The Limits of Knowing with Elise Crull

Summary

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StarTalk Radio – The Limits of Knowing with Elise Crull

Host: Neil deGrasse Tyson
Guest: Dr. Elise Crull, Associate Professor of Philosophy, CUNY
Co-host: Chuck Nice
Date: November 4, 2025

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Episode Overview

In this episode, Neil deGrasse Tyson and Chuck Nice welcome Dr. Elise Crull back to StarTalk Radio to explore the historic and ongoing relationship between philosophy and physics. The conversation traces how these disciplines have both intertwined and drifted apart, focusing on questions about objectivity, foundational concepts in science, and the particularly thorny issues emerging from quantum mechanics. With humor and depth, this episode sheds light on how we know what we know, the limits of scientific knowledge, and why philosophy still matters to cutting-edge physics today.

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Key Discussion Points & Insights

1. What Is Philosophy Today?

[05:17]

• Dr. Crull describes philosophy as "asking similar questions in always new contexts—scientific, cultural, political—which makes every effort distinct," referencing Bas van Fraassen’s definition.
• Neil reflects on how science and philosophy began as a singular pursuit before professional boundaries emerged.
• Quote:

  "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." — Elise Crull [05:59]

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2. The Shared Evolution of Physics and Philosophy

[07:38] - [15:18]

• The conversation traces the intellectual lineage: Descartes → Newton → Leibniz, highlighting how historical science texts like Newton’s Principia began as works of “natural philosophy.”
• Dr. Crull spotlights Émilie du Châtelet—a pioneering woman physicist/philosopher often overshadowed by her male contemporaries—for her foundational work and her translation/commentary on Newton.
• The need for foundational “rules” (axioms) is fundamental both to philosophy and science.
• Quote:

  “You gotta bite the bullet somewhere. And what follows derives within those constraints.” — Elise Crull [14:10]

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3. Specialization, Fragmentation, and the Wall Between Disciplines

[20:22]

• Dr. Crull and Neil note the increasing specialization of science post-Industrial Revolution, which eroded cross-disciplinary dialogue.
• In the late 19th and 20th centuries, especially after WWII and the Manhattan Project, physics became pragmatic and “bordered,” with a “shut up and calculate” mentality prevailing.
• Historical examples (James Conant’s Harvard program) show attempts to keep philosophy linked to physics.
• Quote:

  “It becomes, in the US, very pragmatic… shut up and calculate mentality. That really dominates through the Cold War era.” — Elise Crull [23:34]

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4. The Role of Philosophy in Scientific Progress

[24:12] - [27:30]

• Neil presses: is this professional wall detrimental? Dr. Crull insists impermeable boundaries harm any field, not just science.
• The utility of philosophical reflection: major paradigm shifts (e.g., Einstein’s special relativity) demanded reevaluation of basic concepts like “simultaneity.”
• Philosophy helps scientists challenge unexamined assumptions.
• Quote:

  “Are we really understanding this concept the way we should be?... We’re getting into regimes in physics where we’re beyond what is empirically testable… What then do you use?” — Elise Crull [28:09]

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5. Objectivity, Measurement, and Quantum Weirdness

[34:01]

• Objectivity—once considered an untouchable hallmark of science—faces new challenges in quantum mechanics, where observer and apparatus can’t be wholly separated from the system.
• The idea of “decoherence” (how quantum systems appear classical at larger scales) and entanglement/nonlocality are unpacked.
• Neil asks: can quantum physics ever be as intuitive as classical physics?
• Quote:

  “When systems interact, something weirdly different happens… You can no longer talk about the physics of one without considering the other.” — Elise Crull [38:02]

• Memorable Analogy:

  “If you want to study a bird, you can watch it fly… but you also need to dissect it... but then it’s not the bird you were studying.” — Elise Crull [35:07]

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6. Quantum Entanglement & Nonlocality

[45:15] - [49:52]

• Dr. Crull recounts how even Nobel Prize-winning physicists disagree on what “nonlocality” actually means.
• Nonlocality: entangled particles are not just correlated but linked in ways that defy explanation by classical signal exchange—even after interaction ceases.
• They reject the “wormhole” as an easy explanation, noting entanglement is too ubiquitous and flexible for that.
• Quote:

  “Entanglement understood as nonseparability… is the thing that causes departure between classical theories and quantum theories.” — Elise Crull [38:02]

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7. Can Philosophy Still Contribute Directly to Physics?

[58:25] - [63:08]

• Neil poses his skepticism: can modern philosophy contribute materially to physical science as it did in the past?
• Dr. Crull counters that the boundary between philosophical and scientific reasoning is blurry, and that today’s best philosophers of science are scientifically literate and intertwined with the work of practicing scientists.
• Chuck Nice highlights that these boundaries themselves may be the problem.
• Quote:

  “There’s just different ways of viewing the world… when we have conversations, it’s interesting, and we learn things. It is a dialectic.” — Elise Crull [62:15]

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8. What’s the Future? Is Quantum Physics Ever “Intuitive”?

[51:43] - [55:51]

• Dr. Crull contends that quantum mechanics will likely never be as intuitive as classical physics because our brains evolved in a classical world.
• Philosophy’s function is to help unmoor scientists from ingrained assumptions.
• Younger scientists show more interest in philosophical context, meaning more cross-dialogue may be coming.
• Quote:

  “Knowing quantum theory is evolutionarily maladaptive… nerds like myself doing problem sets, and here comes the saber-toothed tiger…” — Elise Crull [53:17]
  “There’s a way that quantum is never gonna be intuitive to us the way it is. But that’s why engaging with these philosophical questions [matters].” — Elise Crull [54:09]

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Notable Quotes & Memorable Moments

• On change and humility:

  “People who think hard are the ones who change their minds the most, because I think there's a bit of humility there.” — Elise Crull [06:27]

• On specialization:

  “Liberal arts training is being kicked like a poor little puppy.” — Elise Crull [22:10]

• On the ambitions of science:

  "There's no reason why nature should give a damn about our aesthetics." — Neil deGrasse Tyson [26:00]

• Einstein to Schrödinger (letter):

  “Physics is a kind of metaphysics… we do not know what reality is. We know it only through our physical description. They are wedded together.” — Albert Einstein (read by Elise Crull) [65:17]

• On collaboration:

  “Let's all—who cares where it comes from? All hands on deck.” — Chuck Nice [50:10]

• On ossification:

  “It’s like…an ossification that happens because of the practice itself, and then…philosophy comes in to help change the thinking altogether.” — Chuck Nice [55:12]

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Significant Segments & Timestamps

• [05:17] – What is philosophy? (Bas van Fraassen’s definition; philosophy evolves contextually)
• [07:38] – How physics grew out of philosophy; Descartes, Newton, Leibniz, and women in early philosophy
• [22:10] – How specialization and university structures discourage broad, interdisciplinary thinking
• [24:12] – The “wall” between modern physics and philosophy; when and why it formed
• [28:09] – The importance of philosophical challenges to scientific concepts; Einstein as a philosopher-physicist
• [34:01] – How objectivity is challenged by quantum mechanics; measurement and the observer effect
• [38:02] – Entanglement and nonlocality; why quantum is so weird
• [45:15] – Modern debate about the meaning of nonlocality, even amongst Nobel laureates; experiments and implications
• [51:43] – Can quantum physics ever be made intuitive? Why our minds resist it
• [58:25] – The ongoing value (and limitations) of philosophy for scientific progress
• [65:17] – Einstein’s letter: “Physics is a kind of metaphysics...”

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Tone & Style

The episode blends deep, academic discussion with StarTalk’s signature wit and accessibility. Neil’s curiosity and skepticism blend with Chuck’s comic relief, while Dr. Crull’s expertise keeps the discussion grounded in real history and the lived experience of scientific inquiry. The tone is conversational, lively, and studded with candid admissions about the frustrations and exhilarations of pushing at the limits of human knowledge.

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Summary Takeaway

This episode makes a compelling case that philosophy and physics, though distinct in modern academia, are far richer when brought into conversation. Science is always embedded in philosophical assumptions—about truth, objectivity, and what counts as explanation. As quantum physics continues to challenge our intuitions and technical boundaries, philosophical thinking and cross-disciplinary dialogue will only become more vital. As Elise Crull demonstrates, asking “why” is never out of date, and the “limits of knowing” are exactly where the most exciting discoveries—and debates—are happening.

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Transcript

[Neil deGrasse Tyson]

Howdy, partner.

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[Chuck Nice]

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[Neil deGrasse Tyson]

Philosophy in the house.

[Chuck Nice]

Yes. Along with physics.

[Neil deGrasse Tyson]

Yes.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

And they, they.

[Chuck Nice]

They're the Reese's pieces of science. They belong together.

[Neil deGrasse Tyson]

Maybe physics and philosophy are entangled.

[Chuck Nice]

Ooh.

[Neil deGrasse Tyson]

More on that coming up. Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalking. Neil DeGrasse Tyson, you're a personal astrophysicist. Got with me Chuck Knight, baby.

[Chuck Nice]

Hey, hey, hey.

[Neil deGrasse Tyson]

Lord of Comedy.

[Chuck Nice]

You know, that sounds so.

[Neil deGrasse Tyson]

It does sound, like, pretentious, but people call you Lord nice. And.

[Chuck Nice]

Yes.

[Neil deGrasse Tyson]

So why not run it? Run its course.

[Chuck Nice]

Yeah. I am the. Because it sounds like I should say, I am the Lord of Comedy. Like when people are like, lord nice, that sounds kind of cool. You know what I mean? It sounds like a term of endearment. More so than the title.

[Neil deGrasse Tyson]

The way they say, I got you, I got you.

[Chuck Nice]

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

[Neil deGrasse Tyson]

Bend the knee.

[Chuck Nice]

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

[Neil deGrasse Tyson]

We're revisiting the philosophy of physics.

[Chuck Nice]

All right, all right. Couldn't get enough the first time.

[Neil deGrasse Tyson]

It triggered a lot of interest. Okay. More than I expected or anticipated. And so a lot of people like philosophy? I think so.

[Chuck Nice]

Did you bullshit today?

[Neil deGrasse Tyson]

What does that.

[Chuck Nice]

Are you planning on bullshitting?

[Neil deGrasse Tyson]

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

[Elise Kroll]

Hey, everybody.

[Neil deGrasse Tyson]

Have you bullshitted today yet?

[Elise Kroll]

Yes, but not about philosophy.

[Chuck Nice]

All right, all right, Good answer.

[Neil deGrasse Tyson]

So let's remind people.

[Chuck Nice]

Good answer.

[Neil deGrasse Tyson]

So you're associate professor of philosophy at cuny City University of New York City. 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?

[Elise Kroll]

There's some history.

[Neil deGrasse Tyson]

Oh, history.

[Elise Kroll]

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

[Neil deGrasse Tyson]

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

[Elise Kroll]

Is that the history and philosophy of quantum.

[Neil deGrasse Tyson]

And philosophy and quantum physics?

[Elise Kroll]

Yeah.

[Neil deGrasse Tyson]

Because there's a lot of room to philosophize there, let me tell you.

[Elise Kroll]

Yes.

[Neil 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, but you're the guest.

[Chuck Nice]

That's hard to believe.

[Neil deGrasse Tyson]

No, no, hard to believe that I.

[Elise Kroll]

Look, I'm gonna choose to understand it as. I mean, you guys have a great rapport and what I do is intrinsically interesting. So it gets.

[Neil deGrasse Tyson]

We were all in it.

[Elise Kroll]

We were in it.

[Neil deGrasse Tyson]

I was totally in it. But I wanna make sure. Cause I'm an educ. And I want to make sure that people come into this conversation more thoroughly informed so that they can become enlightened.

[Elise Kroll]

I appreciate that, Neil. Thanks.

[Neil deGrasse Tyson]

So let's just at the risk of sounding too pedantic, tell us what philosophy is. Let me be more precise. What is philosophy today compared with maybe 100 years ago, 200, 300 years ago, back to Aristotle and the famous sort of Greek philosophers.

[Elise Kroll]

Right. So 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 time.

[Neil deGrasse Tyson]

We got other jokes coming here. We're good. We're good.

[Elise Kroll]

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 Basvin Frazen, who also.

[Neil deGrasse Tyson]

What's the name, let me tell you.

[Chuck Nice]

Bassen Frassen. It sounds like a Haagen Dazs ice cream.

[Elise Kroll]

Well, you know what? Haagen. Yeah, they made that up, the Umlas on the road. Like, they're like. Let us sound European to sell our pecan ice cream.

[Neil deGrasse Tyson]

Haagens are made in Jersey. Haagenhaus. Made in Jersey.

[Elise Kroll]

Sintrasn 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.

[Neil deGrasse Tyson]

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

[Elise Kroll]

I think one thing, we tend to look really hard for coherent thought across a person's lifetime. But why should we expect that? Right? 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, they 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 and specialized. 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 Poincare and Lorentz, who are.

[Neil deGrasse Tyson]

And machine one, Mach two, speed of sound. Mach, speed of sound in a medium. Yeah, that same Mach.

[Elise Kroll]

That same Mach. They were philosopher physicists.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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 cat. 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 the Principia, so I've forgotten, by the way.

[Neil deGrasse Tyson]

Yeah, yeah. So what you're saying is Newton's famous work postdates Descartes famous work and he's. Is he poking fun at the title and making it more of a product?

[Elise Kroll]

He's trying to replace it.

[Neil deGrasse Tyson]

Replace it, Right.

[Elise Kroll]

This is what they build on it.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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?

[Neil deGrasse Tyson]

Which book has the I think, therefore I am?

[Elise Kroll]

That is in the Meditations, which was published a few years before, in 41.

[Neil deGrasse Tyson]

She was already trying to go there.

[Elise Kroll]

So book one of the principles is like a polished version of the Meditations. 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, Poincare argues are not helpful. And there's a way that that's true. And then there's the General Scholium, which means explanation. And the General Scholium 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.

[Neil deGrasse Tyson]

And gravity would come in there, and.

[Elise Kroll]

Gravity is even later down the line.

[Neil deGrasse Tyson]

Right, right.

[Elise Kroll]

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

[Chuck Nice]

We know how you know what you know.

[Neil deGrasse Tyson]

Okay, so.

[Elise Kroll]

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.

[Chuck Nice]

I don't know.

[Neil deGrasse Tyson]

I would say.

[Elise Kroll]

Which is right.

[Neil deGrasse Tyson]

Did he give the right answer to that?

[Elise Kroll]

Yeah. Okay.

[Neil deGrasse Tyson]

So through that period, the various folks who are Trying to do. Physics 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.

[Elise Kroll]

Scientific Revolution time. Also actual revolution time for a variety of countries. Also America. Yeah, America.

[Neil deGrasse Tyson]

Merc, Merica and America. And of course, France.

[Elise Kroll]

Liberty. Fraternity.

[Chuck Nice]

Liberty.

[Elise Kroll]

That's right. Tobacco. Wait, I don't know. I don't know how to say tobacco in France, which is probably a good thing.

[Chuck Nice]

Keep your stinking freedom fries.

[Elise Kroll]

Because we didn't like the idea of a monarchy. That's our history, rebelling against a monarchy. Anyway, I see what you did there. They're writing to each other and corresponding and setting up experiments. Boyle, Gassendi, 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.

[Chuck Nice]

Okay.

[Elise Kroll]

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 du Chatelet, who wrote a book called the Foundations of Physics. Ooh, right. So before, you know, maybe.

[Neil deGrasse Tyson]

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

[Elise Kroll]

She's in the mid-1700s.

[Neil deGrasse Tyson]

Thank you for that.

[Elise Kroll]

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

[Chuck Nice]

Salons, salons.

[Elise Kroll]

That's how I feel about. I don't know. I don't know how to say French things.

[Neil deGrasse Tyson]

I want to make sure the timeline is established here. So Newton's greatest work was done in the 1600s. 1686, spilling into early 1700s. Early 1700s. Voltaire comes around mid-1700s.

[Elise Kroll]

A little earlier.

[Neil deGrasse Tyson]

Yeah, a little earlier, I think. And so. And you're.

[Elise Kroll]

And Du Chatelet is the same time.

[Neil deGrasse Tyson]

Du Chatelet. And so they're. They're coincident in time.

[Elise Kroll]

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 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.

[Neil deGrasse Tyson]

One does as one does. You did that with your kids too.

[Chuck Nice]

You see all the textbooks my kids are reading? They're all wr.

[Elise Kroll]

I wrote it. You put as like. The byline is like Lord of comedy, comma, your father. Yeah. Anyway, 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.

[Neil deGrasse Tyson]

Wait, law of. Do they declaring that it's a law.

[Elise Kroll]

It's an axiom.

[Neil deGrasse Tyson]

Okay.

[Elise Kroll]

You have to start somewhere.

[Neil deGrasse Tyson]

Okay, so you lay down some rules.

[Elise Kroll]

That's right.

[Neil deGrasse Tyson]

Rules and regulations.

[Elise Kroll]

Yeah, you gotta bite the bullet somewhere.

[Neil deGrasse Tyson]

And what follows derives within those constraints.

[Elise Kroll]

Yes.

[Neil deGrasse Tyson]

Okay, gotcha.

[Elise Kroll]

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. And so it was her physics that has trained.

[Neil deGrasse Tyson]

Pull out Newton. Say Newton, you need help.

[Chuck Nice]

Here's what you left out.

[Neil deGrasse Tyson]

Newton.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

And how many lady physicists existed at the time.

[Elise Kroll]

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, I'm not sure I know any. There are a lot of women doing philosophy.

[Chuck Nice]

Wow.

[Elise Kroll]

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

[Neil deGrasse Tyson]

Interesting, because I have a book which is Leibniz's letters, and there's all manner of people that are on the other side of those letters. I'll take another look at them. Why? We all know Leibniz today. Just tell Chuck.

[Elise Kroll]

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, he thought that space was not a substance, it wasn't a thing. It was just the relationships between stuff. A 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 Leibniz, it just is how we understand the difference between the distance between matter.

[Chuck Nice]

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

[Neil deGrasse Tyson]

You know, they're different because all the notation is different. And in physics, we retain a lot of Newton's notations, but in pure math, it's all Leibniz's. You know, the integral signs and all these squiggly symbols. That's Leibniz. Yeah, that'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.

[Chuck Nice]

All right.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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

[Chuck Nice]

I didn't. That's the thing I never thought I'd hear this morning. I love that when I woke up this morning, that's what I thought I'd never hear here.

[Neil deGrasse Tyson]

Is that a bumper sticker on your car?

[Elise Kroll]

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

[Neil deGrasse Tyson]

All right.

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[Neil deGrasse Tyson]

Howdy partner.

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[Chuck Nice]

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

[Neil deGrasse Tyson]

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

[Elise Kroll]

As technology gets better, we get we're able Industrial revolution. Yes. And all these like we start moving from talking about forces and inertia and stuff we 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. 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. This is not possible.

[Neil deGrasse Tyson]

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

[Elise Kroll]

Really?

[Neil deGrasse Tyson]

In 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.

[Chuck Nice]

Yeah, well, that's because it was all handwritten.

[Neil deGrasse Tyson]

Real slow.

[Elise Kroll]

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

[Chuck Nice]

They go into these communities. When does all of this lead to what we are? Cause none of this stuff is cross pollinating today.

[Elise Kroll]

Well, I wouldn't say none of it is. I would say it's harder to do. 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. Liberal arts training is being kicked like a poor little puppy. And it's such an important thing. 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. You would learn everything.

[Neil deGrasse Tyson]

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

[Elise Kroll]

Yeah, it kept you learning a bunch of other stuff.

[Neil deGrasse Tyson]

Other stuff. Just the dimensions of life and of society.

[Elise Kroll]

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, 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 bring home the bacon. Right. If you actually did physics at that.

[Neil deGrasse Tyson]

Point, physics is making bombs. They're important for national security. And no one is talking about philosophy at that point.

[Elise Kroll]

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

[Neil deGrasse Tyson]

I didn't remember that, by the way.

[Elise Kroll]

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.

[Neil 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 where other ways of thinking can't get in. And you're saying that's to the detriment of physics, not to the detriment of other fields. How would you characterize that?

[Elise Kroll]

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

[Chuck Nice]

I think walls are very good.

[Neil deGrasse Tyson]

Stop it.

[Elise Kroll]

Stop.

[Neil deGrasse Tyson]

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

[Elise Kroll]

It makes sense because 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. So, I mean, the blossoming of many flowers is a good thing.

[Neil deGrasse Tyson]

So how do we use you?

[Elise Kroll]

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

[Neil deGrasse Tyson]

Okay, okay, sorry.

[Elise Kroll]

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

[Neil deGrasse Tyson]

It came out wrong.

[Elise Kroll]

I know what you mean.

[Neil deGrasse Tyson]

How do you help us?

[Elise Kroll]

Okay. We help each other when we share ideas, when we 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 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, about our aesthetics. Yeah, right. 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. 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 going to work in absolute space and time. 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 reevaluate the basic concepts.

[Neil 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. 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.

[Elise Kroll]

Yeah.

[Neil deGrasse Tyson]

Right.

[Elise Kroll]

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

[Neil deGrasse Tyson]

These are not questions physicists typically ask.

[Elise Kroll]

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

[Neil deGrasse Tyson]

People at the time.

[Elise Kroll]

A century ago. Yeah, that's right. So that it's not. 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 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. 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? 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.

[Neil deGrasse Tyson]

So Brian Greene's bestselling book, the Elegant Universe, Just in all fairness to him, that was not his original title.

[Elise Kroll]

What was it?

[Neil deGrasse Tyson]

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

[Chuck Nice]

Yeah, well.

[Neil deGrasse Tyson]

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.

[Chuck Nice]

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

[Neil deGrasse Tyson]

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

[Elise Kroll]

Well, you shouldn't. 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 or just because then it affects.

[Neil deGrasse Tyson]

Who you hire into departments.

[Elise Kroll]

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

[Chuck Nice]

It shapes your whole outlook on how you're gonna approach Everything.

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Right.

[Chuck 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.

[Elise Kroll]

Right. Or, I mean, 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.

[Chuck Nice]

What Ryan Green does, he's saying, please.

[Neil deGrasse Tyson]

I'm pretending I don't have any idea.

[Chuck Nice]

What you are talking about right now.

[Neil deGrasse Tyson]

Different approaches to solving a problem that we know exists.

[Elise Kroll]

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.

[Chuck Nice]

Okay, that's.

[Elise Kroll]

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

[Chuck Nice]

Heard that.

[Neil deGrasse Tyson]

Go ahead.

[Elise Kroll]

Okay. The canonical approaches say we think quantum theory is the most fundamental theory. So we're going to try and bring GR into that framework.

[Chuck Nice]

Gotcha.

[Elise Kroll]

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

[Neil deGrasse Tyson]

Well, can I tell you why I'm leaning that way? Because no one has ever found a 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.

[Elise Kroll]

It fails if you can't calculate, you know, stuff about black holes. Get out.

[Chuck Nice]

No, no.

[Elise Kroll]

Get out of physics.

[Neil deGrasse Tyson]

No, no, no, no. What I'm saying is not people.

[Elise Kroll]

I'm not talking about people. I'm talking about Abstract.

[Neil deGrasse Tyson]

And what I'm saying is, if you already know. If you already know the limits of general relativity and you don't know the limits of quantum physics because you've never seen the limit. I'm thinking quantum is more badass.

[Chuck Nice]

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

[Neil deGrasse Tyson]

Or, of course, there could be a third entity. Could be a whole. That's worse than both.

[Elise Kroll]

Yeah. 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 ask the person on the street, what are the adjectives that describe science? And they're like, well, it has, like a corner on truth, maybe, but science has, like, this corner on capital T, truth. And there are. 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. How would you know, as one single person, even that this is a special kind of truth? Now, it's true that we have.

[Neil deGrasse Tyson]

How true is it?

[Elise Kroll]

Empirical, medium, capital T. Like, the slash is somewhere between.

[Neil deGrasse Tyson]

Okay, we're quasi. They're different sizes.

[Chuck Nice]

T's.

[Neil deGrasse Tyson]

To begin the word truth, I'm saying.

[Elise Kroll]

Like, you know, 50. 50. I don't know, like 20 proof. That is weak sauce. Anyway, 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 question, blow it with hot air, like, see what comes out. And that's how you do physics. 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.

[Neil deGrasse Tyson]

It's a measurement problem.

[Elise Kroll]

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, he.

[Chuck Nice]

Can'T fly around anymore.

[Elise Kroll]

I didn't want that happening.

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Right.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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

[Neil 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. You just influenced the thing you were trying to understand.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

And hence the idea of an objective truth.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

100 years ago. We're in the centennial.

[Elise Kroll]

That's right. It is the hundredth anniversary of Quantum.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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 every year.

[Neil deGrasse Tyson]

And Hubble discovers that we're not the only galaxy. Wow. 1826.

[Elise Kroll]

There's always something to celebrate, right?

[Neil deGrasse Tyson]

1926. Right.

[Elise Kroll]

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 quotiented out. And so this is something that Einstein continued to look for. In particular, he thought that 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.

[Neil deGrasse Tyson]

Did you just use the word bijectively?

[Elise Kroll]

Yeah, sorry about that.

[Neil deGrasse Tyson]

That's a word.

[Elise Kroll]

It just means in both directions like that you can read from the math to the world or from the world to the math.

[Neil deGrasse Tyson]

Interesting that there's a nice correspondence bijectively.

[Chuck Nice]

Cool.

[Elise Kroll]

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 Schrodinger's way of mechanics, you can't do that anymore. Because once 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, a description mathematically of this guy over here that doesn't make reference to this guy over here.

[Chuck Nice]

Oh, that's.

[Elise Kroll]

They're totally separable.

[Chuck Nice]

That's kind of an issue, right?

[Elise Kroll]

It is. It's his. Because entanglement understood as non separability, right? In fact, it means thereafter there's a quantum interaction and it's a new kind of thing that it's not mechanical, it's not thermal. Like, okay, so you don't even have.

[Neil deGrasse Tyson]

To like, it's a new thing.

[Elise Kroll]

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, without.

[Chuck Nice]

Considering the other or referencing. That's right, because. Wow, that's wild.

[Elise Kroll]

It is wild.

[Chuck Nice]

I love it.

[Neil 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. They're talking about the macroscopic, classical physical world. Right.

[Chuck 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?

[Elise Kroll]

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?

[Chuck Nice]

Well, yes, a bunch of the really small stuff. Right.

[Elise Kroll]

So there's a way that Schrodinger's description, 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, 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 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.

[Neil deGrasse Tyson]

It's a blunt instrument.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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

[Neil deGrasse Tyson]

Decoherence, sure.

[Chuck Nice]

What is that process?

[Elise Kroll]

Yeah, entanglement itself, when you. Well, it's the same problem about objectivity. But first of all, I just want to. Clearly, Bohr never. In his post World War II 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. 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. That. So there's this pragmatic aspect of what he's saying. It's 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 this quantum mechanical. It's because the things, the quantum systems we're looking at are in fact interacting with lots of other stuff.

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[Chuck Nice]

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[Neil 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?

[Elise Kroll]

It depends.

[Neil deGrasse Tyson]

Sorry. Are they headed to a place? Is that a goal at all?

[Elise Kroll]

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.

[Neil deGrasse Tyson]

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

[Elise Kroll]

But I mean I was at the hundredth 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 where do you.

[Neil deGrasse Tyson]

Get all the scoop on people.

[Elise Kroll]

And I'm going to tell you, I read their letters.

[Neil deGrasse Tyson]

Oh, the letter.

[Chuck Nice]

Let me just.

[Neil deGrasse Tyson]

Because not in their books. Yeah, right.

[Chuck Nice]

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

[Elise Kroll]

You can't do a quantum. 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 nonlocality, which I would characterize as 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.

[Neil deGrasse Tyson]

Okay, so tell us what nonlocality means.

[Elise Kroll]

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

[Neil deGrasse Tyson]

Okay, so nonlocality means these two particles that are entangled cannot be described independently of each other. So this is not local. It is connected.

[Elise Kroll]

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, 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.

[Chuck Nice]

Exactly.

[Elise Kroll]

Right. Okay, that's purely classical, not interesting. What makes it very 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 while they're in flight, we can ever over at our measuring device for this guy, set it to measure some quantity or other spin with respect to some angle or something.

[Neil deGrasse Tyson]

Measuring a quantum property of that entity.

[Elise Kroll]

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

[Chuck Nice]

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

[Neil deGrasse Tyson]

So therefore it's not local.

[Elise Kroll]

That is the nominal. 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. The correlations exceed just statistical randomness. Can you can't be talking to each other, can you?

[Neil deGrasse Tyson]

One day.

[Chuck Nice]

That's what there you go, they can't.

[Elise Kroll]

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, at least.

[Neil deGrasse Tyson]

Why not go. Go full Monty here and say, the two particles are connected via wormhole.

[Elise Kroll]

So there are. We could give alternate explanations. But wormholes are way. They would have other effects. Effect wouldn't. Like, they would just.

[Neil deGrasse Tyson]

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.

[Elise Kroll]

I think it would be hard because entanglement nonlocality 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, occur whenever. But also, entanglement 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.

[Neil 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 decoded. They're no longer coherent.

[Elise Kroll]

Yeah. They're no longer entangled after you've done that measurement.

[Neil deGrasse Tyson]

Now they're local particles.

[Elise Kroll]

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.

[Neil 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?

[Elise Kroll]

I think we could use all the help we can get.

[Chuck Nice]

Let's all it. Who cares where it comes from? All hands on deck.

[Neil deGrasse Tyson]

All hands on deck.

[Chuck Nice]

I mean, I'm sorry, because I'm still. You guys were moving very quick, and I'm the guy sitting here without any PhD of anything, so.

[Neil deGrasse Tyson]

You don't have a PhD.

[Chuck Nice]

Yeah.

[Elise Kroll]

Somebody give this man an honorary.

[Neil deGrasse Tyson]

I know. Yeah. Who invited you?

[Chuck Nice]

Okay, 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?

[Elise Kroll]

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 so you can gather some information but not fully decouple it. And again, the degree matters. Like there are some limits on how entangled certain numbers of states can be with respect to some. This is why we can use entanglement as a resource to help us explore different topologies in holography, which is ads like anti de sitter space and how it relates to conformal field theory, which I don't really know about. And I want to figure out like I gotta get. But they're using entanglement as a way to probe unmeasurable stuff.

[Neil deGrasse Tyson]

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

[Chuck Nice]

That is super cool, man.

[Elise Kroll]

I'm telling you, it's very cool.

[Chuck Nice]

I mean it's unbelievable.

[Elise Kroll]

Yeah.

[Neil 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 units. But maybe God does. Oh, my answer's gone. Maybe God is a gambler and just deal with it.

[Elise Kroll]

Yeah. People have different questions about. About that. So here's another. Like if you're a physicist who does quantum theory 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.

[Neil deGrasse Tyson]

It's statistical.

[Elise Kroll]

Yeah, but, 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 with things we could see and measure and apples and arrows.

[Neil deGrasse Tyson]

We didn't evolve in a quantum state.

[Chuck Nice]

No.

[Elise Kroll]

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 to species.

[Neil deGrasse Tyson]

Summarily removed from the gene pool. Yeah, I think so.

[Elise Kroll]

It's a Good thing for physicists.

[Neil deGrasse Tyson]

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

[Elise Kroll]

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?

[Neil deGrasse Tyson]

Yeah.

[Elise Kroll]

Biology is not my area of expertise.

[Chuck Nice]

But I got news for you. The regular tigers don't make a difference. They're good enough.

[Elise Kroll]

Whale sharks and things.

[Neil deGrasse Tyson]

They'll eat you too. Plus they're on the list for becoming de. Extincted. The sabertooth tiger.

[Elise Kroll]

Well, the fact that we can do that now. So cool. So there's a way that quantum is never gonna 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? Are we using these in a consistent way when we set up our experiments? Are we testing our assumptions like these conversations? We're so wedded to the classical picture of things that understanding it's not our.

[Neil deGrasse Tyson]

Fault we evolved that way.

[Elise Kroll]

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

[Neil deGrasse Tyson]

I like that phrase, unmooring. So, okay, all hands on deck.

[Elise Kroll]

Keep doing it.

[Chuck Nice]

No, it makes sense. I mean, it's like you're really. It's kind of a. You know, and ossification. That happens.

[Elise Kroll]

That's another really good word, you know.

[Chuck Nice]

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.

[Elise Kroll]

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 we've.

[Neil deGrasse Tyson]

Ethical philosophy, religious philosophy, even economic philosophy.

[Elise Kroll]

Philosophy of law, philosophy of the emotions, like these things can stay pretty.

[Neil deGrasse Tyson]

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

[Elise Kroll]

Really.

[Neil deGrasse Tyson]

Who owns the moon?

[Elise Kroll]

Every time I. Every time I meet a lawyer, I ask if they're a maritime lawyer because they're going to be the first ones who like develop. They're going to be the ones. Yeah. A good friend.

[Chuck Nice]

Has your satellite crashed into another satellite?

[Elise Kroll]

No.

[Chuck Nice]

Listen, we can get you what you deserve.

[Neil deGrasse Tyson]

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

[Elise Kroll]

Actually it's not far away. I mean look, 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.

[Neil deGrasse Tyson]

And they have a loyalty as everyone's brother would be. Yes, we all have.

[Elise Kroll]

And what they do is super cool. 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? These are really important questions. So. Yes, 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.

[Neil deGrasse Tyson]

Is there a country that's doing that now and we're lagging behind them?

[Elise Kroll]

I think there are, you know, I don't know at the university level. 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. This is a real thing.

[Neil deGrasse Tyson]

Phone calls have been made. Yes.

[Elise Kroll]

We're losing some of our top scholars.

[Chuck Nice]

I wonder what's going on with that.

[Elise Kroll]

But the young generation wants to study this. They are interested in knowing these things because they understand how wedded it is to 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.

[Neil deGrasse Tyson]

And it will a reminder that when you're young, you're a little more irreverent in your thoughts anyway.

[Elise Kroll]

Yeah. 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.

[Chuck Nice]

All right.

[Elise Kroll]

Yeah. Yeah.

[Neil deGrasse Tyson]

Well at least thanks for coming back.

[Chuck Nice]

Fascinating.

[Elise Kroll]

Thanks for inviting me. I have a good time conversing with.

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You all the time.

[Neil deGrasse Tyson]

Okay. And you're just up the street. I mean you're right up there. City College is up in 138th Street. Right up there in Manhattan, a few miles north of here.

[Elise Kroll]

Can I ask one last question, Neil?

[Neil deGrasse Tyson]

I guess so. Sure.

[Elise Kroll]

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 you seem really genuinely curious about these things. What's that about?

[Neil deGrasse Tyson]

I would say my comments on philosophy have been caricatured.

[Elise Kroll]

Okay.

[Neil deGrasse Tyson]

And so I can be very explicit there. Okay. I have yet to see someone who has earned a Ph.D. in a philosophy department in the 20th century contribute materially to our understanding of the physical sciences.

[Elise Kroll]

Oh, it's been done already. Yeah, I just haven't.

[Neil deGrasse Tyson]

I haven't.

[Elise Kroll]

But also, I mean, so who was.

[Neil deGrasse Tyson]

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

[Elise Kroll]

The physicists have said that there are contradictions.

[Neil deGrasse Tyson]

What's the single best example?

[Chuck Nice]

Oh, single best.

[Elise Kroll]

Adam's got one.

[Neil deGrasse Tyson]

You're here.

[Elise Kroll]

No, I'm calling on my. Ask a friend.

[Neil deGrasse Tyson]

Okay, that's good.

[Elise Kroll]

Phone a friend.

[Chuck Nice]

I gotta phone a friend.

[Neil deGrasse Tyson]

Phone a friend.

[Elise Kroll]

So Abner Shamoni was a physicist at Boston.

[Neil deGrasse Tyson]

He's a physicist. So he's formally trained in. As a philosopher.

[Elise Kroll]

Abner Shamoni has formal training in physics and in philosophy, but his PhD is in what, both.

[Neil deGrasse Tyson]

What?

[Chuck Nice]

Well, there you go.

[Neil deGrasse Tyson]

He has two PhDs.

[Elise Kroll]

That's the point. The point is, when you read these papers, the reasoning is philosophical. Logical reasoning.

[Neil deGrasse Tyson]

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.

[Elise Kroll]

Great.

[Chuck Nice]

And.

[Neil deGrasse Tyson]

And in the field of astrophysics as well.

[Elise Kroll]

Good.

[Neil deGrasse Tyson]

There's always a philosophical dimension. So the precision of my comment about philosophy has just been, what is the value to the physical scientist of someone who's spent their entire career, academic training in philosophy?

[Chuck Nice]

So this is.

[Neil deGrasse Tyson]

And I compare modern times to how frequent those contributions came a century ago. And so if this is one guy, maybe there's more examples, but I'm just contrasting the utility relative to what role philosophers played back in the day.

[Elise Kroll]

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

[Neil deGrasse Tyson]

I'm not denying that either.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

I never said it wasn't worth pursuing.

[Chuck Nice]

I've just been shimonied.

[Neil deGrasse Tyson]

No, I never said, 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. And so I just.

[Elise Kroll]

Have these physicists themselves been trained in philosophy?

[Neil deGrasse Tyson]

They might have, but not as a. Not as far, not very much.

[Elise Kroll]

Have they taken philosophy classes?

[Neil deGrasse Tyson]

Probably, yes.

[Elise Kroll]

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

[Neil deGrasse Tyson]

Probably most, but some have, sure.

[Elise Kroll]

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. 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 made. It is all very interesting.

[Neil deGrasse Tyson]

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 the biologist.

[Chuck Nice]

Lies the problem. That's what she's saying. That's the problem, you know.

[Elise Kroll]

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.

[Neil deGrasse Tyson]

Maybe what I'm observing is the empirical fact that this doesn't happen. The philosophy departments don't have lunch with the physicists. We should and so I'm observing that reality and commenting on it.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

So that's all it is.

[Elise Kroll]

Yeah. That's good.

[Neil deGrasse Tyson]

Because I long for the day now.

[Chuck Nice]

That you have observed it, that reality is now entangled forever. So now it has to happen.

[Elise Kroll]

Actually, that's the observing that would destroy the entangle.

[Chuck Nice]

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

[Neil 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. He probably had several.

[Elise Kroll]

He made many. Which one are you hoping for? The History and Philosophy.

[Neil deGrasse Tyson]

No, no, it's not that. 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.

[Elise Kroll]

Where's my book? Hand me my book. I want to read the quote. One quote from Einstein. That's a legit quote.

[Neil deGrasse Tyson]

Thanks for reminding me that The Einstein paradox. There's an academic.

[Elise Kroll]

It's an academic text.

[Neil deGrasse Tyson]

Academic text.

[Elise Kroll]

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

[Neil deGrasse Tyson]

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

[Elise Kroll]

The originator's theory.

[Neil deGrasse Tyson]

This is very. That's like a title of a thesis right there.

[Elise Kroll]

This is intricate work. It is intense work. So this is Einstein writing in June to Schrodinger. I'm 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.

[Chuck Nice]

Wow.

[Elise Kroll]

Inseparable.

[Neil deGrasse Tyson]

That's pretty cool you call him Schrodinger and not Erwin.

[Elise Kroll]

Didn't I say dear Erwin?

[Neil deGrasse Tyson]

No, you said, dear Schrodinger.

[Elise Kroll]

Dear Schrodinger. No, no. Just like buddies. Like, if you're playing a sport, you don't say. Hello there, Terrence. I hope I have, in fact played sports in my life. Despite what that sounded like.

[Neil deGrasse Tyson]

Okay, there it is. We gotta wrap this. Well, thanks for this second visit.

[Elise Kroll]

You know what? Anytime.

[Neil deGrasse Tyson]

To my office here at the Hayden Planetarium.

[Chuck Nice]

It's great stuff.

[Elise Kroll]

It's good to be back with you guys.

[Neil deGrasse Tyson]

Yeah. This has been another installment of StarTalk. Let's call it the Physics of Philosophy edition.

[Chuck Nice]

Chuck, always a pleasure.

[Neil deGrasse Tyson]

You are lord of comedy. Yes.

[Chuck Nice]

Kneel before me.

[Neil deGrasse Tyson]

Until next time. I'm Neil Degrasse. Tyson Keep LOOKING up.

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[Elise Kroll]

Explore what's possible.

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