309 | Christof Koch on Consciousness and Integrated Information

Consciousness is easier to possess than to define. One thing we can do is to look into the brain and see what lights up when conscious awareness is taking place. A complete understanding of this would be known as the "neural correlates of consciousness." Once we have that, we could hopefully make progress on developing a theoretical picture of what consciousness is and why it happens. Today's guest, Christof Koch, is a leader in the search for neural correlates and an advocate of a particular approach to consciousness, Integrated Information Theory https://en.wikipedia.org/wiki/Integrated_information_theory. Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/03/24/309-christof-koch-on-consciousness-and-integrated-information/ Support Mindscape on Patreon https://www.patreon.com/seanmcarroll. Christof Koch was awarded a Ph. D. from the Max Planck Institute for Biological Cybernetics. He is currently a Meritorious Investigator at the Allen Institute for Brain Science, where he was formerly president and chief scientist, and Chief Scientist at the Tiny Blue Dot Foundation https://www.tinybluedotfoundation.org/. He is the author of several books, most recently Then I Am Myself the World - What Consciousness Is and How to Expand It https://www.hachettebookgroup.com/titles/christof-koch/then-i-am-myself-the-world/9781541602816/?lens=basic-books. Web site https://christofkoch.com/ Allen Center web page https://alleninstitute.org/person/christof-koch/ Google Scholar publications https://scholar.google.com/citations?user=JYt9T_sAAAAJ&hl=en Amazon author page https://www.amazon.com/stores/Christof-Koch/author/B001IZVC1C?ref=ap_rdr&isDramIntegrated=true&shoppingPortalEnabled=true&ccs_id=573766f5-d54a-433a-98ea-075c00efa319 Wikipedia https://en.wikipedia.org/wiki/Christof_Koch

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

• 0:00Speaker 00

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• 0:58Sean Carroll?

  Hello, everyone. Welcome to the Mindscape Podcast. I'm your host, Sean Carroll. Despite multiple episodes here on Mindscape devoted to the topic, we have still not figured exactly out what consciousness is or how it works. We've had philosophers on, talking about what it means to have an experience. We've had neuroscientists, talking about what happens in the brain, all to no avail. It's not that there's not been progress. I'm slightly tongue-in-cheek here, but this is a hard problem. What exactly is consciousness? Because it's one of those things we're very, very familiar with, but it's kind of unique in that we're most familiar with it from the inside, right? Rather than, at an objective stance, measuring things with calipers or microscopes or whatever, we're experiencing it all the time.

• 1:43Sean Carroll?

  That's an opportunity, but it also creates certain, unique problems. So today, we're talking to someone who is a neuroscientist, but is also very, very willing to mix it up with the big philosophical questions. Christoph Koch is currently at the Allen Institute for Brain Science, where he was originally the chief scientist and president of the institute. Before that, he was a professor at Caltech for quite a while. In fact, I met Christoph when... Believe it or not, we were both consulting on a movie. And the idea of consciousness came up and the idea of consciousness in a computer came up. And Christoph pulls out his iPhone and points to it and says, how do you know this isn't conscious?

• 2:25Sean Carroll?

  At the time, I did not take that seriously, but now I understand the issue a lot better. And I know that he was gesturing toward the idea of panpsychism, which we've talked about before, of course, on the podcast. And Christoph is not quite a panpsychist, but he's panpsychist adjacent as a proponent of the IIT or Integrated Information Theory approach to consciousness. It's a very down-to-earth theory in the sense that there are numbers and equations, and you try to measure the connectivity and the integration of the information in some system. The system might be a human brain, or it might be an AI system, or it might be a pile of rocks on the beach. You can measure its integrated information. But the point is, you always get some number.

• 3:09Sean Carroll?

  And Christoph's point was, well, that number is not going to be zero for most systems. It might be very, very tiny, nothing like what we consider to be consciousness. But maybe you can talk about it as a wee tiny bit of consciousness, without actually saying that electrons have feelings. So this is years later, and a lot has happened. And we're going to talk about a number of things that Christoph has done. He's been very involved in figuring out, ever since his early work with Francis Crick, what are called the neural correlates of consciousness. So forgetting about what consciousness is, what is it that happens in the brain at the level of neurons when you're having conscious experiences? Doing very down-to-earth experiments in the brains of mice

• 3:51Sean Carroll?

  and seeing how maybe that can be extended to human experiences. And then developing tools to understand, is someone in a coma conscious? Is an artificial intelligence, large language model conscious? And so forth. His most recent book has the interesting title, "Then I Am Myself the World: What Consciousness Is and How to Expand It." So he's gotten into the questions of, you know, again, from the personal, first-person perspective, are there things we can do? Through meditation or other forms of enhanced awareness to improve our own personal level of consciousness. So Christoph is happy to be provocative about many things.

• 4:32Sean Carroll?

  We cover a lot of ground in a short conversation and I think you're going to find this one amusing. So let's go.

• 4:55Sean Carroll?

  Christoph Koch, welcome to the Mindscape Podcast.

• 4:58Speaker 03

  Thank you very much, Sean, for having me on Mindscape.

• 5:01Sean Carroll?

  You know, you've been doing this for a while, going back to your collaboration with Francis Crick after he moved from molecular biology to thinking about consciousness. I wanted to start by just asking, what is the major way, if there are any, that your views on what consciousness is and how it works have changed since you started thinking about this?

• 5:22Speaker 03

  Well, so when Francis and I started back when I was a young assistant professor at Caltech, partially overlapping with you,

• 5:33Speaker 03

  consciousness was still a complete no-no among serious working day scientists, particularly if, like me, you hadn't obtained the holy state of tenure yet, right? And so it was something that you did after hours and where grad students, you know, who are always in the know, they routinely roll their eyes when, oh yeah, that topic now, right? But that's, and then what we instituted, this purely empirical pragmatic program. Okay, let's forget about the philosophy because we haven't made much progress over the last two millennia there. Let's focus on what we can do. So we talked about certain model systems in monkeys, in people, of course, in mice, how to go about it, which techniques to use, which visual illusions to use, and what are some of the basic questions?

• 6:16Speaker 03

  And that really caught on, this purely empirical program, and led to what's now known the search for the NCC or the neuronal or the neural correlates of consciousness. In other words, what are the footprints in the brain for anyone? Conscious experience like right now I see you and I hear you in my head this voice inside my head well Nothing in physics right now tells us why there should be voices or sights or smells or feeling of being angry upset in love right Nothing in quantum mechanics, nothing in general relativity, nothing in periodic table of chemistry, nothing in the endless ATGC chatter tells me That we have these things, these voices, these experiences. And so the the search for the NCCs is

• 7:01Speaker 03

  Neutral with respect to your particular philosophical metaphysical underpinning. As long as you believe and not even all philosophers believe That consciousness is something that needs to be explained. Some philosophers, most famously Dan Dennett and and the Churchlands, they claim it's all a big confusion. It doesn't really exist in any in any sort of way that you and I believe it exists and Um it's just a big distraction. But for among the vast majority of people and even the majority of philosophers, It cries out for an explanation. Looking for the footprint is an empirical program. Yeah. However, and and and this is also what what has changed since I worked for with Francis Crick for fourteen years.

• 7:43Speaker 03

  Let's say in the fullness of time, we will have an explanation about the neuronal footprint. So Anytime Sean that you feel bored, the feeling, the experience of being bored, it feels like something to be bored, right? Very different from being in love. We know ultimately we will know it involves these neurons or maybe that mechanism or maybe even the collapse of the of the of the wave function. Okay, whatever it is. But then, of course, you want to know, well, What why this mechanism and not that? Why these neurons here and not those neurons? If it's a collapse, why should the collapse feel like anything, right? So so this is of course also known as the as a hard problem

• 8:22Speaker 03

  Uh by David Chalmers. So ultimately, we need a theory of consciousness that precisely gets at the question you asked earlier on. You warned me you you're gonna ask when is a fetus conscious and if so, when? Is a machine ever conscious? Is a particle ever conscious? Is a parametrium ever conscious? For all of that, you need a theory of consciousness. You need an empirical, verifiable, scientific, objective theory that tells us which bits and pieces of matter, which bits, pieces of organs like this, the most complex piece of matter in the known universe, have feelings. And, and Francis and I, we, we purposely didn't go there. But that of course was, was, you know, thirty years ago. And so in the meantime, we have theories, in particular,

• 9:07Speaker 03

  one, one of the two most popular theories, integrated information theory of consciousness, that Francis would have liked because it's causal. And in fact, he met the, the, the, the originator, Giulio Tononi, we had lunch. He came over twice to have lunch with Francis and I, and myself at his house.

• 9:27Speaker 03

  That, yeah, so that's the biggest difference.

• 9:29Sean Carroll?

  So we want to-

• 9:30Speaker 03

  And perhaps the metaphysical assumptions, but we can leave that for later.

• 9:33Sean Carroll?

  We, we might get there. But, so in other words, you, from the start, were looking for the things that happen in the brain that correlate with the conscious experience. Now you're more taken with the idea that that's important, but also we need a theory so that we can ask about things we can't immediately quiz, like, like the fetus or the AI.

• 9:56Speaker 03

  Yeah, exactly. We're, we're right now completely dependent on our intu-, our intuitions, our religious or philosophical biases, right? For some people, of course, the fetus is conscious, right? Way back to inception. Other people say, no, it's only born, only when it's born to, you know, is a dog conscious? I know you're a cat lover, are cats conscious? How, how, how far does consciousness go down the tree of life? All of that, right now, we have intuition. Everyone has a, has a different intuition. But that's not good enough, right?

• 10:28Sean Carroll?

  Yeah.

• 10:28Speaker 03

  We all have the intuition that whale, whales are fishes. Well, it turns out actually they're, they're not fish, they're mammals.

• 10:35Sean Carroll?

  Well, you mentioned the idea that you're talking to me, you're seeing a little picture of me, you're hearing what I say. What, what is the distinction between consciousness, which seems so laden and philosophical with simple awareness of things? Are they the same thing?

• 10:51Speaker 03

  Yeah, so for us, so Francis and I wrote about it explicitly. For us, they're just different words. Some people, particularly early on, now you can use consciousness even in nature and, you know, in PIL. You couldn't do that thirty years ago, unless maybe you're a Roger Penrose. So people use this softer thing, awareness. Awareness is just a more generalized sort of, you know, you're aware that you're alive, you're aware that you're awake, you're aware of, you know, that, that, you know, there's a precedent here. So it's more background consciousness. But it's all about, ultimately, you can also call it mental states, subjective states, phenomenal, you know, philosophers like to use the word

• 11:32Speaker 03

  phenomenal. It's all the same. This, it feels like something to be alive, to be awake, to be bored, to be hungry.

• 11:41Sean Carroll?

  And how much progress have we made on the literal neural correlates? Do we know which little neurons are firing when I'm hungry? When I'm feeling the feeling of being hungry?

• 11:52Speaker 03

  Well, even if we knew, of course, we know a lot about neurons and we know a lot about brain areas, but those are, of course, all correlation. Yeah, so we know, we know, I mean, there are hundreds of experiments. Right now, I see you and you see me. So we have a pretty good understanding what are the neural pathways involved in vision. Vision, because it's the best studied modality of all. But of course, that's different from, that's just correlation. Which of those bits and pieces are actually necessary? So for instance, the eye, clearly, you know, photons are entering my eye and then are transformed ultimately into vision. Do I need my eyes? No, I can close my eyes and I can see you still, ghostly. And of course, tonight, if I dream about you, you know, I dream in

• 12:35Speaker 03

  the dark and my eyes are closed. So I don't need the eyes. So, so the, the challenge has been to, to sort of disambiguate me a correlation from what is actually the causal agent. And there, it's still very controversial. You, you may have heard, I had this famous bet with the philosopher Dave Chalmers, twenty-seven years ago now, where after a late night pub call in Bremen at a conference on consciousness, you know, he challenged me, he says, look, even in a quarter of a century, which, you know, I was, we were all much younger, seen forever. We won't, we won't find these. It'll, it's gonna take us much longer. He didn't say it's impossible.

• 13:15Speaker 03

  He agrees the N C C is a purely empirical, operational defined project with enough people, money, funding, research. We will figure it out. And so we had this meeting two years ago where it turned out as part of this adversarial collaboration, so the Templeton Foundation started this cool project where they put, where they pitted the two dominant theories of consciousness, integrated information theory and global neuronal workspace theory directly against each other, where a little bit like, you know, the, the, the famous experiments nineteen nineteen, you know, predicting, you know, the, the solar eclipse, during the solar eclipse, whether the, the shift of life follows Newton, Newtonian physics or Einstein general relativity.

• 14:00Speaker 03

  We directly pit the two theories against each other trying to resolve empirically, well, where is it? What are the empirical predictions? Which one is actually true? And, and so at this meeting in, in, in New York in May of twenty twenty three, the agreement was, well, none of the theories are totally correct, at least the empirical manifestation of these theories in the brain with respect to where is the neural correlate? So I A T says neural correlate is in the back, the sensory cortices. Well, global neuronal workspace make the argument it's primarily in the prefrontal cortex, a part of the brain that's most expanded in, in, in humans compared to other mammals.

• 14:45Speaker 03

  And the field still hasn't settled down on that. That paper is finally coming out in Nature in a couple of months from now. Okay. Because there was a lot of controversy about it. It turns out, big surprise here, Sean, it turns out people who worked for twenty years on a theory, then if you go into this adversarial collaboration and the theory or somewhere its prediction is disproven, they don't just say, ah, you got me, my theory is wrong. I admit 25 years of my life was wasted.

• 15:14Sean Carroll?

  What?

• 15:14Speaker 03

  Sorry about that.

• 15:14Sean Carroll?

  I don't believe it.

• 15:16Speaker 03

  Yes, people actually don't do that. Surprise, surprise. Newton wasn't around in 1917, 1919. Otherwise, he would have objected again. Right? So, um, so, so we still haven't converged, but we're getting closer. And what we do realize in what came out in this debate, that the prefrontal cortex, and this is relevant to your other question, are computers ever going to be conscious? Is much more closely associated with doing, with planning, with intelligence. Right? This is the difference between consciousness and, and intelligence, right? So, and also artificial consciousness, artificial intelligence.

• 15:57Speaker 03

  Consciousness is ultimately about do, about being, being in love, being happy, being angry, seeing things, hearing things, et cetera. While intelligence is really about short-term, medium-term, long-term planning to act, right? I have to save money now in order to collect it at retirement, right? That's an intelligent action. So ultimately, that's about doing stuff, function, it's about functions, et cetera. And that's different from, from, from, you know, being. And so therefore, it's not that surprising that the parts and bits of the brain that are involved in planning and reasoning, in, in thinking, in moral reasoning, in decision-making,

• 16:39Speaker 03

  are different from the bits and pieces of the brain that seem to be the substrate for feeling, for having experiences.

• 16:45Speaker 04

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• 17:46Sean Carroll?

  Well, I love the idea of the adversarial collaboration. I think it should be more widely adopted, although some adversaries would just not be able to collaborate, in my experience. So congratulations to you, folks, for being able to do that. But now I need to ask this question, even if it takes a long time to answer. What are these two theories? What is integrated information theory, global workspace theory? I had never heard the idea that they focus or they propose different parts of the brain as being central for consciousness.

• 18:17Speaker 03

  Well, I mean, that was a good thing that came out of this meeting. Well, let's step back. Most people, in fact, I just attended just before a meeting at Google, I mean, virtual, at DeepMind in London, about what's called computational functionalism and consciousness. So most people who study consciousness, particularly everyone in AI, in big tech, makes this philosophical, metaphysical assumption that was proposed formally by Patnaam, the American philosopher, called Turing functionalism or computational functionalism. I consciousness has one or more functions. Let's call it planning or summarizing the current state of the world in my mind and

• 19:02Speaker 03

  acting on it, you know, long-term memory, broadcasting information in the brain, probably a list of functions. And any system that implements these functions will therefore be conscious, including a Turing machine. So if we can get a Turing machine to mimic everything that people do that seems to involve consciousness, like talking about consciousness and reasoning based on it, then machines, like large language models, will also be conscious. And so now it's just a practical question we can discuss is, you know, chat G P T uh four point O is O three,

• 19:41Speaker 03

  you know, is Deep Seek, uh is Gemini, are they conscious or they still missing? Well, maybe they're still missing a little bit of something, you know, maybe they have to take in more tokens or to do a little bit more longer memory or whatever. But it's really just a question around pragmatics. So that's computational functionalism. So any system, so ultimately consciousness is a computation, it's a hack. If I if I program machine, it's substrate independent, it can run in the cloud, it can run on a quantum computer, whatever. It's a clever hack. And once you instantiate this hack, of course, these machines are conscious, you can ask them. And they talk about it at a great length, how conscious they are, how they feel, right? Versus.

• 20:22Sean Carroll?

  That's sorry, that's according to that view, the Putnam view.

• 20:25Speaker 03

  Uh, the Putnam view, which is very, very prevalent. And of course, it is the dominant one in the um in the industry. And I get it's so dominant because if you interact with an L L M, they seem incredible, not only intelligent, but also, yeah, they they talk about feelings.

• 20:41Sean Carroll?

  Aware, yeah.

• 20:43Speaker 03

  Now, of course, they talk about feelings because they've been fed on every novels humans have ever written. And all novels are about the feelings of the protagonist, right? Their love and hate and being slighted and being insulted and hurting and et cetera, et cetera. And they've ingested all of that like vampires. So of course they can reproduce it. It's all deep fake. That's what I believe. Okay. So the other theory on the other side, there's really only one dominant theory, which is integrated information theory, which says, no, consciousness is not a clever hack. It's not a computation, it's not a process, it's not a function, although it may be associated with all those things.

• 21:21Speaker 03

  Ultimately, consciousness is, as I said, a state of being, it's a structure in a very high dimensional causal space. So ultimately. Consciousness is about a system, a substrate like this brain, having causal power upon itself. And this is the particular way the system acts upon itself. In other words, can determine its own future and be determined by its past. I can, I can unpack that. The more this system feels like something. So it's a little bit like saying complex systems that can act upon themselves. In other words, that are not just randomly determined where the next state is a function of the previous state.

• 22:01Speaker 03

  Any, any such system, if you look at the, the, the mathematical formulation in terms of its transition probability metrics, has what's called causal power. The current state co-determines the next state. There may be some noise, so it may not be fully deterministic, but determines the next state. Or the past determines the present and the present determines the future. The more power this, the more internal causal power this system has to, to determine its own fate, the more it is conscious. And the theory describes two aspects of it. Eight, it has a, a number called phi, the Greek number phi, which you can also think about the irreducibility of the system.

• 22:45Speaker 03

  The more the system is above and beyond the sum of its parts, the more, the higher the phi, the more it is conscious. So you can have a system that's phi zero, which means it's totally, it is, it does not exist as a whole. Its reducibility is, um, its, its irreducibility is zero. It's not really a system. It's more two independent system. That system wouldn't be conscious. The higher the phi, the more conscious the system is. And most importantly, and this is never stressed by other theories, it, you also have to have a theory that tells you why does being in love feel the particular way it does?

• 23:27Speaker 03

  Why does time flow? You know, we all experience time as flowing forward and never move backward. Why? Space, you know, whether it's visual space or seen space or heard space feels extended. Well, what is it about the underlying substrate that gives rise to the feeling of extendedness or boredness or, you know, being bored or being angry? So the theory also explains by the structure of this unfolded causal space, why one experience feels the way it is very different from any other experience.

• 24:01Sean Carroll?

  And so the, is the global workspace theory the sort of descendant of the functionalism of Putnam?

• 24:07Speaker 03

  Yeah, okay. Sorry, you asked me that. Yeah, so global workspace is a computer science metaphor from the, from the 50s, right? The idea is you have a central process and that writes information on a, on a, on a blackboard. It's also called the blackboard architecture. And then every local processes can access this, this blackboard. So the idea here is my brain does many things, but unconsciously. Like you and I, like all humans, we move our eyes four times a second. Okay, the regulation of eye movements is very sophisticated, highly controlled, but it totally bypasses our consciousness.

• 24:48Speaker 03

  Just like the way I adjust my gait, I move my hands, I sort of infer syntax, right? We speak in correct sentences, but we, we don't consciously put those things together. It just happens. Those are all local process. Every information that's conscious is globally accessible. What's meant, and I think it's a correct insight from psychologists, once I'm conscious of something, oh, there is something funny over there. Then my, then all the different processes in my brain, I inform about it. I can put it into long-term memory. I of course have it into short-term, short-term memory. I can use that, that information I'm just became conscious of to do long-term planning. I can think about it. I can reason about it.

• 25:33Speaker 03

  So that's the idea that once information becomes global, it's accessible to the, to all the information processing system in the brain. And that's what consciousness is. So the metaphor is really you broadcast information. And, and, and, and Stan Hahn and his collaborators.

• 25:54Speaker 03

  Have identified a set of neurons that that are situated in the prefrontal cortex that project their information back to the rest of the brain. So that is this broadcast. So the claim is every time information percolates from, let's say, from the visual system that that starts at the back of your brain, propagates forward, is still local, is still local, then reaches the front of the brain. And then that information, if it's important enough and we attend to it, becomes, is broadcast to the, to the, all the rest of cortex, to the neocortex, the outermost layer of the brain. That act of broadcasting, that function is what constitutes consciousness.

• 26:34Speaker 03

  So any system that instantiates that, that broadcasts will be conscious.

• 26:41Sean Carroll?

  So if I understand it correctly, then the global workspace theory seems to focus on the spotlight of attention that consciousness involves, whereas integrated information theory, IIT, is more about this sort of, well, the integrated information that we use to plan and control our own destinies.

• 26:59Speaker 03

  Yeah, but it's not just destiny at a high level, you know, at a high level, it's just looking out in, I mean, causal power is just the ability of, of, you know, let's see, some elements, whether neurons or transistors or whatever, to influence, for electric charges has, has extrinsic causal power, right? Because a positive charge here has the ability to influence the negative charge over here. Gravity has causal power, right? Due to curvature in space-time. So those are examples of extrinsic causal power. Intrinsic causal power is just, you have a, you have a little cellular network of neurons or cells or, or transistors, whatever. And if they, if the neuro or these elements are in this state, then the next state will

• 27:44Speaker 03

  be this. And if they're in that state, then the next state will be something else. So, so causal power is something you can actually evaluate if you have a complete this mathematical description of a system, how, how its states evolve over time and how the individual elements influence each other, you can fully compute, explicitly compute all of its causal powers.

• 28:07Speaker 03

  And it's not a airy-ferry, it's an operational. So in that sense, it's very operational. It doesn't appeal to anything mysterious. So it's not dualist. Some people say IT is dualist. Well, it's not because it doesn't appeal to any, to any substance. It's just the claim that fundamentally what experience feels like is this unfolded causal power. So any system that is integrated, that's more than the sum of the individual parts, maybe even a very simple system like a parametrium, will because of its vast complexity of the, you know, in a parametrium, there are probably a billion different molecules of maybe a thousand or 2,000 different types, you know, proteins, et cetera. They all interact causally with each other.

• 28:49Speaker 03

  And this causal interaction feels itsy bitsy like something, like being alive, maybe.

• 28:55Sean Carroll?

  So this is why you are not, you know, running in fear from the idea of panpsychism, even though you're not like a full panpsychist, but you, you kind of get why that would be a way of thinking about things. Consciousness is not something that pops up at a threshold. It's like there's little bits of it everywhere.

• 29:15Speaker 03

  That's correct. I mean, that's entirely correct. It's also parameter free, right? You don't have to say, well, if your phi is 42, then you're conscious. But if below 42, sorry, you just didn't make it. Because that seems totally arbitrary. What, I mean, why 42? And particularly if you're, if you're, so, you know, I'm also a biologist. So we study mouse brains that are, you know, tiny fraction, the size of, of human brain. In fact, almost exactly a thousand times. Yet if you look at the, at the hardware, it's almost impossible, you know, if, if I focus in with, with a microscope on a tiny, you know, kino size grain of, of mouse cortex, it's almost impossible to tell it apart from, from the human brain.

• 30:00Speaker 03

  And so there's no doubt, you can go even down to smaller animals, that if you just observe animals, they have complex behavior, they have memory, that is quite likely that all animals, certainly animalia, may well feel like something. And this is of course, this very ancient intuition of, that's called panpsychism.

• 30:21Sean Carroll?

  But you would, you would, I should phrase this as a question. Would you classify yourself as a physicalist? Do you think that it's just physical stuff? There's no spooky essences involved here?

• 30:33Speaker 03

  Well, so something that's always bothered me about physicalism from way, way back is the mental is clearly not physical. My state of seeing, of being, of thinking, or whatever, is not, is, is, is not physical. By definition, it's phenomenal. In fact, Schrödinger, so I was recently rereading Erwin Schrödinger, right? And he mixes, he mixes very explicit that as, even as a physicist, I have to look, I have to experience the trace of an, on an oscilloscope. What it means, I have to see, that's a conscious experience. I have to hear other people saying something.

• 31:16Speaker 03

  When, when, you know, when like Einstein, I'm imagining some, you know, the elevator and free fall, et cetera, well, I use my imagination, that's consciousness. So we cannot escape everything we have. The only thing, Sean, we have access to, the only thing is our experiences of the world. I don't have access to atoms. I never had, no one has. Yeah, you can show me little pictures, you can show me equations that are compatible with atomism and all of that, but you don't have direct access. All you have access to is the phenomena, all these beautiful shapes painted on the inside of your cage that you call your reality, that's your bespoke reality, right? That's the only thing everyone knows of.

• 32:00Speaker 03

  We, that's the only thing philosopher have the phrase, you are directly acquainted with. So physicalism is an additional assumption that says, well, there's not only this physi, this, this, these phenomena, but then I infer there's something above and beyond. So now inverting that and saying, well, now I'm gonna do away with this observer altogether, right? So there are no phenomena, everything is physical, it's always struck me as ludicrous. But until recently, you couldn't say that in polite academic society if you wanted to remain a scientist, okay? You can't say that because then people say, oh, now we're talking about woo-woo, right?

• 32:36Sean Carroll?

  Yep, I would say that, but that's, I'm glad you're liberated. I'm glad that you feel the courage to admit these inclinations.

• 32:43Speaker 03

  Yes, in fact, I have, after a particular type of experience I had, I became re-acquainted. So I grew up obviously in a Germanic household. And I grew up around not only Richard Wagner, but also Arthur Schopenhauer, who is probably one of the best known, at least modern western idealists. And now there is a resurgence in philosophy, not only in perp-psychism, it's becoming more popular now, but idealism, good old idealism. And so I'm thinking of this computer scientist, I think I would warmly recommend your interview, a very smart guy, computer scientist and philosopher, he has two PhDs, Bernardo Castrop,

• 33:26Speaker 03

  who has this, he calls it analytic idealism, which is really sort of Schopenhauer for the modern world, where essentially he says, "Well, the simplest explanation, we can all agree following Occam's razor and all of that, the simplest explanation, if we only postulate one thing, well, the only thing I've directly acquaintance with is phenomenal. It's phenomenal all the way to the horizon, because that's the only thing I or you ever know. So then everything is phenomenal. And in fact, the physical has to be explained within, it's ultimately arising from the phenomenal, that even the physical stuff like atoms and charges and elementary particles and quarks and whatever you have,

• 34:09Speaker 03

  ultimately has to be explained with respect to the phenomenal. And then this philosophy now meets foundational physics, where you know, ever since Bell's inequality and the entangled particles and Einstein's spooky action at a distance, we now know there may be no truly observer-independent events. And then maybe the observer has to be right there, central part of physics, including maybe saying, "Well, that's really fundamentally what truly exists." Because here's one point, Sean, which is really central to IIT.

• 34:50Speaker 03

  I A T distinguishes between absolute existence and relative existence. Absolute existence is existence for itself. You exist for yourself. Tonight, when you're gonna go to sleep, three hours earlier than I am, you will, particularly in the early phase of your night, of your sleep, you'll go into deep sleep. So if I wake you during your deep sleep and I ask you, Sean, Sean, wake up. Where did you just come from? You would say, typically, you would say, from nowhere, because you were deep sleep. You know, these delta waves are crisscrossing your brain. You were not there. You were not there to yourself. Your partner, your, your, your, your, you know, your bad partner can definitely see your body is there. So you're there for others, but not for yourself.

• 35:35Speaker 03

  Then later on, as you continue to, as your body continues to sleep, you'll wake up inside your sleeping body and suddenly you are something. You are, you know, flying, you're meeting long-lost, you know, dead friends, lovers, pets, whatever, you're dreaming, it's a conscious state. And so this cup only exists for others. This cup does not exist for itself. Only conscious creatures, only conscious system exists for themselves. So that's really the fundamental gap that runs straight through everything. Are you on this, do you exist for yourself or do you only exist for others? That's the, you can see, that is the most critical distinction there is.

• 36:17Speaker 03

  And so that really puts the onriss on the phenomenal, on experience.

• 36:21Speaker 00

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• 36:50Sean Carroll?

  This is great. It's wild stuff. I'm very glad you're saying it. I could not possibly disagree more with everything that you're saying, but I love it.

• 36:58Speaker 03

  Wait, wait, wait, wait, okay, why, why?

• 37:02Sean Carroll?

  I don't.

• 37:03Speaker 03

  What do you disagree?

• 37:04Sean Carroll?

  I'm a physicalist through and through. I think that quantum mechanics doesn't say what you say it says. I think that as scientists, we take in data from the world, from the phenomenal experiences that we have. That's absolutely true. Completely agree with everything you say, that of course, we, by construction, we get what we get as our phenomenal selves by construction. But then we use that to make a hypothesis about how the world works. And the best hypothesis we have is the true existence of a physical world, of which we are emergent parts.

• 37:34Speaker 03

  Okay, so I like, I've no trouble with the hypothesis. That's of course what I do every day in my daily work, you know, studying brains. But I guess we can differ to what extent quantum mechanics now reintroduces the notion of, or is thinking of getting rid, you know, there was this paper in Nature Physics a year ago by Howard Wiesmann and people from Australia, right, questioning the absolute, the absoluteness of events, that every, every event, that facts, there are no observer independent facts. No, I

• 38:18Speaker 03

  agree that hasn't been resolved, you know, it's ongoing. But that's always been a challenge for quantum mechanics to see what is a fact and what, what, what facts do not depend on an observer?

• 38:30Sean Carroll?

  Well, I think that this is one of the difficulties in understanding quantum mechanics, because it's the one theory that we have in physics, putting aside consciousness and psychology, et cetera. But in physics, quantum mechanics is the one theory that introduces the notion of an observer when it gives you the rules of the game, right? I just wrote my own paper in Nature that appeared a week ago, you know, sort of rehearsing the history of this. I'll send it to you. But

• 38:57Speaker 03

  Oh, yes, please.

• 38:58Sean Carroll?

  But of course. There are, since the 1950s, straightforwardly physicalist models that explain why observations in quantum mechanics seem to be special without making observers a part of the fundamental ontology. And then it's an empirical question if and which of these models are actually correct.

• 39:22Speaker 03

  I agree. Ultimately, it's an empirical que-- well, the metaphysics, of course, for better or for worse, is immune from verification or falsification, right? The metaphysical interpretation, yes. Ultimately, it's an empirical question, does, you know, what is the best theory within? Is it a psi-ontic theory, a Bayesian theory, or many-world theory, et cetera, within quantum mechanics? Yes, I totally agree.

• 39:51Sean Carroll?

  Yeah, I mean, my inclination, and I'll try not to go on too long, because this will-- because there's so much good stuff I want to talk about, so otherwise, we should have a whole separate conversation. But my impression is that assuming physicalism and deriving mentality from it is enormously more productive scientifically than biting the bullet of idealism and trying to derive the physical world from that.

• 40:17Speaker 03

  I grant you that, but that's a purely pragmatic consideration. And I want to know, before I die, I want to know what is the true state of the universe, not which is the most pragmatic state to hold, right?

• 40:31Sean Carroll?

  Well, that's an interesting distinction right there that we could talk about, but good. Anyway, I completely am on board with the idea that idealism in its modern guise is, you know, an intellectually respectable way to go, whether it's epistemic approaches to quantum mechanics, or idealism, or panpsychism, et cetera. I'm just not going there. That's why I'm very glad to have such an articulate spokesperson for the idea.

• 40:58Sean Carroll?

  Without getting too distracted then, you can probably anticipate, I'm going to ask a question about former Mindscape guest Scott Aronson's famous objection to integrated information theory. I mean, the great thing about IIT, everyone agrees, is that it sticks its neck out, right? It has a quantitative thing, it says this, this is the thing we're going to compute, this number phi, it's going to help tell us where the consciousness is. And Scott's objection is that he can come up with examples of things that, on face value, don't look conscious at all, like a large rectangular array of logic gates, which have a huge value for this number you're computing, but don't seem to map on to our intuitive view of consciousness. So what is your response to that?

• 41:42Speaker 03

  Yeah, so he's correct. IIT, like any good theory, if you extrapolate, it makes some rather strange predictions. In fact, I would argue, this part of the brain, the posterior part of the neocortex, that empirically seems to be like the substrate of consciousness in mammals, including humans, is like a very large array, not of neurons, and you can approximate neurons as a particular type of logical array, that have a topographic connectivity. So very, I mean, not unrelated to the type of arrays that he posulates.

• 42:22Speaker 03

  Yeah, so I think he is right. There's some very non-intuitive predictions. And so now we have to do the science. This has always been the case. You know, people way back argued, you know, at the time of the Greeks, and of course in the Renaissance, that the earth cannot be a sphere, because people would fall off. Of course they fall off on the other side. That's the most ridiculous things. You can't be on the backside of a sphere without falling off, right? So we have to be careful with things where we think, well, that's so ridiculous. We have to, sometimes we have to take things seriously, like black holes, right? That were also laughed, you know, people laughed about them, and then

• 43:03Speaker 03

  actually try to do an experiment to see, is it true? So for instance, John, people can now start to build cerebral organisms. You've heard about mini-brains in a dish, right?

• 43:13Sean Carroll?

  Yeah, yep.

• 43:14Speaker 03

  So in principle, in 10, 20, or 30 years, we'll be able to build them Like very large tissue. So if I were I to take your mind neocortex, the outermost layer of the brain that's really most closely associated with vision and consciousness and intelligence in us, it's really a pizza like tissue. It's two to three millimeter thick, like a pizza, and it's twelve to fourteen inch across. And it's highly folded and you have two of them left in right brain. So in the fullness of time, in twenty, thirty years, people will be able to grow these things in a dish.

• 43:48Speaker 03

  Right? Yeah. I mean, it seems sort of ridiculous, but I think that's gonna happen because you can reuse it to to fix. Let's say if you have Alzheimer or some other pathology, you can fix it. Well, in principle, this piece of tissue may feel like something. Maybe it just feels a vast spatial extendedness, like you get during certain meditative states when you when the meditators just talk about this vast luminosity, right? So consciousness may end up being found in very strange spaces and we have to. The only way we can verify any theory of consciousness is in us, in you and I and other people. And once we have a theory verified, then we have to go where it takes us.

• 44:29Sean Carroll?

  And, okay, so so your your answer is to bite the bullet and say, yes, this this these examples that don't seem to map onto our intuitive idea of consciousness should nevertheless count as conscious. That's that's your.

• 44:41Speaker 03

  And conversely, things that look very conscious, like L L M's, same logic applies. We have to test, are they really conscious or are they just faking it?

• 44:50Sean Carroll?

  Can we? Has anyone computed phi for an L L M?

• 44:55Speaker 03

  Yeah, so there's a paper that's that's on Bio Archive now that we're trying to to submit that shows formally within. So this is only assuming I I T is true.

• 45:05Sean Carroll?

  Yeah.

• 45:05Speaker 03

  Okay, you can, because it's it's very formal and it's very specific. So we what we what we can formally show, you have a simple model of a von Neumann machine. Okay, it's a very simple with hundred sixteen gates or something like that. And you can show you can show an actual, I mean, it's it's all simulated. So in one case, we have a simple automata. That's heavily nonlinear. In the other case, we map this automata onto a simple, but general, but perfectly general four bit computer. And you can show that the input-output states of these two systems, here a physical

• 45:43Speaker 03

  set of four nonlinear gate, here 116 gates, as you would typically find them in a von Neumann architecture, functionally they're totally equivalent. They perform the same input, give rise to the same output. So you cannot distinguish them. So by Turing, they're exactly the same. But you can show phenomenal, this has some causal power. Well, this one doesn't exist at all at the level of the whole, at the whole system, 116 gates, and only very small subset of them have a tiny bit of causal power. Why is the difference? Well, because machines, so on a typical CPU, one transistor will talk to two or three

• 46:25Speaker 03

  other transistors. But then, of course, you have endless billions of, billions of these transistors array to give you universal logic. While the, the, the way the brain is wired, you have one neuron gets input from 50,000, projects to 50,000 with heavily heavy overlap. And so the, the, this notion of causal power is radically different in one from the other. So you can show functional equivalent does not equate to phenomenal equivalence, including in the limit, you have two systems that are functionally identical. This one is highly conscious, this one isn't conscious at all, which I think is the case for L L Ms. This

• 47:06Speaker 03

  is not, we, you can't do such a proof for neuromorphic computers, nor for quantum computers. So it may well be that you can build, so there's no question, I I T says there isn't anything supernatural about the brain. So clearly you can build artifacts that are conscious, but just not the way we build them today, not the computers running in the cloud.

• 47:27Sean Carroll?

  Are you at all sympathetic to the idea, just to finish up the Scott Aaronson conversation, that I I T might be better thought of as a necessary but not sufficient condition for consciousness to happen? Like, if you don't have this integrated information, this high quantity phi, you're not conscious. But just because you do, doesn't mean you are. I mean, if you're not representing the world, if you have no semantics, et cetera, then maybe we shouldn't count it as conscious.

• 47:57Speaker 03

  Well, okay, so A, you can perfectly well, and in fact, we've done this, there are a number of papers where you can evolve, you know, in a, in a computer, you can evolve simple creatures that have high five that represent the world in a sense that there's a, what, there's a mapping between, you know, these are creatures that, that you have 10,000 of them, you let them run through mazes, you collect the best one, you perturb their genome, you, you give rise to another brain, you send them through that, you do that thousands of times, you start with randomly connected brains and you end up with brains that have mapping from the outside, the labyrinth or whatever they have to, they, they have to deal with onto their internal brain. So IIT doesn't, doesn't preclude in, at all

• 48:42Speaker 03

  that there is this lawful mapping like you and I have between the external world and the visual, the visual brain or the, um, um, or the auditory world. No, you can, I mean, who knows, you know, I, I cannot think about the space of all partial theories, but within IIT, they are, in fact, there's a thing called the central identity as part of IIT that says your conscious experience is identical to, uh, or can be, can be fully accounted for, that's a better formulation, one to one, with nothing left over on either side by the to, by the totality of the intrinsic causal power. Every aspect of your experience, including the mo, and every memory, every thought, every dream can be fully accounted

• 49:27Speaker 03

  for. Now, this may be wrong, it's a theory, but that's what the theory states.

• 50:06Speaker 01

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• 50:31Sean Carroll?

  And I do want to get on other things, but maybe a quick opportunity to talk about like the nitty gritty of looking at brains. You've mentioned mouse brains already. Are we testing? Does it even make sense to ask the question? Are we? Kristoff is showing us a little key ring with a mouse brain on it. Yes. Can you take the ideas from IIT and either test them in the mouse brain or learn about the mouse brain using these ideas? And if so, how do we do that?

• 51:03Speaker 03

  Yeah, I mean, the mouse brain, you know, people think a mouse, well, what's a mouse? It doesn't talk, you know, I'll never have dinner conversation with it. All of that's true. But again, if I take a grain of mouse brain, dog brain, elephant brain, human brain, basic hardware is all the same. It's not identical. You know, we evolved the last common ancestor between us and mice is, you know, 60 million years ago or so. But their components are remarkable the same to the extent that we just published a whole series of nature papers showing. So the brain consists of a 5,000 on the order of 5,000 different types of brain cells. Bifidocyania cells, pyramidal cells, very different types of pyramidal cells, etc. The same 5,000 cells can more or less be found in the human brain.

• 51:47Speaker 03

  It's just like genes. We, you know, our genome is on the order of 20,000 genes. The mouse genome is on the order of 20,000 genes. It's all very, very similar. But the difference is, of course, in the mouse, you know, it's much easier to do experiments and for ethical reasons, there are certain questions. You can't ask the mouse about language, of course, but you can do the basic. They're highly tactile. They're highly olfactory. They're less visual. They have vision, but they're less visual than us. So there are lots of experiments that you can do in a mouse or in similar creatures that are really very similar or relate closely to experiments that people can do in humans where you're of course limited. Typically, you don't access the human brain. You only see it indirectly. So you have to use eGene, fMRI.

• 52:32Speaker 03

  So we are all closely related. We're all nature children. We have some specialization, like a hyper-developed sense of importance. That's one big difference.

• 52:42Sean Carroll?

  I don't know, the mice might. I just don't know. But then, okay, so you're now still affiliated with the Allen Brain Institute, is that right?

• 52:51Speaker 03

  Yes, yeah, correct.

• 52:52Sean Carroll?

  And is the Allen Brain Institute a hotbed of IIT-ism, or is it more academic?

• 52:58Speaker 03

  No, no, it's purely, so, you know, we are now a thousand people. When I came, we are a hundred. When I was the chief scientist and the president, we went to 300. I stepped down, and now we are a thousand people. So we focus on a few very large projects, like cataloging all the cell types in the mouse brain, or all the cell types in the human brain, doing this, also doing development, you know, what happens in a very young, immature brain as it develops, how do cell types change, what about the atlas, we're doing these connectome projects, where we do, you know, at the finest level possible, where we don't image with photons, but with electrons, like cutting up tiny slivers, you know, two or three nanometer

• 53:40Speaker 03

  thick of brain, and cutting, you know, millions of these slices, putting them together. So we do a few very large projects that typically can't be, are not going to be done by industry and can't be done at a university. By and large, we don't think too much about consciousness and such things. We leave that to academics, like me, or like many other academics at various universities.

• 54:05Sean Carroll?

  Well, I mean, it's good. I'm very glad you said this, because I think that it's fun to talk about the big-picture philosophical questions, and they're not the same as, but they absolutely do rely on this kind of empirical work, where you're trying to figure out how many different kinds of neurons there are in the brain.

• 54:23Speaker 03

  Totally, otherwise we'd still sit around like Plato and Aristotle in the Academy days, right, 2400 years ago in Athens and shoot the breeze.

• 54:31Sean Carroll?

  Yeah.

• 54:31Speaker 03

  Without ever making progress. But that's a great thing about science, including about psychedelics, including quantum mechanics. You can ask nature the right question in the form of the correct experiment, right, and you will get an answer. That's the best thing about science, better than any other human activity.

• 54:49Sean Carroll?

  I agree. I completely agree. And so, given what we've learned and what we're still hypothesizing about, there's a bunch of questions lying out there about consciousness that are pretty down-to-earth and operational. As we've already alluded to, we want to know, are people conscious when they're dreaming? Are they conscious when they're in a coma? Are they conscious when they're six weeks after conception? Do you think we've made progress on these questions?

• 55:16Speaker 03

  Yeah. So in fact, I helped start, so one of them, very much, and all of those questions, except maybe the final one, let's come to that. So A, I helped start a company called Intrinsic Powers that brings a device that used to be a pure research prototype, developed by Giulio Giannoni, the architect of integrated information theory and a close medical colleague of his, Marcello Massimini, to test for the presence of consciousness in behavioral unresponsive patients. So if you or I have, after this conversation, a heart attack or bleeding or a car accident,

• 55:58Speaker 03

  we get into the ICU, we are unresponsive. We're clearly alive, we're unventilated, we're unresponsive. And they ask you, can you hear me? Can you see me? Can you track a flashlight with your eyes? You know, if I pinch you, will you moan or will you move a limb? You don't do any of that. You're considered behavioral unresponsive. This used to be called vegetative state.

• 56:20Speaker 03

  The tragic is four to five days out, if you remain in this day for four or five days, typically the team, the medical team will initiate discussion with your loved one. Well, what did he want? Is it time to pull the plug? Literally, they pull ventilator support. And up to ninety percent, up to nine out of ten of these patients die because of withdrawal of life critical care. Okay? Now, we do know that one quarter of these patients are conscious, but covertly conscious. So what that means, for instance, if you ask them, so you have this person lying there, you ask him, sir, imagine playing soccer for thirty seconds, and then imagine just being quiet.

• 57:05Speaker 03

  Again, ask, you ask him second time, imagine playing soccer for thirty seconds. Imagine lying quiet. Then you can see, for instance, the nice modulation in your motor cortex response. So it means this patient who is unable to communicate, where you have no idea whether there's anyone home, still can lawfully, voluntarily regulate their brain activity. Okay? And so, and together we developed this device. So essentially what it does, it knocks the brain by sending in a magnetic pulse, call it transcranial magnetic stimulation. And then you measure the response using high-density EEG, and essentially you compute the complexity of that. And IT.

• 57:48Speaker 03

  And it turns out there's an absolute threshold, point three two, it's normalized. So zero would mean it's totally flatlined. You knock the brain and there's no response. That's brain death. Or the, one would mean every point, every electrode is totally independent of the other. This doesn't happen in real brains. So typically, brain complexity is between point six and point eight typically in you and I, for instance, right now. Or when we know, when you dream, same thing. When you're in a deep sleep, it's very small complexity, below threshold, point three one. When you're in a dream state, your complexity is high. When you're under psychedelics, your complexity is high. When you're under anesthesia, your complexity is

• 58:29Speaker 03

  Low. When you're in an unambiguous coma where it's clear that you're not there, your complexity is low. So it's this very nice threshold and with very high specificity of point nine five. We can determine whether you're actually so it's a it's a primitive consciousness detector.

• 58:46Sean Carroll?

  Yeah.

• 58:46Speaker 03

  First primitive conscious detector. So again, this really shows. Independent of all these idealism, physicalism, panpsychism, we can actually make progress on these questions. We can build consciousness detectors. Right now for us, in the fullness of time, we will certainly we can develop them for every for any mammal. And maybe in the fullness of time for any system, but right now for for for humans. So that's real progress.

• 59:14Sean Carroll?

  Does it help us with the prospect of brain computer interfaces and being able to talk with people who are in a coma?

• 59:21Speaker 03

  Uh, no. So this is a purely device just to see is the the complexity of this brain, is it sufficient to support consciousness? No, separately, you can then specifically take these patients. And and you know, further do rehabilitation or or talk about if they remain in this state. So typically what happens. So most people, they the natural course of events, people either die. Or they recover some functionality. Okay, so if you remain in this state, a small subset, five to 10%, they become chronic. And then they, you know, they're typically in a home or sometimes they they get actually taken to their own home.

• 1:00:04Speaker 03

  And they remain in this state where they have either no or only minimal, sometimes people sort of recover some ability to move their eyes. In the worst case, they may not recover at all.

• 1:00:16Sean Carroll?

  Yeah. And, okay, that's, I'm sorry to hear that. I'm glad you're doing. Uh, I mean, I'm sorry to be reminded of this terrible fact about human life, but I'm glad that you're you're making progress on distinguishing between the cases that really seem to be essentially gone and those that are recoverable. Then what about the the youthfulness question? What about the fetus? And becoming conscious? Is that something that we can talk quantitatively about?

• 1:00:42Speaker 03

  Well, so all we can say, and I, in fact, I was participated in amicus brief in that anti-abortion.

• 1:00:50Speaker 03

  Lawsuit. We know.

• 1:00:54Speaker 03

  The cortex doesn't really fully develop till the second trimester.

• 1:01:00Speaker 03

  So your nervous system develops, you know, at eight to 10 week in the first trimester. But it starts developing, but then really sort of doesn't develop the connectivity and the connectivity to the external world through the thalamus. That doesn't happen till week 22 or 24. EG is also pretty much flat until then, and then you get the first so-called birth suppression EG where you get activity and then quiet, activity and quiet. And the typical pattern in you and I that doesn't happen till very late, end of third trimester where you get a more normal looking EG with all the waves developing.

• 1:01:45Speaker 03

  So it's very difficult to say right now, but before the first trimester, in the first trimester, it probably may not feel, I mean, it's very difficult to inference.

• 1:01:55Sean Carroll?

  Yeah.

• 1:01:56Speaker 03

  As far as we can tell, it probably doesn't feel a lot to be a first trimester. At the end of the second trimester, you begin to get some simple reflexivity. So in premature babies, when they need some operation, they do already limb withdraw reflexes. But that doesn't, you know.

• 1:02:14Sean Carroll?

  Yeah, this is the reflex.

• 1:02:15Speaker 03

  A Drosophila embryo does the same thing. It curves away from a source of heat like a match. So is that reflex? It's very difficult to be certain.

• 1:02:26Sean Carroll?

  Is it exciting or somewhat scary to be part of an amicus brief in front of the Supreme Court?

• 1:02:33Speaker 03

  Well, it was exciting and, you know, we were trying to do the right thing, but, you know, it didn't amount to much.

• 1:02:39Sean Carroll?

  Yeah, well.

• 1:02:39Speaker 03

  I mean, it wasn't decided on the merits of the scientific case, right? It was just decided.

• 1:02:44Sean Carroll?

  Of course.

• 1:02:44Speaker 03

  We need to send this back to the States.

• 1:02:47Sean Carroll?

  Okay, and then you already mentioned a little bit about L L Ms and your opinions about that. But is there, from I I T or from any competing theory, do we suggest some kind of roadmap for making artificial computer programs that truly are conscious? Or is that a very far way off?

• 1:03:07Speaker 03

  Well, first, why would you want to do that?

• 1:03:10Sean Carroll?

  People want to do lots of things.

• 1:03:12Speaker 03

  Okay, that's true. Yeah, so according to, so you cannot simulate it.

• 1:03:18Sean Carroll?

  Okay, that's a big claim.

• 1:03:21Speaker 03

  Yeah, because, look, you can perfectly well simulate the black hole at the center of our galaxy, right, Sagittarius A star. But have you ever worried, Sean, that if you turn on this simulation, you're next to the computer program in the computer center that runs this, you're going to be sucked into the black hole?

• 1:03:39Sean Carroll?

  No, I have not worried about that.

• 1:03:40Speaker 03

  Why not? Where's the difference?

• 1:03:44Speaker 03

  No, I kid you not, where's the difference?

• 1:03:46Sean Carroll?

  Well, the simulated test particles in the computer would be sucked into the simulated black hole.

• 1:03:52Speaker 03

  Yes, but that's all simulation. It's a difference between the real and the simulated, right? So because this computation by itself does not have causal power to bend spacetime, just like it never gets, I mean, Sean Searle made this argument, you know, decades ago, it doesn't get wet inside a rain simulation, right? Same thing, it doesn't have the causal power. Yes, so you can perfectly well, even if you were to build a computer simulation of the human brain, the complete human brain, like, you know, Henry Markham Blue Brain Project wanted to do that. In the future, we'll be able to do it, but still, and this computer simulation, of course, will wake up and speak, because it's, you know, it can do that, but it won't feel like anything, because you can't simulate it, you actually have to build it.

• 1:04:35Speaker 03

  So if you want true conscience, you have to build it. You either have to do neuromorphic engineering, where you build hardware, not simulate, you actually build hardware in the image of the brain. People are trying to do that at IBM and Intel, et cetera, or possibly quantum computers. Possibly, like, you know, Willow's at Quantum Compute Lab, et cetera.

• 1:04:58Sean Carroll?

  So embodiment might be very important for this project.

• 1:05:01Speaker 03

  Yes, yes, it's not going to be substrate independent.

• 1:05:04Sean Carroll?

  Right, okay, good.

• 1:05:05Speaker 03

  And so I don't believe, by the way, in this, you know, mind upload, right?

• 1:05:09Sean Carroll?

  No, I agree, yeah.

• 1:05:11Speaker 03

  You know, that I cut my brain, I get my brain's connectivity, I simulate it up in the cloud, and then this thing will be conscious. No, it may be able to mimic me, including my accent and everything perfectly, but it doesn't feel like anything, it's a deep fake.

• 1:05:26Sean Carroll?

  You're not worried about the Matrix?

• 1:05:28Speaker 03

  No. I'm worried about many things, but not the matrix.

• 1:05:32Sean Carroll?

  Well, you've written, I'm sorry that it's gotten, taken this long to get there, but you've written a provocative book just last year. Do you want to give the title or should I read it?

• 1:05:41Speaker 03

  Then I Am Myself the World, which is taken from the second act of Richard Wagner's opera Tristan e Solda, where the eponymous lovers, you know, have this union where, I mean, they make love on stage, basically, but they want to overcome their own self. And so they have what's in modern language called a mystical experience. They become, they lose the boundaries between themselves, between Tristan e Solda and the rest of the universe. So they feel they are one with the universe, which is what really, one of the defining features of what's called a mystical experience.

• 1:06:18Sean Carroll?

  Well, this is what we can talk about when you're at a certain stage of your successful academic career. You're talking about expanding consciousness now, which is certainly fraught territory.

• 1:06:30Speaker 03

  Well, yeah, I mean, yes, I've been fortunate enough to have such an extraordinary experience and it leaves you totally unmoored. It leaves you completely flabbergasted. It leaves you, you know, I had this when I was 65 and, you know, I thought my, the, my metaphysics, my sense of what exists has been fully established and, you know, at 65 isn't going to budge anymore. And then suddenly you have this ontological earthquake where all your, literally all the plates shift and everything you lived and, you know, everything you did suddenly looks very, very different. So it's, for sure, it's a transformative experience.

• 1:07:12Speaker 03

  In a sense, if you undergo this, there's a distinct before and after, you'll never look at things the same way again, which is another defining hallmark of a transformative experience.

• 1:07:24Sean Carroll?

  So we're talking about some kind of psychedelics or other pharmaceuticals or a purely like meditative state?

• 1:07:31Speaker 03

  No, this was, this was with, with help.

• 1:07:37Sean Carroll?

  Yeah, okay. So, but you're a neuroscientist, you know, that you, you had an experience that was caused by prodding your neurons with chemicals. So how does that help you get insight into the fundamental nature of reality?

• 1:07:55Speaker 03

  Okay, so you're totally right. My brain was a substrate of this experience. I don't doubt that for one second, helped or not.

• 1:08:07Speaker 03

  But the, so William James talks about it in this wonderful book. I can warmly recommend, I warmly recommend it to everyone to read it. It hasn't aged, has aged very well, that he first wrote in 1906. You know, the father of American psychology, the varieties of religious experience. What he talks about, mystical experience. And he says they bring, one of the defining hallmarks of them, this, what he calls noetic quality. You know, from nous, knowledge, Greek. You bring back this, this experience and it has powerful authority over you. You cannot help but now try to seek, you know, I'm, I'm still a rational scientist in person.

• 1:08:49Speaker 03

  So what, what I try to do is try to see how does what I experience, how is that compatible with my view of everything else, including science, including brain science, including knowledge that my brain was a substrate of, of this particular experience. So you, I think you can reconcile both of those things. Look, it's a little bit like, imagine, Sean, the following scenario. No one dreams, okay? People, you've never read about dream. When people go to sleep, they just sleep, that's it. And you have one experience, one. How would that change your life?

• 1:09:31Speaker 03

  If you only had one experience, one dream experience, you know, where you met your long lost parents or friends or et cetera, it would sort of profoundly affect you, right?

• 1:09:44Sean Carroll?

  Absolutely, would not, I, I hope it would not lead me to change my ontological view of the world.

• 1:09:51Speaker 03

  Well, because you haven't had, look, and I take no, and Jane says explicitly, you can't convince other people of your abuse, and I'm not trying to. This is just my experience. I do know that these types of experience that I write about are common in literature, common across all cultures, right? Lots of people in lots of different settings have written about them. So they're not that rare. It's not unheard of. And so the challenge is, if you accept them, you know, if you accept them, what does this tell you about the world? And in particular, what does it tell you about the metaphysical, the metaphysics about the world? So you can continue to, I can continue to do all my science, all my neuroscience, et cetera.

• 1:10:34Speaker 03

  But it really shook the ontological foundation of, which is why I'm now much more sympathetic to idealism, which I hadn't thought about for 50 years.

• 1:10:43Sean Carroll?

  Okay, so my question was going to be, so what is the shift in your metaphysics? But is that it, that you're much more sympathetic to idealism?

• 1:10:53Speaker 03

  Yeah, because what I experienced there was effectively the world at large that there was no self anymore. Self was completely gone. Christ was gone. There wasn't a body. There wasn't anything like that. And I, instead, I experienced the universe at large, literally. The galaxy, I mean, the universe at large. Yeah, I know it sounds corny and all of that, but

• 1:11:13Sean Carroll?

  That's okay.

• 1:11:13Speaker 03

  But, but, but that's what you experience. And you're in this time, there's no passage of time. It's not too slow or too long, this moment, you know. And so, yeah, so you run around, this was at midnight on a beach in somewhere in Brazil, and you, you know, you're totally confused the next weeks and months, right? Because you're trying to fit in, you know, how does, how does this accord with everything else? I, you know, I know. And then sort of I thought back, Schopenhauer, I came upon this remarkable quote of Schopenhauer, where he talks about 200 years ago in his book, well, his only book he really wrote, The World as Will and Representation, where he talks about states like that.

• 1:11:56Speaker 03

  And as far as we know, he was not a, I mean, meditation didn't exist at the time. In the West psychedelics really didn't he never had any experience like that that was of course before we encountered opium and other substances so he just thought about these these things and then yeah I looked around at idealism and then I came across this philosopher computer scientist Bernardo Castrop who who espouses this this modern form of of idealism.

• 1:12:24Sean Carroll?

  And in your book you're going to suggest that people can understand consciousness better and and expand it through these these kind of intense experiences?

• 1:12:34Speaker 03

  I would certainly suggest yes I so I grew up at a time when you know I did you know I was heavily into alcohol like many of us in the West but nothing else but but that's changed over the last 10 years yeah they they can reveal you so A they can reveal the states of self where where your ego is dissolved ego dissolution where there's no self and you can experience a profound beauty like here I'm looking at the island the forest the green lush forest you can just see the beauty the transcendent beauty of it whole and there's no self to get in the way I mean we need the self it we it's necessary to do long-term planning all of that but it also

• 1:13:19Speaker 03

  constantly get in the way right it's always about me me me me and me I mean look at the most senior political personality in this country who shall remain nameless right or the two of them both of them right?

• 1:13:32Sean Carroll?

  Yes.

• 1:13:32Speaker 03

  And it's all about me me me me me and so suddenly you have this experience of loss of self and you and you realize well that's perfectly fine the universe is profoundly beautiful without me so I think that's really an essential experience that most everyone should have and can have in a safe in a if you do it in a safe manner now not everyone there are certain dangers some of these substances are very powerful so you have to be very cautious you know you have to use all the proper safeguards etc but I think for most people they can reveal aspects of consciousness that they haven't thought about or they haven't they have never experienced or they have never imagined.

• 1:14:13Sean Carroll?

  Good should we wind things up by talking about quantum mechanics?

• 1:14:17Speaker 03

  Sure it seems like a good thing.

• 1:14:20Sean Carroll?

  Well I mean we've talked about it already but you have a paper out not too long ago about the possibility that quantum mechanics does play a role in consciousness.

• 1:14:29Speaker 03

  Yeah, so we initiated this collaboration with Hartmut Nevin, who is a physicist and also is back on his computational neuroscience like me. In fact, we had our same advisor back in Germany. But since then, he's a vice president now at Google and heads the quantum compute Google group in Santa Barbara, busy building these large-scale quantum computers. And then together with a bunch of experimentalists, particularly Ken Kosick, who's at University of California in Santa Barbara, and Luca Turin, who's at the university in UK. And their idea is, so there's radical work

• 1:15:12Speaker 03

  and then right now there's experimental work trying to test it, that sort of inverting Penrose, really, you know, Penrose famously argued within his objective reduction that the collapse of the wave function, you have a particular system, it's in a superposition, that collapse because of interactions with the environment, and that gives rise to a little ping, a little bit, a little conscious moment. That's his, you know, that's his argument. And then he got together with the anesthesiologists, Stu Hammeroff, you know, Michael Tubby and all of that. But let's divorce the instantiation of that Michael Tubby from that idea. It's controversial, but has remained irresistible to many, many people.

• 1:15:57Speaker 03

  All right, so we're inverting that because we're saying, well, if you have a system that consists out of two or three, or more than one qubit that are all entangled, something Roger Penrose never considered, then if that's true, you could then use that to communicate faster-than-light information, violating relativity theory, that no one really wants to violate, right? So you can invert that by saying, well, no, it is when the system goes into superposition that you create a conscious moment. And if you have a system with 20, let's say, qubits, then they go into the superposition of 20 qubits.

• 1:16:40Speaker 03

  But you, of course, the defining thing of consciousness is you only ever experience a definite experience, right?

• 1:16:48Sean Carroll?

  Not a superposition.

• 1:16:49Speaker 03

  And so, so this is where the many world interpretations come in. I only travel down one of these branches of the two to the end possibility. You know, if I just have up down states, two to the end universes. And that's the one I consciously experience. And what you experience depends on the way these interact. And here you could use, for example, I R T to explain that. So, so it, it, it sort of inverts Roger's proposal. And if that's true, you can then sort of build quantum systems that could interact with your consciousness, as long as you can get a system. You know, if the latest iPhone has quantum computing and is entangled with my qubits

• 1:17:31Speaker 03

  in my brain, then that would be one conscious mind. So you could expand your consciousness if you have the right technology. Now, the, it's, you know, it's, it's one of many crazy, crazy sounding ideas in, in the interface between consciousness and quantum mechanics. But the great thing is we're trying to test it now. And this again, where we come back to this thing, if you ask the right experiment, you can get an answer. So there have been since, you know, thirty years, Klaus Schulten's work, these hypothesis that biological system, in particular bird navigation, avian navigation uses a quantum

• 1:18:16Speaker 03

  compass, right? In, in quantum, in the interaction in the eye, there you have this, the interaction between photons and the, and the molecule. And this depends, weakly seems to depend on magnetic field. And that songbirds can you, can use that to navigate across vast distances. Ultimately, that's based on a radical pair mechanism. That's one hypothesis, or on nuclear spin interactions, another one. So we are trying to test that. There has been one claim that xenon, so you take the rare gas xenon.

• 1:18:52Speaker 03

  It's an anesthetic. This is known. It's actually very good anesthetic because it's rare gas. It doesn't interact much with anything. It's very safe. It doesn't burn, so it can be used in the clinic. It's just very expensive, so it's not really used in day to day practice. But it is a, it is an anesthetic. There's one claim, there's this an isotope dependency. That, that xenon one twenty eight, one twenty nine, one thirty and one thirty one have different anesthetic potencies. Now, the only diff, the, the, the, the difference in atomic mass is minute, is under one percent. So the, it's, the hypothesis is unlikely to be due to the difference in mass. But the most critical difference is that one twenty eight and one thirty has been zero. Hmm.

• 1:19:36Speaker 03

  While one twenty nine and one thirty one has been respectively one half and three half. So now together, Luca Turin is trying to test this very simple experiment in flies. In other words, if you take a bunch of flies, you put them in a tube. So now you see thirty rosofilar, fruit flies in a tube. You introduce a gas, various types, you know, different types of xenon, different isotopes dependent xenon gas. And you compress. And at some point, you see when you reach certain pressure that the, the flies are all immobile. They're anesthetized. And then you release them again. So you can do this experiment multiple times.

• 1:20:14Speaker 03

  So the, the very simple test is, is it true that this dependency, how deep you have to plunge? The plunger into that vial with xenon gas until you achieve immobility? That here stands in for anesthetic potency. Does that depend on the isotope of xenon? Good. And a different model system that we're trying to do with cancotic. What about human, these human cerebral organoids made out of human pluripotent stem cells?

• 1:20:46Speaker 03

  If you can get them, if you put xenon on, again, ultimately, the tissue would usually these tissue, these mini brains fire action potential. If you put sufficient xenon in, that ceases, that stops the firing. So does that the point, the precise point when that firing stops, does that depend on the isotope? Is it going to be different for xenon 129 versus xenon 130? That's the question we're asking.

• 1:21:13Sean Carroll?

  It's certainly an experiment very well worth doing. I guess it's late in the podcast, so I can ask one technical question. The hypothesis that a system being in superposition is relevant for consciousness somehow. That's what bugged me a little bit when I saw the paper, because being in superposition is sort of not an objective fact, right? That is relative to what basis you're using to describe your system. So is there a more physical criterion that we can replace for that?

• 1:21:40Speaker 03

  No, not right now.

• 1:21:44Sean Carroll?

  Okay. That's why it's science. We got to do it.

• 1:21:46Speaker 03

  Yes.

• 1:21:47Sean Carroll?

  What is your thought? If you had to place Bayesian priors here, do you think that quantum mechanics is super important for consciousness?

• 1:21:56Speaker 03

  Probably not in the human brain.

• 1:21:59Sean Carroll?

  Okay.

• 1:22:00Speaker 03

  For all the reasons. On the other hand, look, evolution, you know, it's been around since four or five billion years, roughly, right? And so evolution is very clever. It's done all sorts of things. If it's not outlawed by the laws of physics, you know, somewhere, and if it's really beneficial for the organism, then it may well have been exploited. Would I bet my house on it? No.

• 1:22:25Sean Carroll?

  Well, not at even money.

• 1:22:28Speaker 03

  That's why we're doing the experiment.

• 1:22:29Sean Carroll?

  Yeah, that's why we do the experiment. And that's a very good philosophy to end with. So Christoph Koch, thanks so much for being on the Mindscape Podcast.

• 1:22:35Speaker 03

  Thank you very much for having me, Sean. That was very enjoyable. That was very enjoyable.

• 1:22:39Sean Carroll?

  Good.

• 1:22:40Speaker 03

  What is your paper about? You said you just published a paper 10 days ago?

• 1:22:45Sean Carroll?

  Oh, it was just a review article for Nature, an essay about the 100th anniversary of quantum mechanics and why it's still controversial, why it's still difficult to really figure out and get a consensus on what quantum mechanics actually says.

• 1:22:59Speaker 03

  That's right, 1925.

• 1:23:02Sean Carroll?

  It's the quantum year. It's the United Nations has said that this is the

• 1:23:06Speaker 03

  Oh, that's right, yeah.

• 1:23:06Sean Carroll?

  Year of the quantum, yeah, so and we still don't understand it.

• 1:23:09Speaker 03

  And it's not true for general relativity, right? There are none of these controversies swelling around GR.

• 1:23:13Sean Carroll?

  No other theory has these controversies. There's not like a whole subset of people doing philosophy of electromagnetism, right? It's a quantum mechanics is the one that and I think it's an embarrassing situation for the physics community because we have not addressed the problem. I think that's an issue. Yeah.

• 1:23:32Speaker 03

  But it's also an opportunity.

• 1:23:34Sean Carroll?

  Exactly. Well, I like to say like I personally am very slow, so I'm perfectly happy with the rest of the community not racing me to do this. I'm trying to figure it out myself.

• 1:23:44Speaker 03

  Yeah, so please send it to me, the article.

• 1:23:46Sean Carroll?

  I will do that. Thanks.

• 1:23:48Speaker 03

  Thank you. That was fun.

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