Why does physics even work?

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Speaker 1: Science seems to work. We can argue about the philosophical foundations of it, and whether a photon is a particle or a wave. We can wonder whether the universe that we perceive out there is real or is just an elaborate hoax like in the matrix, and how we might ever know the difference. But in the end, what is beyond question is that science does work. We can build airplanes that almost never crash. We can build incredible miniature devices that rely on the quantum properties of electrons. We can and have sent robots to crawl over the surface of other planets and send us back pictures. All of this stuff works because of science. Science lets us build and test and refine little mathematical stories about how things work, and then calm definitely use those mathematical principles in totally different contexts. Ideas that we have in the shower, then test in basement labs. They all work inside your iPhone and on the space station. We can confidently use what we have learned, even if we aren't exactly sure why science works and whether the universe out there is actually real. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I want to know what's real about the universe. I don't want to just have ideas that work. I want to know the truth about the universe. And welcome the podcast Daniel and Jorge Explain the Universe, where our goal is to do just that, to explore with you what we do and don't know about the universe, how microscopic little particles interact at the smallest levels, and how all of their twoing and frowing and buzzing weaves itself together into the world that we know with very different rules, which is just a small part of the larger context of stars and galaxies and superclusters slashing around in a web of dark matter to make this glorious and crazy universe. My co host and a friend, Jorge, is on vacation this week, so I'm taking the opportunity to take a bit of a digression into the philosophy of science, together with an exciting guest. Now, what's amazing to me about science is that we are capable at all of understanding the universe that jumped up apes with tiny little brains on a little rock in an irrelevant galaxy can just by doing a few experiments and writing down some math symbols build a mental model of how the universe works, and a model that seems to work pretty well. This model has revealed how stars form, and how the universe expands, and how electrons funnel through weird metals, and how the whole universe is filled with an invisible Higgs field that gives matter to microscopic particles. It's incredible what we have learned about the nature of the universe. The very fact that you are hearing this podcast right now relies deeply on our understanding of the basic rules of the universe and our ability to manipulate and rely on them. But why is that possible? Why does it even work? Because what I said a moment ago was a bit of a stretch of the truth. For all of the successes of particle physics, we don't actually have an understanding of the basic rules of the universe. We don't know what the basic bits of the universe are and what their rules are. Are they strings? Is it a quantum foam? Is it something completely different than we haven't yet or maybe could never even imagine or grapple with. What we do have is a set of rules that work for the experiments that we can do, but we're pretty sure it's not the final answer, not that they're wrong and it's all a hoax, but that it will be eventually replaced by a deeper understanding. The way Newton's physics worked for the experiments that could be done in his day, but we're later replaced by Einstein's more general theory. The way you can use F equals m A to calculate how a ball flies through the air, and it certainly works even if you don't understand the quantum frothing happening inside of it. What we have in particle physics is the same thing. We don't think it's fundamental. We don't think it describes the basic bits of the universe. We think it's effective, meaning that it works, but it describes things that emerge from the fundamental pieces. But it still works even though we don't know what the basic pieces are and the rules that they obey. We have found the non basic pieces and the rules that those non basic pieces obey. For example, we have rules of economics and they mostly work. But people and money are not fundamental elements of the universe. You can have a universe without people and money, and most of the history of the universe didn't have people or money. But once people and money emerge, you don't have to describe the economy of a country using particle physics or string theory. You can find basic mathematical laws that describe economics and are pretty simple, just like F equals I may is pretty simple, but it ignores all of the quantum details underneath. So why does that work? Why is it possible? And what does it mean about whether what we have learned is true and fundamental to the universe, a real description of what's out there, or if it's just a set of mathematical stories that humans tell ourselves that happen to work very well. So today on the podcast, we'll be asking the question why does physics even work? Why is it possible to tell mathematical stories about the universe out there without knowing the deepest underlying truth. We know it's possible to make chicken soup and iPhones without knowing quantum gravity, but why can we Does that mean that the stories we are telling, the physics ideas we have developed are not real in some deep, true sense. Would alien scientists come up with the same theories or have a different concept of how to describe the universe. To help us probe these questions, I've invited an expert in this area, Professor Tim O'Connor. Tim is a professor of philosophy and cognitive science at Indiana University, where he specializes in these types of questions and especially the phenomenon of emergence cases where it's possible to describe things at a higher level without knowing the underlying pieces. So it's my pleasure to introduce to the podcast Professor Tim O'Connor Tim. Thank you very much for joining us today. Glad to be with you, Daniel. As well as being an expert on philosophy of science and emergence, I see that you also claimed the title of Philo Pong World Grand Champion or the world's leading table tennis player among properly credential philosophers. Tell us about how you figure that out? How you determined that you could claim that title. Oh, I declared the title, and the interesting thing is that no philosophers have disputed that I hold the title, and I think the reason is that those who like to play serious table tennis figured out that. Great. Then all I have to do is beat you, and then I get to claim the title. So I have defended the title on a few occasions. Um, but I expect to be losing the title the next time I go back to China. Well, I think it made me says something about philosophy that you can just do, say yourself champion, and then you know, see, if it stands up to scrutiny, that's it. It's kind of like a homesteading thing. If no one disputes it, then at a certain point that's I own it exactly. So, when you're not winning ping pong matches, you're a philosopher of science, tell us about that. What got you into philosophy of science? What are the most important questions in your mind that we should be asking about our universe? Great? Uh so, well, I start out and still think of myself fundamentally as a metaphysician, where metaphysics asks the really most general foundational questions about reality, about fundamental categories like object, property, space, time. Does the physics wholly determine what one should think about space and time? It certainly constraints, um, what one should say, and I'm more in the latter campic constraints, but doesn't wholly determine how we think about it. But the relationship of philosophy metaphysics to science is a challenging question in its own right. And of course the two subjects originally refused in the history of Western thought, going all the way back to thinkers like Aristotle. But well on up to the time of Newton. Um you had a one job title natural philosopher, which was a description of science as we think of it, as those philosophical questions that concerned the natural world. And I think it's beginning with Newton, who famously, when pressed for an account or an explanation of how his theory of gravitational attraction action at a distance, how we could conceive it seemed inconceivable, how we could make sense of that, he famously said about you know, about that, I feigned no hypotheses. And he's beginning to show a certain sort of well, you know, you might ask a certain kind of philosophical question, but as far as doing science, which is what fundamentally Newton was up to, Uh, the theory works beautifully, the mathematics works, it's predictively successful, and so he was willing to go with that. So I want to talk to you specifically in a bit about emergence and how the world that surrounds us arises and how we make sense of it. At first, I want to start with a bigger picture of why we ask these questions. As you say, we see that science works, We know that it does. It's the reason that we're talking right now. So if Newton doesn't care about questions like why does it work? Or you know, is the universe out there real or is it just a story in our minds, why do we care about those questions? Why are those questions important to figure out? Because ultimately, I think we were driven to wanting to have a consumption of reality on which it's explicable. Uh it makes sense. I mean explicable, not in the sense necessarily if involving purpose or anything like that, but just rationally explicable. And so simply retreating to um an instrumentalist few syite of science, UM saying it's science just delivers sophisticated instruments that enable you to predict future observations and ultimate control future patterns to degree through technology. That sort of conception leaves open you know why, but why does it work? It can seem like a cosmic coincidence um, that reality exhibits deep patterns. If all you're willing to say is there are these deep patterns and there's no rational intelligibility behind them. So not everyone shares it, but it's the fundamental philosophical impetus I guess to want to understand why things are as they are. Um, And so depending on one's conception of science, science may or may not even give you that right. So so there are famous scientists too who insisted that in a sense, science doesn't yield explanation. I mean, Richard Feyneman did make noises along those lines. Famous twentieth century physicists never been others. He said, uh yeah, he's got a great quote somewhere. He says, you know, you want to understand, you know, what reality is like, go ask a philosopher dripping with this. You're saying, physics doesn't give you that. Physics gives you these sophisticate instruments or devices in the form of theories, powerful mathematics, mathematized theories that are predictively successful, and that's it. But most scientists, in my experience, they are you know, scientific realists. They think that the things that we're probing are really out there. I mean, the reason that I'm a particle physicist and not a mathematician is that I want to know what's really out there. I think of myself was revealing the truth. And when I'm at cern if I ask people, hey, do you think the Higgs boson that we discovered is real? Or is it just something in our models that let's accurately predict experiments, most of them would look at me like I'm crazy, you know, like I had something bad for lunch. It feels to me like they're doing philosophy by rejecting the question, even though they don't imagine they're doing philosophy. Why do you think that's sort of the natural position of most physicists to imagine, you know, a strong philosophical argument and um that everything we're out there is actually real. Why do you think that most physicists don't consider the whole spectrum of philosophical positions there? I think because it's a sort of natural or default human inclination. First of all, to be a metaphysical realist in the in the minimal sense of there is a way the world is subjectively speaking, and then to go beyond that, to think if we have powerfully predictively accurate ways of describing the patterns of our experiences. Then those must correspond to something objective. If I'm being very vague here, but something in reality is accounting for the fact that our inductions are successful. It may not be a perfect isomorphic overlap right between what we say, either in common sense predictions or categorizations, or even in high level theory, but there's some degree of congruents um there. We're tracking. I guess with what I'm trying to say, we must be tracking something real. And then when you think about fundamental physics, because it's going so deep into the foundations, the inclination, I guess it becomes natural to think we're getting closer and closer to it isomorphism. The categories we're using are are are tracking very directly these entities. But it feels something more squishy than we usually find in physics. You know, physics, we have math and calculations and these sorts of things. Here we're talking about like a feeling that what we're seeing out there is real, and you know, our ideas about the universe must be real. It feels a little bit more susceptible to you know, cultural bias or parochialism, or thinking the way people have always thought. To me, one way to make sense of this question, to make it a bit more concrete, is imagine a scenario like we meet alien physicists and we talk to them about the universe. If what we're learning about the universe is real in a sense that it's not just biased by our human conception, then we can imagine maybe they have discovered the same things. They also found the Higgs boson, and they have group theory as a foundation of their description of the fundamental particles. But if it's not, if instead we have some human element to this understanding, or that what's out there has no relationship, you know, to the model that we've built other than that it works, then maybe aliens would have completely separate ideas about physics. You think that's a reasonable way to frame this question of whether what we're probing is real, whether it could also exist in the minds of other intelligent creatures. Sure, I mean imagine first of all that at some stage in physics, um clever theorist story able to come up with two very different ways of categorizing phenomena, but they were equally predictively successful. Then I think the natural conclusion we would all draw, as it's underdetermined, at most one of these, if they're incompatible frameworks. Uh, at most one of these is true. Perhaps neither. Um we need more information. But one of the great, of course achievements of physics has been to increasingly try to break away from a narrowly provincially human way of looking at things. That's very difficult to do. And at some point I expect we'll come back to this. I think there are limits to how far one can go with that rationally, because at the foundation of the evidence for scientific theories, right the epistemology of science, are scientists in the activity of science. And we can't end up endorsing frameworks in which we cannot locate the rational inquirer in the community of inquirers and there and the activity of inquiring. And I have questions. It's very challenging. But you know, some of the more speculative attempts to unify fundamental particle physics and you know, large scale cosmology, I worry that they they're udding up against, um, these kinds of limits that they're they're positing models that we could imagine for some entirely disconnected reality. Right, they're perfectly coherent models for describing something, But could they describe our reality? Could we have reason to believe? Right? You know, there there, we are right in that question. Could we have reason to believe that we inhabit a world correctly depicted by this model? There's a tricky question there at the limit. It's certainly interesting to wonder about whether humans can imagine what humans can't imagine, right? Can we think our way out of our own box? It's it's certainly unknown. I'm really curious about the point you made earlier about whether there could be alternative and completely functional descriptions of the universe that are conceptually different. Like if I describe the universe with my theory of everything and it has squiggles in it, and I say, look, my theory works, squiggles must be real, and you know, you have your theory and it has squaggles in it, and you're like, no, squaggles are totally different from squiggles, and my predictions are just as good as yours. Then you're saying, we're faced with a question, are squaggles real? Are squiggles real? Is anything actually real? Is that the basic idea. And doesn't that sound very similar to the current situation about the nature of fundamental particles and the questions about quantum mechanics. Right, we have very very different conceptions of like what is real at the smallest scale, relational quantum mechanics, boney and mechanics, all apart from the you know, sort of orthodoxical Copenhagen interpretation, aren't we sort of in that situation. None of those theories give any real variation in their predictions, but they have completely different stories about what's happening in the microscopic scale. Does that mean that nothing is real or just that we haven't found which one is real? I think the latter, that we haven't found which one is real. And of course you're the expert here, not me, But I like to chat with the philosophers of physics and the occasional particle there theoretical physicist about the conceptual challenges in in quantum mechanics and in unifying quantum mechanics with space time theories, and so as I'm told. For example, so you've got this Bowman interpretation, one interesting feature of which is it's a deterministic theory about the dynamics of the universe, unlike at least a couple of the other leading theories. Whether or not we call many universe theory a deterministic theory is a somewhat subtle question, I think. But I'm told that while these four frameworks all have the same predictive consequences for the kinds of experiments we can do now or have done, that, there are in principle Bowman mechanics could have um different predictions, and so we could potentially, I don't know how far off this might be, but we could potentially have evidence that bore differentially between bow Mean mechanics and at least some of the alternatives. So that suggests, yeah, we don't know. So then we're just right currently, you know. But we're still interested in the question. It may not upen in our lifetime. So the question is should we be completely agnostic? And here the different theories have different kinds of theoretical virtues and vices. Insofars, one is willing to say purely general characteristics of theories in terms of simplicity of ontology and things like that, or whether it makes you requires you to make certain very outlandish seeming hypotheses, whether you give that any kind of evidential weight at all might determine whether or not you think we have reason to lean in one direction or the other, even if we don't have conclusive evidence. Well, I hope that experimentalists are clever enough to come up with ways to test these various hypotheses and tell us what's actually happening at the smallest scale one day. So I have a lot more questions for you, especially about emergence. But first let's take a quick break. All right, we're back and we're talking to Professor Tim O'Connor, philosopher of science and follow upon, Grand Champion of the World, who's answering my naive questions about philosophy of science and whether we can understand what's out there and whether it's real. I first came to read your work because I was very interested in the question of emergence cases where we can describe things we see in the world using rules that are very different from the rules of the underlying bits. It's like if you have a set of rules for how legos work, but once you put the legos together into complicated objects, you're better off describing their behavior in a new set of rules, like in a game of life where simple objects with simple rules come together and very complex behavior emerges. How would you define this concept of emergence and why in your views? Emergence and important question in philosophy of science. Yeah, so it's always been a controversial idea, and it emerged in the nineteenth century people began thinking, uh, in emergence terms of it's it's a question about the relationship of science at different levels of grain. So, how does physics relate to chemistry, chemistry to molecular biology, biology to organismic biology, and and so, and then our biology to human psychology neuroscience and the brain to human psychology. And the emergent test is a person who, in very general terms thinks that organization of certain kinds gives rise to new features, new new patterns that have a certain degree of autonomy with respect to the lower level underlying dynamics. It's a new form of dynamics of patterns that the kinds of concepts you need to describe what's going on are different than the kind of concepts you need to do the lower level science. And uh. Left at that um that there is emergencies entirely uncontroversial. There is such a thing as chemistry, and chemistry can be understood to a degree, at least at an elementary level apart from quantum mechanics, and certainly biology can be understood without knowing anything about quantum physics and psychology, you know, you one can even do psychology of various kinds, of social psychology, of normal psychology, and so on without knowing anything about physics or chemistry. So there are patterns in the world that have to do with organized systems of a certain kind, robust patterns, patterns where you can predict phenomena. I mean, think about the fact that if I were to go agree to fly out to California to meet up with you, and three days later I show up at your office door, and you quite confidently believe that that's going to happen, And that involves the movement of a hunk of matter that's coalesced in a fairly organized way, transporting itself across a great deal of distance. And could you predict that in terms of physics, Well, certainly not, given your and given our computational limits. Right, But you know, psychology works beautifully well, right, I mean, we can predict human behavior to a certain degree just by attributing to people beliefs, desires, intentions, uh, and so on, and you can be completely ignorant. People were doing this a thousand years ago, knowing nothing about the physical, underlying physical structure of the world. So there's a sense in which it's it's obviously true that there are emergent phenomena. So weak emergence is the uncontroversial kind. Weak emergence says there are organized phenomena that have their own characteristic forms of activity, their own characteristic features, and the kind of dynamics for how how this activity unfolds. But the weak emergentis says all of that is fixed, in some sense determined by the underlying most fundamental dynamics in our world, the fundamental physical dynamics, whatever that turns out to be, you know that lies at the root of everything. Fix that across space and time, all the fundamental physics, right, and you've thereby fixed all higher level phenomena in their patterns. So, for example, like we're playing a game of ping pong, or saying that we can describe the motion of the ping pong ball using fairly simple rules, but fundamentally, even though we can't calculate it today, those basic rules of the ping pong ball come from the basic rules of its constituents. That the twoing and throwing of all the particles inside the ping pong ball adds up somehow to F equals M A that is determined by the basic elements. Is that is that the idea? Yes, And it's just you know, computational limits on our part that we can't discern it all right, So laplace the nineteenth century physicist mathematician, you know, famously imagined a kind of disembodied intelligence who had with subjects eurocomputational limits, right, could track all the fundamental entities constituting space and time and their trajectories, and discern the patterns the fundamental dynamics that drive those things their interactions. And then the thought is you could, so to speak, step back, uh and see the forest for the trees, and could also notice then that there are these structured uh features of of you know, more larger regions of space and time and their interactions, and and discern they have dynamics, and could in a very lorious way for us at any rate, show that these high level patterns don't disturb you might say, or add to what's going on at the fundamental level, they're just a structured consequence of it. It's a surprising fact why we could imagine a boring flat world where there's just fundamental physics but there was no interesting structured phenomena um, while our world is not like that. And so that gives rise to an interesting question even for the weak emergence. So why is our world such that there are not just fundamental physical patterns that fix everything, but also these higher levels structured phenomena. It seems conceivable that that there could be alternative physics where that just never happens. So to me, that's a that's a really fascinating question. I can't let you go past that without exploring it more deeply. To me, that's one of the deepest questions. Like in the weak emergent case, where everything is determined by the most fundamental principles, why is it then possible to find this structure? Why is it possible to find fairly simple mathematical laws with hugely reduced degrees of freedom? Right when you talk about the ping pong ball and moving across the table, you don't have to talk about all the particles that are inside of it, as you say, there are these simpler descriptions of structure that emerges. Is it necessary that structure emerges? Why isn't it just the fundamental bits and then basically chaos above that? You know, Why isn't everything like a hurricane out of rain drops and possible to predict no larger structure? Why does it these simple explanations emerge. Do we understand that? To the best of my knowledge? And no, since I've never encountered anyone the many thinkers, scientists and philosophers who talk about emergence who directly address that question and give kind of a full, plausible sounding answers to it. And I'm almost thinking it's a question for a mathematician or a physicist, you know, kind of where's dual hats? As a mathematician, I mean, so you you invoked the game of life. So John Conway, famous mathematician, Uh, he described this the cellular automata, which sounds complicated, but it's actually quite simple, right. It's like it's almost like describing a reality, a two dimensional reality that has very very simple property, so simple, much simpler than fundamental physics. But what's really interesting about it is he shows that depending on the initial conditions you said, and then you just watch how grid changes over time. Moment to moment, patterns emerge, Structured patterns emerge that don't alter the basic rules of life are unchanged, and yet there are these interesting patterns that can be understood in their own terms. That way of framing at this very elementary mathematical he should he shows it that it happens in certain life worlds. You get these interesting patterns, and then the question is whether it's almost sounds like the territory of a mathematical proof of certain fundamental dynamics subject to certain constraints that can be given a clear mathematical description, necessarily will yield over um, given enough times, patterns of structured interactions. At least, That's why I'm tempted to say it's it's it's almost it's that kind of question. It's fascinating to me. And you know, maybe, like the weakest argument I could make to say that structure has to emerge is that, well, maybe it doesn't a is, but we exist in the universe where it has, because otherwise we couldn't. I mean, we are structure right my mind, my concept of myself, this conversation all of this is emerging structure. I'm not a fundamental bit in the universe. Neither you neither as humanity, maybe not you know consciousness, So perhaps you know there are many universes out there, and only in ones where structure does emerge at larger scales can you have consciousness and podcasts and philosophy at those scales. That seems to be sort of a very weak argument. In physics, we have another concept, which is normalization theory, which lets us say the theory we have about particle physics right now is an effective theory. We know that we know that electrons and quirks are probably not the answer to the deepest question in the universe. But we can abstract away all the really high energy stuff, the stuff we can't probe today, the smaller bits in terms of a few parameters, and Robert Wilson theory about renewalization and all of this stuff and the decoupling theorem lets us do this. But we don't really understand to my knowledge why that is. It seems to it's sort of like science and a larger scale. It seems to work. We have these abilities to do this, but there's no theory as far as I can tell, that tells us why that happens. I mean, it's in another way, if I gave you a fundamental description of the universe, could you predict whether or not emergence comes out of it, whether or not things emerge, or would you have to run the simulation and observe it. To me, that's a really interesting question. You know, why this stuff emerges at all? Yes, And then of course there's the question of a different kind of emergence. So strong emergence, which is non trivial, it's not trivially manifest, is a notion of when under certain structured conditions, properties of holes arise and they have an influence on how things behave. And these properties do uh add at the end of the day, and they add to the fundamental dynamics of the world. They have a kind of downward influence, and it goes all the way down right. So it's as if it's a new force, like property or something. I mean, how exactly we might theorize such an irreducible property, irreducible but causing the effective property. Perhaps there's more than one way we could do it. But you know, just as a kind of rough and ready initials start. You know, think of it as like a new kind of structured force property or something that adds to But this is sort of a shocking idea to me, because as a particle physicist, I imagine a reductionism works. If I want to understand big stuff, I go to the small stuff, and I eventually I can build up from there if I have infinite computing power, etcetera. And you're suggesting that's not necessarily the case, that maybe there are rules that exist at the higher level, of the level of ping pong balls and ice cream, that don't come out of the smallest bits, but somehow exists only at that level. Is that right? Yeah? And and so then I want to say, you know, it's an empirical question. It ought to be thought of as a straightforwardly empirical question whether there are emergent properties of that kind, emergent properties and patterns and activity of of that stronger variety. And for that I don't think fundamental physics is the domain you go to, or certainly not by itself. I mean, if we were Laplasians, pure disembodied infinite intelligence, well we could we could do do it and say, well do it do I is there any region of space time we're running only with the fundamental dynamics breaks down right in certain interestingly structured local regions, right, But we're not such an intelligence and so and it's inconceivable at present and probably forever, that we could directly monitor in real time trillions upon trillions of variables corresponding to all the particles both in and immediately within the light cone over an interval of time, you know, some some sort of organized phenomena and calculate, you know what, how we expect all those interactions to go and see whether the particle physics is sufficient for capturing what's going on in say a human brain, to pick a likely target of a strong emergences hypothesis. Right, And so that's a very attractive question obviously. You know, we look at the human brain and it's a lump of stuff. There are other lumps of stuff that don't seem to be conscious. You know, my desk, my chair are also lumps of stuff to have actually the same you know, number of protons and neutrons and electrons as my brain does. Why is it that my brain exhibits this crazy behavior that rocks and chairs and tables don't. So are you suggesting that, for example, consciousness might not just emerge from the interactions of those pieces inside the brain, but could come out at some sort of higher level. Yeah, and so here's where I would say, contentiously, we're kind of in the realm of philosophy. But when you reflect on the nature of conscious experience, we seem directly acquainted with qualities. Qualities of our own experience says that cannot plausibly, perhaps even conceivably be mapped onto structured properties of the relevant regions of our brain. So you know, famous kind of example, if you if you go into the philosophy literature talking about this, you encounter the story of this neuroscientist Mary, and Mary is we imagine a hundred years from now the science of the neuroscience of color vision is complete, and uh so Mary is a credential neuroscientist of color vision. So what that means is you put somebody on an under the relevant scanning device and Mary gets some kind of interpreted feed out from from her computer telling her what's going on structurally, and she can predict what kind of color experience the person is having just on the basis of that But now here's the wrinkle you add to the story. Mary herself is ever had color experience because Mary Mary's parents were crazy psychologist who thought it was an interesting experiment to raise her to be both a scientist of color vision, but to never have So she only has monochrome shades of gray, right everything. And she's locked in a room and she she does there's nothing that has color beyond shades of gray and white and black. She's never cut herself, She's happily has never cut herself. She never thought to do that. But one day, you know, she escapes from her room and she looks out on a bright sunny day and sees a red rose. And she knows that when human beings look at roses right, that they have what she calls red color experience. But for her, it's a purely theoretical quality. What is that the way red looks to a normally sighted human under bright, sunny conditions. So now she has the experience, and she says to herself, so that is what a red rose looks like. That is she's not learning something about the color of the rose. That's that has to do with the surface of the rose. Right, kind of certain reflectance property. That's not what she exclaims. She's actually talking about her own experience of a red rose. She's saying, that's what an experience of redness is like for a human being, you know. And we think about that thought experiment, and we think it makes perfect sense, and we say, right, somebody who who's never experienced the color red, you can't commune. It's kind of ineffable. There's just this simple quality, right, of a certain kind of deep red color, let's say, as opposed to a blue and green. Right, These are just they're just different. They're distinct qualities, but the relatively simple qualities of our experiences right now. That the physics of it, of course, is that photons hate your eyeballs at different energies, different wavelengths, and they'll stimulate, you know, different paths at different signals of the optic nerve. But of course there's no color in those signals. Right. The color you're saying is experienced by the brain. It gets the signal and it gives you the experience of red or the experience of blue. You're saying, that internal experience. We don't know how to describe it, or quantify it or make it objective, but but it's real, and it's something over and about. Mary seems to learn something new about color experience, even though she knew every what you were just describing in shorthand. Harry knows all that stuff. She she knows the neuroscience of color experience. She knows what goes on in the visual cortex. Right, what kind of patterns of firings of neurons are going on when someone has an experience like that? Right, But those seem to be all the causal preconditions, the underpinnings of color experience, but not the experience itself, the subjective of the simple subjective quality. So the suggestion is right, there are these subjective qualities, qualities of conscious minds, experiential qualities, but are something over and above the physical structures and states and processes that undoubtedly our nest necessary to have to undergo those experiences. There's something additional. They seem strongly emergent, because now we're not just talking about a pattern of activity. We're talking about a new fundamental quality that can't be described in terms of any of these sorts of processes, even at the neuroscientific level of description, which would seem to be the relevant level of description here, right, that's if it is a wholly physically constituted phenomena, then neuroscience should be the science that tells you what it is. It's that neural structure and patterns. So you describe this as an empirical question, what is the empirical test you could do to figure out whether consciousness or you know, even physics of baseballs is strongly emergent or weakly emergent, whether it is something new at these larger scales, or whether this is determined by the little bits that they're made out of. Right, Well, it would seem like we would need a much you know, neuroscience is still in its RelA to infancy. If you talk to neuroscientists, that's what they say about the state of the science. They know a lot about local interactions and so on, neurons and synapses and all that, but large scale patterns um is something that they're just beginning to get a bit of a handle on. There's a ton that they don't understand. But it would seem like if we could envision a much more developed systematic neuroscientific theory of neural dynamics of brains as complicated as our brains, and you could show that you could completely predict the unfolding of the relevant processes, say in the visual cortex, when someone's having color experience, without recurse to some hypothesized further quality that presumably would be doing something. That is, if the look of a red rose really is a quality over and above some kind of structured neural quality, then that quality is part of what leads me to talk about it. Right, So that means that in principle, a neuroscientist who's paying attention in real time what's going on in your brain when all this is happening, you're having experience and you're talking about it, if the theory was sufficiently well developed and testable, could see whether somehow there was an incompleteness, you know, if the if the neuroscientists just just doing it in terms of neurons and neural assemblies and so forth, and they can perfectly predict the dynamics going on in the relevant portion of your brain without recourse to some further hypothesized, holistic, strongly immersion property. But in fact, suppose suppose that's just wrong. It's an illusion, but it's somehow hardwired into us that we have this illusion. If there's something further that's left out of a physical description that's a conceivable, you might say it's a psychological hypothesis. Right, one could go looking for there's something about the way our our psychology structured such that you know, you know, we know there are visual illusions built into our visual system, the Mueller lie, the you know, the two lines with arrows. I won't go into a description right there, there's well known visual illusions that have to do with certain limits to our visual system. Right, we're led to say untrue things about what we're experiencing. Maybe maybe there's something like this that's even deeper. Right, we're inclined to attribute qualities to experiences that aren't actually there, right, and so if they're not there, then boom, the problem goes away. Okay, great, So so you know a scientists, you know, who's kind of reductionist minded should be tempted by this illusionist perspective unconscious experience. We're having experiences, it's just they're not what they seem to us to be. And to me, that connects really deeply with this larger question of what's out there? And do we know that what we are experiencing, the theories we're building from those experiences really reflect what's real in the universe, or whether it's just us to sort of game we're putting together in our minds, um And so I want to ask you more about that, but first let's take another quick break. Okay, we're back and we're talking with Professor Tim O'Connor, who's telling us about how things emerge in the world and how we can explore them and most importantly, what that tells us about what's real out there in the universe. And to me, this question of emergence is very closely connected to the question of scientific realism, because even if you believe that the universe is real and there are basic bits and rules about those basic bits, if you take the weak emergence, we haven't learned what those basic bits are. We've only learned the emergent bits. So in the question of scientific realism of what's out there in the universe, how do we know that what has emerged is real or whether it's just sort of like our description of it. Even if there is a real un verse out there, and if we drill down with the biggest particle collider or anybody could ever build. We might find something deep and true. How do we know that what's emerged on top of that is real? Is it possible that the way things emerged to us might be different than the way things emerge to another intelligent race that is a different set of senses, For perhaps it perceives the universe through different fundamental physics properties. How do we know the emergent pieces themselves? We can you know, say, are actually out there? Good? Um? Right, so it seems, you know, in the abstract, it seems conceivable that there be different but equally effective course scrained ways. You might say of chunking up you know, things that the level of middle sized objects and observers, But just the categories are different. Um, so you know, we find it natural to group things. Let me acknowledge right at the outside, or I think we all should acknowledge our senses, right, Our categories are closely tied to our perceptual senses, and our senses are geared to be good at we know detecting features that are useful to us, or at least we have reason right to believe they would have evolved. And so you know, this could kind of add scientific reason to be a little bit worried about this question. It say, certain things get foreground in our experience because they they're really important to us. You know, colors are signals to us of you know, food sources and properties for example, and probably a lot of other things I don't even know about. But maybe to a different kind of a non carbon based kind of inquirer who doesn't need organic food sources, maybe color might not be the same same sale sort of property, but other properties that do have relevance to its survival and its ability to navigate its environment would be foreground. And for us, we don't kind of see, we don't. We don't tend to pick out those patterns, and so it leads yeah, and then you know, you generalize the picture. And then so then the two different types of enquirers, the organic ones like us and the non organic silicon based ones that we could imagine their whole way of representing middle sized environmental features and patterns somehow different, but they get along well in their environment that they're able to do science. And so suppose we're at roughly the same level of scientific advancement, and so we have rather similar fundamental physics, but we're different. Maybe that's what you're asking, you know, at the at the level of kind of more emergent levels. But there's also there's a question here a scale, because when we talk about emergence, I think you're probably thinking about me and you and ice cream, ping pong balls. But for the particle physicists, I'm even talking about electrons. I'm talking about corks, which we think are probably emerging from something you know, mind bogglingly even deeper in the universe. So basically everything we've ever learned is emerging. We have no knowledge of the fundamental and we don't even know if there is something fundamental. Maybe there isn't Maybe it's a infinite tower of effective theories all the way down. There is no deep truth. How do we know that our tower will line up with alien towers or if they have another way of looking at what you call coarse grained theories of the universe where to me, course, grain could be as small as an electron or as large as a planet. Yeah, I don't know if this fully Uh, it certainly doesn't fully address your question, but I would want to throw out the following constraint unless we become complete systematic skeptics about human knowledge and say, you know, I don't even know whether or not I'm dreaming, or even more radically, you know Descartes way back in the seventeenth century, perhaps perhaps I'm just a disembodied mind and I have a false beliefs about my own past. In fact, there is no physical world. I wasn't born, none of this, and there's just some evil genius spent on deceiving me who's pumping my mind with a flow of stream of experience that I naturally interpret as my in interacting with my physical environment. But none of it's there, right, or you know the matrix films, you know, our kind of updated version of this, you know the way things really are, that what really lies behind our experiences is something very different from what we naively take it to be. Well, you can't do science under those ground rules, right. Science has to presuppose, for example, that we didn't pop into existence just thirty seconds ago with a bunch of you know, built in false memories about having had past experience. Science has to presuppose that there's some kind of regularity to the way the world unfolds. And if you say, well, no, science can show that there's regularity by doing experiments and you know, corroborating results. That presupposes that what you're hearing when you're being informed by another scientist about their results itself reflects the um outputs of another scientist. But why are you trusting your senses? Right? That's a really big assumption. That your senses are even effectively registering anything outside you is a big assumption. Well, you can't scientifically verify that, right, because you'd have to somehow get outside of your senses. You can't do that. You can't get outside of your rational thinking. So the point is, even what we think of as a paradigm of rational inquiry, science has to make certain foundational assumptions about the rough and ready, at least reliability of our basic cognitive equipment, and the rough and ready predictability or patterned nous of the world that we're seeking to describe. It doesn't have to assume a lot more than that, but it doesn't have to assume at least those things. And it has to assume if science is going to deliver a rational set of beliefs of us, that we exist, that we persist, that we really are interacting with one another. Well, but once you once you do that, when now we've got I exist, you exist if we're fellow scientists, I'm part of this community, just this distributed community. I have to assume, since I can't do all the science myself, no scientists can do that, that there is this rational community that's effectively managing to communicate results and theories and descriptions and how they corroborate with theories. A lot is getting baked in my point. I guess that is what I'm getting at here has to be baked in for Steve and ask an interesting question about have our theories delivered the rational goods? Now? Making those assumptions doesn't require that. Chemistry or biology as we know it is very closely tracks the truth at that level of description. So I'm not suggesting we get our emergent phenomena. But there there are constraints. You can either be a total skeptic or you have to say there are enquirers that have certain capacity of these and uh certain reasonable assumptions that they make. I'm not sure how far that gets us, but it gets us a certain ways. I think you're making the point that we can take our skepticism and paranoia too far in throwing out everything and saying we can know nothing, um. And it's certainly the case that, you know, we would like to know something that's true about the universe. But I think the motivation for examining these fundamental in the foundations of our knowledge and how we know things is because we wonder if we've make it made a mistake, if we've made some arbitrary choices where we could have perhaps if Plato had a different mood, you know, founded intellectual thought in another direction, and everything would have been built up and conceived up in a completely different way. And to me, that's what's exciting about potentially meeting alien physicists, or even digging back into ancient human knowledge and seeing how independent communities the Mayans, the Egyptians of Chinese thought about their the universe and their relationship to it, you know, separately from from each other. Because it seems to me like it's possible, and it's fascinating to me that it's possible that the way we've built our ideas of physics and the universe could have some arbitrary nous to it, right, that there could be another way to have done this. So to me, it's exciting to probe those and to do the impossible thing that we suggested earlier, which is to imagine what humans haven't yet or maybe cannot yet imagine. So let me ask you the last question, what do you think are the prospects for making progress? I mean, we've been talking about whether the universe out there is real or just imagined since the matrix, since um, you know, the card, since Plato in fact, so it's been thousands of years we've been thinking about these questions. Is it a question we'll be thinking about forever or are we likely to see breakthroughs where one day we say, oh, look we settled that question. Plato was right or Plato was wrong, and then we can move on to other questions. What do you think, Well, we won't settle it in the sense that, um, there's never the basis for a somewhat reasonable worry or skepticism that we haven't mailed it down. There's always because we're a scientific human inquiry generally, and science as a special rigorous case of human inquiry is fallible. There's no reason to believe they're perfect. So that's if if we lower our sites and uh, get away from having a perfect congruence, a perfect mapping of reality. Maybe we'll never get that, but we have a closer and closer mapping than that. That's good enough. Well, it certainly is helping us, you know, develop new technologies and I hope revealing something that's true about what's out there in the universe. To me, I love these moments of insight and discovery where we feel like not just that we've developed some new tool that describes the universe, but we're actually revealing its internal it's underlying mechanism. You know that the ex boson, for example, is actually out there and is doing and frowing and doing. It's a bit to create mass for all the other particle and not just a mathematical description that we have in our heads, because otherwise my entire life's work is uh, it's just much more theoretical than I ever imagined. But thanks very much for joining us on the podcast today and for thinking about these crazy questions and allowing me to talk about aliens and philosophy at the same time. I really appreciate you coming on the podcast. All right, Thanks Daniel, thanks for having me, Thanks for listening, and remember that Daniel and Jorge explained. The Universe is a production of I heart Radio. For more podcast for my heart Radio, visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.