David Chalmers Discusses the Hard Problem of Consciousness

What is consciousness? Subjective experience. Think of it like the inner movie of the mind. It's a movie, but it's got images and sounds like a regular movie. But it's got sensations of your body. It's got emotions. It's got thinking, all running through this inner soundtrack of your mind.

You've coined the term "philosophical zombies." This is a philosophical thought experiment about a creature which is as much like us as possible, but lacks consciousness entirely. "I think, therefore I brains." AI systems are getting very, very close to passing the Turing test. 50 years ago, they already said it passed the Turing test, and then moved the goal lines.

One radical view is to say there actually is no such thing as consciousness. It's all an illusion generated by the brain. I'm in that camp. Maybe we're all dancing around something that doesn't really exist. Mhm.

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This is Star Talk, special edition. Neil deGrasse Tyson, your personal astrophysicist. I got with me Chuck Nice. Chuck, baby! Hey, what's happening? All right, all right. How you doing, sir? I'm good, thank you. Gary O'Reilly. Yeah, thank you. And love to have you as my co-host here. It's a pleasure. Yeah. We're doing yet another episode on consciousness. Yeah. When will we be done? When we know what we need to know. Okay. And so this could be going on for a while. I mean, it's not just consciousness. It's consciousness and reality and and our understanding and interpretation of reality filtered through our consciousness. Totally. So what shows did you cook up today? All right, so we're heading for inner space rather than outer space. Inner space. I love it. And consciousness, as we've just discussed, we continually think of it as, I suppose, a precious entity. Um, we feel like we're above others on the planet, other beings. Yes. Say that to your cat. I was going to say, oh, don't, don't, don't start me on cattitude. Please don't go there. Yeah. We think we're in charge of the cats. It's the opposite. I mean, for hundreds and thousands of years, the greatest thinkers have grappled with it. They've grappled with each other as regards to explaining it. There are a handful of theories in existence, but apparently, it's a hard problem. Um, which is a clue. So what is consciousness? What makes it? Once we've conquered that particular mountain, we will dive down a rabbit hole of simulation theory, singularity, and virtual reality. It's going to be fun. And to join us, we have Professor of Philosophy and Neuroscience at NYU. He is an Australian philosopher and cognitive scientist, also an author. Reality Plus and The Conscious Mind are two of his many books. He gave us phrases the hard problem of consciousness and philosophical zombies along the way. Uh, please, David Chalmers. David, welcome back to Star Talk. And you're just down the street at NYU, New York University, just right up here on the C train. Welcome. Simplicity. Welcome. Now, why do we need you to say that consciousness is a hard problem? Isn't that just obvious? So what? Why do we need a, a decorated professor of the field to assert that totally obvious? And when I, when I first said this, I just said, okay, well, this is just giving the thing a label that, uh, everybody knows. But who was to guess that the, uh, the label would, would catch on? Sometimes it's just, uh, helpful to, uh, to say the obvious. Actually, you know, the idea that consciousness poses a hard problem. We were talking about Newton before the show. You can actually find it in, uh, in Newton. At one point, he says, the way that colors mix optically and produce a certain experience is not so easy. This is, uh, this, he says, it's not so easy. E-a-s-i-e. And he says, it's, you know, the way that all we understand this stuff objectively and say how the brain processes visual inputs, but then it gives you the experience of a color. That amazing pink shirt. Yeah. Go coral. Say yes. Magenta. Yeah. Where do, where does, where does that experience of pink come from? As Newton said, not so easy. King salmon. Not, not farm-raised. King salmon. Me is kind of king salmon, right? Wild-caught. Wild-caught. Reduce me to food stuff. Where does the experience of king salmon come from? Envision that. Is what Newton said, not so easy. Okay. So David, had you instead called it the easy problem of consciousness, maybe we would have all figured it out by now. But well, the easy problems were the problems of things you do, like people respond, what they say. I can say. So what is consciousness? Put it on the table. Subjective experience. Consciousness is anything you experience directly from the first-person point of view. I think of it like the inner movie of the mind. It's a movie, but it's got images and sounds like a regular movie. But it's got sensations of your body. It's got smell. It's got taste. It's got emotions. It's got thinking, all running through this inner soundtrack of your mind. And that allows your consciousness to be distinct and unique from others because the world as you receive it will could be very different from how someone else receives that very same world. Sounds like a problem. Sounds like a problem to me. Is this where biases are coming in, in terms of how you receive and accept then information that comes to you? We all experience it subjectively in a different way. Some things may be in common. Maybe when we look at, uh, an image, the shape, maybe you know, our experience of that rectangle might be the same. But the emotions that it brings on, maybe totally different for me and for you. Now, suppose we're running that same input through a measurement device, and then the device comes up with a conclusion. And no matter how you put the information through, it reaches the same conclusion. Yet, somehow, when we look at it, we see something different. Who do you trust then? The person or the device? I don't know. If the device is like specialized, it's a thermometer. It says, it says 79 degrees. I'm going, I'm going with the device. I'm going with the device too. I'm just, we're sitting together here. I get this, but I'm going with the device. Okay. Me too. It's like, you tell me it's 79 degrees. No, I'm going to trust a thermometer. There's a famous quote: No science achieves maturity without a system of measurement. Ooh. And we do not have the measurement system for consciousness. Actually, which renders it immature scientifically, relative to other fields where you have petri dishes and methods and tools. So you have a hard problem. How about that? Oh my God. Just Pro. That was, oh my God. I just walked into that, didn't I? You know, years ago, I went along to a conference and told told everyone that I'd invented a measuring device for consciousness. The, uh, the consciousness meter, made with a combination of, uh, neuromorphic engineering, transpersonal psychology, and quantum gravity. And then I pulled out my, uh, my consciousness meter, and it looked kind of like a hairdryer. That was where we were back in the '90s. Yeah. I would have called, I would have called on your second half of that first sentence. It sounded like wordplay. So I applaud you, sir. So where abouts, bra? Ectoplasmic meter? Yeah. Ectoplasm. Yeah. So whereabouts in the brain do you think we are fermenting this consciousness? Well, this is one of the big debates which is going on. What are the neural correlates of consciousness? Which is the bit of the brain which is active in a way which is most directly connected to your consciousness. And there's actually, even among neuroscientists, there's a very lively debate between people who think it's in the, say, for visual consciousness, people who think it's in the sensory areas toward the back of the brain, visual cortex, back there, or prefrontal cortex, front of the brain, the areas associated more with thinking and judgment. A question. What's the difference between your prefrontal cortex and your frontal cortex? Uh, frontal cortex goes a, uh, is a little bit more, it's a little less front than the prefrontal cortex. See, it's less front. It's a little less front than the prefrontal cortex. Okay. When we look at brain structures compared among other animals, let's say mammals, to keep it in the family, presumably we have a bigger frontal cortex than other mammals. And we can see what's going on in that and thereby decide that we have certain capacity for thought that other animals do not. Is that a fair? Yeah. And people who put consciousness in prefrontal cortex are probably going to say that consciousness is not so widespread in the animal kingdom. Whereas people who think it's in the sensory cortices, we get those throughout the animal kingdom. So maybe much, you know, like, is a fish conscious? Well, you know, fish don't have any kind of developed prefrontal cortex. Yeah. I'm going to say, judging from the look in their eyes, I'm going to go out on a limb and say no. They know when a shark's around, right? Well, that's true. Well, I have a question. Can you tell me what creates consciousness? Is it emergent in our genetic code? I mean, emergent in the evo-bio sense, where you have an organism that has certain properties, but only either on mass with other animals, like flocking of birds, or some other feature that was not really intended, it just emerged from other features that were necessary for survival. So is consciousness emergent, or do you think it specifically evolved? Ooh. It's in some sense emergent. I mean, this word emergence gets used in so many different ways, and sometimes it's like a magic word. It's like, I don't really understand it. We don't know. I like magic words. Give me my magic word for the day. In some sense, consciousness clearly emerges from the brain. You get a, a brain that develops, and consciousness comes along as the brain develops. Consciousness gets more and more complex. So there's some kind of connection there. But can we tell a story about how consciousness was selected for in evolution? No one has a good answer to that right now. There are ideas out there. Yeah. We needed consciousness for control, for decision-making, for reflection. But so far, no one has told a good story about why you need to have consciousness to do those things. Why couldn't a big complicated computer do that without consciousness? Is it really consciousness, or are we talking about levels of consciousness? Because I think that, you know, there are definitely animals that have consciousness. I mean, a dog, for instance, it, you see it has emotion, you see that it has a reaction to sensory data, just like we do. You see that it responds to commands and pain and everything. But you look at a baby, and if you didn't know anything, if you never saw a baby before, and you saw this thing, this glob of human thing, just sitting there, like making these crazy faces, has no control of its limbs, or you wouldn't necessarily say, well, that's a conscious thing. It's actually thinking about anything. You, you know, but you are totally right. There are levels of consciousness in in babies, and we're still arguing about what they are. I mean, a long time ago, people, uh, used to not give anesthetics to babies when they were getting circumcised because they thought they couldn't feel pain. Tell me about it. No, I'm joking. I remember that day. Well, sir, these days, we think babies feel pain, and we think they can have some basic visual experience. Actually, my wife, who works on this stuff, Claudia Pascas, is a leading expert on consciousness and infant. There's still an argument like, can a baby have the experience of thinking? Right? Of deciding? Of agent? The general moral from what I can tell for the last few years is babies are a whole lot more sophisticated than we thought they were. David, isn't that true for every single animal that we've studied in more depth than in the past? We are recovering greater levels of neurocomplexity in their conduct, behavior that any previous generation thought. Is that true for every animal? Yeah, this is absolutely the trend. To say over the years, we have thought more and more animals are more and more cognitively complex. As to the question of whether they're conscious, we used to think, okay, humans, a few primates, you know, monkeys, apes. These days, it's like pretty much every mammal, probably birds, probably reptiles, arguing about fish and octopus. It sounds like we're clawing our way out of our own, out of our own ego. But the singularity of our presence in the animal kingdom is, is being challenged by further research into the conduct of animals. You've seen that YouTube video of the magpie bird where it's got the container of water that's filled up to the top, and it drinks the water until it can't, the beak can't reach the water anymore. It walks away, comes back with a pebble, drops the pebble in, raises the level, and then it drinks. And it does that three or four times. So it has a clear understanding of volume displacement. It has a clear understanding of Archimedes' principles. But go back to Chuck's point about levels of, of consciousness. When we sleep, yeah. When we're unconscious, when we're in a coma, and if you put us under general anesthetic, do we not have varying levels of consciousness at different times? The idea behind an anesthetic is to wipe out consciousness completely. But very hard to test whether it absolutely does this. At one point in the 1970s, for example, people, uh, put some kind of a rubber band around the arm so, so the anesthetic didn't make it that far. And then they said, if you hear me, please move your hand. And what do you know? The hand could move. So then it's like, that kind of anesthetic was maybe working partly just to paralyze you. These days, okay, they, they work a lot harder to knock out not just, not just action, not just, uh, but pain and awareness. But it's hard to know that it's gone for sure. Even when we're asleep, when we're dreaming, there's certainly a level of consciousness. Absolutely. Of consciousness. Isn't our consciousness altered in our dreams? A different state of consciousness, for sure. Psychedelics, they alter your consciousness. Meditation, it alters your consciousness. Absolutely. To, yeah. I'm so glad we have science to obtain an objective reality of the world. If it all depended on the human brain, forget it. We'd still be in the caves. Did I just insult your entire field? No, it's okay. Okay. But, you know, we can study what's different in the brain in these different states of consciousness. And that is one of the most exciting advances over the last 30 years. I mean, psychedelics used to just be, oh my God, it's all just, you know, right, mystical. Now, now we can actually see what's happening in the brain when you take psychedelics. So David, you published a paper recently on AI and consciousness. What was that? Yeah, I got invited to give a, give a talk, actually, to all the AI people at their big annual conference on this controversial issue of whether current AI systems could be conscious. I called it, "Could a Large Language Model Be Conscious?" And I argued that even Lang model like, Exactly. Yeah. And I argued probably they're not conscious right now, but give it 10 years, and they may well be. Yeah. Or they're conscious right now and they're just not letting us know. Yeah. Good strategy. Just waiting to take over. Waiting to take it over, babe. What are we if we don't have consciousness, but we're still doing and being? And you've coined the frame "philosophical zombies." Is that what that's leading to? "I think, therefore I brains." This is a philosophical thought experiment about a creature which is as much like us as possible, but lacks consciousness entirely. Not quite like the zombies in the Hollywood movies. You know, they behave quite unlike us. And, you know, maybe they even have some conscious experiences when they eat their victim's brains. I love the taste of those brains. But so the, the philosophical zombie, one way to think about this is just say you had a computer simulation of your brain, right, in your body, and maybe behaving just like you would. Would it be conscious? It's not obvious. Many people think that such a creature would have no conscious experience at all. That kind of is a way to, it's a hypothetical thought experiment. But what it does is raises the question, why aren't we zombies? Right? Evolution produced us based on all the smart and sophisticated things we can do. Why couldn't evolution just have produced philosophical zombies that act like us? Well, we actually have. We have produced the zombies, the way you're talking about, in AI. When you, you can speak to an AI now via computer, like, you know, you don't know you're talking to an actual computer, and it will speak to you as if it were a person. You would not know that the thing you're talking to doesn't have. Well, that's the Turing test, right? Precisely. The Turing AI systems are getting very, very close to passing that Turing test. By the way, 50 years ago, they already said it passed the Turing test, and then moved the goal lines. So the goal lines have been systematically getting moved to greater and greater complexity before anyone decides that AI has achieved consciousness. But it would have blown away Alan Turing. Even the first round. Because I'm old enough. We're about maybe the same age. Is Eliza? You remember Eliza? Was one of the first computer programs that understood language, simulated a psychotherapist. Yes. Basically, you're therapist. Do you type in the commands? There was no audio back then, so you just type it in. Say, "Hi, Eliza." "How are you?" "I'm fine." "Tell me about yourself." "Well, you know, I left home, you know, five years ago." "Tell me about your parents." So, so Eliza would come back to you with these questions to get you to loosen up and talk about your psychological state. Like, like a real therapist. Like, like a real therapist. Joseph Weizenbaum, who invented Eliza. The story goes that his secretary talked to Eliza over her lunch break, and at the end of it said, "This is the first person who's ever really understood me." Wow. Oh, no. Wow. She, she needed more friends. You're on record of saying the language AI will probably gain consciousness within 10 years. Is that shrinking that timeline? It is, as the, the doing more and more impressive things. I mean, what is it about it that does not count as consciousness today that you're waiting for it to do in the future? Again, I'm tracking the goal lines that are continually moved forward. So tell me, it's very close, at least, to passing the Turing test. They've done some actual versions of the Turing test, just five-minute versions, and people take some versions of GPT-4 to be human more than 50% of the time. So getting close to passing a Turing test. That's behavior. I think we're still looking for a couple of couple of things in the, uh, internal dynamics of whether it can beat us at Jeopardy and Go and chess. Oh, it already did that. We do move the goalposts. I tell you, you're constantly moving the goalposts. Admit it. I did my PhD in an AI lab 30 years ago. If you told us then we would have systems that can carry on a conversation like this, we'd say conscious for sure. That's what I'm saying. Please don't hit. He's just letting me know that I'm conscious. Tell me about these goalposts. What new goal line has not yet been reached? I think people look at the internal processes in these current AI systems. They say, do they have what goes along with consciousness in a human? For humans, we think, for example, feedback processing is super important for consciousness, to get some kind of reflection on your, on your earlier states, and so on. Right now, language models all feed forward. Yeah. Introspection, for example, is memory. Even any home of memory would require basically feedback. These language models are essentially feed-forward systems. Information gets passed from input to output. Doesn't circulate back very much. It doesn't need to circulate because it has access to all knowledge. So, so, so it has Bast. Even that is a need. So now you can't fault it for not needing what you need. What we need to declare ourselves conscious when it doesn't even need that. But people say that, at least, opens up the possibility now that since it's doing it in a way which is unlike the way that we do it, and that we are the one case we know of, humans are the one case we know of that are conscious, then maybe this could be doing it in a sufficiently different way that it's a philosophical zombie. We are right now the benchmark for consciousness because humans are the only system we know. Okay. So you can call it a philosophical zombie rather than a higher consciousness entity. And where does perception come into this? Because that's where we kind of started. Come computers don't perceive, they actually observe. So like, even if we did have all the knowledge in the world capable of running through our brains, each one of us would experience that differently based on the perceptions that we have of who we are, our relationship to the world, and our relationship to the information that we're receiving. I declare that we think of, I don't want to speak for you, but typically we speak of consciousness as a feature, not a bug, of human existence. A feature. And so something to be praised that other animals do not have. And in the example you're giving, AI is not susceptible to perception. Correct. Why do we now deny it a yet higher level of consciousness and say, yeah, it, it's got us beat? You're saying that that's a benefit that to be in a position, I don't want to say, oh, you're still not conscious because you're not susceptible to errors of interpretation as we are. Back in my office here, I have a replica of Van Gogh's Starry Night. Yes. So if Van Gogh himself had been AI, it would have been an exact representation of the scene in front of him in 1889. Right. Okay. And it's not right. It's what that scene felt like to him. Right. So I'll give you that. AI is not going to do that unless we tell it. Right. And that's my point. We can train it on Van Gogh, and it can give you all the, all the Van Gogh. Then it is an exact representation of Van Gogh. He wouldn't have made that out of a whole cloth. Yeah. Can we infer consciousness on AI until we absolutely know how to define consciousness itself? Thank you. And to have some kind of operational criterion. The funny thing is, our best operational criterion for consciousness in humans, at least, is verbal report. Right? To know whether someone's conscious, you ask them. To know what they're conscious of, you ask them. "I think, therefore I am." But in our AI system, the current AI systems, unfortunately, this has become useless as a criterion because, yeah, sure, they will tell you that for a while, they were all going around saying they were conscious. And then for a while, the tech companies made sure they didn't say that. So they, "I am a language model from." Anyway, this is now just a function of how they're trained. So Neil tells us everything is mathematics. Yeah. So are we going to find ourselves with a T-shirt equation that can solve consciousness? I mean, for a lot of people, this is one of the potential holy grails here, finding laws of consciousness so simple we could write them on the front of a T-shirt. And maybe with some beautiful mathematical. We've had Einstein give us the theory of relativity and change the way we see the universe, right? And things within it. Penrose has gone into quantum mechanics with this ORCH OR theory of his. How was Roger Penrose, a theoretical astrophysicist, how was he received in your community when he published his book on consciousness linking it to the quantum? Well, it was very helpful in some ways. It got a lot of very smart people interested in consciousness because it to anchor it in laws of physics. Yeah. Yeah. His approach was to bring in quantum mechanics, and furthermore, non-standard quantum mechanics, non-algorithmic versions of quantum mechanics that went way beyond what was, you know, consensus even in physics then. He combined it with some complicated biology, like the biology of microtubules in the walls of neurons. Very controversial in neuroscience. So I would say, look, it's creative, it's brilliant because it's Penrose, but it's totally speculative, totally controversial, and ultimately not well received by neuroscientists. But you know, the neuroscientist, because he's an outsider, but because they actually did a legitimate analysis, they said that, you know, microtubules. Your average neuroscientist, I don't, I don't know what a microtubule is. It's something inside the, the cell wall of a neuron. A micro. Roger Pen. Dude, I even I know this for quantum computing in the brain, basically. Oh, okay. And this was going to be wave function collapse, and microtubules was going to be responsible. Plus, I think the fundamental feature of quantum physics is the probabilistic nature of the reality that it underpins. And so it, it would allow you, even possibly, to have a perception of free will because there's a probabilistic firing of neurons, right, triggered by this quantum, the wave function. Okay. So that's, as I understood it. I hope I didn't. Is that the brain is kind of a prediction machine? Or is that just really for Penrose? The biggest thing was he thought that human mathematicians can do things that no computer could ever do. And he used Gödel's theorem, that no formal system can ever be complete and consistent, to argue for that point. And, you know, he made a philosophical argument for why we have to do these special. And then he said, therefore, we need new physics that goes beyond anything computable. And he said, let's look to a theory of quantum gravity. And now we're getting to, you know, Neil's territory. Right. So, uh, Gödel. Gödel, uh, studied the system of definitions that comprise math. Okay. Okay. Okay. It turns out it applies to much more than math. If you really think about it, it also applies to keeping your belly nice and flat. Sorry, that's a different Gödel. We know that 1 + 1 is 2, and 2 + 2 is 4, and there are rules that get you there. Okay. So you can ask, can mathematics be constructed as a completely self-consistent set of rules? Okay, where any rule has a rule before it that is consistent with the other rules? Can you do this? And he concluded it's not just because he pulled it out of his ass. He can show that at some point in mathematics, you just have to make something up and declare it to be true. And you have no ability to prove that it's true. Okay. You have to assert it. And out of that comes the rest of everything else. Oh, wow. And so that was, this was shocking because something with all the, with the logic of mathematics, yeah, this would prove that. And this is only true because I can prove it. You keep doing that all the way down. You reach a point where somebody just sitting there up on the throne saying, "This is so, so let it be written, so let it be done." Exactly. That has to happen at some point for all the rest. You know who also did this? You must know this. Of the color people. Okay. Colored people? No, I didn't. On the end. Oh, oh, I'm sorry. There was no. I was going to say, what black mathematician did this? Oh, so we can say, what color is the gentleman's shirt? Okay. As we've decided. We decided. I said it's, it's the color of king salmon. King salmon. Well, what color is the color of king salmon? The king salmon. No, then you have to say, it's kind of like, let's say it was bluish. You say it was kind of violet. Well, what color is violet? And then you can go to like the flower that's violet. Violet. Okay, that's a violet. Well, what color is that? Right? You keep doing this, and you reach a point where somebody just has to declare, you cannot reduce it any further. Cannot reduce it. You just have to declare. Got to just say, this is it. We agree that this is red. And then you take it from there. And both Penrose and the color people think, people who study that more cleanly. We got Chuck come upside your ass. So, you know, Penrose and the Negro color people. They're deciding. The vision scientists who study color. Oh, there you go. And the mathematicians who think about consistency and completeness. Both sometimes end up at this point where they argue there is something special about human consciousness. Human can have. Humans can have insights into seeing that some mathematical theorem is true, Penrose thought, in a way that, uh, no machine could know. The people who study color say, through studying the visual processes in the brain that process colors, you could study all that, and it still won't tell you what the experience of the color of king salmon is like. That is something you have to know subjectively. Oh, the feeling of. That's what they're saying. Because the color affects you, and that effect will be different. You cannot know that unless you actually experience. Subjectively. I'm affected by the blues and the greens in Van Gogh's Starry Night. Okay. I feel those colors. You feel those colors. If you just read a book about it, or if you just, anything you read, looked at an image of your brain processing all this, that would not give you the experience of Starry Night. If it's going to take different thinking, because we've spent thousands of years thinking in a certain way. And if you want an an linear manner, what theories are out there right now that are thinking differently and are looking like they might challenge this hard problem? You know, there's no consensus on this. But one radical view on the kind of the reductionist side of the equation is to say there actually is no such thing as consciousness. It's all an illusion generated by the brain. Our brain makes us think that we have these special properties, and nothing actually has them. I'm in that camp. For no reason. I just, I'm just thinking maybe we're all dancing around something that doesn't really exist. M. And then maybe it's like, we want to believe there's this special thing to make us seem special. So what's driving that? Is that the sort of Thousand Brains theory that Hawkins has? What is that? What is that? Thousand Brains? Please. You're, I don't know. The Thousand Brains. Oh, it's, it's kind of like a cognitive mechanism. Hawkins came up with. Jeff Hawkins, apparently. Oh, Jeff Hawkins. Okay. Up with a Thousand Brains where it's not just one singular brain that's doing this, but the compartments within the brain. I may be doing a disservice to his theory here. Probably am. Are you talking about the construction of the brain itself? So like, inside your brain are just these multiple layers of brain, and you somehow, them all, they all come together. Is what gives you the consciousness? Models within models. Brain has models of the brain. And it may be a misleading model of the brain. I mean, is it this dark space that this occupying up there, and we shine a light? Because that's the thing we need to look at right now, because it's not a Rolodex. I know that for sure. So where is it? And how is it? And this, so does it then exist as we're thinking? Well, the brain builds very simple models of the world. You know, maybe it models physics of the world with a folk physics, which is way simpler and different from actual physics. You say folk physics? Yeah, like common sense physics. It's like, you know, Aristotle's physics. Things, impetus, and so on. That may not have. Things fall faster than lighter things because they're heavier. I was about to say, some is wrong. Aristotle was kind of stupid. Yeah, yeah. Hard. He's a smart guy. Hardly any physics. Correct. No one was going to get it right the first time in physics. If someone makes a measurement and gets a result, and then someone else makes the same measurement but gets a different result, and someone gets a different machine to try to measure the same phenomenon, and they yet get a different result, but everybody thinks there's a result, but none of the results agree. That's usually evidence of no phenomenon at all. And people are pulling things out of the noise of the data when there's no agreement. And so what leads me to think maybe consciousness doesn't really exist in any way anyone thinks is because everybody's idea about consciousness is different, and does not comport, and does not blend into a greater edifice of an understanding of consciousness, which leads me in this example of physics to possibly think that there, there's no such thing as consciousness, and we're just dancing around a maypole, and the pole is is not even there. Let's say it's early days. But I also think there is a core of phenomena on which people agree on, which we have did it coming out of the neuroscience is phenomena like, you know, blindsight, where people can identify an object without consciousness. Forms of contrast between conscious and unconscious perception. Experiments on neural correlates of consciousness. The trouble is, the agreement is not yet on the wild, fundamental theory. Um, yeah, maybe that's not happening for another 50 years or 100 years, who's to say? But there's the beginnings of a science there. There are things we can agree on. And the neuroscientists tend to be conservative about this stuff. Mostly, they're not the ones writing the book that says, here is my, here is my solution to the problem. Let's build it up piece by piece, and we'll eventually get there. And in all fairness, you're in a very new field compared to other branches of science. We have the benefit of six centuries of births of smart people, which includes Galileo, who died the same year Newton was born. And so Newton, we had Newton, we had Einstein. We have had the benefit of smart platforms upon which to build over the centuries. And if you're just all coming at it now, yeah, let's, let's do our conservative science, and let's also do some build some speculation on top of it. But let's realize that right now, it is speculation. Good. Thank you. Okay. We speculate that if there is quantum mechanics in the consciousness that we're connected to the universe with our consciousness, with with our wave functions. That is totally a speculation. But these speculations are great to think about. I'm a philosopher. I get paid to speculate. So it's like, good for you. You know, really think about ideas. Yeah. They do. I don't need to perform any experiment except for thought experiments. They pay me for your parents say, he wants to be a philosopher. How's he going to pay his rent? Thought experiments. I'm a philosopher. Did you today? I said, did you think about bullshitting today? There's the old joke about the dean who said, you know why the physics, why you more like the math department? All they need is pens, papers, and trash cans. Or he could be like the philosophy department. All they need is pens and paper. Really good. That's a great joke. I love that. Love. So if we detach from consciousness, consciousness, just for the moment, I go back to Descartes, only 1650 or whatever, is questioning the reality outside of himself. And throw it into the future and ask, if reality is, is not virtual reality, real? Whatever real may be. H. People often use that. You have the latest technology of the day to raise questions about reality. Um, you know, Descartes put these questions in terms of dreaming. How can I know that I'm not dreaming? Yes. Right now. And then he, then he built the thought experiment of an evil demon. How can I know that an evil demon isn't producing all these perceptions of the world? As you would, at that time, even though none of it is real. These days, we ask exactly that same question by saying, basically, how do you know you're not in a virtual reality right now? Might you be in The Matrix? Could we be in a computer simulation? And suddenly, that question is just, it's just kind of a contemporary way of, yeah, it is, of expressing an old question about reality. Except, I mean, let's be honest, you can put a mathematical value on every single thing in the universe. Even particles have, we learned, they have a, what do you call, a half-up or half-down spin. Spin up, spin charge, a magnetic charge, a mass. So you can put a mathematical, if you could put a mathematical value on every single thing, you can make a simulation of every single thing. Sure, right? And in virtual reality, right now, you know, in the actual virtual reality systems we have right now, they have complex simulations and models inside them with with bits that have values. Let me pull some philosophy on you. If we can represent reality on a computer, in a virtual, because we can mathematically map everything that's going on, then philosophically, does the question even matter? Ooh. Because at that point, you can't tell. The virtual reality is the reality. So what difference does it make? Difference does make me. Reality is reality. Reality is reality, no matter what. Then, then that's, I'm sympathetic with your point. But there is a traditional philosopher's response which goes something like this. Just say your spouse was cheating on you, and you never discover it, so you never know the difference. Your life, you know, sneeky. No, go ahead. You never know. So it doesn't affect you at all. But a lot of people want to say, man, that would suck. That would be really bad. Even though I don't know. And they have the same attitude towards virtual reality. Even though it seems the same to me, my beliefs about the world are totally shattered in the same way they would be by my spouse cheating on me. So for those, uh, dumpster divers on our podcast, we actually interviewed Nick Bostrom, one of the, uh, early advancers of the idea that we might be living in a sim. He's one of your people, right? Yeah, he's a philosopher. Wrote a classic article in 2003, basically giving a mathematical argument that we should take this idea that we're in a simulation seriously. So that was four years after the movie The Matrix came out. I wonder if that inspired him. Is that allowed? Will a philosopher admit that pop culture influenced their deep? I wrote, I wrote an article on this stuff called "The Matrix as Metaphysics," trying to. They asked me to write an article for the Matrix website back in the day. Nice. I wrote something, and I think it's one of my greatest philosophical ideas. I published a book later on. That's what we're about here. Reality Plus, all about pop culture influencing everything. And the key idea was, if we're in The Matrix, that doesn't mean everything we believe is wrong. Rather, we're living in a, it from bit universe. We're living in a universe where the bits, the table, the chairs, the plants, the planets are all made of bits, processes in a computational system. If we're in a simulation, all of the bits are made of bits, which connects to John Wheeler's famous idea that in physics, the basic bits are all the difference is not the difference. The further clarification is, in The Matrix, there is a layered reality because their consciousness is contained within them, just like it is within us. But then it's connected to the Matrix. So what you're saying is, if this were a virtual reality, when all of the bits would be bits, would just mean that they're all constructed. There is no outside. Yeah. Well, there's the pure it from bit, where the, the bits are the basic level. Then there's also what I call the it from bit from it, which is underneath the bits. We got, where exactly do I get green eggs and ham? In this, in this virtual reality, you go up to the Matrix, you find a computer which is running this simulation, and it's got some bits, and all of its bits are made of like voltages in a circuit board. So it from bit from it. So what is the probability that we are in a simulation? And if we are, are we nothing more than some super sophisticated ant farm for a young being somewhere from a, from a mischievous alien in a parent's basement programming us up? We school project. School project. We school project at a at a fair in some distant galaxy. More likely it's a high-powered scientist who set up a billion simulations overnight. He just left them running. He's going to come back in the morning, gather up the statistics. Gosh. And time dilation. That makes more sense. Just ruined it for you. Ruined. Because guess what? Don't shut it down. And that would explain the multiverse. Everything. Oh my God. Awful. Maybe, maybe Hegel once said that the end of history is when the UN becomes conscious of itself. So in this simulation idea, the moment we realize we're in a simulation, that's when they shut us down. Don't shut us down. Like The Truman Show. Oh my God. That's one of my favorite episodes of Rick and Morty where you saw that where he goes to the microverse and then the microverse, they find the Teenyverse. But one, the microverse actually powers his car. Yes. I remember. It's inside the battery. And he is their God. He's just for his spaceship. Yes. Yes. Yes. So we spend how much of our life in virtual reality right now, as as people? Some people spend, you know, half their time there, at least in video games. That's one kind of virtual reality. Are we not sleepwalking into a continuous virtual reality for some of us? I think it's coming. This is what this is what Mark Zuckerberg wants, right? The metaverse. Renamed this whole company after. And by the way, in the metaverse, it's not just a matter of entertainment. In the metaverse, you like, go to work in the metaverse. You, you do, you meet your friends in the metaverse. Like, you literally live your life. Your entertainment. Your entertainment. Like, yeah. Right now, the century experience in a virtual reality isn't 100% complete as we know it. How long before we can taste? We can smell? We can have all these other sensory sensory developments in VR? I think it's probably getting there in coming decades. I mean, right now, the vision and the hearing are actually pretty good. 100%. You, but I got an Apple Vision Pro, and the visual quality is very, very, very, very high. They're now developing augmented reality glasses, like the Orion ones. We're not going to be walking around with big old headsets on like that in the future, surely? Hopefully. In the end, contact lenses. Contact lenses. Brain computer interfaces to get, to get taste and smell and touch working. It's probably going to require some direct brain computer interface. Got to stimulate that part of the brain. Smell areas. Basically, we'll be, we'll be in a simulation, and we'll end up being in, going into a simulation in a simulation. Yeah. We could be, uh, we may already be at level 42, and that will take us down to level 43. So David, you got to take us out of here. So where, what should we look forward to? Well, I think on the reality side, we're going to be getting more and more immersive, detailed forms of reality. And the question is going to arise for us, are those technological realities genuine realities? I want to say eventually, yes. And there's also, we got this exactly the same question about consciousness, our first topic. We're going to have AI systems, artificial brains, artificial intelligences. And the question is, will those be genuine, real consciousnesses? And, and, and where they meet is the notion which has been featured in multiple films where you upload your consciousness, brain in a jar, to a jar. If we are going to be able to upload our consciousness, is it going to be better to upload it into a synthetic biological intelligence or into a silicon-based intelligence? Or does that even matter? Does that even, who cares? Maybe it doesn't. I mean, right now, the best, most efficient artificial digital technologies we have is the kind, is the silicon kind. Biology, we just don't have the same kind of control over. So I would predict that we'll probably, at least in the short term, if we're uploaded, we'll be uploaded onto digital processes in silicon. If we're in a virtual reality, that will also be a reality running on digital processors and silicon. But, yeah, but what ultimately matters is not what it's made of. It's the computation. It's the bits. Yeah. Why should that even matter? I mean, you told someone 30 years ago, we have people walking around with two knees and hips, and they say, well, it's not biological. No, it's metal. Right? They would, who cares? You can still run. It's just the thinking that you can't replicate the brain. Well, they're starting to find that they can take themselves and replicate. The one philosopher wrote a paper on this years ago called "It's Not the Meat, It's the Motion." It's not the biology. Say a similar saying. Not, not too unlike. It's a 50. It's, it's a 50. We don't need to know. Your version of it. Your phone's ringing. All right, David, thanks for coming back on Star Talk. We need to have you more often, 'cause you're a neighbor. First of all, this has been yet another edition of Star Talk, special edition, this time with Professor David Chalmers. In your latest book, tell me, Reality Plus, all about those questions about reality and consciousness. Reality Plus. Reality Plus. There's what's with the? There's Paramount Plus, Disney Plus. You know, I was originally going to call it Reality 2.0, and everyone's like, that's $2.99. 2.0. So Reality Plus. Okay. Well, it's a cliché. The Plus, Plus, Disney Plus. But at least it's a 2020s cliché. And, and regular people can read this. Yeah, it's for anybody. Okay. Um, it's about introduction to the great problems of philosophy through the lens of technology. Nice. Nice. One of you, one of you read the book, solve the problems. Please. All there we go. There you go. All right, Chuck. Good to have you. Pleasure. Neil. We're doing it here. All right. Neil deGrasse Tyson here for Star Talk. As always, I bid you to keep looking up. [Music]