StarTalk Radio - The Philosophy of Physics with Elise Crull

Episode Date: June 24, 2025

What happens when physics meets the big questions of philosophy? Neil deGrasse Tyson and comic co-host Chuck Nice sit down with Elise Crull, philosopher of physics at CUNY and author of The Einstein Paradox, to explore physics, philosophy, and how thought experiments shape real science. NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free here: https://startalkmedia.com/show/the-philosophy-of-physics-with-elise-crull/Thanks to our Patrons Jason Dobbins, Robert Egoroff, Steven Rodby, David Miller, BiologyBob, Charles William McDonald, kara lockmiller, Cade Solsbery, Cakery, Eugene Swimmer, Andrew Di Bello, Bob Patterson, Melissa Buchter, Mathew, Mike Dockins, A Wade, Harrison Netherway, Padraic Hagerty, Bryan Nusbaum, Jorge Daniel, Samir Banerjeesh, Chad Salter, Helix, Mohammad Imrul Kayes, Bryson Taylor, Mickey Kellam, Susan Pingree, ThatStratosPlayer!?, Sam Tuttle, Henock Taddese, Rosemarie Boll, Alex Pilon, Trevor Carpenter, Max Laarmann, Melissa Hannah, Donna Van Benschoten, David Quilloy, John Kordyback, Tony S, Francisco Rubiolo, Mallory Boyd, Briana Green, Laurie Smith, Grey Gorman, Mark Bentley, Joseph Formisano, Velovinovicci, tosha ristoff, Isaac Woosley, Lucas Legey, and Carl Dalby for supporting us this week. Subscribe to SiriusXM Podcasts+ to listen to new episodes of StarTalk Radio ad-free and a whole week early.Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus.

Chuck, why is it every time we have a show that goes to the frontier of science, you need an edible? Because that is how I cope with science. What do you cope with science? Some people don't need to cope with science. I need to cope with science, and so. The frontier of philosophy, quantum physics, and physics, coming right up.

Welcome to StarTalk, your place in the universe where science and pop culture collide. Star Talk begins right now. This is Star Talk, Neil deGrasse Tyson, your personal astrophysicist. I got Chuck Nice with me, Chuckie baby. Hey, what's happening in the eye? Love it when I look over and I see you there. Oh, you know the feelings me a tool

It's almost like I'm looking at myself So we're doing something we haven't yet done okay show. All right, we're gonna do the philosophy of physics What I know that's why we haven't done it And we had somebody right up the street. In the hood. Actually, literally in the hood. Up in Harlem. And this is Elise, can I pronounce your last name?

Kroll. Elise Kroll. Elise Kroll, welcome to Stark Talk. Hey, thanks for having me. Yeah, so you're a professor of philosophy in the philosophy department. That's right. This is a CUNY.

Yep. And you authored a book just last year came out, but it was like a very serious academic tome, The Einstein Paradox. This is a very seductive title, okay? Einstein, paradox, the debate on non-locality and incompleteness, oh, come on, in 1935. So the title actually comes from Schrodinger.

He had a folder in his archives. Schrodinger. Schrodinger. Of cat fame. Of cat fame. And in fact, the cat was born in this correspondence with Einstein that he had labeled in German, the Einstein paradox.

And so we translated those letters into English, many of them for the first time, and it's all the famous physicists Talking to one another about what this physics so why can't regular people read this they sure can It's just that the primary literature in particular I just reading the way that Einstein and Schrodinger and Heisenberg and Borg talked to one they had their own language Oh, yeah, okay did and they had their like twins their own language. Yeah, okay.

They did. And they have their own. Like twins. They just have their own thing. You like twins that get their own language? Except in this case, their own language was often German. Okay. Some cases Danish.

Danish would be for Borg. That's right, that's right. But they all had a really nuanced, like they had different ideas about what was problematic about quantum mechanics. Interesting. Quantum mechanics is just being born at that time. nuanced stance, like they had different ideas about what was problematic about quantum mechanics. Interesting. Because quantum mechanics is just being born

at that time. It's about 10 years in at this point. Yeah, and what precipitated this was Einstein, well, Einstein had had conversations with two guys, Podolsky and Rosen, about what he felt was an issue that quantum mechanics was correct, but it wasn't finished yet, it wasn't complete. And guess what? He was right yet, it wasn't complete. And guess what?

He was right. It still isn't complete. So that book is by Cambridge University Press, which has quite the catalog of astronomy and physics books for the public. Yeah, and I mean the book is intended for people who are interested in learning from the physicists at that time themselves, their philosophical

and physics sort of worldviews, and learning about this history. I don't understand the use of philosophical when it comes to their physics. Let's start right there. Let's just, you are a professor of philosophy specializing in the philosophy of physics. So what is the philosophy of physics in modern times?

So I know what it was in the day. Because in the day. What's the day? Antiquity or the Renaissance? No, post-Galileo. Newtonian worldview. Yeah. Okay, got it.

Yeah, back then. Scientific revolution. Yes, back then philosophers were physicists. I mean, they were one and the same. That's right. And in fact, Newton's greatest work has the word, the word physics isn't even in the title. That's right, the Principia doesn't even have equations

in the first part. Oh, okay. The title is, well, in Latin, but it's The Mathematical Principles of Natural Philosophy. Okay. That's right, natural philosophy fits the same thing? Yeah, yeah, natural philosophy was physics. It's the deep thinking about how nature works.

Okay, so we got that, but into the 20th century, you get quantum physics, where you can't deduce from an armchair, and you have the expanding universe who thought that up, right? And so all this. And the confirmation of all these things that were mathematically postulated and then proven to be the actual case.

So what I've noticed was that there was a sort of a separation of the turf. And the philosopher couldn't really contribute to physics unless they were actually a physicist. You could still think philosophically, but you needed to be in the lab. You couldn't just sit back and observe and think deep thoughts.

Not what the university would do. Well, Einstein was never in a lab. Right, but he was a physicist, not a philosopher. I don't think he would make that distinction. Let me say it differently. Okay. He was trained as a physicist, not trained as a philosopher. Oh.

And that's the distinction I'm making. So here's a philosopher. And that's the distinction I'm making. That is the distinction I'm making. If Mel Brooks were doing a sketch with him, would he say to Einstein, in the philosopher unemployment line, did you bullshit today? Did you try to bullshit today? Are you planning on bullshitting in the future?

Is that from History of the World? History of the World. That from History of the World? History of the World. That's History of the World. That's actual quoting. So I'm distinguishing between people who go to school to be a philosopher and then attempt to contribute to the physical sciences, whereas you could do that in the day, and I don't see that happening today,

unless you're busting that wide open in your existence in the world and in this office right now. Yeah, yeah, yeah, okay, a couple of comments. All right. First of all, in the German university system in which Einstein and Schrodinger and Bohr and all these guys were trained, they learned a hell of a lot of philosophy.

Sure. And even Einstein into his post. I'm gonna say, people didn't have philosophy chops. I'm saying, if you go to school to be a philosopher, in the 20th century, you became less and less useful to the moving frontier of the physical science. That's the only point I'm making. Now go.

Unless you're gonna bust that open. Well, the first thing is, I don't accept your premise that in order to do what I do. That's how you start an argument. That's how you start an argument. I think we're welling our way into a philosophical debate. Your premise is invalid. Okay, go.

Well, a premise can't be invalid, only a whole argument can be valid. But I'm being an asshole on purpose because it's funny. The idea that what I need to do is be useful to science, to be important or worth doing as a human endeavor is a pretty narrow view. Except that's how it used to be important or worth doing as a human endeavor is a pretty narrow view. Except that's how it used to be. How what used to be.

Philosophers were useful to the moving frontier. You have Kant thinking up stuff, that the nebular hypothesis was kind of cool. And you had. So Einstein's own ability to get the theory of special relativity had to do with his taking a different approach than Lawrence and Poincaré and others who were looking for a similar theory. Yes, exactly.

He said, let's step back. That is a choice to step back and say, we have these data, let's understand them a different way. I agree. Now, if you're saying it's about how we specialize into different disciplines, yes. Yes. That is something that naturally occurred as our measuring apparatuses and our technology got better. We were able to, and you go to a conference

in astrophysics nowadays, how many talks do you even are interested in, like hyper specialized? Fair enough. Yeah, I published a paper, 100 people in the world will understand it, or no, 100 people in the world will care about it. Right, for me it's like maybe six. Oh, it's worse. They're my buddies, you know?

Okay, yeah. It's like when people are like, oh, how do I find you on the internet? Like, Google Elise in philosophy of physics, because I think I'm the only one. So let me just, let me back up as a lay person and kind of broaden the view here. The intertwining that Neil was talking about

that existed at one point, that you now say has kind of dissolved because of highly specialized training, where does that intersection happen now? Good, yeah. Good question. That's great. And I think that's exactly the question we want to, so you're asking,

am I going to blow it open now? Yeah. I think the fringe, like the edge of science right now is in this place, so you're talking about people who are looking for a theory of this place. In this place. In this place, metaphorically and mentally. In the office at the Hayden-Bloom Tower.

Right now. It happens here and now. Localized entirely in this room. We're in the roomically and morally. Marshall is at the Hayden Black Tower. Right now. It happens here and now. Localized entirely in this room. We're in the room where it happened. Ha ha ha. Ha ha ha. Ha ha ha. Okay.

Okay. We're getting beyond our means to empirically test, and you know as a cosmologist and astrophysicist, there's a limited amount of data that we. On that frontier, yes. On that frontier, and that's true also in looking for theories of quantum gravity. Yeah, all of that.

I mean, we haven't yet found conclusive evidence for the Lambda CDM model that is only for the Lambda CDM model of cosmology. It's the best we have right now. It's the cold dark matter and dark energy. It's just... The concordance model, like the model we think is the best model of the universe right now.

I can just catch people up. So we know the universe is accelerating in its expansion and what's causing that we call dark energy. We just call it that. We don't know. But it's a black box quite literally. And then dark matter is a mysterious source of gravity in the universe.

In fact, it's 85% of the universe is gravity. And we don't know what that is either, but if we assume it's a thing, because we measure it, and then we can calculate with it, and with some assumptions about the behavior of matter, we get a sort of a, kind of our own standard model of how the universe works. It's called Land of the CDM, Land of the Cold Dark Matter.

And we work with it, it gets us some understanding. It does some good work for you. Yeah, it's a workhorse. But it's not a complete picture. It's a complete theory, okay. So this is true in a lot of arenas of physics, and so what philosophers of physics can do, although I think there are many ways

to be a philosopher of science, is not just like you're trained in philosophy, but you sort of ask philosophical questions of science itself. How many philosophers of physics are there? I don't know. More than five, but less than 200? Okay.

Wow. No, maybe there's more than 200. It's hard to say. You're the first one I've ever met. Oh, really? Yeah, I've met philosophers, but just think about everything. Right.

It's a small field to be fair, and I will also say back to your early point, most of us have training in physics as well, because that's important to us. Like what I do. You're an undergraduate. My undergrad is in physics, but then I also continued,

I mean I wrote my doctoral thesis on quantum decoherence, so like I was learning about the models that people are using. So you're gonna say you're quantum thoughts. Yeah, physics chops. Yeah. But you. Yeah, so was that in the physics department or the philosophy department? So I was in the philosophy department, but I was part of a history and philosophy of science

program, but I also took a number of physics courses. From the physics department. Okay, so you're just blending all of that. All the things. You just put it all together. However, that's a great way. To bust a move. That's a great way to make sure that you get an A.

Why? Why? Because. Yeah, how does that correspond to getting a good grade at all? Here's how it works for getting a good grade. Oh good, I'm listening. So you have, your philosophy people,

they don't know crap about physics. And your physics people, they don't know crap about philosophy. So you're just like, yeah, you're going to have to take my word for it. That's exactly right. We're all just pretending. No, go ahead.

So this ties into your early question. It's like something about the extreme specialization has meant that in particular, the way we train physicists in the US, even in high school, is so divorced from the deep questions about, but why, but how? It's about following a scientific method.

Did you study abroad? No, but I've studied, I've looked at education policies in other countries and sort of, it's no surprise that our stuff, that we're not, you know, we're still the best place to go for STEM at the graduate level, but we're losing that. And there's a history about that, in particular, there were decisions made in the Cold War era

to train people in science in a particular way that was gonna get technologies built, that was gonna be good for industry, and for the Department of Defense. That's right. And it became, not just not in vogue, but like it became. In fact, I have the original document in this office. Of the NSF creation of. Yes, I have that document.

Can I reach for it? Yeah, show it to us. Let's have a visual here. This is what you're talking about. Yeah, Vannevar Bush. Let's let out people at home. Making a case for why America needs to preserve and fund science.

And I think that was an easy case to make because it was physics that won the war. Well, that definitely helps an argument. I'm just saying. But there's a reason. No, this is good, this is good, this is funny. That's funny. Science the endless frontier.

Science the endless frontier. Yes! A report to the president. This is 1945. Oh wow. This established. So this went to the president, this right here. This, he, Vannevar Bush, was basically the first

science advisor to a president. Right. Okay, right. Okay, and he's advising. I don't need one of those. Nobody knows more about science than I do. That's really good. I know, he's got it. I'm getting angry over here, just wait.

That's how you know it. So here's what I want you to do. Just read the chapter, the section headings there. Just read them, read them. Introduction. Introduction. Okay. Yeah. Well played.

Okay. Excellent. The war against disease. These headings you mean are like science and public welfare, renewal of our scientific talent, a problem of scientific reconversion, the means to an end responsibilities for the government.

Yeah, the means to an end, okay. So everything I know and think of about how science happens in the United States, when I pull up this original document, it's all there, and so I have, is it a bias? I say, that's how you do science. But are you suggesting there's another way to do science? I'm suggesting that when you get to the level

of how we educate, when you divorce, you understand science is a thing that's about usefulness and application that is one very small color from a spectrum of colors. And I'm also suggesting that when we look at people who are trained in the history and philosophy of science along with the science itself in high school, they're testing off the charts.

There's something about being able to ask that why? Why are we using this equation to solve for the energy level of a hydrogen atom? Why are we understanding? That never showed up in any of my classes. That's right. That's right. That's absent. You were taught, it's amazing to me that-

I was taught physics as a thing, not as a way of thinking. I had to like realize that it was a way of thinking and bring to it the bit of philosophical meanderings that I had engaged in my life. I had to bring that to the physics. That was not there when it was taught. And you're told not to have it there, right?

Well, not explicitly. It's not encouraged and it's not rewarded. with my son Ernie because we listen to Star Talk every night and support Star Talk on Patreon. This is Star Talk with Neil deGrasse Tyson. Okay, let me ask this. So what is it about asking these big questions? The why questions. The big big questions. The why questions. The big why questions.

What is it about that that contributes to the guiding principles of science itself? Because there's no one recipe for how to do good science. Okay. Okay, it is true. When I go to my different, everybody's got their own angle on science, it's true. There was no centralized approach.

Right, well, but even if there were. So you're telling me that this centralized our approach, not to our greater good. I think it did in some ways to our greater good because I mean, Vannevar Bush wanted the inner core of funding for NSF to be pure science. He thought there was always supposed to be a part of it that wasn't.

Whatever funding's left of it. As of. Let us hang our heads in a moment of silence. The real question is, do I get a plane from the NSF? But did you know that if you drop a magnet into a glass of water, it loses its magnetism? Yeah, he said that. He said that. I love that. He said that.

I love it. He said that. Yeah. And by the way, I'm still right. But it has to be Avion water. It just does. It's like. It's like.

It's like. It's like. It's like. It's like. It's like. It's like. It's like. It's like.

It's like. Sorry, I'm sorry. Go ahead. Why you keep disrupting the lady? I know. I'm so sorry I'm sorry. Go ahead. Why are you keep disrupting the lady? I'm so sorry. Get back. This is like real world out there. It's like we're trying to do scholarship and then things. But also, let me ask you this, Neil. Would you have been interested in doing science if it was taught to you as like following a recipe? Like the scientific method?

Like, boo, right? My philosophical interest in the universe was self-driven. I was taught that. it was taught to you as like, following a recipe. Like the scientific method, like, ooh, right? My philosophical interest in the universe was self-driven. It did not come from any book that I was taught. Right. And my writings today, I don't want to say they're dripping with philosophy, but they take an angle on the content

where it's not just, here, learn this. It's, think about it in this other way. That's very cool. So, I mean, here's a metaphor, if you like. I mean, a lot of people can follow recipes and make really good dishes, really tasty dishes. So there's something wonderful about that. But the truly inventive chefs are the ones who say,

well, or even the better cooks, I'm a terrible cook, but like are the ones who say, but why do I melt the butter to this temperature? Why do I add the salt at this stage? Or why is this, these flavors work together? Expertise is something that our country is not, has a very interesting, tortured relationship. Yeah, that's right.

So let me ask you this. Often philosophy is thought of as a belief system, okay? But in science. Let's sow in the sciences. Right, that's what I'm saying. Often philosophy is thought of as a belief system, okay? But in science. Let's sow in the sciences. Right, that's what I'm saying. But in science, you definitely don't want to be biased by your beliefs. So the one thing you want to do is divorce yourself

so that whatever results you get, you're able to accept, irrespective of how you feel about them or what you believe, how is that reconciled? Good. And let me add something to that. Yeah, ooh, it's a lot of good questions. Let's go back to Kepler, who was, dare I say, philosophically driven to think that the orbits

of the planets could be nested in such a way that they resembled the platonic solids. The platonic solids. Nested spheres, which always makes me think of Tupperware for some reason. But yeah. So what he knew was that geometrically in mathematics, there are only five, what are called platonic solids.

These are solid shapes where every surface is the same two-dimensional shape. So a cube is such a thing. Every side is identical and has six sides. A pyramid is the same, okay? A four-side, so you have four triangles and they can all be equilateral triangles. So there are five of these shapes.

He saw that there were six planets and he thought to himself, maybe there's a divine connection between the two because the planets, it's the universe, it's where God lives, right? And then we're just mere mortals here. God surely knows what he's doing and math is perfect, right? And then we're just mere mortals here. God surely knows what he's doing, and math is perfect, right?

Math is badass. So he nested these in different ways to try to find out whether the separations of the planetary orbits could match what these solids would be if they were nested Tupperware style, okay? He was also thinking in terms of harmonic resonances, but yeah.

Right, and so my question to you is, he, I don't wanna say he wasted 10 years. He devoted 10 years to this point of view, and it took him that long to abandon it in favor of something that was not so philosophically beautiful. So in that case, getting back to Chuck's point, the philosophy prevented him from seeing the answer

because he was driven by this concept of divine perfection. So there's a couple of different ways we're talking about philosophy, right? There's the philosophy of just, I mean, if you go to a philosophy section at Barnes and Noble's or whatever, what they have there in the metaphysics section is some weird, new agey stuff.

It has nothing to do with what academic philosophers are doing. And academic philosophers are asking questions about what is the nature of personhood, what is knowledge, do different people reason in different ways, what are ethical questions, what is the philosophy of law, philosophy of science, these sorts of things. They're, we have a specific, we have specific tools that we bring to bear on that. When scientists think about it, I think they're understanding not philosophy as a discipline,

but they're thinking about like a worldview. And we come to everything with a worldview, with a lens. That's inescapable. Now you're right that part of what scientists want to do is sort of shield, maybe not shield for that or at least normal, neutralize it in some way. We want to think about whether our comments are value-laden and I don't just mean value

in an ethics way but maybe also do I privilege certain epistemic values like beauty or similarity and many do. Many do but I can tell you this, to the extent that I can understand myself, I leave all philosophical preconceptions at the door. You can't do that though. I said to the extent that I'm able.

I'm self-aware that I could be constrained by a philosophical thought. So I remain open to anything I see and anything I measure and what that could possibly mean and without discounting it. And the reason why I'm going there is I had an issue in Hamlet. Okay. One of the lines is,

there's more betwixt heaven and earth than a dreamt of in your philosophy. Right. And I never understood that comment, ever. Because as a scientist, if a ghost shows up, fine. Let me make some measurements. I have no issue with that. So why does that sentence make any sense at all

until I realized that people who are deeply into a philosophy of belief do close off their access to things that fall outside of their understanding. Or their awareness. And so a good scientist has no philosophy, otherwise they're gonna miss stuff. Bad scientists will have a philosophy

and they'll miss everything. Your choice to set aside some world so that you can be neutral. Is itself a philosophical position? That's a very good point. That is ineliminable. In what? Ineliminable.

That's a word. That you are going to walk in with some interpretive framework. Ineliminable. Ineliminable. Cannot be eliminated. Cannot be eliminated. Cannot be eliminated.

Ineliminable. Ineliminable. I've got some big words here. I would say that the philosophy that I have no philosophy is a very mild version of a philosophy. The point is that you cannot wait. Yeah, I was gonna say, she's about to tell you. I'm listening. No, she's about to say,

that's like being a little bit pregnant. Let me hear what she's saying. Okay? You can't be a little bit pregnant. Let me hear what she's saying. You can't be a little bit pregnant. Can we hear the lady? Okay, go. Yeah, well, so when you walk into the lab or whatever, it's not like you take off your religious hat

or you take off your cultural, you're an integrated whole person. And how you were trained and what you were thinking about that morning and what you're predisposed to look for in the equations themselves, those things play a role. Now there's a huge conversation in the philosophy of science about whether certain things are more or less appropriate

when you bring in, but that you bring something with you, that is how we do, science is a personal and social endeavor. how we do, science is a personal and social endeavor. So all I did say, I think, was I reduce it as much as I knowingly can. That's what you said. So what she's saying is there's no extent to which you can actually know because the holistic person that you are,

you are inexorably tied to your philosophy. Except. Even when you try to divorce yourself. So you guys are talking about a philosophy like, and I think this is fair because I think a lot of people do this, like it is a political position. But I'm talking about something, not just a, I'm talking about the way you view the world.

More comprehensively. Do you remember the show? I like that. The X-Files. I like that. Of course, man. Best show ever. The X-Files. The X-Files. I'm watching the show, do you remember the show? I like that. The X-Files. I like that. Of course, man, best show ever. Okay, the X-Files. The X-Files.

Yeah. I'm watching the show, okay? And there's like the skeptic science. Scully. Scully. And then mold, molder. Molder. Molder, molder.

Moldow? Moldow? Excuse me, molder, molder. And I've watched them interact, and I'm thinking, no, no. Okay, there was some glowing mass in a vestibule, okay? And Mulder says, oh, this must be an interdimensional. He just goes right to the most wild explanation for it.

And Scully is saying, this can't possibly be real. It must be a projection. And she's all discounting of it because it doesn't fit her philosophy that that can't exist. And I'm telling you. You're making my point for me right here, right? Good. Good.

It is the chemistry of those two perspectives that leads them to certain discoveries and so on. You call that, they look pretty immiscible to me. How's that for a chemistry word? That's good. You remember immiscible? Immiscible. Oil and water, immiscible.

Yeah, don't mix. You know how to missel them? I do not. You take a little bit of, because when you're making. Are we talking about sculley and molder? Yes, yes. How do we do it?

Oh! How do we get the vinaigrette? I learned this in chemistry class and then applied it at home. So you have oil and vinegar, and you shake it and it'll still separate. It's together for like a few seconds. But you can get an emulsifier to put in there

and it'll connect chemically to both sides and bring them together. How? So I think, if I remember correctly, a little bit of egg yolk will do that. Egg yolk is an emulsifier, that's right. I know that from baking. Believe it or not, yeah, I was going to say, egg. Egg yolk is an emulsifier, that's right. I know that from baking. Believe it or not, yeah, I was gonna say,

egg yolk is used as an emulsifier in a lot of cooking. So it brings it together. So they needed egg yolk. Fair enough. But I mean, even- But I like what you're saying. You're saying this is not philosophy in terms of, I believe, blum, blum, blum.

It is philosophy in terms of- How do you know what questions are good questions to pursue? How do you know when your apparatus is measuring what you want it to measure? Stuff like that. Let's anchor this back in time. Please compare for us the philosophies of the two greatest physicists there ever were.

Okay, so. Who do you think they are? You said this, so I was gonna say. So he's talking, so one of them has gotta be Isaac Newton. That's gotta be one. Yeah, Newton and Einstein. So tell me, because clearly you've studied this,

because you're writing about the man and everything. So and I love the fact that we share sort of access to history and what that means in the present. So I just wanna know, how would you characterize Newton's philosophy relative to Einstein's philosophy? Before I earned enough money to buy an actual book from Isaac Newton's days, I got this paperback called Newton's Philosophy of Nature.

Okay? And the paperback. Selections from his writings. And it's not only from his great books, but also his writings. Yeah. May I? No.

Oh, that's just a paperback. I thought, I was thinking of. It's not your original. I thought it was my original. It's not your original. He's holding it like it's a teddy bear or something. This means something to you. Yeah, but see, I've been all over it.

You've been up in it. All the pages are dog-eared. I've had this since middle of high school. So me and Newton go back. And don't you bad mouth Newton in this office. No, I'm not going to bad mouth Newton. I love Newton. He's a primary source in my philosophy of space

and time class. Because students. That's a class you take. I want to take that class. I would love to have you teaching it in the fall. Also, Einstein as philosopher is a course I'm teaching take that class. I would love to have you teaching it in the fall. Also, Einstein as philosopher is a course I'm teaching in the fall. Anyway, Newton was motivated at least

in developing, by many things, but in developing in particular his theory of gravitation in an essay called De Gravitazione, I don't know how to pronounce the Latin, but there it is. He's responding to Descartes who had three laws of motion. But Descartes thought that all motion was relative. And so it is in developing his response to Newton, to Descartes' theory of motion,

entirely on philosophical grounds, he is reasoning from his armchair how he can understand motion in a different way. He must have had a badass armchair. He did, he also invented the calculus from that same armchair. Einstein is responding to Newton. He was bothered by the fact that in a fully physical

worldview that Newton said he was presenting, you nevertheless had a background space time that was influencing matter but not itself able to be influenced by matter. This asymmetry of dynamics bothered him. So let me restate what I think you said. That Newton is describing a universe embedded within space and time.

Sort of a theater background in which matter. A theater set. Yes, okay. And so whereas Einstein wanted the theater set and the players in the theater to interact with one another. That's right. And in particular, Newtonian mass is inertial mass. It's an intrinsic in the old school philosophy tradition.

It is a property that belongs to the thing in virtue of the thing itself. This also, mass. Yeah, just remind people, you know, Weight Watchers is really mass watchers. Right. If you want to weigh, let, just go to the moon. Thanks, Oprah!

There's a lot of ways to weigh less. And so. But how do you get the money to go to the moon in the first place? But yeah. I just wanted to just clear. So when you reduce your number of fat cells in your body, giving it up to energy, then you're reducing, it's a mass you're cutting from yourself.

Yeah, it's supposed to be some deep essential, probably meaning essence of the thing. This also bothered Einstein. He didn't think that things should have innate properties in this way. And so one of the things that motivated in going from special to general relativity was a paper he wrote in 1913 where he predicts

gravitational waves, by the way. So he didn't want mass to be something that just belonged because God decreed it thus. And so he developed a way of accounting for mass that was also dynamical. We give something inertial mass because it's following a geodesic. It's following a particular path through space-time. And that is why we call something having inertial mass. It is not an intrinsic feature of the thing itself.

A geodesic on Earth is a path that you would take where if you sliced through that path, your slice goes through the center of the Earth. So it turns out if you do the math, it's the shortest distance between the two of them. So that's why you see on a map, you see these loops that go back and forth. They have arcs.

If you made that a sphere, that would be the shortest. We call that a geodesic, meaning Earth, but now you're taking it and using it for the whole universe. Because another thing he was doing in this 1911 in these papers when he's developing what's called the Entverphe, like the in-between theory between general and special relativity. He's working toward general relativity,

publishing along the way. And he's realizing that the effects due to acceleration are the same as the effects due to gravity. So acceleration and gravity are like two sides of the same coin. So as, even every time I hear it, I'm like, this is so brilliant. It's bananas.

It's awesome. It's simple and brilliant. But he was motivated by Newton's account not answering his why questions. This asymmetry between space and time being this God-ordained theater in which things happened, but the things themselves couldn't affect space-time, was a principal motivation for his wanting to dig deeper

and come up with a theory of space and time and gravitation that wasn't ordained on high. But sort of. Didn't he apologize to Newton? I have no idea. Somebody. Did Einstein apologize to Newton? I, I.

Perhaps in jest. I have a memory because his whole general theory of relativity supplants Newton's gravity. That's right. And I think he apologized at some point. Well, it's gotta be one of those sorry, not sorry. Yeah, I was gonna say, is it like the way you apologize to Pluto? I mean.

It was like you can also apologize to somebody while saying, but I did a better job, right? Like, he's still clearly appreciating. Sorry for blowing you out of the water. But also, you know know we're building on the people who came before us in developing our viewpoints of the world So he owed a great deal to Newton so this started with Descartes is what you're saying Descartes himself took three laws of new motion from kept like it Kepler's This thing had this game had been going on for a while.

Yeah. Yeah. From a philosophical standpoint, all of these are philosophies. If you mean it in the sense that they're trying to ask the deeper questions of why do the things that I observe behave the way they do. Yeah, yeah, yeah.

Why does Newton have only three laws of motion and not four? Or two? or 10? He thought that three laws of, he describes this in the General Scholem at the beginning, which is all philosophical arguments for why he thinks absolute motion can be differentiated from relativistic motion.

And he needs relative motion. I'm talking about Newton. Yeah, Newton, the General Scholem at the beginning. You said relativistic. I meant relative motion, I'm talking about Newton. Yeah, Newton, the general scholar in the beginning. You said relativistic. I meant relative motion, I'm sorry. From Cartesian or Descartes' relative motion. He thought that that's what he needed to give all of the account of all the motion. We come out of Newsy, we go through Einstein, and these are still, they still make sense

even if they're weird. You can still see why they make sense mathematically. But you go into the 1920s, and then quantum physics descends and nothing makes sense. But it works, it works, you can make predictions, the understanding of the periodic table of elements, of molecules, of atoms, all clicks into place, and everybody's scratching their head.

So what does a philosopher do then? All the things. It's so much fun. Yeah, so. You just like it when we don't know what we're doing. No, no. I think we would say that all of physics involves interpretive moments,

but they're particularly painful. In the case of quantum mechanics, and it's fascinating, let's go play. Like, let's go talk about it. There's a word for that, it's called sadomasochism. It's like, it's particularly painful. Yeah, let's get it. Yeah, but I mean, but it's also like,

these are the questions that keep you awake at night. There's pain, but joy. Yes, so. So, it didn't come out of nowhere, right? I mean, there was an old quantum theory that Bohr and Sommerfeld, who was a physicist in Munich, had been working on in the 1910s to account for atomic spectra.

Zomerfeld or Sommerfeld? Sommerfeld. Sommerfeld, I pronounced it in a German way. Excuse me. Okay. I saw an S there, so I just said Sommerfeld. I had one of his books. Yeah, yeah, yeah.

He was really important. I saw an S there, so I just said Sommerfeld. I had one of his books, yeah. Okay. Yeah, yeah. He was really important. He was also the doctoral advisor of Heisenberg and Powley and a lot of these guys who went on to be important progenitors of the new quantum theory. But they were trying to understand these empirical data, right, the spectrum. Every one of these people got a Nobel Prize.

Every one of them down the list. Einstein's Nobel Prize was not for relativity. It was for the photoelectric effect, which was dealing with quantum. And Brownian motion. And Brownian motion, yes, that's right. Brownian motion, which is to do with getting macroscopic about quantum effects.

Wow. But yeah. So Brownian motion, you suspend a particle. Like a pollen grain, like pollen. You put it in a fluid and it just bounces around and that wasn't fully understood. Like what's going on? It looks like it's random motion.

Right, right, and then you have to calculate, there's particles hitting it that are smaller than it, that are hitting it. And you realize there are more molecules of water in a glass of water than there are glasses of water in all the world's oceans. And we didn't have insight into that until Einstein explained Brownian motion.

To understand what the hell is going on in there. Yeah, we don't know the insides of atoms very much yet. Like there's so little known about the structure of atoms and so that's partly what they're debating and part of what allowed Heisenberg and Pali and some of the people working at the forefront in the 1920s They were looking at these description you remember boars planetary model of the of the atom right like part of why we call them Oracles yeah, because it right he made it look like yeah, but there are huge mysteries with this model It doesn't account for all these of all the spectrum spectrum the data of the spectra Or orbitals. I mean, yeah. Orbit. Right, right. But there are huge mysteries with this model. It doesn't account for all the spectrum,

the data of the spectra they're seeing. I'm using all the right Latin plurals here, I hope. But also, how is it that it jumps from one energy level to the next, and it does it discretely? That's right. It does it quantically. There's no actual physical motion from one place to the other.

What does the philosopher say about this? Yeah. Well, they were, Bohr and Domerfeld in the old quantum theory. You've been sitting here for half an hour. I'm about to deliver the crudegraph if you would shut up for a second. I'll do respect, sir.

All right, Elise, finish him. Yeah. They were trying to describe the electrons using classical terms for particles position momentum Heisenberg said what if we use totally different things to describe the electron? What if we try to write down instead of equations of motion in this classical way? We think about the electron in terms of way like by writing down the intensity by writing down the amplitude like a like a wave Yeah, sort of but he didn't use quite that language, but he said let's look, he used what's called Fourier,

like F-O-U-R-I-E-R, another French term, Fourier, analysis, to look at it. And he got these equations out that worked. And it was only by sort of stepping back and saying the language we're using is presenting to us a world that is a classical world.

That's a philosophical pivot. It was a new, it was a new approach. It was a new lens for looking at the problem. It was a new lens for looking at the problem. It was a new lens for attacking the problem. Right, because if you believe, or you think, that these other metrics are what actually matter, and if they don't actually matter,

you're gonna get the wrong answer. And Schrodinger continued to argue, like he developed wave mechanics in 26. Heisenberg did this in 1925. 1926, yeah. Yeah, so right on the heels of this, Schrodinger gives a description in terms of wave, and everybody knew, we love waves, we see waves everywhere, sound waves, water waves,

we understand how waves behave at the macroscopic level, and so when Schrodinger gave a version of quantum mechanics that was all written down in terms of waves, people said I can visualize that, I can understand how to model that. But it didn't quite do all the things Heisenberg's matrix mechanics did. But they were arguing about these viewpoints

in a philosophical way. Like what do we need when we have a full scientific theory? Do we need to be able to visualize in space and time what's going on or do we need the right equations? All right, so they did their duty and we're now 100 years later. We are, 100 years on. There's certain quantum questions

that the layperson sees unanswered over that entire century. How can two particles be entangled? What does that even mean? Right. And how is it you observe it over here and then instantly, it's not even the speed of light, it's instant. And people wanna wrap their head around this,

and you have not given us an answer to it. Yeah, at least what's happening. We haven't figured it out yet. It's an ongoing puzzle. It's an ongoing conversation. In that case, you're forgiven. Maybe it's not something to be figured out, it just is. Here's where this matters.

No, no, no, no, no. No, I'm just, I'm saying, maybe you're trying to bring a classical sensibility to something that has a different reality. I agree with you, and I get a lot of shit for that in the philosophy community. I think a lot of the interpretations of quantum mechanics that are proposed are trying to tell a story about how we get from a probabilistic set of solutions to an actual solution,

and I think the world just makes a choice. There are some dynamic considerations in there. It's a much more nuanced story than what I'm giving you right now. But I think you're right, that we're still very much moored to these classical. Pictures of the world. Classical pictures make sense in an armchair.

But you start saying particles pop in and out of existence and tunnel, they do this and that. And I, as a scientist, as an astrophysicist, I accept what quantum physics does for me to understand what the universe is doing. And I've learned to not lose sleep over trying to understand why. If you were working in quantum cosmology,

you would want to know, because we don't have a theory yet that brings together general relativity. When the large are small. And quantum mechanics. And in fact, most of these interpretational debates are happening with respect to non-relativistic quantum mechanics.

But we know that the final theory, we think, will be relativistic. It'll be a relativistic quantum field theory. So you foresee philosophers helping the physicists towards this goal. I don't, I mean, having a conversation with, I would say, and I would say the physicists are also having this conversation.

So for instance, there's a real question as to whether certain inflationary paradigms that are thinking about how we get to effectively classical field modes for the different parts of gravitational field modes or matter field modes, whatever you want. But we think the initial state was a quantum one. So we need to know a story about how we get

from a quantum state to what looks like. That's right. Because you're saying that if there is a model that makes sense, it started with the field. It started with kind of like what we would call nothing, but really it's everything all at once being nothing and then out of that, pop, and then boom, and then all of this.

No, it's everything everywhere all at once. Oh, I'm sorry. You left out one another. I gave a talk on entanglement that was about that, like had that title, but I watched the movie on the flight and had to cross that title out. I was like, oh, that's not quite what they're doing there. But some of the questions.

If I understand you correctly, we went from a quantum state to a macroscopic classical state, and there had to be a transition somewhere in there that allows us to bring these sensibilities together in a coherent understanding. Well, even when we're trying to understand what the universe looked like in those early stages before we got to the big asymmetric distribution

of matter we have now, those are stories that rely on our understanding how we get classical field modes, classical values for field modes out of a quantum soup. And so these questions show up there Here's another are they being answered by your brethren or by they're not being answered by anybody anybody We're talking about them together And there are you know some cosmologists who want to understand like these are they're asking whether or not we can have Whether we could find residue of entanglement from this early state and that's where I say even as a philosopher

find residue of entanglement from this early state. And that's where I say, even as a philosopher, no, because entanglement relations are going to be so damped down by interactions with the gravitational field mode and all these others, that we could never measure them. But that doesn't mean they're not a part of the story. So we're having conversations with one another about these things because the answer is unclear.

All right. Well, there's the mysteries mysteries you beg to answer. I don't know, I don't, give me my gummies. Give me my edibles, please. Get my edibles right now, cause damn. You know, I'm a philosophy professor, I should be on board, like, I have the worst, I've had the worst experiences, I just can't do it.

People around me just- There are no edibles in this office. Yeah, there we go. Okay. People are like, is your color red the same as mine? I was like, yeah, Hobbes thought about that too, like who cares? You know, let's go on through that. Leviathan Hobbes?

That Hobbes? That same Hobbes. Yeah, we all thought about that. Not Calvin and Hobbes. That's the Hobbes, Hobbes is, Calvin is named after John Calvin, which is, you know, John Calvin. John Calvin.

And Hobbes is named after Hobbes, the. Calvin as in Calvinist. Calvin and Hobbes is named after John Calvin, the Reformed the know, John Calvin. And Hobbes is named after Hobbes. Calvin as in Calvinist. Calvin and Hobbes is named after John Calvin, the reformed theologian. And Hobbes is named after the philosopher and political theorist, Hobbes. And how about the tiger? The tiger is Hobbes.

The tiger is Hobbes. The tiger is Hobbes. Oh, I've forgotten that. This is super important. Now who is Marmaduke named after? No, thank you, that's the one. This is beyond my realm of expertise, y'all. This is beyond my realm of expertise.

All right, we gotta learn this plane, but this has been highly confusing. Simultaneously enlightening and confusing. Is that possible? I have to say. Do you have a word for that? To be enlightened and confused at the same time? To be a philosopher.

Oh, no! Oh, full circle people. Oh, ay-ay. That's how you do it. Full circle. Well, let's keep talking about it at some point. Not now, you have other things going on. So that brings us to a close.

Sorry we didn't fully answer everybody's questions. Well, there are not. The answers are out there, Scully. No. The answers aren't known yet. No, you know't known yet. That's the beauty of it. Seek and you probably won't find. Seek and you will find what's maybe not the case. Oh, that's a good one.

I like that. It's popular. Seek and you may find the answer to the question you have not yet posed. There you go, ooh. Oh wow. That's juicy. Let me tell you something, Jesus is happy

he didn't say any of those things. People would have checked right out. Like antsy. All right, what fascinates me most about the frontier of science is to do it right. Yes, you gotta keep at least one foot in the perimeter where we at least think we know what's going on, and then you put the other foot outside

and test the waters for new ideas, new perspectives, new ways to think about how the universe works. But for me, it may be a specious goal to believe that the more you do research, the more you understand about the universe, because what remains true is that as the area of our knowledge grows, so too does the perimeter of our ignorance.

And if that's true, that might mean that science is indeed the endless frontier envisioned by Van Aver Bush in 1945. That is a cosmic perspective. Thank you, Elise Kroll. Thank you. Yes, thanks for coming down to share some of your vision and expertise with us here.

Yeah, it was great. All right, Chuck, always good to have you, man. Always a pleasure. This has been Star Talk, the quantum philosophy edition. Neil deGrasse Tyson has always bidding you to keep looking up.