WEBVTT - Why does physics even work? 0:00:08.800 --> 0:00:13.320 Science seems to work. We can argue about the philosophical 0:00:13.360 --> 0:00:16.360 foundations of it, and whether a photon is a particle 0:00:16.560 --> 0:00:19.279 or a wave. We can wonder whether the universe that 0:00:19.400 --> 0:00:22.880 we perceive out there is real or is just an 0:00:22.880 --> 0:00:26.439 elaborate hoax like in the matrix, and how we might 0:00:26.560 --> 0:00:30.120 ever know the difference. But in the end, what is 0:00:30.200 --> 0:00:34.800 beyond question is that science does work. We can build 0:00:34.840 --> 0:00:39.199 airplanes that almost never crash. We can build incredible miniature 0:00:39.240 --> 0:00:43.159 devices that rely on the quantum properties of electrons. We 0:00:43.320 --> 0:00:47.720 can and have sent robots to crawl over the surface 0:00:47.800 --> 0:00:51.080 of other planets and send us back pictures. All of 0:00:51.080 --> 0:00:54.960 this stuff works because of science. Science lets us build 0:00:55.000 --> 0:00:59.040 and test and refine little mathematical stories about how things work, 0:00:59.080 --> 0:01:03.240 and then calm definitely use those mathematical principles in totally 0:01:03.280 --> 0:01:06.600 different contexts. Ideas that we have in the shower, then 0:01:06.680 --> 0:01:10.839 test in basement labs. They all work inside your iPhone 0:01:10.840 --> 0:01:14.720 and on the space station. We can confidently use what 0:01:14.800 --> 0:01:19.000 we have learned, even if we aren't exactly sure why 0:01:19.200 --> 0:01:40.120 science works and whether the universe out there is actually real. Hi, 0:01:40.360 --> 0:01:43.520 I'm Daniel. I'm a particle physicist and a professor at 0:01:43.560 --> 0:01:47.040 UC Irvine, and I want to know what's real about 0:01:47.040 --> 0:01:50.480 the universe. I don't want to just have ideas that work. 0:01:50.680 --> 0:01:53.920 I want to know the truth about the universe. And 0:01:54.120 --> 0:01:58.040 welcome the podcast Daniel and Jorge Explain the Universe, where 0:01:58.080 --> 0:02:01.560 our goal is to do just that, to explore with 0:02:01.680 --> 0:02:05.240 you what we do and don't know about the universe, 0:02:05.400 --> 0:02:08.840 how microscopic little particles interact at the smallest levels, and 0:02:08.840 --> 0:02:12.119 how all of their twoing and frowing and buzzing weaves 0:02:12.160 --> 0:02:15.519 itself together into the world that we know with very 0:02:15.560 --> 0:02:18.240 different rules, which is just a small part of the 0:02:18.320 --> 0:02:23.240 larger context of stars and galaxies and superclusters slashing around 0:02:23.280 --> 0:02:25.720 in a web of dark matter to make this glorious 0:02:25.760 --> 0:02:29.040 and crazy universe. My co host and a friend, Jorge, 0:02:29.160 --> 0:02:32.000 is on vacation this week, so I'm taking the opportunity 0:02:32.120 --> 0:02:35.160 to take a bit of a digression into the philosophy 0:02:35.240 --> 0:02:39.200 of science, together with an exciting guest. Now, what's amazing 0:02:39.240 --> 0:02:42.919 to me about science is that we are capable at 0:02:42.960 --> 0:02:46.720 all of understanding the universe that jumped up apes with 0:02:46.760 --> 0:02:49.839 tiny little brains on a little rock in an irrelevant 0:02:49.880 --> 0:02:53.360 galaxy can just by doing a few experiments and writing 0:02:53.360 --> 0:02:57.280 down some math symbols build a mental model of how 0:02:57.320 --> 0:03:01.040 the universe works, and a model that seems to work 0:03:01.120 --> 0:03:04.760 pretty well. This model has revealed how stars form, and 0:03:04.960 --> 0:03:09.160 how the universe expands, and how electrons funnel through weird metals, 0:03:09.200 --> 0:03:11.920 and how the whole universe is filled with an invisible 0:03:12.000 --> 0:03:16.480 Higgs field that gives matter to microscopic particles. It's incredible 0:03:16.520 --> 0:03:19.520 what we have learned about the nature of the universe. 0:03:19.639 --> 0:03:22.120 The very fact that you are hearing this podcast right 0:03:22.160 --> 0:03:26.040 now relies deeply on our understanding of the basic rules 0:03:26.080 --> 0:03:29.600 of the universe and our ability to manipulate and rely 0:03:29.840 --> 0:03:33.920 on them. But why is that possible? Why does it 0:03:34.040 --> 0:03:36.960 even work? Because what I said a moment ago was 0:03:37.040 --> 0:03:39.920 a bit of a stretch of the truth. For all 0:03:39.960 --> 0:03:43.560 of the successes of particle physics, we don't actually have 0:03:43.680 --> 0:03:47.000 an understanding of the basic rules of the universe. We 0:03:47.040 --> 0:03:50.160 don't know what the basic bits of the universe are 0:03:50.480 --> 0:03:54.120 and what their rules are. Are they strings? Is it 0:03:54.160 --> 0:03:57.640 a quantum foam? Is it something completely different than we 0:03:57.720 --> 0:04:01.320 haven't yet or maybe could never even imagine or grapple with. 0:04:01.480 --> 0:04:03.800 What we do have is a set of rules that 0:04:03.840 --> 0:04:06.680 work for the experiments that we can do, but we're 0:04:06.720 --> 0:04:10.120 pretty sure it's not the final answer, not that they're 0:04:10.120 --> 0:04:12.640 wrong and it's all a hoax, but that it will 0:04:12.680 --> 0:04:17.000 be eventually replaced by a deeper understanding. The way Newton's 0:04:17.080 --> 0:04:19.880 physics worked for the experiments that could be done in 0:04:19.960 --> 0:04:24.320 his day, but we're later replaced by Einstein's more general theory. 0:04:24.760 --> 0:04:27.320 The way you can use F equals m A to 0:04:27.360 --> 0:04:30.200 calculate how a ball flies through the air, and it 0:04:30.279 --> 0:04:33.800 certainly works even if you don't understand the quantum frothing 0:04:33.920 --> 0:04:36.719 happening inside of it. What we have in particle physics 0:04:36.800 --> 0:04:40.159 is the same thing. We don't think it's fundamental. We 0:04:40.160 --> 0:04:43.080 don't think it describes the basic bits of the universe. 0:04:43.240 --> 0:04:46.760 We think it's effective, meaning that it works, but it 0:04:46.800 --> 0:04:51.680 describes things that emerge from the fundamental pieces. But it 0:04:51.760 --> 0:04:54.680 still works even though we don't know what the basic 0:04:54.720 --> 0:04:57.200 pieces are and the rules that they obey. We have 0:04:57.360 --> 0:05:00.440 found the non basic pieces and the rules that those 0:05:00.560 --> 0:05:04.719 non basic pieces obey. For example, we have rules of 0:05:04.760 --> 0:05:08.520 economics and they mostly work. But people and money are 0:05:08.560 --> 0:05:11.719 not fundamental elements of the universe. You can have a 0:05:11.800 --> 0:05:14.799 universe without people and money, and most of the history 0:05:14.800 --> 0:05:18.040 of the universe didn't have people or money. But once 0:05:18.120 --> 0:05:21.320 people and money emerge, you don't have to describe the 0:05:21.360 --> 0:05:25.599 economy of a country using particle physics or string theory. 0:05:26.160 --> 0:05:30.040 You can find basic mathematical laws that describe economics and 0:05:30.120 --> 0:05:33.240 are pretty simple, just like F equals I may is 0:05:33.279 --> 0:05:37.600 pretty simple, but it ignores all of the quantum details underneath. 0:05:38.080 --> 0:05:41.240 So why does that work? Why is it possible? And 0:05:41.279 --> 0:05:44.960 what does it mean about whether what we have learned 0:05:45.120 --> 0:05:49.560 is true and fundamental to the universe, a real description 0:05:49.600 --> 0:05:51.640 of what's out there, or if it's just a set 0:05:51.640 --> 0:05:55.200 of mathematical stories that humans tell ourselves that happen to 0:05:55.279 --> 0:05:58.279 work very well. So today on the podcast, we'll be 0:05:58.320 --> 0:06:07.279 asking the question why does physics even work? Why is 0:06:07.279 --> 0:06:11.240 it possible to tell mathematical stories about the universe out 0:06:11.240 --> 0:06:15.360 there without knowing the deepest underlying truth. We know it's 0:06:15.400 --> 0:06:19.200 possible to make chicken soup and iPhones without knowing quantum gravity, 0:06:19.360 --> 0:06:22.480 but why can we Does that mean that the stories 0:06:22.560 --> 0:06:25.200 we are telling, the physics ideas we have developed are 0:06:25.240 --> 0:06:29.000 not real in some deep, true sense. Would alien scientists 0:06:29.040 --> 0:06:31.320 come up with the same theories or have a different 0:06:31.480 --> 0:06:34.920 concept of how to describe the universe. To help us 0:06:34.920 --> 0:06:37.520 probe these questions, I've invited an expert in this area, 0:06:37.600 --> 0:06:41.279 Professor Tim O'Connor. Tim is a professor of philosophy and 0:06:41.320 --> 0:06:45.160 cognitive science at Indiana University, where he specializes in these 0:06:45.160 --> 0:06:49.600 types of questions and especially the phenomenon of emergence cases 0:06:49.640 --> 0:06:52.200 where it's possible to describe things at a higher level 0:06:52.560 --> 0:07:05.359 without knowing the underlying pieces. So it's my pleasure to 0:07:05.600 --> 0:07:09.080 introduce to the podcast Professor Tim O'Connor Tim. Thank you 0:07:09.160 --> 0:07:12.120 very much for joining us today. Glad to be with you, Daniel. 0:07:12.280 --> 0:07:14.480 As well as being an expert on philosophy of science 0:07:14.480 --> 0:07:16.640 and emergence, I see that you also claimed the title 0:07:16.680 --> 0:07:20.480 of Philo Pong World Grand Champion or the world's leading 0:07:20.560 --> 0:07:24.640 table tennis player among properly credential philosophers. Tell us about 0:07:24.640 --> 0:07:26.680 how you figure that out? How you determined that you 0:07:26.680 --> 0:07:34.480 could claim that title. Oh, I declared the title, and 0:07:34.680 --> 0:07:38.280 the interesting thing is that no philosophers have disputed that 0:07:38.360 --> 0:07:40.840 I hold the title, and I think the reason is 0:07:40.960 --> 0:07:44.960 that those who like to play serious table tennis figured 0:07:45.000 --> 0:07:46.880 out that. Great. Then all I have to do is 0:07:46.920 --> 0:07:49.280 beat you, and then I get to claim the title. 0:07:49.360 --> 0:07:52.560 So I have defended the title on a few occasions. Um, 0:07:52.600 --> 0:07:55.400 but I expect to be losing the title the next 0:07:55.440 --> 0:07:57.120 time I go back to China. Well, I think it 0:07:57.160 --> 0:07:59.880 made me says something about philosophy that you can just do, 0:08:00.000 --> 0:08:02.120 say yourself champion, and then you know, see, if it 0:08:02.160 --> 0:08:04.480 stands up to scrutiny, that's it. It's kind of like 0:08:04.520 --> 0:08:07.680 a homesteading thing. If no one disputes it, then at 0:08:07.720 --> 0:08:10.600 a certain point that's I own it exactly. So, when 0:08:10.640 --> 0:08:14.040 you're not winning ping pong matches, you're a philosopher of science, 0:08:14.120 --> 0:08:16.559 tell us about that. What got you into philosophy of science? 0:08:16.600 --> 0:08:19.160 What are the most important questions in your mind that 0:08:19.160 --> 0:08:23.000 we should be asking about our universe? Great? Uh so, well, 0:08:23.120 --> 0:08:27.360 I start out and still think of myself fundamentally as 0:08:27.400 --> 0:08:33.280 a metaphysician, where metaphysics asks the really most general foundational 0:08:33.400 --> 0:08:40.199 questions about reality, about fundamental categories like object, property, space, time. 0:08:40.360 --> 0:08:44.080 Does the physics wholly determine what one should think about 0:08:44.080 --> 0:08:48.240 space and time? It certainly constraints, um, what one should say, 0:08:48.320 --> 0:08:50.960 and I'm more in the latter campic constraints, but doesn't 0:08:50.960 --> 0:08:53.720 wholly determine how we think about it. But the relationship 0:08:53.800 --> 0:08:58.160 of philosophy metaphysics to science is a challenging question in 0:08:58.240 --> 0:09:02.120 its own right. And of course the two subjects originally 0:09:02.200 --> 0:09:05.280 refused in the history of Western thought, going all the 0:09:05.280 --> 0:09:08.720 way back to thinkers like Aristotle. But well on up 0:09:08.760 --> 0:09:12.080 to the time of Newton. Um you had a one 0:09:12.160 --> 0:09:16.720 job title natural philosopher, which was a description of science 0:09:16.800 --> 0:09:19.719 as we think of it, as those philosophical questions that 0:09:19.880 --> 0:09:23.640 concerned the natural world. And I think it's beginning with Newton, 0:09:23.880 --> 0:09:28.640 who famously, when pressed for an account or an explanation 0:09:28.720 --> 0:09:33.199 of how his theory of gravitational attraction action at a distance, 0:09:33.679 --> 0:09:36.280 how we could conceive it seemed inconceivable, how we could 0:09:36.280 --> 0:09:38.600 make sense of that, he famously said about you know, 0:09:38.640 --> 0:09:42.480 about that, I feigned no hypotheses. And he's beginning to 0:09:42.520 --> 0:09:45.360 show a certain sort of well, you know, you might 0:09:45.440 --> 0:09:48.400 ask a certain kind of philosophical question, but as far 0:09:48.480 --> 0:09:53.160 as doing science, which is what fundamentally Newton was up to, Uh, 0:09:53.200 --> 0:09:58.080 the theory works beautifully, the mathematics works, it's predictively successful, 0:09:58.200 --> 0:10:00.400 and so he was willing to go with that. So 0:10:00.440 --> 0:10:02.120 I want to talk to you specifically in a bit 0:10:02.160 --> 0:10:05.479 about emergence and how the world that surrounds us arises 0:10:05.480 --> 0:10:06.800 and how we make sense of it. At first, I 0:10:06.800 --> 0:10:08.440 want to start with a bigger picture of why we 0:10:08.480 --> 0:10:11.520 ask these questions. As you say, we see that science works, 0:10:11.960 --> 0:10:13.880 We know that it does. It's the reason that we're 0:10:13.880 --> 0:10:16.800 talking right now. So if Newton doesn't care about questions 0:10:16.840 --> 0:10:19.240 like why does it work? Or you know, is the 0:10:19.320 --> 0:10:21.839 universe out there real or is it just a story 0:10:21.840 --> 0:10:24.240 in our minds, why do we care about those questions? 0:10:24.240 --> 0:10:27.840 Why are those questions important to figure out? Because ultimately, 0:10:27.840 --> 0:10:30.920 I think we were driven to wanting to have a 0:10:30.920 --> 0:10:36.800 consumption of reality on which it's explicable. Uh it makes sense. 0:10:36.840 --> 0:10:39.800 I mean explicable, not in the sense necessarily if involving 0:10:39.880 --> 0:10:43.800 purpose or anything like that, but just rationally explicable. And 0:10:43.960 --> 0:10:50.640 so simply retreating to um an instrumentalist few syite of science, 0:10:50.880 --> 0:10:56.520 UM saying it's science just delivers sophisticated instruments that enable 0:10:56.640 --> 0:11:01.880 you to predict future observations and ultimate control future patterns 0:11:01.920 --> 0:11:06.040 to degree through technology. That sort of conception leaves open 0:11:06.080 --> 0:11:08.240 you know why, but why does it work? It can 0:11:08.320 --> 0:11:14.400 seem like a cosmic coincidence um, that reality exhibits deep patterns. 0:11:14.440 --> 0:11:17.080 If all you're willing to say is there are these 0:11:17.160 --> 0:11:21.439 deep patterns and there's no rational intelligibility behind them. So 0:11:21.679 --> 0:11:25.080 not everyone shares it, but it's the fundamental philosophical impetus 0:11:26.160 --> 0:11:30.320 I guess to want to understand why things are as 0:11:30.400 --> 0:11:35.720 they are. Um, And so depending on one's conception of science, 0:11:35.720 --> 0:11:38.400 science may or may not even give you that right. 0:11:38.720 --> 0:11:43.240 So so there are famous scientists too who insisted that 0:11:43.280 --> 0:11:46.640 in a sense, science doesn't yield explanation. I mean, Richard 0:11:46.640 --> 0:11:50.800 Feyneman did make noises along those lines. Famous twentieth century 0:11:50.800 --> 0:11:55.120 physicists never been others. He said, uh yeah, he's got 0:11:55.160 --> 0:11:57.280 a great quote somewhere. He says, you know, you want 0:11:57.320 --> 0:12:00.880 to understand, you know, what reality is like, go ask 0:12:00.920 --> 0:12:05.559 a philosopher dripping with this. You're saying, physics doesn't give 0:12:05.559 --> 0:12:10.000 you that. Physics gives you these sophisticate instruments or devices 0:12:10.440 --> 0:12:14.640 in the form of theories, powerful mathematics, mathematized theories that 0:12:14.840 --> 0:12:18.440 are predictively successful, and that's it. But most scientists, in 0:12:18.440 --> 0:12:21.760 my experience, they are you know, scientific realists. They think 0:12:21.800 --> 0:12:24.439 that the things that we're probing are really out there. 0:12:24.440 --> 0:12:26.480 I mean, the reason that I'm a particle physicist and 0:12:26.520 --> 0:12:29.760 not a mathematician is that I want to know what's 0:12:29.760 --> 0:12:32.360 really out there. I think of myself was revealing the truth. 0:12:32.400 --> 0:12:35.400 And when I'm at cern if I ask people, hey, 0:12:35.400 --> 0:12:37.839 do you think the Higgs boson that we discovered is real? 0:12:38.080 --> 0:12:40.319 Or is it just something in our models that let's 0:12:40.480 --> 0:12:43.120 accurately predict experiments, most of them would look at me 0:12:43.160 --> 0:12:45.400 like I'm crazy, you know, like I had something bad 0:12:45.440 --> 0:12:48.800 for lunch. It feels to me like they're doing philosophy 0:12:48.960 --> 0:12:52.080 by rejecting the question, even though they don't imagine they're 0:12:52.120 --> 0:12:54.200 doing philosophy. Why do you think that's sort of the 0:12:54.320 --> 0:12:58.440 natural position of most physicists to imagine, you know, a 0:12:58.480 --> 0:13:02.120 strong philosophical argument and um that everything we're out there 0:13:02.240 --> 0:13:04.720 is actually real. Why do you think that most physicists 0:13:04.760 --> 0:13:08.600 don't consider the whole spectrum of philosophical positions there? I 0:13:08.640 --> 0:13:13.559 think because it's a sort of natural or default human inclination. 0:13:13.800 --> 0:13:16.440 First of all, to be a metaphysical realist in the 0:13:16.800 --> 0:13:19.080 in the minimal sense of there is a way the 0:13:19.080 --> 0:13:23.760 world is subjectively speaking, and then to go beyond that, 0:13:23.880 --> 0:13:30.000 to think if we have powerfully predictively accurate ways of 0:13:30.360 --> 0:13:36.440 describing the patterns of our experiences. Then those must correspond 0:13:36.559 --> 0:13:39.880 to something objective. If I'm being very vague here, but 0:13:40.400 --> 0:13:44.400 something in reality is accounting for the fact that our 0:13:44.480 --> 0:13:49.160 inductions are successful. It may not be a perfect isomorphic 0:13:49.320 --> 0:13:53.000 overlap right between what we say, either in common sense 0:13:53.679 --> 0:13:57.720 predictions or categorizations, or even in high level theory, but 0:13:58.040 --> 0:14:03.240 there's some degree of congruents um there. We're tracking. I 0:14:03.280 --> 0:14:05.040 guess with what I'm trying to say, we must be 0:14:05.120 --> 0:14:09.520 tracking something real. And then when you think about fundamental physics, 0:14:09.559 --> 0:14:14.359 because it's going so deep into the foundations, the inclination, 0:14:14.480 --> 0:14:17.880 I guess it becomes natural to think we're getting closer 0:14:17.920 --> 0:14:21.960 and closer to it isomorphism. The categories we're using are 0:14:22.080 --> 0:14:27.000 are are tracking very directly these entities. But it feels 0:14:27.080 --> 0:14:31.440 something more squishy than we usually find in physics. You know, physics, 0:14:31.480 --> 0:14:34.480 we have math and calculations and these sorts of things. 0:14:34.680 --> 0:14:37.880 Here we're talking about like a feeling that what we're 0:14:37.880 --> 0:14:40.960 seeing out there is real, and you know, our ideas 0:14:40.960 --> 0:14:43.200 about the universe must be real. It feels a little 0:14:43.200 --> 0:14:47.920 bit more susceptible to you know, cultural bias or parochialism, 0:14:48.160 --> 0:14:50.600 or thinking the way people have always thought. To me, 0:14:50.720 --> 0:14:52.680 one way to make sense of this question, to make 0:14:52.680 --> 0:14:55.320 it a bit more concrete, is imagine a scenario like 0:14:55.480 --> 0:14:59.360 we meet alien physicists and we talk to them about 0:14:59.360 --> 0:15:02.120 the universe. If what we're learning about the universe is 0:15:02.200 --> 0:15:04.440 real in a sense that it's not just biased by 0:15:04.440 --> 0:15:07.200 our human conception, then we can imagine maybe they have 0:15:07.280 --> 0:15:09.880 discovered the same things. They also found the Higgs boson, 0:15:10.000 --> 0:15:12.400 and they have group theory as a foundation of their 0:15:12.480 --> 0:15:15.240 description of the fundamental particles. But if it's not, if 0:15:15.320 --> 0:15:19.160 instead we have some human element to this understanding, or 0:15:19.160 --> 0:15:21.960 that what's out there has no relationship, you know, to 0:15:22.040 --> 0:15:24.320 the model that we've built other than that it works, 0:15:24.920 --> 0:15:28.560 then maybe aliens would have completely separate ideas about physics. 0:15:29.120 --> 0:15:31.600 You think that's a reasonable way to frame this question 0:15:31.640 --> 0:15:33.800 of whether what we're probing is real, whether it could 0:15:33.880 --> 0:15:36.720 also exist in the minds of other intelligent creatures. Sure, 0:15:37.520 --> 0:15:40.760 I mean imagine first of all that at some stage 0:15:40.760 --> 0:15:44.480 in physics, um clever theorist story able to come up 0:15:44.560 --> 0:15:50.440 with two very different ways of categorizing phenomena, but they 0:15:50.480 --> 0:15:54.560 were equally predictively successful. Then I think the natural conclusion 0:15:54.600 --> 0:15:57.560 we would all draw, as it's underdetermined, at most one 0:15:57.600 --> 0:16:00.920 of these, if they're incompatible frameworks. Uh, at most one 0:16:00.960 --> 0:16:05.600 of these is true. Perhaps neither. Um we need more information. 0:16:05.880 --> 0:16:08.920 But one of the great, of course achievements of physics 0:16:08.960 --> 0:16:13.960 has been to increasingly try to break away from a 0:16:14.360 --> 0:16:18.280 narrowly provincially human way of looking at things. That's very 0:16:18.320 --> 0:16:20.120 difficult to do. And at some point I expect we'll 0:16:20.120 --> 0:16:22.960 come back to this. I think there are limits to 0:16:23.560 --> 0:16:27.560 how far one can go with that rationally, because at 0:16:27.600 --> 0:16:31.200 the foundation of the evidence for scientific theories, right the 0:16:31.240 --> 0:16:35.640 epistemology of science, are scientists in the activity of science. 0:16:35.760 --> 0:16:40.240 And we can't end up endorsing frameworks in which we 0:16:40.320 --> 0:16:45.160 cannot locate the rational inquirer in the community of inquirers 0:16:45.160 --> 0:16:48.840 and there and the activity of inquiring. And I have questions. 0:16:48.920 --> 0:16:51.600 It's very challenging. But you know, some of the more 0:16:51.640 --> 0:16:56.800 speculative attempts to unify fundamental particle physics and you know, 0:16:56.920 --> 0:17:01.400 large scale cosmology, I worry that they they're udding up against, um, 0:17:01.600 --> 0:17:06.240 these kinds of limits that they're they're positing models that 0:17:06.320 --> 0:17:11.480 we could imagine for some entirely disconnected reality. Right, they're 0:17:11.520 --> 0:17:15.240 perfectly coherent models for describing something, But could they describe 0:17:15.240 --> 0:17:18.960 our reality? Could we have reason to believe? Right? You know, 0:17:19.040 --> 0:17:21.680 there there, we are right in that question. Could we 0:17:21.800 --> 0:17:25.520 have reason to believe that we inhabit a world correctly 0:17:25.960 --> 0:17:28.800 depicted by this model? There's a tricky question there at 0:17:28.840 --> 0:17:31.920 the limit. It's certainly interesting to wonder about whether humans 0:17:31.960 --> 0:17:35.240 can imagine what humans can't imagine, right? Can we think 0:17:35.240 --> 0:17:38.160 our way out of our own box? It's it's certainly unknown. 0:17:38.200 --> 0:17:40.840 I'm really curious about the point you made earlier about 0:17:40.920 --> 0:17:44.919 whether there could be alternative and completely functional descriptions of 0:17:44.960 --> 0:17:48.359 the universe that are conceptually different. Like if I describe 0:17:48.560 --> 0:17:50.760 the universe with my theory of everything and it has 0:17:50.880 --> 0:17:53.080 squiggles in it, and I say, look, my theory works, 0:17:53.119 --> 0:17:55.560 squiggles must be real, and you know, you have your 0:17:55.600 --> 0:17:57.960 theory and it has squaggles in it, and you're like, no, 0:17:58.040 --> 0:18:01.000 squaggles are totally different from squiggles, and my predictions are 0:18:01.080 --> 0:18:02.960 just as good as yours. Then you're saying, we're faced 0:18:03.000 --> 0:18:06.199 with a question, are squaggles real? Are squiggles real? Is 0:18:06.240 --> 0:18:09.639 anything actually real? Is that the basic idea. And doesn't 0:18:09.720 --> 0:18:14.000 that sound very similar to the current situation about the 0:18:14.080 --> 0:18:17.359 nature of fundamental particles and the questions about quantum mechanics. Right, 0:18:17.400 --> 0:18:20.280 we have very very different conceptions of like what is 0:18:20.359 --> 0:18:24.440 real at the smallest scale, relational quantum mechanics, boney and mechanics, 0:18:24.520 --> 0:18:27.880 all apart from the you know, sort of orthodoxical Copenhagen interpretation, 0:18:28.119 --> 0:18:30.360 aren't we sort of in that situation. None of those 0:18:30.400 --> 0:18:34.040 theories give any real variation in their predictions, but they 0:18:34.080 --> 0:18:37.879 have completely different stories about what's happening in the microscopic scale. 0:18:38.000 --> 0:18:40.560 Does that mean that nothing is real or just that 0:18:40.600 --> 0:18:43.760 we haven't found which one is real? I think the latter, 0:18:43.840 --> 0:18:46.159 that we haven't found which one is real. And of 0:18:46.200 --> 0:18:49.320 course you're the expert here, not me, But I like 0:18:49.400 --> 0:18:52.480 to chat with the philosophers of physics and the occasional 0:18:52.560 --> 0:18:58.600 particle there theoretical physicist about the conceptual challenges in in 0:18:58.760 --> 0:19:04.320 quantum mechanics and in unifying quantum mechanics with space time theories, 0:19:04.560 --> 0:19:07.480 and so as I'm told. For example, so you've got 0:19:07.520 --> 0:19:11.320 this Bowman interpretation, one interesting feature of which is it's 0:19:11.359 --> 0:19:16.200 a deterministic theory about the dynamics of the universe, unlike 0:19:16.320 --> 0:19:18.960 at least a couple of the other leading theories. Whether 0:19:19.040 --> 0:19:22.400 or not we call many universe theory a deterministic theory 0:19:22.480 --> 0:19:25.600 is a somewhat subtle question, I think. But I'm told 0:19:25.920 --> 0:19:30.119 that while these four frameworks all have the same predictive 0:19:30.240 --> 0:19:33.920 consequences for the kinds of experiments we can do now 0:19:34.119 --> 0:19:38.240 or have done, that, there are in principle Bowman mechanics 0:19:38.280 --> 0:19:43.040 could have um different predictions, and so we could potentially, 0:19:43.640 --> 0:19:45.680 I don't know how far off this might be, but 0:19:45.760 --> 0:19:50.080 we could potentially have evidence that bore differentially between bow 0:19:50.080 --> 0:19:53.320 Mean mechanics and at least some of the alternatives. So 0:19:53.400 --> 0:19:56.199 that suggests, yeah, we don't know. So then we're just 0:19:56.480 --> 0:19:59.320 right currently, you know. But we're still interested in the question. 0:19:59.400 --> 0:20:01.680 It may not upen in our lifetime. So the question 0:20:01.760 --> 0:20:05.760 is should we be completely agnostic? And here the different 0:20:05.800 --> 0:20:10.480 theories have different kinds of theoretical virtues and vices. Insofars, 0:20:10.560 --> 0:20:16.159 one is willing to say purely general characteristics of theories 0:20:16.359 --> 0:20:21.520 in terms of simplicity of ontology and things like that, 0:20:21.880 --> 0:20:25.400 or whether it makes you requires you to make certain 0:20:25.560 --> 0:20:30.200 very outlandish seeming hypotheses, whether you give that any kind 0:20:30.240 --> 0:20:34.199 of evidential weight at all might determine whether or not 0:20:34.240 --> 0:20:37.360 you think we have reason to lean in one direction 0:20:37.440 --> 0:20:40.200 or the other, even if we don't have conclusive evidence. Well, 0:20:40.240 --> 0:20:42.800 I hope that experimentalists are clever enough to come up 0:20:42.840 --> 0:20:45.480 with ways to test these various hypotheses and tell us 0:20:45.640 --> 0:20:48.680 what's actually happening at the smallest scale one day. So 0:20:48.720 --> 0:20:51.320 I have a lot more questions for you, especially about emergence. 0:20:51.440 --> 0:21:06.560 But first let's take a quick break. All right, we're 0:21:06.560 --> 0:21:09.879 back and we're talking to Professor Tim O'Connor, philosopher of 0:21:09.920 --> 0:21:14.119 science and follow upon, Grand Champion of the World, who's 0:21:14.160 --> 0:21:17.520 answering my naive questions about philosophy of science and whether 0:21:17.560 --> 0:21:20.960 we can understand what's out there and whether it's real. 0:21:21.280 --> 0:21:23.119 I first came to read your work because I was 0:21:23.240 --> 0:21:26.919 very interested in the question of emergence cases where we 0:21:26.960 --> 0:21:30.000 can describe things we see in the world using rules 0:21:30.000 --> 0:21:32.960 that are very different from the rules of the underlying bits. 0:21:32.960 --> 0:21:34.399 It's like if you have a set of rules for 0:21:34.440 --> 0:21:36.720 how legos work, but once you put the legos together 0:21:36.720 --> 0:21:39.879 into complicated objects, you're better off describing their behavior in 0:21:39.960 --> 0:21:42.040 a new set of rules, like in a game of 0:21:42.080 --> 0:21:45.199 life where simple objects with simple rules come together and 0:21:45.359 --> 0:21:49.360 very complex behavior emerges. How would you define this concept 0:21:49.440 --> 0:21:52.640 of emergence and why in your views? Emergence and important 0:21:52.680 --> 0:21:56.719 question in philosophy of science. Yeah, so it's always been 0:21:56.720 --> 0:22:00.000 a controversial idea, and it emerged in the nineteenth century 0:22:00.000 --> 0:22:04.240 people began thinking, uh, in emergence terms of it's it's 0:22:04.280 --> 0:22:07.879 a question about the relationship of science at different levels 0:22:07.920 --> 0:22:11.959 of grain. So, how does physics relate to chemistry, chemistry 0:22:12.000 --> 0:22:16.520 to molecular biology, biology to organismic biology, and and so, 0:22:16.640 --> 0:22:20.720 and then our biology to human psychology neuroscience and the 0:22:20.760 --> 0:22:25.160 brain to human psychology. And the emergent test is a 0:22:25.200 --> 0:22:30.280 person who, in very general terms thinks that organization of 0:22:30.359 --> 0:22:36.680 certain kinds gives rise to new features, new new patterns 0:22:36.720 --> 0:22:40.679 that have a certain degree of autonomy with respect to 0:22:40.720 --> 0:22:44.359 the lower level underlying dynamics. It's a new form of 0:22:44.480 --> 0:22:48.200 dynamics of patterns that the kinds of concepts you need 0:22:48.240 --> 0:22:50.720 to describe what's going on are different than the kind 0:22:50.720 --> 0:22:53.360 of concepts you need to do the lower level science. 0:22:53.680 --> 0:22:57.959 And uh. Left at that um that there is emergencies 0:22:58.320 --> 0:23:01.800 entirely uncontroversial. There is such a thing as chemistry, and 0:23:01.880 --> 0:23:05.879 chemistry can be understood to a degree, at least at 0:23:05.920 --> 0:23:09.639 an elementary level apart from quantum mechanics, and certainly biology 0:23:09.680 --> 0:23:14.160 can be understood without knowing anything about quantum physics and psychology, 0:23:14.200 --> 0:23:18.520 you know, you one can even do psychology of various kinds, 0:23:18.640 --> 0:23:22.119 of social psychology, of normal psychology, and so on without 0:23:22.200 --> 0:23:25.520 knowing anything about physics or chemistry. So there are patterns 0:23:25.720 --> 0:23:28.360 in the world that have to do with organized systems 0:23:28.359 --> 0:23:31.080 of a certain kind, robust patterns, patterns where you can 0:23:31.119 --> 0:23:33.920 predict phenomena. I mean, think about the fact that if 0:23:33.960 --> 0:23:37.160 I were to go agree to fly out to California 0:23:37.280 --> 0:23:40.159 to meet up with you, and three days later I 0:23:40.480 --> 0:23:44.600 show up at your office door, and you quite confidently 0:23:44.720 --> 0:23:48.080 believe that that's going to happen, And that involves the 0:23:48.160 --> 0:23:52.040 movement of a hunk of matter that's coalesced in a 0:23:52.240 --> 0:23:57.280 fairly organized way, transporting itself across a great deal of distance. 0:23:57.320 --> 0:24:01.680 And could you predict that in terms of physics, Well, 0:24:01.760 --> 0:24:06.160 certainly not, given your and given our computational limits. Right, 0:24:06.240 --> 0:24:08.840 But you know, psychology works beautifully well, right, I mean, 0:24:08.960 --> 0:24:12.080 we can predict human behavior to a certain degree just 0:24:12.480 --> 0:24:18.520 by attributing to people beliefs, desires, intentions, uh, and so on, 0:24:18.840 --> 0:24:21.880 and you can be completely ignorant. People were doing this 0:24:22.240 --> 0:24:26.080 a thousand years ago, knowing nothing about the physical, underlying 0:24:26.080 --> 0:24:29.080 physical structure of the world. So there's a sense in 0:24:29.119 --> 0:24:33.920 which it's it's obviously true that there are emergent phenomena. 0:24:34.160 --> 0:24:38.560 So weak emergence is the uncontroversial kind. Weak emergence says 0:24:38.680 --> 0:24:43.480 there are organized phenomena that have their own characteristic forms 0:24:43.520 --> 0:24:47.440 of activity, their own characteristic features, and the kind of 0:24:47.520 --> 0:24:51.160 dynamics for how how this activity unfolds. But the weak 0:24:51.200 --> 0:24:56.280