of mass,
link |
spin and a few others that we call electrons
link |
and what an electron is is defined by the equations
link |
that it satisfies theoretically
link |
and we find that there are many, many exemplars
link |
of that entity in the physical world.
link |
So in the case of electrons,
link |
we can isolate them and study them
link |
and individual ones in great detail
link |
and we can check that they all actually are identical
link |
and that's why chemistry works and yes.
link |
So in that case, it's very tangible.
link |
Similarly with photons,
link |
you can study them individually, the units of light
link |
and nowadays, it's very practical
link |
to study individual photons
link |
and determine their spin and their other basic properties
link |
and check out the equations in great detail.
link |
For quarks and gluons,
link |
which are the other two main ingredients
link |
of our model of matter that's so successful,
link |
it's a little more complicated
link |
because the quarks and gluons that appear in our equations
link |
don't appear directly as particles you can isolate
link |
and study individually.
link |
They always occur within what are called bound states
link |
or structures like protons.
link |
A proton, roughly speaking, is composed of three quarks
link |
and a lot of gluons but we can detect them
link |
in a remarkably direct way actually nowadays,
link |
whereas at relatively low energies,
link |
the behavior of quarks is complicated.
link |
At high energies, they can propagate through space
link |
relatively freely for a while and we can see their tracks.
link |
So ultimately, they get recaptured into protons
link |
and other mesons and funny things
link |
but for a short time, they propagate freely
link |
and while that happens, we can take snapshots
link |
and see their manifestations.
link |
Actually, this kind of thing is exactly
link |
what I got the Nobel Prize for,
link |
predicting that this would work.
link |
And similarly for gluons,
link |
although you can't isolate them as individual particles
link |
and study them in the same way that we study electrons,
link |
say, you can use them theoretically as entities
link |
out of which you build tangible things
link |
that we actually do observe
link |
but also you can, at accelerators at high energy,
link |
you can liberate them for brief periods of time
link |
and study and get convincing evidence
link |
that they leave tracks and you can get convincing evidence
link |
that they were there and have the properties
link |
that we wanted them to have.
link |
Can we talk about asymptotic freedom,
link |
this very idea that you won the Nobel Prize for?
link |
So it describes a very weird effect to me,
link |
the weird in the following way.
link |
So the way I think of most forces or interactions,
link |
the closer you are, the stronger the effect,
link |
the stronger the force, right?
link |
With quarks, the close they are,
link |
the less so the strong interaction.
link |
And in fact, they're basically act like free particles
link |
when they're very close.
link |
That's right, yes.
link |
But this requires a huge amount of energy.
link |
Like can you describe me why, how does this even work?
link |
A proper description must bring in quantum mechanics
link |
and relativity and it's,
link |
so a proper description and equations,
link |
so a proper description really is probably more
link |
than we have time for and require quite a bit of patience
link |
on your part, but.
link |
How does relativity come into play?
link |
Wait, wait a minute.
link |
Relativity is important because when we talk about
link |
trying to think about short distances,
link |
we have to think about very large momenta
link |
and very large momenta are connected
link |
to very large energy in relativity.
link |
And so the connection between how things behave
link |
at short distances and how things behave at high energy
link |
really is connected through relativity
link |
in sort of a slightly backhanded way.
link |
Quantum mechanics indicates that short,
link |
to get to analyze short distances,
link |
you need to bring in probes that carry a lot of momentum.
link |
This again is related to uncertainty
link |
because it's the fact that you have to bring in
link |
a lot of momentum that interferes with the possibility
link |
of determining position and momentum at the same time.
link |
If you want to determine position,
link |
you have to use instruments that bring in a lot of momentum.
link |
And because of that, those same instruments
link |
can't also measure momentum
link |
because they're disturbing the momentum that,
link |
and then the momentum brings in energy and yeah.
link |
So that there's also the effect that asymptotic freedom
link |
comes from the possibility of spontaneously making
link |
quarks and gluons for short amounts of time
link |
that fluctuate into existence and out of existence.
link |
And the fact that that can be done
link |
with a very little amount of energy
link |
and uncertainty and energy translates
link |
into uncertainty and time.
link |
So if you do that for a short time, you can do that.
link |
Well, it's all comes in a package.
link |
So I told you it would take a while to really explain,
link |
but the results can be understood.
link |
I mean, we can state the results pretty simply, I think.
link |
So in everyday life, we do encounter some forces
link |
that increase with distance
link |
and kind of turn off at short distances.
link |
That's the way rubber bands work, if you think about it,
link |
or if you pull them hard, they resist,
link |
but they get flabby if the rubber band is not pulled.
link |
And so there are, that can happen in the physical world,
link |
but what's really difficult is to see
link |
how that could be a fundamental force
link |
that's consistent with everything else we know.
link |
And that's what asymptotic freedom is.
link |
It says that there's a very particular kind
link |
of fundamental force that involves special particles
link |
called gluons with very special properties
link |
that enables that kind of behavior.
link |
So there were experiment, at the time we did our work,
link |
there were experimental indications
link |
that quarks and gluons did have this kind of property,
link |
but there were no equations
link |
that were capable of capturing it.
link |
And we found the equations and showed how they work
link |
and showed how they, that they were basically unique.
link |
And this led to a complete theory
link |
of how the strong interaction works,
link |
which is the quantum chromodynamics we mentioned earlier.
link |
And so that's the phenomenon that quarks and gluons
link |
interact very, very weakly when they're close together.
link |
That's connected through relativity
link |
with the fact that they also interact very, very weakly
link |
So if you have, so at high energies,
link |
the simplicity of the fundamental interaction gets revealed.
link |
At the time we did our work,
link |
the clues were very subtle,
link |
but nowadays at what are now high energy accelerators,
link |
So we would have had a much,
link |
well, somebody would have had a much easier time
link |
20 years later, looking at the data,
link |
you can sort of see the quarks and gluons.
link |
As I mentioned, they leave these short tracks
link |
that would have been much, much easier,
link |
but from fundamental, from indirect clues,
link |
we were able to piece together enough
link |
to make that behavior a prediction
link |
rather than a post diction, right?
link |
So it becomes obvious at high energies.
link |
It becomes very obvious.
link |
When we first did this work,
link |
it was frontiers of high energy physics
link |
and at big international conferences,
link |
there would always be sessions on testing QCD
link |
and whether this proposed description
link |
of the strong interaction was in fact correct and so forth.
link |
And it was very exciting.
link |
But nowadays the same kind of work,
link |
but much more precise with calculations
link |
to more accuracy and experiments
link |
that are much more precise
link |
and comparisons that are very precise.
link |
Now it's called calculating backgrounds
link |
because people take this for granted
link |
and wanna see deviations from the theory,
link |
which would be the new discoveries.
link |
Yeah, the cutting edge becomes a foundation
link |
and the foundation becomes boring.
link |
Is there some, for basic explanation purposes,
link |
is there something to be said about strong interactions
link |
in the context of the strong nuclear force
link |
for the attraction between protons and neutrons
link |
versus the interaction between quarks within protons?
link |
Well, quarks and gluons have the same relation
link |
basically to nuclear physics
link |
as electrons and photons have
link |
to atomic and molecular physics.
link |
So atoms and photons are the dynamic entities
link |
that really come into play in chemistry and atomic physics.
link |
Of course, you have to have the atomic nuclei,
link |
but those are small and relatively inert,
link |
really the dynamical part.
link |
And for most purposes of chemistry,
link |
you just say that you have this tiny little nucleus,
link |
which QCD gives you.
link |
Don't worry about it.
link |
It just, it's there.
link |
The real action is the electrons moving around
link |
and exchanging and things like that.
link |
Okay, but we want it to understand the nucleus too.
link |
And so atoms are sort of quantum mechanical clouds
link |
of electrons held together by electrical forces,
link |
And then this radiation,
link |
which is another aspect of photons.
link |
That's where all the fun happens
link |
is the electrons and the photons.
link |
Yeah, that's right.
link |
And the nucleus are kind of the,
link |
well, they give the positive charge
link |
and most of the mass of matter,
link |
but they don't, since they're so heavy,
link |
they don't move very much in chemistry.
link |
And I'm oversimplifying drastically.
link |
They're not contributing much to the interaction in chemistry.
link |
For most purposes in chemistry,
link |
you can just idealize them as concentrations
link |
of positive mass and charge that are,
link |
you don't have to look inside,
link |
but people are curious what's inside.
link |
And that was a big thing on the agenda
link |
of 20th century physics starting in the 19,
link |
well, starting with the 20th century
link |
and unfolding throughout of trying to understand
link |
what forces held the atomic nucleus together,
link |
what it was and so.
link |
Anyway, the story that emerges from QCD
link |
is that very similar to the way that,
link |
well, broadly similar to the way
link |
that clouds of electrons held together
link |
by electrical forces give you atoms
link |
and ultimately molecules.
link |
Protons and neutrons are like atoms
link |
made now out of quarks, quark clouds held together
link |
by gluons, which are like the photons
link |
that give the electric forces,
link |
but this is giving a different force, the strong force.
link |
And the residual forces between protons and neutrons
link |
that are leftover from the basic binding
link |
are like the residual forces between atoms
link |
that give molecules, but in the case of protons and neutrons,
link |
it gives you atomic nuclei.
link |
So again, for definitional purposes,
link |
QCD, quantum chromodynamics,
link |
is basically the physics of strong interaction.
link |
Yeah, we understand, we now would understand,
link |
I think most physicists would say
link |
it's the theory of quarks and gluons
link |
and how they interact.
link |
But it's a very precise, and I think it's fair to say,
link |
very beautiful theory based on mathematical symmetry
link |
of a high order, and another thing that's beautiful
link |
about it is that it's kind of
link |
in the same family as electrodynamics.
link |
The conceptual structure of the equations are very similar.
link |
They're based on having particles that respond to charge
link |
in a very symmetric way.
link |
In the case of electrodynamics,
link |
it's photons that respond to electric charge.
link |
In the case of quantum chromodynamics,
link |
there are three kinds of charge that we call colors,
link |
but they're nothing like colors.
link |
They really are like different kinds of charge.
link |
But they rhyme with the same kind of,
link |
like it's similar kind of dynamics.
link |
Similar kind of dynamics.
link |
I'd like to say that QCD is like QED on steroids.
link |
And instead of one photon, you have eight gluons.
link |
Instead of one charge, you have three color charges.
link |
But there's a strong family resemblance between them.
link |
But the context in which QCD does this thing
link |
is it's much higher energies.
link |
Like that's where it comes to life.
link |
Well, it's a stronger force,
link |
so that to access how it works and kind of pry things apart,
link |
you have to inject more energy.
link |
And so that gives us, in some sense,
link |
a hint of how things were in the earlier universe.
link |
Yeah, well, in that regard,
link |
asymptotic freedom is a tremendous blessing
link |
because it means things get simpler at high energy.
link |
The universe was born free.
link |
That's very good, yes.
link |
Universe was born.
link |
So in atomic physics,
link |
a similar thing happens in the theory of stars.
link |
Stars are hot enough that the interactions
link |
between electrons and photons, they're liberated.
link |
They don't form atoms anymore.
link |
They make a plasma,
link |
which in some ways is simpler to understand.
link |
You don't have complicated chemistry.
link |
And in the early universe, according to QCD,
link |
similarly atomic nuclei dissolved
link |
and take the constituent quarks and gluons,
link |
which are moving around very fast
link |
and interacting in relatively simple ways.
link |
And so this opened up the early universe
link |
to scientific calculation.
link |
Can I ask you about some other weird particles
link |
that make up our universe?
link |
And what is the strong CP problem?
link |
Okay, so let me start with what the strong CP problem is.
link |
First of all, well, C is charge conjugation,
link |
which is the transformation,
link |
the notional transformation, if you like,
link |
that changes all particles into their antiparticles.
link |
And the concept of C symmetry,
link |
charge conjugation symmetry, is that if you do that,
link |
you find the same laws that would work.
link |
So the laws are symmetric if the behavior
link |
that particles exhibit is the same
link |
as the behavior you get with all their antiparticles.
link |
And then P is parity,
link |
which is also called spatial inversion.
link |
It's basically looking at a mirror universe
link |
and saying that the laws that are obeyed
link |
in a mirror universe, when you look,
link |
that the mirror images obey the same laws
link |
as the sources of their images.
link |
There's no way of telling left from right, for instance,
link |
that the laws don't distinguish between left and right.
link |
Now, in the mid 20th century,
link |
people discovered that both of those are not quite true.
link |
Really, the equation that the mirror universe,
link |
the universe that you see in a mirror
link |
is not gonna obey the same laws
link |
as the universe that we actually interpret.
link |
You would be able to tell
link |
if you did the right kind of experiments,
link |
which was the mirror and which was the real thing.
link |
That's the parity and they show
link |
that the parity doesn't necessarily hold.
link |
It doesn't quite hold.
link |
Examining what the exceptions are turned out to be,
link |
to lead to all kinds of insight
link |
about the nature of fundamental interactions,
link |
especially properties of neutrinos
link |
and the weak interaction, it's a long story.
link |
But it's a very, it's a.
link |
So you just define the C and the P,
link |
the conjugation, the charge conjugation.
link |
Now that I've done that, I wanna.
link |
What's the problem?
link |
Because it's easier to talk about T,
link |
which is time reversal symmetry.
link |
We have very good reasons to think CPT
link |
is an accurate symmetry of nature.
link |
It's on the same level as relativity
link |
and quantum mechanics, basically.
link |
So that better be true.
link |
So it's symmetric when you.
link |
When you do conjugation parity and time.
link |
And time and space reversal.
link |
If you do all three,
link |
then you get the same physical consequences.
link |
Now, so, but that means that CP is equivalent to T.
link |
But what's observed in the world
link |
is that T is not quite an accurate symmetry of nature,
link |
So most phenomena of, at the fundamental level.
link |
So interactions among elementary particles
link |
and the basic gravitational interaction.
link |
If you ran them backwards in time,
link |
you'd get the same laws.
link |
So if, again, going back.
link |
This time we don't talk about a mirror,
link |
but we talk about a movie.
link |
If you take a movie and then run it backwards,
link |
that's the time reversal.
link |
It's good to think about a mirror in time.
link |
Yeah, it's like a mirror in time.
link |
If you run the movie backwards,
link |
it would look very strange
link |
if you were looking at complicated objects
link |
and a Charlie Chaplin movie or whatever.
link |
It would look very strange if you ran it backwards in time.
link |
But at the level of basic interactions,
link |
if you were able to look at the atoms
link |
and the quarks involved, they would obey the same laws.
link |
They do a very good approximation, but not exactly.
link |
So this is not exactly, that means you could tell.
link |
You could tell, but you'd have to do very, very
link |
subtle experiments with at high energy accelerators
link |
to take a movie that looked different
link |
when you ran it backwards.
link |
This was a discovery by two great physicists
link |
named Jim Cronin and Val Fitch in the mid 1960s.
link |
Previous to that, over all the centuries
link |
of development of physics with all its precise laws,
link |
they did seem to have this gratuitous property
link |
that they look the same if you run the equations backwards.
link |
It's kind of an embarrassing property actually
link |
because life isn't like that.
link |
So empirical reality does not have this imagery
link |
in any obvious way.
link |
And yet the laws did.
link |
It's almost like the laws of physics
link |
are missing something fundamental about life
link |
if it holds that property, right?
link |
Well, that's the embarrassing nature of it.
link |
Yeah, it's embarrassing.
link |
Well, people worked hard at what's,
link |
this is a problem that's thought to belong
link |
to the foundations of statistical mechanics
link |
or the foundations of thermodynamics
link |
to understand how behavior,
link |
which is grossly not symmetric
link |
with respect to reversing the direction of time
link |
in large objects, how that can emerge from equations
link |
which are symmetric with respect to changing
link |
the direction of time to a very good approximation.
link |
And that's still an interesting endeavor.
link |
That's interesting.
link |
And actually it's an exciting frontier of physics now
link |
to sort of explore the boundary
link |
between when that's true and when it's not true.
link |
When you get to smaller objects
link |
and exceptions like time crystals.
link |
I definitely have to ask you about time crystals
link |
But so the CP problem and T,
link |
so there's all of these.
link |
We're in danger of infinite regress,
link |
but we have to convert soon.
link |
Can't possibly be turtles all the way down.
link |
We're gonna get to the bottom turtle.
link |
so it got to be a real,
link |
I mean, it's a really puzzling thing
link |
why the laws should have this very odd property
link |
that we don't need.
link |
And in fact, it's kind of an embarrassment
link |
in addressing empirical reality.
link |
But it seemed to be almost,
link |
it seemed to be exactly true for a long time.
link |
And then almost true.
link |
And in way, almost true is even,
link |
is more disturbing than exactly true
link |
because exactly true,
link |
it could have been just a fundamental feature of the world.
link |
And at some level you just have to take it as it is.
link |
And if it's a beautiful, easily articulatable regularity,
link |
you could say that, okay,
link |
that's fine as a fundamental law of nature.
link |
But to say that it's approximately true,
link |
but not exactly, that's weird.
link |
So, and then, so there was great progress
link |
in the late part of the 20th century
link |
in getting to an understanding
link |
of fundamental interactions in general
link |
that shed light on this issue.
link |
It turns out that the basic principles of relativity
link |
and quantum mechanics,
link |
plus the kind of high degree of symmetry that we found,
link |
the so called gauge symmetry
link |
that characterizes the fundamental interactions,
link |
when you put all that together,
link |
it's a very, very constraining framework.
link |
And it has some indirect consequences
link |
because the possible interactions are so constrained.
link |
And one of the indirect consequences
link |
is that the possibilities for violating the symmetry
link |
between forwards and backwards in time are very limited.
link |
They're basically only two.
link |
And one of them occurs and leads to a very rich theory
link |
that explains the Cronin Fish experiment
link |
and a lot of things that have been done subsequently
link |
has been used to make all kinds of successful predictions.
link |
So that's turned out to be a very rich interaction.
link |
It's esoteric and the effects only show up at accelerators
link |
and are small and so on,
link |
but they might've been very important in the early universe
link |
and lead to them be connected to the asymmetry
link |
between matter and antimatter in the present universe.
link |
And so, but that's another digression.
link |
The point is that that was fine.
link |
That was a triumph to say
link |
that there was one possible kind of interaction
link |
that would violate time reversal symmetry.
link |
And sure enough, there it is.
link |
But the other kind doesn't occur.
link |
So we still got a problem.
link |
Why doesn't it occur?
link |
So we're close to really finally understanding
link |
this profound gratuitous feature of the world
link |
that is almost but not quite symmetric
link |
under reversing the direction of time, but not quite there.
link |
And to understand that last bit
link |
is a challenging frontier of physics today.
link |
And we have a promising proposal for how it works,
link |
which is a kind of theory of evolution.
link |
So there's this possible interaction,
link |
which we call a coupling,
link |
and there's a numerical quantity
link |
that tells us how strong that is.
link |
And traditionally in physics,
link |
we think of these kinds of numerical quantities
link |
as constants of nature that you just have to put them in.
link |
From experiment, they have a certain value and that's it.
link |
And who am I to question what God doing?
link |
They're just constant.
link |
Well, they seem to be just constants.
link |
I'm just wondering.
link |
it's been fruitful to think and work out a theory
link |
where that strength of interaction
link |
is actually not a constant.
link |
It's a fun, it's a field.
link |
It's a, fields are the fundamental ingredients
link |
of modern physics.
link |
Like there's an electron field,
link |
there's a photon field,
link |
which is also called the electromagnetic field.
link |
And so all of these particles
link |
are manifestations of different fields.
link |
And there could be a field,
link |
something that depends on space and time.
link |
So a dynamical entity instead of just a constant here.
link |
And if you do things in a nice way,
link |
that's very symmetric,
link |
very much suggested aesthetically by the theory.
link |
But the theory we do have,
link |
then you find that you get a field
link |
which as it evolves from the early universe,
link |
settles down to a value
link |
that's just right to make the laws
link |
very nearly exact, invariant or symmetric
link |
with respect to reversal of time.
link |
It might appear as a constant,
link |
but it's actually a field that evolved over time.
link |
It evolved over time, okay.
link |
But when you examine this proposal in detail,
link |
you find that it hasn't quite settled down to exactly zero.
link |
the field is still moving around a little bit.
link |
And because the motion is so,
link |
the motion is so difficult.
link |
The material is so rigid.
link |
And this material,
link |
the field that fills all space is so rigid.
link |
Even small amounts of motion can involve lots of energy.
link |
And that energy takes the form of particles,
link |
fields that are in motion
link |
are always associated with particles.
link |
And those are the axioms.
link |
And if you calculate how much energy
link |
is in these residual oscillations,
link |
this axiom gas that fills all the universe,
link |
if this fundamental theory is correct,
link |
you get just the right amount
link |
to make the dark matter that astronomers want.
link |
And it has just the right properties.
link |
So I'd love to believe that.
link |
So that might be a thing that unlocks,
link |
might be the key to understanding dark matter.
link |
Yeah, I'd like to think so.
link |
And many, many physicists are coming around
link |
to this point of view,
link |
which I've been a voice in the wilderness.
link |
I was a voice in the wilderness for a long time,
link |
but now it's become very popular, maybe even dominant.
link |
so this axion particle slash field
link |
would be the thing that explains dark matter.
link |
It explains, yeah,
link |
would solve this fundamental question of finally,
link |
of why the laws are almost, but not quite exactly the same
link |
if you run them backwards in time.
link |
And then seemingly in a totally different
link |
conceptual universe,
link |
it would also provide,
link |
give us an understanding of the dark matter.
link |
That's not what it was designed for.
link |
And the theory wasn't proposed with that in mind,
link |
but when you work out the equations, that's what you get.
link |
That's always a good sign.
link |
I think I vaguely read somewhere
link |
that there may be early experimental validation of axion.
link |
Is that, am I reading the wrong?
link |
Well, there've been quite a few false alarms
link |
and I think there are some of them still,
link |
people desperately wanna find this thing.
link |
And, but I don't think any of them are convincing
link |
but there are very ambitious experiments
link |
you have to design new kinds of antennas
link |
that are capable of detecting these predicted particles.
link |
And it's very difficult.
link |
They interact very, very weakly.
link |
If it were easy, it would have been done already.
link |
But I think there's good hope
link |
that we can get down to the required sensitivity
link |
and actually test whether these ideas are right
link |
in coming years or maybe decades.
link |
And then understand one of the big mysteries,
link |
like literally big in terms of its fraction
link |
of the universe is dark matter.
link |
Let me ask you about, you mentioned a few times,
link |
These things are, it's a very beautiful idea
link |
when we start to treat space and time
link |
as similar frameworks.
link |
Physical phenomena.
link |
Right, that's what motivated it.
link |
First of all, what are crystals?
link |
And what are time crystals?
link |
Okay, so crystals are orderly arrangements
link |
of atoms in space.
link |
And many materials,
link |
if you cool them down gently, will form crystals.
link |
And so we say that that's a state of matter
link |
that forms spontaneously.
link |
And an important feature of that state of matter
link |
is that the end result, the crystal,
link |
has less symmetry than the equations
link |
that give rise to the crystal.
link |
So the equations, the basic equations of physics
link |
are the same if you move a little bit.
link |
So you can move, they're homogeneous,
link |
but crystals aren't.
link |
The atoms are in particular place,
link |
so they have less symmetry.
link |
And time crystals are the same thing in time, basically.
link |
But of course, so it's not positions of atoms,
link |
but it's orderly behavior that certain states of matter
link |
will arrange themselves into spontaneously
link |
if you treat them gently
link |
and let them do what they want to do.
link |
But repeat in that same way indefinitely.
link |
That's the crystalline form.
link |
You can also have time liquids,
link |
or you can have all kinds of other states of matter.
link |
You can also have space time crystals
link |
where the pattern only repeats if with each step of time,
link |
you also move at a certain direction in space.
link |
So yeah, basically it's states of matter
link |
that displace structure in time spontaneously.
link |
So here's the difference.
link |
When it happens in time,
link |
it sure looks a lot like it's motion,
link |
and if it repeats indefinitely,
link |
it sure looks a lot like perpetual motion.
link |
Like looks like free lunch.
link |
And I was told that there's no such thing as free lunch.
link |
Does this violate laws of thermodynamics?
link |
No, but it requires a critical examination
link |
of the laws of thermodynamics.
link |
I mean, let me say on background
link |
that the laws of thermodynamics
link |
are not fundamental laws of physics.
link |
There are things we prove
link |
under certain circumstances emerge
link |
from the fundamental laws of physics.
link |
They're not, we don't posit them separately.
link |
They're meant to be deduced,
link |
and they can be deduced under limited circumstances,
link |
but not necessarily universally.
link |
And we're finding some of the subtleties
link |
and sort of accept edge cases
link |
where they don't apply in a straightforward way.
link |
So time crystals do obey,
link |
do have this structure in time,
link |
but it's not a free lunch
link |
because although in a sense, things are moving,
link |
they're already doing what they want to do.
link |
so if you want to extract energy from it,
link |
you're gonna be foiled
link |
because there's no spare energy there.
link |
So you can add energy to it and kind of disturb it,
link |
but you can't extract energy from this motion
link |
because it's gonna, it wants to do,
link |
that's the lowest energy configuration that there is,
link |
so you can't get further energy out of it.
link |
So in theory, I guess perpetual motion,
link |
you would be able to extract energy from it
link |
if such a thing was to be created,
link |
you can then milk it for energy.
link |
Well, what's usually meant
link |
in the literature of perpetual motion
link |
is a kind of macroscopic motion
link |
that you could extract energy from
link |
and somehow it would crank back up.
link |
That's not the case here.
link |
If you want to extract energy,
link |
this motion is not something you can extract energy from.
link |
If you intervene in the behavior,
link |
you can change it, but only by injecting energy,
link |
not by taking away energy.
link |
You mentioned that a theory of everything
link |
may be quite difficult to come by.
link |
A theory of everything broadly defined
link |
meaning like truly a theory of everything,
link |
but let's look at a more narrow theory of everything,
link |
which is the way it's used often in physics
link |
is a theory that unifies our current laws of physics,
link |
general relativity, quantum field theory.
link |
Do you have thoughts on this dream
link |
of a theory of everything in physics?
link |
Is there any promising ideas out there in your view?
link |
Well, it would be nice to have.
link |
It would be aesthetically pleasing.
link |
Will it be useful?
link |
Well, I shouldn't, it's dangerous to say that,
link |
I think we, certainly not in the foreseeable future.
link |
Maybe to understand black holes.
link |
Yeah, but that's, yes, maybe to understand black holes,
link |
but that's not useful.
link |
And well, not only, I mean,
link |
to understand it's worse,
link |
it's not useful in the sense
link |
that we're not gonna be basing any technology anytime soon
link |
on black holes, but it's more severe than that,
link |
I would say it's that the kinds of questions
link |
about black holes that we can't answer
link |
within the framework of existing theory
link |
are ones that are not going to be susceptible
link |
to astronomical observation in the foreseeable future.
link |
They're questions about very, very small black holes
link |
when quantum effects come into play
link |
so that black holes are,
link |
not black holes, they're emitting this discovery
link |
of Hawking called Hawking radiation,
link |
which for astronomical black holes is a tiny, tiny effect
link |
that no one has ever observed, it's a prediction
link |
that's never been checked.
link |
So like supermassive black holes, that doesn't apply?
link |
No, no, the predicted rate of radiation
link |
from those black holes is so tiny
link |
that it's absolutely unobservable
link |
and is overwhelmed by all kinds of other effects.
link |
So it's not practical in the sense of technology,
link |
it's not even practical in the sense
link |
of application to astronomy, our existing theory
link |
of general relativity and quantum theory
link |
and our theory of the different fundamental forces
link |
is perfectly adequate to all problems of technology,
link |
of technology, for sure, and almost all problems
link |
of astrophysics and cosmology that appear
link |
except with the notable exception
link |
of the extremely early universe, if you want to ask,
link |
what happened before the Big Bang
link |
or what happened right at the Big Bang,
link |
which would be a great thing to understand, of course.
link |
Yes. We don't, but.
link |
But what about the engineering question?
link |
So if we look at space travel,
link |
so I think you've spoken with him, Eric Weinstein.
link |
Oh, yeah. Really, you know,
link |
he says things like we want to get off this planet.
link |
His intuition is almost motivated
link |
for the engineering project of space exploration
link |
in order for us to crack this problem
link |
of becoming a multi planetary species,
link |
we have to solve the physics problem.
link |
His intuition is like, if we figure out this,
link |
what he calls the source code, which is like,
link |
like a theory of everything might give us clues
link |
on how to start hacking the fabric of reality,
link |
like getting shortcuts, right?
link |
It might. I can't say that, you know,
link |
I can't say that it won't,
link |
but I can say that in the 1970s and early 1980s,
link |
we achieved huge steps in understanding matter.
link |
QCD, much better understanding of the weak interaction,
link |
much better understanding of quantum mechanics in general.
link |
And it's had minimal impact on technology.
link |
On rocket design, on propulsion.
link |
On rocket design, on anything, any technology whatsoever.
link |
And now we're talking about much more esoteric things.
link |
And since I don't know what they are,
link |
I can't say for sure that they won't affect technology,
link |
but I'm very, very skeptical
link |
that they would affect technology.
link |
Because, you know, to access them,
link |
you need very exotic circumstances
link |
to make new kinds of particles with high energy.
link |
You need accelerators that are very expensive
link |
and you don't produce many of them, and so forth.
link |
You know, it's just, it's a pipe dream, I think.
link |
Yeah, about space exploration.
link |
I'm not sure exactly what he has in mind,
link |
but to me, it's more a problem of,
link |
I don't know, something between biology and...
link |
And information processing.
link |
Processing, what you mean, how should I...
link |
I think human bodies are not well adapted to space.
link |
Even Mars, which is the closest thing
link |
to a kind of human environment
link |
that we're gonna find anywhere close by.
link |
Very, very difficult to maintain humans on Mars.
link |
And it's gonna be very expensive and very unstable.
link |
But I think, however, if we take a broader view
link |
of what it means to bring human civilization
link |
outside of the Earth, if we're satisfied
link |
with sending mines out there that we can converse with
link |
and actuators that we can manipulate
link |
and sensors that we can get feedback from,
link |
I think that's where it's at.
link |
And I think that's so much more realistic.
link |
And I think that's the long term future
link |
of space exploration.
link |
It's not hauling human bodies all over the place.
link |
That's just silly.
link |
It's possible that human bodies...
link |
So like you said, it's a biology problem.
link |
What's possible is that we extend human life span
link |
in some way, we have to look at a bigger picture.
link |
It could be just like you're saying,
link |
by sending robots with actuators
link |
and kind of extending our limbs.
link |
But it could also be extending some aspect of our minds,
link |
some information, all those kinds of things.
link |
And it could be cyborgs, it could be, it could be...
link |
No, we're talking, not getting the fun.
link |
It could be, you know, it could be human brains
link |
or cells that realize something
link |
like human brain architecture
link |
within artificial environments,
link |
you know, shells, if you like,
link |
that are more adapted to the conditions of space.
link |
And that, yeah, so that's entirely man machine hybrids,
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as well as sort of remote outposts
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that we can communicate with.
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I think those will happen.
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Yeah, to me, there's some sense in which,
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as opposed to understanding the physics
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of the fundamental fabric of the universe,
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I think getting to the physics of life,
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the physics of intelligence,
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the physics of consciousness will,
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the physics of information that brings,
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from which life emerges,
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that will allow us to do space exploration.
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Yeah, well, I think physics in the larger sense
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has a lot to contribute here.
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Not the physics of finding fundamental new laws
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in the sense of another quark or axions even.
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But physics in the sense of,
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physics has a lot of experience
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in analyzing complex situations
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and analyzing new states of matter
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and devising new kinds of instruments
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that do clever things.
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Physics in that sense has enormous amounts
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to contribute to this kind of endeavor.
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But I don't think that looking
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for a so called theory of everything
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has much to do with it at all.
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What advice would you give to a young person today
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with a bit of fire in their eyes,
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high school student, college student,
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thinking about what to do with their life,
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maybe advice about career or bigger advice
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about life in general?
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Well, first read fundamentals
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because there I've tried to give some coherent deep advice.
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That's fundamentals, 10 keys to reality by Frank Kulczyk.
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So that's a good place to start.
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Available everywhere.
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If you wanna learn what I can tell you.
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Is there an audio book?
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I read that ebook.
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Yes, there is an audio book.
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There's an audio book, that's awesome.
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I think it's, I can give three pieces of wise advice
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that I think are generally applicable.
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One is to cast a wide net,
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to really look around and see what looks promising,
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what catches your imagination and promising.
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Yeah, and those, you have to balance those two things.
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You could have things that catch your imagination,
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but don't look promising in the sense
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that the questions aren't ripe or,
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and things that you,
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and part of what makes things attractive is that,
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whether you thought you liked them or not,
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is if you can see that there's ferment
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and new ideas coming up that become,
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that's attractive in itself.
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So when I started out, I thought I was,
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and when I was an undergraduate,
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I intended to study philosophy
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or questions of how mind emerges from matter.
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But I thought that that wasn't really right.
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Timing isn't right yet.
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The right, the timing wasn't right
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for the kind of mathematical thinking
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and 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.
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And that's a pretty easy thing to do today
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because of the internet.
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You can look at all kinds of things.
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You have to be careful though
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because there's a lot of crap also.
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But you can sort of tell the difference
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if you do a little digging.
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So don't settle on just,
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what your thesis advisor tells you to do
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or what your teacher tells you to do.
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Look for yourself and get a sense of what seems promising,
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not what seemed promising 10 years ago or, so that's one.
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Another thing is to, is kind of complimentary to that.
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Well, they're all complimentary.
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Complimentary to that is to read history
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and read the masters,
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the history of ideas and masters of ideas.
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I'd benefited enormously from, as early in my career,
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from reading in physics, Einstein in the original
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and Feynman's lectures as they were coming out and Darwin.
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You know, these, you can learn what it, and Galileo,
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you can learn what it is to wrestle with difficult ideas
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and how great minds did that.
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You can learn a lot about style,
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how to write your ideas up and express them in clear ways.
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And also just a couple of that with,
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I also enjoy reading biographies.
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And biographies, yes, similarly, right, yeah.
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So it gives you the context of the human being
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that created those ideas.
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Right, and brings it down to earth in the sense that,
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you know, it was really human beings who did this.
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It's not, and they made mistakes.
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And yeah, I also got inspiration from Bertrand Russell
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who was a big hero and H.G. Wells and yeah.
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So read the masters, make contact with great minds.
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And when you are sort of narrowing down on a subject,
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learn about the history of the subject
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because that really puts in context
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what you're trying to do and also gives a sense of community
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and grandeur to the whole enterprise.
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And then the third piece of advice
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is complimentary to both those,
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which is sort of to get the basics under control
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as soon as possible.
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So if you wanna do theoretical work in science,
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you know, you have to learn calculus,
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multivariable calculus, complex variables, group theory.
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Nowadays, you have to be highly computer literate
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if you want to do experimental work.
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You also have to be computer literate
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and you have to learn about electronics
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and optics and instruments.
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So get that under control as soon as possible
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because it's like learning a language to produce great works
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and express yourself fluently and with confidence.
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It should be your native language.
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These things should be like your native language.
link |
So you're not wondering what is the derivative?
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This is just part of your, it's in your bones,
link |
so to speak, and the sooner that you can do that,
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So all those things can be done in parallel and should be.
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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.
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Do you think about your mortality?
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Are you afraid of death?
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Well, afraid is the wrong word.
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I mean, I wish it weren't going to happen
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and I'd like to, but.
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Do you think about it?
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I, you know, occasionally I think about,
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well, I think about it very operationally
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in the sense that there's always a trade off
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between exploration and exploitation.
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This is a classic subject in computer science,
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actually in machine learning that when you're
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in an unusual circumstance, you want to explore
link |
to see what the landscape is and what, and gather data.
link |
But then at some point you want to use that,
link |
make, decide, make choices and say,
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this is what I'm going to do and exploit the knowledge
link |
you've accumulated.
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And the longer the period of exploitation you anticipate,
link |
the more exploration you should do in new directions.
link |
And so for me, I've had to sort of adjust the balance
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of exploration and exploitation and.
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That's it, you've explored quite a lot.
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Yeah, well, I haven't shut off the exploitation at all.
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I'm still hoping for. The exploration.
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The exploration, right.
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I'm still hoping for 10 or 15 years
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of top flight performance.
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But the, several years ago now when I was 50 years old,
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I was at the Institute for Advanced Study
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and my office was right under Freeman Dyson's office
link |
and we were kind of friendly.
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And, you know, he found out it was my 50th birthday
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and said, congratulations.
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And you should feel liberated because no one expects much
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of a 50 year old theoretical physicist.
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And he, and he obviously had felt liberated
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by reaching a certain age.
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And yeah, there is something to that.
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I feel, you know, I feel I don't have to catch,
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I don't have to keep in touch
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with the latest hypertechnical developments
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in particle physics or string theory or something.
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I, because I'm not gonna, I'm really not gonna
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be exploiting that.
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But I, but where I am exploring in these directions
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of machine learning and things like that.
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And, but then, but I'm also concentrating
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within physics on exploiting directions
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that I've already established
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and the laws that we already have
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and doing things like,
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I'm very actively involved in trying to design,
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helping people, experimentalists and engineers even
link |
to design antennas that are capable of detecting axions.
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So there, and that's, there we're deep
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in the exploitation stage.
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It's not a matter of finding the new laws,
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but of really, you know, using the laws we have
link |
to kind of finish the story off.
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So it's complicated, but I'm, you know,
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I'm very happy with my life right now
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and I'm enjoying it and I don't wanna cloud that
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by thinking too much that it's gonna come to an end.
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You know, it's a gift I didn't earn.
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Is there a good thing to say about
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why this gift that you've gotten
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and didn't deserve is so damn enjoyable?
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So like, what's the meaning of this thing, of life?
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To me, interacting with people I love, my family,
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and I have a very wide circle of friends now
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and I'm trying to produce some institutions
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that will survive me as well as my work
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and it's just, it's, how should I say?
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It's a positive feedback loop when you do something
link |
and people appreciate it and then you wanna do more
link |
and you get rewarded and it's just, how should I say?
link |
This is another gift that I didn't earn
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and don't understand, but I have a dopamine system
link |
and yeah, I'm happy to use it.
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It seems to get energized by the creative process,
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by the process of exploration.
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And all of that started from the little fluctuations
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shortly after the Big Bang.
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Frank, well, whatever those initial conditions
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and fluctuations did that created you, I'm glad they did.
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This is, thank you for all the work you've done,
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for the many people you've inspired,
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for the many, of the billion, most of your ideas
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were pretty useless of the several billions,
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as it is for all humans, but you had quite a few
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truly special ideas and thank you for bringing those
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to the world and thank you for wasting your valuable time
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with me today, it's truly an honor.
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It's been a joy and I hope people enjoy it
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and I think the kind of mind expansion that I've enjoyed
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by interacting with physical reality at this deep level,
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I think can be conveyed to and enjoyed by many, many people
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and that's one of my missions in life, to share it.
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Thanks for listening to this conversation
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with Frank Wilczek and thank you to The Information,
link |
NatSuite, ExpressVPN, Blinkist and 8sleep.
link |
Check them out in the description to support this podcast
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and now let me leave you with some words
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from Albert Einstein, nothing happens until something moves.
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Thanks for listening and hope to see you next time.