The Physics of Consciousness

Theoretical physicist Dr. Michio Kaku joins hosts Dr. Heather Berlin and Dr. Christof Koch to explore what physics can teach us about consciousness and reality itself. Dr. Kaku argues that consciousness is best understood as feedback loops, shaping the walls of our own Perception Box™ long before we're aware of it. The conversation asks if quantum mechanics has anything to do with a "warm, wet" brain, illuminating a central idea of the Perception Box, a framework developed by Elizabeth R. Koch for understanding the forces within us that shape how we see ourselves, relate to others, and move through the world. Dr. Michio Kaku is a theoretical physicist, bestselling author, acclaimed public speaker, renowned futurist, and popularizer of science. As co-founder of String Field Theory, Dr. Kaku carries on Einstein's quest to unite the four fundamental forces of nature into a single grand unified theory of everything. He received a B. S. (summa cum laude) from Harvard University in 1968, then went on to the Berkeley Radiation Laboratory at the University of California, Berkeley, where he received a Ph. D. in 1972. In 1973, he held a lectureship at Princeton University. Dr. Heather Berlin is a neuroscientist, clinical psychologist, and Professor of Psychiatry and Neuroscience at the Icahn School of Medicine at Mount Sinai in New York City. Dr. Christof Koch is Chief Scientist for the Tiny Blue Dot Foundation and the current Meritorious Investigator and former President of the Allen Institute for Brain Science. Join us for new episodes every Thursday. Follow the show on YouTube, Spotify, Apple Podcasts, Amazon Music, or wherever podcasts are found. Love the show? Write us a review on your podcast app, or tell a friend about the show. Visit unlikelycollaborators.com for more information. Chapters: 00:00 Intro 01:48 Can Physics Explain Consciousness? 03:24 Defining Consciousness vs. Intelligence 09:57 Schrödinger's Cat and the Many-Worlds Theory 12:47 Do Quantum Effects Scale Up to the Brain? 16:13 Could AI Ever Be Conscious? 21:04 Perception Box Question: How Do Others Perceive You? 23:15 Kaku's Multiple Identities Through Life

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

• 0:00Speaker 00

  Most of the universe is invisible, invisible, untouchable, but we're so wedded to this idea of what you see is what you get.

• 0:09Heather Berlin?

  Hi, I'm Elizabeth Koch. What's a perception box? It's this invisible mental box that each one of us lives inside, built from the material of our beliefs, life experiences, and the meaning we've made out of those experiences. You could think of it as a kind of reality filter that's constantly shaping how we see ourselves, other people, and the world around us. This podcast explores how, although the walls of this box are always present, they can expand in moments of curiosity, awe, and wonder, or contract in response to fear, anxiety, and anger. In each episode, we invite experts to share how to create lasting shifts in our perception.

• 0:54Heather Berlin?

  I'd like to introduce our esteemed hosts, Heather Berlin, Professor of Psychiatry and Neuroscience at the Icahn School of Medicine at Mount Sinai, and Christoph Koch, Chief Scientist for the Tiny Blue Dot Foundation and former president of the Allen Institute for Brain Science. Welcome to the Science of Perception Box. This week, our guest is Dr. Michio Kaku. Seen through the lens of the perception box, we're always interpreting incomplete information. These filters can close our minds and put us at odds with one another and with ourselves, but they don't need to. By engaging curiosity, we can reconsider our deeply held convictions and consider that there might be more to the story.

• 1:38Heather Berlin?

  This expanded, curious way of being opens us up to new dimensions, both outside us and the universe at large, and in the universe within ourselves. Christoph, what do you think that physics can teach us about consciousness?

• 1:53Speaker 02

  Well, I mean, I guess physics is foundational to understanding anything, including the brain, which is, after all, a piece of furniture of the universe like any other. I think the more interesting question is that we and many people are interested in is to what extent do we need quantum mechanics to understand consciousness that takes place in a brain that's warm and wet? And most people would assume can be studied using classical physics.

• 2:19Heather Berlin?

  Do you think that above and beyond neuroscience, that we need to look toward things like quantum mechanics to understand the brain?

• 2:28Speaker 02

  It's clear that the brain is an organ, a physical organ, that's subject to the laws of quantum mechanics. No one doubts that. But the question is, the more sort of interesting aspect of quantum mechanics, Schrödinger's cat and entanglement, are these aspects necessary to understand, A, in general, brain processing? And B, more particular, are they necessary to understand the nature of consciousness? Many people have said so. Of course, most famously, Roger Penrose has argued that we need quantum mechanics, the collapse of the wave function, to understand, which is at the heart of consciousness. We don't know whether that's true from an empirical point of view.

• 3:09Heather Berlin?

  Well, fortunately, we're lucky enough to have a theoretical physicist with us to help answer these big questions. So I'd like to welcome to the podcast Professor Michio Kaku. Thanks for being here.

• 3:22Speaker 00

  Glad to be on.

• 3:23Heather Berlin?

  As a theoretical physicist, I wanted to ask you first, how did you become interested in consciousness? And also, how do you define consciousness versus, say, intelligence?

• 3:33Speaker 00

  Well, as a physicist, we take reality as a given, but then we begin to realize that reality is not what we thought it was. We have a multiverse of ideas. Quantum mechanics deals with uncertainty. And now we have string theory, which talks about billions and billions of different kinds of alternate realities. And so we're beginning to realize that reality is much deeper, much more profound than we originally thought because of the fact that there are alternate realities coming out of quantum mechanics. And this is why we have atomic physics. This is why we have stars. This is why we have the Big Bang. All of them exist in a, in a parallel world.

• 4:12Heather Berlin?

  So how would you define consciousness?

• 4:16Speaker 00

  First of all, a definition. I think a definition would be that you calculate the number of feedback loops necessary to create a picture of the world around you. And so, for example, a thermostat. A thermostat, to me, has one unit of consciousness. It just measures the temperature and alters the temperature with a feedback loop. A plant may have 10 units of consciousness because it has to understand rainfall. It has to understand soil. It has to understand oxygen content, so on and so forth. An alligator may have, who knows, 50 or so levels of consciousness and feedback loops because it has to understand where to find mates,

• 5:00Speaker 00

  where to find food, and how to, how to capture the prey. And then the question is, the big question is, what about us? I say that the prefrontal cortex here is the human brain. And what does it do that differentiates itself from the animals? It is a time machine. It sees and tries to quantify the future. You talk to a person, what are they thinking about? The future. They're daydreaming. What if I do this? What if I date that person? What if I steal from a bank or whatever? We constantly live in the future. So this part of the brain is a time machine.

• 5:40Heather Berlin?

  I think I would argue, maybe Christoph would too, is that, you know, this experience of consciousness is just raw, subjective experience of feeling of pain, that you don't even need a sense of self or a sense of thinking about the future to have it, that to have pure sensation is very, it's very visceral, and you don't need these other levels of it, these more complex levels of planning or thinking about the future. What would you say, Christoph?

• 6:05Speaker 02

  There's nothing intelligent about a god-awful toothache when it's really pounding away and your entire mind is filled by this god-awful pain. The future recedes, the past recedes. You're not thinking more dating or sex or anything anymore. All you're thinking is you're fully attending and you're fully conscious of this bad molar.

• 6:27Heather Berlin?

  And do you think that consciousness is a property of the universe? Or is it just tied to our neurons firing?

• 6:35Speaker 00

  I think it's both. I think because of the universe the way it is, because the universe prefers survival of the fittest, it means that organisms which are fit survive. And the fitness of the humans, why we are here today, is the cerebral cortex. This is why we're here today and not animals that are simply fighting over tooth and fang over dinner. We have a cerebral cortex. We look at the future. This is a time machine. And that's what I'm saying. That's what separates us from the animal kingdom. And so when we do an IQ test of animals going all the way to the thermostat, you start with one with a thermostat, and you go all the way up to the humans, and then you have how many feedback loops? Hundreds of feedback loops going inside the brain.

• 7:20Speaker 00

  Because the brain is a time machine.

• 7:22Speaker 02

  Intelligence and consciousness are the same.

• 7:25Speaker 00

  One is a, one is a subset of the other.

• 7:27Speaker 02

  Which one?

• 7:27Speaker 00

  I think intelligence is a subset of consciousness.

• 7:30Speaker 02

  The consciousness is wider.

• 7:31Speaker 00

  Wider. Consciousness is awareness. Awareness of what's around you, past, present, in time, as well as what's around you. That's consciousness.

• 7:41Speaker 02

  Okay, now, the philosopher David Chalmers has made this argument that all the laws of physics, including the laws of evolution of Darwin, are compatible with everything we've just said, including evolution of humans. But still, there's this additional fact of the matter. It feels like something. It feels like something to be a human and to time travel. And it's not apparent, that's his point. He calls it the heart problem. It's not apparent how feelings, you know, it feels like something to think about the future or to have pain. Where do feelings come into the universe?

• 8:17Speaker 00

  Well, the question is, what about a robot? If we have mechanical robots that can become smarter and smarter with time, at what point will the robot say, ouch, I feel pain? Okay?

• 8:29Speaker 02

  Okay, but it still doesn't-

• 8:30Speaker 00

  I think that could be wired in, heart-wired into a robot.

• 8:34Heather Berlin?

  Let's think about reality itself. String theory suggests that most of our, most of reality is invisible to us. And does that theory imply, then, that our perception of the world is fundamentally limited?

• 8:50Speaker 00

  That's right. For example, dark matter, which actually makes up most of the universe, is invisible. And we're clueless going up against the fact that, that most of the universe is invisible, made out of dark matter, and we don't even know what dark matter is. And then there's dark energy. What about atoms? Atoms make up 4%. 4% of the, the universe consists of atoms, molecules, and so on and so forth. And then when you talk about higher molecules, we're only a fraction of a percent of the universe. When we talk about carbon, we talk about DNA, we talk about microorganisms. We're only a tiny fraction of what's out there in the universe. And so we're just like children.

• 9:35Speaker 00

  We're children just beginning to realize that, that in the forest, there are trees that we can't even imagine that are staring at us. But we're so wedded to this idea of what you see is what you get. Most of the universe is invisible. Invisible, untouchable, yet it makes the universe the universe that we know and love.

• 9:57Heather Berlin?

  So does your understanding of quantum physics change the way that you personally experience reality on a day-to-day basis?

• 10:04Speaker 00

  Yes. Sometimes when I look in the mirror, I ask myself, is that really me? First of all, that image is about a light second away from, from me because it takes a light second for the image to go to the mirror and back. And then I begin to realize that what I'm seeing is not really me. What I'm seeing is a me that used to be a light second ago. And then I realized that that's nothing but one reality of infinite number of realities, parallel realities. This gets us into Schrodinger's cat. The Schrodinger's cat problem is you put a cat in a box and put a gun next to the cat, okay? And then you ask yourself, you know, before I open the box, is the cat, you know, alive, dead?

• 10:49Speaker 00

  What happens when you do open the box, okay? And the fact is that the cat can be both alive and dead mathematically until you open the box. And then you begin to realize, this is crazy. This is absurd. But it's called reality, quantum reality. And now on top of that, we have yet another reality. People wonder, before you open the box, the cat lives in a never never state of being alive and dead simultaneously. And you say to yourself, this is stupid. How can you be dead and alive simultaneously? Well, that's because you didn't open the box, okay? So the Schrodinger interpretation and the Heisenberg interpretation have been challenged by philosophers.

• 11:33Speaker 00

  Philosophers say, this is nonsense. How can you be dead and alive simultaneously? Well, there's a new way of looking at it. The new way of looking at it is that the universe splits in half. And there's an alternate universe opening up.

• 11:48Speaker 02

  The many worlds theory.

• 11:50Speaker 00

  And this is the many worlds theory of Hugh Everett, which is now the dominant theory within theoretical physics. I'm a physicist. What I work with is the Everett interpretation of many worlds, that not just one world exists, but perhaps an infinite number of worlds exists. And so, for example, I work in something called string theory. String theory, we think, is the final theory, the theory that eluded Einstein for the last 30 years of his life. But the problem with string theory is that it has more than one solution. One solution looks very much like our universe. We should say hurrah, we should yell and scream, we got it, a theory of everything. But then a critic would say, but wait a minute,

• 12:33Speaker 00

  don't you have theories of almost everything as well? How many theories of almost everything are there? Perhaps an infinite number. And then you realize, oh, my God, this is not a theory of everything. It's a theory of nothing.

• 12:47Heather Berlin?

  Do the things, the perturbations and the things that happen at the quantum scale scale enough, up enough, to actually have an impact?

• 12:56Speaker 02

  In a warm brain?

• 12:57Heather Berlin?

  In a warm brain at a certain temperature, when on consciousness, when we measure it in units of whether a neuron fires or not, that's our information processing system, right? A unit of information would be if a neuron communicates to another neuron, right? So according to Hameroff and Penrose, these quantum, you know, movements, the events, let's call them, are happening and affecting the microtubules, the structure of the axons of the neurons. Does that scale up to impact whether the neuron fires or not? Because that's the unit, that's the classical physics unit that we care about when we're thinking about information processing and consciousness. So I guess the question is, within a warm brain,

• 13:41Heather Berlin?

  does quantum mechanics really make a difference in terms of if we're conscious of something or not?

• 13:46Speaker 00

  Well, first of all, quantum mechanics is the foundation of everything. That's why we're here today, so on and so forth, right? And the irony is that even though it is the theory of everything, quantum mechanics, there's no universal understanding of quantum mechanics at the fundamental philosophical level. What does it mean to make an observation? Some people think that to make an observation, the universe splits in half. Other people say the universe has already split in half and is constantly splitting in half. Other people say that this is a bunch of nonsense. The universe is whole, it's one. And so there's no unified interpretation of quantum mechanics. Now, the results are outstanding and reproducible, also viable. We know that quantum mechanics works every time.

• 14:31Speaker 02

  There are now ongoing, interesting experiments to try to test another aspect of quantum mechanics, namely, so xenon is a rare gas, you know, it's on the right of the periodic table. And xenon turns out to be an anesthetic. This was first discovered by divers when they put xenon, when they do deep water diving. Now, it turns out there's one claim that different isotopes, that xenon 129 and 130, 131, chemically, they all look exactly the same. They have eight, you know, they have a complete shell of eight electrons, but they have different number of neutrons, that there's different anesthetic potency, so that the way anesthetic affects

• 15:15Speaker 02

  an animal under 129 is different from 128, is different from 131. And the claim is, what makes the difference is the nuclear spin involved. The ones that have low anesthetic potency have one half and three half nuclear spin, and the one with higher anesthetic potency have no nuclear spin.

• 15:37Speaker 00

  Therefore, what's the conclusion?

• 15:40Speaker 02

  The only conclusion, if this is true, which remains controversial, I think one can conclude that mere chemistry, this is interesting for brain scientists, that mere chemistry may not be enough to explain all of the function of the brain. This would be front page news. This would be front page news if you can show empirically that chemistry isn't enough to explain the brain, because then it turns out a nuclear property that the vast majority of brain scientists think is utterly irrelevant to the brain may actually be important.

• 16:13Speaker 00

  Well, this actually is part of a debate within artificial intelligence communities. If you build a robot with a very sophisticated brain, it is classical, not quantum mechanical. It's neurons with transistors. Transistors are not necessarily quantum mechanical. They fire or they don't fire, okay? So if you create a robot, at what point does it begin to interfere with quantum mechanics? Because a robot is classical. A robot does not have neurons that fire quantum mechanically. The point I'm raising is that a robot of sufficient intelligence at some point may become quantum mechanical. In other words, our brain, we think, is not quantum mechanical, has neurons. Neurons fire or don't fire.

• 16:58Speaker 00

  Therefore, it's not a quantum mechanical question. But when you start to put trillion, billions of neurons together, then I think quantum mechanics does begin to become part of the brain.

• 17:08Speaker 02

  I'm not totally clear how amassing a lot of classical component, even if you have a very large number, how just classical component would give you non deterministic physics, unless you put it in at the bottom. I do hear your argument that if, that if transistors go down to one or two atoms, then you have to take their quantum mechanical properties into account, right? So I do think it's possible that very soon, I mean, people are building, of course, quantum computers and you've written a lot of interesting things about it. But even, but today, conventional computers, like the ones that we all carry in our pockets, they are still classical, right? But if we continue to reduce the line width of computers' size,

• 17:53Speaker 02

  then very soon we'll run into quantum mechanics.

• 17:56Heather Berlin?

  As much as I don't think, based on the evidence, that what's happening at the quantum level is affecting consciousness in the human brain, I do like the argument that these other non organic systems might not be conscious because they're operating in a classic physics kind of system. But if we ultimately, we build a quantum, you know, computing system, that that could potentially be conscious.

• 18:20Speaker 00

  Well, I once attended a talk about the neuroscience of the human brain, looking at cells. And the author said that, well, there's leakage, that these cells, these neurons are not perfect. They sometimes fire correctly, they sometimes don't fire correctly. That's just the way Mother Nature created us. And at that point, you begin to wonder, now, wait a minute, robots don't necessarily have that problem. But as robots become more and more sophisticated and more and more, more like organic robots, then that leakage problem is going to dominate. In other words, what I'm trying to say is that maybe Penrose is not entirely wrong, that the leakage of neurons is going to affect even classical transistors.

• 19:05Speaker 00

  That transistors will eventually leak, okay? When you get small enough.

• 19:08Speaker 02

  By leak, you mean behave non deterministically. But of course, even today's, for instance, chat G P T, you can ask it the same question multiple times. And already today, on today's computers, you'll get different answers, right? So even practically speaking, today, they are non deterministic.

• 19:25Speaker 00

  But not because of quantum mechanics?

• 19:26Speaker 02

  It seems to me you are arguing that potentially every living thing is conscious because they all have feedback loops of one thought or another.

• 19:35Heather Berlin?

  This is in line, I think, with the integrated information theory of consciousness that Kristoff, you're very much a proponent of. Let's say a thermostat has a unit, a bit of information, right? And you can scale it up. And so there is this kind of panpsychism that other things, that anything that has bits of information has a bit of consciousness. But it really then gets into this idea of what does it, what does that even mean? What is consciousness? And how would you know if an A I system had it? How would you know?

• 20:03Speaker 00

  As long as it has a feedback loop, I say it has consciousness measurable all the way going down to a thermostat. So I would say that even if it doesn't look intelligent, it has a unit of consciousness, a feedback loop. One feedback loop to me is consciousness on the elementary level.

• 20:23Heather Berlin?

  Which is similar to this integrated information theory, which I often, my argument is, well, what does consciousness even mean at that point? What does it feel like to be one feedback loop? Does that feel like something?

• 20:33Speaker 02

  If you break, yes, if you break the loop open, it would feel like something. And then if you break it open, it doesn't feel like anything anymore. So in principle, I can imagine it's a very, very primitive form. Like you wake up in the middle of the night, you're somewhere, and all you know, I'm there. You don't even know where you are, who you are, how you got there. All you are, I'm here. And that may be a very simple, primitive form of consciousness.

• 21:04Heather Berlin?

  Every week, we end the episode by asking one question that opens up our own perception box. And this week, Kristoff chose the question. So he's going to ask us a question that's going to open us up in some way, or make us think about our own, the way we see our reality through our own brains.

• 21:23Speaker 02

  So an important part of our construction of reality is the way we think about ourselves, and the way we believe others think about ourselves. You know, this ability is called mind reading. You know, I'm trying to infer what your mind thinks about me. Was there ever a discrepancy where you thought this person thinks about me one way, but obviously, the person thought about you in a very different way? Has there ever been this clash between your expectations and what was actually the case?

• 21:55Speaker 00

  Well, I think we all go through phases, from childhood to adulthood. And in each phase, people see you differently. And so there are basically multiple personalities, multiple images of you, depending upon when you made that acquaintance. Okay. And so one of my earliest encounters with this was when I was in high school. I went to the National Science Fair, and I met Edward Teller, father of the hydrogen bomb, right? And he arranged for me to get a scholarship to Harvard. That was one reality. Then, the very day that I

• 22:36Speaker 00

  graduated from Harvard, I went into the United States infantry, because the Vietnam War was at its peak. So, right after getting my diploma from Harvard, I took an airplane, went to Fort Benning, Georgia, and fired machine guns, and AK-47s, not AK-47s, but M16s, M15s, almost the entire arsenal of the United States Army. And I began to use my physics to understand the nature of weapons, and how dangerous they are, and the volatility of these devices. And so then I said to myself, who is the real me? And then after that, I decided to

• 23:21Speaker 00

  go on radio and television, to talk about my experiences. And I had my own radio show, I had my own TV interviews. And so there was a third incarnation. So then the question that people simply ask is, who are you? And it depends on at what era or what age the question was asked. Because I've been through several different eras, starting with a starstruck young kid, building an atom smasher in his garage, to carrying an M14 automatic weapon in the Army, to holding a microphone, talking about radio and printed media to the world of today.

• 24:05Heather Berlin?

  I think that's such a great, that's a great answer, first of all. And so amazing, the things that you've done in your evolution. But I think that relates to everyone, right? We all go through these different phases in life. And, and people, I think, put you in a box, depending on when they knew you, or how they knew you, when they met you, right? And so I think people who are observing you, talking about observation, you know, see you in this one state, think it's a stable, steady state, but it's not. You're constantly evolving and changing. And so I think we all have to be cognizant of our own perception box, the way we perceive other people, and that people are constantly changing, and they're not just one thing, right? And just like you're a different person than when you're at work, or with your parents, than you are when you're out with your friends, or you're with your romantic partner.

• 24:48Speaker 02

  It is important, because we have very simple models of, we have very sophisticated models about ourselves. We realize we change, we're not the same. But our models of others tend to be much simpler.

• 24:59Heather Berlin?

  Agreed. Yes.

• 25:01Speaker 02

  Because we don't access their minds. We have to infer them, using this mind-reading ability.

• 25:06Heather Berlin?

  Right. All we know is our own perception. And we have to kind of weave together a narrative to try to make an observation about others, and how they perceive the world. Yes. Well, on that note, I want to thank you, Professor Michio Kaku.

• 25:20Speaker 02

  My pleasure.

• 25:21Heather Berlin?

  It was wonderful. It's such a pleasure to speak to you, and thank you for joining us. And if you'd like to learn more about your own perception box, spend some time this week answering the same perception box questions that we asked our guests. And check out other questions on our website at unlikelycollaborators.com. You can also subscribe to our YouTube channel, and watch the show, or listen wherever you get your podcasts. This has been Science of Perception Box, created by Unlikely Collaborators in partnership with Podpeople. I'm Dr. Heather Berlin.

• 25:56Speaker 02

  And I'm Dr. Kristoff Koch.

• 25:58Heather Berlin?

  Thank you.