Speaker 1: Hey, Daniel, did you guys figure out quantum gravity yet?
Speaker 1: Not yet? How about a dark matter Nope, still working
Speaker 1: on it. Dark energy not that one either, Quantum wave
Speaker 1: function collapse we got nava. Oh. Man, We've been doing
Speaker 1: this podcast for years now, man, talking about these mysteries,
Speaker 1: and you've made no progress. What's going on? Maybe the
Speaker 1: problem is I've been spending a lot of time on
Speaker 1: the podcast, or maybe you just need a new idea,
Speaker 1: like another podcast. Yeah, Daniel, Jorge actually solves the mysteries
Speaker 1: of the universe instead of just talking about it. We
Speaker 1: could just put a microphone in your office, maybe the
Speaker 1: sound of Daniel napping. Hi. I'm Orge. I'm a cartoonist
Speaker 1: and the creator of PhD comics. Hi I'm Daniel. I'm
Speaker 1: a particle physicist and a professor UC Irvine, and I'm
Speaker 1: totally ready to take to the streets for the next
Speaker 1: scientific revolution. What do you mean, take to the threets
Speaker 1: to protest or to celebrate? I don't know. That's just
Speaker 1: how revolutions start, right, Everybody runs into the streets and
Speaker 1: raises a stick and yells, and boom, the government just
Speaker 1: falls over. Isn't that what happens? Oh? I see. You
Speaker 1: want to promote a revolution, you need to put up
Speaker 1: like barricades and streets with equations. I guess that's right. Everybody,
Speaker 1: grab a piece of chalk. We're gonna do physics on
Speaker 1: the street. Literally. And then who are we claiming independence from?
Speaker 1: Or who are we overturning big physics? Man? Of course?
Speaker 1: Oh is that like the big lobby or good physics
Speaker 1: or or bad physics. I'm really confused about this revolutionary idea.
Speaker 1: It's a bunch of physicists in the back room. Instead
Speaker 1: of smoking cigars though, they're just napping around a bunch
Speaker 1: of chalkboards. Oh and you want to overthrow them and
Speaker 1: put them to the guillotine theoretically speaking, yes, intellectual guillotine exactly,
Speaker 1: the intellectual gailloty. Oh boy, heads will roll in your head,
Speaker 1: but yeah. Welcome to our podcast Daniel and Jorge Explain
Speaker 1: the Universe, a production of I Heart Radio in which
Speaker 1: heads roll and minds are blown. When we talk about
Speaker 1: the crazy ideas of the universe. We know that our
Speaker 1: current theories of the universe must be wrong. They are
Speaker 1: definitely incomplete. They cannot describe nature correctly, and we join
Speaker 1: you in a search for those new ideas, probing ever
Speaker 1: deeper into the very nature of space and time and
Speaker 1: the universe, what this reality is around us, asking questions
Speaker 1: about the very basic nature of consciousness and measurement and information,
Speaker 1: and just trying to figure it all out. Man. Yeah,
Speaker 1: because it is a pretty crazy universe full of amazing
Speaker 1: things to discover and find out, and we're just puny,
Speaker 1: little tiny beings on this floating rock in space trying
Speaker 1: to figure out how it all works. It's sort of
Speaker 1: like we are solving the biggest detective mystery in the universe,
Speaker 1: because the whole universe is a big mystery for us
Speaker 1: to unravel. And over thousands of years, we've been slowly
Speaker 1: putting together a few ideas about how this bit works
Speaker 1: and how that bit works. And sometimes those ideas even
Speaker 1: fit together to make a bigger, clearer idea, and we
Speaker 1: get these flashes of insight that tell us how the
Speaker 1: universe works. Yeah, because we don't just live in the universe.
Speaker 1: We also wonder about it and we want to figure
Speaker 1: out how it works. Because sometimes it's very useful information, right,
Speaker 1: it depends on who has that information. It can be useful,
Speaker 1: it can be dangerous, but it is absolutely enticing to me.
Speaker 1: It's all about knowing the way the universe works, revealing
Speaker 1: that truth, peeling back those layers of reality to see
Speaker 1: its inner mechanisms. And we've done it pretty good over
Speaker 1: the year, as the centuries. Now that science has been
Speaker 1: going on, and we have some pretty good theories about
Speaker 1: how things work, and let us build amazing structures and
Speaker 1: machines and send things to space and back. But we
Speaker 1: are not quite theory in terms of understanding the very
Speaker 1: small details of how the universe works, especially at the extremes. Yeah,
Speaker 1: you might be forgiven for thinking that physics has it
Speaker 1: mostly figured out. You know, we've developed incredible technologies. We
Speaker 1: have revealed a lot about the way the universe works,
Speaker 1: but we've also revealed how little we know. There's so
Speaker 1: much of the universe that we haven't even begun to describe,
Speaker 1: the dark matter, the dark energy, and enormous open questions
Speaker 1: about the part of the universe that we can describe.
Speaker 1: We don't understand a lot of the fundamental forces. We
Speaker 1: can't bring together gravity and quantum mechanics. There are all
Speaker 1: sorts of things where physics has hit some sort of
Speaker 1: a roadblock. Yeah, so where would you put our estimate,
Speaker 1: would you say that we understand about the three percent
Speaker 1: of the universe? Now, is that what you mean by
Speaker 1: mostly understand the universe about three percent? Because we don't
Speaker 1: understand the full five percent of what we're made out of,
Speaker 1: and there's like ninety five percent of the universe we
Speaker 1: don't know anything about. Yeah, I would generously assess our
Speaker 1: understanding the universe at zero point zero zero zero zero
Speaker 1: one percent, And that's rounding up what from zero hang
Speaker 1: out from? Wow, So you think out of the five
Speaker 1: percent of the universe that is made out of, you know,
Speaker 1: atoms and fonted particles, you think we understand about zero
Speaker 1: point zero zero one percent of it. Yeah. I think
Speaker 1: we are very primitive in our understanding of the nature
Speaker 1: of reality. I think people will look back at our
Speaker 1: ideas in a thousand years and they will chuckle. You know,
Speaker 1: they will look down their nose at us, because our
Speaker 1: ideas are so simple and so ridiculous, the way we
Speaker 1: look back at the Greeks or even further back, you know,
Speaker 1: at cave many cave women their perspective on the universe.
Speaker 1: We are really just beginning our exploration, and so I
Speaker 1: think we haven't even really had time to develop the
Speaker 1: right ideas or the right way to generate those ideas.
Speaker 1: I mean, we've been asking questions about the universe for
Speaker 1: thousands of years, but we've only had a strategy for
Speaker 1: building knowledge, this empirical scientific method for a few hundred years,
Speaker 1: and you know, the mathematics to undergird it is much
Speaker 1: more recent. So we're really just getting started. You know,
Speaker 1: it's like we just put our shoes on. We haven't
Speaker 1: even really walked out the door to explore the universe yet.
Speaker 1: The feature scientists are so snobby. If you cut us
Speaker 1: a break. You know, there's a lot going on right now.
Speaker 1: You know, it's a lot of good stuff on Netflix,
Speaker 1: not even just future scientists, future five year olds. Right
Speaker 1: there will be children's books about the universe in the
Speaker 1: year three thousand that you and I will not understand.
Speaker 1: We would read them and go, what, that's crazy, that
Speaker 1: can't possibly be true. That's wild. So those five year
Speaker 1: olds give a seminar at like M. I. T. And
Speaker 1: all of the famous physicists would go and probably be clueless. Yes,
Speaker 1: it sort of sounds like we are not that far
Speaker 1: along in our knowledge of the universe. Sometimes, but you know,
Speaker 1: there's always hope, and maybe there's always a sort of
Speaker 1: a revolution in theoretical physics and physical thinking, maybe right
Speaker 1: around the corner. You never know, right, You never do know.
Speaker 1: And when we look back at the development of ideas,
Speaker 1: they seem sort of linear, you know, like Sally figured
Speaker 1: out this, and then Alicia figured out that, and then
Speaker 1: Bob came along and put this cherry on top and
Speaker 1: tied it together and took credit for all of it,
Speaker 1: and this kind of stuff. It seems sort of linear,
Speaker 1: But when you're in the middle of it, it it feels
Speaker 1: much more like a huge cloud of confusion. There are
Speaker 1: people going in all sorts of directions, and nobody knows
Speaker 1: which one is going to be the foundation of future
Speaker 1: brilliance and which one is totally a dead end. And
Speaker 1: so it's really hard to tell in the moment what
Speaker 1: the path of future physics is. Yeah, it could be
Speaker 1: that the idea that changes everything or solves everything is
Speaker 1: out there right now in the mind of a physicist,
Speaker 1: but then maybe nobody takes him or her seriously. Yeah,
Speaker 1: it certainly could be. And it also could be that
Speaker 1: there's been a new development of a kind of mathematics
Speaker 1: that was developed just because it's math and it's fun,
Speaker 1: and then in ten years some physicists will figure out
Speaker 1: how to use it to solve some deep problem in physics.
Speaker 1: We've seen that happen a bunch of times. You know,
Speaker 1: field theory and group theory, all these things were developed
Speaker 1: not for physics, but then we're later applied to physics
Speaker 1: and have become incredibly useful. So you never really know
Speaker 1: when sort of like the pieces of the puzzle are
Speaker 1: going to find each other and click together to really
Speaker 1: give us that glimpse of the next generation of ideas.
Speaker 1: So today on the podcast, we'll be asking the question,
Speaker 1: are we witnessing a revolution in theoretical physics? You mean,
Speaker 1: like it's happening right now. We could be witnessing it.
Speaker 1: We just don't know it. Yeah, we could be living
Speaker 1: in the middle of it right now. Exactly. There are
Speaker 1: some crazy new ideas that have been developed in the
Speaker 1: last few years that suggests an entirely new way to
Speaker 1: try to attack these questions of the fundamental nature of
Speaker 1: the universe. And we don't know if this is a
Speaker 1: dead end which will be added to the dust bin
Speaker 1: of dead ends, or if you know, it will be
Speaker 1: seen later as a critical turning point in the history
Speaker 1: of physics. M Yeah, it's interesting because you know, if
Speaker 1: you look back at the history of science, it does
Speaker 1: seem like sometimes we think we figured everything out, but
Speaker 1: then the more we look into it, the more we
Speaker 1: realize that our theories don't work. You know, like Newtonian physics,
Speaker 1: we thought we had unlocked, you know, the secrets of
Speaker 1: the universe, but then eventually we found that it doesn't
Speaker 1: work all of the time. And then we came up
Speaker 1: with quantum theory, and we thought we had solved the
Speaker 1: mysteries then, but then it turns out it doesn't quite
Speaker 1: work all of the time. Yeah, exactly. That's why the
Speaker 1: more we know, the more we realize we know less
Speaker 1: and less, Which is why I was trying to really
Speaker 1: hard to be conservative in giving an estimate of our
Speaker 1: fraction of the universe that we have understood, because frankly,
Speaker 1: it seems to just drop as time goes on. Well,
Speaker 1: I guess maybe when you give such a low estimate,
Speaker 1: what you really mean is that maybe the theories we
Speaker 1: have now are you know, they work for most of
Speaker 1: the time, and for most of the cases that we
Speaker 1: sort of are in, you know, here on Earth sending
Speaker 1: things to space. It works pretty well. But I think
Speaker 1: maybe what you're thinking about is that maybe it's's like
Speaker 1: fundamentally wrong, like there's something wrong with its very foundation. Yeah,
Speaker 1: it could just be the wrong way to attack the problem.
Speaker 1: And sometimes the wrong approach works for a while and
Speaker 1: then you get stuck. You know. For example, Aristotle and
Speaker 1: Plato and those folks, they made a lot of progress
Speaker 1: in understanding the nature of life and experience and consciousness
Speaker 1: and you know, laid the foundations of philosophy. But it
Speaker 1: wasn't until Galileo and folks in the fire or so
Speaker 1: realize that it's important to actually go out and do experiments,
Speaker 1: to make measurements, to ask the universe questions. This branch
Speaker 1: of science we now call experimentation was a vital contribution
Speaker 1: to like building knowledge and adding to our machine to
Speaker 1: systematically build more knowledge. So sometimes we don't just make
Speaker 1: progress in the ideas, but in the ideas for how
Speaker 1: to make new ideas, and that can reveal something fundamentally
Speaker 1: new about the nature of the universe. M Yeah, I
Speaker 1: guess it's kind of a philosophical thing, you know, like
Speaker 1: if you have a theory that works ninety five percent
Speaker 1: of the time, but it's fundamentally incorrect. Is it still
Speaker 1: a good theory or not? You know, like our current
Speaker 1: theories allow us to send things to Mars and to
Speaker 1: maniplate atoms and things like that, And so I would
Speaker 1: say as an engineer, that's pretty good. You know, we're
Speaker 1: like nine of the way they're you know, we're not
Speaker 1: going into a black hole anytime soon, or you know,
Speaker 1: going faster than the speed of light anytime soon. And
Speaker 1: so I would say we've done pretty good. But maybe
Speaker 1: as a theoretical physicist, you might be thinking, like, what
Speaker 1: if it's all fundamentally wrong, that means we're zero percent right. Yeah,
Speaker 1: And it depends on the question you're asking. It depends
Speaker 1: on what your goal is. If your goal is to
Speaker 1: send something to Mars, then you don't really need to
Speaker 1: understand quantum gravity and the deep fundamental nature of space time.
Speaker 1: But if those are your motivating questions, if the reason
Speaker 1: you get out of bed and the thing that pulls
Speaker 1: you through life is this desire to understand the universe
Speaker 1: at its most basic level, and it's fundamental, foundational level,
Speaker 1: the essential ingredients that make it what it is, then
Speaker 1: you're not satisfied with like an approximate version that mostly works,
Speaker 1: because the theory we have today it does mostly work
Speaker 1: for the kinds of experiments we can do. We also
Speaker 1: know that absolutely cannot be the real theory of the universe,
Speaker 1: the one that describes, you know, the very first few
Speaker 1: moments and the crazy situation of very high energy and
Speaker 1: high density. It can't describe what happens when space and
Speaker 1: time distort very dramatically. It just fails, it breaks down,
Speaker 1: and so it can't be the real story of the universe.
Speaker 1: It can still be very very useful, the way Newtonian
Speaker 1: physics is much more useful than Einsteinian physics to like
Speaker 1: calculate the trajectory of a baseball, right, It could still
Speaker 1: be very helpful and very effective. It's just not the
Speaker 1: fundamental story. So that's what wakes you up in the morning,
Speaker 1: gets you out of bed. But then what makes you
Speaker 1: when I get taken napp then the same thing because
Speaker 1: it's exhausting to think about. So we might be witnessing
Speaker 1: a revolution in theoretical physics, and in particular we're going
Speaker 1: to talk about a special kind of theory or a
Speaker 1: special theory that it's a pretty good candidate for maybe
Speaker 1: overtaking or overturning everything we know about physics. Right, that's right,
Speaker 1: And this is not necessarily a new idea about what
Speaker 1: the universe is as much as a new method to
Speaker 1: try to find new ideas. It's like adding experiments to
Speaker 1: your strategy for figuring out the universe. This is like, well,
Speaker 1: let's take a new approach to finding new ideas about
Speaker 1: the universe. Let's add to the scientific method. Let's give
Speaker 1: it a tweak, and maybe that will reveal new ideas
Speaker 1: we've overlooked before. It's like a meta theory, like how
Speaker 1: to make theories theory interesting. But it's not control by
Speaker 1: Mark Zuckerberg, thankfully, and it's real you can actually maybe
Speaker 1: touch it. So we have this meta theory, this theory
Speaker 1: of theories called constructor theory. That's the name of it. Yeah,
Speaker 1: it's called the constructor theory. And it was developed by
Speaker 1: a couple of folks at Oxford. One of them is
Speaker 1: David Deutsch, and he's famous for doing like quantum information theory.
Speaker 1: He's an expert in quantum computing and he's had sort
Speaker 1: of the inspiration for this idea a while ago. And
Speaker 1: then a grad student worked with him. Her name is
Speaker 1: Kiara Marletto. She really elaborated it and tried to make
Speaker 1: a concrete and try to turn it into something. And
Speaker 1: together they've been developing this constructor theory for a few
Speaker 1: years now and it's got quite a few converts and
Speaker 1: lots of our listeners have written in and said, what
Speaker 1: is this thing? Can you please explain it to us? Yeah,
Speaker 1: because it's it sounds interesting. It sort of sounds sort
Speaker 1: of like a toy from my childhood, like a construction
Speaker 1: toy maybe like you get different pieces and you can
Speaker 1: build them together, or like a transformer. I think there's
Speaker 1: something called constructor cons Well, you know, they do have
Speaker 1: transformations in constructor theory, so maybe you're on the right track.
Speaker 1: Maybe they'll develop, you know, tinker toys. Also maybe watch
Speaker 1: the same shows. So yeah, this is a new theory
Speaker 1: of theories. And so, as usual, we were wondering how
Speaker 1: many people out there had heard of this or had
Speaker 1: an idea of what it could be. So Daniel went
Speaker 1: out there into the internet to ask people what is
Speaker 1: constructor theory? So thanks to everybody who was a willing
Speaker 1: participant in this fun game of answer A tough physics
Speaker 1: question without any preparation. If you'd like to participate, please
Speaker 1: don't be shy. If you've been listening for a while
Speaker 1: and never dipped your toes in, now is the time
Speaker 1: right to us two questions at Daniel and Jorge dot com.
Speaker 1: So think about it for a second. What would you
Speaker 1: guess is constructor theory. Here's what people have to say.
Speaker 1: I know that it is linked with physics, but I
Speaker 1: don't know this time what it's about. I haven't heard
Speaker 1: of constructor theory before, but I'm guessing it has to
Speaker 1: do with an idea of how either things on a
Speaker 1: very tiny scale or a very large scale are put together.
Speaker 1: Constructor theory is the theory of how there is, planets,
Speaker 1: and other types of styles have been created by ancient aliens,
Speaker 1: maybe an alternative to creationism as opposed to the Big
Speaker 1: Bang theory. The assumption is this has something to do
Speaker 1: with a theory that is based upon some form of
Speaker 1: building blocks, meaning that whatever that this constructor theory relates
Speaker 1: to in whatever aspects of physics, this has something to
Speaker 1: do with building upon a base of knowledge, as opposed
Speaker 1: to something groundbreaking and out of left field by the name.
Speaker 1: I would think it's something to do with creation, how
Speaker 1: the universe started, or how we have been created, or
Speaker 1: how just everything being created. Really, I've not heard of
Speaker 1: constructor theory, but it sounds like a theory on how
Speaker 1: the universe was made or constructed. My guess is it
Speaker 1: would be it's to do with building something, So it
Speaker 1: could be to do with putting atoms together or putting
Speaker 1: subtomic particles together to make something bigger. I've never heard
Speaker 1: of the constructor theory, but it does remind me of
Speaker 1: the Bible and God creating everything in seven days, So
Speaker 1: could the constructor theory have anything to do with that?
Speaker 1: I'd say something that has to do with engineering, maybe
Speaker 1: like building things, but I have no idea. Ten points
Speaker 1: to the person who said something about physics, because that's
Speaker 1: true in all situations, right, Any any answer can probably
Speaker 1: be answered by something about physics. Yeah, that's true, and
Speaker 1: especially when it's this podcast, so yeah, of that time,
Speaker 1: or something about bananas that would also work. They'll take
Speaker 1: you that last percentage home. Yeah, somebody said something about
Speaker 1: engineering too, which I technically also applies to all answers. M. Yeah,
Speaker 1: that's true because all engineering, fundamentally is just physics. Yeah,
Speaker 1: and all physics is fundamentally useful only for engineering and knaps.
Speaker 1: Engineering plus naps, that's right, Yeah, making sure that you
Speaker 1: get enough rest. Yes, some people thought it may be
Speaker 1: related to creation, right, constructor, like maybe you're constructing the universe.
Speaker 1: It is a very general sounding term, right, it's a
Speaker 1: little vague, so it doesn't give you a lot to
Speaker 1: really work with. If you haven't heard of it before,
Speaker 1: you probably weren't going to guess what it was just
Speaker 1: from the name. I guess it's interesting because you can
Speaker 1: read it as now and like constructor theory, you know,
Speaker 1: like maybe there's a constructor, like a like a person
Speaker 1: or an entity. We're trying to figure out how it works. Yeah,
Speaker 1: or like who made the universe? Mmm? Oh I see, yeah,
Speaker 1: well that explains why people were talking about God and creation.
Speaker 1: It clicks now, I get it. Yeah, yeah, maybe there
Speaker 1: is a constructor, you know, I see theory of the constructor.
Speaker 1: It's just starting into a conspiracy theory. Whoever the constructor is,
Speaker 1: I hope he took a good nap after he created
Speaker 1: the universe. He or she or it or they. I
Speaker 1: think that's in the pile. Daniel on the Seventh Day
Speaker 1: the constructor took a nap. There you go. See, napping
Speaker 1: is crucial everywhere. That's right, it's a holy concept. Naps
Speaker 1: are sacred. Yeah, so maybe step us through Daniel. What
Speaker 1: is constructor theory? Like, what's the overall idea of it?
Speaker 1: The idea of constructor theory is to take a different
Speaker 1: approach to trying to develop theories of the universe. Now,
Speaker 1: our current approach is pretty good, but it has sort
Speaker 1: of a singular focus. It says, try to figure out
Speaker 1: sort of what's going on in the universe right now,
Speaker 1: and then find the rules for how the universe is
Speaker 1: going to change the dynamics. Like, the universe is like this,
Speaker 1: it's two particles in this configuration. What are the rules
Speaker 1: for how those particles should move and where will they
Speaker 1: be in the future, and so you know, Newtonian physics,
Speaker 1: for example, tells you if you hit a baseball, how
Speaker 1: is it going to fly? What is its path? And
Speaker 1: even quantum mechanics tells you if you have a wave
Speaker 1: function and it hits a potential, well, what's going to happen?
Speaker 1: And so a lot of current physics is what we
Speaker 1: call like initial value problems. It says, here's the current
Speaker 1: situation the universe, how is that going to change? And
Speaker 1: so that's like worked for us pretty well so far,
Speaker 1: but it does have its limitations, you mean, like it's
Speaker 1: it's sort of embedded in the way and the reason
Speaker 1: we do science, right, Like we sort of invented science
Speaker 1: so we could predict the future. And so you're saying,
Speaker 1: right now, physics and science is sort of geared or
Speaker 1: designed or sort of assumes that you want to predict
Speaker 1: what's going to happen in the future. Yeah, exactly, and
Speaker 1: not just that you're going to predict what happens the future.
Speaker 1: But that's all you want to think about, is you
Speaker 1: take this configuration of particles or the universe in its
Speaker 1: current state, and you just want to know what are
Speaker 1: the rules that are going to tell it what's going
Speaker 1: to happen in the future. How is it going to
Speaker 1: evolve from now into the future? Right? So, and it's useful,
Speaker 1: right because if you want to predict what your spaceship
Speaker 1: is going to do when you throw it at the moon,
Speaker 1: or whether your bridge is going to hold, that's kind
Speaker 1: of what science is good for. Right. Yeah, it sounds
Speaker 1: like a great strategy, right because it's it's very effective.
Speaker 1: It helps you solve problems. If you have two particles
Speaker 1: and you shoot them together, then our current laws will
Speaker 1: tell you what's going to happen. And so that seems
Speaker 1: very natural. And like a lot of revolutions in physics,
Speaker 1: they come up against something which seems very intuitive and
Speaker 1: seems like it must be all inclusive, and like, what
Speaker 1: could be missing out of that scenario? What possibly could
Speaker 1: you be overlooking using this approach. But those are also
Speaker 1: the times that you need to be skeptical, when you realize, well,
Speaker 1: maybe we've made some assumption very back in the beginning
Speaker 1: of how we started things, and we could have taken
Speaker 1: another path, We could have started somewhere else, and maybe
Speaker 1: we would have gotten to a different point. It's really
Speaker 1: hard to imagine sort of a different history of physics
Speaker 1: if Newton hadn't been around and somebody else had conceived
Speaker 1: physics in a different way. But that's essentially what we're
Speaker 1: trying to do here is go back to the very
Speaker 1: beginning and ask is there another way to formulate physics
Speaker 1: other than this basic approach of taking the universe and
Speaker 1: trying to write the rules of how it changes? Right?
Speaker 1: Because I think what you're saying, is that where this
Speaker 1: way of approaching it has taken us. It has led
Speaker 1: to a point where we have theories about the universe,
Speaker 1: but they fail at some point, right, like they're they're
Speaker 1: not good all the way. And it could be that
Speaker 1: we do find theories that follow this approach and eventually work.
Speaker 1: Maybe somebody will come up with a theory of quantum
Speaker 1: gravity that follows this sort of initial value problem approach
Speaker 1: and tells us how to treat the inside of black
Speaker 1: holes and what happens when two particles interact gravitationally. Maybe
Speaker 1: somebody will figure that out. So far we've been stuck,
Speaker 1: and so it's just a good idea to broaden your
Speaker 1: bets and to say, hey, let's send a few other people,
Speaker 1: you know, to the other side of the river or
Speaker 1: down another path, and maybe they'll get there sooner. Right,
Speaker 1: it's catapult um, some kind of launching mechanism. So what
Speaker 1: are some of the ways in which our current theories
Speaker 1: have failed and how serious are they? Yeah, well, you know,
Speaker 1: one is just that we haven't solved some big problems.
Speaker 1: But the other is a little bit more subtle but
Speaker 1: really fascinating, and it's that they sort of failed to
Speaker 1: treat some things that have become really important, you know,
Speaker 1: like especially information, some things that turned out to be
Speaker 1: really vital and understanding the universe, like how quantum information
Speaker 1: moves through the universe, how it goes into black holes
Speaker 1: and comes out of it. These things are not really
Speaker 1: well described by our current theories because they're not exactly described.
Speaker 1: There are emergent phenomena, there are things that like arise
Speaker 1: from the lower level laws, but they're not really treated exactly.
Speaker 1: They're more like statistical approximations. For example, if you describe
Speaker 1: the universe in terms of like balls that are being
Speaker 1: against each other, then where are you describing information? Right?
Speaker 1: The concept of information, which we now know to be
Speaker 1: so vital, it's just sort of like an abstract, fuzzy
Speaker 1: thing that comes out of that. It's not like written
Speaker 1: into the core laws of the universe. Right. I think
Speaker 1: what you're saying is that you know because this emergent phenomenon,
Speaker 1: like a great example of it is the weather. And
Speaker 1: I think maybe what you're saying is that our current
Speaker 1: theories allow us to predict, you know, one drop of water,
Speaker 1: what happens to that drop of water, how far it's
Speaker 1: going to fall or where the women's going to take it.
Speaker 1: But to predict like a storm, or to predict, you know,
Speaker 1: how cold it's going to be all over the world,
Speaker 1: that's a much different problem. And your theory is about
Speaker 1: the drop of water. Are not that useful in that
Speaker 1: case in terms of describing the concept of weather. Yeah,
Speaker 1: And anytime you're talking about emergent phenomena, it's always going
Speaker 1: to be approximate because you can't make exact calculations from
Speaker 1: drops of water up to hurricanes, and so it's always
Speaker 1: going to be rough. And so when we talk about information,
Speaker 1: for example, we don't really know in our current theories,
Speaker 1: like what information is, you know, Like I am talking
Speaker 1: right now, which means I'm translating ideas which are in
Speaker 1: my brain into sound waves which gets transformed into electrical
Speaker 1: signals in this microphone and get stored somewhere and then
Speaker 1: eventually transmitted to these listeners. And that information hasn't changed, right,
Speaker 1: But it's lived in lots of different physical systems. It's
Speaker 1: been in shaking air waves, it's been in vibrating electrons,
Speaker 1: it's been in neurons firing. But it's described by all
Speaker 1: these different physical systems, but none of our laws of
Speaker 1: physics really tell us what it is. It seems to
Speaker 1: be sort of like independent from the physics itself, right,
Speaker 1: it's not captured by any of the laws that we're
Speaker 1: using currently. Interesting. Well, I mean that's kind of a
Speaker 1: philosophical question, right, Is information physical a physical phenomenon or
Speaker 1: is it like an abstract kind of like math? Right,
Speaker 1: Like math is not necessarily a physical phenomenon, but it's
Speaker 1: still a phenomenon, right, Well, mathematics absolutely can be abstract,
Speaker 1: but information definitely has to be physical. It's about the
Speaker 1: arrangement of physical objects. Right. You need a universe in
Speaker 1: order to contain any information. So it's definitely a physical thing,
Speaker 1: but it's not clear like where it is and sort
Speaker 1: of like a gap in our current description of the universe.
Speaker 1: And we have approximate ways to describe it, you know,
Speaker 1: like the Shannon law of information captures the amount of
Speaker 1: information you could store in a system, but again it's
Speaker 1: sort of approximate. And that's you know, a motivation for
Speaker 1: how you might design a different set of laws of physics.
Speaker 1: Instead of letting important concepts emerge sort of approximately from
Speaker 1: other laws, write them into the very core of the
Speaker 1: new theories. Well, my head is definitely rolling a little
Speaker 1: bit right now, and so let's get more into this
Speaker 1: idea of information and what this constructors they theory is.
Speaker 1: But first let's take a quick break. Alright. We're talking
Speaker 1: about the potential next revolution in theoretical physics, the idea
Speaker 1: that might change not just science but the way we
Speaker 1: do science. And right now, an interesting candidate for this
Speaker 1: is a theory called constructor theory. And Daniel, you were
Speaker 1: telling me that it's sort of arose because we have
Speaker 1: this gap in our current theories between what we think
Speaker 1: is physical and this idea of information which sort of
Speaker 1: emerges from physical phenomenons, but it's not in our theories
Speaker 1: currently connected to the kind of physical laws we have. Yeah,
Speaker 1: and you know, I think it isn't really interesting and
Speaker 1: deep philosophical question, you know, about whether information is physical.
Speaker 1: And I think to me, the best argument that information
Speaker 1: has to be physical is that the laws that govern
Speaker 1: it are eventually the laws of physics. It's sort of
Speaker 1: like computing shan you know, like the laws of computation.
Speaker 1: What you can and cannot calculate depend on the computer
Speaker 1: that you build and the rules that it follows, which
Speaker 1: in the end must be physical laws, which is different
Speaker 1: from like, you know, the laws about prime numbers, which
Speaker 1: are purely abstract. Doesn't really matter if you have a
Speaker 1: universe as long as you have numbers. But numbers sort
Speaker 1: of represent physical things, right Like two means too of something,
Speaker 1: three means three of something. I guess I'm getting confused here. Yeah,
Speaker 1: they can, but they don't necessarily have to, Like the
Speaker 1: numbers can just be pure numbers in and of themselves.
Speaker 1: But I think the point to underscore is that there
Speaker 1: are these properties of the universe, things like information, that
Speaker 1: we recognize are really important and might even like govern
Speaker 1: how things operate. Right, Like we've talked about how black
Speaker 1: holes are a mystery because they seem to eat information
Speaker 1: and then evaporate and we don't understand it. So it
Speaker 1: affects how things operate in the universe. And yet it's
Speaker 1: not like something we deeply understand. It's just something that
Speaker 1: sort of arises from the other laws that we've written.
Speaker 1: I see. It's like, if you realize information is important
Speaker 1: maybe to the whereas our theories that we've built so
Speaker 1: far are not good for handling that or don't know
Speaker 1: how to define it or incorporated into the physical laws
Speaker 1: exactly if you write the universe as an initial value,
Speaker 1: problem is just like here's the configuration of stuff, and
Speaker 1: here the rules for how that configuration can change. And
Speaker 1: there's no room for like really encoding information deeply into
Speaker 1: the universe. And I think that was probably the impetus
Speaker 1: for this new constructor theory that was actually broader than that.
Speaker 1: It's not just about information. It's about how to write
Speaker 1: new rules of physics that do let you encode things
Speaker 1: like information in them. All right, well, step us through this.
Speaker 1: How is this new theory different or what is it about?
Speaker 1: How does it do things differently? So it's called constructor theory,
Speaker 1: and at first glance it sounds exactly the same as
Speaker 1: the current way we're doing things. Constructor theory is all
Speaker 1: about understanding how the universe transforms from one state to another.
Speaker 1: Like you have a current setup of the universe, you
Speaker 1: have all your particles arranged in one way. It's all
Speaker 1: about understanding what options are available for how those particles
Speaker 1: can transform in the future. And that sounds a lot
Speaker 1: like what we just talked about, which is like, you
Speaker 1: have a bunch of stuff, how does it change as
Speaker 1: you go into the future. There's a crucial difference, which
Speaker 1: is that constructor theory doesn't just want to talk about
Speaker 1: what happens. It wants to talk about what could have
Speaker 1: happened and what could not have happened. It's really focused
Speaker 1: on these a loud transformations and disallowed transformations. Rather than
Speaker 1: just thinking about what happens, it wants to think about
Speaker 1: what the rules are for what could have happened. So
Speaker 1: there are all these like counter factuals they call them,
Speaker 1: these other possibilities for things that could have happened in
Speaker 1: the universe but just didn't happen to occur this time.
Speaker 1: That constructor theory examines that our current theory doesn't I see,
Speaker 1: but doesn't our current theory also sort of do that,
Speaker 1: especially with quantum dynamics, like we have a state of
Speaker 1: the system, and the laws of physics tells where that
Speaker 1: state can go and what it cannot do or what's
Speaker 1: more likely to happen or what it's less likely to happen.
Speaker 1: Isn't that kind of what we have now? Or are
Speaker 1: you saying there's something more sort of allowable not allowable
Speaker 1: about it. It's more of the second. It's about what
Speaker 1: allow out and what's not allowed. You're right, the quantum
Speaker 1: theory is probabilistic in the end. Once you've calculated the
Speaker 1: wave function, you can then predict what might happen, and
Speaker 1: there are various options. But quantum theory is also fundamentally
Speaker 1: deterministic when it comes to calculating the wave function. If
Speaker 1: you have a certain wave function and you put it
Speaker 1: through some system, you know exactly what the wave function
Speaker 1: is going to look like. On the other side, it's
Speaker 1: totally described by the Shorteninger equation. Now when it comes
Speaker 1: to measuring it in the wave function collapse, nobody has
Speaker 1: that figured out yet. But the actual wave function itself
Speaker 1: is deterministic, and our current theories say, well, you have
Speaker 1: one wave function, will tell you how to evolve it
Speaker 1: to the wave function in the future. This constructor theory
Speaker 1: would say, if you have this wave function, what's allowed,
Speaker 1: what's possible for this wave function to happen? And so
Speaker 1: it sort of examines other versions of the universe, you know,
Speaker 1: to consider what else might happen, I say at a
Speaker 1: fundamental level, or like at a specific system, like if
Speaker 1: I have a baseball or I have a canister full
Speaker 1: of gas, molecules, Does it tell me what's allowed for
Speaker 1: those things? Or is this more in a fundamental level,
Speaker 1: like what can a system in general do or not do? Yeah,
Speaker 1: it's at a more fundamental level. And again it's not
Speaker 1: rewriting the laws of physics. It's not saying this canister
Speaker 1: of gas is now allowed to do things that it
Speaker 1: couldn't do before. It's saying, when you go to write
Speaker 1: the laws of physics, instead of just thinking about what's
Speaker 1: going to happen, think about what's allowed and what's not allowed,
Speaker 1: and that will let you write the laws of physics
Speaker 1: in a different way, because, for example, information is not
Speaker 1: just about the current state of your set of switches.
Speaker 1: For example, it's about how many different states could those
Speaker 1: switches hold. Right. If you have like a bank of
Speaker 1: buttons in front of you, the amount of information stored
Speaker 1: in it depends on the number of possible different ways
Speaker 1: those buttons could be pressed or not. So thinking about
Speaker 1: what's allowed and what's not allowed lets you like encode
Speaker 1: information sort of more towards the core of your physical theory.
Speaker 1: M I see. I think maybe what might be confusing
Speaker 1: is that maybe you know physicists and theoretical people sort
Speaker 1: of have a different idea of what information is. Kind
Speaker 1: of like information maybe for to a regular person is
Speaker 1: just like is the light on or off? Or is
Speaker 1: as object red or not read? You know, like that's information.
Speaker 1: That's good, that's sometimes useful to know. But I think
Speaker 1: that maybe a theoretical person, information is more abstract, right,
Speaker 1: It's about what can you know about something? Yeah, And
Speaker 1: it's about like how many different configurations can something hold?
Speaker 1: Like your hard drive, for example, it can store a
Speaker 1: bunch of pictures. Why can it store that many pictures
Speaker 1: because inside of it there are thousands and billions and
Speaker 1: trillions maybe of tiny little switches which can either be
Speaker 1: on or off, and you can encode those pictures in
Speaker 1: those patterns of on and off switches. And so a
Speaker 1: hard drive with more switches can hold more information because
Speaker 1: it can have lots more different patterns, and so it
Speaker 1: can hold bigger pictures or more pictures. So we measure
Speaker 1: the information in a system by how many different states
Speaker 1: can it be in, because that's a way to code
Speaker 1: some vital thing. Like if you have, for example, just
Speaker 1: a light switch, a light switch can only be in
Speaker 1: two states, on or off, so you can only possibly
Speaker 1: send two messages. Right, you can't send a picture of
Speaker 1: your dog using a light switch or a picture of
Speaker 1: your cat. But if you have a billion light switches,
Speaker 1: then you can flip them in the way which means
Speaker 1: the picture of your dog or means the picture of
Speaker 1: your cat. Right. I feel like it's almost like, you know,
Speaker 1: information for for a regular person is like whether a
Speaker 1: ball is red, Like that's information. But to the radical person,
Speaker 1: it's like how many colors can this ball be? More
Speaker 1: colors it can be. The more information that ball has
Speaker 1: or carries, or you know, manifests perfectly. I think that's
Speaker 1: a great way to describe it. Good. I'm glad, I
Speaker 1: wasn't happy. So if we then think about our laws
Speaker 1: of physics in terms of like could this ball have
Speaker 1: been red? Or could have been blue? Or could it
Speaker 1: have been green, then we're thinking about the possible states
Speaker 1: of the system. We're thinking about what could have happened
Speaker 1: and what couldn't have happened. Then we're directly addressing the
Speaker 1: information when we go to write those laws of physics. Right,
Speaker 1: So it sounds like you're concerned about all of the
Speaker 1: different arrangements of a system, and so our current theories
Speaker 1: don't worry because they only sort of deal with one
Speaker 1: arrangement at a time kind of. And so constructor theory says,
Speaker 1: the first thing you do is not write down the
Speaker 1: laws of what happens. The first thing you do is
Speaker 1: you write down what can happen and what can't happen,
Speaker 1: and you use that to constrain eventually the laws that
Speaker 1: you do write about what does happen. So it says,
Speaker 1: start instead from basic principles about what's allowed and what's
Speaker 1: not allowed, and then go from there. Instead of starting
Speaker 1: from how things move and then figuring out what the
Speaker 1: laws of what's allowed and what's not allowed are and
Speaker 1: making them in exact, start from exact laws of what's
Speaker 1: allowed and what's not allowed, and from their right the
Speaker 1: rest of the dynamics, and by allowed or not allowed
Speaker 1: to me like from an information point of view, like
Speaker 1: information can increase or decrease or things like that. That's
Speaker 1: one example, but it's really quite general, and you know
Speaker 1: there are examples in the past where this has worked
Speaker 1: really really well. We know, for example, that special relativity
Speaker 1: is a great example. We know that Einstein got the
Speaker 1: idea for special relativity from observing that the speed of
Speaker 1: light is constant. Once you start from that, you write
Speaker 1: down this basic principle, then the rest of special relativity
Speaker 1: sort of falls just from that. So if you start
Speaker 1: by saying, here the basic rules of what's allowed, everybody
Speaker 1: who measures the speed of light has to measure it
Speaker 1: at the same speed, no matter what their velocity is. Right,
Speaker 1: from that, that constrains the possible laws of physics that
Speaker 1: you could develop, and it constrains it in a way
Speaker 1: that gives us special relativity the only rules that are
Speaker 1: consistent with that. So it's a great example of starting
Speaker 1: from principles and then finding laws of physics rather than
Speaker 1: starting from the other direction. Yeah, because I guess if
Speaker 1: you had started from like just looking at a photon,
Speaker 1: you might have built a different theory about the universe, right,
Speaker 1: and one in which like could go as fast as
Speaker 1: it once, or anything can go as fast as it once.
Speaker 1: But you're saying, like relativity something that came from looking
Speaker 1: at what's allowed and not allowed. First, Like, we've observed
Speaker 1: that nothing can go fast in than the speed of light,
Speaker 1: and therefore photons have to move this way with these laws. Yeah,
Speaker 1: and before we had relativity, we knew that light travel
Speaker 1: just at that speed. It was measured, but it wasn't
Speaker 1: an exact statement, you know, something that sort of emerged
Speaker 1: approximately from experiments and from our calculations and from electromagnetism.
Speaker 1: You know that light moved at this speed, but it
Speaker 1: wasn't an exact principle. It was approximate. So Einstein instead
Speaker 1: enshrined it as an exact statement, right, and he said
Speaker 1: this has to be true absolutely, and everything follows from that.
Speaker 1: And he did something similar when he developed general relativity. Right.
Speaker 1: In general relativity, he said that acceleration is indistinguishable from gravitation,
Speaker 1: that you can't tell the difference between accelerating and being
Speaker 1: an a gravitational field, and that principle led him to
Speaker 1: general relativity. So it's been done before in the past
Speaker 1: in this general sense of like, find the basic principles
Speaker 1: and from that let the laws of physics flow, instead
Speaker 1: of let's build up mechanics and then see what emerges
Speaker 1: from it. Well, it almost feels like you're trying to
Speaker 1: state what the laws are and then I hope they
Speaker 1: were or see if they work, rather than you know,
Speaker 1: the kind of discover what those laws are. Yeah, maybe
Speaker 1: it is a little bit backwards. You know, it's sort
Speaker 1: of like, assume some basic principles about what's allowed in
Speaker 1: the universe and what's not allowed. See what the consequences
Speaker 1: of that are. But then in the end you still
Speaker 1: have to go out and check and say, well, does
Speaker 1: that actually describe reality or not? If Einstein's predictions hadn't worked,
Speaker 1: then you would have to toss it out, no matter
Speaker 1: how beautiful it was. It seems like a bit of
Speaker 1: a scatter approach. You know, I could say, hey, maybe
Speaker 1: only pink elephants can go faster than the speed of light,
Speaker 1: and so I would we would have to design an
Speaker 1: experiment to prove me wrong. I'm looking forward to doing
Speaker 1: that experiment. Actually a great way to spend an Afternoon's right,
Speaker 1: It's been a few months writing that application. But what
Speaker 1: are some other examples of this idea kind of working out?
Speaker 1: Another example is Stephen Hawking making progress on quantum gravity.
Speaker 1: You know, we have a theory of quantum mechanics that
Speaker 1: describes how particles move, and then we have general relativity
Speaker 1: that tells us how space bends and twists in the
Speaker 1: presence of mass. But nobody's been able to link those
Speaker 1: two together to understand how gravity affects tiny little particles
Speaker 1: which seem to follow very different rules then the things
Speaker 1: that general relativity talks about. Right, general relativity is happy
Speaker 1: to talk about baseballs and planets and things that follow smooth, continuous,
Speaker 1: curved paths, but quantum mechanics tells us particles don't do that.
Speaker 1: They're here, then they're there, and there is no path
Speaker 1: in between them, and sometimes they can be in multiple
Speaker 1: places simultaneously, right, or have the probability to be, and
Speaker 1: general relativity doesn't know how to handle that. And so
Speaker 1: Stephen Hawkings said, well, let me think about what's allowed
Speaker 1: for black holes and what's not allowed. And he said, well,
Speaker 1: we know that black holes have some information inside of them,
Speaker 1: because when you put something inside a black hole, that
Speaker 1: information has to go somewhere. And therefore black holes have entropy,
Speaker 1: they have disorder because they're gathering information to gathering stuff
Speaker 1: as they grow, and therefore they have to have some temperature.
Speaker 1: And this was his big breakthrough, is to apply like
Speaker 1: statistical thermal physics to black holes, because if black holes
Speaker 1: have some temperature, then they have to glow because everything
Speaker 1: in the universe that has a temperature also emits radiation,
Speaker 1: and that led him to predict talking radiation, which he
Speaker 1: of course named after himself. And so that was sort
Speaker 1: of like a first step in the direction of trying
Speaker 1: to understand a quantum theory of gravity, like what happens
Speaker 1: to tiny particles right on the boundary of a black hole.
Speaker 1: Of course, not a full theory of quantum gravity, lots
Speaker 1: of big questions remaining, but it's sort of like a
Speaker 1: good step forwards starting from making statements about what is
Speaker 1: allowed for black holes. It sort of sounds like maybe
Speaker 1: the the idea it has to do with abstraction, maybe
Speaker 1: like you're abstracting something from you know, a bird's eye
Speaker 1: view really high up, and you say, all right, what,
Speaker 1: what's sort of the general shape of this or what
Speaker 1: should this behave as a whole, like a black hole?
Speaker 1: Like if I just treat a black hole as a
Speaker 1: black body, or is it hot thing in space, then
Speaker 1: these are the things that should expect from it. And
Speaker 1: then after that you sort of go into the Nitta
Speaker 1: greety to make sure that's true. And then that maybe
Speaker 1: reveals the small details of the laws of physics exactly
Speaker 1: and it constrains you, right, it forces you to only
Speaker 1: consider certain kinds of laws of physics, and the thing
Speaker 1: that I like about it is that it does really
Speaker 1: enshrine important things fun mentally into the theory and makes
Speaker 1: them exact rather than approximate. I think about conservation of energy.
Speaker 1: You know, if you didn't know that energy was conserved,
Speaker 1: if that wasn't like a core thing in your theory,
Speaker 1: and you just made a bunch of measurements and developed
Speaker 1: the theory of chemistry and physics, then you might end
Speaker 1: up with like an approximate conservation of energy because you
Speaker 1: might notice like energy is almost always pretty close to
Speaker 1: exactly conserved, but you wouldn't discover that it's like actually
Speaker 1: really conserved. That takes like a reformulation of your theory
Speaker 1: to say, well, you know what, we're going to put
Speaker 1: this in at the ground level because it seems like
Speaker 1: it really is exact. I see, you mean, like the
Speaker 1: laws of thermodynamics, it's like, you know, we sort of
Speaker 1: observed that they were true that you know, entropy always
Speaker 1: increases or energy is sort of always conserved. But let's
Speaker 1: just assume that's always true in all cases and then
Speaker 1: build the theory of how molecules and things in a
Speaker 1: gas canister work after that. Yeah, and let's see where
Speaker 1: that leads us. Right, let's put these handcuffs on ourselves,
Speaker 1: assuming that the universe also obeys those restrictions, and see
Speaker 1: where that leads us. And it will lead you to
Speaker 1: a theory which, if that describes the universe, should be
Speaker 1: closer to the true theory. Or it might lead you
Speaker 1: to a pink elephant collider or launching some pink elephants
Speaker 1: into space exactly, and you might be handcuffed to that
Speaker 1: pink elephant, and so it might be quite a ride.
Speaker 1: We'll put those physicists in the back room. We'll attach
Speaker 1: them to the pink elephants. All right, Then, what are
Speaker 1: some maybe new developments in this theory about constructing from
Speaker 1: the ground up. Well, one big obstacle in developing like
Speaker 1: a theory of quantum gravity, which in the end is
Speaker 1: one of the real big motivations for this. Like we
Speaker 1: haven't figured out quantum gravity. What's going on. We've been
Speaker 1: working on this for a while. Maybe we need a
Speaker 1: new approach. One obstacle to making progress there has been
Speaker 1: that we don't really know which direction to take. Like
Speaker 1: there's two possibilities. One is maybe gravity is a force
Speaker 1: like everything else, you know, like electromagnetism and the weak
Speaker 1: force and the strong force. Gravity really is a force,
Speaker 1: and it's quantum mechanical, and they're like little gravitons that
Speaker 1: go back and forth. Maybe we can use our whole
Speaker 1: quantum mechanical description of the other force is and we
Speaker 1: can apply it to gravity somehow. We haven't figured out
Speaker 1: how yet, but maybe that's the path forward. But then
Speaker 1: there's a whole other group of people who are taking
Speaker 1: a completely different approach. They're saying, no, no, no no, gravity
Speaker 1: is different. And the way to bring general relativity and
Speaker 1: space and time together with quantum mechanics is not to
Speaker 1: quantize gravity, but to quantize space itself. This idea that
Speaker 1: like maybe space is made out of tiny little pixels
Speaker 1: and reality is like woving together this loop or this
Speaker 1: foam of these tiny little pixels. That would also make
Speaker 1: gravity quantized, but in a very very different way. It
Speaker 1: wouldn't say gravity is a force. They would say it's
Speaker 1: the curvature of space, but that space itself is quantized,
Speaker 1: so nobody really knows like which direction to take. And
Speaker 1: there's this idea that if we could construct an experiment
Speaker 1: to sort of like, not tell us how gravity works,
Speaker 1: but tell us which direction to go. That that could
Speaker 1: be a very useful thing to do to like at
Speaker 1: least get a clue as to which path to take.
Speaker 1: And I see it's like we can marry the two
Speaker 1: theories together. So let's just invent a marriage and see
Speaker 1: if we can get the right theory from there. Yeah,
Speaker 1: and so people are wondering, like, is gravity a quantum
Speaker 1: force or is space itself quantized? And before we know
Speaker 1: which direction to take, let's say if maybe we can
Speaker 1: answer that question, And so constructor theory would say, that's
Speaker 1: very important step to take first is to understand is
Speaker 1: gravity quantum theory or is space itself quantized? You should
Speaker 1: try to figure that out first, and then you should
Speaker 1: proceed to try to figure out quantum gravity. And you
Speaker 1: might think, well, yeah, it would be great to know that,
Speaker 1: but how could you possibly figure that out? And people
Speaker 1: actually have come up with a pretty cool idea for
Speaker 1: how you might be able to figure out if gravity
Speaker 1: is a quantum force without actually understanding quantum gravity itself.
Speaker 1: All right, right, let's get into some of the details
Speaker 1: of this arranged marriage and how it might let you
Speaker 1: copy information in new and interesting ways. But first, let's
Speaker 1: take another quick break. All right, we're talking about constructor theory,
Speaker 1: which is not a childhood toy. It's like potentially revolution
Speaker 1: in the way physicists think about the universe and how
Speaker 1: they build theories that describe the universe. And so we
Speaker 1: think it's a better approach because it might let us
Speaker 1: connect physics two concepts that are currently not connected together,
Speaker 1: like maybe information to physical laws, or marrying quantum mechanics
Speaker 1: to gravity. And so, Daniel, we were talking about marrying
Speaker 1: quantum mechanics to gravity, which we currently don't have. They
Speaker 1: won't even talk to each other right now, So how
Speaker 1: do we make this romance happen? Well, first we have
Speaker 1: to figure out, you know, how this relationship is going
Speaker 1: to work. Right, Are we gonna stick gravity into quantum mechanics?
Speaker 1: Are we're gonna stick quantum mechanics into gravity. It's like
Speaker 1: are we wrapping the peanut butter around the chocolate or
Speaker 1: the chocolate around the peanut butter. That's like step number one.
Speaker 1: That's what constructors theory would say. It's like instead of
Speaker 1: like fiddling around in the lab trying to build a
Speaker 1: theory from scratch and from watching individual particles. Let's decide
Speaker 1: from the beginning whether it's chocolate and peanut butter or
Speaker 1: peanut butter and chocolate. Yeah, let's have as many guiding
Speaker 1: principles as possible before we get started, and let's code
Speaker 1: those guiding principles into the very very basic layer of
Speaker 1: how we design this theory, so it's more likely to
Speaker 1: be right in the end. And you know that only
Speaker 1: works if the principles you're talking about are the ones
Speaker 1: that describe our universe, so you better make sure those
Speaker 1: are right. Well, it tell us a little anti scientific
Speaker 1: in a way, right, Like it's almost like you're pre
Speaker 1: coming up with the answer in a way instead of
Speaker 1: basing it on observation. It's like another step in developing hypotheses. Right,
Speaker 1: It's like step zeros. Now, write down a bunch of
Speaker 1: rules that your theories have to obey, and then step
Speaker 1: one is write down a theory of the universe, and
Speaker 1: then step two is go out and check and see
Speaker 1: if it actually works. But we have this like new
Speaker 1: step zero the constrains the kind of theories you can
Speaker 1: write down, and step one I see, So it's like
Speaker 1: a meta hypothesis. It's before we have a hypothesis. Let's
Speaker 1: step back and have a meta hypothesis where we sort
Speaker 1: of pick a direction of the way the universe is
Speaker 1: peanut butter or chocolate coated, and then see if that works.
Speaker 1: If it doesn't, then we'll maybe try another direction. And
Speaker 1: the advantage is if it does work, then these like
Speaker 1: D principles are encoded right into your laws of physics.
Speaker 1: They're exact rather than like coming out as emergent or
Speaker 1: approximate phenomena. But wouldn't the danger be that maybe you
Speaker 1: pick a direction like chocolate covered inside a peanut butter,
Speaker 1: and it works most of the time, but then eventually
Speaker 1: down the road it turns out that it's, you know,
Speaker 1: also an emergent thing or something. Yeah, you could take
Speaker 1: a principle and claim that it's perfect and exactly, then
Speaker 1: it could turn out to just be approximate. Absolutely, there's
Speaker 1: nothing in this new constructor theory that prevents you from
Speaker 1: overthrowing people's previous ideas developed from constructor theory. Right, you
Speaker 1: can still do that, all right, But what I do
Speaker 1: think is really fun is that it's motivated people to
Speaker 1: try to ask this question of like the chocolate in
Speaker 1: the peanut butter peanut butter and the chocolate before we
Speaker 1: get to quantum gravity. It's like, first figure out which
Speaker 1: direction to take before you actually get the theory. I
Speaker 1: think that is pretty cool. That is something new because
Speaker 1: it actually inspired people to think up a really clever
Speaker 1: experiment that would answer that question. How does quantum gravity work?
Speaker 1: But is gravity quantum force or is space quantized? Oh?
Speaker 1: I see, Like maybe before because we didn't know whether
Speaker 1: it was peanut butter or chocolate, the one that was outside.
Speaker 1: You know, people wouldn't commit to sort of exploring experiments
Speaker 1: or going down one path too much. But once you
Speaker 1: sort of say, okay, let's assume it is chocolate covered
Speaker 1: with peanut butter, and how would we build a whole
Speaker 1: science out of this? Yeah, it's really inspirational to know
Speaker 1: something about the answer. It really helps you drive in
Speaker 1: the right direction. But these experiments are really hard, right
Speaker 1: because what we're looking to do is to understand do
Speaker 1: tiny little particles feel gravity or how do they feel gravity?
Speaker 1: What are the rules of gravity for tiny particles? And
Speaker 1: that's hard because tiny particles are tiny and gravity is
Speaker 1: really really weak, and so like the gravitational forces between
Speaker 1: two tiny particles are almost zero, which makes it really
Speaker 1: hard to do experiments of like measuring the gravitational forces
Speaker 1: between two electrons, for example. MM. So you're saying that
Speaker 1: maybe just the idea of starting with like is a
Speaker 1: would be a quantum force has inspired a whole bunch
Speaker 1: of interesting experiments or interesting ideas about how that could work.
Speaker 1: Whereas before people didn't really want to go down that
Speaker 1: rabbit hole. People thought for a while that that was
Speaker 1: not a question we could answer. First. People thought, first,
Speaker 1: let's find a working theory of quantum gravity. Then we
Speaker 1: can ask questions of that theory and say, like, well,
Speaker 1: does it tell us that gravity is a quantum force
Speaker 1: or does it tell us that the universe is quantized? Now,
Speaker 1: instead they're saying, well, let's figure that out first, and oh, actually,
Speaker 1: it might be possible to figure that out experimentally in
Speaker 1: the next few years, and then we can use that
Speaker 1: at the core of our theory and we can build
Speaker 1: from there. So what does this experiment look like. It's
Speaker 1: really fun. It's a crazy bonkers experiment. It involves these
Speaker 1: super tiny little micro diamonds that are really small, and
Speaker 1: inside of them they have like a single nitrogen atom
Speaker 1: that can have different quantum states like different spin spin
Speaker 1: up or spin down. The idea is that these diamonds
Speaker 1: are so small that they're basically quantum mechanical, and the
Speaker 1: goal of the experiment is to put these diamonds in
Speaker 1: a quantum superposition. So like you have two diamonds and
Speaker 1: you know, call one red and one blue, and maybe
Speaker 1: the red one is now in a quantum superposition where
Speaker 1: it like it could be over here or it could
Speaker 1: be over there, and the blue one is also in
Speaker 1: a position of where it might be. Now that's interesting
Speaker 1: because gravity, of course depends on the distance between things.
Speaker 1: So the part of the red diamond that might be
Speaker 1: closer to the blue one should have a stronger gravitational
Speaker 1: force than the part of the red diamond that might
Speaker 1: be further away from it. So now you have this
Speaker 1: like red diamonds in these quantum superpositions, and different parts
Speaker 1: of those wave functions are now affected differently by the gravity.
Speaker 1: And so if gravity is a quantum force, it will
Speaker 1: talk to the different parts of those wave functions differently
Speaker 1: than if gravity is not a quantum force, and it
Speaker 1: like collapses that way function before interacting with it. So
Speaker 1: you put these diamonds in like quantum superpositions, and then
Speaker 1: you can see if gravity plays nicely with quantum states
Speaker 1: or not. You mean, like almost like you're taking two
Speaker 1: atoms and putting them close to each other and see
Speaker 1: if there's a gravity between them. Kind of, Yes, these
Speaker 1: diamonds drift through the experiment, they fall through the experiment,
Speaker 1: and then they measured the distance between them to see
Speaker 1: how gravity has tugged on these two diamonds between each other.
Speaker 1: But before they did that, they put this quantum uncertainty
Speaker 1: into the location of the diamonds, so it's not exactly
Speaker 1: clear where the diamonds are. So then gravity has to
Speaker 1: make a choice. It's like, well, my classical do I
Speaker 1: collapse the wave function and then make gravity happen? Or
Speaker 1: am I cool with quantum stuff because I'm a quantum
Speaker 1: force just like everybody else, and I can just like
Speaker 1: gravitationally attract the various bits of the wave function to
Speaker 1: each other. Interesting, I guess you're saying that if gravity
Speaker 1: changes the quantum wave function of the individual particles, that
Speaker 1: means that it's a quantum force, whereas if it only
Speaker 1: acts after you collapse the wave function, then it's not
Speaker 1: a quantum force. Exactly, and this experiment can tell the
Speaker 1: difference because it has these tiny little diamonds in quantum superpositions,
Speaker 1: and it can tell the difference between gravity collapsing those
Speaker 1: wave functions and then acting or gravity acting separately on
Speaker 1: the parts of the wave function, which would mean it's
Speaker 1: a quantum force. M M. I see, because it sounds
Speaker 1: like a really cool experiment and that maybe we should
Speaker 1: have thought of a while ago. That you're saying that
Speaker 1: we only sort of thought about it or only conceived
Speaker 1: this experiment because of this constructor approach of like let's
Speaker 1: pick a direction and go with it and then think
Speaker 1: of experiments or theories that fit that general meta hypothesis. Yeah,
Speaker 1: it was Kira Marletto herself who came up with this
Speaker 1: experiment as a sort of demonstration. She was thinking, if
Speaker 1: you want to figure out the basic principles first, you
Speaker 1: could actually try to attack those directly. And this is
Speaker 1: a good example of why like motivational principles or organizational
Speaker 1: strategies for theoretical physics are really important, because you're right
Speaker 1: that somebody could have thought of this ten years ago
Speaker 1: or twenty years ago, right, But the motivation for thinking
Speaker 1: up that this experiment was possible. Came from a new
Speaker 1: way of asking questions about the universe of let's try
Speaker 1: to figure out some basic principles first that will guide
Speaker 1: our theory going forward. I see, like, how would you
Speaker 1: design something directly to test those meta hypotheses. It's not
Speaker 1: something we would have come up with before, because before
Speaker 1: we were sort of tinkling around with the atoms and
Speaker 1: the particles and trying to see what was going on.
Speaker 1: And you know, it seems like nobody could sort of
Speaker 1: make heads or tales out of it. Yeah, exactly. So
Speaker 1: now people are setting up to do this experiment, and
Speaker 1: so we may know in the next few years is
Speaker 1: gravity a quantum force or not, which would be a
Speaker 1: huge piece of information. And you know, if it is,
Speaker 1: that means like folks like Carlo Rovelli, w've been working
Speaker 1: in loop quantum gravity. Well, that was fun mathematically, but
Speaker 1: doesn't describe nature. And we can just sort of like
Speaker 1: cross out huge branches of theoretical physics is inconsistent with
Speaker 1: our universe, and then we can dedicate our energies to
Speaker 1: the other direction. I see all those people holding peanut
Speaker 1: butter covered chocolates with the left with a lot of
Speaker 1: calories Uneaten. That's right and also delicious, right, mathematically a
Speaker 1: lot of fun and we've learned a lot about math
Speaker 1: and and maybe even about physics or the metaverse from that,
Speaker 1: but not necessarily our universe. Right, it could be true
Speaker 1: in another universe exactly. Maybe all those physicists will then
Speaker 1: DeCamp and go off to another universe. Follows they'll get
Speaker 1: exiled to in different country. As most revolutions, you know,
Speaker 1: there are always refugees, right, intellectual refugees, good Argentina. Maybe
Speaker 1: we wish them safe voyage. All right, Well, what are
Speaker 1: some of the criticisms of this constructor theory approach. One
Speaker 1: criticism is that, like, haven't we been doing this already?
Speaker 1: You know? The fact that we have previous examples like
Speaker 1: Einstein using this to establish relativity and Hawking using similar
Speaker 1: ideas to establish his ideas about black hole tells us that, like,
Speaker 1: it kind of has been done in the past, so really,
Speaker 1: what's new. I read a bunch of articles criticizing it,
Speaker 1: and that was essentially the strongest argument. I read that, like,
Speaker 1: we've already basically done this, And the response from constructor
Speaker 1: theory folks is like, yeah, we've done it. Before, but
Speaker 1: this like formalizes it, it generalizes it, It identifies it
Speaker 1: as a good way to do things. It encourages us
Speaker 1: to do all of physics this way rather than just
Speaker 1: you know, remarking on a couple of times that we
Speaker 1: did it and it worked. I see, like right now,
Speaker 1: it's sort of random the way we do it. Sometimes
Speaker 1: sometimes we start from the observation, sometimes we start with
Speaker 1: some guiding theory. But it's sort of random, and sometimes
Speaker 1: it works, sometimes it doesn't. I think you're saying this
Speaker 1: sort of camp or a physicist saying, let's just call
Speaker 1: it what it is, and let's know when we're doing
Speaker 1: it and not doing it. Yeah. Another criticism is that
Speaker 1: it's kind of fuzzy. I mean, it's even been tough
Speaker 1: for us to like figure out exactly what it means
Speaker 1: and how it would be different. And I think a
Speaker 1: lot of physicists sort of look at and be like, huh,
Speaker 1: what are you talking about. We're just going to keep
Speaker 1: doing physics the way we're doing physics, And so it
Speaker 1: hasn't like swept the world by storm. I mean, I'm
Speaker 1: here in a hallway with a bunch of theoretical physicists
Speaker 1: and none of them would say that they're doing constructor
Speaker 1: theory or think about constructor theory at all. So it
Speaker 1: might just be that, you know, it takes another few
Speaker 1: years to really catch on, to really break through that
Speaker 1: it needs to have. It's like really killer app before
Speaker 1: people are convinced, or could just be like, hey, that
Speaker 1: was kind of a cute idea, and then people move
Speaker 1: on to something else. We just really don't know at
Speaker 1: this point, right right then people move on to deconstructor theory,
Speaker 1: transformer theory into set to con theory, yeah, therey, and
Speaker 1: finally the knap theory. All right, well, it sounds like
Speaker 1: another state too, and it sounds like a pretty exciting idea,
Speaker 1: maybe a new way to look at science itself, and
Speaker 1: then the way we build theories about the universe, which
Speaker 1: could be maybe the right way. It sounds like a
Speaker 1: lot of progress has been made already thinking in this way,
Speaker 1: and it's always exciting to dig at the foundations of
Speaker 1: science to wonder, are the way we're doing things the
Speaker 1: only way? Is it the best way? We're all gone
Speaker 1: down one path without even realizing there was another path
Speaker 1: back then, a thousand years ago that we could have taken.
Speaker 1: So it's fun to sort of like lift up the
Speaker 1: layers of the rugs and look at what's underneath. And
Speaker 1: sometimes you find something really clever in a new direction. Right,
Speaker 1: Sometimes it's caramel nugat all the way down and not
Speaker 1: peanut butter or chocolate. Sometimes it's turtles all the way down. Right,
Speaker 1: isn't that a candy chocolate turtle chocolate turtle thing? All right? Well,
Speaker 1: another example of how science is an involving thing. It's
Speaker 1: always changing and transforming and constructing itself. And then and
Speaker 1: maybe the people out there who are listening could be
Speaker 1: the ones who may could all work. That's right. Maybe
Speaker 1: some six year old or some eight year old or
Speaker 1: some thirty eight year old out there is the one
Speaker 1: with the new idea about how the universe works, the
Speaker 1: one that takes us to the next level of understanding reality.
Speaker 1: So hopefully they'll wake up from their nap and figure
Speaker 1: everything out. For you, guys, we hope you enjoyed that.
Speaker 1: Thanks for joining us, See you next time. Thanks for listening,
Speaker 1: and remember that Daniel and Jorge explained the universe is
Speaker 1: a production of I Heart Radio or more podcast from
Speaker 1: my heart Radio. Visit the i heart Radio app Apple
Speaker 1: podcasts or wherever you listen to your favorite shows. YE