Transcription
I have [music] yet to see a PhD in a philosophy department contribute materially [music] to our understanding of the physical sciences. Saying that something is only important in as much as it contributes to science [music] is a really dangerous point of view. When Einstein wrote an obituary that everybody read for Mach, he said, "One of the reasons I hold this [music] person in such high esteem as a physicist is because he kept asking about what is the proper goal of science [music] and that guided how he did science." And when we have conversation, it's interesting because I change the [music] way I think about how physics is being done right now. I learn about what they consider the interesting questions. It is worth doing in its own right. [music] This is Star Talk. Neil deGrasse Tyson. You're a personal astrophysicist. Got with me Chuck Knight. Baby.
>> Hey. Hey. Hey.
>> Lord of comedy.
>> That you know that sounds so
>> it does sound
>> like pretentious.
>> But people call you Lord nice. And so why not run it run its course
>> because it sounds like I should say I am the Lord of comedy. [laughter]
>> Like when people are like Lord nice that sounds kind of cool. You know what I It sounds like a like, you know, a term of endearment more so than a title. The way they say I got you. I got you. But when I say it, it's just like bow down before me. [laughter]
>> Bend the knees.
>> Exactly. Will you bend the knee before the lord of comedy? [laughter] Laugh not, I say, but capitulate. [laughter]
>> We're revisiting the philosophy of physics.
>> All right.
>> All right.
>> Couldn't get enough the first time.
>> It triggered a lot of interest.
>> Okay. more than I expected or anticipated. Of
>> course.
>> And so
>> a lot of people like philosophy.
>> I think so.
>> Did you [ __ ] today? [laughter]
>> Are you plan on bullshitting?
>> Well, we have an authentic philosopher in the house once again. At least crawl at least. Welcome back to Start Talk.
>> Hey everybody. [laughter]
>> Have you bullshitted today yet?
>> Yes, but not about philosophy. [laughter]
>> All right. All right. Good answer. So, let's remind people. Good answer.
>> So, you're [clears throat] associate professor of philosophy at CUNI City University of New York, City College. Uh, my father was an administrator there many moons ago. And I your background is entirely in physics and philosophy. And I think there's some math in there too. Is that right? Or was there
>> There's some history. Oh, history.
>> I was one class away from getting a minor in math and I decided to take tap dance instead. And no looking back, man.
>> Right. Great. No. You got to move that body. move that body. And no, [laughter] so I love this. And you have a specialty in the history of quantum physics. Is that
>> the history and philosophy of
>> philosophy of quantum physics? Cuz that there's a lot of room to philosophize there, let me tell you. Yes.
>> Cuz you know, we I'm happy to just calculate, but somebody's thinking about why. [snorts] And I'm glad that's not me. Somebody else is doing that. And so part of why we we have you back on, I'm reminded by not only my producers, but the comment thread that I might I might have been or was certainly over exuberant in my conversation with you way beyond what is normal. Maybe I I had like a lot of thoughts and feelings and and but you're the guest.
>> That's hard to believe.
>> No, [laughter] hard to believe that I Look, I'm going to choose to understand it as I mean, you guys have a great rapport.
>> Uh, and what I do is intrinsically interesting. So, it gets we were all in it. We were in it.
>> We were I was totally in it, but I want to make sure cuz I'm an educator first
>> and I want to make sure that people
>> come into this conversation [snorts] more thoroughly informed and so that they can become enlightened.
>> I appreciate that, Neil. [clears throat] Thanks. So let's just at the risk of sounding too pedantic tell us what philosophy is.
>> Let me be more precise.
>> Okay.
>> What is philosophy today
>> compared with maybe a 100 years ago, 200, 300 years ago back to to Aristotle and the famous sort of uh Greek philosophers,
>> right? So I I hope I won't be repeating like the same stuff. I only have like three jokes and I think I did two of them last night. We got other jokes coming here, but we're good. We're [laughter] good.
>> Fresh. Um, but that's maybe actually to the point. Um, some people have famously said that everything is just a footnote to Plato. Like it's all been done. All of the questions have been asked.
>> Um, but one of my favorite definitions of philosophy comes from philosopher of science Basin Frazzen. Um, [snorts] who also
>> name [laughter] Basin Frozzen. It sounds like a hogen ice cream. [laughter]
>> Well, that's true. Well, you know what? Hogen. Yeah, they made that up. the lots on the road like they're like let us sound European to sell our pecan [laughter] ice cream made in Jersey is legit Dutch which is like part of my heritage right um but he says that philosophy it might be asking similar questions but every time you ask it you're in a new uh context
>> new scientific context new cultural context new political context and you're a different person asking it uh and so there's a way that every time it's done it's done a new
>> and you could be a different person from yourself having asked the question even just a year or two earlier. I think one thing um we we tend to look really hard for coherent thought across a person's lifetime but why should we expect that right shouldn't
>> we shouldn't right people change their minds and people who think hard are the ones who change their minds the most because I think there there's a bit of humility there so yeah people um so Aristotle defined metaphysics right after his book physics and for him they were similar things they're asking about what kinds of things we encounter in world, what the what their behaviors are, what the patterns are that we see. And that's still a decent way of talking about what science is. It's explaining natural phen like physical phenomena, right? Understanding their relationships and their behavior and their patterns and all this stuff. Um, so they started together as the professions became a bit more
>> [snorts]
>> um spec specified. Um, they started specialized specialized. Yeah, thank you. That's the word. uh they um they they they teased apart a little bit but even into the early 1900s you have all these really famous philosophers like Ernstmach and Einstein and Pierre Dw and Puankare and Lorent um who of mach one mach in a medium yeah that same mach
>> that same mach um they were philosopher physicists
>> go before them tell me coming through Newton and Hook cuz they they didn't call themselves physicists they were natural philosophers. So take me through that era before you land in the 1800s.
>> Yeah. So again uh Newton is building on Decart and Deart uh was sort of the worldview that was building on Galileo and Kepler and Capernicus but doing so in a way that wouldn't piss off the Catholic Church. So it's kind of a weird thing but he wrote his his magnumopus his great work is called the principles of philosophy. And Newton is criticizing that particular book when he writes the principles the natur the mathematical principles of natural philosophy. Wait, did I get the title right? I only just called the principia. So I've forgotten by
>> Yeah. Yeah. So So what you're saying is Newton's famous work postdates the cart's famous work and he's uh is he poking fun at the title and making it more of a of a product?
>> He's trying to replace it.
>> Replace it.
>> Right. This is what they build on it.
>> Yeah. So, let me get the right. So, Principia Mathematica, uh, naturalis. So, the ma in English, the mathematical principles of natural philosophy. That's the full title.
>> In principles of philosophy, there's four books. Decart, right? There's four books. The first one is setting up his philosophical worldview, his epistemology, which is theory of knowledge. How do we know anything in the first place?
>> And then his metaphysics, like what is there that exists for certain? And that is considered the first thing to do before book two which is his physics. So in order to even get to the physics you have to talk about when do we know something
>> which is which book has the I think therefore I am
>> that is in the meditations which was published a few years before and he
>> was already trying to go there.
>> So book one of the principles is like a polished version of the meditations. All right. Um and that's what starts his philosophical worldview is the first book and then his physics and his celestial mechanics and then onwards. The principia begins with definitions which um arguably Pankare argues are um not helpful and there's a way that that's true. Um and then there's the general scholium which means explanation and the general scolium is where he gives his philosophical arguments for absolute space and absolute time and it is after that philosophical framework is established that he deres the three laws of motion
>> and gravity would [clears throat] come in there
>> and gravity is even later down the line but the first thing that they considered having to do was
>> talking about how we know how you know what you know. Okay. So
>> and then do you know that you know what you know and is it important to know whether you know if you know you know or right
>> I don't know I would say [laughter]
>> which is right
>> did you give the right answer to that
>> yes
>> okay so through that period the various folks who are trying to do physics are are fundamentally conjoined with philosophical foundations of why they're thinking that way at all.
>> Right.
>> Okay. So now fast forward or slow forward into the 1700s. Now take us to the 1800s.
>> Scientific revolution time. Also actual revolution time for a variety of countries. Um also
>> America.
>> Yeah.
>> America.
>> America and and of course France.
>> France. Liberty fraternity.
>> Libert. That's right.
>> Tobacco. [clears throat] [laughter]
>> Wait. I don't know. I don't know how to say tobacco in French, which is probably a good thing. [laughter]
>> Keep your stinking freedom fries
>> because we didn't like the idea of a monarchy. That's our history. Rebelling against a monarchy.
>> Um anyway, um
>> I see what you did there. [laughter]
>> They're writing to each other and corresponding and setting up experiments. Boil Gassendi um Newton Linets um the the people who were still philosopher physicists in the 1700s and 1800s they're also now working with Newton's Prancipia and it's known pretty early on that the Prancipia doesn't answer everything like the law of gravity is action at a distance because it just says if I mean imagine on a universe with nothing in it if two masses just popped into existence they would somehow immediately feel the force between the two, right? Okay. And there's no like time for the force of gravity to travel and say, "Hey, other planet, this is what you should feel toward me." Um, no, it's instantaneous. So, people knew there were issues. And one of the main people was Emily Duchado, who wrote a book called The Foundations of Physics.
>> Oo.
>> Right. So, before, you know, maybe
>> when was that? I'm I'm gonna pick that up.
>> She's in the mid 1700s. Thank you for that.
>> And she's experiencing a renaissance right now. For a long time, she was just known as like Voltater's lover and mistress, and she hosted many salon. [laughter] [screaming] Salon,
>> this is how I feel about [laughter] I don't know. I don't know how to say French things.
>> I just I want to just make sure the timeline is established here. So, Newton's greatest work was done in the 1600s, spilling spilling into the early 1700s. Volater comes around mid700s.
>> A little earlier. Yeah.
>> A little earlier, I think. And so, and you're
>> and Duch is the same time.
>> Data. And so, they're they're coincident in time.
>> That's right. Yes.
>> And she's so she's hosting a lot of the intellectuals of the time and like they're having an interesting conversation, but she's also in charge of teaching her kid, her her son, uh, physics, and she's disappointed with all the textbooks. And she she does what many people do. She writes her own. And the first thing she does,
>> as one does. Did you do that with your kids too?
>> See all the textbooks my kids are reading. [laughter]
>> They're all wrong cuz I wrote them.
>> Do you put as like the by line is like Lord of comedy, [laughter] your father. Yeah. Anyway, um she before writing this book of foundations which again starts with a philosophical framework and goes from there. It starts with the principle of sufficient reason and the law of non-contradiction and the rule of like sort of proper reasoning.
>> Wait, law of do are they declaring that it's a law?
>> It's an axiom.
>> Okay.
>> You have to start somewhere. So,
>> okay. So, you laid out some rules, rules and regulations.
>> You got to bite the bullet somewhere
>> and and what follows derives within those constraints. Okay. Gotcha.
>> So, but she's also the one who translated the the Prancipia into French. And I guess like current French physicists still read her translation, but she didn't just translate the Latin into French. She filled in gaps like she wrote a thick commentary.
>> And so it was her physics train pull out Newton say Newton, you need help. Here's what you left out. [laughter]
>> Exactly. And so it was people kind of got it like he's not telling us everything. He's given us some parameters, but there's more work to be done if we want to really know why things work the way they do. So um
>> and and how many lady physicists existed at the time?
>> Hard to know because again this physics philosophy split isn't totally there. So while there were just a few women maybe who were doing experiments of any kind. Um I'm not sure I know any. There are a lot of women doing philosophy.
>> Wow.
>> Corresponding with Linets, corresponding with Hume, um interacting like writing influencing livets's thought. Interesting cuz I have a book which is Linets's letters
>> and and there's all manner of people
>> that are on the other side of those letters. I I'll take another look at them. Why we all know liets today. Just tell Chuck
>> Newton both developed calculus more or less at the same time which I'm sure you woke up this morning saying you know what I'm dying to know [laughter] who invented the calculus at the same time as Newton. But anyway um he thought that space was not a substance. It wasn't a thing. it was just the relationships between stuff, okay? A [snorts] relational view. And so he objected to the idea of Newtonian absolute space and absolute time, which is not really a stuff either, but it exists independent of matter. So it's like a thing in Newton's ontology. Like when he's listing the stuff that exists, space is there.
>> Space is part of it.
>> But for linenets, it just is how we understand the difference between the the distance between matter. I'm confused.
>> Yeah,
>> there are two independent calculus and they both work. [laughter]
>> They sounds you know they're different because all the notation is different.
>> Yeah.
>> And in physics we retain a lot of Newton's notations. Okay.
>> But in pure math it's all libnances.
>> You know the integral signs and all these squiggly symbols. That's liance. Yeah. It's all liance. And so liance is a little more elegant than Newton. Newton was like let's get in and get the job done and get out kind of thing. Right.
>> But I'm [clears throat] impressed that that it would happen at this basically the same time and independently.
>> I love calculus. I don't know why people give it such a bad rap.
>> I didn't No, you that's the thing I never thought I'd HEAR THIS MORNING. [laughter]
>> I love when I woke up this morning. That's what I thought I'd never hear.
>> Is that a bumper sticker on [laughter] your car?
>> I love
>> I don't have a car. What if I did? That would be one of them for sure.
>> All right. Nope. That's lame. [music] Mhm. Ready? Do you harbor questions about the universe, some longheld bit of cosmic curiosity lingering within [music] you or questions about anything at all? You can become a Patreon supporter of Star Talk. You have access [music] to our exclusive question line on our website. Those are where we draw our questions for our [music] cosmic
>> some of the most extreme objects in the universe. Star Talk is a work in progress [music] where we every month come up with some new way, some new idea, some new understanding of how to bring the universe down to earth and we could not do that without your support. Thank you. And as always, keep looking up.
So now we got them. Now take us now into the 19th century.
>> As technology gets better, we get we're able
>> the industrial revolution.
>> Yes. and all these like we start moving from talking about forces and inertia and stuff we can't fully analyze. Um, and we we start getting quantitative about conservation of energy and about like tweaking frog legs so we can understand how muscles work and psychology is coming into its own and sociology is coming like the different fields start to distinguish themselves and at the same time like universities are being built and growing and the different faculty at universities are getting set up. um professional societies like the Royal Society and the Paris Society of Scientists um are growing. So now you have communities growing up where people share their findings and it's international at least in the west um and so on. It's it's a long and interesting story which I other people could probably give a better version of, but it's this increasing um ability to quantize uh and specialize. The more we learn, the more there is to sort of, you know, I was thinking the other day, wouldn't it be great if we lived at the time of the Library of Alexander? Because like you could really have said, I've read all the books in the world.
>> It's not possible.
>> I think at least I think that was true up until much later than that. Like in rumor has it I've heard I'm heard told that up through the 1500s, highly educated people could have claimed to have read everything that was ever written.
>> Yeah. Well, that's because it was all handwritten. real slow.
>> Yeah. But some people like Aquinas, they had scribes. They had like a room full of monks writing for them >> writing on as they go into these communities. When does all of this lead to what we are cuz
>> none of this stuff is cross-pollinating today?
>> Well, I I wouldn't say none of it is. I would say it's harder to do. Okay. And I'd say people are still asking these questions. Um, it's but we've built and we talked touched on this last time. We've built up our universities in a way that we actively discourage people from staying as general as possible. Okay.
>> Um liberal arts training is is being kicked like a a poor little puppy and it's like such an important thing.
>> Um and then when you get to graduate school it's all over. It used to be like you would try to say general even through your master's degree. You would take a little bit of like you would learn everything.
>> Are you saying it's important because it it just kept you loose?
>> Yeah. It kept you learning a bunch of other stuff. other stuff just the dimensions of life and of society.
>> So I mean I'm going to jump all the way to the Cold War era and if people are interested like there is good history on this and one book in particular is the physicists by Daniel Kevlas. It might be a little outdated by now but it just talks about the history of physics in the US and how it became so many different specializations and so on. Um, but it was only after the Manhattan Project and after World War II that physics was properly like considered a thing you could be have as a career. It wasn't just something you learned as a young man at the university or one of the few women. Um, but it was something you could have a you could bring home the bacon, right? If you actually did physics,
>> at that point, physics is making bombs. They're they're they're important for national security and no one is talking about philosophy at that point.
>> Um, [clears throat] so that's when the transition kind of happens. It becomes in the US very pragmatic. It's about the shut up and calculate mentality and that really dominates through the cold war era because there's this it's competition. Um, but interestingly in the 50s and 60s James Kant who was a president of Harvard and a physicist and a chemist.
>> I didn't remember that but
>> Konat um fought really hard for even his physics students to know the history and philosophy. He understood it as so important that he built it into Harvard's program that even if you were just studying physics, it wouldn't be like writing down lab notes and doing calculations. you would also take a history and philosophy of science course.
>> You're saying explicitly and implicitly that coming out of the 19th century into the 20th, especially postwar
>> Mhm. [clears throat]
>> the field of physics has has borders
>> in a in a way
>> where other ways of thinking can't get in.
>> Yeah.
>> And you're saying that's to the detriment of physics, not to the detriment of other fields.
>> How would you characterize that? I think it's the to the detriment of any field, not just science, when those walls become impermeable. Um,
>> I think walls are a very good thing. [laughter]
>> Stop it.
>> Physics, as far as I can tell today, still suffers from this border problem.
>> It makes sense because we're on we get hyper specialized because we know so much and we're building on so much. We're asking just that many more questions and we have that much more technology to explore. So I mean the blossoming of many flowers is a good thing.
>> So how do we use you? [laughter]
>> Well maybe I don't want to be used.
>> Okay. Okay. Sorry.
>> Maybe I get to be exist in my own right because it's a beautiful and wonderful human endeavor.
>> Came out wrong.
>> I know what you mean.
>> How do you help us?
>> Okay. We help each other when we share ideas when we um have conversations like we're doing now. So for instance, I was just talking about Mach. He was an important influence in Einstein. When Einstein wrote an obituary that everybody read for Mach, he said one of the reasons I hold this person in such high esteem as a physicist is because he kept asking about what is the proper goal of science and that guided how he did science. But what is the proper goal of science is like a guiding principle. It is itself a philosophical principle the same as we might say um at a more intimate level in physics like that choosing something that's parsimmonious or beautiful or simple or whatever there's no reason why the earth should or why nature should give a damn about those principles
>> about our aesthetics.
>> Yeah. Right. Um in fact that nature is uniform at all is something you have to assume to even think science is worth doing in the first place. It's like there are moment you have to sort of buy into certain untestable principles to consider science worth doing. But the thing is these are important things um but the concepts that we use too. So here's a good point. um space and time, the way that they're used in Newton, absolute space and absolute time, and whether or not they're important for his derivation of the three laws and his law of gravity and all this um was an important question to ask. But Mach and Einstein and others at the end of the 19th century are clear that electronamics isn't going to work um in absolute space and time. Like we they knew things didn't fit together in the right way. And so they knew that one way to attack this to get to new physics was not just going to be to push around the equations but to re-evaluate the basic concepts.
>> And just to be fair to Newton the whole electronamics the the physics that came to be understood that we call electronamics was not yet there for Newton.
>> Right. So he's working in his own like you said you work in your own world. You come up with what works. Later on
>> we keep going.
>> Yeah.
>> Right. So it you know 19th late 19th century there's there's some there's tension between these different like really these pillars of physics like thermodynamics statistical mechanics uh um and and and I'm blanking sorry Newtonian mechanics sorry classical mechanics um and it's Einstein Einstein says that it is not the physics in him as it were that allowed him to get to special relativity it was that he said what do we mean by this term simultaneous And what do we mean when we're talking about space and time in a different in different frames of reference
>> questions physicists typically ask?
>> Well, they were back then they were for the heroes of Einstein and the class [clears throat] of people who were philosopher physicists was a was a was a significant class of people
>> at the time
>> a century ago.
>> Yeah,
>> that's right. So the it's not that it wasn't for the last 50 70ome years is is partly because of like there are political reasons for it like the um the intellectuals who came to the US from Germany during the wars. Um the way that they entered into the academy and began to teach physics and philosophy and think about this stuff. There are whole classes at the graduate level you could teach just about why the Vienna Circle, a particular philosophical school which was all scientists influenced the way American philosophy and physics relate to one another. So it's a complex and interesting story. But the the end point is that if we take Einstein's word for it, this re going back and saying are we really understanding this concept the way we should be? And this is what we're doing right now with gravity and trying to understand the quantise of gravity and what we're doing right now with causality like is there a quantum notion of causality or what does causality mean if space and time are even crazier than in a relativistic framework. Um, so it's the reevaluation of these basic concepts and that is a philosophically motivated question and asking how do we know? We talked about this a bit last time. We're getting into regimes in physics where we're beyond what is empirically testable at least for the foreseeable future.
>> What then do you use? What are your criteria for judging what is better or what is worth pursuing? Where do we who do we fund? Where do we send our best graduate students? [snorts] that is that is based on who has the framework that you find the most compelling um whose view about the nature of space and time, how general relativity and quantum mechanics fit together.
>> So Brian Green's bestselling book, The Elegant Universe,
>> just in all fairness to him, that was not his original title.
>> What was it?
>> It was some more boring title. The publisher chose that
>> and that had a certain cache with the public.
>> Yeah. and and but it implies that we as scientists are in search of beauty um majesty and elegance in the universe as though it's waiting for us to discover it.
>> It's like the universe is going to a cocktail party. Darling, [laughter]
>> presumably that's still okay to look to have some prior expectation for the universe to guide your next questions.
>> Well, you shouldn't like it's important and unavoidable as a guide, right? And we sort of talked about this framework, this worldview thing, like it's going to be there. But elevating those guidelines to the level of dogma is when we get in trouble or just
>> because then it affects who you hire into department and
>> Yeah. But it also affects what you consider the correct route to go.
>> It it shapes your whole outlook on how you're going to approach everything, right?
>> You know, cuz you're like, well, can't do that because we've already made up in our mind that this is the way it's got to go,
>> right? Right. Or I mean you have to bet on a pony, right? I mean, if you're choosing whether you're going to pursue like canonical approaches to quantum va gravity like um loop quantum gravity versus covariant like gauge theoretic like string theory like what Brian Green does.
>> He's saying please.
>> I'm pretending [laughter] what you are talking about right now.
>> Different approaches to solving a problem that we know exists.
>> There are there are like two basic this is this is a very crass way to put it. forgive me, but there are two big approaches to how to unite
>> general relativity and quantum theory.
>> Okay, that's
>> and one of the approaches is trying to build a theory of everything from the ground up. String theory is kind of like that.
>> Heard that. Go ahead.
>> Okay. Uh the canonical approaches say we think quantum theory is is the most fundamental theory. So we're going to try and bring GR into that framework.
>> Gotcha.
>> But that is something we that is something we can never empirically prove which is the right path to pursue.
>> Okay. Why I I'm leaning that way?
>> Yeah.
>> Because no one has ever found a quantum physics prediction that was false.
>> It it it is so correct that oh my gosh. All right. But now you go to general relativity. It has known limits. It can't calculate the center of a black hole. It can't calculate the moment of the big bang. It fails. If you can't calculate, you know, stuff about black holes, get out. [laughter]
>> Get out of physics.
>> No, no, no, no. What I'm saying is
>> not people. I'm not talking about people. I'm talking about [laughter] abstract entities.
>> No, no. What I'm saying is if you already know people
>> If you already know the limits of general relativity,
>> right?
>> And you don't know the limits of quantum physics because you've never seen the limit.
>> So you
>> I'm thinking quantum is more badass.
>> Probably that probably goes in here, not the other way around. or or of course there could be a third entity as long from both.
>> Yeah. So, and then there are some alternates to these approaches and they're considered a little bit fringe, but that means like it's hard to get good grad students to come and build your and like there are sociological factors too. [gasps] But yeah, back to this notion of guiding principles. Some of them have been like huge issues in the history of science and I talked about space and time, but one of them is like objectivity, right? this idea that you you ask the person on the street what are the what are the adjectives that describe science and they're like well it has like a corner on truth maybe that science has like this corner on capital T truth um and there there are some philosophers and scientists who continue to say things like this but that's wildly problematic because that itself is a philosophical view like how would you know as one single person even um that that this is a special kind of truth now it's true that we have How true is it?
>> Empirical
>> like medium capitalist [laughter] like the slash is somewhere between
>> okay quasi
>> they're different size T's to begin the word truth
>> I'm going to say like you know 50 I don't know like 20 proof that's weak that is weak sauce anyway um objectivity is also one of the things that's supposed to make the knowledge and the truth that comes out of science a bit more
>> untouchable
>> um but objectivity is where the development of quantum mechanics gets you in trouble because if you mean objectivity to be something like when we do science we can rope off this realm or this system and we can poke it and pro it and study it and ask lots of questions blow it with hot air like see what comes out um and that's how you do phys like you have to assume that there's some divide between you your apparatuses that are measuring the thing and the thing itself this is a very old problem I think it's even a problem
>> it is and it's an old one except in the sense that Like Aristotle, I think, or somebody said like if you want to study a bird, you can watch it flying around in its habitat and singing and all that, but you also like need to dissect it and look at it, but you can't have them both really because if you've dissected the bird, you
>> you can't fly around anymore.
>> Well, you don't want that happening, right?
>> I thought that was Fineman a whole lecture on birds. Oh, then I I really don't want to quote Fineman for a lot of reasons, [laughter]
>> but I like what you said where if you really want to know what a bird is, you're going to have to open it up, cut it open, and then it's not the bird that you were studying, right?
>> You just influenced the thing you were trying to understand. So we know how to sort of quotient out that engagement in classical theories to a point that we can get very nice um predictions of like football trajectories and
>> hence the idea of an objective truth
>> right um but what happens in quantum mechanics is and Bor and um many others were realizing this already in 100 years ago right in 1925 when it was first developed that there's
>> 100 years ago we're in the centennial
>> that's right it is the 100th anniversary of
>> we we did a whole live show at Beacon Theater celebrating this centennial.
>> There's been a lot of celebrations. It's the international year of quantum. I'm just going to have like I'm going to have to sleep for all of 2026. [laughter] But that's when wave mechanics was developed and new physics.
>> Every year and and Hubble discovers that we're we're not the only galaxy.
>> Wow.
>> 1826.
>> There's always something to celebrate, right?
>> 1926, right? Mhm. There's a way when you're talking about quantum systems uh like photons and electrons and these things that you cannot avoid interacting with a system in a way that cannot be quotiented out.
>> And so this is something that Einstein continued to look for. Uh in particular he thought that when you're when a a physical theory is complete that means that you can give a mathematical state bjectively. That means there's a mathematical state that corresponds to some real system in the world.
>> Did you just use the word bjectively?
>> Yeah, sorry about it.
>> That's a word.
>> It just means in both directions like that that you can read from the math to the world or from the world to the math.
>> Interesting. That there's a nice correspondence
>> by objectively. Cool.
>> And I think somewhere else Schroinger says, "Yeah, Einstein, he likes a a map with a little flag on it saying here's this system and here's the system." Right. Um and because in in um Schroinger's wave mechanics you can't do that anymore. Um because once a system two subsystems have interacted quantum mechanically and we pull them apart and even if their interaction has ceased. Einstein says you should if you have a complete theory you should be able to give a state des a description mathematically of this guy over here that doesn't make reference to this guy over here.
>> Oh that's
>> they're totally separable. That's kind of a an issue, right?
>> It is. [laughter]
>> It is a little bit because entanglement can be understood as non-separability.
>> In fact, there it means there after there's a quantum interaction and it's a new kind of thing that it's not mechanical. It's not thermal like
>> you don't even have to like
>> it's a new thing.
>> It's a new thing and it's not just a new thing. It is according to Schroinger the thing that causes a departure between classical theories and quantum theories. When systems interact, something weirdly different happens and you can no longer talk about the system the the physics of one
>> without considering the other or referencing. That's right. Because wow, that's wild. It
>> is wild. I I I love it.
>> Okay, but in all fairness to the objective truth people,
>> they're really I don't think they ever intended to include quantum systems in it. You're talking about the macroscopic classical physical world, right?
>> Well, can can you have both? I mean c can you just isolate the one for for those circumstances and then have the question of the other like philosophically and I'll say physically is that possible
>> it is but even Einstein realized right away
>> that quantum theory if it's made if it's about the really small stuff what is the big stuff made of [laughter]
>> well yes
>> a bunch of the really small stuff right so there's a way that Schroinger's descript mathematical description of the quantum stuff that means you can't separate out systems that's part of it should also apply at the macroscopic scale. So there becomes this whole issue of how do we explain first of all what this theory of small stuff is doing and then what happens when we get to this level because at this level it doesn't look like you and I are entangled or anything like that right um and we can give really good physics explanations now for why that's the case um but a lot of people like mistakenly think that the Copenhagen Copenhagen interpretation like bore and the others that were so intent on recovering objectivity so we could talk about quantum science um made a sharp and fast distinction between the classical world and the quantum world. Like you have your measuring apparatus and that is a classically sized thing so that we as humans
>> a blunt instrument.
>> It's a blunt instrument. That's right. Um and then you have the quantum system that's that it's interacting with.
>> But in order for them to interact, they we have to talk about them in the same theory.
>> However, it aren't you allowed to say macroscopic objects all these wave equations average out and to get to this classical result
>> but we know better than it's not just a averaging out it's a process called quantum decoherence
>> what is that
>> entanglement yeah entanglement itself um when you well it's the same problem about objectivity but first of all I just want to clear the like bore never uh in in his postworld war II um popular extras and stuff he sometimes talks about a classical world but he never ever there's no evidence that he believed there was some really separate realm like it's a continuous ous situation. Thank you, Chuck. You're my friend. You're here for me. It's a continuous situation. And he's like, "Okay, it's continuous, but we still have to we are physicists and we go into the lab and we look at a a machine with a pointer. We we have to be able to talk about that." So, there's this pragmatic aspect of what he's saying. This pragmatic objectivity, it is the failure of our being able to give this hard and fast divide between the object we're studying and the world around it that accounts for why we can't see things as quantum mechanical.
>> Mhm. It's because the things the quantum systems we're looking at are in fact interacting with lots of other stuff.
>> Einstein said God doesn't play dice with the universe famously. Is is there are philosophers landing in a place where there is objectivity in quantum physics?
>> It depend.
>> I'm sorry. Are they headed to a place? Is that a goal at all? Well, if you mean objectivity as interubjective agreement, like that we could go into each other's labs and agree on the results of what each other see, then clearly yes, that's a part of what
>> Okay. Of course, cuz otherwise there's no science without that.
>> But I mean, I was at the 100th anniversary of quantum like Helgoland conference. Helgoland is the little island in the North Sea where Heisenberg went to do a wee bit of cocaine and to finish how to do uh
>> where do you get all the scoop on people?
>> And I'm going to tell you,
>> I read their letters. Oh, [laughter] the letter
>> cuz not in their books.
>> Yeah,
>> right.
>> Let me just say this one thing. Make a correction there. Uh there is no such thing as a wee bit of cocaine. [laughter]
>> You can't do a quantum.
>> Um so they got a bunch of physicists together. They had a panel session with a number like four recent Nobel laureates in physics and they're talking about the bell experiments which test entanglement and show that they're not communicating faster than the speed of light or anything like that. And it's something we call non-locality, which I would characterize as like the physi like the signature that we can measure, the signature of entanglement. That's a poetic way of putting it. These physicists won the Nobel Prize for designing experiments to test this and they could not agree on stage what non-locality meant about the world.
>> Okay. So tell us what non-locality means.
>> I'm not going to be able to supply an answer if two bell no lord. I think I think it's it's just indicate indicating that systems are quantum interaction is a kind of interaction we have never studied before in
>> okay so non-locality means these two particles that are entangled cannot be described independently
>> that's right
>> of each other so so this is not local it is connected
>> so it's not just that because we could do that classically right um if Chuck always wore different color socks
>> Mhm. and I saw just one of his socks on a given morning. I was like, he's wearing a brown sock. I could know something without measuring his other sock. I would know that it would be non brown or exactly right. Mhm. Okay. That's purely classical, not interesting. What makes it very non uh non-class is the idea that once these systems have for all purposes we believe stopped interacting, they're not communicating, there's no information going between them, nothing is exchanged. If we go if they while they're in flight, we can ever at our over at our measuring device for this guy set it to measure some quantity or other spin with respect to some angle or something.
>> Measuring a quantum property of that entity. Yes.
>> Yeah. Some property of that entity. Um and the other one will know
>> what what it is that was measured and what state the other thing is.
>> So therefore it's not local.
>> So right
>> that is the nonality. So it's not just that there's a correlation between the two. We have lots of classical correlations that we love. Um, but it's that these correlations cannot be explained. They the correlations exceed like just statistical randomness.
>> Can you one day?
>> But yet they can't be talking to each other.
>> Can you one day?
>> That's what There you go.
>> They can't be communicating unless you want to ditch the speed of light. And most people are happy to say,
>> did you wait? Like Chuck woke up this morning and said, [snorts]
>> I'm happy with the speed of light being what it is.
>> But at least why not go go full monty here and say the two particles are connected by a wormhole.
>> So there are we could give alternate explanations, but wormholes are way they would have other effects, wouldn't like they would
>> who knows it's it's a it's a entanglement wormhole. I mean, who knows? With a wormhole, you're not moving faster than the speed of light. You're just cutting through. Yeah,
>> the space-time continuum instantaneously.
>> I think it would be hard because entanglement non-locality is is is so ubiquitous.
>> Um I think it would be it's not impossible of course and this is where like your guiding principles come in but to just think that wormholes occur whenever but also entanglement is can happen with respect to different properties of a thing and it can change over time and it can be multiple systems depending on those. So it is a really complicated relationship.
>> Okay. So now I measure one of the particles. The other one manifests itself with the complimentary properties and now I've just de co they're no longer coherent.
>> Yeah. They're no longer entangled after you've done that measurement.
>> Okay. So now they're local
Particles. Yeah. [snorts] In fact, the measurement that you do, the physics that we're doing is all local over there, right?
Um, but yet there's this thing we can't explain.
All right. So my question to you is, is it the physicist who's taken a little bit of philosophy that'll help them address all of these questions? Or is it the philosopher who's taken a little bit of physics who might get us out of these conundrums?
I think we could use all the help we can get. Let's all who cares where it comes from. [laughter] All hands on deck.
All hands on deck. I mean, the way I'm sorry, I'm cuz I'm still, you guys were moving very quick and I'm the guy sitting [clears throat] here without any PhD of anything. Okay. [laughter] So...
You don't have a PhD.
Yeah.
Give this man an honorary doctor.
I [laughter] know. Yeah. Who invited you?
Okay. So based on what you just said, cuz I'm running it back in my head. Is it the actual measurement at the time of measurement that makes the entanglement, or, uh, if there is there ever a decoupling at all, or are they measured and then tangled and then forever entangled?
All of those things can be true, depend, like, so we could, we've developed ways to do weak measurements which sort of lightly tap the system. It's like, in a way, you can gather some information but not fully decouple it. Um, but and again, the degree matters, like there are some limits on how entangled certain numbers of states can be with respect to some, like, so it's this is why we can use entanglement as a resource and like to help us explore different, like, topologies in in in in holography, which is, you know, AdS, like Anti-de Sitter space, and how it relates to conformal field theories, which I don't really know about and I want to figure out, like, I got to get, but they're using entanglement as a way to probe unmeasurable stuff.
Okay, we got to land this plane. So, the way I want to land the plane is to get you...
That is super cool, man. I'm telling you, it's very cool. Unbelievable.
...get you to tell me what the future of this creative thinking will bring to quantum physics. Will it, is the goal state to turn quantum physics into something as intuitive as classical physics, where with pathways of understanding, it's obvious that it should do that this particle pops in and out of existence, of course, or will it just remain statistically mysterious and like Einstein said, "God does not play dice with the universe," but maybe God does go...
MY ANSWER IS DONE.
...maybe God is a gambler and just deal with it.
Yeah. Uh, people have a different, people have different questions about about that. So here's another, like, if you're a physicist who does quantum theory, uh, or you're, you're an experimental quantum physicist, and you believe that it, the universe is not statistical, then you're going to design tests that try to get beyond that. But if you think the world is ultimately indeterministic, then at some point you're going to move on. Yeah. Um, but I've already said, I think this is just my guessing again from conversations I have with practicing physicists. But thinking about quantum mechanics is never going to be intuitive the way classical mechanics is because we, as evolved creatures, the way we are, started doing science in terms of position and like with things we could see and measure and apples and arrows and...
...we didn't evolve in a quantum state.
No. In fact, you could very easily argue that knowing quantum theory is evolutionarily maladaptive because it's a bunch of nerds like myself sitting around doing problem sets, and here comes the saber-tooth tiger. So, it's good for us.
Oh, you would be summarily removed from the gene pool. [laughter]
Yeah. I PREFER A CLASSICAL. Good thing for physicists.
A classical understanding of the saber-tooth tiger wins every time. Yes. Okay. [laughter] If that's the only thing that the audience takes away, that's a good one for those who live near saber-tooth tigers. Um, they're extinct, right?
Yeah.
Okay. Biology is not my area of expertise. [laughter]
But, but I got, I got news for you. The regular tigers, they'll eat you. The regular [laughter] tigers.
They're good enough. Sharks and things.
They'll eat you, too. Plus, the, uh, they're on the list for becoming de-extincted. The fact that we can do that now. So [laughter] cool. Um, so there's a way that quantum is never going to be intuitive to us the way it is. But that's why engaging with these philosophical questions, we're going back and asking, what are we doing when we do this test? When we do tests, are there loopholes in the logic of how we're doing this? Are there things we can be testing we haven't thought of yet? Um, are we using the word causality or space or time or background? Like, are we using these in a consistent way when we set up our experiments? Um, are we testing our assumptions? Like, um, these conversations, while we're so wedded to the classical picture of things that understanding that...
...it's not our fault. We evolved that way.
...very natural, right? Um, but it also means that we have to do a lot of work to continue un-oring ourselves from that perspective. I like that phrase, un-oring. So, so...
Okay, all hands on deck.
...keep doing it.
No, it makes sense. I mean, it's like you're, what really, it's kind of a, you know, an oification that happens...
...that's another really good word.
...you know, because of, uh, the practice.
Uh, the practice itself.
And then what you have to do now is to, in order that we can become more elastic, this is where the philosophy comes in, to help change the thinking altogether so that we can go in a different direction.
Right. And in the ideal world, there would be more cross-pollination, but also the way we train physicists would be, I mean, because there are a lot, there's lots of philosophy that doesn't really talk about physics or take physics as its input, the way philosophy of physics does. You know, ethics, um, epistemology, um, social political philosophy, these are important areas of philosophy that leave [clears throat]...
...ethical philosophy, religious philosophy, even economic philosophy.
...philosophy of law, philosophy of the emotions. Like these things can stay.
Law, that's another frontier where they need some philosophers. I...
Really. Every time I, every time I meet a lawyer, I ask if they're a maritime lawyer, cuz they're going to be the first ones to like develop. They're going to [laughter] be the ones. Um, yeah. A good friend.
Has your satellite crashed into another satellite?
THAT'S NOT THE CAT.
NO, LISTEN.
We can [laughter] get you what you deserve.
That's not what we're talking about by space law.
Actually, it's not far away. I mean, [laughter] there's a nearest trajectory between Earth and the moon. Who's going to, please, is there going to be toll booths along that? Like, who's going to police? My brother is co-founder of of Carmen Plus, which is an asteroid mining startup, and they're, they have a lot of...
...everyone's brother would be. Yes, we all, we all have.
...and what they do is super cool. Um, but, um, but what they're, but they have to think about these questions, like, how do we, do we tax stuff that you mine from asteroids? Who owns this stuff? Um, these are really important questions. So yes, um, but that physics training in the US would involve some pausing and stepping back and looking at the history of the field and asking philosophical questions.
Is there a country that's doing that now, and we're lag, we're lagging behind them?
I think there are, um, I, you know, I don't know at the university level, um, but when this was, what was really exciting at Helgoland is I met a lot of young, like early career folks in physics at these great labs all over Europe, in China, and in South America, and some in the US, although to be honest, most of the labs in Europe are hoping to get some of our best scientists who are leaving.
Mhm.
Um, this is a real thing.
Phone calls have been made. Yes.
Um, we're losing some of our top scholars. I wonder what's going on with that.
But the young generation...
...wants to study the, they are interested in knowing these things because they understand how wedded it is to the, to the, the edge of physics that they're asking. So I think if enough people ask for it, like vote with your dollar, right?
Ask to be taught these questions when you're learning physics, and it will...
...a reminder that when you're young, you're a little more irreverent in your thoughts anyway.
Yeah. You're, you're, you're a little bit less, like, you haven't built a whole career in a particular groove, so you can sort of...
...hop over. All right.
Yeah. Yeah.
Well, at least thanks for coming back. Fascinating.
Thanks for inviting me. I, I, I have a good time conversing with you.
And you're just up the street. I mean, you're right up there. City College is up in 138th Street. Uh, right up there in Manhattan.
A few miles [snorts] north of here.
Can I ask one last question, Neil?
I guess so. Sure. I know you've said, this is personal and so it doesn't have to go on the air if you don't want, but I know you've said a number of things about philosophy of science and philosophy in general in the past, but your, like, you, you seem really genuinely curious about these things. What's that about?
I would say my, my comments on philosophy have been caricatured.
Okay.
Um, and so I can be very explicit...
...there.
Okay. I have yet to see someone who has earned a PhD in a philosophy department...
...in the 20th century...
...contribute materially to our understanding of the physical sciences.
Oh, it's been done already. Yeah. Um...
...I just haven't, I haven't...
...but also, I mean...
...so who, who was saying is the purpose, is the philosopher saying that, or is the physicist saying that?
The physicists have said that, like there are contributions.
What's the single best example? Oh.
Um...
...single best.
Adam's got one.
You're here.
No, [laughter]
I'm calling on my, ask a friend.
Okay. Ask a friend.
Phone a friend.
I got to phone a friend. Phone a friend.
So, Abner Shimon was a, was a physicist at Boston. Boston...
...was a physicist. So, his, he's formally trained in as a philosopher.
Abner Shimon has a, has formal training in physics and in philosophy.
But his PhD is in what?
Both.
What?
Well, there you go. He has two PhDs.
That's, that's the point. The point is when you read these papers, the reasoning is philosophical, logical reasoning.
Oh, I just, don't get me wrong,
Okay?
I'm not saying that physics can't be helped by philosophical thinking. I don't know any good physicist who isn't thinking on some level philosophically about what they do. Great. And in the field of astrophysics as well, good.
There's always a philosophical dimension. So the, the precision of my comment about philosophy has just been, what is the value to the physical scientist of someone who's got spent their entire career academic training...
...in philosophy. So that, so, and I compare modern times to how frequent those contributions came a century ago. And so if this is, this is one guy, maybe there's more examples, but I'm, I'm just contrasting...
Oh, yeah.
...the utility relative to what role philosophers played back in the day.
Yeah. So I said this last time and it's worth repeating.
Saying that something is only important in as much as it contributes to science is a really dangerous point of view.
Yeah.
That said, it's still contributed to science, but it, it is worth doing in its own right. But this, um, it is worth doing philosophy of science in its own right.
I'm not denying that either.
And I don't think it's also very, always quanti. I don't think there's a hard and fast line between these disciplines, which is why they were for thousands of years the same pursuit and why in some arenas we're seeing them coming back. Um, because...
I never said it wasn't worth pursuing.
...just been Shimonied. Shimon. [laughter] No, I never said it. I, I didn't, I didn't say it wasn't useful. As it, in its own field. I'm just talking about how useful it used to be to physics to have a philosopher in the room. And that utility is now absorbed by physicists who are thinking philosophically...
...rather than a person whose entire training is in the philosophical world. And so I just...
...have these physicists themselves been trained in philosophy?
They might have, but not as of, not as...
...not very much. Have they taken philosophy classes?
Probably. Yes.
I, I actually, maybe in intro philosophy classes, undergrads, but I'm willing to bet most of them have not taken a philosophy of science course.
Probably most, but some have. Sure.
So, there's a difference between like stepping back and thinking, which everybody should do if they're good practitioners of their, but there's just different ways of viewing the world that again, I do have training in science, and good philosophers of science will have some engagement with the science itself and the people who are practicing it. Now, and when we have conversation, it's interesting.
It's interesting and we learn things. It is a dialectic.
Mhm.
So it may be impossible for those fields to merge again, and maybe that's not the endgame, but to have a conversation is very fruitful because I change the way I think about how physics is being done right now. I learn about what they consider the interesting questions, how much progress we've made. It is all very interesting.
So why is this? So then we should, we should promote more of that. I, I've been like four or five different academic institutions, and at no time is the philosophy department having lunch with the chemist, the physicist, the biologist.
The problem...
...that's what she's saying. That's the problem.
You know.
And then when we do talk to each other, I think yes, you're going to find people like they don't have anything to do with each other. And you're going to find philosophers of science who are saying a bunch of stuff that has no connection to real science at all. And it could still be interesting. But if you're doing philosophy of physics in a way where you're trying to engage, you have to actually engage.
Maybe what I'm observing is the empirical fact that...
...this doesn't happen.
Yeah.
The philosophy departments don't have lunch with the physicists.
We should.
And so I'm, I'm observing that reality and commenting on it.
Yeah.
So that's all it is.
Cuz I, I long for the day...
...now that you have observed it, that reality is now entangled. For [laughter] so now it has to happen.
Actually, it's the observing that would destroy the intent.
Oh, that's right. They can't do it anymore. Sorry. The comedic inversion of that. At least, let me get you, uh, take us out with Einstein's comment on philosophy. Do you remember it?
Okay. He probably had several. I got.
Which one are you hoping for? The history and philosophy.
No, no, it's not that deep. This was very, this was very off the cuff of him. Sometimes when I think about philosophy, I feel like I'm chewing on something that's not in my mouth. [laughter]
Where's my book? Hand me my book. I want to read the quote. One quote from Einstein. That's a legit.
Okay, thanks for reminding me that the Einstein paradox. There's an academic.
It's an academic text.
Academic text.
It does presume some, um, acquaintance with quantum physics. Um, but [laughter]
Just, you know, a scooch quantum.
The Einstein paradox. The debate of non-locality and incompleteness in 1935.
The originator thesis.
Type. This is very, that's like a title of a thesis right there.
This is intricate work. It is intense work. So this is Einstein writing in June to Schrodinger, um, trying to figure out what on earth quantum mechanics means. Dear Schrodinger,
I was very pleased about your detailed letter dealing with our little paper. The actual difficulty lies in the fact that physics is a kind of metaphysics. Physics describes reality. He puts the scare quotes in. But we do not know what reality is. We know it only through our physical description. They are wedded together.
Wow.
Inseparable.
That's pretty cool. You call you calling notwin.
Didn't I say dear Irwin?
No, you said dear.
Dear. No. No. Just like buddies. Like if you're playing a sport, you don't say, "Hello there, Terrence."
[laughter]
I have in fact played sports in my life, despite what that sounded like.
Okay. [laughter] There it is. We got to wrap this. Well, thanks for this, this second visit to my office here at the Hayden Planetarium.
It's great stuff.
It's good to be back with you guys.
Yeah, this has been another installment of Star Talk.
Let's call it the physics of philosophy edition. [groaning]
Chuck,
Always a pleasure.
Uh, you are, uh, lord of comedy.
Ye. Yes. Kneel before me. [laughter]
Until next time, I'm Neil deGrasse Tyson. Keep looking up. [music] [music] [music]
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