In search of nothing | David Deutsch, Amanda Gefter, Lee Smolin

Summary

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Podcast Summary

Philosophy For Our Times
Episode: In Search of Nothing | David Deutsch, Amanda Gefter, Lee Smolin
Date: November 6, 2025
Host: IAI (Mato Dowd)
Guests: David Deutsch, Amanda Gefter, Lee Smolin

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Overview

This episode brings together three prominent voices from physics and philosophy—David Deutsch, Amanda Gefter, and Lee Smolin—to explore the profound question: Is nothing an impossibility? The discussion unpacks the concept of “nothing” from both scientific and philosophical perspectives, probing paradoxes, definitions, and the very nature of existence. The panel addresses whether nothingness can exist, if “something” is inevitable, and whether investigating nothing can yield new insights about our universe.

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1. Framing the Debate: What is Nothing?

Start: 01:53

• Host’s Introduction (01:53):
  Sets up nothing as “an absence so absolute that even defining it becomes problematic,” referencing philosophical giants from Hegel to Sartre and raising the paradoxes inherent to the topic.

Opening Responses

• David Deutsch (04:20):

  • Warns against essentialism and dismissing the question as meaningless; instead, real problems arise from the concept of nothing, such as the paradox of time beginning at the Big Bang.
  • Offers the North Pole analogy: asking “what is north of the North Pole?” is a question of terminology, but questions about the structure of the universe (like a torus vs. infinite repetition) are substantive and demand theory.
  • Quote: “Usually a problem is a problem. And unless people are mischievously citing just words, which some philosophers do, then the problem has to be addressed.” (08:05)

• Amanda Gefter (08:23):

  • Recounts her lifelong quest to understand nothingness, sparked by her father’s question at age 15: “How would you define nothing?”
  • Shares a story of John Wheeler’s response: “I like to say the boundary of a boundary is zero,” noting the journey this set her on.
  • Concludes: “What I've come to believe, in a sense, is the opposite of the suggestion…that maybe nothing is the only possibility. And because of that, it's the appearance of something that is inevitable.” (11:00)

• Lee Smolin (11:07):

  • Asserts that none of his developed theories in physics have required a concept of nothing; argues that “nothing exists; things only happen”—the focus should be on change and the rules governing it.
  • Quote: “There’s nothing that we call time which is real, which is really what a plainness would call time. That is, I don’t believe there’s anything that is stationary and unchanging. I think everything changes.” (11:30)

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2. Defining “Nothing”

Theme One, 13:40

Philosophical and Physical Approaches

• Deutsch (14:15):

  • Cautions against “what is” questions without theory; supports Smolin’s view that things happen according to rules, but challenges what happens if rules themselves change.
  • Raises a paradox: “Do the rules which change change according to a rule?” (15:27)

• Smolin (15:27):

  • Reflects on progress through paradox, referencing collaborator Roberto Unger: “Bringing oneself into a deep paradox is progress.”
  • Deutsch retorts (15:57): “We want to be able to come out of a deep paradox as well.”

• Gefter (16:18):

  • Argues that “nothing” defined as a negative (no thing, the absence of everything) leads to logical traps; explores her father's proposal to define nothing positively, as “a state of infinite, boundless sameness.”
  • “I think…still to this day I find that like a useful way to think about nothing as kind of this completely invariant, unchanging sameness.” (17:50)

Physics vs. Philosophy: The Vacuum

17:58

• Host: Notes physicists’ “vacuum” isn’t true nothing; it’s an “active” place with laws of nature operating.

• Smolin (18:31):

  • Discusses “vacuum” as the lowest energy state in quantum mechanics; brings up the “metalog dilemma”—how do the laws of physics arise or evolve?
  • “I think that it's real progress to have arrived at that…to understand why the laws of nature would change as we see them do.” (20:10)

• Deutsch (21:19):

  • Quantum field theory makes “nothing” easier philosophically; echoes Gefter’s “sameness” as requiring less explanation than novelty.
  • Argues that the distinction between sameness and novelty is central not just to cosmology but also free will and consciousness.
  • Quote: “This idea that reality is about the distinction between sameness and novelty…comes into all sorts of other philosophical issues.” (22:58)

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3. Can We Even Talk About “Nothing”?—The Role of Paradox

Theme Two, 30:11

• Host: Quotes Lewis Carroll and Bertrand Russell—can paradoxes of nothing be “corrected” by fixing our language/logic?

• Smolin (30:58):

  • Russell’s view: many “nothing” problems are linguistic errors—fix the grammar, fix the paradox.
  • “I think that Russell is right about many questions in philosophy turn out to be decidable by improving your language.” (31:14)

• Deutsch (31:59):

  • Cautions: “It’s always dangerous to define away a problem…to just throw away that whole situation and say it’s only a matter of words I think is a mistake.”
  • Invokes Kant’s struggles with the universe’s beginning, resolved only with later mathematics—thus, real problems may hide behind verbal paradoxes.
  • Quote: “We shouldn’t just throw away problems.” (33:20)

• Gefter (36:04):

  • Suggests flipping the question: “What is something?” In physics, reality is often what’s invariant in all reference frames. Notably, progress in physics (from Einstein to holography) keeps revealing supposed invariants to be, after all, observer-dependent.
  • “The progression…seems to open up the possibility that eventually what you're going to find is that the only real thing is nothing.” (37:22)

• Smolin (38:44):

  • Adds even solutions in advanced theories like string theory and general relativity lack true invariants, pushing us further from a classical “something” towards this “nothing.”

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4. Observers, Boundaries & Information: John Wheeler’s Legacy

42:26

• Gefter (42:26):

  • Outlines Wheeler’s evolving quest: from particles to spacetime to information as the universe’s foundation.
  • Shares Wheeler’s participatory universe—reality emerges via observers, boundaries (“lines across the empty courtyard”), and relative distinctions; but removing the boundary returns us to nothing.
  • Quote (Wheeler): “There is many a game we cannot play until we draw with chalk a line across the empty courtyard. It doesn't matter where we draw it, but only that we draw it.” (43:00)

• Deutsch (45:57):

  • Critical of Wheeler’s/Bohr’s “information” approach: labels it “supernatural” and “obscurantist,” a means of resisting the many-worlds (Everett) quantum theory.
  • Argues that information is always instantiated on something physical, which itself is not “nothing.”
  • Quote: “Information in the universe is fundamental information, making the universe…That's just all this supernatural stuff.” (47:50)

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5. Does Studying Nothing Help Us Understand the Universe?

Theme Three, 50:24

• Smolin (50:24):

  • Shares story of John Wheeler’s excitement over Heidegger; muses on the usefulness of “European philosophy” despite his scientific skepticism.
  • Celebrates the infinite variety in the world and the endless capacity for discovery, paralleling Leibniz: “There’s something enormously celebratory about the idea that the world is infinite in variety, has infinite capacity to teach us and surprise us.” (54:26)

• Gefter (55:23):

  • Echoes “something is nothing, and nothing is something”—references Alan Guth’s observation that all conserved quantities (charge, angular momentum, energy) in the universe sum to zero; thus, “maybe a better way of saying it is that something is nothing.”
  • Quote (Alan Guth): “Maybe a better way of saying it is that something is nothing.” (57:06)
  • Suggests facts within the universe (everything summing to zero) can point back to the fundamental “nothing.”

• Deutsch (58:28):

  • Concludes that seeking absolute bedrock or foundation for all knowledge is mistaken (aligning with Karl Popper); instead, philosophy and science should seek to resolve problems, not foundational truths, enabling endless progress:
  • Quote: “That is the doorway, the open window, to an infinite progress.” (59:40)

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6. Notable Quotes & Moments

• David Deutsch:
  “We have to start with the problem and what we're looking for when we're trying to solve a problem is, again, not the final answer. It is an explanation that tells us why the conflicts that we thought that we saw aren't really there...That is a good thing, because that is the doorway, the open window, to an infinite progress.” (58:28–59:53)

• Amanda Gefter:
  “What I've come to believe, in a sense, is the opposite of the suggestion…that maybe nothing is the only possibility. And because of that, it's the appearance of something that is inevitable.” (08:23–11:00)
  “If you could take the sort of God's eye view from outside of reality, I think then what you would see is that sameness. You would see the nothing. But by definition, you can't be outside of that…” (26:08)
  “Maybe a better way of saying it is that something is nothing.” — Alan Guth, via Gefter (57:06)

• Lee Smolin:
  “All that exists, first of all, nothing exists. Things only happen, and things that happen happen according to some rules which are developed in time and change in time.” (11:07–11:30)
  “Bringing oneself into a deep paradox is progress.” (15:27)

• John Wheeler (via Gefter):
  “The boundary of a boundary is zero.” (08:23)
  “There is many a game we cannot play until we draw with chalk a line across the empty courtyard. It doesn't matter where we draw it, but only that we draw it.” (43:00)

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7. Key Timestamps

• 04:20 - Deutsch on the Big Bang and the North Pole analogy
• 08:23 - Gefter’s journey and Wheeler anecdote
• 11:07 - Smolin on events vs. existence
• 16:18 - Gefter attempts positive definition of nothing
• 17:58 - Physics vacuum vs. philosophical nothing
• 21:19 - Deutsch on the necessity of novelty and sameness
• 26:08 - Gefter on observer-dependent vacuum states
• 31:59 - Deutsch on not defining away problems
• 36:04 - Gefter: “something” as observer-invariant
• 42:26 - Wheeler’s chalk line and participatory universe
• 55:23 - Gefter on conserved quantities summing to zero
• 58:28–59:53 - Deutsch’s closing remarks on infinite progress

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Conclusion

The episode unearths the central paradox of “nothing”—seen not as a philosophical dead-end, but as a driver for inquiry in both physics and philosophy. Whether defined through invariance, observer-dependence, or the balance of conserved quantities, “nothing” remains a fertile and elusive concept. The panel converge on the notion that genuine progress comes from tackling paradoxes head-on and embracing the infinite complexity of the universe, rather than settling for final answers.

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Transcript

[A]

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[B]

Hello, my name is Matt o', Dowd, and you've tuned into the Institute of Art and Ideas debate in search of nothing. At first sight, the idea of nothing appears as a straightforward concept, being simply the absence of any thing. However, for centuries, philosophers and scientists have grappled with this unexpectedly perplexing idea. Nothing is an absence so absolute that even defining it becomes problematic. We might imagine nothing as the void, the empty vacuum of space. But to be true nothingness, our possible candidate would need to lack time, space, matter, energy, and relation to the rest of the universe. Meanwhile, in philosophy from Hegel to Sartre, many have placed nothing at the center of their philosophical accounts of the world, but do so in part by maintaining the picture of nothing as an unfathomable mystery. So should we conclude that nothing is an impossibility, and if so, that something is inevitable? Can the paradoxes surrounding nothing be written off as a legi dimothe, as Bertrand Russell maintained? Or can we uncover the true nature of nothing, and with it, other mysteries of the universe as well? So today we have three eminent scholars who have thought long and deeply about nothing. Let me rephrase that. They've thought long and deeply about A great many things. And one of those things is the concept of nothing. And so today, to help us understand nothing, we have David Deutsch, a pioneering theoretical physicist best known as the founding father of quantum computation and as a key figure and advocate for the many worlds interpretation of quantum mechanics. And we have Amanda Gefter, a celebrated science writer specializing in fundamental physics, cosmology, cognitive science and philosophy. She is also the author of Trespassing on Einstein's the Story of her quest with her father to figure out the nature of ultimate reality. And finally, Lee Smolin, a renowned theoretical physicist known for his work on loop quantum gravity and more broadly in the philosophy of physics. He challenges mainstream ideas in physics, such as the idea that time is an illusion and that the laws of physics are fixed. So let's get started with our opening question. Is nothing an impossibility? And if so, is something inevitable? David, we'll start with you, then go to Amanda and Lee.

[C]

Okay, well, I think it's important not to lapse into essentialism here, trying to extract the essence of things like, you know, Plato and that, that kind of person, because that leads to thinking that this, this is a non issue, that anyone who tries to ask what nothing is is just talking nonsense. But it does come up in terms of real problems. So for example, 13.8 billion years ago, time began at the Big Bang. And is that a paradox? Well, if something began, then it can't have existed at an earlier time. And if time began, there were no earlier times. Whatever brought about the transition from time not existing to existing must have happened before time existed. Which seems like a contradiction, but it could make sense. For example, it could be that there was no moment of the Big Bang just moments after it, just like there's no smallest positive fraction. And thus there would be no moment before which the universe did not yet exist. So that that would make sense. Is it true? I don't know. But here's a case where we're really talking about nothing. Suppose you're standing at the North Pole and you ask what is north of here? You've been trudging all the way there, you get more and more north. Is it possible to get more north than the North Pole? Is there a barrier there preventing you from going further? Or is it just that one all directions are south and we'll just call one of them north arbitrarily. That is a question of terminology. But a very similar question about the universe is not a matter of terminology. That is, suppose that the universe a Taurus, so that if you went far enough in that direction, you'd come back from that direction. Then is that the same as there being an infinite number of universes, all identical, and you go from one to the other? Is. Is identifying two sides which you can go through the same thing as having an infinite number? Well, there, I don't think it's just a matter of terminology. I think there's a real question there, and it shows you that there has to be a broader theory of what the universe is and what space is. That would tell you whether the real thing is just an infinitely repeated finite segment of space or whether it is just one of them identified. So I would say don't get sucked into the nihilist position that the problem is not a problem. Usually a problem is a problem. And unless people are mischievously citing just words, which some philosophers do, then the problem has to be addressed.

[B]

Let's hope we can at least define our terms better, if not solve the problem today. Thank you, David. Amanda, would you like to address the pitch? Is nothing an impossibility? And if so, is something inevitable?

[A]

This question of what is nothing? Is extremely close to my heart. It's actually the singular question that has driven my entire career. It's what got me interested in physics in the first place. It's how I ended up as a journalist. And, I mean, it's truly shaped my life. I've spent the last 30 years thinking about nothing. And that's because When I was 15 years old, my father, who is this sort of Zen guru, former hippie turned radiologist, took me out to dinner at our favorite Chinese restaurant and asked me, how would you define nothing? And this question was like this spark that set off this crazy journey that led us deep into cutting edge physics. It led us to crash a physics conference in 2002 that was being held in honor of the great physicist John Wheeler. Wheeler. That was where I met Lee Swan for the first time. And Wheeler was this brilliant physicist who had these very radical ideas about the nature of reality. And my dad and I showed up posing as journalists, and I said I was from Manhattan Magazine, which, you know, didn't exist. And we met Wheeler at this meeting and we asked him several questions, but one of them was, is everything from nothing? And Wheeler nodded and said, I like to say the boundary of a boundary is zero. So it was like Yoda answering a physics question, and we had no idea what it meant. And so for the next few decades, well, for one thing, my fake journalism career sort of morphed into a real journalism career. But more importantly, I kept chasing this question about nothing and what I've come to believe after reading through all of Wheeler's personal journals trying to get it. What was he really trying to say? What did he think about nothing. After speaking to so many amazing physicists and immersing myself in today's cutting edge physics and cosmology, what I've come to believe in a sense is the opposite of the suggestion that that's in your question, that maybe nothing is the only possibility. And because of that, it's the appearance of something that is inevitable.

[B]

For now, we should move on to the LI LI.

[D]

I've built several theories of physics, none complete, but some that get us some insight into what the world might be. And none of them had a concept of nothing or required a concept of nothing. I think that you're wrong headed to start at the beginning with that question, because I think the question we should start with is time. And if you get the meaning of time, the construction of the world in time correctly, I'll say what I mean by that in a minute. You don't have to ever encounter the idea of nothing in the physics concept. I'm not going to talk about my Zen Buddhist friends and so forth who are justly on their own path. So I believe that all that exists, first of all, nothing exists. Things only happen, and things that happen happen according to some rules which are developed in time and change in time. So there's nothing that we call time which is real, which is really what a plainness would call time. That is, I don't believe there's anything that is stationary and unchanging. I think everything changes. And our job as physicists is to find out what are the rules under which things might change. And if you go about that seems to me correctly, you don't have to encounter the idea of nothing. So that's where I would start. I don't want to go on and on with that, but that's where I would start with the notion of time. And if you like, with time being the distinction between something unchanging and something changing. And when we have something which changes, we want it to change according to some rules or some happenings. And then we're talking about changes of changes. And that's what I think is interesting. And I think Johnny Wheeler thought that way and he was very confusing certainly, but I think that what he was searching for was an understanding of how change could change. Thank you.

[B]

Wonderful. I really hope we can pick apart some of the potential conflicts here. But for now we're going to move into what we're calling theme one, where we build our definitions and make sure we're speaking in the same language. So theme one is what is nothing? Which we can expand on our earlier statements. And I again want to start with David. David, I invite you to expand and to even address the pictures of your fellow speakers, if you so wish.

[C]

Yeah, I, too, don't think that what is questions are a good place to start because you only find out what something is when you have a theory of it. What is a dog? Well, the only people that can really answer that question are zoologists or veterinarians who deal with dogs, and they can answer such questions. So, coming to what Lee was saying, okay, I don't mind things just happening and not primarily existing. So things happen. If they happen, they happen according to rules. I'm with you that far. The rules can change. I'm with you that far, but I would draw the line at. Well, the question is, do the rules which change change according to a rule? And if that cannot change, so then that's the only thing that can't change this rule that can't change. Or if everything can change, then it's not true that, that everything that changes changes according to a rule.

[D]

Right. And that's a paradox. I wrote a book with Roberto Manguber Unger, who is a very deep philosopher. He thinks about many things, and I certainly admire him. And that's a paradox. According to him, we walk into an instant paradox, and he would argue that bringing oneself into a deep paradox is progress, and that's what you've accomplished.

[C]

And out. We want to be able to come out of a deep paradox as well.

[D]

Well, that's more progress. Seriously, that's how he thinks.

[B]

Amanda, do you have any comments on the pictures or things to expand on right now?

[A]

Sure. I mean, I. I guess in terms of just defining nothing, I, I mean, one of the things that, that my dad and I talked about back in that conversation in the Chinese restaurant was, you know, is. It seems like a lot of the problems that we run into, at least semantically with nothing is. Is, you know, it's defined as an. As a negative. Right. And. And so then if you say nothing is no thing, it's the absence of everything, and then you ask, how does something come from nothing? You've sort of set yourself up to fail. And I think it was William James said something like, from nothing to being, there's no logical bridge. You've just sort of set it up logically. So that it's impossible. And so the thing that my dad was interested in that started that whole conversation was, is there a way to define nothing in the positive if you could just describe its features? What is nothing? I mean, sounds paradoxical to say features, but he said, well, what if you had a state of infinite boundless sameness? I mean, that would really be indistinguishable from a void, right? And so that would be the sort of like the unchangingness against which any kind of change could happen. And so I think, you know, still to this day I find that like a useful way to think about nothing as kind of this completely invariant unchanging sameness. And then anything that we want to say about the universe and what we observe can be sort of set against that.

[B]

Right. And I think when physicists talk about nothing, they mean something a little bit different often to the philosopher, which rather than just being the absence of anything, physicists often use what to them is a more useful term, the idea of the vacuum, the idea of empty space. But such a nothing is a pretty active place. Is there anyone who would care to elaborate on the physicist nothing versus the philosopher's nothing?

[D]

Well, you can go cheap and talk about the vacuum by which we physicists mean the quantum state, which is lowest in energy. And if you get there are questions about how does the vacuum get chosen and why this vacuum and not the other vacuum? And if you go on that further, you go into what Roberto and I call the metalog dilemma. And that is a paradox. There is a paradox of the metal modulema. And I think we have to face it because one place to start is Clariss was a great philosopher, as you know, Pluris said that if we want to understand nature, we have to understand evolution and we have to understand the kind of natural selection of laws of physics. And then we're in the paradox that David pointed out. And I think we are. And I don't know a way out of it, but certainly I have a different instincts perhaps than David. I think that it's real progress to have arrived at that and arrives at a place in physics where we can talk about a version of the men of law dilemma. Kaustin what the laws of physics, how they might be chosen. Because you're not giving up, you're saying in biology we don't give up. When we state the metal dilemma, we say that what we would need to make more progress still is, is to understand why the laws of nature would change as we see them do. And I think that's just where we are.

[B]

So this idea of the vacuum as a thing on which the laws of nature are operating. And in the case of our universe, that means quantum mechanics, which means fluctuations due to the uncertainty principle and particles appearing and disappearing from which much presumably can happen. That, you know, this isn't quite nothing. This is a. First of all, you do have space and time and you do have the laws of physics and the laws of physics themselves be thought out of. Something needs to be explained. And where do, where do laws of physics, even if they do evolve afterwards, as your cosmological natural selection suggests? Well, how do laws of physics spring from nothing? I don't know. Maybe. David, you have ideas?

[C]

Yeah, I think that quantum field theory and so on make this problem of nothing easier, Much easier. Philosophically, it's a much more severe problem to think about the vacuum as it appeared in classical physics. And I think that I'm very sympathetic to Amanda's idea of, of sameness because. And, and you mentioned explanation a moment ago, which, which I think is a key that, that opens many philosophical problems. When something, something is the same, then it doesn't require any more explanation. Like if there's more of it, then, then if, if it's just, if it's just an infinite amount of sameness, then it requires no explanation. So if you say when the universe came into existence, was that, was that something new? Was there novelty there? And that, that's an interesting question. And I think that if you, if you pursue that question, you're led to the answer. It starts being something when there's something new to be explained. If there was just a whole bunch of sameness, then that wouldn't need. It might need one explanation for why it was the same, but after that it wouldn't. Bits of it wouldn't need any further explanation. And I think that this idea that reality is about the distinction between sameness and novelty, it comes into all sorts of other philosophical issues. Like for example, what is free will? What is consciousness? Consciousness is the ability to create something that needs additional explanation. So if, if, if I have an AGI or something and it, and it's, it says a thing which doesn't require any more explanation, then it hasn't really been a gi. But if it says something where you have to say, well, it, he. It, she is. Is the same, is not the same as another instance of that it needs more explanation. Like he is sad, but not the same sadness as someone else has, that that person has a different sadness which we have to distinguish from the earlier sadness, from the other person's sadness by an explanation. So, yeah, I'll stop there.

[B]

So, Lee, of course respond. But one thing, I'd like you if at some point, so I know that you've talked about the idea of nothingness as that which is outside the universe. So if you can also add, I'm curious whether that agrees with the notion of the idea of nothing as sameness.

[D]

Let me quote. I often think about this time, and it's by Werner Heisenberg who said that this formulation makes it clear that the uncertainty relation does not refer to the past. And I think it's very important to separate the past and the future in order to think about these things. Clearly, I disagree. I don't think that I've thought about the outside of the universe. What are the assumptions that I use when I study cosmology? A quantum cosmology is that there is nothing outside the universe. And that's further. The definition of what a universe is, is it's something which has nothing outside of it, there's no cause to it, that comes from outside of it, etc. There's no law which comes from outside, with the law must be understood endogenously, it's coming from the inside.

[B]

Perhaps this is a helpful definition of nothing. If the universe is all that is, then that which is not the universe is nothing, which. I don't know.

[D]

That's a useful move in a discussion about quantum cosmology.

[B]

But Amanda, this seems to conflict with the notion of nothing as sameness.

[A]

I'm not sure it does. I. How do I put this? I mean, I think I thought a lot about Lee's, you know, he said like, the first principle of cosmology must be there's nothing outside the universe. And I guess to cut to like the conclusion, I think it's almost like if you could see, if you could take the sort of God's eye view from outside of reality, I think then what you would see is that sameness. You would see the nothing. But by definition you can't be outside of that because if it's true infinite sameness, then you're swallowed up in the sameness as well, which makes it sort of unobservable, which is why I think the appearance of something becomes inevitable. But maybe I'll just say one quick thing which is like, you know, when we talk about the vacuum, something that I find so interesting in physics, you know, you're talking about the vacuum and these particles appearing and all the activity and everything, but one of the really deep results in quantum gravity. And I think I first learned this from Lee as well, is that the vacuum state is observer dependent. So when we look at, you know, there's things like the Unruh effect and Hawking radiation. And whenever you have quantum fields, like in a curved space time in a. In a universe with gravity, which our universe has, or universe with dark energy, anything where you end up with a horizon, a black hole, it becomes impossible to say in any absolute way like what the vacuum is. The vacuum for an inertial observer is different from a vacuum for an accelerated observer. And there's no. It's not like one observer's right and another observer's wrong. There's just. It's not something that's definable in, like, an absolute way. And I think that's a really deep thing that we've learned from quantum gravity, which is. I mean, if you want to say, like, oh, the vacuum, like, that's the nothing and that's, you know, we're going to base our understanding of the universe on that. You have to ask, you know, from whose perspective, according to who? And again, that comes back to like, you can't take this kind of God's eye view from nowhere. You have to be an observer inside the universe that has a particular perspective. And then the very notion of a vacuum is going to change depending on which perspective you take.

[C]

You've just taken a God's eye view. You talked about all sorts of different people's perspective. And the set of all those perspectives is what you think is the real reality. Just like with the statue, you know, the set of all the perspectives, all the perspectives that there could be on that statue is all we can say about the statue. Not that I shouldn't be defining reality in terms of all we can say, because there's plenty of. Plenty of reality that we can't say anything about, by the way. There's also abstract reality. We say that a second, even prime doesn't exist. It doesn't exist anywhere. So it exists nowhere. Where is that nowhere? In order to avoid paradoxes like that, we have to say that all the numbers exist, even the ones that we can't see. But the ones that we can define that can't exist, they don't exist. They're in some other like. Then we can add them. We can say, the square root of minus one is a new thing that we shall say exists abstractly. So I think we shouldn't leave out abstractions, by the way. The laws of physics are such an Abstraction.

[B]

This is a great time for us to move on to theme two, now that we're getting too small after a topical definition. And so I'm going to start by badly misquoting the great philosopher Lewis Carroll, who wrote, I see nothing on the road, said Alice. I only wish I had such eyes. The King remarked in a fretful tone, to be able to see nothing and at such a distance too. So an even greater philosopher, Bertrand Russell, warned about treating nothing as an object of study as being a logical mistake. So theme two centers around the question of whether the paradoxes surrounding nothing can be dismissed so handily. And I think we all have a lot to say, but I'd like to move to Lee for your thoughts on that.

[D]

Well, I think a lot of the simple questions that Russell and similar language philosophers argued for that when it comes to nothing, you're just using a bad grammar when you say nothing is nothing or nothing exists. But ultimately you solve the problem by improving your grammar. I think that Russell is right about many questions in philosophy turn out to be decidable by improving your alignment. And I particularly like where that leaves us. But I think it is a similar role we have to client in it. I don't know if that helps you.

[B]

I hope it was helpful. So, David, you were talking about the paradoxes of nothing and the reality of nothing. What's your thought?

[C]

I think it's always dangerous to define away a problem if someone has a problem, if someone is wondering what, like I said, if someone's wondering what happened before the Big Bang or what is north of the North Pole, that kind of thing that arises from that, that's a problem which arises from some kind of real conflict between ideas which were originally proposed for some purpose and which seem to serve that purp. And so to just throw away that whole situation and say it's only a matter of words, I think is a mistake. People can say things that are nonsense and are only a matter of words, but it's not always the case. And in particular in regard to nothing, I think behind the apparently nonsensical or the apparently just purely verbal conflicts, there are often real conflicts that have real solutions. And I mentioned also that Immanuel Kant was perturbed by things like that there can't be a beginning of the universe and so on. And in fact that was just resolved later by a better understanding of continua so that there can be an infinite sequence of earlier times without the limit of that sequence it really existing. Now, whether that's how the universe really is. That's a matter for physics. But whether that makes sense. I think it does. And one needs a good theory of how things like that can make sense, which is matter for mathematics. So we shouldn't just throw away problems.

[B]

David, you've left out one entire field, which is the philosopher. Well, I don't want to interrupt, Lee, but I'm curious if people's idea of whether philosophers have a role to play in helping us define the.

[D]

Well, I think my response is the same as it was before. I think there are questions which are just not that interesting when you have a proper language. I think if you have a proper language for physics, you start with time and with. You start with a universe in which the world consists of nothing but events, and events happen. There are. There is a world before an event and a world after an event, and they're different. And that's a way that you make progress. I think that physics must make progress by focusing on what happened rather than what is. And sure, when you do that, sometimes you would make great discoveries, but sometimes you just reorient with direction your boat is going in, so to speak, and go somewhere where there's more to learn. And I certainly would never rule something out as a direction to go in, but I would rule things in. And I do worry when there is not enough variety in our searches, because I don't think we know what the right direction is to go in now.

[C]

Totally agree with that. Yeah.

[B]

So, Amanda, it seems that you don't just think that nothing is a reasonable thing to study, but rather an essential thing to study. Would you like to elaborate on that and on the context of nothing that should be studied?

[A]

Yeah, I mean, I think one way into it is to ask what is something? What's the other side of that coin that we're trying to talk about? I think one definition that I've come to from speaking to physicists is you can think of something being like a real thing, like an ultimately real piece of furniture of the universe. The real stuff of the universe is that which is invariant in every reference frame. So if you have something that from some perspective doesn't exist, then think of a mirage or a rainbow or something that's not like, it's not imaginary, but it's not the real, real stuff of the universe. And you can go back to. To Einstein taking space and time, which were thought to be these absolute scaffolding of the universe. And then he said, well, wait, actually, space and time are relative to your perspective. And it's this combined Four dimensional spacetime, that's like the invariant thing. And so the idea was, well, if you can find these invariants, the things that aren't observer dependent, then you have the something and then that's what you have to account for coming from the nothing. Right. And so what I think has been really fascinating is if you look at sort of the progress of physics from Einstein forward one by one, these things that seemed in classical physics to be absolute invariant, perspective independent things have turned out to be observer dependent, have turned out to somehow depend on your perspective. And, and that progression, and this was something that Wheeler thought a lot about, seems to open up the possibility that eventually what you're going to find is that the only real thing is nothing. And so, I mean, so that's a way in that's not purely philosophical. You can say, let's look at these things and say what is actually invariant and what is not. And, and so the vacuum, I was saying earlier, seems like something that should be invariant, but it's not. Space time, when you get into the holographic principle, seems not invariant in the way that Einstein thought.

[D]

So yeah, they may politely disagree.

[C]

Please.

[D]

What we've learned is that there are no absolute frames of reference. There are no Lorentz frames, there are no geometry of Lorentz frames. And when we look for those things, we find we have to throw them away and just go back to the only, the only observables are in the universe. And then you're only, as I agree, invariants under certain operations. But then we find, when we try to discover those invariants, we find that there, as you say, nothing. There's no invariant of string theory that can stand in the place of search for nothing. The holographic principle I think is a near miss and there's some truth in it, but I think it really doesn't work in the end. And general relativity, where you face a theorem, there's no killing field on the space of solutions of general relativity. And killing fields are connected to symmetries. And the statement that there are no symmetries in the solution space of general relativity is very important. It tells us that there are no such things as we're looking for to guide our way. And I think it's a very important thing to learn. And I think that theorem that there are no killing fields on this pace of solution for a closed universe shuts down a whole thing that many friends of mine and yours and so forth try to construct and end up failing to construct. And let's remember the holographic Principle, although it's not nice to talk against, only works for systems which have positive cosmological constant and positive vacuum energy. And we know from observation that our universe is not one of those. So again though there is appearance of triumph, actually that's that whole direction of thinking leading to what people call ADS CFT is actually failed if people just look at it correctly.

[B]

So look, Amanda, I'm so compelled by the very loose idea that, that you've started to present, but you did mention John Wheeler a couple of times and I guess alluding in part to his participatory universe in which he described reality as a self exciting circuit that can bootstrap itself from nothing. I guess in a sense. So I'm curious about your view. Is this also your sense of, of how reality can come from nothing? And also if such a thing can come from nothing, why couldn't there just have been straight up nothing at all? Why necessarily have a universe of somethings that emerges from this, I guess, cooperation of agents?

[A]

Yeah. So I mean Wheeler, I certainly can't do justice to his ideas in a quick summary, but he went through these different stages in his career of trying to build the universe out of different material, essentially. And so early on he said everything's particles. Then that didn't work out because particles are not observer independent enough, they're not invariant enough. Then he tried everything is space time. He wanted to use the topology of space time to kind of bootstrap charge and mass and all of these things. And eventually he thought spacetime can't be the fundamental ingredient that's not solid enough. And then he came to everything as information, which had a huge impact on the field of quantum information theory. And, but in his journals, what he kept agonizing over is whose information is my information the same as your information? That can't be guaranteed. What happens when we disagree? How do we piece that together into a shared universe? And so yeah, he came to this idea that the universe he believed is participatory in a fundamental way. And, but that wasn't fully resolved these questions about whose information? How do we piece together my information? Your information? But he had this quote in his journals where he said, this is very Wheeler phrasing. There is many a game we cannot play until we draw with chalk a line across the empty courtyard. It doesn't matter where we draw it, but only that we draw it. And so, right. This is the idea. You can think of the empty courtyard as nothing. The line creates a boundary that creates something. And what it creates is Something you can call observer, something you can call observed. And now you can define everything relative to everything else. But the whole mystery there, which is sort of what you're asking is like, is the drawing of the line, right? Is that chalk line? I mean, it's not meant to be something deeply real because, you know, it's chalk. It can be erased, it can be moved, but yet everything that we see seems to depend upon it in some way. And so, you know, I think the idea that he was groping toward was somehow everything seems to be defined relative to observers, to an observer's asking a question, it's participatory. It's not passive. The observer asks a question, the universe answers. And yet if you sort of take that line away, you're back to the nothing. In brief, I think that was his thought.

[B]

It's a beautiful image, and it is the idea that the universe is information. But whose makes me think, David, of your work in quantum information. I'm curious whether your notions of information are similar to Amanda's and John Wheeler's. If you can say more.

[C]

No, they're not the same. So John Wheeler was thinking of classical information and his attempt to understand. He understood that ultimately it has to be quantum. But all his attempts. How can I put this? 80% of Wheeler's agonizing was about trying to construct a single world in which Everett's multiple universes were not the true description of reality. And he got this compulsion from his. What do you call it? Mentor, Neil Spohr, who had a he. He was a brilliant, innovative thinker who contributed to the foundations of quantum theory when other people were still trying to hark back to classical physics. But he had a supernatural streak. He had a streak of sympathy for the supernatural and for obscurantism, which apparently infected all his mentees, including Wheeler and including Heisenberg. So you mentioned something earlier, or Lee mentioned Heisenberg. I've forgotten what it was, but whatever it was, it was because of Bohr. And so Bohr then attached himself to the stream of bad philosophy that was happening anyway in the 20th century and gave it the apparent imprimatur of fundamental physics. And that whole thing was a mistake. The whole participating universe and it from bit universe has information and. Observer participator and the lines across the courtyard, those are all copes for not wanting to accept Everett's quantum theory. Fortunately, the remaining 20% of Wheeler's musings were incredibly. Fruitful. So information in the universe is fundamental information, making the universe information being the thing that Makes the universe or is somehow outside the universal, before the universal, logically prior to the universe. That's wrong. That's just all this supernatural stuff. It's very important that the physical universe is such that information can exist in it. That is, information can be physically instantiated in it, never perfectly. And it's never the ultimate structure. We have computers that have got terabytes of information in them, but the physical structure is still silicon. And it was silicon even when our computers had only a few K of memory. Well, actually, even before that, it was probably. It was probably the vacuum, vacuum tubes. So there you had some kind of nothing that was. That was bearing information. So in a sense, serious.

[B]

So in a sense, we're talking about what is the substrate? Is the physical the substrate to information or information, the thing from which the physical emerges? Either way, both of them are not nothing. There's something first. So I want to move to theme three now, in which we try to think about whether thinking about nothing helps us to this biggest question of the bottom layer of the universe and so on. So I'll articulate it. Will the possibility of nothing help us understand the mysteries of the universe? Or should we look to the universe to tell us what nothing is? And perhaps we can move to Lee now.

[D]

Well, I just wanted to insert into the last discussion that I had the privilege once of being in a meeting with John Wheeler and Carlo Rovelli. This is years and years ago. And Carlo got John perfectly excited, enormously excited, by reading to him from his books of Heidegger. And John had never heard of Heidegger before this, but he certainly took off on what he understood Heidegger to be meaning. And I would agree with you 99%. I'd agree with David, But I should say that I have a 1% that wonders whether there is something in the European style of philosophy that there is something for us to learn there.

[C]

It shouldn't have anything out.

[D]

What.

[C]

One shouldn't rule anything out. So I agree. I keep the 1%. It might be useful even if it's false.

[B]

Lee, could you elaborate on what particular European style of philosophy or Heidelberg's statement?

[D]

It's been very hard for me to understand. I'm better at telling stories about my failures to understand it. Like, I had a very good friend who. Who was a feminist philosopher in New York, Drusilla Cornell. And she. She read my first really philosophical book, the book that became a joint book with Roberto Unger. And she said, there's somebody in our community who says the same things as you say, and it was Roberto Unger. And as a result, I met Roberto and we wrote this dual book together, which consists of a kind of exploration of our disagreements, which turned out to be an interesting thing to do. I don't know if anybody reads it that way, but that's the way you should read it. I'm caught between. Between wonder at trying to understand time in the sense of a creation of the world, a continuous creation of the world. I wrote my first book. I began with introduction, in which I. In which I quoted from Leibniz, and I quoted from Leibniz this beautiful passage in which he. He says, basically that the scientist trying to understand the world in all this, in all its enormous variety, is just like somebody in a city trying to understand the city that they live in in terms of the enormous variety of ways that you can be an observer and be what Amanda was calling who is observer? Who is observer? And Leibniz was celebrating the variety of observers in a city as a metaphor for what there may be in the world. And I think that there's an enormous. There's something enormously celebratory about the idea that the world is infinitely. Variety has infinite capacity to teach us and surprise us. And I think that's. That's very promising, especially at the moment. But it may be that our friends Galileo and so forth, Kepler, all these figures are tremendously paradoxical if you really read into them, because they are both celebrants of variety and explores a world with simple laws.

[B]

Amanda, nothing is central, it seems, to the way that you've talked about the universe and physics. Can nothing tell us about the universe, or can the universe tell us about nothing?

[D]

And how do we study nothing at all?

[A]

I honestly think it can go both ways. I think getting a good grip on what nothing is can help us understand the universe. But I also think things in the universe can help us understand nothing. I mean, an example that comes to mind, I remember having a conversation with Alan Guth, the cosmologist, about conserved quantities in nature. So one of the really fundamental things in physics is to look at, at what's conserved, the conservation laws. That's sort of the architecture of things. And what Guth was pointing out is, first, there were a lot of things in physics that people thought were conserved for a long time, like things like baryon, number of people thought were conserved, and then it turned out they're not conserved. But if you look at the things that are so, like, electric charge is conserved, energy is conserved, angular momentum is conserved, and then so Imagine, you know, you have a ton of angular momentum in the universe, or a ton of charge or a ton of energy. If that's really conserved, then that had to have been there from the very beginning. And that can't come out of nothing. So that impacts our understanding of, like, what are we trying to get out of nothing and how do you do it? And what Guth pointed out was actually, when you add up all take angular momentum, you know, the galaxies are spinning in different directions, and you add all of it up, it all cancels out to zero electric charge. The universe seems to be electrically neutral. It all adds up to zero energy. There seems like there's all this energy and mass in the universe. But he gave this whole explanation of how gravity actually has a negative contribution to that. And so it all perfectly balances out to zero. And so all of the conserved quantities turn out to the value is zero. That. That didn't have to be a fact. That's like an empirical thing the universe is telling us. And so I said to Guth, well, so are you saying as long as all these conserved values are zero, that means we can get something from nothing? And he said, maybe a better way of saying it is that something is nothing. And I think when Wheeler said that very cryptic thing to me about the boundary boundary is zero, I think he was trying to get at something very similar that when you look at the gauge theories, all the forces in physics he believed seemed to suggest that they're trying to conserve nothing. So I think you can go both ways. I think you can look at facts in the universe and say, well, wait a minute, maybe in some sense everything is nothing. I think you can start with the nothing and try to tell the story from there. And I think it's helpful to sort.

[B]

Of bounce between the two wonderful. Plus something minus something equals nothing.

[D]

Got it.

[B]

David, it's to you to bring us home today, if you can, a minute or two respond or give your last words on the matter.

[C]

Yeah, well, as I said, there's this ancient mistake of trying to find the bedrock on which everything can be built and from which everything can be understood. And I agree with, as always, as usual, with Karl Popper, who said that that's not where thinking should begin. We should always start with the problem, and the problem is never what the foundation is, because then there would still be the problem of why that foundation and not another foundation, and what does it really mean, and so on. And that leads nowhere, all to nothing. So we need. We have to start with the problem and what we're looking for when we're trying to solve a problem is, again, not the final answer. It is an explanation that tells us why the conflicts that we thought that we saw aren't really there, why some of the ideas that we thought were incontrovertible are not incontrovertible, and what can replace them, not because they are the final answer, but because they are a better answer than the one we had before. And that's all we can ever do. But that is a good thing, because that is the doorway, the open window, to an infinite progress.

[B]

I think. On that note, now that we have hope for infinite progress, I'm going to call the official part of the debate here. Thank you all.

[A]

Thank you for listening to Philosophy for Our Times. What did you think of this episode? And don't say nothing. Shout out to Eric, Manny and Matt, who reached out over the last couple of weeks about Arkahinda Andrews and Adam Phillips episodes. Your feedback was much appreciated. And if you want more talks, videos and articles from the world's leading thinkers, don't hesitate to go to IAI TV for thousands more talks. We'll be back next week with more groundbreaking philosophy. So see you then.

[C]

Bye bye.