Lex Fridman Podcast - Pieter Abbeel: Deep Reinforcement Learning

Episode Date: December 17, 2018

Pieter Abbeel is a professor at UC Berkeley, director of the Berkeley Robot Learning Lab, and is one of the top researchers in the world working on how to make robots understand and interact with the world around them, especially through imitation and deep reinforcement learning. Video version is available on YouTube. If you would like to get more information about this podcast go to https://lexfridman.com/ai or connect with @lexfridman on Twitter, LinkedIn, Facebook, or YouTube where you can watch the video versions of these conversations.

The following is a conversation with Peter Abiel. He's a professor at UC Berkeley and the director of the Berkeley Robotics Learning Lab. He's one of the top researchers in the world working on how to make robots understand and interact with the world around them, especially using imitation and deeper enforcement learning. This conversation is part of the MIT course on artificial general intelligence and the artificialificial Intelligence Podcast. If you enjoy it, please subscribe on YouTube, iTunes, or your podcast provider of choice,

or simply connect with me on Twitter at Lex Friedman, spelled F-R-I-D. And now, here's my conversation with Peter Abiel. a bill You've mentioned that if there was one person you could meet you'll be Roger Federer. So let me ask When do you think we'll have a robot that fully autonomously can beat Roger Federer at tennis? At Roger Federer level player at tennis? Huh, well, first, if you can make it happen for me to meet Roger, let me know. I'm just getting a robot to beat him at tennis.

It's kind of an interesting question because for a lot of the challenges we think about in AI, the software is really the missing piece, but for something like this, the hardware is nowhere near either. Like, to really have a robot that can physically run around, the Boston Dynamics robots are starting to get there, but still not really human level ability to run around and then swing a racket. So you think that's a hardware problem? I don't think it's a hardware problem only.

I think it's a hardware and a software problem. I think it's both. And I think they'll have independent progress. So I'd say the hardware may be in 10, 15 years. This play, not grass. I mean, grass probably are. With the sliding. Yeah.

Well, they'll play, I'm not sure what's harder, grass or clay. The clay involves sliding, which might be harder to master actually. Yeah. But you're not limited to bipedal. I'm sure they're going to be. Well, we can build a machine.

It's a whole different question, of course. If you can say, okay, this robot can be on wheels, it can move around on wheels, and can be designed differently, then I think that can be done sooner, probably, than a full humanoid type of setup. What do you think is swing a rack? So you've worked at basic manipulation. How hard do you think is the task of swinging a racket would be able to hit a nice backhand or a forehand?

Let's say we just set up stationary, a nice robot arm, let's say, you know, a standard industrial arm, and it can wash the ball come and and swing the racket. It's a good question. I'm not sure it would be super hard to do. I mean, I'm sure it would require a lot of trial and error. It's not going to swing it right the first time around, but yeah, I don't see why I couldn't.

It's learning it the right way So you think it's learnable? I think it's learnable. I think it's learnable. I think if you set up a ball machine, let's say on one side, and then a robot with a tennis racket on the other side, I think it's learnable and maybe a little bit of pre-training and simulation. Yeah, I think that's feasible.

I think the swing the racket is feasible. I'd be very interesting to see how much precision it can get. Because I mean, that's where some of the human players can hit it on the lines, which is very high precision. With spin. With spin. Is it interesting whether RL can learn to put a spin on the ball? Well, you got me interested.

Maybe some they will set the shot. Sure. You got me interested. Maybe some they will set the sun. Sure. But then your answer is basically, okay, for this problem, it sounds fascinating, but for the general problem of a tennis player, we might be a little bit farther away. What's the most impressive thing you've seen a robot do in the physical world?

So, physically, for me, it's the Boston Dynamics videos, always just bring home and just super impressed. Recently the robot running up the stairs, doing the parkour type thing. I mean, yes, we don't know what's underneath, they don't really write a lot of detail, but even if it's hard cut that underneath, which a minor might not be, just the physical abilities of doing that parkour, that's a very impressive. So a lot, right there. Have you met spotmini or any of those robots in person?

Met spotmini last year in April at the Mars event that Jeff Bees was organized. They brought it out there and it was nicely falling around, Jeff. When Jeff left the room, they had it follow him along, which is pretty impressive. So I think there's some confidence to know that there's no learning going on in those robots. The psychology of it, so while knowing that, while knowing there's not, if there's any learning going on,

it's very limited. I met spot many earlier this year. And knowing everything that's going on Having one-on-one interaction. So I get to spend some time alone And there's a immediately a deep connection on the psychological level Even though you know the fundamentals how it works. There's something magical so Do you think about the psychology of interacting with robots in the physical world?

Even you just showed me the PR2, the robot. And there was a little bit something like a face. Had a little bit something like a face or something that immediately draws you to it. Do you think about that aspect of the robotics problem? Well, it's very hard with bread here. We'll give them a name. Berkeley Robot for the elimination of tedious tasks. It's very hard to not think of the robot as a person.

And it seems like everybody calls them a he, for whatever reason. But that also makes it more a person than if it was a it. And it seems pretty natural to think of it that way. This past we weekend really struck me I've seen Pepper many times on videos, but then I was at an event organized by, this was by Fidelity, and they had scripted Pepper to help moderate some sessions

and it's scripted Pepper to have the personality of a child a little bit. And it was very hard to not think of it as its own person in some sense, because it was just kind of jumping. It would just jump into conversation, making it very interactive. Moderately the same pepper would just jump in, hold on, how about me? Can I participate in this doing it? Just like, okay, this is like a person. And that was 100% scripted. And even then, it was hard not to have that sense of somehow, there is something there.

So, as we have robots interact in this physical world, is that a signal that could be used in reinforcement learning? You've worked a little bit in this direction, but do you think that that psychology can be somehow pulled in? So that's a question. I would say a lot of people ask. And I think part of why they ask is they're thinking about how unique are we really still ask people like after they see some results, they see a computer play go, they say a computer do this, that they're like, okay, but can it really have emotion? Can it really interact with us in that way?

And then once you're around robots, you already start feeling it. And I think that maybe methodologically, the way that I think of it is, if you run something like reinforcement learning, it's about optimizing some objective. And there's no reason that the objective couldn't be tied into how much does a person like interacting with this system and why could not the reinforcement learning system optimize for the robot being fun to be around and why wouldn't it then naturally become more and more interactive and more and more maybe like a person or like a pet. I don't know what it would exactly be, but more and more have those features and acquire

them automatically. As long as you can formalize an objective of what it means to like something, how you exhibit what's the ground truth, how do you get the reward from human? Because you have to somehow collect that information from you human. But you're saying if you can formulate as an objective, it can be learned. There is no reason it couldn't emerge through learning. And maybe one way to formulate as an objective, you wouldn't have to necessarily score it explicitly. So, standard rewards are numbers.

Numbers are hard to come by. This is a 1.5 or a 1.7 on some scale. It's very hard to do for a person. But much easier is for a person to say, okay, what you did the last five minutes was much nicer than what you did the previous five minutes. And that now gives a comparison. And in fact, there have been some results on that. For example, Paul Cristiano and collaborators at OpenAI had the hopper, Madoka hopper, one

leg at robot, the back flips. Purely from feedback, I like this better than that. That's kind of equally good. And after a bunch of interactions, it figured out what it was the person was asking for, namely a backflip. And so I think the same thing, it wasn't trying to do a backflip. It was just getting a score from the comparison score from the person based on... Person having a mind in their own mind.

I wanted to do a backflip, but the robot didn't know what it was supposed to be doing. It just knew that sometimes the person said this is better, this is worse, and then the robot figured out what the person was actually after was a backflip. And I imagine the same would be true for things like more intractive robots that the robot would figure out over time, oh, this kind of thing apparently is appreciated more than this other kind of thing. So when I first picked up Sutton's, Richard Sutton's reinforcement learning book, before this deep learning, before the re-emergence of neural networks

is a powerful mechanism for machine learning, RL seemed to me like magic. It was as beautiful. So that seemed like what intelligence is, RL reinforcement learning. So how do you think we can possibly learn anything about the world when the reward for the actions is delayed is so sparse?

Like, where is, why do you think RL works? Why do you think you can learn anything under such sparse rewards? Whether it's regular reinforcement learning or deeper reinforcement learning. What's your intuition? The kind of part of that is, why is RL? Why does it need so many samples, so many experiences to learn from? Because really what's happening is when you have a sparse reward, you do something maybe for like, I don't know, you take a hundred actions and then you get a reward. And maybe you get like a score of three. And I'm like, okay, three.

Not sure what that means. You go again and now you get two. And now you know that that sequence of hundred actions that you did the second time around, somehow was worse than the sequence of hundred actions you did the first time around. But that's half to none. Which one of those were better or worse? Some might have been good and bad and either one. And so that's why I need so many experiences. But once you have enough experiences effectively RLS teasing that apart is trying to say, okay, when what is consistently there when you get a higher reward and what's consistently there when you get a lower reward? And then the magic of,

and sometimes the policy grant update is to say, now let's update the neural network to make the actions that we're kind of present when things are good more likely and make the actions that are present when things are not as good less likely. So that is the counter point, but it seems like you would need to run it a lot

more than you do. Even though right now people could say that RL is very inefficient, but it seems to be way more efficient than one would imagine on paper that the simple updates to the policy, the policy grading that somehow you can learn is exactly, you just said, what are the common actions that seem to produce some good results, that that somehow can learn anything. It seems counterintuitive at least. Is there some intuition behind that?

Yeah, so I think there's a few ways to think about this. The way I tend to think about it mostly originally, and so when we started working on deep reinforcement learning here at Berkeley, which was maybe 2011, 12, 13, around that time, Challenge Shulman was a PhD student initially kind of driving it forward here. And kind of, the way we thought about it at the time was, if you think about rectified linear units or kind of rectifier type neural networks, what do you get?

You get something that's piecewise linear feedback control. And if you look at the literature, linear feedback control is extremely successful. It can solve many, many problems surprisingly well. I remember, for example, when we did helicopter flight, if you're in a stationary flight regime, not a non-stationary flight regime like hover, you can use linear feedback control to stabilize a helicopter, a very complex dynamical system, but the controller is relatively simple. And so I think that's a big part of it is that if you do feedback control, even though

the system you control can be very, very complex. Often relatively simple control architectures can already do a lot, but then also just linear is not good enough. And so one way you can think of these neural networks is that in some of these they tile the space, which people were already trying to do more by hand or with finite state machines. See, this linear controller here, this linear controller here, you know, on that work, learns to tile the spin, say, linear controller here, and not a linear controller here, but it's more subtle than that. And so it's benefiting from this linear control aspect, it's benefiting from the tiling, but it's somehow tiling it one dimension at a time. Because if let's say you have a two layer network, even that hidden

layer, you make a transition from active to inactive or the other way around. That is essentially one axis, but not axis aligned, but one direction that you change. And so you have this kind of very gradual tiling of the space where you have a lot of sharing between the linear controllers that tile the space. And that was always my intuition as to why to expect that this might work pretty well.

It's essentially leveraging the fact that linear feedback control is so good, but of course not enough. And this is a gradual timing of the space with linear feedback controls that share a lot of expertise across them. So that's really nice intuition. Do you think that scales to the more and more general problems of when you start going up the number of you start going up the number of dimensions when you start going down in terms of how often you get a clean reward signal. Does that intuition carry forward to those crazy or weird worlds that we think of as the real world? So I think where things get really tricky in the real world compared to the things we've looked at so far with great success in reinforcement learning is the time skills, which takes this to an extreme.

So, when you think about the real world, I mean, I don't know, maybe some students decided to do a PhD here, right? Okay, that's a decision, that's a very high level decision. But if you think about their lives, I mean, any person's life, it's a sequence of muscle fiber contractions and relaxation, and that's how you interact with the world. And that's a very high frequency control thing, but it's ultimately what you do, and how you affect the world.

Until I guess we have brain readings, you can maybe do it differently, but typically that's how you affect the world. Until I guess we have brain readings, you can maybe do it differently, but typically that's how you affect the world. And the decision of doing a PhD is like, so abstract relative to what you're actually doing in the world. And I think that's where credit assignment becomes just completely beyond what any current RL algorithm can do. And we need hierarchical reasoning at a level that is just not available at all yet. Where do you think we can pick up hierarchical reasoning by which mechanisms?

Yeah. So maybe let me highlight what I think the limitations are of what already was done. 20, 30 years ago. In fact, you'll find reasoning systems that reason over relatively long horizons, but the problem is that they were not grounded in the real world. So people would have to hand design some kind of logical, dynamical descriptions of the world and that didn't tie into perception. And so they didn't tie into real objects and so forth. And so that that was a big gap. Now with deep learning, we start having the ability to really see with sensors, process

that and understand what's in the world. And so it's a good time to try to bring these things together. One, I see a few ways of getting there. One way to get there would be to say, deep learning can get bolted on somehow to some of these more traditional approaches. Now, bolted on would probably mean you need to do some kind of end-to-end training where you say, my deep learning processing somehow leads to a representation that in term uses some kind of traditional underlying dynamical systems that can be used for planning.

And that's, for example, the direction of Yves Tamar and Thanard Kurutach here have been pushing with causal infogan, and of course other people too, that's one way. Can we somehow force it into the form factor that is amenable to reasoning? Another direction we've been thinking about for a long time and didn't make any progress on was more information theoretic approaches. So the idea there was that what it means to take high level action is to take and choose a latent variable now that tells you a lot about what's going to be the case in the future because that's what it means to take a high-level action. I say okay. What I decide I'm going to navigate to the gas station because I need to get gas from my car. Well, that'll not take five minutes to get there,

but the fact that I get there, I could already tell that from the high-level action I took much earlier. That, we had a very hard time getting success with, not saying it's dead end necessarily, but we had a lot of trouble getting that to work. And then we start revisiting the notion of what are we really trying to achieve. What we're trying to achieve is not necessarily hierarchy per se, but you can think about what is hierarchy give us. What it's we hope it would give us this better credit assignment. What is better credit assignment is giving us, it gives us faster learning. And so, faster learning is ultimately maybe what we're after.

And so, that's what we ended up with the RL-squared paper on learning to reinforcement learn, which at a time Rocky Dwan led. That's exactly the meta-learning approach, we don't know how to design hierarchy. We know what we want to get from it. Let's just end to an optimize for what we want to get from it and see if it might emerge. We saw things emerge. The amazing navigation had consistent motion down hallways, which is what you want. A hierarchical controller should say, I wanna go down this hallway, and then when there is an option to take a turn,

I can decide whether to take a turn or not, and repeat, even had the notion of, where have you been before or not, to not revisit places you've been before. It still didn't scale yet to the real world, kind of, in Harris, I think you had in mind, but it was some sign of life that maybe you can metal-earn these hierarchical concepts.

I mean, it seems like through these metal-earning concepts, get at what I think is one of the hardest and most important problems of AI, which is transfer learning. So it's generalization. How far along this journey towards building general systems are we? Being able to do transfer learning well. So there's some signs that you can generalize a little bit. But do you think we're on the right path or it's totally different break-throughs are needed to be able to transfer knowledge between different learned models. Yeah, I'm pretty torn on this.

And then I think there are some very impressive. Well, there's just some very impressive results already, right? I mean, I would say when even with the initial kind of big breakthrough in 2012 with Alex net, right, the initial, the initial thing of big breakthrough in 2012 with AlexNet, right? The initial thing is, okay, great. This does better on ImageNet, hence Image Recognition. But then immediately thereafter, there was of course the notion that, wow, what was learned on ImageNet and you now want to solve a new task, you can fine tune AlexNet for

new tasks. And that was often found to be the even bigger deal that you learned something that was reusable, which was not often the case before. Usually machine learning, you learn something for one scenario and that was it. And that's really exciting. I mean, that's just a huge application. That's probably the biggest success of transfer learning today. If in terms of scope and impact. That was a huge breakthrough. And then recently, I feel like similar kind of by scaling things up, it seems like this has been expanded upon. Like people training even bigger networks, they might transfer even better. If you looked at, for example, some of the opening eye results on language models and

some of the recent Google results on language models and some of the recent Google results on language models, they are learned for just prediction and then they get reused for other tasks. And so I think there is something there where somehow if you train a big enough model on enough things, it seems to transfer some deep mind results that I thought were very impressive, the unreal results, where it was learned to navigate Maze's some deep-minded results that I thought were very impressive, the unreal results, where

it was learned to navigate Maze's in ways where it wasn't just doing reinforcement learning, but it had other objectives, was optimizing for. So I think there's a lot of interesting results already. I think maybe where it's hard to wrap my head around this, do we extend, or when do we call something generalization, or the levels of generalization involved in these different tasks? All right.

So you draw this, by the way, just to frame things, I've heard you say somewhere, it's the difference in learning to master versus learning to generalize. That it's a nice line to think about, and I guess you're saying that it's a gray area of what learning to master and learning to generalize where one starts. I think I might have heard this.

I might have heard it somewhere else. And I think it might have been one of your interviews. And maybe the one with Yoshua Benjamin, not 100% sure. But I like the example. And I'm going to not sure who it was, but the example was essentially if you use current deep learning techniques, what we're doing to predict, let's say, the relative motion of our planets, it would do pretty well. But then now if a massive new mass enters our solar system,

it would probably not predict what would happen. And that's a different kind of generalization. That's a generalization that relies on the ultimate simplest, simplest explanation that we have available today to explain the motion of planets, whereas just pattern recognition could predict our current solar system motion pretty well.

No problem. And so I think that's an example of a kind of generalization that is a little different from what we've achieved so far. And it's not clear if just, you know, regularizing more, enforcing it to come up with a simpler, simpler, simpler way to say, look, this is not simple, but that's what physics researchers do, right,

to say, can I make this even simpler? How simple can I get this? What's the simplest equation that can researchers do, right? They say, can I make this even simpler? How simple can I get this? What's the simplest equation that can explain everything, right? The master equation for the entire dynamics of the universe, we haven't really pushed that direction as hard in deep learning, I would say. Not sure if it should be pushed, but it seems a kind of general addition you get from that that you don't get in our current methods so far. So I just talked to Vladimir Vapnik for example, who was a statistician, statistical learning, and he kind of dreams of creating the E equals, E equals MC squared for learning, right?

The general theory of learning. Do you think that's fruitless pursuit in near termterm within the next several decades? I think that's a really interesting pursuit. In the following sense, there is a lot of evidence that the brain is pretty modular. I wouldn't think of it as the theory,, maybe on the line theory, but more kind of the principle where there have been findings where people who are blind will use the part of the brain usually used for vision for other functions. And even after some kind of if people get rewired in some way, they might able to reuse parts of their brain for other functions.

And so what that suggests is some kind of modularity. And I think it is a pretty natural thing to strive for, to see, can we find that modularity? Can we find this thing? Of course, it's not every part of the brain is not exactly the same. Not everything can be rewired arbitrarily. But if you think of things like the Neocortex, which is a pretty big part of the brain, that seems fairly modular from what the finding

so far. Can you design something equally modular? And if you can just grow it, it becomes more capable, probably. I think that would be the kind of interesting underlying principle to shoot for that is not unrealistic. Do you think you prefer math or empirical trial and error for the discovery of the essence of what it means to do something intelligent? So we're going to force some learning about these both groups, right?

Prove that something converges, prove the bounds, and then at the same time, a lot of those successes are, well, let's try this and see if it works. So which do you gravitate towards? How do you think of those two parts of your brain? So maybe I would prefer we could make the progress with mathematics. And the reason maybe I would prefer that is because often if you have something you can mathematically formalize, you can leapfrog a lot of experimentation. And experimentation takes a long time to get through. And a lot of trial and error kind of reinforcement in your research process. But you need to do a lot of trial and error before you get to success. So if you can leapfrog that to my mind, that's what the math is about.

And hopefully once you do a bunch of experiments, you start seeing a pattern. You can do some derivations that leapfrog some experiments. But I agree with you. I mean, in practice, a lot of the progress has been such that we have not been able to find the math that allows you to leapfrog ahead. And we are kind of making gradual progress once to about a time, a new experiment here, a new experiment there that gives us new insights and gradually building up,

but not getting to something yet where we're just, OK, here's an equation that now explains how, you know, that would be, it have been two years of experimentation to get there, but this tells us what the result's going to be. Unfortunately, not so much yet. Not so much yet, but your hope is there. In trying to teach robots or systems to do everyday tasks or even in simulation, what do you think you're more excited about? Emutation learning or self-play. So letting robots learn from humans, or letting robots plan their own to try to figure out in

their own way and eventually interact with humans or solve whatever problem is. What's more exciting to you? What's more promising, you think, is a research direction. So when we look at self-play, what's so beautiful about it is, goes back to kind of the challenges in reinforcement learning. So the challenge in reinforcement is getting signal. And if you don't never succeed, you don't get any signal. In self-play, you're on both sides. So one of you succeeds. And the beauty is also one of you fails. And so you see the contrast. You see the one version of me that did better than the other version.

And so every time you play yourself, you get signal. And so whenever you can turn something into self-play, you're in a beautiful situation where you can naturally learn much more quickly than in most other reinforcement environments. So I think if somehow we can turn more reinforcement learning problems into self-play formulations, that would go really, really far. So far, self-play has been largely around games

where there is natural opponents. But if we could do self-play for other things, and let's say, I don't know, a robot learns to build a house. I mean, that's a pretty advanced thing to try to do for a robot, but maybe it tries to build a hut or something. If that can be done through self-play, it would learn a lot more quickly if somebody can figure it out. And I think that would be something where it goes closer to kind of the mathematical leapfrogging, where somebody figures out of formalism too. So, okay, any RL problem by playing this in this idea, you can turn it into a self-play

problem where you get signal a lot more easily. Reality is many problems we don't know how to turn to self-play. And so either we need to provide detailed reward. That doesn't just reward for achieving a goal, but rewards for making progress, and that becomes time consuming. And once you're starting to do that, let's say you want a robot to do something, you need to give all this detailed reward, well, why not just give it demonstration?

Because why not just show the robot? And now the question is, how do you show the robot? One way to show is to tally operate the robot. And then the robot really experiences things. And that's nice, because that's really high signal to noise ratio there. And we've done a lot of that. And you teach your robot skills in just 10 minutes,

you can teach your robot a new basic skill. I could pick up the bottle place somewhere else. That's a skill, no matter where the bottle starts, maybe it always goes on to a target or something. That's fairly easy to teach your robot with tele-op. Now, what's even more interesting if you can now teach your robot through a third person learning, where the robot watches you do something and doesn't experience it, but just watches it and says, okay, well, if you're showing me that, that means I should be doing this. And I'm not going to be using your hand because I don't get to control your hand, but I'm

going to use my hand. I do that mapping. And so that's where I think one of the big breakthroughs has happened this year. This was led by Chelsea Finn here. It's almost like learning a machine translation for demonstrations where you have a human demonstration and the robot learns to translate it into what it means for the robot to do it.

And that was a meta-learning formulation. Learn from one to get the other. And that, I think, opens up a lot of opportunities to learn a lot more quickly. So my focus is on autonomous vehicles. Do you think this approach of third-person watching is the autonomous driving is amenable to this kind of approach? So for autonomous driving, I would say it's third-person is slightly easier. And the reason I'm going to say it's slightly

easier to do with third-person is because the hard dynamics are very well understood. So the easier than first person you mean or I think I think the distinction between third person and first person steering wheel and or maybe let me put it differently. How to get from a point where you are now to a point, let's say a couple meters in front of you, and that's a problem that's very well understood. And that's the only distinction between a third and first person there. Whereas with the robot manipulation, interaction forces are very complex and it's still a very different thing. For autonomous driving, I think there is still the question, imitation versus RL. So imitation gives you a lot more signal. I think where imitation is lacking and needs some extra machinery is it doesn't, and it's normal format, doesn't think about goals or objectives.

Of course, there are versions of imitation learning, in verse reinforcement learning type imitation learning, which also thinks about goals. I think then we're getting much closer, but I think it's very hard to think of a fully reactive, hard, generalizing, well, if it really doesn't have a notion of objectives to generalize well to the kind of

Generality that you would want. You'd want more than just that reactivity that you get from just behavioral Cloning slash supervised learning. So a lot of the work, whether it's self-play or even imitation learning, would benefit significantly From simulation, from effective simulation, and you're doing a lot of stuff in the physical world and in simulation. Do you have hope for greater and greater power of simulation being boundless eventually to where most of what we need to operate in the physical world could be simulated to a degree that's directly transferable to the physical world, are we still very far away from that? So, I think we could even rephrase that question in some sense. Please.

And now, so the power of simulation, right, as simulators get better and better, of of course becomes stronger and we can learn more in simulation. But there's also another version which is where you say the simulator doesn't even have to be that precise. As long as it's somewhat representative and instead of trying to get one simulator that is sufficiently precise to learn in and transfer really well to the real world, I'm going to build many simulators. Ensemble of simulators. Ensemble of simulators. Not any single one of them is sufficiently representative of the real world, such that it would work

if you train in there, but if you train in all of them, then there is something that's good in all of them. The real world will just be, you know, another one. I've done that. You know, not identical to any one of them, you know another one of them. That's you know not identical to any one of them But just another one of them now the sample from the distribution of simulators. We do live in a simulation So this is just one one other one. I'm not sure about that. But yeah Definitely a very advanced simulator if it is yeah, it's pretty good one

I've talked to those two Russell. It's something you think about a little bit too. Of course, you're like really trying to build these systems, but do you think about the future of AI? A lot of people have concern about safety. How do you think about AI safety? As you build robots that are operating the physical world, what is, yeah, how do you approach this problem in an engineering kind of way in a systematic way? So when a robot is doing things, you kind of have a few notions of safety to worry about. One is that the robot is physically strong and of course could do a lot of damage, same for cars, which we can think of as robots do in some way. And this could be completely unintentional.

So it could be not the kind of long-term AI safety concerns that, okay, AI is smarter than us and now what do we do, but it could be just very practical. Okay, this robot, if it makes a mistake, whether the result's going to be, of course, simulation comes in a lot there to test in simulation. It's a difficult question.

And I'm always wondering, like I always wonder, let's say you look at, let's go back to driving, because a lot of people know driving well, of course. What do we do to test somebody for driving, right? Get a driver's license. What do they really do? I mean, you fill out some tests. And then you drive, and I mean, for a few minutes, it's suburban California, that driving test is just you drive around the block, pullover, you do a stop sign successfully. And then, you know, you have pullover again and you're pretty much done. And you're like, okay, if a self driving car did that, would you trust it that it can drive? And I'd be like, no, that's not enough for me to trust it.

But somehow for humans, we've figured out that somebody being able to do that is representative of them being able to do a lot of other things. And so I think somehow for humans, we figured out representative tests of what it means if you can do this, what you can really do. Of course, testing humans, humans don't want to be tested at all times.

Self-driving cars or robots could be tested more often, probably you can have replicants that get tested and are known to be identical because they use the same neural net and so forth. But still, I feel like we don't have this kind of unit tests or proper tests for robots. And I think there's something very interesting to be thought about there, especially as you update things. Your software improves-draight improves, you have a better self-driving car suite,

you update it. How do you know it's indeed more capable on everything than what you had before that you didn't have any bad things creep into it? So I think that's a very interesting direction of research that there is no real solution yet, except that's somehow for humans we do, because we say, okay, you have a driving test, you passed, you can go on the road now, and humans have accents every like a million or 10 million miles, something pretty phenomenal compared to that short test that is being done. So let me ask, you've mentioned the Andrew Ang, by example, showed you the value of kindness. Do you think the space of policies, good policies for humans and for AI is populated by

policies that with kindness are ones that are the opposite. Exploitation, even evil. So if you just look at the sea of policies we operate under as human beings or if AI system had to operate in this real world, do you think it's really easy to find policies that are full of kindness like we naturally fall into them or is it like a very hard optimization problem? I mean there is kind of two optimizations happening for humans, right? So for humans, there is kind of the very long-term optimization, which evolution has done for us, and we're kind of predisposed to like certain things.

And that's in some sense what makes our learning easier, because I mean, we know things like pain and hunger and thirst. And the fact that we know about those is not something that we were taught. That's kind of innate. When we're hungry, we're unhappy. When we're thirsty, we're unhappy. When we have pain, we're unhappy.

And ultimately, evolution built that into us to think about those things. And so I think there is a notion that it seems somehow humans evolved in general to prefer to get along in some ways, but at the same time also to be very territorial and kind of centric to their own tribe. It seems like that's the kind of space we converge on to. I mean, I'm not an expert in anthropology, but it seems like we're very kind of

good within our own tribe, but need to be taught to be nice to other tribes. Well, if you look at Stephen Pinker, he highlights this pretty nicely in better angels of our nature, where he talks about violence, decreasing over time consistently. So whatever tension, whatever teams we pick, it seems that the long arc of history goes towards us getting along more and more. So I hope so. So do you think that, do you think it's possible to teach RL based robots,

this kind of kindness, this kind of ability to interact with humans, this kind of policy, even to, let me ask a fun one. Do you think it's possible to teach RL-based robot to love a human being and to inspire that human to love the robot back? So to like, RL-based algorithm that leads to a happy marriage. That's an interesting question. Maybe I'll answer it with with another question, right?

Because I mean, it's a but I'll come back to it. So another question can have is okay. I mean, how close does some people's happiness get from interacting with just a really nice dog? Like, I mean, dogs, you come home. That's what dogs it they greet you. They're excited Makes you happy when you come home to your dog. You're just like, okay, this is exciting. They're always happy when I'm here I mean if they don't greet you because maybe whatever Your partner took him on a trip or something you might not be nearly as happy when you get home, right and so the kind of It seems like the level of reasoning a dog has is pretty sophisticated,

but then it's still not yet at the level of human reasoning. And so it seems like we don't even need to achieve human love reasoning to get very strong affection with humans. And so my thinking is, why not? Why couldn't we achieve the kind of level of affection that humans feel among each other or with friendly animals and so forth? It's a question. Is it a good thing for us or not? That's another thing, right? Because I mean

But I don't see why not why not yeah, Yeah. So Elon Musk says love is the answer. Maybe he should say love is the objective function. And then RL is the answer. Right. Oh, maybe. Peter, thank you so much. I don't want to take up more of your time. Thank you so much for talking today.

Well, thanks for coming by. Great to have you visit. you