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EPISODE LINKS:
Scott's Blog: https://www.scottaaronson.com/blog/
Our previous episode: https://www.youtube.com/watch?v=uX5t8EivCaM

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OUTLINE:
0:00 - Introduction
3:31 - Simulation
8:22 - Theories of everything
14:02 - Consciousness
36:16 - Roger Penrose on consciousness
46:28 - Turing test
50:16 - GPT-3
58:46 - Universality of computation
1:05:17 - Complexity
1:11:23 - P vs NP
1:23:41 - Complexity of quantum computation
1:35:48 - Pandemic
1:49:33 - Love

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The following is a conversation with Scott Aronson, his second time on the podcast.

He is a professor at UT Austin, director of the Quantum Information Center, and previously a professor at MIT.

Last time we talked about quantum computing, this time we talk about computation complexity, consciousness and theories of everything.

I'm recording this intro, as you may be able to tell, in a very strange room in the middle of the night.

I'm not really sure how I got here or how I'm going to get out, but Hunter S.

Thompson saying I think applies to today and the last few days and actually the last couple of weeks.

Life should not be a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming, wow, what a ride.

So I figured, whatever I'm up to here, and yes, lots of wine is involved, I'm going to have to improvise, hence this recording.

Okay, quick mention of each sponsor, followed by some thoughts related to the episode.

First sponsor is SimpliSafe, a home security company I use to monitor and protect my apartment.

Though Of course, I'm always prepared with a fallback plan, as a man in this world must always be.

A mattress that cools itself, measures heart rate variability, has a nap, and has given me yet another reason to look forward to sleep, including the all-important PowerNap.

The third sponsor is ExpressVPN, the VPN I've used for many years to protect my privacy on the internet.

Finally, the fourth sponsor is BetterHelp.

Online therapy when you want to face your demons with a licensed professional, not just by doing David Goggins-like physical challenges like I seem to do on occasion.

Please check out the sponsors in the description to get a discount and to support the podcast.

As a side note, let me say that this is the second time I recorded a conversation outdoors.

The first 1 was with Stephen Wolfram when it was actually sunny out.

In this case, it was raining, which is why I found a covered outdoor patio.

But I learned a valuable lesson, which is that raindrops can be quite loud on the hard metal surface of a patio cover.

In fact, as Scott says, if you always win, then you're probably doing something wrong.

To be honest, I get pretty upset with myself when I fail, small or big, but I've learned that this feeling is priceless.

It can be fuel when channeled into concrete plans of how to improve.

So If you enjoy this thing, subscribe on YouTube, review the 5 Stars on Apple Podcast, follow on Spotify, support on Patreon, or connect with me on Twitter at Lex Friedman.

And now, here's my conversation with Scott Aronson.

Let's start with the most absurd question,

but I've read you write some fascinating stuff about it, so let's go there.

Because if we are living in a simulation, it raises the question, how real does something have to be in simulation for it to be sufficiently immersive for us humans?

But I mean, even in principle, how could we ever know if we were in 1, right?

A perfect simulation, by definition, is something that's indistinguishable from the real thing.

But we didn't say anything about perfect.

Well, if it was an imperfect simulation, if we could hack it, you know, find a bug in it, then that would be 1 thing, right?

If this was like the Matrix, and there was a way for me to do flying Kung Fu moves or something by hacking the simulation, well then we would have to cross that bridge when we came to it, wouldn't we?

I mean at that point, it's hard to see the difference between that and just what people would ordinarily refer to as a world with miracles.

What about from a different perspective, thinking about the universe as a computation, like a program running on a computer?

It is an interesting and reasonably well-defined question to ask, is the world computable?

Does the world satisfy what we would call in CS the the church touring thesis?

That is, could we take any physical system and simulate it to any desired precision by a Turing machine, given the appropriate input data?

And so far, I think the indications are pretty strong that our world does seem to satisfy the Church-Turing thesis.

At least if it doesn't, then we haven't yet discovered why not.

But now, does that mean that our universe is a simulation?

Well, you know, that word seems to suggest that there is some other larger universe in which it is running, right?

And the problem there is that if the simulation is perfect, then we're never going to be able to get any direct evidence about that other universe.

You know, we will only be able to see the effects of the computation that is running in this universe.

Let's imagine a PC, a personal computer, a computer.

Is it possible with the advent of artificial intelligence for the computer to look outside of itself to understand its creator.

Well, I mean, with the computers that we actually have, I mean, first of all, we all know that humans have done an imperfect job of enforcing the abstraction boundaries of computers, right?

You may try to confine some program to a playpen, But as soon as there's 1 memory allocation error in the C program, then the program has gotten out of that playpen and it can do whatever it wants.

This is how most hacks work, the viruses and worms and exploits.

And you would have to imagine that an AI would be able to discover something like that.

Now, of course, if we could actually discover some exploit of reality itself, then in some sense we wouldn't have to philosophize about this.

This would no longer be a metaphysical conversation.

But the question is, what would that hack look like?

I mean, Peter Shore, the very famous person in quantum computing, of course, has joked that maybe the reason why we haven't yet integrated general relativity in quantum mechanics is that the part of the universe that depends on both of them was actually left unspecified.

And if we ever tried to do an experiment involving the singularity of a black hole or something like that, then the universe would just generate an overflow error or something, right?

Now, the universe has seemed to hold up pretty well for 14 billion years, right?

So, my Occam's razor kind of guess has to be that it will continue to hold up.

The fact that we don't know the laws of physics governing some phenomenon is not a strong sign that probing that phenomenon is going to crash the universe, right?

But you know, of course I could be wrong.

But do you think on the physics side of things, you know, there's been recently a few folks, Eric Weinstein and Stephen Wolfram that came out with the Theory of Everything.

I think there's a history of physicists dreaming and working on the unification of all the laws of physics.

Do you think it's possible that once we understand more physics, not necessarily the unification of the laws, but just understand physics more deeply at the fundamental level, we'll be able to start, you know, I mean part of this is humorous, but looking to see if there's any bugs in the universe that could be exploited for traveling at not just speed of light, but just traveling faster than our current spaceships can travel, all that kind of stuff.

Well, I mean, to travel faster than our current spaceships could travel, you wouldn't need to find any bug in the universe, right?

The known laws of physics, you know, let us go much faster up to the speed of light, right?

And you know, when people want to go faster than the speed of light, well, we actually know something about what that would entail, namely that, you know, according to relativity, that seems to entail communication backwards in time.

So then you have to worry about closed time-like curves and all of that stuff.

So in some sense, we sort of know the price that you have to pay for these things.

We can't say that they're impossible, but we know that sort of a lot else in physics breaks, right?

So now regarding Eric Weinstein and Stephen Wolfram, I wouldn't say that either of them has a theory of everything.

I would say that they have ideas that they hope could someday lead to a theory of everything.

Well, I mean, certainly, let's say by theory of everything, we don't literally mean a theory of cats and of baseball, but we just mean it in the more limited sense of everything, a fundamental theory of physics, of all of the fundamental interactions of physics.

Of course, such a theory, even after we had it, would leave the entire question of all the emergent behavior to be explored.

So it's only everything for a specific definition of everything.

Okay, but in that sense, I would say, of course that's worth pursuing.

I mean, that is the entire program of fundamental physics, right?

All of my friends who do quantum gravity, who do string theory, who do anything like that, that is what's motivating them.

Yeah, it's funny though, but I mean, Eric Weinstein talks about this.

It is, I don't know much about the physics world, but I know about the AI world.

And it is a little bit taboo to talk about AGI, for example, on the AI side.

So really to talk about the big dream of the community, I would say, because it seems so far away, it's almost taboo to bring it up because It's seen as the kind of people that dream about creating a truly superhuman level of intelligence that's really far out there.

People because we're not even close to that.

And it feels like the same thing is true for the physics community.

I mean, Stephen Hawking certainly talked constantly about theory of everything.

I mean, people use those terms who were some of the most respected people in the whole world of physics.

But I think that The distinction that I would make is that people might react badly if you use the term in a way that suggests that you, you know, thinking about it for 5 minutes, have come up with this major new insight about it.

Stephen Hawking is not a great example because I think you can do whatever the heck you want when you get to that level.

And I certainly see senior faculty, at that point, That's 1 of the nice things about getting older is you stop giving a damn.

But the community as a whole, they tend to roll their eyes very quickly at stuff that's outside the quote-unquote mainstream.

If you asked Ed Witten, let's say, who you might consider a leader of the string community and thus, you know, very, very mainstream in a certain sense, but he would have no hesitation in saying, you know, of course, you know, they're looking for a, you know, a unified description of nature, of, you know, of general relativity, of quantum mechanics, of all the fundamental interactions of nature, right?

Now, whether people would call that a theory of everything, whether they would use that term, that might vary.

You know, Lenny Suskin would definitely have no problem telling you that, you know, if that's what we want, right?

For me, who loves human beings and psychology, it's kind of ridiculous to say a theory that unifies the laws of physics gets you to understand everything.

I would say you're not even close to understanding everything.

Yeah, right, well, yeah, I mean, the word everything is a little ambiguous here, right?

Because, you know, and then people will get into debates about, you know, reductionism versus emergentism and blah, blah, blah.

And so in not wanting to say theory of everything, people might just be trying to short circuit that debate and say, look, yes, we want a fundamental theory of the particles and interactions of nature.

Let me bring up the next topic that people don't want to mention, although they're getting more comfortable with it, is consciousness.

You mentioned that you have a talk on consciousness that I watched 5 minutes of, but the internet connection was really bad.

Was this my talk about refuting the integrated information theory?

this particular account of consciousness that I think 1 can just show it doesn't work.

Let me ask, maybe it'd be nice to comment on, you talk about also the semi-hard problem of consciousness, or like almost hard, or kind

So maybe can you talk about that, their idea of the approach to modeling consciousness and why you don't find it convincing?

Okay, well, so what I call the pretty hard problem of consciousness, this is my term, although many other people have said something equivalent to this, okay?

But it's just the problem of giving an account of just which physical systems are conscious and which are not.

Or if there are degrees of consciousness, then quantifying how conscious a given system is.

Oh, awesome, So that's the pretty hard problem.

And so, the infamous hard problem of consciousness is to explain how something like consciousness could arise at all in a material universe, right?

Or why does it ever feel like anything to experience anything, right?

And so I'm trying to distinguish from that problem, right?

And say, you know, no, okay, I would merely settle for an account that could say, is a fetus conscious?

Or even as a precondition, you take that both these things are conscious, tell me which is more conscious.

Yeah, yeah, I mean, if consciousness is some multidimensional vector, well, just tell me in which respects these things are conscious and in which respect they aren't, right?

And have some principled way to do it where you're not carving out exceptions for things that you like or don't like, but could somehow take a description of an arbitrary physical system and then just based on the physical properties of that system or the informational properties or how it's connected or something like that just in principle calculate you know its degree of consciousness right I mean this this this would be the kind of thing that we would need you know if we wanted to address questions like, you know, what does it take for a machine to be conscious, right?

Or when should we regard AIs as being conscious?

So now this IIT, this integrated information theory, which has been put forward by Giulio Tononi and a bunch of his collaborators over the last decade or 2.

This is noteworthy, I guess, as a direct attempt to answer that question, to address the pretty hard problem, right?

And they give a criterion that's just based on how a system is connected.

So it's up to you to sort of abstract a system like a brain or a microchip as a collection of components that are connected to each other by some pattern of connections, and to specify how the components can influence each other, like where the inputs go, where they affect the outputs.

But then once you've specified that, then they give this quantity that they call phi, you know, the Greek letter phi.

And the definition of phi has actually changed over time.

It changes from 1 paper to another, but in all of the variations it involves something about what we in computer science would call graph expansion.

So basically what this means is that they want it in order to get a large value of phi, it should not be possible to take your system and partition it into 2 components that are only weakly connected to each other.

So whenever we take our system and sort of try to split it up into 2, then there should be lots and lots of connections going between the 2 components.

Well, I understand what that means on a graph.

Do they formalize how to construct such a graph or data structure, whatever?

1 of the criticisms I've heard you kind of say is that a lot of the very interesting specifics are usually communicated through natural language, like through words, so it's like the details aren't always clear.

I mean, they have nothing even resembling a derivation of this phi.

So what they do is they state a whole bunch of postulates, axioms that they think that consciousness should satisfy.

And then at some point, Phi appears, right?

And this was the first thing that really made the hair stand on my neck, to be honest, because they are acting as if there's a derivation.

They're acting as if you're supposed to think that this is a derivation, and there's nothing even remotely resembling a derivation.

They just pull the fee out of a hat completely.

Is 1 of the key criticisms to you is that details are missing, or is there something more fundamental?

The core of it is that I think that they want to say that a system is more conscious the larger its value of phi.

As soon as you think about it for a minute, as soon as you think about it in terms of, could I construct a system that had an enormous value of phi, like even larger than the brain has, but that is just implementing and error-correcting code, doing nothing that we would associate with intelligence or consciousness or any of it, the answer is yes, it is easy to do that.

And so I wrote blog posts just making this point that yeah, it's easy to do that.

Now, Tinoni's response to that was actually kind of incredible.

I mean, I admired it in a way, because instead of disputing any of it, he just bit the bullet in the sense, you know, he was 1 of the most audacious bullet bitings I've ever seen in my career, OK?

You know, this system that just applies this error correcting code, it's conscious.

And if it has a much larger value of phi than you or me, it's much more conscious than

We just have to accept what the theory says because science is not about confirming our intuitions, it's about challenging them.

And this is what my theory predicts, that this thing is conscious, and are super duper conscious, and how are you gonna prove me wrong?

So the way I would argue against your blog post is I would say, yes, sure, you're right in general, but for naturally arising systems developed through the process of evolution on Earth, this rule of the larger fee being associated with more consciousness is correct.

Because he wants this to be completely general.

Yeah, I mean the whole interest of the theory is the hope that it could be completely general, apply to aliens, to computers, to animals, coma patients, to any of it, right?

And so he just said, well, you know, Scott is relying on his intuition, but I'm relying on this theory.

And to me, it was almost like, are we being serious here?

Yes, in science, we try to learn highly non-intuitive things, But what we do is we first test the theory on cases where we already know the answer, right?

Like if someone had a new theory of temperature, right?

Then maybe we could check that it says that boiling water is hotter than ice.

And then if it says that the Sun is hotter than anything you've ever experienced, then maybe we trust that extrapolation, right?

But this theory, it's now saying that a gigantic grid, like regular grid of exclusive or gates can be way more conscious than a person or than any animal can be, even if it is so uniform that it might as well just be a blank wall.

And so now the point is, if this theory is sort of getting wrong, the question is a blank wall more conscious than a person, then I would say what is there for it to get right?

So your sense is a blank wall is not more conscious than a human being.

Yeah, I mean, you could say that I am taking that as 1 of my axioms.

I'm saying that if a theory of consciousness is getting that wrong, then whatever it is talking about, at that point I'm not going to call it consciousness.

I mean, it's possible, just like with intelligence, that us humans conveniently define these very difficult to understand concepts in a very human-centric way.

Just like the Turing test really seems to define intelligence as a thing that's human-like.

Right, but I would say that with any concept, there's, we first need to define it, right?

And a definition is only a good definition if it matches what we thought we were talking about prior to having a definition, right?

And I would say that phi, as a definition of consciousness, fails that test.

So you mentioned that the universe might be a Turing machine, so like, it might be computation.

So what's your sense about consciousness?

Do you think consciousness is computation?

That we don't need to go to any place outside of the computable universe to understand consciousness, to build consciousness, to measure consciousness, all those kinds of things?

These are what have been called the vertiginous questions.

They're the questions like you get a feeling of vertigo when thinking about them, right?

I mean, I certainly feel like I am conscious in a way that is not reducible to computation, but why should you believe me, right?

I mean, and if you said the same to me, then why should I believe you?

But as computer scientists, I feel like a computer could achieve human level intelligence.

And that's actually a feeling and a hope.

The same kind of intuition you use in your blog, that's what scientists do.

I mean, some of it is a scientific method, but some of it is just damn good intuition.

I don't have a good intuition about consciousness.

Yeah, I'm not sure that anyone does or has in the 2,500 years that these things have been discussed, Lex.

Like 1 of the, I got a chance to attend, can't wait to hear your opinion on this, but attend the Neuralink event, and 1 of the dreams there is to basically push neuroscience forward.

The hope with neuroscience is that we can inspect the machinery from which all this fun stuff emerges and see, are we going to notice something special, some special sauce from which something like consciousness or cognition emerges?

Yeah, well it's clear that we've learned an enormous amount about neuroscience.

We've learned an enormous amount about computation, you know, about machine learning, about AI, how to get it to work.

We've learned an enormous amount about the underpinnings of the physical world.

From 1 point of view, that's like an enormous distance that we've traveled along the road to understanding consciousness.

From another point of view, the distance still to be traveled on the road maybe seems no shorter than it was at the beginning.

I mean, these are questions like, in sort of trying to have a theory of consciousness, there's sort of a problem where it feels like it's not just that we don't know how to make progress, it's that it's hard to specify what could even count as progress.

Because no matter what scientific theory someone proposed, someone else could come along and say, well, you've just talked about the mechanism.

You haven't said anything about what breathes fire into the mechanism, what really makes there something that it's like to be it.

And that seems like an objection that you could always raise no matter how much someone elucidated the details of how the brain works.

Okay, let's go to Turing test and Lobna Prize.

I have this intuition, call me crazy, but that a machine to pass the Turing test in its full, whatever the spirit of it is, we can talk about how to formulate the perfect Turing test, that that machine has to be conscious.

Or we at least have to, I have a very low bar of what consciousness is.

I tend to think that the emulation of consciousness is as good as consciousness.

So like consciousness is just a dance, a social shortcut, like a nice useful tool.

But I tend to connect intelligence and consciousness together, so by that do you, maybe just to ask, what role does consciousness play, do you think, in passing the Turing test?

Well, look, I mean, it's almost tautologically true that if we had a machine that passed the Turing test, then it would be emulating consciousness, right?

So if your position is that emulation of consciousness is consciousness, then by definition, any machine that passed the Turing test would be conscious.

But I mean, you could say that that is just a way to rephrase the original question, you know, is an emulation of consciousness, you know, necessarily conscious, right?

And you can, you know, I hear, I'm not saying anything new that hasn't been debated ad nauseam in the literature, okay?

But you know, you could imagine some very hard cases, like imagine a machine that passed the Turing test, but it did so just by an enormous, cosmological-sized lookup table that just cached every possible conversation that could be had.

I mean, the Chinese room actually would be doing some computation, at least in Searle's version, right?

Here, I'm just talking about a table lookup, okay?

Now, it's true that for conversations of a reasonable length this lookup table would be so enormous it wouldn't even fit in the observable universe.

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Scott Aaronson: Computational Complexity and Consciousness | Lex Fridman Podcast #130