376: How to Make Use of Our Limited Time in This Tiny Part of Space with Sean Carroll

“About one quadrillion years from now the last star will stop shining. Everything will fall into the black holes that are in the universe. And then those black holes will evaporate away. And 10^100 years from now, one googol years … the universe will be empty. And that, according to our best current theories, will last for infinity years. Will last forever.”

— Sean Carroll

During the pandemic, one thing we’ve had a little more of—at least sometimes—is time. Time to panic and stress and worry, but also time to think and reflect.

This week, in the spirit of reflection, we’re revisiting a conversation with theoretical physicist Sean Carroll recorded back in 2016. At the time he had just written a book called The Big Picture: On the Origins of Life, Meaning, and the Universe Itself, which explores questions about purpose and belief and meaning. Today, in 2022, his book is even more poignant. 

If you’ve ever found yourself feeling woefully insignificant relative to the vastness of space and time, Carroll’s perspective might just change your life. He argues that since we only have a limited time in a tiny part of space, we need to make good use of every heartbeat. 

The Big Picture is a poetic overview of the known universe, with deep insights into the human experience.

Note: This interview was first featured in episode 153 back in 2016.

Transcript

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You and Betty and the Nancy's and bills that Josie and James will find in the study of science a richer, more rewarding life is welcome to inquiring minds. I'm Indre Viskontas. This is a podcast that explores the space where science and society collide. We want to find out what's true. What's left to discover and why it matters more.

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And during the pandemic. Maybe one thing that we've had a little more of at least at times is time. Time to panic and stress and worry, but also maybe time to think. And reflect. This week, in the spirit of reflection, we're revisiting a conversation I had with theoretical physicist Sean Carroll back in 2016. At the time, he had just written a book called The Big Picture on the Origins of Life, Meaning and the Universe Itself, which explores questions about purpose and belief and meaning told through the voice of a thoughtful physicist.

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I still love that book. Today, the book and Sean's thoughts about it are even more poignant Welcome to Inquiring Minds. Sean Carroll. Thanks. Thanks, thanks for having me on. It's not often that we have a theoretical physicist on the show because there aren't that many of you around, and those that are around don't seem to be able to translate what you're doing in a way that I can understand at least.

00;01;38;20 - 00;01;54;28

Yeah, I think, you know, I'm a big believer in communication and outreach and so forth. But I think that it's every field has an obligation to reach out and explain what it's doing, but not every individual person and there's plenty of physicists that I know they love dearly and are great scientists, and I don't want them talking to the public.

00;01;54;28 - 00;02;10;24

So, yeah, I feel the same way about neuroscience. And and yet, you know, here I have a list of questions or topics more so that I want to talk to you about. And I feel like I really want to cover everything, even though we don't have time to cover everything. And, you know, you don't seem to shy away from that.

00;02;10;24 - 00;02;26;11

Your book is called The Big Picture. Is that essentially about everything? That's right. It is about everything. That's I tell people and they ask me what it's about. And I have written two other popular level books that were not about everything. They're about specific physics topics. So this is a big departure for me. I had to learn a bunch of things.

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And I'm certainly I'm not an expert on everything I'm writing about, but I saw myself with the idea that nobody is an expert on all of these things, and yet it is important to try to integrate them and see how they might fit together. And you talk a lot in the book about the importance of stories and that's kind of separate from how normally I think about theoretical physics, not that there aren't great stories there, but rather that sometimes I feel as if people's understandings of physics is about, you know, taking what is an amazing story and distilling it down to a single equation.

00;02;55;24 - 00;03;19;17

That's right. And I think that, you know, physicists and also some philosophers actually not only don't talk about stories, but actively react against the idea because they think of stories as something that connotes, you know, purposes that are imposed from the outside, a dramatic arc that gets you somewhere, you know, the hero succeeds or something like that. There's a telos, a point, a goal in the future.

00;03;19;17 - 00;03;43;25

And that is not what physics tells us the universe is like. So I use stories in the sense that there are different ways of talking about the physical world, theories of physics or biology or psychology are kind of story. Ethical principles are a kind of story. These are things that use different vocabularies, different protagonists, if you will, for the stories have different plots in different ways, and yet they can all capture some important aspect of reality.

00;03;44;08 - 00;04;07;06

You talk about a couple of major themes in the book. One of them is Time and that's something that, you know, I'm both fascinated by and petrified of. Another is emergent properties, right? And then you weave all of these together sort of under the umbrella of evolution and how this whole idea of of the evolution of time and how emergent properties come from that.

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And so in some ways, that's a really beautiful story. But before we delve into the details is there's something that our listeners need to know in terms of so that we can be all on the same page at the starting point. In this conversation. What is are the the key things that we need to know before we embark on this journey?

00;04;24;01 - 00;04;43;24

Yeah, I think there is sort of one sort of very basic element that is very helpful to keep in mind. Which is just that these different stories that we have, even at the simple scientific level where you're talking about different levels of description. So it's either physics or biology or neuroscience or whatever. The way that the world works can be very different at these different levels.

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And in particular something that we've known about for a long time and are still struggling to come to grips with is how time is different. It's not that the measurement of time is different. We can still measure what's going on, but in our everyday lives, the fact that time has a direction The fact there's a past that we came from are now in the present moment and are going toward the future.

00;05;04;24 - 00;05;33;18

That kind of idea is absolutely central to our everyday experience and yet nowhere to be found in the fundamental laws of physics. The fundamental laws of physics, as best we understand them, treat the past, present and future as completely equal There's nothing special about one direction or another. So one of the fundamental things, if you want to fit all these stories together, is to ask how the sort of impersonal timeless underlying laws of physics govern the world at one level.

00;05;33;26 - 00;05;57;11

And yet our everyday experience has this very strong directionality from past to present toward the future. And sometimes, you know, I feel like physicists say, well, that's just because that's only how your brain can process this passage of time. And yet it still seems as though the universe kind of has a trajectory in time. And this is where I struggle to make sense of it.

00;05;57;11 - 00;06;12;17

All right. So there was there a beginning? Is there was there, you know, good. Well, you know, a lot of these things, it's very easy to go to a point where the answer is we don't know whether the universe had a beginning or not, for example. We just don't know. The universe could be eternal. It could have had a beginning.

00;06;12;27 - 00;06;31;26

We know that 13.7 or 13.8 billion years ago something happened that we labeled the Big Bang. Right. It was a point where the universe was extremely hot and dense and rapidly expanding. That might have been the beginning. There might not be anything before that. But to be honest, we don't know. Our theories are just not good enough to extrapolate backward.

00;06;31;27 - 00;06;52;08

So there could have been something before the Big Bang. What we do know is that the conditions near the Big Bang from a physics point of view were very, very unusual in all the ways the universe could have been the particular way it was. Near the Big Bang is very, very special. It's very, very highly organized. It's what physicists call low entropy.

00;06;52;18 - 00;07;13;05

Entropy being the disorganization or disorderliness of the universe. And ever since then, there are many, many more ways for the universe to be high entropy than to be low entropy. So that's the direction in which it's been evolving. As the universe expands and cools the entropy goes up. And that's why you have this very, very strong feeling that there is a difference between past, present and future.

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It's ultimately that all of the different aspects, whether it's memory or aging or cause and effect, all of these can be traced to entropy increasing. And that can be traced to the fact that entropy was very low with the Big Bang. And is there going to be a time when entropy is going to be low again, or are we just going to increase out of existence?

00;07;34;11 - 00;07;55;04

Once again, we don't know. It's the short answer. We think we know we have a smart guess that that has a good chance, we think to be right, which is that entropy will never be low ever again. That we will sort of equilibrate. The universe will expand forever. In 1998 we discovered that the universe is accelerating, not only expanding, and we don't think that will ever end.

00;07;55;04 - 00;08;14;29

That's the simplest model anyway. So the stars will die out about 1 quadrillion years from now. The last star will stop shining everything will fall into the black holes that are in the universe, and then those black holes will evaporate away and tend to the 100 years from now. One Google years back before the search engine ruined the word.

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Google the number is ten to the 100 years from now the universe will be empty. And that, according to our best current theories, will last for infinity years. Will last forever. So where is all this stuff going to go? Well, the nice thing is that Albert Einstein told us that space can expand right the universe is not fixed.

00;08;35;03 - 00;08;58;22

So it goes far away. It expands away. The point is that in a universe that is accelerating, like ours is there's a horizon. It's sort of like being inside a black hole instead of outside. There's a there's a point instead of a point pass, which once you go, you can never return to the outside. There's a point that once things leave us, once things get far away, they can never come back.

00;08;59;03 - 00;09;16;13

And so ultimately, everything will leave us and we won't be there. I say us from the point of view of any one point in the universe. There will be literally nothing that he can possibly observe left except for empty space for billions of light years around So is there any chance that at that point there will be another big bang?

00;09;16;25 - 00;09;37;05

There's a chance right there. There's lots of chances because you don't really know what's going on. There's essentially no chance, or at least a very, very tiny chance that the whole universe will sort of collapse and undo all the progress of the Big Bang even if it did collapse. There's no reason to think that entropy would go down once again.

00;09;37;05 - 00;10;06;27

There's no reason to think that it would be the the time reverse of the Big Bang again, since we don't know what's going on, it's certainly possible people like Stephen Hawking have contemplated the idea, but there's no reason to think it. There's also the possibility that I am actually kind of fond of, which is that even though the universe itself just keeps expanding and stays empty, there can be little quantum fluctuations in tiny parts of the universe that can pinch off new baby universes that go their own way and start a life of their own.

00;10;07;16 - 00;10;30;04

So, in fact, our universe could have come from such a process I mean, we don't know why our early universe was so small, so tiny, and so low entropy. One possible explanation is that it came out of a preexisting spacetime that was just sort of sitting there quietly. So that means that at any given point, another little baby universe could be born.

00;10;30;04 - 00;10;49;13

That's right. It could happen. It's like in my living room. In your living room, there could be a big bang, like right here from a little baby universe. Well, that's the that's the interesting thing, is that it wouldn't look like a big bang to you. It would look like a small bang. So basically what would happen would be that the space in your room would pinch off a little wormhole.

00;10;49;23 - 00;11;07;05

And on the other side of the wormhole, there'd be a big bang. There'd be a little tiny packet of energy that grew into a universe. From your point of view, what it would look like is that a bunch of particles came together, made a black hole, and that black hole very quickly evaporated. And the energy that is released from that black hole evaporates.

00;11;07;06 - 00;11;28;24

It's comparable to a hand grenade going off in your room. So you don't want it to happen. On the other hand, the chances that will happen are extraordinarily, astronomically, infinitesimally tiny. Oh, okay. So if my hope was that I could live forever and it would be because I would be part of this next big bang that's not there a better hope to hang on to.

00;11;28;25 - 00;11;51;25

Yes. Would you put your hopes in biology? Not in cosmology, if you want to live forever. Yes. So. Well, that that brings me to another question, which is, of course, you know, we talk about the cosmos and the Big Bang and all of these multiple potential universes on this grand scale. But really what's meaningful to me is the 80 hopefully 100 years that I'm going to spend on this Earth which is an infinitesimal amount of time.

00;11;52;09 - 00;12;15;28

And, you know, very quickly, you start to feel as if what's the point, given that there's this massive universe? Yeah, I mean, the last chapter in my book is called 3 Billion Heartbeats, because the typical human lifespan measured in heartbeats is about 3 billion of them. And when you put it that way, it's honestly not that big a number like 3 billion is, you know, the kind of number we throw around in budget considerations all the time.

00;12;15;28 - 00;12;35;23

Right. So and that's it. If you if you believe the point of view that I take in the book, that the world is just the natural world, there's no extra world beyond that than what you personally are is not some ineffable substance that fills up your body that goes somewhere else when you die. What you are is a process.

00;12;35;23 - 00;12;53;16

Every living being is a set of chemical reactions interlocking and talking to each other. And when you die, those chemical reactions stop. They change into other chemical reactions that are not a living person anymore. So that's it. And, you know, a lot of people want to say, well, if that's it, then what's the point? What does it all mean?

00;12;53;17 - 00;13;14;27

You know, why should I care what happens in the world if I don't get to keep living forever? But my point of view is exactly the opposite. If you if you think that you get infinity years after you die, then who cares what happens here on Earth? Like this is nothing, right? But if you think that all you get are those 3 billion heartbeats, then what happens here to your life, to the people you know in the world you can affect?

00;13;15;02 - 00;13;41;17

That matters enormously. To me, And I actually think that that's an enormously important question for everyone to answer to themselves, because oftentimes I hear people justify what maybe would be questionable ethical behavior. And, you know, for example, discrimination against a group for their sexual orientation because they don't fit in with your religious beliefs. And your beliefs are that you are going for eternity, not for this particular life.

00;13;41;18 - 00;14;07;21

So, you know, even if you're on the wrong side of history today, you're still not going to change your moral stance on this particular issue because that's going to lead you to go to heaven. And yet, to me, I feel as if there's a there's a if if you believe, in fact, that this is all there is, there's a greater pressure on you to behave morally every minute of the day than for someone who has a belief in the afterlife, which is opposite of the argument that you often hear from people who have such religious beliefs.

00;14;07;22 - 00;14;30;08

Yeah. And it's an ancient argument. Right. I have this wonderful quote in the book from Tertullian, who was one of the church fathers and so he was, you know, a couple of hundred years after Jesus. And, you know, he was trying to make the argument against the Greek and Roman Atomistic You know, there's still the same argument, like, you know, the old atheists and the old religious people are still having the same argument that we had today.

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So he was picking on Epicurus, one of the Greek atomistic, because Epicurus said, you know, we're just atoms bumping into each other. When we die, we die. And Tertullian says people like that will never behave well because they're not afraid of hell. He's very, very explicit. Like, we Christians know that we better behave well, otherwise we're going to suffer eternal torment.

00;14;50;01 - 00;15;07;19

Otherwise, if you think that you only have a few years. What's wrong with being bad? It's only going to last for a few years anyway. But I think you're exactly right. You know, the opposite argument is just as strong. If you think that this is the only part of life that we have in front of us, then I think there's a very good argument to treating that part of life very carefully.

00;15;08;14 - 00;15;33;18

So as I learn more and more about neuroscience and the biology of the brain, I became more and more convinced that there really is no possible physical way that consciousness can exist outside of the biological body. And that kind of came at odds to the way that I was raised and my earlier beliefs. And there's a sort of sect of people who say, wait a minute, yes, that might be true from a biological perspective, but there's this whole quantum physics realm.

00;15;33;26 - 00;15;56;05

So maybe consciousness is on the quantum scale. And, you know, I never like to say, okay, let's explain something that we don't really understand. With something else we don't really understand. But now we actually are starting to understand quantum mechanics a little bit better. So I wanted to ask you to just talk a little bit about what kinds of quantum processes might be possible in our biological body.

00;15;56;12 - 00;16;19;06

And do those have any meaning for things like emergent properties, like consciousness? Right. I need to before you actually answered the actual question you asked, I need to put in a plug for Princess Elizabeth of Bohemia, who I mentioned in the book. I would like to make her much more famous than she already is. She had this ongoing correspondence with René Descartes, who famously had the idea of mind body dualism.

00;16;19;06 - 00;16;43;29

And Elizabeth just couldn't understand how you could have an immaterial soul or mind with no location in the physical world interact with your physical body. And the same problem exists today. Like, if you don't believe that the world is all just the physical stuff, if you believe there's something else in it, that means you must believe that this extra stuff, the spiritual aspect of your consciousness, needs to push around the atoms of which you are made and no one knows how that would happen.

00;16;44;00 - 00;17;06;00

So I think that Princess Elizabeth's critique is just as valid now as it was back then, though the loophole maybe that people like to appeal to is quantum mechanics because of what David Chalmers calls the law of conservation of mystery, that we don't understand consciousness and we don't understand quantum mechanics. So maybe they're the same thing right There's not he he says this as a joke because it's not a very good argument at all.

00;17;06;12 - 00;17;31;12

But it's true that we don't completely understand quantum mechanics, at least to the extent that physicists don't agree with each other about what quantum mechanics says. So even if I think that I understand it, no one else thinks that I understand it. So there's not a consensus there However, it is become very, very rare for working physicists to think that consciousness has anything to do with quantum mechanics.

00;17;31;19 - 00;17;55;13

There are some very notable exceptions to that. Roger Penrose is one example. And they become famous because they're the exceptions. Like they're the ones who are the iconoclasts. Penrose thinks that we need somehow to modify quantum mechanics to change it, to account for the fact that in his mind, human cognitive and human thinking powers are better than any artificial intelligence could possibly reach.

00;17;55;25 - 00;18;31;12

So people like Penrose try to rely on quantum mechanics to sort of give human beings better powers of thought. However, that does not come anywhere close to answering the sort of hard problem of consciousness about how we can have inner subjective experiences it just changes how our atoms behave. And there is zero observational evidence for it. Then there's also this idea it's a little bit fuzzy, but somehow that because quantum mechanics places an emphasis on observations, the real difference being quantum in classical physics is that to write down the rules of quantum mechanics, you have to give separate rules for what happens when you're looking at something and when you're not looking at it.

00;18;32;00 - 00;18;51;19

So that sounds like the conscious observer is playing a role somehow. But that's something where almost no physicists think that that is actually true anymore. Back in the 1930s, when they were still questioning about what quantum mechanics is, you could have very easily had that opinion in a respectable way. But these days we have equations that do the work.

00;18;51;19 - 00;19;09;22

We understand decoherence. We have models that are absolutely physical, that explain what happens during the measurement process. We don't have all the answers. We don't have the final formulation of quantum mechanics, but there is almost no reason to think that consciousness has any role whatsoever in explaining how quantum mechanics works.

00;19;20;09 - 00;19;41;26

So what about this whole uncertainty idea that that's sort of what I hear a lot of people talking about and not necessarily just in terms of consciousness. We can, you know, bring that lens out a little bit wider. And, you know, it seems as if the physical laws are very predictable and yet there's this whole uncertainty that seems to, you know, permeate everything.

00;19;41;26 - 00;20;04;00

And so. So how should we think about that? Yeah, the quantum mechanical version of uncertainty is related to this fact. That observation plays an important role in how we think about quantum mechanics. But from my perspective, it's sort of our fault it's not quantum mechanics is fault that this is a difficult thing. We think of the world, even the years after quantum mechanics was invented.

00;20;04;00 - 00;20;25;24

We still think of the world in the language of Isaac Newton in classical mechanics. Newton says there are objects, they have locations, they have velocities. And if you knew the laws of physics, given the locations and velocities, of everything, you could predict what happens next. Quantum mechanics says none of that is true. There are no such things as locations and velocities of objects.

00;20;26;02 - 00;20;52;04

There are quantum states. There are wave functions of objects. And when you observe the quantum state, you can observe something that looks like the Newtonian version of a location or velocity of something. But when you're not observing it, there is no such thing. Okay, so if you think that way, then quantum mechanics kind of makes sense. It's just a difference between what we what language we use to describe systems when we are and are not observing them.

00;20;52;09 - 00;21;12;27

But still, there's this deep seated human belief that it's the positions and velocities that are really there that really exist. So when we talk about uncertainty, the quantum mechanical prediction says that if you have a very good idea what the velocity will turn out to be in an observation, you don't have any good idea what the position is going to be and vice versa.

00;21;13;15 - 00;21;30;25

But the better way to think about it is just that there is no such thing as either position or velocity. There's just the wave function. And what you talking about is the probability of observational outcomes, not what really exists. So I struggled a lot through organic chemistry, and it was one of those subjects that I actually worked really hard on.

00;21;30;25 - 00;21;53;25

And finally, I feel like I grasped it towards the end. And then a whole bunch new particles were introduced. And yet, you know, are there any particles that we have recently discovered in the last ten years since I took organic chemistry or that we are about to discover that will really fundamentally change how we interact with the universe?

00;21;53;29 - 00;22;22;11

Well, I think the answer is no to a very good approximation. One of the claims I make in the book, which I think that particle physicists readily agree with, but it's not something that we sort of contemplate or talk about a lot, is the fact that the laws of physics underlying our everyday lives are completely understood. And when I say that people instantly want to ignore the fact that they said underlying our everyday lives and pretend that what I said is the laws of physics are completely understood and then point out that that is false.

00;22;22;21 - 00;22;39;28

But I need to point out that's not what I said. What I'm trying to say is that you and I and everything around us and sort of tables and chairs and planets and stars, these are made of particles. And we know what the particles are. They're made of electrons and then quarks and neutrinos and so forth. And we know how those particles interact.

00;22;39;28 - 00;23;03;18

We know the forces are that that interact with them. Now, we can very carefully, in the particle physics context, talk about a regime in which that way of talking about the world is adequate. We've done experiments to certain energies and at certain velocities and so forth. And as long as the reactions are at certain energies, low energies, basically this description works.

00;23;03;25 - 00;23;29;23

And that's what our everyday life includes. And we can even say that there are no more particles or forces of nature that could possibly have an influence over your everyday life. Because if they were strong enough and noticeable enough to have such an influence, we would have seen them in experiments already. So it's very very, very possible, in fact, overwhelmingly likely that there are new particles and forces that we haven't discovered yet.

00;23;30;16 - 00;23;52;17

But they are not the kinds that could possibly affect our biology or psychology or the stuff that we're walking on and seeing in our everyday experience. And yet, in fact, you call what what I don't know if this is your term or now an accepted physics term, the core theory as the greatest feat of intellectual human history or human intellectual history, I should say, So are we done?

00;23;53;00 - 00;24;12;14

No, we're not done. It's just the greatest feats so far. That's okay. We can do better in the future. The core theory is not an accepted label. It's Frank will check whose Nobel Prize winning physicist proposed the idea. Because what he's trying to get across is that we often when we do explain physics, we distinguish between particle physics and gravity.

00;24;12;16 - 00;24;31;07

You know, gravity is sort of the odd man out in terms of the forces of nature. We don't have a complete theory of quantum gravity in the same sense that we have complete theories of the other forces of nature. But what we'll check is trying to point out is that we have a perfectly good working theory of quantum gravity in our everyday lives, in that regime of the universe.

00;24;31;17 - 00;24;56;23

If you want to explain in terms of quantum gravity, how the Earth moves around the sun, we have no problems as long as you're not near a black hole or at the big bang. You can include gravity in the list of forces we do understand, even at the quantum level. So he proposed the term core theory to include both the standard model of particle physics theory of electrons and protons and so forth, and gravity in one quantum mechanical bundle.

00;24;57;01 - 00;25;20;21

That is the theory that underlies our everyday life. If you read the appendix of my book, I list all of the different things going on in the core theory in a very, very tiny font. Yes, I did notice that. And so do you think for someone if someone wants to be physics literate today, there's going to be good enough for them to understand the core theory, or is there something else that they should be paying attention to?

00;25;20;26 - 00;25;43;06

Well, I think, yeah, there's two things going on. One is that the word underlying is very important in the claim. The laws of physics underlying our everyday lives is completely understood Just because it's underlying doesn't mean that all of the manifestations of the core theory are completely understood. You know, some analogy sometimes uses that there's a difference between knowing the rules of chess and being good at playing chess, right?

00;25;43;18 - 00;26;07;17

We know the rules by which electrons and atomic nuclei interact. That doesn't mean we can predict the electrical conductivity of a certain material or something like that, much less the rate of chemical reactions in organic chemistry, for example. So even at the level of physics of the stuff we already understand, putting that stuff together into complicated macroscopic collections is not something we understand.

00;26;07;17 - 00;26;26;15

And there's plenty of room for doing better at that. But then also there is stuff that is just not everyday at all, right? There is the big bang. There is questions of the emergence of space and time themselves. There's dark matter and dark energy. So I'm making zero claims about how close we are to understanding all the physics.

00;26;26;24 - 00;26;46;27

We understand the basic rules by which the particles in you and me behave. So one of my hopes has been, Hey, if we understand physics a little bit better, maybe we can turn times arrow back words. Could we ever travel back in time? Is that even something that you think is remotely possible? And you know why or why not?

00;26;47;08 - 00;27;09;07

Well, we think that it is conceivable. It's the kind of thing that, in fact, I will confess, I have written papers in the science journals about the possibility of traveling backward in time. But my papers, like most other people's papers end up saying, no, it probably won't happen. If you if we had lived in a universe that Isaac Newton had described, where time and space were absolute we could give a more definitive answer.

00;27;09;07 - 00;27;26;23

We could just say, no, time is just one direction. And that's all it is. When Einstein comes along and says that space and time are curved and dynamical, that opens the door to maybe space and time are so curved that you could go visit the past, kind of like an interstellar. There's a wormhole that makes you travel through time as well as space.

00;27;27;10 - 00;27;46;07

But we think that in the real world, every attempt that we've had in our thought experiments to actually come up with a realistic version of this somehow fails one way or another. It seems as if the universe is conspiring to not let us travel backward in time. So that sounds a little religious to me. The universe is conspiring.

00;27;46;07 - 00;28;09;21

You know, there's an agent there. And also there's this just human tendency to try to seek the the answer to the question, why? Why is it this case? What, you know, what was the force that that began everything and so forth. So tell us a little bit about first of all, why do we keep coming back to this question of why and what does that mean in terms of how we understand the universe?

00;28;09;28 - 00;28;35;01

I think it's great to ask questions about why things happen one way rather than another. I think that what we need to appreciate is that there are limits on our ability to answer those questions, not just because we can't find out the answers, but literally because there might not be answers. I try to make the case in the book, maybe at overly lengthy discussions, that when you ask questions about why is this true, why is that true?

00;28;35;02 - 00;29;02;13

What is the reason for this This is something we're used to doing in our everyday lives. If a baseball comes through your window and smashes the window of your house, you think there's probably going to be kids outside playing baseball. If you look outside, right? Just baseballs don't just appear like that. But at a deep down level, the fundamental laws of physics, these kinds of issues of reasons why causes and effects once again, just like the arrow of time, there are nowhere to be found.

00;29;02;21 - 00;29;19;20

That is not the language that is spoken by fundamental physics. So when you want to know reasons why, it's always within a context of something. And when you ask, you know, why does the universe exist? What context is that supposed to be? I mean, was there a choice about whether or not the universe existed? Was it a 50 50 chance?

00;29;19;20 - 00;29;41;03

You know, these are not things that might have any sensible answers at all. So they might if maybe we're part of a multiverse and we can explain why our universe exists within that ensemble, but maybe not. So I'm all in favor of asking the questions. We just can't demand of the universe gives us a satisfying answer. And that's trying to sound a little bit like evolution and in particular, natural selection.

00;29;41;03 - 00;29;58;27

I always try to be very careful not to say, Oh, you know, we evolved consciousness because it allows us to, you know, think about the future, but rather, you know, to, to frame the question in terms of what are the selection pressures that might have influenced, you know, that particular trait, you know, to become more dominant in our species.

00;29;59;14 - 00;30;23;27

And so throughout your book, you actually, you know, talk a lot about these different scenarios or different different situations in which natural selection or evolution has played a role in our shaping. And in particular, I wanted to. And unless there's another a better example that that you want to talk about, the one that struck me was the fish that came out of the water and started to walk on land, you know, and you talk about it from like almost a physics perspective.

00;30;23;27 - 00;30;43;20

Like, what is the problem that the fish is trying to solve under water? It needs to think quickly. What about on land? Yeah, that's right. And I think that, you know, this is a for me, a situation where it's important to sort of do the philosophy. Right. When we talk about purposes and reasons why, sometimes that's okay. Sometimes it's not.

00;30;43;25 - 00;31;01;17

You have to be able to accept both those things at once. So I think that the emergence of higher level descriptions in the world, which has to do with the arrow of time and with evolution, does allow us to use words like purpose and reason why what the example I use in the book is. Is there a reason why giraffes have long necks?

00;31;01;20 - 00;31;20;07

You know, now you could say the reason why is because the initial conditions of the universe and the laws of physics led to drafts. Right. But that's a silly answer, right? That's hopelessly uninformative. It's much better to say something like the drafts are, you know, more successful. They have longer necks because they can reach leaves on the tops of the trees.

00;31;20;12 - 00;31;52;02

That's a perfectly legitimate explanation at that level of description. And with the fish climbing out on land, we were looking at the question of not we, but I was using work by Malcolm McIvor, who's an engineer at Northwestern University, who actually studies fish, but he's also philosophically trained, and he has some neuroscience background as well. So he wanted to know he he has this idea that maybe there are different steps along the way to the development of what we now call consciousness, self-awareness, the ability to imagine different things.

00;31;52;02 - 00;32;13;29

For example, and one such step might have been when the first fish came up on the land, they found themselves in a very different sensory environment. If the fish are swimming in water, the attenuation length of light in water is measured in meters. It's just not that far. So if you're swimming at a meter a second, once you see something you're almost on top of it.

00;32;14;04 - 00;32;34;00

The evolutionary pressure is to make a quick decision. This is a friend, is a foe, is this food? Whereas once you flop up on the land, now you're surrounded by air. Now you can see for kilometers. So you can see something that takes a long time to get to or to get to you. And now there's a new evolutionary pressure.

00;32;34;11 - 00;33;04;03

Can you use that time wisely? Can you think about different options? Can you use your imagination to make plans to contemplate hypothetical alternatives? And you can see how this would sort of move you in the direction of what we think of as consciousness. And in fact, neuroscientists have shown that when you are told when you put in an fMRI machine and told to imagine a situation in the future, the same part of your brain lights up as when you put in that MRI and asked who remembers something from the past?

00;33;04;11 - 00;33;30;19

It's a great example. Like there are many such examples of evolution repurposing some existing part of your brain that certainly doesn't explain all of human consciousness. But if you can imagine breaking down the evolution of consciousness into individual little steps like this. This particular faculty became useful in this particular evolutionary context. Several million years later. Here we are having podcasts and talking about the universe.

00;33;30;29 - 00;34;04;02

Yeah. Now that we can cook our food and, you know, keep away from everything, we have time to contemplate our place in the universe. I'm happy. Yes. So you framed this whole conversation within this term called poetic naturalism, which I really gravitated towards, pardon the pun. So tell us a little bit, what is poetic naturalism? Well, naturalism is the simple idea that there's only one world, the natural world, the whole multiverse counts as the natural world is basically distinguishing between a single world theory and saying that there's a spiritual realm or something like that.

00;34;04;03 - 00;34;26;22

So naturalism says that there's no such thing. It's just the stuff of the world that really exists that we can study by making observations. And then poetic is because even within naturalism, people disagree. And I think disagreement is good. We should all, you know, challenge each other. But there are very hard core mad dog naturalists who want to eliminate everything other than the fundamental stuff of reality.

00;34;27;02 - 00;34;47;25

They want to eliminate tables and chairs. They don't exist. They're illusions. What really exists are particles and forces at the fundamental level. And to me, that goes too far. I mean, if I can't say that tables and chairs exist, I don't think that's a useful way of talking about the world. But there are people on the other side who are sort of unsatisfied with the real physical world all by itself.

00;34;47;29 - 00;35;13;09

They want to add something to augment their naturalism, perhaps with objective moral reality or perhaps with mental properties that different pieces of matter can have that would help explain consciousness. And I think that's going too far the other way. I think that that sort of introducing extra things that we don't need. I think that that morality and consciousness and things like that are, like we said, different stories we can tell about the same underlying stuff.

00;35;13;20 - 00;35;43;22

So that's the poetic part of poetic naturalism, recognizing that there's one world, the natural world. But there are many ways of talking about it, many stories we can tell. So your book, it's called The Big Picture and the sort of sub subheading as on the origins of Life Meaning and the universe itself. You know, not, not, you know, but and you do know that we're all of these I need to notice that it's on those topics, but I do not actually tell you what the origin of life is, the origin of the universe or the meaning of life.

00;35;43;22 - 00;36;02;15

I talk about them. I'd say that there's a framework in which we can have that conversation, but you're not going to give the answers for me. But it's still a pretty comprehensive book, and there seems to be a lot of knowledge in here. And, you know, sometimes I hear people say we don't know anything about the brain. And that gets me really frustrated because, of course, yes, we know more than any one of us can ever truly understand in a deep way.

00;36;03;00 - 00;36;27;04

And I feel the same way about physics. We now know more than any one of us can really, truly understand in a deep way. So what are the questions still left that excite you? What do you hope to learn in the next ten, 15, 20 years? However, many heartbeats, hopefully of many more heart, many billions. Not. But but what are the some of the big questions that are, you know, get you up out of bed in the morning?

00;36;27;17 - 00;36;49;14

Well, I think that if the laws of physics underlying everyday life are understood, if the core theory is there, I still think there's wonderful directions to push in in sort of both directions, both sort of more fundamental and more emergent at the at the more emergent level. We know that entropy increases as time goes on, but the evolution of complexity is something we barely understand at all.

00;36;49;15 - 00;37;09;20

I talk in the book about some very preliminary work that leads me to believe that the that the coming into existence of complex structures as the universe evolves is a very natural thing, something you would expect. But we are not exactly able to say that there's some law of nature which says that complex structures necessarily forms. There are counterexample symbols.

00;37;09;29 - 00;37;32;10

So when does complexity come into existence? What is the right definition of complexity? What does it mean to say that something is complex and information processing and things like that think is wonderful? Questions to be answered there. And the other direction in the direction of becoming more fundamental. What underlies space and time itself is space itself emergent, for example, or fundamental.

00;37;32;20 - 00;37;49;04

Right now, in sort of the best established theories of physics we have, like the core theory space is just there. You know, it's given as part of the description. I want to know if space can arise out of something even more fundamental than that. How do you go about finding I mean, what is like a day in your lab?

00;37;49;04 - 00;38;12;08

Like, I mean, do you just you sit with a big cup of coffee and think or basically that said, the first thing to say is that I don't have a lab. I have an office and I have students and they have offices of their own. And we all have blackboards in our offices. So it's really, you know, the day to day work besides like the answering emails and traveling around, giving talks kind of stuff, the doing of theoretical physics research.

00;38;13;01 - 00;38;34;01

Yes. Sitting down with pencil and paper, pen and paper, blackboard chalk reading other people's papers, talking to your students, thinking about things, thinking, you know, we don't have that many clues about the emergence of space. For example, but we do have some we have some like things we know about black holes and the Big Bang thought experiments to a large extent.

00;38;34;01 - 00;38;52;10

But there's some information we have data about the Big Bang for example, and you want to put it all together. You want to say, like knowing the basic rules of quantum mechanics and understanding the clues we get from black holes that Steven Hawking has given us and so forth. How can we put this together to make a comprehensive theory that matches the world we see?

00;38;52;19 - 00;39;04;11

And you propose ideas, you write them down. People tell you that they're full of nonsense, and then it goes back and forth like that. Well, thank you for sharing some of your heartbeats with us and inquiring minds. My pleasure. Thank you for having me on.

00;39;07;29 - 00;39;38;08

So that's it for this episode. Thanks for listening. And if you want to hear more. Don't forget to subscribe. We've also revamped our website at Inquiring Show, where we're starting to build show notes about every episode, including links to the books and various other things about the show. That we find interesting. It's amazing to think that we've been doing this podcast for eight years now and have accumulated some 400 episodes So if you like what you just heard, there's a lot more.

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If you'd like to get an ad free version of this show, consider supporting us at Patriot Incom Slash Inquiring Minds I want to especially thank David. Noel Harrington. Shawn Johnson, Jordan Miller, Kyle Roy Halla, Michael Google. Eric Clarke, UC Lin, Clarke Lindgren, Joel Stefan Meyer, Eyal Dale Daly. Master and Charles While Inquiring Minds is produced by Adam Isaac.

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I'm your host Indre Viskontas. See you next time. There's more and so much more

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