back to indexScott Aaronson: Computational Complexity and Consciousness | Lex Fridman Podcast #130
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The following is a conversation with Scott Aaronson, his second time on the podcast.
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He is a professor at UT Austin, director of the Quantum Information Center,
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and previously a professor at MIT. Last time we talked about quantum computing. This time
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we talk about computation complexity, consciousness, and theories of everything.
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I'm recording this intro, as you may be able to tell, in a very strange room in the middle of the
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night. I'm not really sure how I got here or how I'm going to get out, but Hunter S. Thompson
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saying I think applies to today and the last few days and actually the last couple of weeks.
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Life should not be a journey to the grave with the intention of arriving safely in a pretty and well
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preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally
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worn out, and loudly proclaiming, wow, what a ride. So I figured whatever I'm up to here,
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and yes, lots of wine is involved, I'm going to have to improvise, have to improvise,
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have to improvise, hence this recording. Okay, quick mention of each sponsor,
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followed by some thoughts related to the episode. First sponsor is SimpliSafe, a home security
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company I use to monitor and protect my apartment, though of course I'm always prepared with a fall
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back plan, as a man in this world must always be. Second sponsor is 8sleep, a mattress that cools
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itself, measures heart rate variability, has a nap, and has given me yet another reason to look
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forward to sleep, including the all important power nap. Third sponsor is ExpressVPN, the VPN
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I've used for many years to protect my privacy on the internet. Finally, the fourth sponsor is Better
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Help, online therapy when you want to face your demons with a licensed professional, not just
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by doing David Goggins like physical challenges like I seem to do on occasion. Please check out
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these sponsors in the description to get a discount and to support the podcast.
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As a side note, let me say that this is the second time I've recorded a conversation outdoors.
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The first one was with Steven Wolfram when it was actually sunny out, in this case it was raining,
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which is why I found a covered outdoor patio. But I learned a valuable lesson, which is that
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raindrops can be quite loud on the hard metal surface of a patio cover. I did my best with
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the audio, I hope it still sounds okay to you. I'm learning, always improving. In fact, as Scott says,
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if you always win, then you're probably doing something wrong. To be honest, I get pretty upset
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with myself when I fail, small or big, but I've learned that this feeling is priceless. It can be
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fuel, when channeled into concrete plans of how to improve. So if you enjoy this thing, subscribe
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on YouTube, review the Five Stars in Apple podcast, follow on Spotify, support on Patreon,
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or connect with me on Twitter at Lex Friedman. And now, here's my conversation with Scott Aaronson.
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Let's start with the most absurd question, but I've read you write some fascinating stuff about
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it, so let's go there. Are we living in a simulation? What difference does it make,
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Lex? I mean, I'm serious. What difference? Because if we are living in a simulation,
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it raises the question, how real does something have to be in simulation for it to be sufficiently
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immersive for us humans? But I mean, even in principle, how could we ever know if we were in
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one, right? A perfect simulation, by definition, is something that's indistinguishable from the
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real thing. Well, we didn't say anything about perfect. No, no, that's right. Well, if it was
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an imperfect simulation, if we could hack it, find a bug in it, then that would be one thing,
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right? If this was like The Matrix and there was a way for me to do flying kung fu moves or
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something by hacking the simulation, well then we would have to cross that bridge when we came to
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it, wouldn't we? At that point, it's hard to see the difference between that and just what people
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would ordinarily refer to as a world with miracles. What about from a different perspective, thinking
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about the universe as a computation, like a program running on a computer? That's kind of
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a neighboring concept. It is. It is an interesting and reasonably well defined question to ask,
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is the world computable? Does the world satisfy what we would call in CS the church touring
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thesis? That is, could we take any physical system and simulate it to any desired precision by a
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touring machine, given the appropriate input data, right? And so far, I think the indications are
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pretty strong that our world does seem to satisfy the church touring thesis. At least if it doesn't,
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then we haven't yet discovered why not. But now, does that mean that our universe is a simulation?
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Well, that word seems to suggest that there is some other larger universe in which it is running.
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And the problem there is that if the simulation is perfect, then we're never going to be able to get
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any direct evidence about that other universe. We will only be able to see the effects of the
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computation that is running in this universe. Well, let's imagine an analogy. Let's imagine
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a PC, a personal computer, a computer. Is it possible with the advent of artificial intelligence
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for the computer to look outside of itself to see, to understand its creator? I mean,
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that's a simple, is that a ridiculous analogy? Well, I mean, with the computers that we actually
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have, I mean, first of all, we all know that humans have done an imperfect job of enforcing
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the abstraction boundaries of computers, right? Like you may try to confine some program to a
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playpen, but as soon as there's one memory allocation error in the C program, then the
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program has gotten out of that playpen and it can do whatever it wants, right? This is how most hacks
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work, you know, viruses and worms and exploits. And, you know, you would have to imagine that an
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AI would be able to discover something like that. Now, you know, of course, if we could actually
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discover some exploit of reality itself, then, you know, then this whole, I mean, then in some
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sense we wouldn't have to philosophize about this, right? This would no longer be a metaphysical
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conversation. But the question is, what would that hack look like? Yeah, well, I have no idea. I mean,
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Peter Shor, you know, the very famous person in quantum computing, of course, has joked that
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maybe the reason why we haven't yet, you know, integrated general relativity in quantum mechanics
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is that, you know, the part of the universe that depends on both of them was actually left
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unspecified. And if we ever tried to do an experiment involving the singularity of a black
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hole or something like that, then, you know, the universe would just generate an overflow error or
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something, right? Yeah, we would just crash the universe. Now, you know, the universe, you know,
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has seemed to hold up pretty well for, you know, 14 billion years, right? So, you know, my, you know,
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a Occam's razor kind of guess has to be that, you know, it will continue to hold up, you know,
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that the fact that we don't know the laws of physics governing some phenomenon is not a strong
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sign that probing that phenomenon is going to crash the universe, right? But, you know, of course,
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I could be wrong. But do you think on the physics side of things, you know, there's been recently a
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few folks, Eric Weinstein and Stephen Wolfram that came out with a theory of everything. I think
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there's a history of physicists dreaming and working on the unification of all the laws of
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physics. Do you think it's possible that once we understand more physics, not necessarily the
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unification of the laws, but just understand physics more deeply at the fundamental level,
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we'll be able to start, you know, I mean, part of this is humorous, but looking to see if there's
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any bugs in the universe that could be exploited for, you know, traveling at not just speed of
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light, but just traveling faster than our current spaceships can travel, all that kind of stuff.
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Well, I mean, to travel faster than our current spaceships could travel, you wouldn't need to
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find any bug in the universe, right? The known laws of physics, you know, let us go much faster
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up to the speed of light, right? And, you know, when people want to go faster than the speed of
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light, well, we actually know something about what that would entail, namely that, you know,
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according to relativity, that seems to entail communication backwards in time. Okay, so then
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you have to worry about closed time like curves and all of that stuff. So, you know, in some sense,
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we sort of know the price that you have to pay for these things, right?
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But under the current understanding of physics.
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That's right. That's right. We can't, you know, say that they're impossible, but we, you know,
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we know that sort of a lot else in physics breaks, right? So, now regarding Eric Weinstein
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and Stephen Wolfram, like, I wouldn't say that either of them has a theory of everything. I
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would say that they have ideas that they hope, you know, could someday lead to a theory of everything.
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Is that a worthy pursuit?
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Well, I mean, certainly, let's say by theory of everything, you know, we don't literally mean a
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theory of cats and of baseball and, you know, but we just mean it in the more limited sense of
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everything, a fundamental theory of physics, right? Of all of the fundamental interactions of
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physics, of course, such a theory, even after we had it, you know, would leave the entire question
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of all the emergent behavior, right? You know, to be explored. So, it's only everything for a
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specific definition of everything. Okay, but in that sense, I would say, of course, that's worth
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pursuing. I mean, that is the entire program of fundamental physics, right? All of my friends who
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do quantum gravity, who do string theory, who do anything like that, that is what's motivating them.
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Yeah, it's funny, though, but, I mean, Eric Weinstein talks about this. It is, I don't know
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much about the physics world, but I know about the AI world, and it is a little, it is a little bit
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taboo to talk about AGI, for example, on the AI side. So, really, to talk about the big dream of
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the community, I would say, because it seems so far away, it's almost taboo to bring it up, because,
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you know, it's seen as the kind of people that dream about creating a truly superhuman level
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intelligence. That's really far out there, people, because we're not even close to that. And it feels
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like the same thing is true for the physics community. I mean, Stephen Hawking certainly
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talked constantly about theory of everything, right? You know, I mean, people, you know,
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use those terms who were, you know, some of the most respected people in the whole world of
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physics, right? But, I mean, I think that the distinction that I would make is that people
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might react badly if you use the term in a way that suggests that you, you know, thinking about
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it for five minutes, have come up with this major new insight about it, right? It's difficult. Stephen
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Hawking is not a great example, because I think you can do whatever the heck you want when you
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get to that level. And I certainly see, like, senior faculty, you know, that, you know, at that
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point, that's one of the nice things about getting older is you stop giving a damn. But
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community as a whole, they tend to roll their eyes very quickly at stuff that's outside the
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quote unquote mainstream. Well, let me put it this way. I mean, if you asked, you know,
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Ed Witten, let's say, who is, you know, you might consider the leader of the string community,
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and thus, you know, very, very mainstream, in a certain sense, but he would have no hesitation
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in saying, you know, of course, you know, they're looking for a, you know, you know, a unified
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description of nature of, you know, of general relativity of quantum mechanics of all the
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fundamental interactions of nature, right? Now, you know, whether people would call that a theory
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of everything, whether they would use that term, that might vary. You know, Lenny Susskind would
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definitely have no problem telling you that, you know, if that's what we want, right?
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TK For me, who loves human beings and psychology,
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it's kind of ridiculous to say a theory that unifies the laws of physics gets you to understand
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everything. I would say you're not even close to understanding everything.
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TK Yeah, right. I mean, the word everything is a little ambiguous here. And then people will get
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into debates about, you know, reductionism versus emergentism and blah, blah, blah. And so in not
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wanting to say theory of everything, people might just be trying to short circuit that debate and
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say, you know, look, you know, yes, we want a fundamental theory of, you know, the particles
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and interactions of nature.
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TK Let me bring up the next topic that people don't want to mention, although they're getting
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more comfortable with it, is consciousness. You mentioned that you have a talk on consciousness
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that I watched five minutes of, but the internet connection was really bad.
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TK Was this my talk about, you know, refuting the integrated information theory?
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TK Which was a particular account of consciousness that, yeah, I think one can just show it doesn't
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work. Much harder to say what does work.
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TK Let me ask, maybe it'd be nice to comment on, you talk about also like the semi hard problem
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of consciousness or like almost hard problem or kind of hard.
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TK Pretty hard problem, I think I call it.
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TK So maybe can you talk about that, their idea of the approach to modeling consciousness and
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why you don't find it convincing? What is it, first of all?
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TK Okay, well, so what I called the pretty hard problem of consciousness, this is my term,
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although many other people have said something equivalent to this, okay? But it's just, you know,
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the problem of, you know, giving an account of just which physical systems are conscious and
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which are not. Or, you know, if there are degrees of consciousness, then quantifying how conscious
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a given system is.
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TK Oh, awesome. So that's the pretty hard problem.
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TK Yeah, that's what I mean.
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TK That's it. I'm adopting it. I love it. That's a good ring to it.
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TK And so, you know, the infamous hard problem of consciousness is to explain how something
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like consciousness could arise at all, you know, in a material universe, right? Or, you know,
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why does it ever feel like anything to experience anything, right? And, you know, so I'm trying to
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distinguish from that problem, right? And say, you know, no, okay, I would merely settle for an
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account that could say, you know, is a fetus conscious? You know, if so, at which trimester?
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You know, is a dog conscious? You know, what about a frog, right?
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TK Or even as a precondition, you take that both these things are conscious,
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tell me which is more conscious.
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TK Yeah, for example, yes. Yeah, yeah. I mean, if consciousness is some multidimensional vector,
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well, just tell me in which respects these things are conscious and in which respect they aren't,
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right? And, you know, and have some principled way to do it where you're not, you know,
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carving out exceptions for things that you like or don't like, but could somehow take a description
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of an arbitrary physical system, and then just based on the physical properties of that system,
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or the informational properties, or how it's connected, or something like that,
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just in principle, calculate, you know, its degree of consciousness, right? I mean, this,
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this would be the kind of thing that we would need, you know, if we wanted to address questions,
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like, you know, what does it take for a machine to be conscious, right? Or when are, you know,
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when should we regard AIs as being conscious? So now this IIT, this integrated information theory,
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which has been put forward by Giulio Tinoni and a bunch of his
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collaborators over the last decade or two, this is noteworthy, I guess, as a direct attempt to
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answer that question, to, you know, answer the, to address the pretty hard problem,
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right? And they give a, a criterion that's just based on how a system is connected. So you,
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so it's up to you to sort of abstract the system, like a brain or a microchip, as a collection of
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components that are connected to each other by some pattern of connections, you know, and,
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and to specify how the components can influence each other, you know, like where the inputs go,
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you know, where they affect the outputs. But then once you've specified that,
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then they give this quantity that they call phi, you know, the Greek letter phi.
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And the definition of phi has actually changed over time. It changes from one paper to another,
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but in all of the variations, it involves something about what we in computer science
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would call graph expansion. So basically what this means is that they want, in order to get a
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large value of phi, it should not be possible to take your system and partition it into two
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components that are only weakly connected to each other. Okay. So whenever we take our system and
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sort of try to split it up into two, then there should be lots and lots of connections going
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between the two components. Okay. Well, I understand what that means on a graph.
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Do they formalize what, how to construct such a graph or data structure, whatever,
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or is this one of the criticism I've heard you kind of say is that a lot of the very interesting
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specifics are usually communicated through like natural language, like through words.
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So it's like the details aren't always clear. Well, it's true. I mean, they have nothing even
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resembling a derivation of this phi. Okay. So what they do is they state a whole bunch of postulates,
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you know, axioms that they think that consciousness should satisfy. And then there's some verbal
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discussion. And then at some point, phi appears. Right. Right. And this, this was what the first
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thing that really made the hair stand on my neck, to be honest, because they are acting as if there
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is a derivation. They're acting as if, you know, you're supposed to think that this is a derivation
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and there's nothing even remotely resembling a derivate. They just pull the phi out of a hat
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completely. Is one of the key criticisms to you is that details are missing or is there something
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more fundamental? That's not even the key criticism. That's just, that's just a side point.
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Okay. The, the core of it is that I think that the, you know, that they want to say that a system
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is more conscious the larger its value of phi. And I think that that is obvious nonsense. Okay. As
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soon as you think about it for like a minute, as soon as you think about it in terms of, could I
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construct a system that had an enormous value of phi, like, you know, even larger than the brain
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has, but that is just implementing an error correcting code, you know, doing nothing that we
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would associate with, you know, intelligence or consciousness or any of it. The answer is yes,
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it is easy to do that. Right. And so I wrote blog posts, just making this point that, yeah, it's
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easy to do that. Now, you know, Tinoni's response to that was actually kind of incredible, right?
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I mean, I, I, I admired it in a way because instead of disputing any of it, he just bit the
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bullet in the sense, you know, he was one of the, the, uh, the most, uh, uh, audacious bullet
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bitings I've ever seen in my career. Okay. He said, okay, then fine. You know, this system that
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just applies this error correcting code it's conscious, you know, and if it has a much larger
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value of phi than you or me, it's much more conscious than you and me. You know, you,
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we just have to accept what the theory says because, you know, science is not about confirming
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our intuitions. It's about challenging them. And, you know, this is what my theory predicts that
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this thing is conscious and, you know, or super duper conscious. And how are you going to prove
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me wrong? So the way I would argue against your blog posts is I would say, yes, sure. You're
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right in general, but for naturally arising systems developed through the process of evolution on
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earth, the, this rule of the larger fee being associated, being associated with more consciousness
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is correct. Yeah. So that's not what he said at all. Right. Right. Because he wants this to be
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completely general. So we can apply to even computers. Yeah. I mean, I mean, the, the whole
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interest of the theory is the, you know, the hope that it could be completely general apply to aliens,
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to computers, to animals, coma patients, to any of it. Right. And so, so, so he just said, well,
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you know, Scott is relying on his intuition, but, you know, I'm relying on this theory and,
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you know, to me it was almost like, you know, are we being serious here? Like, like, like,
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you know, like, like, okay, yes, in science we try to learn highly nonintuitive things,
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but what we do is we first test the theory on cases where we already know the answer. Right.
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Like if we, if someone had a new theory of temperature, right, then, you know, maybe we
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could check that it says that boiling water is hotter than ice. And then if it says that the sun
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is hotter than anything, you know, you've ever experienced, then maybe we, we trust that
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extrapolation. Right. But like this, this theory, like if, if, you know, it's now saying that, you
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know, a, a gigantic grit, like regular grid of exclusive or gates can be way more conscious than,
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you know, a person or than, than any animal can be, you know, even if it, you know, is, you know,
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is, is, is, is so uniform that it might as well just be a blank wall. Right. And, and so now the
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point is if, if this theory is sort of getting wrong, the question is a blank wall, you know,
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more conscious than a person, then I would say, what is, what is there for it to get right?
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So your, your sense is a blank wall is not more conscious than a human being.
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Yeah. I mean, I mean, I mean, you could say that I am taking that as one of my axioms.
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I'm saying, I'm saying that if, if a theory of consciousness is, is getting that wrong,
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then whatever it is talking about at that point, I, I, I'm not going to call it consciousness.
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I'm going to use a different word.
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You have to use a different word. I mean, it's also, it's possible just like with intelligence
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that us humans conveniently define these very difficult to understand concepts
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in a very human centric way. Just like the Turing test really seems to define intelligence as a
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thing that's human like. Right. But I would say that with any, uh, concept, you know, there's,
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uh, uh, uh, you know, like we, we, we, we first need to define it. Right. And a definition is
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only a good definition if it matches what we thought we were talking about prior to having
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a definition. Right. And I would say that, you know, uh, fee as a definition of consciousness
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fails that test. That is my argument. So, okay. So let's take a further step. So you mentioned
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that the universe might be a Turing machine. So like it might be computations or simulatable
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by one anyway, simulated by one. So what's your sense about consciousness? Do you think
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consciousness is computation that we don't need to go to any place outside of the computable universe
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to, uh, you know, to, to understand consciousness, to build consciousness, to measure consciousness,
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all those kinds of things? I don't know. These are what, uh, you know, have been called the,
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the vertiginous questions, right? There's the questions like, like, uh, you know,
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you get a feeling of vertigo and thinking about them. Right. I mean, I certainly feel like, uh,
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I am conscious in a way that is not reducible to computation, but why should you believe me?
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Right. I mean, and, and, and if you said the same to me, then why should I believe you?
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But as computer scientists, I feel like a computer could be, could achieve human level intelligence,
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but, and that's actually a feeling and a hope. That's not a scientific belief. It's just,
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we've built up enough intuition, the same kind of intuition you use in your blog.
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You know, that's what scientists do. They, I mean, some of it is a scientific method,
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but some of it is just damn good intuition. I don't have a good intuition about consciousness.
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Yeah. I'm not sure that anyone does or has in the, you know,
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2,500 years that these things have been discussed, Lex.
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But do you think we will? Like one of the, I've gotten a chance to attend,
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can't wait to hear your opinion on this, but attend the Neuralink event.
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And, uh, one of the dreams there is to, uh, you know, basically push neuroscience forward.
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And the hope with neuroscience is that, uh, we can inspect the machinery from which all this
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fun stuff emerges and see, we're going to notice something special, some special sauce from which
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something like consciousness or cognition emerges. Yeah. Well, it's clear that we've learned an
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enormous amount about neuroscience. We've learned an enormous amount about computation, you know,
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about machine learning, about AI, how to get it to work. We've learned, uh, an enormous amount about
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the underpinnings of the physical world, you know, and, you know, from one point of view,
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that's like, uh, an enormous distance that we've traveled along the road to understanding
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consciousness. From another point of view, you know, the distance still to be traveled on the
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road, you know, maybe seems no shorter than it was at the beginning. Right? So it's very hard to say.
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I mean, you know, these are questions like, like in, in, in sort of trying to have a theory
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of consciousness, there's sort of a problem where it feels like it's not just that we don't know
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how to make progress. It's that it's hard to specify what could even count as progress,
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right? Because no matter what scientific theory someone proposed, someone else could come along
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and say, well, you've just talked about the mechanism. You haven't said anything about
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what breathes fire into the mechanism, what really makes there something that it's like to be it.
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Right. And that seems like an objection that you could always raise no matter,
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you know, how much someone elucidated the details of how the brain works.
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Okay. Let's go to the Turing test and the Lobner Prize. I have this intuition, call me crazy,
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but we, that a machine to pass the Turing test and it's full, whatever the spirit of it is,
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we can talk about how to formulate the perfect Turing test, that that machine has to be conscious.
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We at least have to, I have a very low bar of what consciousness is. I tend to, I tend to think that
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the emulation of consciousness is as good as consciousness. So the consciousness is just a
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dance, a social, a social, a shortcut, like a nice, useful tool, but I tend to connect intelligence
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consciousness together. So by, by that, do you, maybe just to ask what, what role does consciousness
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play? Do you think it passed in the Turing test? Well, look, I mean, it's almost tautologically
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true that if we had a machine that passed the Turing test, then it would be emulating consciousness.
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Right? So if your position is that, you know, emulation of consciousness is consciousness,
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then so, you know, by, by definition, any machine that passed the Turing test would be conscious.
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But it's, but I mean, we know that you could say that, you know, that, that is just a way to
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rephrase the original question, you know, is an emulation of consciousness, you know, necessarily
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conscious. Right. And you can, can, you know, I hear, I'm not saying anything new that hasn't been
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debated ad nauseum in the literature. Okay. But, you know, you could imagine some very hard cases,
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like imagine a machine that passed the Turing test, but that did so just by an enormous
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cosmological sized lookup table that just cashed every possible conversation that could be had.
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The old Chinese room.
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Well, well, yeah, yeah. But, but this is, I mean, I mean, the Chinese room actually would be doing
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some computation, at least in Searle's version. Right. Here, I'm just talking about a table lookup.
link |
Okay. Now it's true that for conversations of a reasonable length, this, you know, lookup table
link |
would be so enormous that wouldn't even fit in the observable universe. Okay. But supposing that
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you could build a big enough lookup table and then just, you know, pass the Turing test just
link |
by looking up what the person said. Right. Are you going to regard that as conscious?
link |
Okay. Let me try to make this formal and then you can shut it down. I think that the emulation of
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something is that something, if there exists in that system, a black box that's full of mystery.
link |
So like, full of mystery to whom?
link |
To human specters.
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So does that mean that consciousness is relative to the observer? Like,
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could something be conscious for us, but not conscious for an alien that understood better
link |
what was happening inside the black box? Yes. So that if inside the black box is just a lookup
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table, the alien that saw that would say this is not conscious. To us, another way to phrase the
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black box is layers of abstraction, which make it very difficult to see to the actually underlying
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functionality of the system. And then we observe just the abstraction. And so it looks like magic
link |
to us. But once we understand the inner machinery, it stops being magic. And so like, that's a
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prerequisite is that you can't know how it works, or some part of it, because then there has to be
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in our human mind, entry point for the magic. So that's a formal definition of the system.
link |
Yeah, well, look, I mean, I explored a view in this essay I wrote called The Ghost in the Quantum
link |
Touring Machine seven years ago that is related to that, except that I did not want to have
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consciousness be relative to the observer, right? Because I think that if consciousness means
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anything, it is something that is experienced by the entity that is conscious, right? Like,
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I don't need you to tell me that I'm conscious, nor do you need me to tell you that you are,
link |
right? But basically, what I explored there is are there aspects of a system like a brain that just
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could not be predicted even with arbitrarily advanced future technologies? It's because of
link |
chaos combined with quantum mechanical uncertainty and things like that. I mean, that actually could
link |
be a property of the brain, you know, if true, that would distinguish it in a principled way,
link |
at least from any currently existing computer. Not from any possible computer, but yeah, yeah.
link |
This is a thought experiment. So if I gave you information that the entire history of your life,
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basically explain away free will with a lookup table, say that this was all predetermined,
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that everything you experienced has already been predetermined, wouldn't that take away
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your consciousness? Wouldn't you, yourself, wouldn't the experience of the world change for
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you in a way that you can't take back? Well, let me put it this way. If you could
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do like in a Greek tragedy where, you know, you would just write down a prediction for what I'm
link |
going to do and then maybe you put the prediction in a sealed box and maybe, you know, you open it
link |
later and you show that you knew everything I was going to do or, you know, of course,
link |
the even creepier version would be you tell me the prediction and then I try to falsify it,
link |
my very effort to falsify it makes it come true, right? Let's even forget that, you know,
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that version as convenient as it is for fiction writers, right? Let's just do the version where
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you put the prediction into a sealed envelope, okay? But if you could reliably predict everything
link |
that I was going to do, I'm not sure that that would destroy my sense of being conscious,
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but I think it really would destroy my sense of having free will, you know, and much, much more
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than any philosophical conversation could possibly do that, right? And so I think it becomes extremely
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interesting to ask, you know, could such predictions be done, you know, even in principle,
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is it consistent with the laws of physics to make such predictions, to get enough data about someone
link |
that you could actually generate such predictions without having to kill them in the process to,
link |
you know, slice their brain up into little slivers or something.
link |
I mean, it's theoretically possible, right?
link |
Well, I don't know. I mean, it might be possible, but only at the cost of destroying the person,
link |
right? I mean, it depends on how low you have to go in sort of the substrate. Like if there was
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a nice digital abstraction layer, if you could think of each neuron as a kind of transistor
link |
computing a digital function, then you could imagine some nanorobots that would go in and
link |
would just scan the state of each transistor, you know, of each neuron and then, you know, make a
link |
good enough copy, right? But if it was actually important to get down to the molecular or the
link |
atomic level, then, you know, eventually you would be up against quantum effects.
link |
You would be up against the unclonability of quantum states. So I think it's a question of
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how good of a replica, how good does the replica have to be before you're going to count it as
link |
actually a copy of you or as being able to predict your actions.
link |
That's a totally open question.
link |
Yeah, yeah, yeah. And especially once we say that, well, look, maybe there's no way to,
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you know, to make a deterministic prediction because, you know, we know that there's noise
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buffeting the brain around, presumably even quantum mechanical uncertainty,
link |
you know, affecting the sodium ion channels, for example, whether they open or they close.
link |
You know, there's no reason why over a certain time scale that shouldn't be amplified, just like
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we imagine happens with the weather or with any other, you know, chaotic system. So if that stuff
link |
is important, right, then we would say, well, you know, you can't, you know, you're never going to
link |
be able to make an accurate enough copy. But now the hard part is, well, what if someone can make
link |
a copy that sort of no one else can tell apart from you, right? It says the same kinds of things
link |
that you would have said, maybe not exactly the same things because we agree that there's noise,
link |
but it says the same kinds of things. And maybe you alone would say, no, I know that that's not
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me, you know, it's, it doesn't share my, I haven't felt my consciousness leap over to that other
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thing. I still feel it localized in this version, right? And then why should anyone else believe
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you? What are your thoughts? I'd be curious, you're a really good person to ask, which is
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Penrose's, Roger Penrose's work on consciousness, saying that there, you know, there is some,
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there's some, with axons and so on, there might be some biological places where quantum mechanics
link |
can come into play and through that create consciousness somehow.
link |
Yeah. Okay. Well, um, uh, of course, you know, I read Penrose's books as a teenager. They had
link |
a huge impact on me. Uh, uh, five or six years ago, I had the privilege to actually talk these
link |
things over with Penrose, you know, at some length at a conference in Minnesota. And, uh, you know,
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he is, uh, uh, you know, an amazing, uh, personality. I admire the fact that he was
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even raising such, uh, audacious questions at all. Uh, but you know, to, to, to answer your
link |
question, I think the first thing we need to get clear on is that he is not merely saying that
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quantum mechanics is relevant to consciousness, right? That would be like, um, you know, that would
link |
be tame compared to what he is saying, right? He is saying that, you know, even quantum mechanics
link |
is not good enough, right? If, because if, if supposing for example, that the brain were a
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quantum computer, I know that's still a computer, you know, in fact, a quantum computer can be
link |
simulated by an ordinary computer. It might merely need exponentially more time in order to do so,
link |
right? So that's simply not good enough for him. Okay. So what he wants is for the brain to be a
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quantum gravitational computer or, or, uh, uh, he wants the brain to be exploiting as yet unknown
link |
laws of quantum gravity. Okay. Which would, which would be uncomputable. That's the key point. Okay.
link |
Yes. Yes. That would be literally uncomputable. And I've asked him, you know, to clarify this,
link |
but uncomputable, even if you had an Oracle for the halting problem or, you know, and, and, or,
link |
you know, as high up as you want to go and the sort of high, the usual hierarchy of uncomputability,
link |
he wants to go beyond all of that. Okay. So, so, you know, just, just to be clear, like, you know,
link |
if we're keeping count of how many speculations, you know, there's probably like at least five or
link |
six of them, right? There's first of all, that there is some quantum gravity theory that would
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involve this kind of uncomputability, right? Most people who study quantum gravity would not agree
link |
with that. They would say that what we've learned, you know, what little we know about quantum
link |
gravity from the, this ADS CFT correspondence, for example, has been very much consistent with
link |
the broad idea of nature being computable, right? But, but all right, but, but supposing that he's
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right about that, then, you know, what most physicists would say is that whatever new
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phenomena there are in quantum gravity, you know, they might be relevant at the singularities of
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black holes. They might be relevant at the big bang. They are plainly not relevant to something
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like the brain, you know, that is operating at ordinary temperatures, you know, with ordinary
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chemistry and, you know, the, the, the physics underlying the brain, they, they would say that
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we have, you know, the fundamental physics of the brain, they would say that we've pretty much
link |
completely known for, for generations now, right? Because, you know, quantum field theory lets us
link |
sort of parameterize our ignorance, right? I mean, Sean Carroll has made this case and,
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you know, in great detail, right? That sort of whatever new effects are coming from quantum
link |
gravity, you know, they are sort of screened off by quantum field theory, right? And this is,
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this brings, you know, brings us to the whole idea of effective theories, right? But the,
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like we have, you know, the, in like in the standard model of elementary particles, right?
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We have a quantum field theory that seems totally adequate for all of the terrestrial phenomena,
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right? The only things that it doesn't, you know, explain are, well, first of all, you know,
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the details of gravity, if you were to probe it, like at, at, you know, extremes of, you know,
link |
curvature or like incredibly small distances, it doesn't explain dark matter. It doesn't explain
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black hole singularities, right? But these are all very exotic things, very, you know, far removed
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from our life on earth, right? So for Penrose to be right, he needs, you know, these phenomena to
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somehow affect the brain. He needs the brain to contain antennae that are sensitive to this as
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yet unknown physics, right? And then he needs a modification of quantum mechanics, okay? So he
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needs quantum mechanics to actually be wrong, okay? He needs, what he wants is what he calls
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an objective reduction mechanism or an objective collapse. So this is the idea that once quantum
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states get large enough, then they somehow spontaneously collapse, right? That, you know,
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and this is an idea that lots of people have explored. You know, there's something called the
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GRW proposal that tries to, you know, say something along those lines, you know, and these are
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theories that actually make testable predictions, right? Which is a nice feature that they have.
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But, you know, the very fact that they're testable may mean that in the, you know, in the coming
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decades, we may well be able to test these theories and show that they're wrong, right? You know, we
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may be able to test some of Penrose's ideas. If not, not his ideas about consciousness, but at
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least his ideas about an objective collapse of quantum states, right? And people have actually,
link |
like Dick Balmeister, have actually been working to try to do these experiments. They haven't been
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able to do it yet to test Penrose's proposal, okay? But Penrose would need more than just
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an objective collapse of quantum states, which would already be the biggest development in
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physics for a century since quantum mechanics itself, okay? He would need for consciousness
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to somehow be able to influence the direction of the collapse so that it wouldn't be completely
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random, but that, you know, your dispositions would somehow influence the quantum state
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to collapse more likely this way or that way, okay? Finally, Penrose, you know, says that all
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of this has to be true because of an argument that he makes based on Gödel's incompleteness theorem,
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okay? Now, like I would say the overwhelming majority of computer scientists and mathematicians
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who have thought about this, I don't think that Gödel's incompleteness theorem can do what he
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needs it to do here, right? I don't think that that argument is sound, okay? But that is, you know,
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that is sort of the tower that you have to ascend to if you're going to go where Penrose goes.
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And the intuition he uses with the incompleteness theorem is that basically
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that there's important stuff that's not computable? Is that where he takes it?
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It's not just that because, I mean, everyone agrees that there are problems that are uncomputable,
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right? That's a mathematical theorem, right? But what Penrose wants to say is that, you know,
link |
for example, there are statements, you know, given any formal system, you know, for doing math,
link |
right? There will be true statements of arithmetic that that formal system, you know,
link |
if it's adequate for math at all, if it's consistent and so on, will not be able to prove.
link |
A famous example being the statement that that system itself is consistent,
link |
right? No, you know, good formal system can actually prove its own consistency.
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That can only be done from a stronger formal system, which then can't prove its own consistency
link |
and so on forever, okay? That's Gödel's theorem. But now, why is that relevant to consciousness,
link |
right? Well, you know, I mean, the idea that it might have something to do with consciousness
link |
as an old one, Gödel himself apparently thought that it did. You know, Lucas thought so, I think,
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in the 60s. And Penrose is really just, you know, sort of updating what they and others had said.
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I mean, you know, the idea that Gödel's theorem could have something to do with consciousness was,
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you know, in 1950, when Alan Turing wrote his article about the Turing test, he already, you
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know, was writing about that as like an old and well known idea and as a wrong one that he wanted
link |
to dispense with. Okay, but the basic problem with this idea is, you know, Penrose wants to say
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that and all of his predecessors here, you know, want to say that, you know, even though, you know,
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this given formal system cannot prove its own consistency, we as humans sort of looking at it
link |
from the outside can just somehow see its consistency, right? And the, you know, the rejoinder
link |
to that, you know, from the very beginning has been, well, can we really? I mean, maybe, you
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know, maybe he, Penrose can, but, you know, can the rest of us, right? And, you know, I noticed
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that, you know, I mean, it is perfectly plausible to imagine a computer that could say, you know,
link |
it would not be limited to working within a single formal system, right? They could say,
link |
I am now going to adopt the hypothesis that my formal system is consistent, right? And I'm now
link |
going to see what can be done from that stronger vantage point and so on. And, you know, and I'm
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going to add new axioms to my system. Totally plausible. There's absolutely, Gödel's theorem
link |
has nothing to say about against an AI that could repeatedly add new axioms. All it says is that
link |
there is no absolute guarantee that when the AI adds new axioms that it will always be right.
link |
Okay. And, you know, and that's, of course, the point that Penrose pounces on,
link |
but the reply is obvious. And, you know, it's one that Alan Turing made 70 years ago. Namely,
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we don't have an absolute guarantee that we're right when we add a new axiom. We never have,
link |
and plausibly we never will. So on Alan Turing, you took part in the Lubna Prize?
link |
Not really. No, I didn't. I mean, there was this kind of ridiculous claim that was made
link |
some almost a decade ago about a chat bot called Eugene Goostman.
link |
I guess you didn't participate as a judge in the Lubna Prize.
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But you participated as a judge in that, I guess it was an exhibition event or something like that,
link |
Eugene Goostman, that was just me writing a blog post because some journalist called me to ask
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Did you ever chat with him? I thought that...
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I did chat with Eugene Goostman. I mean, it was available on the web.
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Oh, interesting. I didn't know that.
link |
So yeah. So all that happened was that a bunch of journalists started writing breathless articles
link |
about a first chat bot that passes the Turing test. And it was this thing called Eugene Goostman
link |
that was supposed to simulate a 13 year old boy. And apparently someone had done some test where
link |
people were less than perfect, let's say, distinguishing it from a human. And they said,
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well, if you look at Turing's paper and you look at the percentages that he talked about,
link |
then it seemed like we're past that threshold.
link |
And I had a different way to look at it instead of the legalistic way, like let's just try the
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actual thing out and let's see what it can do with questions like, is Mount Everest bigger
link |
than a shoebox? Or just like the most obvious questions. And the answer is, well, it just kind
link |
of parries you because it doesn't know what you're talking about.
link |
So just to clarify exactly in which way they're obvious. They're obvious in the sense that
link |
you convert the sentences into the meaning of the objects they represent and then do some basic
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obvious common sense reasoning with the objects that the sentences represent.
link |
Right. It was not able to answer or even intelligently respond to basic common sense
link |
questions. But let me say something stronger than that. There was a famous chatbot in the 60s
link |
called Eliza that managed to actually fool a lot of people. Or people would pour their hearts out
link |
into this Eliza because it simulated a therapist. And most of what it would do is it would just
link |
throw back at you whatever you said. And this turned out to be incredibly effective.
link |
Maybe therapists know this. This is one of their tricks. But it really had some people convinced.
link |
But this thing was just like, I think it was literally just a few hundred lines of Lisp code.
link |
It was not only was it not intelligent, it wasn't especially sophisticated. It was
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like a simple little hobbyist program. And Eugene Goostman, from what I could see,
link |
was not a significant advance compared to Eliza. And that was really the point I was making.
link |
In some sense, you didn't need a computer science professor to sort of say this. Anyone who was
link |
looking at it and who just had an ounce of sense could have said the same thing.
link |
But because these journalists were calling me, the first thing I said was,
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well, I'm a quantum computing person. I'm not an AI person. You shouldn't ask me. Then they said,
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look, you can go here and you can try it out. I said, all right. All right. So I'll try it out.
link |
This whole discussion, it got a whole lot more interesting in just the last few months.
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Yeah. I'd love to hear your thoughts about GPT3. In the last few months, the world has now seen
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a chat engine or a text engine, I should say, called GPT3. I think it still does not pass
link |
a Turing test. There are no real claims that it passes the Turing test. This comes out of the
link |
group at OpenAI, and they've been relatively careful in what they've claimed about the system.
link |
But I think as clearly as Eugene Goostman was not in advance over Eliza, it is equally clear that
link |
this is a major advance over Eliza or really over anything that the world has seen before.
link |
This is a text engine that can come up with kind of on topic, reasonable sounding completions to
link |
just about anything that you ask. You can ask it to write a poem about topic X in the style of poet
link |
Y and it will have a go at that. And it will do not a great job, not an amazing job, but a passable
link |
job. Definitely as good as, in many cases, I would say better than I would have done.
link |
You can ask it to write an essay, like a student essay, about pretty much any topic and it will
link |
get something that I am pretty sure would get at least a B minus in the most high school or
link |
even college classes. And in some sense, the way that it did this, the way that it achieves this,
link |
Scott Alexander of the much mourned blog, Slate Star Codex, had a wonderful way of putting it.
link |
He said that they basically just ground up the entire internet into a slurry.
link |
And to tell you the truth, I had wondered for a while why nobody had tried that. Why not write
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a chat bot by just doing deep learning over a corpus consisting of the entire web? And so
link |
now they finally have done that. And the results are very impressive. It's not clear that people
link |
can argue about whether this is truly a step toward general AI or not, but this is an amazing
link |
capability that we didn't have a few years ago. A few years ago, if you had told me that we would
link |
have it now, that would have surprised me. And I think that anyone who denies that is just not
link |
engaging with what's there. So their model, it takes a large part of the internet and compresses
link |
it in a small number of parameters relative to the size of the internet and is able to, without
link |
fine tuning, do a basic kind of a querying mechanism, just like you described where you
link |
specify a kind of poet and then you want to write a poem. And it somehow is able to do basically a
link |
lookup on the internet of relevant things. How else do you explain it?
link |
Well, okay. The training involved massive amounts of data from the internet and actually took
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lots and lots of computer power, lots of electricity. There are some very prosaic
link |
reasons why this wasn't done earlier. But it costs some tens of millions of dollars, I think.
link |
Less, but approximately like a few million dollars.
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Oh, okay. Oh, really? Okay.
link |
It's more like four or five.
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Oh, all right. All right. Thank you. I mean, as they scale it up, it will...
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It'll cost, but then the hope is cost comes down and all that kind of stuff.
link |
But basically, it is a neural net or what's now called a deep net,
link |
but they're basically the same thing. So it's a form of algorithm that people
link |
have known about for decades. But it is constantly trying to solve the problem,
link |
predict the next word. So it's just trying to predict what comes next. It's not trying to
link |
decide what it should say, what ought to be true. It's trying to predict what someone who had said
link |
all of the words up to the preceding one would say next.
link |
Although to push back on that, that's how it's trained.
link |
That's right. No, of course.
link |
It's arguable that our very cognition could be a mechanism as that simple.
link |
Oh, of course. Of course. I never said that it wasn't.
link |
Yeah. I mean, and sometimes that is... If there is a deep philosophical question that's
link |
raised by GPT3, then that is it, right? Are we doing anything other than this predictive
link |
processing, just trying to constantly trying to fill in a blank of what would come next
link |
after what we just said up to this point? Is that what I'm doing right now?
link |
It's impossible. So the intuition that a lot of people have, well, look,
link |
this thing is not going to be able to reason, the Mountain Everest question.
link |
Do you think it's possible that GPT5, 6, and 7 would be able to, with this exact same process,
link |
begin to do something that looks like... Is indistinguishable to us humans from reasoning?
link |
I mean, the truth is that we don't really know what the limits are, right?
link |
Because what we've seen so far is that GPT3 was basically the same thing as GPT2,
link |
but just with a much larger network, more training time, bigger training corpus,
link |
right? And it was very noticeably better than its immediate predecessor.
link |
So we don't know where you hit the ceiling here, right? I mean, that's the amazing part and maybe
link |
also the scary part, right? Now, my guess would be that at some point, there has to be diminishing
link |
returns. It can't be that simple, can it? Right? But I wish that I had more to base that guess on.
link |
Right. Yeah. I mean, some people say that there will be a limitation on the...
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We're going to hit a limit on the amount of data that's on the internet.
link |
Yes. Yeah. So sure. So there's certainly that limit. I mean, there's also...
link |
If you are looking for questions that will stump GPT3, you can come up with some without...
link |
Even getting it to learn how to balance parentheses, right? It doesn't do such a great job,
link |
right? And its failures are ironic, right? Like basic arithmetic, right?
link |
And you think, isn't that what computers are supposed to be best at? Isn't that where
link |
computers already had us beat a century ago? Right? And yet that's where GPT3 struggles,
link |
right? But it's amazing that it's almost like a young child in that way, right? But somehow,
link |
because it is just trying to predict what comes next, it doesn't know when it should stop doing
link |
that and start doing something very different, like some more exact logical reasoning, right?
link |
And so one is naturally led to guess that our brain sort of has some element of predictive
link |
processing, but that it's coupled to other mechanisms, right? That it's coupled to,
link |
first of all, visual reasoning, which GPT3 also doesn't have any of, right?
link |
Although there's some demonstration that there's a lot of promise there using...
link |
Oh yeah, it can complete images. That's right.
link |
And using exact same kind of transformer mechanisms to like watch videos on YouTube.
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And so the same self supervised mechanism to be able to look,
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it'd be fascinating to think what kind of completions you could do.
link |
Oh yeah, no, absolutely. Although like if we ask it to like, you know,
link |
a word problem that involve reasoning about the locations of things in space,
link |
I don't think it does such a great job on those, right? To take an example. And so
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the guess would be, well, you know, humans have a lot of predictive processing,
link |
a lot of just filling in the blanks, but we also have these other mechanisms that we can
link |
couple to, or that we can sort of call as subroutines when we need to.
link |
And that maybe, you know, to go further, that one would want to integrate other forms of reasoning.
link |
Let me go on another topic that is amazing, which is complexity.
link |
And then start with the most absurdly romantic question of what's the most beautiful idea in
link |
computer science or theoretical computer science to you? Like what just early on in your life,
link |
or in general, have captivated you and just grabbed you?
link |
I think I'm going to have to go with the idea of universality. You know,
link |
if you're really asking for the most beautiful. I mean, so universality is the idea that, you know,
link |
you put together a few simple operations, like in the case of Boolean logic, that might be the AND
link |
gate, the OR gate, the NOT gate, right? And then your first guess is, okay, this is a good start,
link |
but obviously, as I want to do more complicated things, I'm going to need more complicated building
link |
blocks to express that, right? And that was actually my guess when I first learned what
link |
programming was. I mean, when I was, you know, an adolescent and someone showed me Apple basic,
link |
and then, you know, GW basic, if anyone listening remembers that. Okay. But, you know,
link |
I thought, okay, well, now, you know, I mean, I thought I felt like this is a revelation. You know,
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it's like finding out where babies come from. It's like that level of, you know, why didn't
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anyone tell me this before, right? But I thought, okay, this is just the beginning. Now I know how
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to write a basic program, but, you know, really write an interesting program, like, you know,
link |
a video game, which had always been my dream as a kid to, you know, create my own Nintendo games,
link |
right? You know, but, you know, obviously I'm going to need to learn some way more complicated
link |
form of programming than that. Okay. But, you know, eventually I learned this incredible idea
link |
of universality. And that says that, no, you throw in a few rules and then you already have
link |
enough to express everything. Okay. So for example, the AND, the OR and the NOT gate can all,
link |
or in fact, even just the AND and the NOT gate, or even just the NAND gate, for example,
link |
is already enough to express any Boolean function on any number of bits. You just have to string
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together enough of them. You can build a universe with NAND gates. You can build the universe out of
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NAND gates. Yeah. You know, the simple instructions of BASIC are already enough, at least in principle,
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you know, if we ignore details like how much memory can be accessed and stuff like that,
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that is enough to express what could be expressed by any programming language whatsoever.
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And the way to prove that is very simple. We simply need to show that in BASIC or whatever,
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we could write an interpreter or a compiler for whatever other programming language we care about,
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like C or Java or whatever. And as soon as we had done that, then ipso facto, anything that's
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expressible in C or Java is also expressible in BASIC. Okay. And so this idea of universality,
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you know, goes back at least to Alan Turing in the 1930s when, you know, he
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wrote down this incredibly simple pared down model of a computer, the Turing machine, right,
link |
which, you know, he pared down the instruction set to just read a symbol, you know, write a symbol,
link |
move to the left, move to the right, halt, change your internal state, right? That's it. Okay.
link |
And anybody proved that, you know, this could simulate all kinds of other things, you know,
link |
and so in fact, today we would say, well, we would call it a Turing universal model of computation
link |
that is, you know, just as it has just the same expressive power that BASIC or Java or C++ or any
link |
of those other languages have because anything in those other languages could be compiled down
link |
to Turing machine. Now, Turing also proved a different related thing, which is that there is
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a single Turing machine that can simulate any other Turing machine if you just describe that
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other machine on its tape, right? And likewise, there is a single Turing machine that will run
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any C program, you know, if you just put it on its tape. That's a second meaning of universality.
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First of all, he couldn't visualize it and that was in the 30s.
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Yeah, the 30s. That's right.
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That's before computers really, I mean, I don't know how, I wonder what that felt like,
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you know, learning that there's no Santa Claus or something. Because I don't know if that's
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empowering or paralyzing because it doesn't give you any, it's like you can't write a software
link |
engineering book and make that the first chapter and say we're done.
link |
Well, I mean, right. I mean, in one sense, it was this enormous flattening of the universe.
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I had imagined that there was going to be some infinite hierarchy of more and more powerful
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programming languages, you know, and then I kicked myself for having such a stupid idea.
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But apparently, Gödel had had the same conjecture in the 30s.
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Oh, good. You're in good company.
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Yeah. And then Gödel read Turing's paper and he kicked himself and he said, yeah, I was completely
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wrong about that. But I had thought that maybe where I can contribute will be to invent a new
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more powerful programming language that lets you express things that could never be expressed in
link |
BASIC. And how would you do that? Obviously, you couldn't do it itself in BASIC. But there
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is this incredible flattening that happens once you learn what is universality. But then it's also
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an opportunity because it means once you know these rules, then the sky is the limit, right?
link |
Then you have kind of the same weapons at your disposal that the world's greatest programmer has.
link |
It's now all just a question of how you wield them.
link |
Right. Exactly. So every problem is solvable, but some problems are harder than others.
link |
Well, yeah, there's the question of how much time, you know, of how hard is it to write a program?
link |
And then there's also the questions of what resources does the program need? You know,
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how much time, how much memory? Those are much more complicated questions. Of course,
link |
ones that we're still struggling with today.
link |
Exactly. So you've, I don't know if you created Complexity Zoo or...
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I did create the Complexity Zoo.
link |
What is it? What's complexity?
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Oh, all right, all right, all right. Complexity theory is the study of sort of the
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inherent resources needed to solve computational problems, okay? So it's easiest to give an example.
link |
Like, let's say we want to add two numbers, right? If I want to add them, you know, if the numbers
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are twice as long, then it only, it will take me twice as long to add them, but only twice as long,
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right? It's no worse than that.
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For a computer or for a person. We're using pencil and paper, for that matter.
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If you have a good algorithm.
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Yeah, that's right. I mean, even if you just use the elementary school algorithm of just carrying,
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you know, then it takes time that is linear in the length of the numbers, right? Now,
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multiplication, if you use the elementary school algorithm, is harder because you have to multiply
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each digit of the first number by each digit of the second one. And then deal with all the
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carries. So that's what we call a quadratic time algorithm, right? If the numbers become twice as
link |
long, now you need four times as much time, okay? So now, as it turns out, people discovered much
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faster ways to multiply numbers using computers. And today we know how to multiply two numbers
link |
that are n digits long using a number of steps that's nearly linear in n. These are questions you
link |
can ask. But now, let's think about a different thing that people, you know, they've encountered
link |
in elementary school, factoring a number. Okay? Take a number and find its prime factors, right?
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And here, you know, if I give you a number with ten digits, I ask you for its prime factors.
link |
Well, maybe it's even, so you know that two is a factor. You know, maybe it ends in zero,
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so you know that ten is a factor, right? But, you know, other than a few obvious things like that,
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you know, if the prime factors are all very large, then it's not clear how you even get started,
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right? You know, it seems like you have to do an exhaustive search among an enormous number of
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factors. Now, and as many people might know, for better or worse, the security, you know,
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of most of the encryption that we currently use to protect the internet is based on the belief,
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and this is not a theorem, it's a belief, that factoring is an inherently hard problem
link |
for our computers. We do know algorithms that are better than just trial division, than just trying
link |
all the possible divisors, but they are still basically exponential. And exponential is hard.
link |
Yeah, exactly. So the fastest algorithms that anyone has discovered, at least publicly
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discovered, you know, I'm assuming that the NSA doesn't know something better,
link |
okay? But they take time that basically grows exponentially with the cube root of the size of
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the number that you're factoring, right? So that cube root, that's the part that takes all the
link |
cleverness, okay? But there's still an exponential. There's still an exponentiality there. But what
link |
that means is that, like, when people use a thousand bit keys for their cryptography,
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that can probably be broken using the resources of the NSA or the world's other intelligence
link |
agencies. You know, people have done analyses that say, you know, with a few hundred million
link |
dollars of computer power, they could totally do this. And if you look at the documents that Snowden
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released, you know, it looks a lot like they are doing that or something like that. It would kind
link |
of be surprising if they weren't, okay? But, you know, if that's true, then in some ways that's
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reassuring. Because if that's the best that they can do, then that would say that they can't break
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2,000 bit numbers, right? Then 2,000 bit numbers would be beyond what even they could do.
link |
They haven't found an efficient algorithm. That's where all the worries and the concerns of quantum
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computing came in, that there could be some kind of shortcut around that.
link |
Right. So complexity theory is a huge part of, let's say, the theoretical core of computer
link |
science. You know, it started in the 60s and 70s as, you know, sort of an autonomous field. So it
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was, you know, already, you know, I mean, you know, it was well developed even by the time that
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I was born, okay? But in 2002, I made a website called the Complexity Zoo, to answer your question,
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where I just tried to catalog the different complexity classes, which are classes of problems
link |
that are solvable with different kinds of resources, okay? So these are kind of, you know,
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you could think of complexity classes as like being almost to theoretical computer science,
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like what the elements are to chemistry, right? They're sort of, you know, there are our most
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basic objects in a certain way. I feel like the elements
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have a characteristic to them where you can't just add an infinite number.
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Well, you could, but beyond a certain point, they become unstable, right? Right. So it's like,
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you know, in theory, you can have atoms with, you know, and look, look, I mean, I mean,
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a neutron star, you know, is a nucleus with, you know, uncalled billions of neutrons in it,
link |
of hadrons in it, okay? But, you know, for sort of normal atoms, right, probably you can't get
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much above a hundred atomic weight, 150 or so, or sorry, sorry, I mean, beyond 150 or so protons
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without it, you know, very quickly fissioning. With complexity classes, well, yeah, you can have
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an infinity of complexity classes, but, you know, maybe there's only a finite number of them that
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are particularly interesting, right? Just like with anything else, you know, you care about
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some more than about others. So what kind of interesting classes are there? I mean,
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you could have just, maybe say, what are the, if you take any kind of computer science class,
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what are the classes you learn? Good. Let me tell you sort of the biggest ones,
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the ones that you would learn first. So, you know, first of all, there is P, that's what it's called,
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okay? It stands for polynomial time. And this is just the class of all of the problems that you
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could solve with a conventional computer, like your iPhone or your laptop, you know,
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by a completely deterministic algorithm, right? Using a number of steps that grows only like the
link |
size of the input raised to some fixed power, okay? So, if your algorithm is linear time,
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like, you know, for adding numbers, okay, that problem is in P. If you have an algorithm that's
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quadratic time, like the elementary school algorithm for multiplying two numbers, that's also
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in P, even if it was the size of the input to the 10th power or to the 50th power, well, that wouldn't
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be very good in practice. But, you know, formally, we would still count that, that would still be in
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P, okay? But if your algorithm takes exponential time, meaning like if every time I add one more
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data point to your input, if the time needed by the algorithm doubles, if you need time like two
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to the power of the amount of input data, then that we call an exponential time algorithm, okay?
link |
And that is not polynomial, okay? So, P is all of the problems that have some polynomial time
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algorithm, okay? So, that includes most of what we do with our computers on a day to day basis,
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you know, all the, you know, sorting, basic arithmetic, you know, whatever is going on in
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your email reader or in Angry Birds, okay? It's all in P. Then the next super important class
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is called NP. That stands for non deterministic polynomial, okay? It does not stand for not
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polynomial, which is a common confusion. But NP was basically all of the problems
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where if there is a solution, then it is easy to check the solution if someone shows it to you,
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okay? So, actually a perfect example of a problem in NP is factoring, the one I told you about
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before. Like if I gave you a number with thousands of digits and I told you that, you know, I asked
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you, does this have at least three non trivial divisors, right? That might be a super hard problem
link |
to solve, right? It might take you millions of years using any algorithm that's known, at least
link |
running on our existing computers, okay? But if I simply showed you the divisors, I said,
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here are three divisors of this number, then it would be very easy for you to ask your computer
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to just check each one and see if it works. Just divide it in, see if there's any remainder,
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right? And if they all go in, then you've checked. Well, I guess there were, right? So any problem
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where, you know, wherever there's a solution, there is a short witness that can be easily,
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like a polynomial size witness that can be checked in polynomial time, that we call an NP problem,
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okay? And yeah, so every problem that's in P is also in NP, right? Because, you know, you could
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always just ignore the witness and just, you know, if a problem is in P, you can just solve it
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yourself, okay? But now, in some sense, the central, you know, mystery of theoretical computer science
link |
is every NP problem in P. So if you can easily check the answer to a computational problem,
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does that mean that you can also easily find the answer?
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Even though there's all these problems that appear to be very difficult to find the answer,
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it's still an open question whether a good answer exists.
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Because no one has proven that there's no way to do it.
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It's arguably the most, I don't know, the most famous, the most maybe interesting,
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maybe you disagree with that, problem in theoretical computer science. So what's your
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The most famous, for sure.
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P equals NP. If you were to bet all your money, where do you put your money?
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That's an easy one. P is not equal to NP. I like to say that if we were physicists,
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we would have just declared that to be a law of nature, you know, just like thermodynamics.
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Given ourselves Nobel Prizes for its discovery. Yeah, you know, and look, if later it turned out
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that we were wrong, we just give ourselves more Nobel Prizes.
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So harsh, but so true.
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I mean, no, I mean, I mean, it's really just because we are mathematicians or descended
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from mathematicians, you know, we have to call things conjectures that other people
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would just call empirical facts or discoveries, right?
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But one shouldn't read more into that difference in language, you know,
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about the underlying truth.
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So, okay, so you're a good investor and good spender of money. So then let me ask another
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way. Is it possible at all? And what would that look like if P indeed equals NP?
link |
Well, I do think that it's possible. I mean, in fact, you know, when people really pressed
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me on my blog for what odds would I put, I put, you know, two or three percent odds.
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Wow, that's pretty good.
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That P equals NP. Yeah. Well, because, you know, when P, I mean, you really have to think
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about, like, if there were 50, you know, mysteries like P versus NP, and if I made a guess about
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every single one of them, would I expect to be right 50 times? Right? And the truthful
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answer is no. Okay.
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So, you know, and that's what you really mean in saying that, you know, you have, you know,
link |
better than 98% odds for something. Okay. But so, yeah, you know, I mean, there could
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certainly be surprises. And look, if P equals NP, well, then there would be the further
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question of, you know, is the algorithm actually efficient in practice? Right? I mean, Don
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Knuth, who I know that you've interviewed as well, right, he likes to conjecture that
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P equals NP, but that the algorithm is so inefficient that it doesn't matter anyway.
link |
No, I don't know. I've listened to him say that. I don't know whether he says that just
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because he has an actual reason for thinking it's true or just because it sounds cool.
link |
Okay. But, you know, that's a logical possibility, right, that the algorithm could be n to the
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10,000 time, or it could even just be n squared time, but with a leading constant of, it could
link |
be a Google times n squared or something like that. And in that case, the fact that P equals
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NP, well, it would ravage the whole theory of complexity. We would have to rebuild from
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the ground up. But in practical terms, it might mean very little, right, if the algorithm
link |
was too inefficient to run. If the algorithm could actually be run in practice, like if
link |
it had small enough constants, or if you could improve it to where it had small enough constants
link |
that was efficient in practice, then that would change the world. Okay?
link |
You think it would have, like, what kind of impact would it have?
link |
Well, okay, I mean, here's an example. I mean, you could, well, okay, just for starters,
link |
you could break basically all of the encryption that people use to protect the internet.
link |
That's just for starters.
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You could break Bitcoin and every other cryptocurrency, or, you know,
link |
mine as much Bitcoin as you wanted, right? You know, become a super duper billionaire,
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right? And then plot your next move.
link |
Right. That's just for starters. That's a good point.
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Now, your next move might be something like, you know, you now have, like, a theoretically
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optimal way to train any neural network, to find parameters for any neural network, right?
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So you could now say, like, is there any small neural network that generates the entire content
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of Wikipedia, right? If, you know, and now the question is not, can you find it? The
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question has been reduced to, does that exist or not? If it does exist, then the answer would be,
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yes, you can find it, okay? If you had this algorithm in your hands, okay?
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You could ask your computer, you know, I mean, P versus NP is one of these seven problems that
link |
carries this million dollar prize from the Clay Foundation. You know, if you solve it,
link |
you know, and others are the Riemann hypothesis, the Poincare conjecture, which was solved,
link |
although the solver turned down the prize, right, and four others. But what I like to say,
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the way that we can see that P versus NP is the biggest of all of these questions
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is that if you had this fast algorithm, then you could solve all seven of them,
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okay? You just ask your computer, you know, is there a short proof of the Riemann hypothesis,
link |
right? You know, that a machine could, in a language where a machine could verify it,
link |
and provided that such a proof exists, then your computer finds it
link |
in a short amount of time without having to do a brute force search, okay? So, I mean,
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those are the stakes of what we're talking about. But I hope that also helps to give your listeners
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some intuition of why I and most of my colleagues would put our money on P not equaling NP.
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Is it possible, I apologize this is a really dumb question, but is it possible to,
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that a proof will come out that P equals NP, but an algorithm that makes P equals NP
link |
is impossible to find? Is that like crazy? Okay, well, if P equals NP, it would mean
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that there is such an algorithm. That it exists, yeah.
link |
But, you know, it would mean that it exists. Now, you know, in practice, normally the way that we
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would prove anything like that would be by finding the algorithm. But there is such a thing as a
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nonconstructive proof that an algorithm exists. You know, this has really only reared its head,
link |
I think, a few times in the history of our field, right? But, you know, it is theoretically possible
link |
that such a thing could happen. But, you know, there are, even here, there are some amusing
link |
observations that one could make. So there is this famous observation of Leonid Levin, who was,
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you know, one of the original discoverers of NP completeness, right? And he said,
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we'll consider the following algorithm that I guarantee will solve the NP problems efficiently,
link |
just as provided that P equals NP, okay? Here is what it does. It just runs, you know,
link |
it enumerates every possible algorithm in a gigantic infinite list, right? From like in
link |
like alphabetical order, right? You know, and many of them maybe won't even compile,
link |
so we just ignore those, okay? But now, we just, you know, run the first algorithm,
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then we run the second algorithm, we run the first one a little bit more,
link |
then we run the first three algorithms for a while, we run the first four for a while.
link |
This is called dovetailing, by the way. This is a known trick in theoretical computer science,
link |
okay? But we do it in such a way that, you know, whatever is the algorithm out there in our list
link |
that solves NP complete, you know, the NP problems efficiently, will eventually hit that one,
link |
right? And now, the key is that whenever we hit that one, you know, by assumption,
link |
it has to solve the problem, it has to find the solution, and once it claims to find a solution,
link |
then we can check that ourselves, right? Because these are NP problems, then we can check it.
link |
Now, this is utterly impractical, right? You know, you'd have to do this enormous exhaustive search
link |
among all the algorithms, but from a certain theoretical standpoint, that is merely a constant
link |
prefactor, right? That's merely a multiplier of your running time. So, there are tricks like that
link |
one can do to say that, in some sense, the algorithm would have to be constructive. But,
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you know, in the human sense, you know, it is possible that to, you know, it's conceivable
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that one could prove such a thing via a nonconstructive method. Is that likely? I don't
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think so. Not personally. So, that's P and NP, but the complexity zoo is full of wonderful
link |
creatures. Well, it's got about 500 of them. 500. So, how do you get, yeah, how do you get more?
link |
I mean, just for starters, there is everything that we could do with a conventional computer
link |
with a polynomial amount of memory, okay, but possibly an exponential amount of time,
link |
because we get to reuse the same memory over and over again. Okay, that is called P space,
link |
okay? And that's actually, we think, an even larger class than NP. Okay, well, P is contained
link |
in NP, which is contained in P space. And we think that those containments are strict.
link |
And the constraint there is on the memory. The memory has to grow
link |
polynomially with the size of the process. That's right. That's right. But in P space,
link |
we now have interesting things that were not in NP, like as a famous example, you know,
link |
from a given position in chess, you know, does white or black have the win? Let's say,
link |
assuming provided that the game lasts only for a reasonable number of moves, okay? Or likewise,
link |
for go, okay? And, you know, even for the generalizations of these games to arbitrary
link |
size boards, because with an eight by eight board, you could say that's just a constant
link |
size problem. You just, you know, in principle, you just solve it in O of one time, right?
link |
But so we really mean the generalizations of, you know, games to arbitrary size boards here.
link |
Or another thing in P space would be, like, I give you some really hard constraint satisfaction
link |
problem, like, you know, a traveling salesperson or, you know, packing boxes into the trunk of
link |
your car or something like that. And I ask, not just is there a solution, which would be an NP
link |
problem, but I ask how many solutions are there, okay? That, you know, count the number of valid
link |
solutions. That actually gives, those problems lie in a complexity class called sharp P, or like,
link |
it looks like hashtag, like hashtag P, okay, which sits between NP and P space.
link |
There's all the problems that you can do in exponential time, okay? That's called exp. So,
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and by the way, it was proven in the 60s that exp is larger than P, okay? So we know that much.
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We know that there are problems that are solvable in exponential time that are not solvable in
link |
polynomial time, okay? In fact, we even know, we know that there are problems that are solvable in
link |
n cubed time that are not solvable in n squared time. And that, those don't help us with a
link |
controversy between P and NP at all. Unfortunately, it seems not, or certainly not yet, right?
link |
The techniques that we use to establish those things, they're very, very related to how Turing
link |
proved the unsolvability of the halting problem, but they seem to break down when we're comparing
link |
two different resources, like time versus space, or like, you know, P versus NP, okay? But, you know,
link |
I mean, there's what you can do with a randomized algorithm, right? That can be done with a
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random algorithm, right? That can sometimes, you know, has some probability of making a mistake.
link |
That's called BPP, bounded error probabilistic polynomial time. And then, of course, there's
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one that's very close to my own heart, what you can efficiently do in polynomial time using a
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quantum computer, okay? And that's called BQP, right? And so, you know, what's understood about
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it? Okay, so P is contained in BPP, which is contained in BQP, which is contained in P space,
link |
okay? So anything you can, in fact, in something very similar to sharp P. BQP is basically,
link |
you know, well, it's contained in like P with the magic power to solve sharp P problems, okay?
link |
Why is BQP contained in P space?
link |
Oh, that's an excellent question. So there is, well, I mean, one has to prove that, okay? But
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the proof, you could think of it as using Richard Feynman's picture of quantum mechanics,
link |
which is that you can always, you know, we haven't really talked about quantum mechanics in this
link |
conversation. We did in our previous one.
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Yeah, we did last time.
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But yeah, we did last time, okay? But basically, you could always think of a quantum computation
link |
as like a branching tree of possibilities where each possible path that you could take
link |
through, you know, the space has a complex number attached to it called an amplitude, okay? And now
link |
the rule is, you know, when you make a measurement at the end, well, you see a random answer,
link |
okay? But quantum mechanics is all about calculating the probability that you're
link |
going to see one potential answer versus another one, right? And the rule for calculating the
link |
probability that you'll see some answer is that you have to add up the amplitudes for all of the
link |
paths that could have led to that answer. And then, you know, that's a complex number, so that,
link |
you know, how could that be a probability? Then you take the squared absolute value of the result.
link |
That gives you a number between zero and one, okay? So yeah, I just summarized quantum mechanics
link |
in like 30 seconds, okay? But now, you know, what this already tells us is that anything I can do
link |
with a quantum computer, I could simulate with a classical computer if I only have exponentially
link |
more time, okay? And why is that? Because if I have exponential time, I could just write down this
link |
entire branching tree and just explicitly calculate each of these amplitudes, right? You know, that
link |
will be very inefficient, but it will work, right? It's enough to show that quantum computers could
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not solve the halting problem or, you know, they could never do anything that is literally
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uncomputable in Turing's sense, okay? But now, as I said, there's even a stronger result which says
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that BQP is contained in PSPACE. The way that we prove that is that we say, if all I want is to
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calculate the probability of some particular output happening, you know, which is all I need to
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simulate a quantum computer, really, then I don't need to write down the entire quantum state,
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which is an exponentially large object. All I need to do is just calculate what is the amplitude for
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that final state. And to do that, I just have to sum up all the amplitudes that lead to that state.
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Okay, so that's an exponentially large sum, but I can calculate it just reusing the same memory over
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and over for each term in the sum. And hence the p, in the PSPACE? Hence the PSPACE. Yeah.
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So what, out of that whole complexity zoo, and it could be BQP, what do you find is the most,
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the class that captured your heart the most, the most beautiful class that's just, yeah.
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I used, as my email address, bqpqpoly at gmail.com. Yes, because BQP slash Qpoly,
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well, you know, amazingly no one had taken it.
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But, you know, this is a class that I was involved in sort of defining,
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proving the first theorems about in 2003 or so. So it was kind of close to my heart.
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But this is like, if we extended BQP, which is the class of everything we can do efficiently
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with a quantum computer, to allow quantum advice, which means imagine that you had some
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special initial state, okay, that could somehow help you do computation. And maybe
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such a state would be exponentially hard to prepare, okay, but maybe somehow these states
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were formed in the Big Bang or something, and they've just been sitting around ever since,
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right? If you found one, and if this state could be like ultra power, there are no limits on how
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powerful it could be, except that this state doesn't know in advance which input you've got,
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right? It only knows the size of your input. You know, and that's BQP slash Qpoly. So that's
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one that I just personally happen to love, okay? But, you know, if you're asking like what's the,
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you know, there's a class that I think is way more beautiful or fundamental than a lot of people
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even within this field realize that it is. That class is called SZK, or Statistical Zero Knowledge.
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And, you know, there's a very, very easy way to define this class, which is to say, suppose that
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I have two algorithms that each sample from probability distributions, right? So each one
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just outputs random samples according to, you know, possibly different distributions. And now
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the question I ask is, you know, let's say distributions over strings of n bits, you know,
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so over an exponentially large space. Now I ask, are these two distributions close or far as
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close or far as probability distributions? Okay. Any problem that can be reduced to that,
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you know, that can be put into that form is an SZK problem. And the way that this class was
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originally discovered was completely different from that and was kind of more complicated. It
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was discovered as the class of all of the problems that have a certain kind of what's called zero
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knowledge proof. Zero knowledge proofs are one of the central ideas in cryptography. You know,
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Shafi Goldwasser and Silvio McCauley won the Turing Award for, you know, inventing them.
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And they're at the core of even some cryptocurrencies that, you know, people use
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nowadays. But zero knowledge proofs are ways of proving to someone that something is true,
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like, you know, that there is a solution to this, you know, optimization problem or that these two
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graphs are isomorphic to each other or something, but without revealing why it's true, without
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revealing anything about why it's true. Okay. SZK is all of the problems for which there is such a
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proof that doesn't rely on any cryptography. Okay. And if you wonder, like, how could such a thing
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possibly exist, right? Well, like, imagine that I had two graphs and I wanted to convince you
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that these two graphs are not isomorphic, meaning, you know, I cannot permute one of them so that
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it's the same as the other one, right? You know, that might be a very hard statement to prove,
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right? I might need, you know, you might have to do a very exhaustive enumeration of, you know,
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all the different permutations before you were convinced that it was true. But what if there were
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some all knowing wizard that said to you, look, I'll tell you what, just pick one of the graphs
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randomly, then randomly permute it, then send it to me and I will tell you which graph you started
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with. Okay. And I will do that every single time. Right. And let's say that that wizard did that a
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hundred times and it was right every time. Yeah. Right. Now, if the graphs were isomorphic, then,
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you know, it would have been flipping a coin each time, right? It would have had only a one and two
link |
to the 100 power chance of, you know, of guessing right each time. But, you know, so, so if it's
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right every time, then now you're statistically convinced that these graphs are not isomorphic,
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even though you've learned nothing new about why they aren't. So fascinating. So yeah. So,
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so SDK is all of the problems that have protocols like that one, but it has this beautiful other
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characterization. It's shown up again and again in my, in my own work and, you know, a lot of
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people's work. And I think that it really is one of the most fundamental classes. It's just that
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people didn't realize that when it was first discovered. So we're living in the middle of
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a pandemic currently. Yeah. How has your life been changed or no better to ask, like, how has your
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perspective of the world change with this world changing event of a pandemic overtaking the entire
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world? Yeah. Well, I mean, I mean, all of our lives have changed, you know, like, I guess,
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as with no other event since I was born, you know, you would have to go back to world war II
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for something, I think of this magnitude, you know, on, you know, the way that we live our lives
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as for how it has changed my worldview. I think that the, the failure of institutions,
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you know, like, like, like the CDC, like, you know, other institutions that we sort of thought
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were, were trustworthy, like a lot of the media was staggering, was, was absolutely breathtaking.
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It is something that I would not have predicted. Right. I think I, I wrote on my blog that, you
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know, the, you know, it's, it's, it's fascinating to like rewatch the movie Contagion from a decade
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ago, right. That correctly foresaw so many aspects of, you know, what was going on, you know, an
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airborne, you know, virus originates in China, spreads to, you know, much of the world, you know,
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shuts everything down until a vaccine can be developed. You know, everyone has to stay at home,
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you know, you know, it gets, you know, an enormous number of things, right. Okay. But the one thing
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that they could not imagine, you know, is that like in this movie, everyone from the government
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is like hyper competent, hyper, you know, dedicated to the public good, right. And you
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know, yeah, they're the, they're the best of the best, you know, they could, you know, and, and
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there are these conspiracy theorists, right. Who think, you know, you know, this is all fake news.
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There's no, there's not really a pandemic. And those are some random people on the internet who
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the hyper competent government people have to, you know, oppose, right. They, you know, in, in trying
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to envision the worst thing that could happen, like, you know, the, the, there was a failure of
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imagination. The movie makers did not imagine that the conspiracy theorists and the, you know,
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and the incompetence and the nutcases would have captured our institutions and be the ones actually
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running things. So you had a certain, I love competence in all walks of life. I love, I get
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so much energy. I'm so excited by people who do amazing job. And I like you, or maybe you can
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clarify, but I had maybe not intuition, but I hope that government at its best could be ultra
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competent. What, first of all, two questions, like how do you explain the lack of confidence
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and the other, maybe on the positive side, how can we build a more competent government?
link |
Well, there's an election in two months. I mean, you have a faith that the election,
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I, you know, it's not going to fix everything, but you know, it's like,
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I feel like there is a ship that is sinking and you could at least stop the sinking.
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But, you know, I think that there are much, much deeper problems. I mean, I think that,
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you know, it is plausible to me that, you know, a lot of the failures, you know, with the CDC,
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with some of the other health agencies, even, you know, predate Trump, you know, predate the,
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you know, right wing populism that has sort of taken over much of the world now. And, you know,
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I think that, you know, it is, you know, it is very, I'm actually, you know, I've actually been
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strongly in favor of, you know, rushing vaccines of, you know, I thought that we could have done,
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you know, human challenge trials, you know, which were not done, right? We could have, you know,
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like had, you know, volunteers, you know, to actually, you know, be, you know, get vaccines,
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get, you know, exposed to COVID. So innovative ways of accelerating what we've done previously
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over a long time. I thought that, you know, each month that a vaccine is closer is like trillions
link |
of dollars. Are you surprised? And of course, lives, you know, at least, you know, hundreds
link |
of thousands of lives. Are you surprised that it's taking this long? We still don't have a plan.
link |
There's still not a feeling like anyone is actually doing anything in terms of alleviating,
link |
like any kind of plan. So there's a bunch of stuff, there's vaccine, but you could also do
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a testing infrastructure where everybody's tested nonstop with contact tracing, all that kind of.
link |
Well, I mean, I'm as surprised as almost everyone else. I mean, this is a historic failure. It is
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one of the biggest failures in the 240 year history of the United States, right? And we should
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be, you know, crystal clear about that. And, you know, one thing that I think has been missing,
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you know, even from the more competent side is like, you know, is sort of the World War II
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mentality, right? The, you know, the mentality of, you know, let's just, you know, you know,
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if we can, by breaking a whole bunch of rules, you know, get a vaccine and, you know, and even
link |
half the amount of time as we thought, then let's just do that because, you know, like we have to
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weigh all of the moral qualms that we have about doing that against the moral qualms of not doing.
link |
And one key little aspect to that that's deeply important to me, and we'll go into that topic
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next, is the World War II mentality wasn't just about, you know, breaking all the rules to get
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the job done. There was a togetherness to it. So I would, if I were president right now, it seems
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quite elementary to unite the country because we're facing a crisis. It's easy to make the
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virus the enemy. And it's very surprising to me that the division has increased as opposed to
link |
decrease. That's heartbreaking. Yeah. Well, look, I mean, it's been said by others that this is the
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first time in the country's history that we have a president who does not even pretend to, you know,
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want to unite the country. I mean, Lincoln, who fought a civil war, said he wanted to unite the
link |
country. And I do worry enormously about what happens if the results of this election are
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contested. And will there be violence as a result of that? And will we have a clear path of succession?
link |
And, you know, look, I mean, you know, this is all we're going to find out the answers to this in
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two months. And if none of that happens, maybe I'll look foolish. But I am willing to go on the
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record and say, I am terrified about that. Yeah, I've been reading The Rise and Fall of the Third
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Reich. So if I can, this is like one little voice just to put out there that I think November will
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be a really critical month for people to breathe and put love out there. Do not, you know, anger in
link |
those in that context, no matter who wins, no matter what is said, will destroy our country,
link |
may destroy our country, may destroy the world because of the power of the country. So it's
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really important to be patient, loving, empathetic. Like one of the things that troubles me is that
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even people on the left are unable to have a love and respect for people who voted for Trump. They
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can't imagine that there's good people that could vote for the opposite side. Oh, I know there are
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because I know some of them, right? I mean, you know, it's still, you know, maybe it baffles me,
link |
but, you know, I know such people. Let me ask you this. It's also heartbreaking to me
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on the topic of cancel culture. So in the machine learning community, I've seen it a little bit
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that there's aggressive attacking of people who are trying to have a nuanced conversation about
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things. And it's troubling because it feels like nuanced conversation is the only way to talk about
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difficult topics. And when there's a thought police and speech police on any nuanced conversation
link |
that everybody has to like in a animal farm chant that racism is bad and sexism is bad, which is
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things that everybody believes and they can't possibly say anything nuanced. It feels like it
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goes against any kind of progress from my kind of shallow perspective. But you've written a little
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bit about cancel culture. Do you have thoughts there? Well, I mean, to say that I am opposed to,
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you know, this trend of cancellations or of shouting people down rather than engaging them,
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that would be a massive understatement, right? And I feel like, you know, I have put my money
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where my mouth is, you know, not as much as some people have, but, you know, I've tried to do
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something. I mean, I have defended, you know, some unpopular people and unpopular, you know, ideas
link |
on my blog. I've, you know, tried to defend, you know, norms of open discourse, of, you know,
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reasoning with our opponents, even when I've been shouted down for that on social media,
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you know, called a racist, called a sexist, all of those things. And which, by the way,
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I should say, you know, I would be perfectly happy to, you know, if we had time to say, you know,
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you know, 10,000 times, you know, my hatred of racism, of sexism, of homophobia, right?
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But what I don't want to do is to cede to some particular political faction the right to define
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exactly what is meant by those terms to say, well, then you have to agree with all of these other
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extremely contentious positions or else you are a misogynist or else you are a racist, right?
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I say that, well, no, you know, don't I or, you know, don't people like me also get a say in the
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discussion about, you know, what is racism, about what is going to be the most effective to combat
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racism, right? And, you know, this cancellation mentality, I think, is spectacularly ineffective
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at its own professed gall of, you know, combating racism and sexism.
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What's a positive way out? So I, I try to, I don't know if you see what I do on Twitter,
link |
but I, on Twitter, I mostly, in my whole, in my life, I've actually, it's who I am to the core is
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like, I really focus on the positive and I try to put love out there in the world. And still,
link |
I get attacked. And I look at that and I wonder like,
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You too? I didn't know.
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Like, I haven't actually said anything difficult and nuanced. You talk about somebody like
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Steven Pinker, who I'm actually don't know the full range of things that he's attacked for,
link |
but he tries to say difficult. He tries to be thoughtful about difficult topics.
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And obviously he just gets slaughtered by.
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Well, I mean, yes, but it's also amazing how well Steve has withstood it. I mean,
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he just survived that attempt to cancel him just a couple of months ago, right?
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Psychologically, he survives it too, which worries me because I don't think I can.
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Yeah, I've gotten to know Steve a bit. He is incredibly unperturbed by this stuff.
link |
And I admire that and I envy it. I wish that I could be like that. I mean, my impulse when I'm
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getting attacked is I just want to engage every single like anonymous person on Twitter and Reddit
link |
who is saying mean stuff about me. And I want to just say, well, look, can we just talk this over
link |
for an hour? And then you'll see that I'm not that bad. And sometimes that even works. The
link |
problem is then there's the 20,000 other ones.
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That's not, but psychologically, does that wear on you?
link |
It does. It does. But yeah, I mean, in terms of what is the solution, I mean, I wish I knew,
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right? And so in a certain way, these problems are maybe harder than P versus NP, right?
link |
I mean, but I think that part of it has to be that I think that there's a lot of sort of silent
link |
support for what I'll call the open discourse side, the reasonable enlightenment side.
link |
And I think that that support has to become less silent, right? I think that a lot of people
link |
just sort of agree that a lot of these cancellations and attacks are ridiculous,
link |
but are just afraid to say so, right? Or else they'll get shouted down as well, right? That's
link |
just the standard witch hunt dynamic, which, of course, this faction understands and exploits to
link |
its great advantage. But more people just said, we're not going to stand for this, right? This
link |
is, guess what? We're against racism too. But what you're doing is ridiculous, right? And the
link |
hard part is it takes a lot of mental energy. It takes a lot of time. Even if you feel like
link |
you're not going to be canceled or you're staying on the safe side, it takes a lot of time to
link |
phrase things in exactly the right way and to respond to everything people say.
link |
So, but I think that the more people speak up from all political persuasions, from all walks
link |
of life, then the easier it is to move forward. Since we've been talking about love, can you,
link |
last time I talked to you about meaning of life a little bit, but here has, it's a weird question
link |
to ask a computer scientist, but has love for other human beings, for things, for the world
link |
around you played an important role in your life? Have you, it's easy for a world class
link |
computer scientist, you could even call yourself like a physicist, everything to be lost in the
link |
books. Is the connection to other humans, love for other humans played an important role?
link |
I love my kids. I love my wife. I love my parents. I'm probably not different from most people in
link |
loving their families and in that being very important in my life. Now, I should remind you
link |
that I am a theoretical computer scientist. If you're looking for deep insight about the nature
link |
of love, you're probably looking in the wrong place to ask me, but sure, it's been important.
link |
But is there something from a computer science perspective to be said about love? Is that even
link |
beyond into the realm of consciousness? There was this great cartoon, I think it
link |
was one of the classic XKCDs where it shows a heart and it's squaring the heart, taking the
link |
four year transform of the heart, integrating the heart, each thing and then it says my normal
link |
approach is useless here. I'm so glad I asked this question. I think there's no better way to
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end this. I hope we get a chance to talk again. This has been an amazing, cool experiment to do
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it outside. I'm really glad you made it out. Yeah. Well, I appreciate it a lot. It's been a
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pleasure and I'm glad you were able to come out to Austin. Thanks. Thanks for listening to this
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conversation with Scott Aaronson. And thank you to our sponsors, 8sleep, SimpliSafe, ExpressVPN,
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and BetterHelp. Please check out these sponsors in the description to get a discount and to
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support this podcast. If you enjoy this thing, subscribe on YouTube, review it with five stars
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on Apple Podcast, follow on Spotify, support on Patreon, or connect with me on Twitter
link |
at Lex Friedman. And now let me leave you with some words from Scott Aaronson that I also gave
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to you in the introduction, which is, if you always win, then you're probably doing something
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wrong. Thank you for listening and for putting up with the intro and outro in this strange room in
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the middle of nowhere. And I very much hope to see you next time in many more ways than one.