The Limits of Knowing with Elise Crull

How do you know what you know? Neil deGrasse Tyson and comedian Chuck Nice explore issues with quantum mechanics and objectivity, the history of physics, and how scientists ask questions on the edge of our understanding with philosopher of physics Elise Crull.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  Chuck, we got some more philosophy in the house.

• 0:02Chuck Nice?

  Yes, along with physics.

• 0:04Neil deGrasse Tyson?

  Yes.

• 0:05Chuck Nice?

  Yeah.

• 0:06Neil deGrasse Tyson?

  And they, they.

• 0:07Chuck Nice?

  They're the richest pieces of science. They belong together.

• 0:11Neil deGrasse Tyson?

  Maybe physics and philosophy are entangled.

• 0:16Chuck Nice?

  Ooh.

• 0:18Neil deGrasse Tyson?

  More on that coming up.

• 0:22Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:35Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson, you're a personal astrophysicist. Got with me Chuck Knight, baby.

• 0:41Chuck Nice?

  Hey, hey, hey.

• 0:42Neil deGrasse Tyson?

  And Lord of Comedy.

• 0:44Chuck Nice?

  You know, that sounds so.

• 0:45Neil deGrasse Tyson?

  It does sound.

• 0:46Chuck Nice?

  Like pretentious.

• 0:47Neil deGrasse Tyson?

  But people call you Lord Nice, and so why not run it, run its course?

• 0:51Chuck Nice?

  Yeah, I am the, because it sounds like I should say, I am the Lord of Comedy.

• 0:56Chuck Nice?

  Like when people are like, Lord Nice, that sounds kind of cool. You know what I mean? It sounds like, like, you know, a term of endearment, more so than a title, the way they say it.

• 1:04Neil deGrasse Tyson?

  I got you, I got you.

• 1:04Chuck Nice?

  But when I say it, it's just like, bow down before me.

• 1:08Neil deGrasse Tyson?

  Bend the knee.

• 1:09Chuck Nice?

  Exactly. Will you bend the knee before the Lord of Comedy? Laugh not, I say, but capitulate.

• 1:18Neil deGrasse Tyson?

  We're revisiting the philosophy of physics.

• 1:21Chuck Nice?

  Oh, right.

• 1:22Neil deGrasse Tyson?

  Oh, right.

• 1:23Chuck Nice?

  Couldn't get enough the first time.

• 1:24Neil deGrasse Tyson?

  It triggered a lot of interest.

• 1:26Chuck Nice?

  Okay.

• 1:26Neil deGrasse Tyson?

  More than I expected or anticipated. And so.

• 1:30Chuck Nice?

  A lot of people like philosophy.

• 1:31Neil deGrasse Tyson?

  I think so.

• 1:32Chuck Nice?

  Did you bullshit today?

• 1:35Chuck Nice?

  Are you planning on bullshitting?

• 1:39Neil deGrasse Tyson?

  Well, we have an authentic philosopher in the house, once again, Elise Crull. Elise, welcome back to StarTalk.

• 1:46Speaker 02

  Hey, everybody.

• 1:48Neil deGrasse Tyson?

  Have you bullshitted today yet?

• 1:51Speaker 02

  Yes, but not about philosophy.

• 1:53Neil deGrasse Tyson?

  All right, all right, good answer. So let's remind people. Good answer. So you're Associate Professor of Philosophy at CUNY, City University of New York, City College. My father was an administrator there many moons ago. And your background is entirely in physics and philosophy. And I think there's some math in there, too. Is that right? Was there?

• 2:13Speaker 02

  There's some history.

• 2:14Neil deGrasse Tyson?

  Oh, history.

• 2:15Speaker 02

  I was one class away from getting a minor in math. And I decided to take tap dance instead and no looking back, man.

• 2:21Neil deGrasse Tyson?

  No, right, right. You gotta move that body, move that body. And so I love this. And you have a specialty in the history of quantum physics?

• 2:32Speaker 02

  The history and philosophy of quantum physics.

• 2:34Neil deGrasse Tyson?

  Yeah, because there's a lot of room to philosophize there. Let me tell you.

• 2:38Speaker 02

  Yes.

• 2:38Neil deGrasse Tyson?

  Because, you know, I'm happy to just calculate. But somebody's thinking about why. And I'm glad that's not me. Somebody else is doing that. And so part of why we have you back on, I'm reminded by not only my producers, but the comment thread that I might have been, or was certainly over exuberant in my conversation with you. Way beyond what is normal. Maybe I had like a lot of thoughts and feelings and, and, but you're the guest. That's hard to believe. No, no. Hard to believe that I.

• 3:17Speaker 02

  Look, I'm going to choose to understand it as, I mean, you guys have a great rapport. And what I do is intrinsically interesting.

• 3:24Neil deGrasse Tyson?

  So we're all in it.

• 3:26Speaker 02

  We're in it.

• 3:26Neil deGrasse Tyson?

  Well, I was totally in it, but I want to make sure because I'm an educator first.

• 3:30Speaker 02

  Yeah.

• 3:31Neil deGrasse Tyson?

  And I want to make sure that people come into this conversation more thoroughly informed and so that they can become enlightened.

• 3:42Speaker 02

  I appreciate that, Neil. Thanks.

• 3:44Neil deGrasse Tyson?

  So let's just, at the risk of sounding too pedantic, tell us. What philosophy is? Let me be more precise.

• 3:53Speaker 02

  Okay.

• 3:53Neil deGrasse Tyson?

  What is philosophy today compared with maybe 100 years ago, 200, 300 years ago? Back to Aristotle and the famous sort of Greek philosophers?

• 4:06Speaker 02

  Right, so I hope I won't be repeating like the same stuff.

• 4:09Neil deGrasse Tyson?

  Yeah, who cares?

• 4:10Speaker 02

  I only have like three jokes and I think I did two of them last time.

• 4:12Neil deGrasse Tyson?

  We got other jokes coming here, but we're good, we're good.

• 4:14Speaker 02

  Fresh, but that's maybe actually to the point. 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. But one of my favorite definitions of philosophy comes from philosopher of science Bas van Frazen.

• 4:30Neil deGrasse Tyson?

  That's a name?

• 4:32Speaker 02

  Van Frazen, yeah.

• 4:34Chuck Nice?

  Bas van Frazen, it sounds like a Haagen Dazs ice cream.

• 4:37Speaker 02

  Well, you know what, Haagen, yeah. They made that up. The Oomla's on the road, like they're like, let us sound European to sell our pecan ice cream.

• 4:45Neil deGrasse Tyson?

  And another made in Jersey. Haagen Dazs is made in Jersey.

• 4:47Speaker 02

  But Van Frazen is legit Dutch, which is like part of my heritage, right? But he says that philosophy, it might be asking similar questions, but every time you ask it, you're in a new context. New scientific context, new cultural context, new political context. And you're a different person asking it. And so there's a way that every time it's done, it's done anew.

• 5:11Neil deGrasse Tyson?

  And you could be a different person from yourself, having asked the question even just a year or two earlier.

• 5:16Speaker 02

  I think one thing, we tend to look really hard for coherent thought across a person's lifetime. But why should we expect that?

• 5:23Neil deGrasse Tyson?

  Well, we shouldn't.

• 5:25Speaker 02

  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's a bit of humility there. So, yeah, people, Aristotle defined metaphysics right after his book Physics. And for him, there were similar things. They're asking about what kinds of things we encounter in the world? 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 phenomena, like physical phenomena, right? Understanding their relationships and their behavior and their patterns and all this stuff. So they started together as the professions became a bit more. Specified.

• 6:10Neil deGrasse Tyson?

  Specialized.

• 6:11Speaker 02

  Specialized, yeah, thank you, that's the word. They teased apart a little bit, but even into the early 1900s, you have all these really famous philosophers like Ernst Mach and Einstein and Pierre Duhem and Poincaré and Lorenz.

• 6:25Neil deGrasse Tyson?

  Mach I, Mach II.

• 6:28Speaker 02

  Peter Sound.

• 6:29Neil deGrasse Tyson?

  Peter Sound in a medium, yeah. That same Mach.

• 6:32Speaker 02

  That same Mach. They were philosopher physicists.

• 6:36Neil deGrasse Tyson?

  Go before them, tell me, coming through Newton and Hook, because they didn't call themselves physicists, they were natural philosophers. So take me through that era before you land in the 1800s.

• 6:47Speaker 02

  Yeah, so again, Newton is building on Descartes. And Descartes was sort of the worldview that was building on Galileo and Kepler and Copernicus, 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 magnum opus, his great work, is called The Principles of Philosophy. And Newton is criticizing that particular book when he writes the principles, the mathematical principles of natural philosophy. Wait, did I get the title right? I only just called it The Principia, so I'd forgotten by then.

• 7:19Neil deGrasse Tyson?

  Yeah, so what you're saying is Newton's famous work post-dates Descartes' famous work. And he's, is he poking fun at the title and making it more of a product?

• 7:34Speaker 02

  He's trying to replace it.

• 7:35Neil deGrasse Tyson?

  Replace it.

• 7:36Speaker 02

  Right, this is what they, build on it.

• 7:38Neil deGrasse Tyson?

  Yeah, so let me get the right title. So Principia Mathematica Naturalis. So in English, the Mathematical Principles of Natural Philosophy. That's the full title.

• 7:49Speaker 02

  In Principles of Philosophy, there's four books. Descartes, 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?

• 8:13Neil deGrasse Tyson?

  Which is, which book has the "I think, therefore I am"?

• 8:16Speaker 02

  That is in the Meditations, which was published a few years before.

• 8:19Neil deGrasse Tyson?

  Oh.

• 8:19Speaker 02

  In forty-one.

• 8:20Neil deGrasse Tyson?

  So he was already trying to go there.

• 8:21Speaker 02

  So book one of the Principles is like a polished version of the Meditations.

• 8:26Neil deGrasse Tyson?

  Alright.

• 8:26Speaker 02

  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 arguably, Poincaré argues are not helpful, and there's a way that that's true. And then there's the General Scolium, 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 derives the three laws of motion.

• 9:02Neil deGrasse Tyson?

  And gravity would come in there.

• 9:03Speaker 02

  And gravity is even later down the line.

• 9:04Neil deGrasse Tyson?

  Right, right.

• 9:05Speaker 02

  But the first thing that they considered having to do was talking about how we know what we...

• 9:11Neil deGrasse Tyson?

  How do you know what you know? Okay, so...

• 9:12Speaker 02

  And then do you know that you know what you know? And is it important to know whether you know if you know if you know? Or like... I don't know.

• 9:18Neil deGrasse Tyson?

  I would say...

• 9:21Speaker 02

  Which is right.

• 9:22Neil deGrasse Tyson?

  Did he give the right answer to that?

• 9:24Speaker 02

  Sure, yeah.

• 9:25Neil deGrasse Tyson?

  Okay. So through that period, the various folks who were trying to do physics are fundamentally conjoined with philosophical foundations of why they're thinking that way at all.

• 9:36Speaker 02

  Right.

• 9:36Neil deGrasse Tyson?

  Okay, so now, fast forward, or slow forward, into the seventeen hundreds, now take us to the eighteen hundreds.

• 9:43Speaker 02

  Scientific revolution time, also actual revolution time for a variety of countries. Also...

• 9:50Neil deGrasse Tyson?

  Merca.

• 9:51Speaker 02

  Yeah. Merca?

• 9:53Neil deGrasse Tyson?

  Merca. Merca and, and of course France.

• 9:55Speaker 02

  France. Liberté, fraternité.

• 9:58Neil deGrasse Tyson?

  Liberté, that's right.

• 10:00Speaker 02

  Tobacco.

• 10:01Neil deGrasse Tyson?

  Oh yes.

• 10:02Speaker 02

  Wait, I don't know, wait. I don't know how to say tobacco in French, which is probably a good thing.

• 10:09Chuck Nice?

  Keep your stinking freedom fries.

• 10:14Speaker 02

  Because we didn't like the idea of a monarchy. That's our history, rebelling against a monarchy. Anyway.

• 10:21Neil deGrasse Tyson?

  I see what you did there.

• 10:24Speaker 02

  They're writing to each other and corresponding and setting up experiments. Boyle, Gesundie, Newton, Leibniz, the people who were still philosopher physicists in the 1700s and 1800s. They're also now working with Newton's Principia. And it's known pretty early on that the Principia doesn't answer everything. Like the law of gravity is action at a distance. Because it just says if, I mean, imagine a universe with nothing in it. If two masses just popped into existence, they would somehow immediately feel the force between the two. Right?

• 10:58Neil deGrasse Tyson?

  Okay.

• 10:59Speaker 02

  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. No, it's instantaneous. So people knew there were issues. And one of the main people was Emily de Chatelet, who wrote a book called The Foundations of Physics. Right, so before, you know, maybe.

• 11:18Neil deGrasse Tyson?

  When was that? I'm gonna, I'm gonna pick that up.

• 11:20Speaker 02

  She's in the mid 1700s.

• 11:21Neil deGrasse Tyson?

  Thank you for that.

• 11:22Speaker 02

  And she's experiencing a Renaissance right now. For a long time, she was just known as like Voltaire's lover and mistress, and she hosted many salon.

• 11:37Neil deGrasse Tyson?

  Salon.

• 11:40Speaker 02

  I don't know, I don't know how to say French things.

• 11:43Neil deGrasse Tyson?

  Just I wanted to make sure the timeline is established here. So Newton's greatest work was done in the 1600s.

• 11:49Speaker 02

  1687.

• 11:50Neil deGrasse Tyson?

  Spilling into.

• 11:51Speaker 02

  Early 1700s.

• 11:51Neil deGrasse Tyson?

  Early 1700s. Voltaire comes around mid 1700s.

• 11:55Speaker 02

  A little earlier, yeah.

• 11:56Neil deGrasse Tyson?

  A little earlier.

• 11:56Speaker 02

  I think.

• 11:56Neil deGrasse Tyson?

  And so, and you're.

• 11:58Speaker 02

  And de Chatelet is the same time.

• 11:59Neil deGrasse Tyson?

  De Chatelet. And so they're, they're coincident in time.

• 12:02Speaker 02

  That's right.

• 12:02Neil deGrasse Tyson?

  Yes.

• 12:03Speaker 02

  And she is, so she's hosting a lot of the intellectuals of the time and like they're having interesting conversation. But she's also in charge of teaching her kid, her, her son, 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.

• 12:19Neil deGrasse Tyson?

  As one does.

• 12:20Speaker 02

  As one does.

• 12:21Neil deGrasse Tyson?

  You did that with your kids too.

• 12:22Chuck Nice?

  See all the textbooks my kids are reading. They're all wrong because I wrote it.

• 12:28Speaker 02

  Do you put as like the byline is like. Lord of comedy, comma, 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 reason.

• 12:49Neil deGrasse Tyson?

  Wait, law of, do they declaring that it's a law?

• 12:53Speaker 02

  It's an axiom.

• 12:54Neil deGrasse Tyson?

  Okay.

• 12:54Speaker 02

  You have to start somewhere, so.

• 12:55Neil deGrasse Tyson?

  Okay, so you're laying out some rules.

• 12:56Speaker 02

  That's right.

• 12:57Neil deGrasse Tyson?

  Rules and regulations.

• 12:58Speaker 02

  Yeah, you gotta bite the bullet somewhere.

• 12:59Neil deGrasse Tyson?

  And what follows derives within those constraints.

• 13:03Speaker 02

  Yes.

• 13:04Neil deGrasse Tyson?

  Okay, gotcha.

• 13:04Speaker 02

  So, but she's also the one who translated the principia 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.

• 13:22Neil deGrasse Tyson?

  Wow.

• 13:22Speaker 02

  And so it's her physics that is trained.

• 13:24Neil deGrasse Tyson?

  That's badass. Pull out Newton, say, Newton, you need help. Here's what you left out, Newton.

• 13:28Speaker 02

  Exactly. And so it was, people kinda 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.

• 13:39Neil deGrasse Tyson?

  And how many lady physicists existed at the time?

• 13:44Speaker 02

  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.

• 13:58Neil deGrasse Tyson?

  Wow.

• 13:59Speaker 02

  Corresponding with Leibniz, corresponding with Hume, um, interacting, like writing, influencing Leibniz's thought.

• 14:06Neil deGrasse Tyson?

  Interesting, because I have a book which is Leibniz's letters.

• 14:09Speaker 02

  Yeah.

• 14:10Neil deGrasse Tyson?

  And, and there's all manner of people that are on the other side of those letters. I'll take another look at them.

• 14:15Speaker 02

  Yeah.

• 14:15Neil deGrasse Tyson?

  Why we all know Leibniz today. Just tell Chuck.

• 14:18Speaker 02

  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 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.

• 14:36Neil deGrasse Tyson?

  Okay.

• 14:37Speaker 02

  A relational view. And so he objected to the idea. Idea, 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.

• 14:54Chuck Nice?

  Space is part of it.

• 14:55Speaker 02

  But for Leibniz, it just is how we understand the difference between the the distance between matter.

• 15:02Chuck Nice?

  I'm confused here. There are two independent calculus and they both work?

• 15:08Speaker 02

  They they

• 15:10Neil deGrasse Tyson?

  You know, they're different because all the notation is different. And in physics, we retain a lot of Newton's notations.

• 15:16Chuck Nice?

  Okay.

• 15:17Neil deGrasse Tyson?

  But in pure math, it's all Leibniz's. You know, the integral signs and all these

• 15:22Speaker 02

  That's Leibniz, right?

• 15:22Neil deGrasse Tyson?

  It's Leibniz. Yeah, it's all Leibniz. And so Leibniz is a little more elegant than Newton's. Newton was like, let's get in and get the job done and get out kind of thing.

• 15:30Chuck Nice?

  All right.

• 15:31Neil deGrasse Tyson?

  But I'm impressed that that it would happen at this basically at the same time and independently.

• 15:36Speaker 02

  I love calculus. I don't know why people give it such a bad rap.

• 15:38Chuck Nice?

  I didn't know you. That's the thing I never thought I'd hear this morning.

• 15:43Chuck Nice?

  I love calculus. When I woke up this morning, that's what I thought I'd never hear.

• 15:48Neil deGrasse Tyson?

  Is that a bumper sticker on your car?

• 15:50Chuck Nice?

  I love calculus.

• 15:51Speaker 02

  I don't have a car, but if I did, that would be one of them for sure.

• 15:53Neil deGrasse Tyson?

  All right.

• 16:08Speaker 03

  I'm Nicholas Costella and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 16:26Neil deGrasse Tyson?

  So now we got them. Now take us now into the 19th century.

• 16:28Speaker 02

  As technology gets better, we get we're

• 16:31Neil deGrasse Tyson?

  The industrial revolution.

• 16:32Speaker 02

  Yes. And all these like, we start moving from talking about forces and inertia and stuff where they can't fully analyze. 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.

• 17:03Speaker 02

  Professional societies like the Royal Society and the Paris Society of Scientists are growing. So now you have communities growing up where people share their findings and it's international, at least in the West, and so on. It's a long and interesting story, which other people could probably give a better version of, but it's this increasing ability to quantize 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."

• 17:39Chuck Nice?

  Yeah.

• 17:40Speaker 02

  This is not possible anymore.

• 17:41Neil deGrasse Tyson?

  I think at least, I think that was true up until much later than that.

• 17:45Speaker 02

  Really?

• 17:46Neil deGrasse Tyson?

  Like, rumor has it, I've heard told, that up through the 1500s, highly educated people could have claimed to have read everything that was ever written.

• 17:55Speaker 02

  Yeah.

• 17:56Chuck Nice?

  Well, that's because it was all handwritten.

• 17:58Neil deGrasse Tyson?

  Real slow.

• 17:59Speaker 02

  Yeah, but some people like Aquinas, they had scribes. They had like a room full of monks writing for them.

• 18:04Chuck Nice?

  Just writing on their sheets. As they go into these communities, when does all of this lead to what we are? Because none of this stuff is cross-pollinating today.

• 18:14Speaker 02

  Well, I wouldn't say none of it is. I would say it's harder to do.

• 18:17Chuck Nice?

  Okay.

• 18:17Speaker 02

  And I'd say people are still asking these questions. But we've built, and we 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.

• 18:30Chuck Nice?

  Okay.

• 18:31Speaker 02

  Liberal arts training is being kicked like a poor little puppy. And it's like such an important thing.

• 18:38Chuck Nice?

  Right.

• 18:39Speaker 02

  And then when you get to graduate school, it's all over. It used to be like you would try to stay general, even through your master's degree, you would take a little bit of, like, you would learn everything.

• 18:46Neil deGrasse Tyson?

  Are you saying it's important because it just kept you loose?

• 18:49Speaker 02

  Yeah. It kept you learning a bunch of other stuff.

• 18:51Neil deGrasse Tyson?

  Other stuff.

• 18:51Speaker 02

  And appreciating...

• 18:52Neil deGrasse Tyson?

  The dimensions of life and of society.

• 18:55Speaker 02

  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 Physicist by Daniel Kevlus. It might be a little outdated by now, but it just talks about the history of physics in the US and how it became...

• 19:10Speaker 02

  So many different specializations and so on. But it was only after the Manhattan Project and after World War II that physics was properly considered a thing you could have as a career. It wasn't just something you learned as a young man at the university, or one of the few women, but it was something you could have, you could bring home the bacon, right? If you actually did physics or engineering.

• 19:31Neil deGrasse Tyson?

  But at that point, physics is making bombs.

• 19:32Speaker 02

  That's right.

• 19:33Neil deGrasse Tyson?

  They're important for national security, and no one is talking about philosophy at that point.

• 19:38Speaker 02

  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 its competition. But interestingly, in the 50s and 60s, James Conant, who was the president of Harvard and a physicist and a chemist.

• 19:55Neil deGrasse Tyson?

  I didn't remember that about that.

• 19:56Speaker 02

  Conant fought really hard for even his physics students to know the history and philosophy. He understood it is 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.

• 20:16Neil deGrasse Tyson?

  You're saying explicitly and implicitly that coming out of the 19th century into the 20th, especially post-war, the field of physics has borders, in a way.

• 20:30Speaker 02

  Yeah.

• 20:31Neil deGrasse Tyson?

  Where other ways of thinking can't get in.

• 20:33Speaker 02

  Yeah.

• 20:34Neil deGrasse Tyson?

  And you're saying that's to the detriment of physics, not to the detriment of other fields? How would you characterize that?

• 20:41Speaker 02

  I think it's to the detriment of any field, not just science, when those walls became impermeable. I think walls are very good.

• 20:49Neil deGrasse Tyson?

  Stop. Physics, as far as I can tell today, still suffers from this border problem.

• 20:57Speaker 02

  It makes sense, because we're on, we get hyper-specialized, because we know so much and 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.

• 21:12Neil deGrasse Tyson?

  So how do we use you?

• 21:13Speaker 02

  Well, maybe I don't want to be used.

• 21:16Neil deGrasse Tyson?

  Okay, okay, sorry.

• 21:17Speaker 02

  Maybe I get to be exist in my own right, because it's a beautiful and wonderful human endeavor.

• 21:22Neil deGrasse Tyson?

  It came out wrong.

• 21:23Speaker 02

  No, I know what you mean.

• 21:24Neil deGrasse Tyson?

  How do you help us?

• 21:25Speaker 02

  Okay, we help each other when we share ideas, when we...

• 21:30Speaker 02

  Have conversations like we're doing now. So, for instance, I was just talking about Mach. He was an important influence on 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, at a more intimate level in physics, like that choosing something that's parsimonious, or beautiful, or simple, or whatever. There's no reason why the Earth should, or why nature should, give a damn about those principles.

• 22:14Neil deGrasse Tyson?

  About our aesthetics.

• 22:17Speaker 02

  Yeah.

• 22:17Neil deGrasse Tyson?

  Right.

• 22:17Speaker 02

  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. So there are moments, you have to sort of buy into certain untestable principles to consider science worth doing. But the thing is, these are important things, but the concepts that we use too. So here's a good point. 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, was an important question to ask. But Mach, and Einstein, and others, at the end of the 19th century, are clear that electrodynamics isn't gonna work in absolute space and time.

• 23:01Speaker 02

  Like, 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 gonna be to push around the equations, but to reevaluate the basic concepts.

• 23:13Neil deGrasse Tyson?

  And just to be fair to Newton, the whole, electrodynamics, the physics that came to be understood, that we call electrodynamics, was not yet there for Newton.

• 23:25Speaker 02

  Yeah.

• 23:26Neil deGrasse Tyson?

  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.

• 23:33Speaker 02

  Yeah.

• 23:33Neil deGrasse Tyson?

  Right?

• 23:34Speaker 02

  So, you know... Late 19th century, there's tension between these pillars of physics, like thermodynamics, system mechanics, and I'm blanking, sorry. Newtonian mechanics, sorry, classical mechanics. 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 different frames of reference?"

• 24:10Neil deGrasse Tyson?

  These are not questions physicists typically ask.

• 24:13Speaker 02

  Well, they were for the heroes of Einstein. And the class of people who were philosopher-physicists was a significant class of people

• 24:23Neil deGrasse Tyson?

  At the time.

• 24:23Speaker 02

  A century ago.

• 24:24Neil deGrasse Tyson?

  Yeah.

• 24:24Speaker 02

  That's right. So that it wasn't for the last 50, 70-some years is partly because of, like, there are political reasons for it, like the intellectuals who came to the US from Germany during the wars, 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 end point is that, if we take Einstein's word for it, this going back and saying, "Are we really understanding this concept

• 25:09Speaker 02

  the way we should be?" And this is what we're doing right now with gravity and trying to understand the quantize 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? 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? Who do we fund? Where do we send our best graduate students?

• 25:52Speaker 02

  That is based on who has the framework that you find the most... compelling whose view about the nature of space and time, how general relativity and quantum mechanics fit together.

• 26:03Neil deGrasse Tyson?

  So Brian Greene's bestselling book, The Elegant Universe.

• 26:06Speaker 02

  Yeah.

• 26:07Neil deGrasse Tyson?

  Just in all fairness to him, that was not his original title.

• 26:09Speaker 02

  What was it?

• 26:10Neil deGrasse Tyson?

  It was some more boring title. The publisher chose that and that had a certain cachet with the public.

• 26:16Chuck Nice?

  Yeah, well.

• 26:17Neil deGrasse Tyson?

  And, and, but it implies that we as scientists are in search of beauty, majesty and elegance in the universe, as though it's waiting for us to discover it.

• 26:27Chuck Nice?

  It's like the universe is going to a cocktail party, darling.

• 26:30Neil deGrasse Tyson?

  Presumably that's still okay to look to have some prior expectation for the universe to guide your next questions.

• 26:40Speaker 02

  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 gonna be there, but elevating those guidelines to the level of dogma is when we get in trouble.

• 26:54Neil deGrasse Tyson?

  Cause then it affects who you hire into departments.

• 26:56Speaker 02

  Yeah, but it also affects what you consider the correct route to go.

• 27:01Chuck Nice?

  It, it shapes your whole outlook on how you're gonna approach everything.

• 27:05Speaker 02

  Right.

• 27:06Chuck Nice?

  You know, cause you're like, well, can't do that because we've already made up in our mind that this is the way it's gotta go.

• 27:12Speaker 02

  Right, or I mean, you, you have to bet on a pony, right? I mean, if you're choosing whether you're gonna pursue like canonical approaches to quantum gravity, like loop quantum gravity versus covariant, like gauge theoretic, like string theory, like what Brian Greene does.

• 27:24Chuck Nice?

  What is she saying, please?

• 27:25Neil deGrasse Tyson?

  I'm pretending.

• 27:26Chuck Nice?

  I don't have any idea what you are talking about right now.

• 27:29Neil deGrasse Tyson?

  Different approaches to solving a problem that we know exists.

• 27:32Speaker 02

  There, there are like two base, 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.

• 27:42Chuck Nice?

  Okay, that's so far with you.

• 27:44Speaker 02

  And one of the approaches is trying to build a theory of everything from the ground up. String theory is kinda like that.

• 27:48Chuck Nice?

  Heard that, go ahead.

• 27:49Speaker 02

  Okay. Uh, the canonical approaches say, we think quantum theory is, is the most fundamental theory, so we're gonna try and bring GR into that framework.

• 27:59Chuck Nice?

  Gotcha.

• 28:00Speaker 02

  But that is something we, that is something we can never empirically prove which is the right path to pursue.

• 28:05Neil deGrasse Tyson?

  Look, I tell you why I, I'm leaning that way.

• 28:07Speaker 02

  Yeah.

• 28:08Neil deGrasse Tyson?

  Because no one has ever found a

• 28:13Neil deGrasse Tyson?

  Quantum physics prediction that was false. 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.

• 28:33Speaker 02

  If you can't calculate, you know, stuff about black holes, get out.

• 28:36Neil deGrasse Tyson?

  No, no, no, no, what I'm saying is.

• 28:39Speaker 02

  Not people, I'm not talking about people, I'm talking about abstract entities.

• 28:44Neil deGrasse Tyson?

  What I'm saying is, if you already know, if you already know the limits of general relativity.

• 28:50Chuck Nice?

  Right.

• 28:51Neil deGrasse Tyson?

  And you don't know the limits of quantum physics because you've never seen the limit.

• 28:55Chuck Nice?

  So you.

• 28:56Neil deGrasse Tyson?

  I'm thinking quantum is more badass.

• 28:58Chuck Nice?

  That probably goes in here, not the other way around.

• 29:01Neil deGrasse Tyson?

  Or, or of course, there could be a third entity.

• 29:04Speaker 02

  There could be a whole other batch. 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. 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. This idea that you, you ask the person on the street, what are, 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. 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.

• 29:48Speaker 02

  Like, how would you know as one single person even that, that this is a special kind of truth? Now, it's true that we have.

• 29:57Neil deGrasse Tyson?

  How true is it?

• 29:58Speaker 02

  Empirical. Medium capital T. Like the slash is somewhere between.

• 30:04Neil deGrasse Tyson?

  Okay.

• 30:05Speaker 02

  Quasi.

• 30:06Neil deGrasse Tyson?

  Different sized Ts to begin the word truth.

• 30:08Speaker 02

  I'm gonna say like, you know, 50, 50, I don't know, like 20 proof. That is weak sauce. Anyway.

• 30:16Speaker 02

  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. 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 prod it and study it and ask lots of questions, blow it with hot air, like see what comes out. And that's how you do, like, you have to assume that there's some divide between your apparatuses that are measuring the thing and the thing itself. This is a very old problem. I think it's even Aristotle's-

• 30:52Neil deGrasse Tyson?

  It's a measurement problem.

• 30:53Speaker 02

  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've-

• 31:10Chuck Nice?

  He can't fly around anymore.

• 31:11Speaker 02

  Well, you don't want that happening, right?

• 31:13Neil deGrasse Tyson?

  Yeah, I thought that was Feynman had a whole lecture on birds.

• 31:16Speaker 02

  Oh, then I really don't want to quote Feynman for a lot of reasons.

• 31:20Neil deGrasse Tyson?

  But I like what you said, where if you really want to know what a bird is, you have to open it up, cut it open, and then it's not the bird that you were studying.

• 31:30Speaker 02

  Right.

• 31:31Neil deGrasse Tyson?

  You just influenced the thing you were trying to understand.

• 31:33Speaker 02

  So, we know how to sort of quotient out that engagement in classical theories to a point that we can get very nice predictions of, like, football trajectories and-

• 31:44Neil deGrasse Tyson?

  Hence the idea of an objective truth.

• 31:47Speaker 02

  Right. But what happens in quantum mechanics is, and Bohr and many others were realizing this already in 100 years ago, right in 1925, when it was first developed, that there's-

• 31:57Neil deGrasse Tyson?

  100 years ago? We're in the centennial?

• 32:00Speaker 02

  That's right. It is the 100th anniversary of-

• 32:03Neil deGrasse Tyson?

  We did a whole live show at Beacon Theater, celebrating the centennial.

• 32:07Speaker 02

  There's been a lot of celebrations. It's the International Year of Quantum. I'm just gonna have, like, I'm gonna have to sleep for all of 2026. But that's when wave mechanics was developed and new physics-

• 32:16Neil deGrasse Tyson?

  Yeah, every year. And Hubble discovers that we're not the only galaxy.

• 32:21Speaker 02

  Wow.

• 32:22Neil deGrasse Tyson?

  1826.

• 32:23Speaker 02

  There's always something to celebrate, right?

• 32:24Neil deGrasse Tyson?

  1926, right.

• 32:25Speaker 02

  There's a way, when you're talking about quantum systems, like photons and electrons and these things, that you cannot avoid interacting with a system in a way that cannot be- Quotient to doubt. And so, this is something that Einstein continued to look for. In particular, he thought that when you're, when a physical theory is complete, that means that you can give a mathematical state bijectively. That means there's a mathematical state that corresponds to some real system in the world.

• 32:55Neil deGrasse Tyson?

  Did you just use the word bijectively?

• 32:57Speaker 02

  Yeah, sorry about it.

• 32:58Neil deGrasse Tyson?

  That's a word?

• 32:59Speaker 02

  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.

• 33:05Neil deGrasse Tyson?

  Interesting.

• 33:05Speaker 02

  That's all. That there's a nice correspondence.

• 33:08Neil deGrasse Tyson?

  Bijectively, cool.

• 33:10Speaker 02

  And I think somewhere else Schrodinger says, yeah, Einstein, he likes a map with a little flag on it saying, here's this system and here's the system, right? And because in, in Schrodinger's wave mechanics, you can't do that anymore. Because once a system, two subsystems have interacted quantum mechanically, and we pull them apart, and even after their interaction has ceased, Einstein says, you should, if you have a complete theory, you should be able to give a state, a description mathematically of this guy over here that doesn't make reference to this guy over here.

• 33:43Chuck Nice?

  Oh, that's...

• 33:45Speaker 02

  They're totally separable.

• 33:46Chuck Nice?

  That's kind of a, an issue, right?

• 33:48Speaker 02

  It is.

• 33:50Speaker 02

  It's his.

• 33:50Neil deGrasse Tyson?

  That's a little bit of an issue.

• 33:51Speaker 02

  Because entanglements can be understood as non-separability.

• 33:55Chuck Nice?

  Right.

• 33:56Speaker 02

  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...

• 34:05Neil deGrasse Tyson?

  It's a new thing.

• 34:06Speaker 02

  It's a new thing, and it's not just a new thing, it is, according to Schrodinger, the thing that causes departure between classical theories and quantum theories. When systems interact, something weirdly different happens, and you can no longer talk about the system, the physics of one.

• 34:21Chuck Nice?

  Without considering the other or referencing.

• 34:23Speaker 02

  That's right.

• 34:24Chuck Nice?

  Because, wow, that's wild.

• 34:26Speaker 02

  It is wild.

• 34:27Chuck Nice?

  I, I, I love it.

• 34:29Neil deGrasse Tyson?

  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. Just talk about the macroscopic classical physical world, right?

• 34:41Chuck Nice?

  Well, can you have both? I mean, can you just isolate the one for those circumstances? And then have the question of the other, like philosophically and I'll say physically? Is that possible?

• 34:56Speaker 02

  It is, but even Einstein realized right away that quantum theory, if it's about the really small stuff, what is the big stuff made of?

• 35:07Chuck Nice?

  Well, yes.

• 35:08Speaker 02

  A bunch of the really small stuff. So there's a way that Schrodinger's 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? And we can give really good physics explanations now for why that's the case. But a lot of people mistakenly think that the Copenhagen interpretation, like Bohr and the others, that were so intent on recovering objectivity, so we could talk about quantum

• 35:50Speaker 02

  science, 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...

• 36:00Neil deGrasse Tyson?

  It's a blunt instrument.

• 36:01Speaker 02

  It's a blunt instrument, that's right. And then you have the quantum system that it's interacting with. But in order for them to interact, we have to talk about them in the same theory.

• 36:11Neil deGrasse Tyson?

  However, aren't you allowed to say, macroscopic objects, all these wave equations average out, and to get to this classical result?

• 36:22Speaker 02

  But we know better than, it's not just averaging out, it's a process called quantum decoherence.

• 36:27Chuck Nice?

  Decoherence, sure.

• 36:28Speaker 02

  Entanglement, yeah, entanglement itself, when you, well, it's the same problem about objectivity, but, first of all, I just wanted to clear that, like, Bohr never, in his post-World War II popul lectures 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 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 machine with a pointer, 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

• 37:12Speaker 02

  divide between the object we're studying and the world around it that accounts for why we can't see things as quantum mechanical, it's because the things, the quantum systems we're looking at are in fact interacting with lots of other stuff.

• 37:47Neil deGrasse Tyson?

  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?

• 38:00Speaker 02

  It depends.

• 38:01Neil deGrasse Tyson?

  That's right, are they headed to a place, is that a goal at all?

• 38:04Speaker 02

  Well, if you mean objectivity as intersubjective 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 we want.

• 38:14Neil deGrasse Tyson?

  Okay, of course, because otherwise there's no science without that.

• 38:16Speaker 02

  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...

• 38:27Neil deGrasse Tyson?

  Where do you get all the scoop on people?

• 38:29Chuck Nice?

  And I'm gonna tell you some.

• 38:31Speaker 02

  I read their letters.

• 38:32Neil deGrasse Tyson?

  All the letters? Because not in their books, right.

• 38:35Chuck Nice?

  Let me just say this one thing, make a correction there, there is no such thing as a wee bit of cocaine.

• 38:40Speaker 02

  You can't do a quantum.

• 38:44Speaker 02

  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 physical, 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 onstage what non-locality meant about the world.

• 39:20Neil deGrasse Tyson?

  Okay, so tell us what non-locality means.

• 39:23Speaker 02

  I'm not going to be able to supply an answer if two Bell no Lord. I think, I think it's just indicating that systems are in... Quantum interaction is a kind of interaction we have never studied before.

• 39:36Neil deGrasse Tyson?

  Okay, so non-locality means these two particles that are entangled cannot be described independently

• 39:42Speaker 02

  That's right.

• 39:42Neil deGrasse Tyson?

  of each other. So, so this is not local. It is connected.

• 39:47Speaker 02

  So it's not just that, because we could do that classically, right? If Chuck always wore different color socks, and I saw just one of his socks on a given morning, it's 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. Exactly. Right? Okay. That's purely classical, not interesting. What makes it very non, uh, non-classical 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're, 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.

• 40:31Speaker 02

  Spin with respect to some angle or something.

• 40:34Neil deGrasse Tyson?

  Measuring a quantum property of that

• 40:36Speaker 02

  That's right.

• 40:37Neil deGrasse Tyson?

  entity.

• 40:37Speaker 02

  Yeah, some property of that entity. And the other one will know.

• 40:43Chuck Nice?

  What it is that was measured and what state the other thing is.

• 40:47Neil deGrasse Tyson?

  So therefore, it's not local.

• 40:48Chuck Nice?

  So, right.

• 40:49Speaker 02

  That is the non-locality. So it's not just that there's a correlation between the two. We have lots of classical correlations that we love. But it's that these correlations cannot be explained. They, the correlations exceed like just statistical randomness.

• 41:03Neil deGrasse Tyson?

  Can you one day?

• 41:05Speaker 02

  But yet, they can't be talking to each other.

• 41:07Neil deGrasse Tyson?

  Can you one day?

• 41:08Chuck Nice?

  That's what, there you go.

• 41:10Speaker 02

  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, I'm happy with the speed of light being what it is.

• 41:21Neil deGrasse Tyson?

  But at least, why not go, go full Monty here and say the two particles are connected via wormhole?

• 41:27Speaker 02

  So there are, we could give alternate explanations, but wormholes are way, they would have other effects, wouldn't like they would have other?

• 41:36Neil deGrasse Tyson?

  It's, it's a, it's an entanglement wormhole. I mean, who knows? With a wormhole, you're not moving faster than the speed of light. You're just cutting through the space-time continuum instantaneously.

• 41:46Speaker 02

  I think it would be hard because entanglement, non-locality is, is, is so ubiquitous. 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.

• 42:14Neil deGrasse Tyson?

  Okay. So now I measure one of the particles. The other one manifests itself with the complementary properties. And now I've just de, they're no longer coherent.

• 42:25Speaker 02

  Yeah, they're no longer entangled after you've done that measurement. Yeah, yeah.

• 42:28Neil deGrasse Tyson?

  Now they're local particles.

• 42:30Speaker 02

  Yeah. In fact, the measurement that you do, the physics that we're doing is all local over there. Right? But yet there's this thing we can't explain.

• 42:37Neil deGrasse Tyson?

  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?

• 42:53Speaker 02

  I think we could use all the help we can.

• 42:55Chuck Nice?

  Yeah.

• 42:56Speaker 02

  Let's all talk to one another.

• 42:57Chuck Nice?

  Who cares where it comes from? All hands on deck.

• 42:59Neil deGrasse Tyson?

  All hands on deck.

• 43:00Speaker 02

  I mean, so there's a.

• 43:01Chuck Nice?

  I'm sorry. Cause I'm still, you guys were moving very quick. And I'm the guy sitting here without any PhD of anything. Okay? So.

• 43:11Neil deGrasse Tyson?

  You don't have a PhD?

• 43:13Chuck Nice?

  Yeah.

• 43:14Speaker 02

  Somebody get this man an honorary doctorate.

• 43:16Neil deGrasse Tyson?

  Who invited you? Okay.

• 43:19Chuck Nice?

  So, based on what you just said, because I'm running it back in my head, is it the actual measurement at the time of measurement that makes the entanglement? Or if there, is there ever a decoupling at all? Or are they measured and then tangled and then forever entangled?

• 43:41Speaker 02

  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 ways you can gather some information, but not fully decouple it. 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 this is why we can use entanglement as a resource. It's like to help us explore different like topologies and in, in, in holography, which is, you know, ADS, like anti-disider space and how it relates to conformal field theories, which I don't really know about and I want to figure out, like, I gotta get a firm. But they're using entanglement as a way to probe unmeasurable stuff.

• 44:25Neil deGrasse Tyson?

  Okay, we gotta land this plane. So the way I want to land the plane is to get you.

• 44:29Chuck Nice?

  That's super cool, man. I'm telling you.

• 44:30Speaker 02

  It's very cool.

• 44:30Chuck Nice?

  I mean, unbelievable.

• 44:31Speaker 02

  Yeah.

• 44:32Neil deGrasse Tyson?

  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? With a pathways of understanding? That'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 you, but maybe God does.

• 45:09Chuck Nice?

  My answer's done!

• 45:11Neil deGrasse Tyson?

  Maybe God is a gambler and just deal with it.

• 45:14Speaker 02

  Yeah, people have a different. People have different questions about that. So here's another, like, if you're a physicist who does quantum theory, or you're an experimental quantum physicist, and you believe that 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.

• 45:36Neil deGrasse Tyson?

  Which you're being statistical.

• 45:37Speaker 02

  Yeah. 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...

• 46:00Neil deGrasse Tyson?

  We didn't evolve in a quantum state.

• 46:02Speaker 02

  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-toothed tiger. So it's good for us as a species.

• 46:16Neil deGrasse Tyson?

  You would be summarily removed from the gene pool.

• 46:18Speaker 02

  Yeah.

• 46:22Neil deGrasse Tyson?

  Yeah, I prefer a classical...

• 46:23Speaker 02

  It's a good thing for physicists.

• 46:25Neil deGrasse Tyson?

  A classical understanding of the saber-toothed tiger wins every time. Yes.

• 46:31Speaker 02

  If that's the only thing that the audience takes away, that's a good one. For those who live near saber-toothed tigers. They're extinct, right?

• 46:38Neil deGrasse Tyson?

  Yeah.

• 46:39Speaker 02

  Biology is not my area of expertise.

• 46:41Neil deGrasse Tyson?

  But I got news for you.

• 46:43Chuck Nice?

  The regular tigers, they'll eat you too.

• 46:46Speaker 02

  Let's stick with the regular tigers.

• 46:47Neil deGrasse Tyson?

  They're good enough.

• 46:48Speaker 02

  We have sharks and things, it's all good.

• 46:49Neil deGrasse Tyson?

  They'll eat you too. Plus, they're on the list for becoming de-extincted, the saber-toothed tiger.

• 46:55Speaker 02

  The fact that we can do that now, so cool. 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? 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? Are we testing our assumptions? Like, these conversations, while we're so wedded to the classical picture of things, that understanding-

• 47:33Neil deGrasse Tyson?

  It's not our fault. We evolved that way.

• 47:36Speaker 02

  Very natural, right? But it also means that we have to do a lot of work to continue unmooring ourself from that perspective.

• 47:43Neil deGrasse Tyson?

  Ooh, I like that phrase. Unmooring. So, so, okay, all hands on deck.

• 47:47Speaker 02

  Keep doing it.

• 47:48Chuck Nice?

  No, it makes sense. I mean, it's like, you're, really, it's kind of a, you know, an ossification that happens.

• 47:56Speaker 02

  That's another really good word.

• 47:57Chuck Nice?

  You know, because of the practice. The practice itself. And then what you have to do now is, 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.

• 48:13Speaker 02

  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, epistemology, social-political philosophy. These are important areas of philosophy that leave-

• 48:36Neil deGrasse Tyson?

  Ethical philosophy, religious philosophy, even economic philosophy.

• 48:40Speaker 02

  Philosophy of law.

• 48:41Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 48:41Speaker 02

  Philosophy of the emotions. Like, these things can stay pretty far-

• 48:44Neil deGrasse Tyson?

  Space law. That's another frontier, where they need some philosophers.

• 48:47Speaker 02

  I really, every time I-

• 48:48Neil deGrasse Tyson?

  Who owns the moon?

• 48:49Speaker 02

  Every time I, every time I meet a lawyer, I ask if they're a maritime lawyer, because they're gonna be the first ones who, like, develop, they're gonna be the ones- Yeah, a good friend of-

• 48:57Chuck Nice?

  Has your satellite crashed into another satellite?

• 48:59Neil deGrasse Tyson?

  That's not the cat-

• 49:01Speaker 02

  No, listen.

• 49:01Chuck Nice?

  We can get you what you deserve.

• 49:03Neil deGrasse Tyson?

  That's not what we're talking about by space law.

• 49:06Speaker 02

  Actually, it's not far away. I mean, there's a nearest trajectory between Earth and the moon. Who's gonna, is there gonna be toll booths along that? Like, who's gonna police? My brother is co-founder of Carmen Plus, which is an asteroid mining startup. And they're, they have a lawyer on the team.

• 49:23Neil deGrasse Tyson?

  Everyone's brother would be. Yes, we all have that.

• 49:25Speaker 02

  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.

• 49:48Neil deGrasse Tyson?

  Is there a country that's doing that now?

• 49:50Speaker 02

  I think there are. 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.

• 50:14Neil deGrasse Tyson?

  Mm-hmm, mm-hmm.

• 50:16Speaker 02

  Um, this is a real thing.

• 50:16Neil deGrasse Tyson?

  Phone calls have been made, yes.

• 50:18Speaker 02

  Um, we're losing some of our top scholars. I wonder what's going on with that. But the young generation wants to study this. 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...

• 50:41Neil deGrasse Tyson?

  Reminder that when you're young, you're a little more irreverent in your thoughts anyway.

• 50:45Speaker 02

  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.

• 50:52Neil deGrasse Tyson?

  All right.

• 50:52Speaker 02

  Yeah, yeah.

• 50:53Neil deGrasse Tyson?

  Well, at least, thanks for coming back.

• 50:55Speaker 02

  Fascinating. Thanks for inviting me. I, I, I have a good time conversing with you guys.

• 50:59Neil deGrasse Tyson?

  Okay, and you're just up the street. I mean, you're...

• 51:01Speaker 02

  That's true.

• 51:01Neil deGrasse Tyson?

  Right up there, City College is up in 138th Street, uh, right up there in Manhattan, a few miles north of here.

• 51:08Speaker 02

  Can I ask one last question, Neil?

• 51:09Neil deGrasse Tyson?

  I guess so, sure.

• 51:10Speaker 02

  I know you've, 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 you're, like, you, you seem really genuinely curious about these things. What's that about?

• 51:25Neil deGrasse Tyson?

  I would say my, my comments on philosophy have been caricatured.

• 51:29Speaker 02

  Okay.

• 51:30Neil deGrasse Tyson?

  And so I can be very explicit.

• 51:35Speaker 02

  Fair.

• 51:35Neil deGrasse Tyson?

  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.

• 51:50Speaker 02

  Oh, it's been done already. Yeah.

• 51:53Neil deGrasse Tyson?

  I haven't, I haven't.

• 51:54Speaker 02

  But also, I mean.

• 51:56Neil deGrasse Tyson?

  So who was saying it?

• 51:56Speaker 02

  Is the purpose?

• 51:57Neil deGrasse Tyson?

  Is the philosopher saying that or is the physicist saying that?

• 52:01Speaker 02

  The physicists have said that.

• 52:02Neil deGrasse Tyson?

  Okay, so what's the?

• 52:02Speaker 02

  There are contributions.

• 52:03Neil deGrasse Tyson?

  What's the single best example?

• 52:05Speaker 02

  Oh, um.

• 52:06Neil deGrasse Tyson?

  Single best?

• 52:07Speaker 02

  Adam's got one.

• 52:08Neil deGrasse Tyson?

  You're here?

• 52:09Speaker 02

  Nope. I'm calling on my Ask a Friend.

• 52:12Neil deGrasse Tyson?

  Okay, Ask a.

• 52:13Speaker 02

  Phone friend.

• 52:14Neil deGrasse Tyson?

  Get a phone a friend? Phone a friend.

• 52:16Speaker 02

  So Abner Shimonie was a physicist at Boston.

• 52:19Neil deGrasse Tyson?

  Was a physicist? So he's, he's formally trained in, as a philosopher?

• 52:23Speaker 02

  Abner Shimonie has, has formal training in physics and in philosophy.

• 52:27Neil deGrasse Tyson?

  But his PhD is in what?

• 52:28Speaker 02

  Both.

• 52:29Neil deGrasse Tyson?

  What? Well, there you go. He has two PhDs?

• 52:32Speaker 02

  But that's less the point. The point is when you read these papers, the reasoning is philosophical, logical reasoning.

• 52:39Neil deGrasse Tyson?

  Just don't get me wrong.

• 52:40Speaker 02

  Okay.

• 52:41Neil deGrasse Tyson?

  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.

• 52:51Speaker 02

  Good.

• 52:51Neil deGrasse Tyson?

  About what they do.

• 52:52Speaker 02

  Great.

• 52:52Neil deGrasse Tyson?

  And in the field of astrophysics as well.

• 52:55Speaker 02

  Good.

• 52:55Neil deGrasse Tyson?

  There's always a philosophical dimension.

• 52:58Speaker 02

  Sure.

• 52:58Neil deGrasse Tyson?

  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, the academic training in philosophy?

• 53:14Speaker 02

  So this is, this is.

• 53:15Neil deGrasse Tyson?

  So, and I compare modern times to how frequent those contributions came.

• 53:21Speaker 02

  Yep.

• 53:22Neil deGrasse Tyson?

  A century ago. And so if this is the, this is one guy, maybe there's more examples, but I'm, I'm just contrasting.

• 53:28Speaker 02

  Yeah.

• 53:29Neil deGrasse Tyson?

  The utility relative to what role philosophers played back in the day.

• 53:34Speaker 02

  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.

• 53:44Neil deGrasse Tyson?

  Yeah.

• 53:44Speaker 02

  That said, it's still contributed to science, but it is worth doing in its own right. But this, it is worth doing philosophy of science in its own right.

• 53:54Neil deGrasse Tyson?

  I'm not denying that either.

• 53:55Speaker 02

  And I don't think it's also very always quantitative. 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.

• 54:11Neil deGrasse Tyson?

  I never said it wasn't worth pursuing. You've just been shimonied. No, I never said it wasn't. I didn't, I didn't say it wasn't useful as it's 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.

• 54:42Speaker 02

  Have these physicists themselves been trained in philosophy?

• 54:45Neil deGrasse Tyson?

  They might have, but not as if, not as their-

• 54:47Speaker 02

  Not very much. Have they taken philosophy classes?

• 54:49Neil deGrasse Tyson?

  Probably, yes.

• 54:51Speaker 02

  I, I actually maybe an intro philosophy classes undergrads, but I'm willing to bet most of them have not taken a philosophy of science course.

• 54:58Neil deGrasse Tyson?

  Probably most, but some have, sure.

• 55:00Speaker 02

  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. So it may be impossible for those fields to merge again, and maybe that's not the end game, 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.

• 55:41Neil deGrasse Tyson?

  So why isn't this, so then we should, we should promote more of that. 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- And therein lies the problem.

• 55:55Chuck Nice?

  That's what she's saying. That's the problem.

• 55:58Speaker 02

  And then when we do talk to each other, I think, yes, you're gonna find people like, "They don't have anything to do with each other." And you're gonna 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.

• 56:14Neil deGrasse Tyson?

  Maybe what I'm observing is the empirical fact that this doesn't happen.

• 56:22Speaker 02

  Yeah.

• 56:22Neil deGrasse Tyson?

  The philosophy departments don't have lunch with the physicists.

• 56:26Speaker 02

  We should.

• 56:26Neil deGrasse Tyson?

  And so I'm observing that reality and commenting on it.

• 56:31Speaker 02

  Yeah.

• 56:31Neil deGrasse Tyson?

  So that's all it is.

• 56:33Speaker 02

  Yeah.

• 56:33Neil deGrasse Tyson?

  Because I long for the day-

• 56:35Chuck Nice?

  Now that you have observed it, that reality is now entangled for all time. So now it has to happen.

• 56:41Speaker 02

  Actually, it's the observing that would destroy the entanglement.

• 56:43Chuck Nice?

  Oh, that's right. You can't do it anymore. Sorry.

• 56:45Neil deGrasse Tyson?

  The comedic inversion of that. At least, let me get you, take us out with Einstein's comment on philosophy. Do you remember it? Okay?

• 56:54Speaker 02

  He made money.

• 56:55Neil deGrasse Tyson?

  I got my-

• 56:56Speaker 02

  Which one are you hoping for? The history and philosophy?

• 56:58Neil deGrasse Tyson?

  No, no, it's not that deep. This was very, this is 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.

• 57:12Speaker 02

  Where's my book? Hand me my book. I wanna read the quote. One quote from Einstein that's a legit quote.

• 57:16Neil deGrasse Tyson?

  Thanks for reminding me, the Einstein paradox. There's an academic-

• 57:20Speaker 02

  It's an academic text.

• 57:21Neil deGrasse Tyson?

  Academic text.

• 57:22Speaker 02

  It does presume some acquaintance with quantum physics, but just, you know, a scooch.

• 57:31Neil deGrasse Tyson?

  The Einstein paradox, the debate of non-locality and incompleteness in 1935.

• 57:37Speaker 02

  The originators of the theory-

• 57:38Neil deGrasse Tyson?

  This is very like thesis type. This is very, that's like a title of a thesis right there.

• 57:42Speaker 02

  This is intricate work. It is intense work. So this is Einstein writing in June to Schrödinger, trying to figure out what on Earth quantum mechanics means. Dear Schrödinger.

• 57:54Speaker 02

  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.

• 58:13Neil deGrasse Tyson?

  Wow, that's pretty cool. He called him Schröder, not Irwin?

• 58:17Speaker 02

  Didn't I say Dear Irwin?

• 58:19Neil deGrasse Tyson?

  No, you said Dear Schröder.

• 58:20Speaker 02

  No, no, just like buddies. Like, if you're playing a sport, you don't say, "Hello there, Terrence."

• 58:27Speaker 02

  I have, in fact, played sports in my life, despite what that sounded like.

• 58:31Neil deGrasse Tyson?

  Okay, there it is. We've got to wrap this. Well, thanks for this second visit.

• 58:35Speaker 02

  You know what, anytime.

• 58:36Neil deGrasse Tyson?

  To my office here at the Hayden Planetarium. It's great stuff.

• 58:39Speaker 02

  It's good to be back with you guys.

• 58:40Neil deGrasse Tyson?

  Yeah, this has been another installment of StarTalk. Let's call it the Physics of Philosophy Edition.

• 58:49Neil deGrasse Tyson?

  Chuck? Always a pleasure. You are Lord of Comedy. Yes, kneel before me.

• 59:00Neil deGrasse Tyson?

  Until next time, I'm Neil deGrasse Tyson. Keep looking up.