Roger Penrose: Physics of Consciousness and the Infinite Universe

00:00:00.000 | The following is a conversation with Roger Penrose,

00:00:02.760 | physicist, mathematician, and philosopher

00:00:05.320 | at University of Oxford.

00:00:07.040 | He has made fundamental contributions in many disciplines

00:00:10.840 | from the mathematical physics of general relativity

00:00:13.320 | and cosmology to the limitations

00:00:15.800 | of a computational view of consciousness.

00:00:18.680 | In his book, "The Emperor's New Mind,"

00:00:20.840 | Roger writes that, quote,

00:00:22.840 | "Children are not afraid to pose basic questions

00:00:26.080 | "that may embarrass us as adults to ask."

00:00:29.900 | In many ways, my goal with this podcast

00:00:32.000 | is to embrace the inner child

00:00:33.680 | that is not constrained by how one should behave,

00:00:36.520 | speak, and think in the adult world.

00:00:40.120 | Roger is one of the most important minds of our time,

00:00:44.760 | so it's truly a pleasure and an honor to talk with him.

00:00:48.300 | This conversation was recorded

00:00:50.600 | before the outbreak of the pandemic.

00:00:52.920 | For everyone feeling the medical, psychological,

00:00:55.800 | and financial burden of the crisis,

00:00:57.740 | I'm sending love your way.

00:00:59.760 | Stay strong.

00:01:00.840 | We're in this together.

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00:03:46.440 | And now, here's my conversation with Roger Penrose.

00:03:50.660 | You mentioned in conversation with Eric Weinstein

00:03:54.240 | on the Portal podcast that 2001 Space Odyssey

00:03:57.620 | is your favorite movie.

00:03:58.980 | Which aspect, if you could mention,

00:04:02.100 | of its representation of artificial intelligence,

00:04:05.100 | science, engineering connected with you?

00:04:07.740 | - There are all sorts of scenes there which are so amazing.

00:04:11.460 | And how they, science was so well done.

00:04:14.820 | I mean, people say, oh no, Interstellar,

00:04:16.900 | it's this amazing movie which is the most scientific movie.

00:04:21.700 | I thought it's not a patch on 2001.

00:04:23.780 | I mean, 2001, they really went into all sorts of details.

00:04:29.260 | And they're getting the free fall well done and everything.

00:04:33.200 | I thought it was extremely well done.

00:04:35.940 | - So just the details were mesmerizing in terms of--

00:04:38.900 | - And also things like the scene where at the beginning

00:04:43.180 | they have these sort of human ancestors

00:04:45.700 | which are sort of apes becoming humans.

00:04:49.540 | - The monolith.

00:04:50.820 | - Yes, and well, it's the one where he throws the bone

00:04:53.880 | up into the air and then it becomes this,

00:04:56.300 | I mean, that's an amazing sequence there.

00:05:00.140 | - What do you make of the monolith?

00:05:01.860 | Does it have any scientific or philosophical meaning to you,

00:05:06.140 | this kind of thing that sparks innovation?

00:05:08.220 | - Not really. (laughs)

00:05:10.160 | That comes from Arthur C. Clarke.

00:05:12.260 | I was always a great fan of Arthur C. Clarke.

00:05:14.260 | - So it's just a nice plot device.

00:05:16.020 | - Yeah, oh, that plot is excellent, yes.

00:05:18.140 | - So Hal 9000 decides to get rid of the astronauts

00:05:22.020 | because he, it, she, believes that they will interfere

00:05:26.900 | with the mission.

00:05:27.740 | - That's right.

00:05:28.560 | No, well, there you are, it's this view.

00:05:30.360 | I don't know whether I disagree with it,

00:05:31.580 | 'cause in a certain sense it was telling you it's wrong.

00:05:34.340 | See, the machine seemed to think it was superior

00:05:39.460 | to the human, and so it was entitled

00:05:44.260 | to get rid of the human beings and run the show itself.

00:05:47.380 | - Well, do you think Hal did the right thing?

00:05:49.460 | Do you think Hal's flawed, evil?

00:05:52.020 | Or if we think about systems like Hal,

00:05:55.340 | would we want Hal to do the same thing in the future?

00:05:58.020 | What was the flaw there?

00:05:58.940 | - Well, you're basically touching on questions, you see.

00:06:02.260 | Is one supposed to believe that Hal was actually conscious?

00:06:07.660 | I mean, it was played rather that way,

00:06:10.180 | as though Hal was a conscious being.

00:06:13.540 | - Because Hal showed some pain, some,

00:06:18.540 | Hal appeared to be cognizant of what it means to die.

00:06:23.780 | - Yes, yes. - And therefore had that.

00:06:26.060 | - That's true, yes.

00:06:27.180 | - An inkling of consciousness.

00:06:28.260 | - Yeah, I mean, I'm not sure that aspect of it

00:06:31.220 | was made completely clear, whether Hal was really

00:06:34.060 | just a very sophisticated computer,

00:06:37.160 | which really didn't actually have these feelings

00:06:39.340 | and somehow, but you're right,

00:06:42.220 | it didn't like the idea of being turned off.

00:06:44.700 | - How does it change things if Hal was or wasn't conscious?

00:06:48.820 | - Well, it might say that it would be wrong to turn it off

00:06:53.140 | if it was actually conscious.

00:06:55.220 | I mean, these questions arise if you think,

00:06:57.380 | I mean, AI, one of the ideas,

00:07:02.780 | it's sort of a mixture in a sense, you say.

00:07:05.300 | If it's trying to do everything a human can do

00:07:08.160 | and if you take the view that consciousness

00:07:11.520 | is something which would come along

00:07:13.400 | when the computer is sufficiently complicated,

00:07:16.200 | sufficiently whatever criterion you use

00:07:19.280 | to characterize its consciousness

00:07:23.680 | in terms of some computational criterion.

00:07:28.640 | - So how does consciousness change our evaluation

00:07:33.600 | of the decision that Hal made?

00:07:35.820 | - Well, I guess I was trying to say

00:07:36.780 | that people are a bit confused about this

00:07:38.940 | because if they say these machines will become conscious,

00:07:42.100 | but just simply because it's a degree of computation

00:07:45.300 | and when you get beyond that certain degree of computation,

00:07:48.260 | it will become conscious,

00:07:49.420 | then of course you have all these problems.

00:07:52.340 | I mean, you might say, well, one of the reasons

00:07:54.020 | you're doing AI is because you understand

00:07:56.500 | a device out to some distant planet

00:07:59.040 | and you don't want to send a human out there

00:08:01.140 | 'cause then you'd have to bring it back again

00:08:02.780 | and that costs you far more than just sending it there

00:08:05.860 | and leaving it there.

00:08:07.060 | But if this device is actually a conscious entity,

00:08:10.020 | then you have to face up to the fact that that's immoral.

00:08:13.060 | And so the mere fact that you're making some AI device

00:08:17.780 | and thinking that removes your responsibility to it

00:08:24.060 | would be incorrect.

00:08:25.820 | And so this is a sound flaw in that kind of viewpoint.

00:08:29.700 | I'm not sure how people who take it very seriously,

00:08:34.200 | I mean, I had this curious conversation with,

00:08:37.700 | I'm going to forget names, I'm afraid,

00:08:40.780 | because this is what happens to me at the wrong moment,

00:08:43.860 | Hofstadter, Douglas Hofstadter.

00:08:45.820 | - Douglas Hofstadter, yeah.

00:08:46.660 | - And he'd written this book.

00:08:48.860 | - God Aleshapak.

00:08:49.700 | - God Aleshapak, which I liked,

00:08:50.520 | I thought it was a fantastic book.

00:08:52.300 | But I didn't agree with his conclusion

00:08:55.700 | from Godel's theorem, I think he got it wrong, you see.

00:08:58.580 | Well, I'll just tell you my story, you see,

00:09:01.220 | 'cause I'd never met him.

00:09:02.700 | And then I knew I was going to meet him,

00:09:04.700 | the occasion I realized he was coming in,

00:09:06.860 | he wanted to talk to me, and I said, "That's fine."

00:09:09.140 | And I thought in my mind,

00:09:10.340 | "Well, I'm going to paint him into a corner," you see,

00:09:12.580 | 'cause I'll use his arguments to convince him

00:09:15.760 | that certain numbers are conscious.

00:09:19.180 | You know, some integers, large enough integers

00:09:21.140 | are actually conscious.

00:09:22.620 | And this was going to be my reductio ad absurdum.

00:09:25.380 | And so I started having this argument with him,

00:09:26.900 | and he simply leapt into the corner.

00:09:28.700 | He didn't even need to be painted into it.

00:09:31.060 | He took the view that certain numbers were conscious.

00:09:33.900 | I thought that was a reductio ad absurdum,

00:09:35.820 | but he seemed to think it was

00:09:37.180 | a perfectly reasonable point of view.

00:09:38.900 | - Without the absurdum there.

00:09:40.660 | - Yes.

00:09:41.580 | - Interesting, but the thing you mentioned about Hal

00:09:44.620 | is the intuition that a lot of the people,

00:09:46.980 | at least in the artificial intelligence world,

00:09:48.920 | had and have, I think.

00:09:51.540 | They don't make it explicit,

00:09:52.740 | but that if you increase the power of computation,

00:09:56.860 | naturally consciousness will emerge.

00:09:58.980 | - Yes, I think that's what they think.

00:10:00.340 | But basically that's 'cause they can't think

00:10:01.860 | of anything else.

00:10:02.780 | - Well, that's right.

00:10:03.600 | - And so it's a reasonable thing.

00:10:05.340 | I mean, you think, "What does the brain do?"

00:10:06.580 | Well, it does do a lot of computation.

00:10:09.180 | I think most of what you actually call computation

00:10:11.540 | is done by the cerebellum.

00:10:13.300 | I mean, this is one of the things

00:10:15.680 | that people don't much mention.

00:10:17.900 | I mean, I come to this subject from the outside,

00:10:19.820 | and certain things strike me,

00:10:21.940 | which you hardly ever hear mentioned.

00:10:24.760 | I mean, you hear mentioned about the left-right business,

00:10:28.460 | the move your right arm,

00:10:30.360 | that's the left side of the brain, and so on,

00:10:33.100 | and all that sort of stuff.

00:10:34.980 | And it's more than that.

00:10:36.820 | If you have these plots of different parts of the brain,

00:10:40.500 | there are two of these,

00:10:41.340 | these things called the homunculi,

00:10:43.360 | which you see these pictures of a distorted human figure

00:10:47.540 | and showing different parts of the brain

00:10:51.500 | controlling different parts of the body.

00:10:53.180 | And it's not simply things like,

00:10:55.940 | okay, the right hand is controlled

00:10:58.080 | and both sensory and motor on the left side,

00:11:03.080 | left hand on the right side.

00:11:04.880 | It's more than that.

00:11:06.000 | Vision is at the back, basically.

00:11:08.660 | Your feet at the top.

00:11:10.180 | And it's as though it's about the worst organization

00:11:13.100 | you could imagine.

00:11:13.940 | - Right, yeah.

00:11:14.880 | - So it can't just be a mistake in nature.

00:11:17.580 | There's something going on there.

00:11:19.520 | And this is made more pronounced

00:11:22.700 | when you think of the cerebellum.

00:11:24.340 | The cerebellum has,

00:11:27.600 | when I was first thinking about these things,

00:11:29.400 | I was told that it had half as many neurons

00:11:32.060 | or something like that, comparable.

00:11:33.980 | And now they tell me it's got far more neurons

00:11:36.540 | than the cerebrum.

00:11:38.260 | The cerebrum is this sort of convoluted thing at the top

00:11:41.000 | people always talk about.

00:11:42.060 | Cerebellum is this thing

00:11:43.540 | just looks a bit like a ball of wool

00:11:45.420 | right at the back underneath.

00:11:47.140 | - Yeah.

00:11:47.980 | - It's got more neurons.

00:11:49.500 | It's got more connections.

00:11:51.660 | Computationally, it's got much more going on

00:11:55.140 | than the cerebrum.

00:11:57.140 | But as far as we know, although it's slightly controversial,

00:12:01.420 | the cerebellum is entirely unconscious.

00:12:04.860 | So the actions, you have a pianist

00:12:07.340 | who plays an incredible piece of music

00:12:09.060 | and you think of,

00:12:10.900 | and he moves his little finger into this little key

00:12:13.580 | to get it hit it just the right moment.

00:12:15.940 | Does he or she consciously will that movement?

00:12:20.800 | No.

00:12:21.640 | Okay, the consciousness is coming in.

00:12:24.700 | It's probably to do with the feeling

00:12:26.100 | of the piece of music that's being performed

00:12:28.820 | and that sort of thing, which is going on.

00:12:31.260 | But the details of what's going on are controlled.

00:12:34.140 | I would think almost entirely by the cerebellum.

00:12:37.560 | That's where you have this precision

00:12:40.380 | and the really detailed.

00:12:44.060 | Once you get, I mean, you think of a tennis player

00:12:47.260 | or something, does that tennis player think exactly how to,

00:12:50.260 | which muscles should be moved in what direction?

00:12:52.640 | And so, no, of course not.

00:12:54.380 | But he or she will maybe think,

00:12:56.240 | well, if the ball is angled in such a way in that corner,

00:12:59.340 | that will be tricky for the opponent.

00:13:02.020 | And the details of that are all done largely

00:13:07.020 | with the cerebellum.

00:13:08.740 | That's where all the precise motions, but it's unconscious.

00:13:13.060 | - So why is it interesting to you

00:13:14.420 | that so much computation is done in the cerebellum

00:13:17.940 | and yet it is unconscious?

00:13:19.340 | - Because it's the view that somehow it's computation,

00:13:24.340 | which is producing the consciousness.

00:13:27.340 | And here you have an incredible amount

00:13:30.740 | of computation going on.

00:13:32.100 | And as far as we know, it's completely unconscious.

00:13:35.820 | So why, what's the difference?

00:13:39.460 | And I think it's an important thing.

00:13:41.860 | What's the difference?

00:13:42.960 | Why is the cerebrum, all this very peculiar stuff

00:13:47.620 | that very hard to see on a computational perspective,

00:13:51.300 | like having everything have to cross over

00:13:53.980 | onto the other side and do something

00:13:55.620 | which looks completely inefficient.

00:13:57.380 | And you've got funny things like the frontal lobe

00:14:01.540 | and the, what do we call the lobes?

00:14:04.680 | And the place where they come together,

00:14:06.640 | you have the different parts, the control,

00:14:12.340 | you see one to do with motor

00:14:13.740 | and the other to do with sensory.

00:14:16.360 | And they're sort of opposite each other

00:14:17.920 | rather than being connected by,

00:14:19.460 | it's not as though you've got electrical circuits.

00:14:23.480 | There's something else going on there.

00:14:25.380 | So it's just the idea that it's like a complicated computer

00:14:30.280 | just seems to me to be completely missing the point.

00:14:34.600 | There must be a lot of computation going on,

00:14:37.400 | but the cerebellum seems to be much better at doing that

00:14:40.320 | than the cerebrum is.

00:14:41.520 | - So for sure, I think what explains it,

00:14:45.460 | it's like half hope and half we don't know what's going on

00:14:49.720 | and therefore from the computer science perspective,

00:14:52.440 | you hope that a Turing machine can be perfectly,

00:14:56.360 | can achieve general intelligence.

00:14:58.040 | - Well, you have this wonderful thing about Turing

00:15:02.240 | and Godel and Kirch and Currie and various people,

00:15:07.240 | particularly Turing and I guess Post was the other one.

00:15:11.680 | These people who developed the idea

00:15:14.360 | of what a computation is.

00:15:15.900 | And there were different ideas of what a computer,

00:15:19.880 | developed differently.

00:15:20.720 | I mean, Church's way of doing it

00:15:21.840 | was very different from Turing's,

00:15:24.620 | but then they were shown to be equivalent.

00:15:26.800 | And so the view emerged that what we mean by computation

00:15:30.840 | is a very clear concept.

00:15:33.860 | And one of the wonderful things that Turing did

00:15:37.860 | was to show that you could have

00:15:40.180 | what we call the universal Turing machine.

00:15:43.240 | It's you just have to have a certain finite device.

00:15:46.320 | Okay, it has to have an unlimited storage space,

00:15:48.600 | which is accessible to it.

00:15:50.180 | But the actual computation, if you like,

00:15:51.960 | is performed by this one universal device.

00:15:55.980 | And so the view comes away,

00:15:57.720 | well, you have this universal Turing machine

00:16:01.320 | and maybe the brain is something like that,

00:16:03.840 | a universal Turing machine.

00:16:05.160 | And it's got maybe not unlimited storage,

00:16:08.600 | but a huge storage accessible to it.

00:16:12.680 | And this model is one,

00:16:14.400 | which is what's used in ordinary computation.

00:16:17.400 | It's a very powerful model.

00:16:19.280 | And the universalness of computation is very useful.

00:16:24.280 | You could have some problem

00:16:26.160 | and you may not see immediately

00:16:27.560 | how to put it onto a computer,

00:16:29.120 | but if it is something of that nature,

00:16:32.200 | then there are all sorts of sub-programs

00:16:36.200 | and sub-routines when all the,

00:16:37.600 | I mean, I learned a little bit of computing

00:16:39.000 | when I was a student, but not very much.

00:16:42.560 | But it was enough to get the general ideas.

00:16:45.080 | - And there's something really pleasant

00:16:46.480 | about a formal system like that,

00:16:49.240 | where you can start discussing about what's provable,

00:16:51.440 | what's not, these kinds of things.

00:16:52.760 | - And you've got a notion, which is an absolute notion,

00:16:55.320 | this notion of computability.

00:16:56.800 | And you can address when things are,

00:17:00.240 | mathematical problems are computably solvable

00:17:02.800 | and which aren't.

00:17:04.120 | And it's a very beautiful area of mathematics

00:17:06.720 | and it's a very powerful area of mathematics.

00:17:09.680 | And it underlies the whole sort of,

00:17:13.600 | what would one say,

00:17:15.440 | the principles of computing machines that we have today.

00:17:19.680 | - Could you say what is Gato's incompleteness theorem

00:17:22.800 | and how does it, maybe also say,

00:17:24.880 | is it heartbreaking to you?

00:17:26.500 | And how does it interfere with this notion of computation

00:17:31.080 | and consciousness?

00:17:32.680 | - Sure.

00:17:33.520 | Well, the ideas, basically,

00:17:35.400 | ideas which I formulated in my first year

00:17:39.120 | as a graduate student in Cambridge.

00:17:41.560 | I did my undergraduate work in mathematics in London

00:17:44.680 | and I had a colleague, Ian Percival.

00:17:47.460 | We used to discuss things like computational

00:17:49.760 | and logical systems quite a lot.

00:17:52.280 | I'd heard about Godel's theorem.

00:17:53.680 | I was a bit worried by the idea that it seemed to say

00:17:55.880 | there were things in mathematics that you could never prove.

00:17:59.640 | And so when I went to Cambridge as a graduate student,

00:18:03.140 | I went to various courses.

00:18:06.040 | You see, I was doing pure mathematics.

00:18:08.540 | I was doing algebraic geometry of a sort,

00:18:11.960 | little bit different from what my supervisor and people,

00:18:15.280 | but it was algebraic geometry.

00:18:17.480 | And I was interested,

00:18:20.240 | I got particularly interested in three lecture courses

00:18:24.840 | that were nothing to do with what I was supposed

00:18:27.000 | to be doing.

00:18:28.200 | One was a course by Herman Bondi

00:18:30.520 | on Einstein's general theory of relativity,

00:18:33.440 | which was a beautiful course.

00:18:34.600 | He was an amazing lecturer,

00:18:37.480 | brought these things alive, absolutely.

00:18:40.240 | Another was a course on quantum mechanics

00:18:43.340 | given by the great physicist, Paul Dirac.

00:18:46.500 | Very beautiful course in a completely different way.

00:18:50.540 | It was very kind of organized

00:18:52.420 | and never got excited about anything seemingly.

00:18:56.380 | But it was extremely well put together

00:19:00.620 | and I found that amazing too.

00:19:03.300 | Third course that was nothing to do

00:19:04.740 | with what I should be doing

00:19:05.860 | was a course on mathematical logic.

00:19:08.100 | I got excited, as I say,

00:19:10.020 | my discussions with Ian Percival.

00:19:12.860 | - Was the incompleteness theorem already deeply

00:19:15.980 | within mathematical logic space?

00:19:18.740 | Were you introduced to it?

00:19:20.220 | - I was introduced to it in detail by the course by Steen.

00:19:23.880 | And he, it was two things he described

00:19:27.820 | which were very fundamental to my understanding.

00:19:31.040 | One was Turing machines

00:19:33.540 | and the whole idea of computability and all that.

00:19:35.820 | So that was all very much part of the course.

00:19:38.260 | The other one was the Godel theorem.

00:19:41.420 | And it wasn't what I was afraid it was

00:19:43.500 | to tell you there were things in mathematics

00:19:45.180 | you couldn't prove.

00:19:46.180 | It was basically,

00:19:49.940 | and he phrased it in a way which often people didn't.

00:19:53.100 | And if you read Douglas Hofstadter's book,

00:19:54.860 | he doesn't, you see.

00:19:56.420 | But Steen made it very clear.

00:19:58.220 | And also in a sort of public lecture

00:20:01.140 | that he gave to a mathematical,

00:20:02.900 | I think it may be the Adams Society,

00:20:04.340 | one of the mathematical undergraduate societies.

00:20:07.180 | And he made this point again very clearly.

00:20:09.500 | That if you've got a formal system of proof,

00:20:11.820 | so suppose what you mean by proof

00:20:15.180 | is something which you could check with a computer.

00:20:19.180 | So to say whether you've got it right or not,

00:20:21.260 | you've got a lot of steps.

00:20:22.380 | Have you carried this computational procedure?

00:20:25.980 | Well, following the proof, steps of the proof correctly,

00:20:30.560 | that can be checked by an algorithm,

00:20:33.900 | by a computer.

00:20:35.460 | So that's the key thing.

00:20:38.820 | Now what you have to,

00:20:40.740 | now you see, is this any good?

00:20:44.440 | If you've got an algorithmic system

00:20:47.300 | which claims to say, yes, this is right,

00:20:49.980 | this you've proved it correctly, this is true.

00:20:52.660 | If you've proved it, if you made a mistake,

00:20:54.860 | it doesn't say it's true or false,

00:20:56.020 | but if you've done it right,

00:20:57.980 | then the conclusion you've come to is correct.

00:21:02.020 | Now you say, why do you believe it's correct?

00:21:03.900 | Because you've looked at the rules and you said,

00:21:05.460 | well, okay, that one's all right,

00:21:06.780 | yeah, that one's all right.

00:21:07.620 | What about, oh, I'm not sure.

00:21:08.700 | Yeah, I see, I see why it's all right.

00:21:10.100 | Okay, you go through all the rules.

00:21:12.020 | You say, yes, following those rules,

00:21:13.840 | if it says, yes, it's true, it is true.

00:21:16.940 | So you've got to make sure that these rules

00:21:19.940 | are ones that you trust.

00:21:21.980 | If you follow the rules and it says it's a proof,

00:21:25.020 | is the result actually true?

00:21:27.620 | And that your belief that it's true

00:21:29.680 | depends upon looking at the rules

00:21:31.780 | and understanding them.

00:21:33.120 | Now, what Gödel shows, that if you have such a system,

00:21:38.500 | then you can construct a statement

00:21:41.420 | of the very kind that it's supposed to look at,

00:21:43.820 | a mathematical statement,

00:21:45.700 | and you can see by the way it's constructed

00:21:48.960 | and what it means that it's true,

00:21:52.480 | but not provable by the rules that you've been given.

00:21:57.940 | And it depends on your trust in the rules.

00:22:00.900 | Do you believe that the rules only give you truths?

00:22:03.260 | If you believe the rules only give you truths,

00:22:05.200 | then you believe this other statement is also true.

00:22:08.540 | I found this absolutely mind-blowing.

00:22:10.820 | When I saw this, it blew my mind.

00:22:13.620 | I thought, my God, you can see that this statement is true.

00:22:17.900 | It's as good as any proof

00:22:19.820 | because it only depends on your belief

00:22:22.660 | in the reliability of the proof procedure,

00:22:25.140 | that's all it is,

00:22:26.540 | and understanding that the coding is done correctly,

00:22:30.100 | and it enables you to transcend that system.

00:22:32.920 | So whatever system you have,

00:22:36.260 | as long as you can understand what it's doing

00:22:39.020 | and why you believe it only gives you truths,

00:22:41.980 | then you can see beyond that system.

00:22:43.780 | Now, how do you see beyond it?

00:22:46.220 | What is it that enables you to transcend that system?

00:22:51.220 | Well, it's your understanding

00:22:53.260 | of what the system is actually saying

00:22:55.740 | and what the statement that you've constructed

00:22:57.640 | is actually saying.

00:22:59.460 | So it's this quality of understanding, whatever it is,

00:23:03.140 | which is not governed by rules.

00:23:05.540 | It's not a computational procedure.

00:23:07.420 | - So this idea of understanding

00:23:08.820 | is not going to be within the rules

00:23:10.700 | of the formal system.

00:23:13.420 | - Yes, you're only using those rules anyway

00:23:15.940 | because you have understood them to be rules

00:23:18.340 | which only give you truths.

00:23:20.260 | There'd be no point in it otherwise.

00:23:22.260 | I mean, people say, well, okay,

00:23:23.700 | this is one set of rules as good as any other.

00:23:28.060 | Well, it's not true.

00:23:28.900 | You have to understand what the rules mean.

00:23:31.620 | And why does that understanding of the mean

00:23:33.580 | give you something beyond the rules themselves?

00:23:36.340 | And that's what it was.

00:23:37.380 | That's what blew my mind.

00:23:38.660 | It's somehow understanding why the rules give you truths

00:23:43.660 | enables you to transcend the rules.

00:23:45.940 | - So that's where, I mean, even at that time,

00:23:48.100 | that's already where the thought entered your mind

00:23:50.940 | that the idea of understanding,

00:23:54.000 | or we can start calling it things like intelligence

00:23:56.820 | or even consciousness, is outside the rules.

00:23:59.700 | - Yes, see, I've always concentrated on understanding.

00:24:02.940 | You know, people say, people,

00:24:04.380 | somebody's pointing out things.

00:24:05.340 | Well, we know about creativity.

00:24:07.180 | That's something a machine can't do, is create.

00:24:09.140 | Well, I don't know.

00:24:09.960 | What is creativity?

00:24:11.280 | And I don't know.

00:24:12.120 | I mean, you know, somebody can put some funny things

00:24:13.880 | on a piece of paper and say that's creative,

00:24:15.660 | and you could make a machine do that.

00:24:16.940 | Is it really creative?

00:24:18.140 | I don't know.

00:24:18.980 | You see, I worry about that one.

00:24:20.580 | I sort of agree with it in a sense,

00:24:22.900 | but it's so hard to do anything with that statement.

00:24:25.500 | But understanding, yes, you can.

00:24:27.780 | You can make, go see that understanding, whatever it is,

00:24:32.620 | and it's very hard to put your finger on it.

00:24:34.340 | That's absolutely true.

00:24:35.780 | - Can you try to define or maybe dance around

00:24:39.660 | a definition of understanding?

00:24:42.020 | - To some degree, but I don't,

00:24:44.140 | I'm often wondered about this,

00:24:46.000 | but there is something there which is very slippery.

00:24:48.960 | It's something like standing back,

00:24:52.700 | and it's got to be something, you see,

00:24:54.160 | it's also got to be something which was of value

00:24:56.940 | to our remote ancestors.

00:24:58.900 | - Right. - Because sometimes,

00:25:00.620 | there's a cartoon which I drew sometimes

00:25:03.100 | showing you how all these,

00:25:04.940 | there's in the foreground, you see this mathematician

00:25:07.140 | just doing some mathematical theorem.

00:25:08.860 | There's a little bit of a joke in that theorem,

00:25:10.500 | but let's not go into that.

00:25:12.300 | He's trying to prove some theorem,

00:25:14.420 | and he's about to be eaten by a saber-toothed tiger

00:25:17.780 | who's hiding in the undergrowth, you see.

00:25:21.100 | And in the distance, you see his cousins

00:25:24.320 | building, growing crops, building shelters,

00:25:29.080 | domesticating animals, and in the slight foreground,

00:25:31.920 | you see they built a mammoth trap,

00:25:33.280 | and this poor old mammoth is falling into a pit, you see,

00:25:36.620 | and all these people around him are about to grab him,

00:25:39.520 | you see, and well, you see, those are the ones who,

00:25:43.200 | the quality of understanding which goes with all,

00:25:47.280 | it's not just the mathematician doing his mathematics.

00:25:50.760 | This understanding quality is something else

00:25:53.660 | which has been a tremendous advantage to us,

00:25:58.140 | not just to us.

00:25:59.700 | See, I don't think consciousness is limited to humans.

00:26:03.700 | - Yeah, that's the interesting question,

00:26:04.900 | at which point, if it is indeed connected

00:26:07.400 | to the evolutionary process,

00:26:09.160 | at which point did we pick up this--

00:26:11.460 | - A very hard question.

00:26:12.660 | It's certainly, I don't think it's primates.

00:26:15.940 | You see these pictures of African hunting dogs

00:26:20.400 | and how they can plan amongst themselves

00:26:22.800 | how to catch the antelopes.

00:26:24.380 | Some of these David Attenborough films,

00:26:27.540 | I think this probably was one of them,

00:26:29.180 | and you can see the hunting dogs,

00:26:31.740 | and they divide themselves into two groups,

00:26:34.300 | and they go in two routes, two different routes.

00:26:36.820 | One of them goes and they sort of hide next to the river,

00:26:39.660 | and the other group goes around

00:26:42.420 | and they start yelping at these.

00:26:45.840 | They don't bark, I guess, whatever noise hunting dogs do,

00:26:48.960 | the antelopes, and they sort of round them up

00:26:51.020 | and they chase them in the direction of the river.

00:26:54.580 | And they're the other ones just waiting for them,

00:26:56.580 | just to get, because when they get to the river,

00:26:58.900 | it slows them down, and so they pounce on them.

00:27:02.060 | So they've obviously planned this all out somehow.

00:27:05.460 | I have no idea how.

00:27:06.760 | And there is some element of conscious planning,

00:27:11.460 | as far as I can see.

00:27:12.280 | I don't think it's just some kind of,

00:27:14.280 | so much of AI these days is done,

00:27:18.500 | what do they call it, bottom-up systems, is it?

00:27:21.040 | Yeah, where you have neural networks

00:27:23.640 | and you give them a zillion different things to look at,

00:27:27.420 | and then they sort of can choose one thing over another,

00:27:32.420 | just because it's seen so many examples

00:27:35.400 | and picks up on little signals,

00:27:38.320 | which one may not even be conscious of.

00:27:41.520 | - And that doesn't feel like understanding.

00:27:43.080 | - There's no understanding in that whatsoever.

00:27:46.080 | - Well, you're being a little bit human-centric,

00:27:48.400 | so I think I would expect--

00:27:50.580 | - Well, I'm talking about,

00:27:51.420 | I'm not with the dogs, am I?

00:27:52.600 | 'Cause the dogs-- - No, you're not.

00:27:53.440 | Sorry, not human-centric, but I misspoke.

00:27:56.680 | Biology-centric.

00:27:59.300 | Is it possible that consciousness

00:28:00.920 | would just look slightly different?

00:28:03.160 | - Well, I'm not saying it's biological,

00:28:04.680 | 'cause we don't know.

00:28:06.120 | - Right.

00:28:06.960 | - I think other examples,

00:28:07.800 | the elephants is a wonderful example, too.

00:28:09.880 | I think this was an Attenborough one,

00:28:13.940 | where the elephants have to go from,

00:28:16.040 | the troop of them have to go long distances.

00:28:20.080 | And the leader of a troop is a female,

00:28:21.600 | they all are, apparently.

00:28:23.440 | And this female, she had to go all the way

00:28:26.760 | from one part of the country to another.

00:28:30.040 | And at a certain point, she made a detour.

00:28:32.440 | And they went off in this big detour.

00:28:35.000 | All the troop came with her.

00:28:37.080 | And this was where her sister had died.

00:28:39.560 | And there were her bones lying around,

00:28:41.520 | and they go and pick up the bones,

00:28:42.840 | and they hand it around, and they caress the bones.

00:28:45.760 | And then they put them back, and they go back again.

00:28:48.560 | What in the hell are they doing?

00:28:49.920 | (laughs)

00:28:51.320 | - That's so interesting.

00:28:52.240 | - I mean, there's something going on.

00:28:54.520 | There's no clear connection with natural selection.

00:28:58.500 | There's just some deep feeling going on there,

00:29:03.080 | which has to do with their conscious experience.

00:29:05.680 | And I think it's something that overall is advantageous.

00:29:13.640 | By natural selection, but not directly

00:29:16.000 | to do with natural selection.

00:29:17.440 | - I like that, there's something going on there.

00:29:22.560 | Like I told you, I'm Russian, so I tend to romanticize

00:29:25.840 | all things of this nature.

00:29:28.200 | That it's not merely cold, hard computation.

00:29:33.200 | - Perhaps I could just slightly answer your question.

00:29:35.680 | You were asking me, what is it?

00:29:38.640 | There's something about sort of standing back

00:29:41.840 | and thinking about your own thought processes.

00:29:44.800 | I mean, there is something like that in the Godel thing.

00:29:47.760 | 'Cause you're not following the rules,

00:29:50.280 | you're standing back and thinking about the rules.

00:29:53.480 | And so there is something that you might say,

00:29:56.940 | you think about you're doing something,

00:29:58.200 | and you think, what the hell am I doing?

00:30:00.160 | And you sort of stand back and think about what it is

00:30:02.760 | that's making you think in such a way.

00:30:05.440 | - Take a step back outside the game you've been playing.

00:30:08.520 | - Yeah, you back up, and you think about,

00:30:10.680 | you're just not playing the game anymore.

00:30:12.600 | You're thinking about what the hell you're doing

00:30:14.680 | in playing this game.

00:30:16.080 | - And that's somehow, it's not a very precise description,

00:30:20.560 | but somehow it feels very true

00:30:22.320 | that that's somehow understanding.

00:30:24.400 | So this kind of reflection.

00:30:26.440 | - A reflection, yes.

00:30:27.720 | Yeah, it's a bit hard to put your finger on,

00:30:30.560 | but there is something there which I think maybe

00:30:32.960 | could be unearthed at some point,

00:30:34.400 | and see this is really what's going on.

00:30:36.840 | Why conscious beings have this advantage.

00:30:40.080 | What it is that gives them an advantage.

00:30:42.720 | And I think it goes way back.

00:30:44.200 | I don't think, we're talking about the hunting dogs

00:30:46.760 | and the elephants.

00:30:47.660 | That's pretty clear that octopuses

00:30:50.440 | have the same sort of quality.

00:30:53.320 | And we call it consciousness?

00:30:54.400 | Yeah, I think so.

00:30:55.680 | Seen enough examples of the way that they behave,

00:30:58.760 | and the evolution route is completely different.

00:31:02.520 | Does it go way back to some common ancestor,

00:31:05.880 | or did it come separately?

00:31:07.600 | - My hope is it's something simple,

00:31:09.360 | but the hard question if there's a hardware prerequisite.

00:31:13.440 | We have to develop some kind of hardware mechanisms

00:31:17.800 | in our computers.

00:31:19.160 | Like basically, as you suggest,

00:31:21.120 | and we'll get to in a second,

00:31:22.560 | we kind of have to throw away the computer

00:31:24.440 | as we know it today.

00:31:26.080 | The deterministic machines we know today

00:31:28.320 | to try to create it.

00:31:29.720 | I mean, my hope of course is not, but.

00:31:33.180 | - Well, I should go really back to the story,

00:31:37.720 | which in a sense I haven't finished.

00:31:39.880 | Because I went to these three courses, you see,

00:31:41.800 | when I was a graduate student.

00:31:43.920 | And so I started to think, well I'm really,

00:31:46.960 | I'm a pretty, what you might call a materialist

00:31:49.640 | in the sense of thinking that there's no kind of mystical

00:31:53.640 | or something or other which comes in from who knows where.

00:31:56.000 | - You still that?

00:31:56.840 | Are you still throughout your life been a materialist?

00:31:58.600 | - I don't like the word materialist

00:32:00.080 | because it suggests we know what material is.

00:32:02.840 | And that is a bad word because--

00:32:06.120 | - But there's no mystical.

00:32:07.640 | - It's not some mystical something

00:32:09.200 | which is not treatable by science.

00:32:11.800 | - That's so beautifully put,

00:32:12.720 | just to pause on that for a second.

00:32:14.320 | You're a materialist but you acknowledge

00:32:17.040 | that we don't really know what the material is.

00:32:19.160 | - That's right.

00:32:20.000 | I mean, I like to call myself a scientist I suppose.

00:32:24.280 | But it means that, yes, well you see,

00:32:28.360 | the question goes on here.

00:32:29.640 | So I began thinking, okay, if consciousness

00:32:33.200 | or understanding is something

00:32:35.920 | which is not a computational process, what can it be?

00:32:40.040 | And I knew enough from my undergraduate work,

00:32:42.280 | I knew about Newtonian mechanics

00:32:44.480 | and I knew how basically you could put it on a computer.

00:32:48.840 | There is a fundamental issue which is it important or not

00:32:53.200 | that computation depends upon discrete things,

00:32:59.160 | so using discrete elements,

00:33:02.280 | whereas the physical laws depend on the continuum.

00:33:06.240 | Now is this something to do with it?

00:33:09.640 | Is it the fact that we use the continuum in our physics

00:33:12.800 | and if we model our physical system,

00:33:15.240 | we use discrete systems like ordinary computers?

00:33:17.920 | I came to the view that that's probably not it.

00:33:22.080 | I might have to retract on that someday,

00:33:24.840 | but the view was no, you can get close enough.

00:33:28.360 | It's not altogether clear, I have to say,

00:33:30.880 | but you can get close enough.

00:33:32.960 | And I went to this course by Bondy on general relativity

00:33:37.000 | and I thought, well, you can put that on a computer.

00:33:39.480 | Of course, that was a long time before people,

00:33:42.800 | and I've sort of grown up with this,

00:33:44.000 | how people have done better and better calculations

00:33:46.200 | and they could work out black holes

00:33:48.280 | and they can then work out how black holes

00:33:50.400 | can interact with each other,

00:33:51.920 | spiral around and what kind of gravitational waves can add.

00:33:55.040 | And it's a very impressive piece of computational work,

00:33:58.640 | how you can actually work out the shapes of those signals.

00:34:01.920 | Now we have LIGO seeing these signals

00:34:04.040 | and they say, yeah, there's a black hole

00:34:05.640 | spiraling into each other.

00:34:07.400 | This is just a vindication of the power of computation

00:34:11.760 | in describing Einstein's general relativity.

00:34:16.080 | - So in that case, we can get close.

00:34:17.980 | With computation, we can get close

00:34:22.120 | to our understanding of the physics.

00:34:23.400 | - You can get very, very close.

00:34:24.640 | Now, is that close enough, you see?

00:34:26.960 | And then I went to this course by Dirac.

00:34:29.680 | Now you see, I think it was the very first lecture

00:34:32.560 | that he gave and he was talking

00:34:35.120 | about the superposition principle.

00:34:37.520 | And he said, if you have a particle,

00:34:39.920 | you usually think of particle can be over here or over there,

00:34:43.040 | but in quantum mechanics, it can be over here

00:34:45.240 | and over there at the same time.

00:34:48.080 | And you have these states which involve a superposition

00:34:51.480 | in some sense of it different locations for that particle.

00:34:56.680 | And then he got out his piece of chalk.

00:34:58.560 | Some people say he broke it in two

00:35:00.000 | as a kind of illustration of how the piece of chalk

00:35:03.000 | might be over here and over there at the same time.

00:35:05.800 | And he was talking about this and my mind wandered.

00:35:10.880 | I don't remember what he said.

00:35:13.320 | All I can remember, he's just moved on to the next topic

00:35:16.480 | and something about energy he'd mentioned,

00:35:18.560 | which I had no idea what had to do with anything.

00:35:21.000 | And so I'd been struck with this

00:35:22.880 | and worried about it ever since.

00:35:25.240 | It's probably just as well I didn't hear his explanation

00:35:27.760 | because it was probably one of these things

00:35:29.360 | to calm me down and not worry about it anymore.

00:35:32.080 | Whereas in my case, I've worried about it ever since.

00:35:35.880 | So I thought maybe that's the catch.

00:35:38.440 | There is something in quantum mechanics

00:35:41.200 | where the superpositions become one or the other.

00:35:45.040 | And that's not part of quantum mechanics.

00:35:47.800 | There's something missing in the theory.

00:35:50.020 | The theory is incomplete.

00:35:51.600 | It's not just incomplete.

00:35:52.560 | It's in a certain sense, not quite right

00:35:54.920 | because if you follow the equation,

00:35:57.480 | the basic equation of quantum mechanics,

00:35:59.320 | that's the Schrodinger equation,

00:36:01.200 | you could put that on a computer too.

00:36:02.680 | There are lots of difficulties about how many parameters

00:36:04.800 | you have to put in and so on.

00:36:06.160 | That can be very tricky,

00:36:07.480 | but nevertheless, it is a computational process.

00:36:10.880 | Modulo this question about the continuum as before,

00:36:14.960 | but it's not clear that makes any difference.

00:36:16.920 | - So our theories of quantum mechanics

00:36:18.920 | may be missing the same element

00:36:20.960 | that the universal Turing machine is missing

00:36:24.340 | about consciousness.

00:36:25.480 | - Yes, yes.

00:36:26.400 | Yeah, this is the view I held is that you need a theory

00:36:29.680 | and that that, what people call the reduction of the state

00:36:33.560 | or the collapse of the wave function,

00:36:35.760 | which you have to have,

00:36:36.760 | otherwise quantum mechanics doesn't relate

00:36:38.500 | to the world we see.

00:36:39.920 | To make it relate to the world we see,

00:36:41.440 | you've got to break the Schrodinger equation.

00:36:45.160 | Schrodinger himself was absolutely appalled by this idea,

00:36:49.240 | his own equation.

00:36:50.880 | I mean, that's why he introduced this famous Schrodinger's cat

00:36:54.580 | as a thought experiment.

00:36:56.340 | He's really saying, look,

00:36:57.180 | this is where my equation leads you into it.

00:36:59.620 | There's something wrong, something we haven't understood,

00:37:02.660 | which is basically fundamental.

00:37:05.300 | And so I was trying to put all these things together

00:37:07.880 | and said, well, it's got to be the non-computability

00:37:10.580 | comes in there.

00:37:11.900 | And I also can't quite remember when I thought this,

00:37:14.820 | but it's when gravity is involved in quantum mechanics.

00:37:18.140 | It's the combination of those two.

00:37:19.860 | And it's that point when you have good reasons to believe,

00:37:24.860 | this came much later,

00:37:27.620 | but I have good reason to believe

00:37:29.900 | that the principles of general relativity

00:37:32.900 | and those of quantum mechanics,

00:37:34.220 | most particularly it's the basic principle of equivalence,

00:37:39.220 | which goes back to Galileo.

00:37:41.380 | If you fall freely, you eliminate the gravitational field.

00:37:46.460 | So you imagine Galileo dropping his big rock

00:37:50.740 | and his little rock from the leaning tower,

00:37:52.620 | whether he actually ever did that or not,

00:37:54.140 | it's pretty irrelevant.

00:37:55.740 | And as the rocks fall to the ground,

00:37:57.780 | you have a little insect sitting on one of them

00:37:59.820 | looking at the other one.

00:38:01.380 | And it seems to think, oh, there's no gravity here.

00:38:04.220 | Of course it hits the ground

00:38:05.340 | and then you realize something's different is going on.

00:38:07.900 | But when it's in free fall, the gravity is being eliminated.

00:38:11.980 | Galileo understood that very beautifully.

00:38:15.420 | He gives these wonderful examples of fireworks

00:38:18.540 | and you see the fireworks and explode

00:38:20.380 | and you see this sphere of sparkling fireworks.

00:38:23.460 | It remains a sphere as it falls down,

00:38:26.820 | as though there were no gravity.

00:38:29.220 | So he understood that principle,

00:38:31.260 | but he couldn't make a theory out of it.

00:38:33.540 | Einstein came along, used exactly the same principle.

00:38:36.740 | And that's the basis

00:38:38.020 | of Einstein's general theory of relativity.

00:38:40.420 | Now, there is a conflict.

00:38:43.540 | This is something I did much, much later.

00:38:45.220 | So this wasn't those days, much, much later.

00:38:48.900 | You can see there is a basic conflict

00:38:51.420 | between the principle of superposition,

00:38:54.340 | the thing that Dirac was talking about,

00:38:56.340 | and the principle of general covariance.

00:38:58.700 | Well, principle of equivalence.

00:39:01.020 | Gravitational field is equivalent to an acceleration.

00:39:03.700 | - Can you pause for a second?

00:39:04.700 | What is the principle of equivalence?

00:39:06.860 | - It's this Galileo principle

00:39:08.260 | that you can eliminate, at least locally.

00:39:11.560 | You have to be in a small neighborhood

00:39:13.540 | because if you have people dropping rocks

00:39:16.420 | all around the world somewhere,

00:39:18.060 | you can't get rid of it all at once.

00:39:19.900 | But in the local neighborhood,

00:39:22.060 | you can eliminate the gravitational field

00:39:24.220 | by falling freely with it.

00:39:26.740 | And we now see that with astronauts,

00:39:28.460 | and they don't, you know, the Earth is right there.

00:39:30.660 | You can see the great globe of the Earth

00:39:32.500 | right beneath them, but they don't care about it.

00:39:35.020 | They, as far as they're concerned, there's no gravity.

00:39:37.780 | They fall freely in the gravitational field,

00:39:42.060 | and that gets rid of the gravitational field.

00:39:45.060 | And that's the principle of equivalence.

00:39:46.660 | - So what's the contradiction?

00:39:48.900 | What's the tension with superposition?

00:39:50.460 | - Ah, well, that's technical. (laughs)

00:39:52.580 | - Well, so we, just to backtrack for a second,

00:39:55.100 | just to see if we can weave a thread through it all.

00:39:57.980 | So we started to think about consciousness

00:40:02.340 | as potentially needing some of the same,

00:40:06.760 | not mystical, but some of the same magic.

00:40:08.740 | - You see, it is a complicated story.

00:40:10.620 | So, you know, people think, oh, I'm drifting away

00:40:12.660 | from the point or something.

00:40:14.220 | But I think it is a complicated story.

00:40:16.740 | So what I'm trying to say, I mean,

00:40:18.180 | I tried to put it in a nutshell, but it's not so easy.

00:40:20.740 | I'm trying to say that whatever consciousness is,

00:40:24.940 | it's not a computation.

00:40:26.780 | - Yes.

00:40:27.620 | - Or it's not a physical process

00:40:29.300 | which can be described by computation.

00:40:33.380 | - But it nevertheless could be,

00:40:34.900 | so one of the interesting models that you've proposed

00:40:39.900 | is the orchestrated objective reduction, which is--

00:40:42.020 | - Yeah, well, you see, that's going from there, you see.

00:40:44.700 | So I say I have no idea.

00:40:46.780 | So I wrote this book through my scientific career.

00:40:50.360 | I thought, you know, when I'm retired,

00:40:52.700 | I'll have enough time to write a sort of a popularish book,

00:40:55.800 | which I will explain my ideas and puzzles,

00:41:01.200 | what I like, beautiful things about physics and mathematics,

00:41:04.180 | and this puzzle about computability

00:41:07.500 | and consciousness and so on.

00:41:09.580 | And in the process of writing this book,

00:41:13.100 | well, I thought I'd do it when I was retired.

00:41:14.460 | I didn't, actually.

00:41:15.300 | I didn't wait that long because there was a radio discussion

00:41:19.420 | between Edward Fredkin and Marvin Minsky,

00:41:24.180 | and they were talking about what computers could do,

00:41:28.220 | and they were entering a big room.

00:41:30.660 | They imagined entering this big room,

00:41:32.020 | where at the other end of the room,

00:41:33.820 | two computers were talking to each other.

00:41:36.900 | And as you walk up to the computers,

00:41:39.260 | they will have communicated to each other

00:41:41.740 | more ideas, concepts, things,

00:41:45.100 | than the entire human race had ever done.

00:41:48.140 | So I thought, well, I know where you're coming from,

00:41:51.620 | but I just don't believe you.

00:41:53.620 | There's something missing.

00:41:54.920 | So I thought, well, I should write my book.

00:41:59.220 | And so I did.

00:42:01.620 | It was at roughly the same time Stephen Hawking

00:42:04.060 | was writing his "Brief History of Time."

00:42:09.060 | - '80s at some point.

00:42:11.300 | The book you're talking about is "The Emperor's New Mind."

00:42:12.900 | - "The Emperor's New Mind," that's right.

00:42:14.100 | - And both are incredible books,

00:42:16.140 | "The Brief History of Time" and "The Emperor's New Mind."

00:42:18.580 | - Yes, it was quite interesting,

00:42:19.980 | 'cause he told me he'd got Carl Sagan, I think,

00:42:23.540 | to write a forward.

00:42:25.060 | - It's a good get.

00:42:25.900 | - To the book, you see.

00:42:26.740 | So I thought, gosh, what am I gonna do?

00:42:28.300 | I'm not gonna get anywhere unless I get somebody.

00:42:31.180 | So I said, well, I know Martin Gardner,

00:42:32.780 | so I wonder if he'd do it.

00:42:34.500 | So he did, and he did a very nice forward.

00:42:36.740 | - So that's an incredible book,

00:42:38.340 | and some of the same people you mentioned,

00:42:40.460 | Ed Franken, which I guess of expert systems fame,

00:42:44.660 | and Minsky, of course, people know in the AI world,

00:42:47.020 | but they represent the artificial intelligence world.

00:42:48.980 | - Absolutely, that's right.

00:42:49.820 | - That do hope and dream that AI's intelligence is--

00:42:53.340 | - That's right.

00:42:54.180 | Well, you see, it was my thinking,

00:42:55.000 | well, you know, I see where they're coming from,

00:42:57.060 | and from that perspective--

00:42:57.900 | - I disagree.

00:42:58.740 | - Yeah, you're right, but that's not my perspective.

00:43:01.660 | So I thought I had to say it.

00:43:03.460 | And as I was writing my book, you see,

00:43:05.100 | I thought, well, I don't really know anything

00:43:06.740 | about neurophysiology, what am I doing writing this book?

00:43:09.220 | So I started reading up about neurophysiology,

00:43:12.140 | and I read up, and I think, I'm trying to find out

00:43:13.980 | how it is that nerve signals could possibly

00:43:16.460 | preserve quantum coherence.

00:43:18.380 | And all I read is that the electrical signals

00:43:20.940 | which go along the nerves create effects through the brain,

00:43:25.580 | there's no chance you can isolate it.

00:43:28.260 | So this is hopeless.

00:43:29.900 | So I come to the end of the book,

00:43:31.700 | and I more or less give up.

00:43:33.620 | I just think of something which I didn't believe in,

00:43:36.220 | as maybe this is the way around it, but no.

00:43:38.460 | And then you see, I thought, well, maybe this book

00:43:41.620 | will at least stimulate young people

00:43:43.420 | to do science or something, and I got all these letters

00:43:46.340 | from old, retired people instead.

00:43:48.460 | These are the only people who had time to read my book.

00:43:51.220 | - So, I mean--

00:43:53.180 | - Except for Stuart Hameroff.

00:43:54.980 | - Except for Stuart Hameroff.

00:43:56.460 | - Stuart Hameroff wrote to me, and he said,

00:43:58.500 | I think you're missing something.

00:44:00.140 | You don't know about microtubules, do you?

00:44:03.420 | He didn't put it quite like that,

00:44:04.860 | but that was more or less it.

00:44:05.980 | And he said, this is what you really need to consider.

00:44:08.900 | So I thought, my God, yes,

00:44:10.660 | that's a much more promising structure.

00:44:12.980 | - So, I mean, fundamentally, you were searching

00:44:16.380 | for the source of, non-computable source of consciousness

00:44:21.380 | within the human brain, in the biology.

00:44:25.100 | And so, what are, if I may ask, what are microtubules?

00:44:30.100 | - Well, you see, I was ignorant in what I'd read.

00:44:33.940 | I never came across them in the books I looked at.

00:44:37.740 | Perhaps I only read rather superficially, which is true.

00:44:40.900 | But I didn't know about microtubules.

00:44:43.140 | Stuart, I think one of the things

00:44:45.300 | that impressed him about them is

00:44:47.100 | when you see pictures of mitosis,

00:44:48.900 | that's a cell dividing, and you see all the chromosomes,

00:44:53.340 | and the chromosomes, they all get lined up,

00:44:55.740 | and then they get pulled apart.

00:44:58.020 | And so, as the cell divides, half the chromosomes go,

00:45:01.660 | you know, they divide into the two parts,

00:45:04.980 | and they go two different ways.

00:45:07.460 | And what is it that's pulling them apart?

00:45:09.860 | Well, those are these little things called microtubules.

00:45:12.940 | And so he started to get interested in them.

00:45:15.620 | And he formed the view, well, he was,

00:45:18.940 | his day job or night job, or whatever you call it,

00:45:21.140 | is to put people to sleep,

00:45:23.100 | except he doesn't like calling it sleep

00:45:24.740 | because it's different,

00:45:25.860 | general anesthetics, in a reversible way.

00:45:29.340 | So you want to make sure that they don't experience the pain

00:45:33.020 | that would otherwise be something that they feel.

00:45:36.820 | And consciousness is turned off for a while,

00:45:40.380 | and it can be turned back on again.

00:45:41.940 | So it's crucial that you can turn it off and turn it on.

00:45:44.980 | And what do you do when you're doing that?

00:45:47.500 | What do general anesthetic gases do?

00:45:49.740 | And see, he formed the view

00:45:53.340 | that it's the microtubules that they affect.

00:45:56.940 | And the details of why he formed that view

00:46:00.020 | is not all that clear to me,

00:46:02.380 | but there's an interesting story he keeps talking about.

00:46:05.700 | But I found this very exciting

00:46:08.540 | because I thought these structures,

00:46:11.540 | these little tubes which inhabit pretty well all cells,

00:46:15.460 | it's not just neurons,

00:46:16.820 | apart from red blood cells,

00:46:20.620 | they inhabit pretty well all the other cells in the body.

00:46:23.980 | But they're not all the same kind.

00:46:25.420 | You get different kinds of microtubules.

00:46:28.060 | And the ones that excited me the most,

00:46:31.780 | this may still not be totally clear,

00:46:34.540 | but the ones that excited me most

00:46:36.220 | were the only ones that I knew about at the time,

00:46:39.340 | because they're very, very symmetrical structures.

00:46:43.300 | And I had reason to believe

00:46:45.660 | that these very symmetrical structures

00:46:48.140 | would be much better at preserving a quantum state,

00:46:52.180 | quantum coherence,

00:46:53.140 | preserving the thing without,

00:46:54.780 | you just need to preserve certain degrees of freedom

00:46:58.840 | without them leaking into the environment.

00:47:01.140 | Once they leak into the environment, you're lost.

00:47:03.460 | So you've got to preserve these quantum states at a level

00:47:08.180 | which the state reduction process comes in,

00:47:12.460 | and that's where I think the non-computability comes in.

00:47:16.280 | And it's the measurement process in quantum mechanics,

00:47:19.740 | what's going on.

00:47:20.900 | - So something about the measurement process

00:47:23.660 | and what's going on,

00:47:24.500 | something about the structure of the microtubules,

00:47:27.220 | your intuition says, maybe there's something here.

00:47:29.620 | Maybe this kind of structure allows

00:47:32.580 | for the mystery of the quantum mechanics.

00:47:35.580 | - There was a much better chance, yes.

00:47:37.340 | It just struck me that partly it was the symmetry,

00:47:40.860 | because there is a feature of symmetry.

00:47:43.260 | You can preserve quantum coherence

00:47:46.380 | much better with symmetrical structures.

00:47:48.260 | And so there's a good reason for that.

00:47:50.420 | And that impressed me a lot.

00:47:52.620 | I didn't know the difference between the A-lattice

00:47:54.780 | and B-lattice at that time, which could be important.

00:47:58.020 | No, that couldn't, which isn't talked about much.

00:48:00.940 | - But that's in some sense details.

00:48:02.700 | We've got to take a step back just to say,

00:48:04.420 | in case people are not familiar.

00:48:06.220 | So this was called the orchestrated objective reduction idea

00:48:11.220 | or ORC-OR, which is a biological philosophy of mind

00:48:18.460 | that postulates that consciousness originates

00:48:20.700 | at the quantum level inside neurons.

00:48:22.340 | So that has to do with your search for where,

00:48:25.300 | where is it coming from?

00:48:26.660 | So that's counter to the notion that consciousness

00:48:29.540 | might arise from the computation performed by the synapses.

00:48:33.180 | - Yes, I think the key point,

00:48:35.540 | sometimes people say it's because it's quantum mechanical.

00:48:40.540 | It's not just that.

00:48:42.620 | See, it's more outrageous than that.

00:48:45.040 | You see, this is one reason I think we're so far off from it

00:48:48.300 | because we don't even know the physics right.

00:48:51.020 | You see, it's not just quantum mechanics.

00:48:53.820 | People say, oh, you know,

00:48:54.900 | quantum systems and biological structures.

00:48:57.300 | No, well, you're starting to see

00:48:59.100 | that some basic biological systems does depend on quantum.

00:49:04.100 | I mean, look, in the first place,

00:49:07.540 | all of chemistry is quantum mechanics.

00:49:09.780 | People got used to that, so they don't count that.

00:49:13.100 | So he said, let's not count quantum chemistry.

00:49:16.620 | We sort of got the hang of that, I think.

00:49:19.100 | But you have quantum effects,

00:49:21.340 | which are not just chemical, in photosynthesis.

00:49:25.420 | And this is one of the striking things

00:49:27.220 | in the last several years,

00:49:29.300 | that photosynthesis seems to be a basically quantum process,

00:49:34.220 | which is not simply chemical.

00:49:36.860 | It's using quantum mechanics in a very basic way.

00:49:41.460 | So you could start saying, oh, well,

00:49:43.100 | with photosynthesis is based on quantum mechanics,

00:49:45.580 | why not behavior of neurons and things like that?

00:49:50.260 | Maybe there's something which is a bit like photosynthesis

00:49:53.740 | in that respect.

00:49:55.060 | But what I'm saying is even more outrageous than that,

00:49:58.140 | because those things are talking

00:50:00.780 | about conventional quantum mechanics.

00:50:03.700 | Now, my argument says that conventional quantum mechanics,

00:50:07.540 | if you're just following the Schrodinger equation,

00:50:09.420 | that's still computable.

00:50:11.700 | So you've got to go beyond that.

00:50:13.900 | So you've got to go to where quantum mechanics goes wrong

00:50:18.900 | in a certain sense.

00:50:21.060 | You have to be a little bit careful about that,

00:50:23.780 | because the way people do quantum mechanics

00:50:26.020 | is a sort of mixture of two different processes.

00:50:31.020 | One of them is the Schrodinger equation,

00:50:35.460 | which is an equation that Schrodinger wrote down,

00:50:38.820 | and it tells you how the state of a system evolves.

00:50:42.620 | And it evolves, according to this equation,

00:50:44.780 | completely deterministic,

00:50:47.340 | but it evolves into ridiculous situations.

00:50:50.340 | And this was what Schrodinger was very much pointing out

00:50:52.700 | with his cat.

00:50:54.260 | He says, you follow my equation,

00:50:55.860 | that's Schrodinger's equation,

00:50:57.380 | and you could say that you have to,

00:51:00.220 | you have a cat which is dead and alive at the same time.

00:51:04.300 | That would be the evolution of the Schrodinger equation

00:51:07.180 | would lead to a state,

00:51:08.740 | which is the cat being dead and alive at the same time.

00:51:12.740 | And he's more or less saying, this is an absurdity.

00:51:15.700 | People nowadays say, oh, well, Schrodinger said

00:51:18.420 | you can have a cat which is dead and alive.

00:51:19.780 | It's not that, you see, he was saying, this is an absurdity.

00:51:23.420 | There's something missing.

00:51:24.740 | And that the reduction of the state

00:51:28.660 | or the collapse of the wave function or whatever it is,

00:51:31.980 | is something which has to be understood.

00:51:34.740 | It's not following the Schrodinger equation.

00:51:37.820 | It's not the way we conventionally do quantum mechanics.

00:51:41.940 | There's something more than that.

00:51:43.620 | And it's easy to quote authority here because Einstein,

00:51:48.220 | at least three of the greatest physicists of 20th century,

00:51:54.740 | who were very fundamental in developing quantum mechanics,

00:51:58.780 | Einstein, one of them, Schrodinger, another, Dirac, another.

00:52:03.620 | You have to look carefully at Dirac's writing

00:52:05.500 | 'cause he didn't tend to say this out loud very much

00:52:09.180 | 'cause he was very cautious about what he said.

00:52:11.300 | You find the right place and you see,

00:52:13.460 | he says quantum mechanics is a provisional theory.

00:52:16.620 | We need something which explains

00:52:21.660 | the collapse of a wave function.

00:52:23.500 | We need to go beyond the theory we have now.

00:52:26.220 | I happen to be one of the kinds of people,

00:52:29.900 | there are many, there is a whole group of people,

00:52:31.860 | they're all considered to be a bit mavericks,

00:52:35.580 | who believe that quantum mechanics needs to be modified.

00:52:38.900 | There's a small minority of those people,

00:52:41.180 | which are already a minority,

00:52:42.740 | who think that the way in which it's modified

00:52:46.220 | has to be with gravity.

00:52:47.540 | And there is an even smaller minority of those people

00:52:51.420 | who think it's the particular way that I think it is.

00:52:54.540 | So-- - So those are

00:52:55.620 | the quantum gravity folks, but what's--

00:52:57.500 | - You see, quantum gravity is already not this

00:53:00.700 | because when you say quantum gravity,

00:53:02.620 | what you really mean is quantum mechanics

00:53:05.420 | applied to gravitational theory.

00:53:07.980 | So you say, let's take this wonderful formalism

00:53:10.620 | of quantum mechanics and make gravity fit into it.

00:53:15.220 | So that is what quantum gravity is meant to be.

00:53:18.020 | Now I'm saying, you've got to be more even handed

00:53:21.460 | that gravity affects the structure

00:53:23.140 | of quantum mechanics too.

00:53:24.420 | It's not just you quantize gravity,

00:53:26.820 | you've got to gravitize quantum mechanics.

00:53:29.420 | And it's a two-way thing.

00:53:31.140 | - But then when do you even get started?

00:53:32.980 | So that you're saying that we have to figure out

00:53:35.300 | a totally new ideas in that. - Exactly.

00:53:37.960 | No, you're stuck, you don't have a theory.

00:53:41.260 | That's the trouble.

00:53:42.780 | So this is a big problem, actually,

00:53:44.740 | you say, okay, well, what's the theory?

00:53:45.940 | I don't know. (laughs)

00:53:47.260 | - So maybe in the very early days, sort of--

00:53:49.420 | - It is in the very early days,

00:53:51.020 | but just making this point. - Yes.

00:53:53.780 | - You see, Stuart Hameroff tends to be,

00:53:55.780 | oh, Penrose says that it's got to be

00:53:58.140 | a reduction of the state and so on, so let's use it.

00:54:00.580 | The trouble is Penrose doesn't say that.

00:54:02.100 | Penrose says, well, I think that.

00:54:03.900 | - Yeah, right. (laughs)

00:54:05.460 | - We have no experiments as yet, which shows that.

00:54:10.060 | There are experiments which are being thought through

00:54:12.540 | and which I'm hoping will be performed.

00:54:15.700 | There is an experiment which is being developed

00:54:18.300 | by Dirk Baumeister, who I've known for a long time,

00:54:22.020 | who shares his time between Leiden in the Netherlands

00:54:25.300 | and Santa Barbara in the US.

00:54:27.860 | And he's been working on an experiment

00:54:29.700 | which could perhaps demonstrate that quantum mechanics,

00:54:34.700 | as we now understand it,

00:54:36.620 | if you don't bring in the gravitational effects,

00:54:39.020 | has to be modified.

00:54:41.720 | - And then there's also experiments that are underway

00:54:45.980 | that kind of look at the microtubule side of things

00:54:50.620 | to see if there's, in the biology,

00:54:52.580 | you could see something like that.

00:54:53.820 | Could you briefly mention it?

00:54:55.020 | Because that's a really sort of one of the only

00:54:58.140 | experimental attempts in the very early days

00:55:00.860 | of even thinking about consciousness.

00:55:02.740 | - I think there's a very serious area here,

00:55:05.420 | which is what Stuart Hameroff is doing,

00:55:07.300 | and I think it's very important.

00:55:09.020 | One of the few places that you can really get

00:55:11.740 | a bit of a handle on what consciousness is

00:55:14.780 | is what turns it off.

00:55:17.040 | And when you're thinking about general anesthetics,

00:55:20.020 | it's very specific.

00:55:21.660 | These things turn consciousness off.

00:55:24.220 | What the hell do they do?

00:55:26.300 | Well, Stuart and a number of people who work with him

00:55:29.900 | and others happen to believe that the general anesthetics

00:55:34.420 | directly affect microtubules.

00:55:36.740 | And there is some evidence for this.

00:55:38.660 | I don't know how strong it is

00:55:40.180 | and how watertight the case is,

00:55:43.780 | but I think there is some evidence

00:55:45.380 | pointing in that kind of direction.

00:55:49.140 | It's not just an ordinary chemical process.

00:55:51.180 | There's something quite different about it.

00:55:53.500 | And one of the main candidates is that

00:55:57.420 | these anesthetic gases do affect directly microtubules.

00:56:01.640 | And how strong that evidence is,

00:56:04.460 | I wouldn't be in a position to say,

00:56:07.100 | but I think there is fairly impressive evidence.

00:56:09.860 | - And the point is the experiments are being undertaken,

00:56:12.700 | which is-- - Yes.

00:56:13.540 | I mean, that is experimental.

00:56:14.700 | You see, so it's a very clear direction

00:56:17.260 | where you can think of experiments which could indicate

00:56:20.900 | whether or not it's really microtubules,

00:56:23.100 | which the anesthetic gases directly affect.

00:56:26.100 | - That's really exciting.

00:56:27.300 | One of the sad things is, as far as I'm,

00:56:30.380 | from my outside perspective,

00:56:31.780 | is not many people are working on this.

00:56:34.420 | So there's a very, like with Stuart,

00:56:37.260 | it feels like there's very few people

00:56:38.940 | are carrying the flag forward on this.

00:56:41.260 | - I think it's not many in the sense it's a minority,

00:56:44.860 | but it's not zero anymore.

00:56:46.420 | You see, when Stuart and I were originally taught by this,

00:56:49.620 | you know, we were just us and a few of our friends,

00:56:52.860 | there weren't many people taking it,

00:56:54.220 | but it's grown into one of the main viewpoints.

00:56:59.220 | There might be about four or five or six different views

00:57:04.500 | that people hold, and it's one of them.

00:57:07.660 | So it's considered as one of the possible

00:57:11.060 | lines of thinking, yes.

00:57:13.360 | - You describe physics theories

00:57:15.100 | as falling into one of three categories,

00:57:16.940 | the superb, the useful, or the tentative.

00:57:19.860 | I like those words.

00:57:21.700 | It's a beautiful categorization.

00:57:23.580 | Do you think we'll ever have a superb theory

00:57:26.980 | of intelligence and of consciousness?

00:57:29.780 | - We might.

00:57:30.620 | We're a long way from it.

00:57:33.720 | I don't think we're even,

00:57:35.020 | whether we're in the tentative scale.

00:57:36.920 | I mean, it's--

00:57:37.860 | - You don't think we've even entered

00:57:41.260 | the realm of tentative?

00:57:42.460 | - Probably not, I think it's--

00:57:43.300 | - Yeah, that's right.

00:57:44.540 | - No, when you see this, it's so controversial.

00:57:47.140 | We don't have a clear view,

00:57:49.180 | which is accepted by a majority.

00:57:53.100 | I mean, you say, yeah, people,

00:57:54.340 | most views are computational in one form or another.

00:57:57.300 | I think it's some, but it's not very clear,

00:57:59.260 | 'cause even the IIT people who think of them

00:58:04.260 | as computational, but I've heard them say,

00:58:07.900 | "No, consciousness is supposed to be not computational."

00:58:09.980 | I say, "Well, if it's not computational,

00:58:10.940 | "what in the hell is it?

00:58:12.060 | "What's going on?

00:58:14.060 | "What physical processes are going on which are that?"

00:58:18.900 | - What does it mean for something to be computational, then?

00:58:21.700 | So, is--

00:58:23.780 | - Well, there has to be a process which is,

00:58:27.560 | you see, it's very curious the way the history

00:58:31.820 | has developed in quantum mechanics,

00:58:34.140 | because very early on, people thought

00:58:36.060 | there was something to do with consciousness,

00:58:37.780 | but it was almost the other way around.

00:58:39.980 | You see, you have to say the Schrodinger equations

00:58:42.980 | says all these different alternatives happen all at once,

00:58:46.020 | and then when is it that only one of them happens?

00:58:48.540 | Well, one of the views, which was quite commonly held

00:58:50.820 | by a few distinguished quantum physicists,

00:58:53.460 | that's when a conscious being looks at the system

00:58:56.620 | or becomes aware of it, and at that point,

00:58:59.300 | it becomes one or the other.

00:59:00.700 | That's a role where consciousness

00:59:03.700 | is somehow actively reducing the state.

00:59:07.020 | My view is almost the exact opposite of that.

00:59:10.100 | It's the state reduces itself in some way which,

00:59:14.140 | some non-computational way which we don't understand,

00:59:17.100 | we don't have a proper theory of,

00:59:19.180 | and that is the building block of what consciousness is.

00:59:24.180 | So consciousness, it's the other way around.

00:59:26.220 | It depends on that choice which nature makes all the time

00:59:31.220 | when the state becomes one or the other,

00:59:33.100 | rather than the superposition of one and the other,

00:59:36.020 | and when that happens, there is what we're saying now,

00:59:39.520 | an element of proto-consciousness takes place.

00:59:43.080 | Proto-consciousness is, roughly speaking,

00:59:45.580 | the building block out of which

00:59:47.360 | actual consciousness is constructed.

00:59:50.020 | So you have these proto-conscious elements

00:59:53.140 | which are when the state decides

00:59:54.980 | to do one thing or the other,

00:59:57.500 | and that's the thing which, when organized together,

01:00:01.500 | that's the OR part in OrcOR, but the Orc part,

01:00:05.380 | that's the, the OR part, at least one can see

01:00:08.540 | where we're driving as a theory.

01:00:10.220 | You can say it's the quantum choice

01:00:13.100 | of going this way or that way,

01:00:14.660 | but the Orc part, which is the orchestration of this,

01:00:17.660 | is much more mysterious,

01:00:19.540 | and how does the brain somehow orchestrate

01:00:23.200 | all these individual OR processes

01:00:26.540 | into a genuine conscious experience?

01:00:31.540 | - And it might be something that's beautifully simple,

01:00:35.060 | but we're completely in the dark about.

01:00:37.740 | - Yeah, I think at the moment, that's the thing.

01:00:40.180 | You know, we happily put the word Orc down there

01:00:42.900 | to say orchestrated, but that's even more unclear

01:00:47.460 | what that really means.

01:00:49.020 | - Just like the word material, orchestrated, who knows?

01:00:54.020 | And we've been dancing a little bit

01:00:56.180 | between the word intelligence

01:00:58.760 | or understanding and consciousness.

01:01:00.940 | Do you kind of see those as sitting

01:01:03.020 | in the same space of mystery as we've been discussing?

01:01:05.780 | - Yes, but you see, I tend to say

01:01:07.780 | you have understanding and intelligence and awareness.

01:01:13.620 | And somehow, understanding is in the middle of it.

01:01:18.620 | You see, I like to say, could you say of an entity

01:01:24.140 | that is actually intelligent

01:01:27.820 | if it doesn't have the quality of understanding?

01:01:30.340 | Maybe I'm using terms I don't even know how to define,

01:01:33.700 | but who cares?

01:01:34.540 | I'm just relating them.

01:01:35.380 | - They're somewhat poetic, so if I somehow understand them.

01:01:38.460 | - Yes, that's right, we don't, exactly.

01:01:40.860 | - But they're not mathematical in nature.

01:01:42.260 | - Yes, you see, as a mathematician,

01:01:44.060 | I don't know how to define any of them,

01:01:45.380 | but at least I can point to the connections.

01:01:47.420 | So the idea is intelligence is something

01:01:50.220 | which I believe needs understanding.

01:01:53.940 | Otherwise, you wouldn't say it's really intelligence.

01:01:56.380 | And understanding needs awareness.

01:01:59.420 | Otherwise, you wouldn't really say it's understanding.

01:02:01.980 | Do you say of an entity that understands something

01:02:04.380 | unless it's really aware of it, in our normal usage.

01:02:08.420 | So there's a three sort of awareness, understanding,

01:02:11.780 | and intelligence.

01:02:13.820 | And I just tend to concentrate on understanding

01:02:17.540 | because that's where I can say something.

01:02:19.780 | And that's the Godel theorem, things like that.

01:02:21.980 | But what does it mean to perceive the color blue

01:02:26.460 | or something, I'm foggiest.

01:02:28.500 | That's a much more difficult question.

01:02:31.060 | I mean, is it the same if I see a color blue and you see it?

01:02:34.060 | If you're something with, what, this condition,

01:02:36.580 | what is it called?

01:02:38.300 | - Oh, where you assign a sound to a color?

01:02:41.540 | - Yeah, that's right.

01:02:42.380 | You get colors and sounds mixed up.

01:02:44.740 | And that sort of thing.

01:02:45.860 | I mean, an interesting subject.

01:02:47.780 | - But from the physics perspective,

01:02:50.860 | from the fundamentals perspective, we don't.

01:02:53.220 | - I think we're way off having much understanding

01:02:56.300 | what's going on there.

01:02:57.900 | - In your 2010 book, "Cycles of Time,"

01:03:01.340 | you suggest that another universe

01:03:03.540 | may have existed before the Big Bang.

01:03:06.220 | Can you describe this idea?

01:03:08.780 | First of all, what is the Big Bang?

01:03:10.940 | Sounds like a funny word.

01:03:13.020 | And what may have been there before it?

01:03:17.060 | - Yes, just as a matter of terminology,

01:03:19.300 | I don't like to call it another universe.

01:03:21.740 | 'Cause when you have another universe,

01:03:23.020 | you think of it kind of quite separate from us.

01:03:25.500 | But these things, they're not separate.

01:03:28.660 | Now, the Big Bang, conventional theory.

01:03:31.820 | You see, I was actually brought up in the sense

01:03:34.780 | of when I started getting interested in cosmology,

01:03:36.900 | there was a thing called the steady state model,

01:03:39.260 | which was sort of philosophically very interesting.

01:03:41.380 | And there wasn't a Big Bang in that theory,

01:03:43.020 | that somehow new material was created all the time

01:03:46.980 | in the form of hydrogen,

01:03:48.100 | and the universe kept on expanding, expanding, expanding,

01:03:50.540 | and there was room for more hydrogen.

01:03:52.580 | It was a rather philosophically nice picture.

01:03:54.980 | It was disproved when the Big Bang,

01:03:59.140 | well, when I say the Big Bang,

01:04:01.860 | this was theoretically discovered

01:04:04.900 | by people trying to solve Einstein's equations

01:04:07.900 | and apply it to cosmology.

01:04:09.340 | Einstein didn't like the idea.

01:04:10.700 | He liked a universe which was there all the time.

01:04:14.340 | And he had a model which was there all the time.

01:04:16.740 | But then there was this discovery, accidental discovery,

01:04:20.740 | a very important discovery, of this microwave background.

01:04:25.140 | And if you, there's the crackle on your television screen,

01:04:28.460 | which is already sensing this microwave background,

01:04:32.740 | which is coming at us from all directions.

01:04:35.140 | And you can trace it back and back and back and back,

01:04:37.740 | and it came from a very early stage of the universe.

01:04:40.820 | Well, it's part of the Big Bang theory.

01:04:43.700 | The Big Bang theory was when people tried

01:04:45.660 | to solve Einstein's equations.

01:04:47.660 | They really found you had to have this initial state

01:04:50.780 | where the universe, it used to be called

01:04:52.420 | the primordial atom and things like this.

01:04:55.340 | There's Friedmann and Lemaitre.

01:04:57.860 | Friedmann was a Russian, Lemaitre was a Belgian.

01:05:01.420 | And they independently, well, basically Friedmann first.

01:05:04.780 | And Lemaitre talked about the initial state,

01:05:08.860 | which is a very, very concentrated initial state,

01:05:11.420 | which seemed to be the origin of the universe.

01:05:13.500 | - Primordial atom, that's a nice--

01:05:14.820 | - Primordial atom is what he called it, yes.

01:05:16.740 | - Beautiful term.

01:05:17.620 | - And then it became, well, Fred Hoyle used the term

01:05:20.220 | Big Bang in a kind of derogatory sense.

01:05:22.580 | - Just like with the Schrodinger and the cats, right?

01:05:25.100 | - Yes, it's like sort of, it got picked up on,

01:05:28.300 | whereas it wasn't his intention originally.

01:05:30.780 | But then the evidence piled up and piled up.

01:05:33.620 | And one of my friends that I learned a lot from

01:05:36.380 | and when I was in Cambridge was Dennis Schama.

01:05:38.060 | He was a great proponent of steady state.

01:05:40.580 | And then he got converted, he said, "No, I'm sorry.

01:05:43.340 | "I had a great respect for him."

01:05:44.460 | He went around lecturing, said, "I was wrong.

01:05:46.700 | "The steady state model doesn't work.

01:05:48.800 | "There was this Big Bang.

01:05:50.820 | "And this microwave background that you see,

01:05:53.520 | "okay, it's not actually quite the Big Bang."

01:05:55.340 | When I said not quite, it's about 380,000 years

01:05:58.620 | after the Big Bang, but that's what you see.

01:06:01.440 | But then you have to have had this Big Bang

01:06:03.200 | before it in order to make the equations work.

01:06:05.740 | And it works beautifully, except for one little thing,

01:06:09.660 | which is this thing called inflation,

01:06:11.060 | which people had to put into it to make it work.

01:06:14.060 | When I first heard of it, I didn't like it at all.

01:06:16.860 | - What's inflation?

01:06:17.940 | - Inflation is it in the first,

01:06:20.360 | I'm gonna give you a very tiny number.

01:06:22.720 | Think of a second, that's not very long.

01:06:25.180 | Now I'm gonna give you a fraction of a second,

01:06:26.960 | one over a number.

01:06:29.460 | This number has 32 digits.

01:06:32.900 | Between, well, let's say between 36 and 32 digits.

01:06:37.720 | Tiny, tiny time between those two tiny ridiculous seconds,

01:06:42.720 | fraction of a second, the universe was supposed

01:06:45.600 | to have expanded in this exponential way.

01:06:49.000 | An enormous way, for no apparent reason,

01:06:51.360 | you had to invent a particular thing

01:06:53.520 | called the inflaton field to make it do it.

01:06:56.040 | And I thought this is completely crazy.

01:06:58.180 | There are reasons why people stuck with this idea.

01:07:01.980 | You see, the thing is that I formed my model

01:07:04.200 | for reasons which are very fundamental, if you like.

01:07:07.680 | It has to do this very fundamental principle,

01:07:10.420 | which is known as the second law of thermodynamics.

01:07:13.800 | The second law of thermodynamics says more or less,

01:07:16.120 | things get more and more random as time goes on.

01:07:18.700 | Now, another way of saying exactly the same thing

01:07:22.080 | is things get less and less random as things go back.

01:07:25.400 | As you go back in time, they get less and less random.

01:07:28.040 | So you go back and back and back and back.

01:07:30.100 | And the earliest thing you can directly see

01:07:32.040 | is this microwave background.

01:07:33.560 | What's one of the most striking features of it

01:07:37.560 | is that it's random.

01:07:39.240 | It has this, what you call this spectrum of,

01:07:42.500 | which is what's called the Planck spectrum of frequencies,

01:07:47.800 | different intensities for different frequencies.

01:07:49.640 | And it's this wonderful curve due to Max Planck.

01:07:53.300 | And what's it telling you?

01:07:54.680 | It's telling you that the entropy is at a maximum.

01:07:58.000 | Started off at a maximum and it's going up ever since.

01:08:02.100 | I call that the mammoth in the room.

01:08:03.880 | I mean, it's a paradox.

01:08:05.560 | - A mammoth, yeah, it is.

01:08:07.280 | - And so people, why don't cosmologists worry about this?

01:08:10.480 | So I worried about it.

01:08:11.920 | And then I thought, well, it's not really a paradox

01:08:14.920 | because you're looking at matter and radiation

01:08:19.040 | at a maximum entropy state.

01:08:20.680 | What you're not seeing directly in that is the gravitation.

01:08:25.360 | It's gravitation, which is not thermalized.

01:08:28.440 | The gravitation was very, very low entropy.

01:08:32.000 | And it's low entropy by the uniformity.

01:08:34.440 | And you see that in the microwave too.

01:08:35.920 | It's very uniform over the whole sky.

01:08:38.240 | I'm compressing a long story into a very short few sentences.

01:08:40.800 | - And doing a great job, yeah.

01:08:42.000 | - So what I'm saying is that there's a huge puzzle.

01:08:45.680 | Why was gravity in this very low entropy state,

01:08:50.600 | very highly organized state, everything else was all random?

01:08:55.160 | And that, to me, was the biggest problem in cosmology.

01:08:58.960 | The biggest problem, nobody seems to even worry about it.

01:09:02.760 | People say they solved all the problems

01:09:04.440 | and they don't even worry about it.

01:09:05.520 | They think inflation solves it.

01:09:07.320 | It doesn't, it can't.

01:09:08.720 | Because it's just--

01:09:11.240 | - Just to clarify, that was your problem

01:09:14.680 | with the inflation describing some aspect

01:09:18.160 | of the moments right after the Big Bang?

01:09:20.520 | - Inflation is supposed to stretch it out

01:09:22.240 | and make it all uniform, you see.

01:09:23.960 | It doesn't do it because it can only do it

01:09:25.440 | if it's uniform already at the beginning.

01:09:27.920 | You just have to look at it.

01:09:28.760 | I can't go into the details.

01:09:30.400 | But it doesn't solve it.

01:09:31.720 | And it was completely clear to me it doesn't solve it.

01:09:33.880 | - But where does the conformal cyclic cosmology of--

01:09:36.880 | - Yeah, well--

01:09:37.720 | - Starting to talk about something before--

01:09:39.800 | - Yes.

01:09:40.640 | - That singularity--

01:09:41.480 | - Well, I began, I was just thinking to myself,

01:09:44.240 | how boring this universe is going to be.

01:09:47.680 | You've got this exponential expansion.

01:09:49.520 | This was discovered early in the,

01:09:51.520 | in this century, 21st century.

01:09:56.520 | People discovered that these supernova exploding stars

01:10:01.040 | showed that the universe is actually undergoing

01:10:04.560 | this exponential expansion.

01:10:06.600 | So it's a self-similar expansion.

01:10:09.540 | And it seems to be a feature of this term

01:10:14.280 | that Einstein introduced into his cosmology

01:10:17.120 | for the wrong reason.

01:10:18.520 | He wanted a universe that was static.

01:10:20.600 | He put this new term into his cosmology

01:10:23.480 | to make it make sense.

01:10:24.440 | It's called the cosmological constant.

01:10:26.480 | And then when he got convinced

01:10:28.280 | that the universe had a big bang,

01:10:29.560 | he retracted it,

01:10:30.880 | complaining that this was his greatest blunder.

01:10:33.280 | The trouble is it wasn't a blunder.

01:10:34.640 | It was actually right.

01:10:35.880 | (laughs)

01:10:36.720 | Very ironic.

01:10:37.880 | And so the universe seems to be behaving

01:10:40.240 | with this cosmological constant.

01:10:41.960 | Okay, so this universe is expanding and expanding.

01:10:45.080 | What's going to happen in the future?

01:10:46.320 | Well, it gets more and more boring for a while.

01:10:48.840 | What's the most interesting thing in the universe?

01:10:50.560 | Well, there's black holes.

01:10:51.840 | The black holes more or less gulp down

01:10:53.640 | entire clusters of galaxies.

01:10:56.640 | The cluster, it'll swallow up most of our galaxy.

01:10:59.080 | We will run into our Andromeda galaxy's black hole.

01:11:01.440 | That black hole will swallow our one.

01:11:03.640 | They'll get bigger and bigger,

01:11:04.680 | and they'll basically swallow up

01:11:07.080 | the whole cluster of galaxies,

01:11:09.040 | gulp it all down, pretty well all, most of it,

01:11:11.800 | maybe not all, most of it.

01:11:13.720 | Okay, and then that'll happen to,

01:11:15.280 | there'll be just these black holes around,

01:11:16.760 | pretty boring, but still not as boring

01:11:18.360 | as it's going to get.

01:11:19.560 | It's going to get more boring

01:11:20.600 | because these black holes, you wait,

01:11:22.120 | you wait, and you wait, and you wait,

01:11:23.520 | and you wait, an unbelievable length of time,

01:11:26.080 | and Hawking's black hole evaporation starts to come in.

01:11:30.240 | And the black holes, you just, it's incredibly tedious.

01:11:34.280 | Finally evaporate away.

01:11:36.280 | Each one goes away, disappears with a pop at the end.

01:11:39.640 | What could be more boring?

01:11:40.920 | It was boring then.

01:11:41.960 | Now this is really boring.

01:11:43.800 | There's nothing, not even black holes.

01:11:46.560 | Universe gets colder and colder and colder and colder.

01:11:48.880 | And I thought, this is very, very boring.

01:11:52.400 | Now that's not science, is it?

01:11:54.480 | But it's emotional.

01:11:56.360 | So I thought, who's going to be bored by this universe?

01:11:59.560 | Not us, we won't be around.

01:12:01.520 | It'll be mostly photons running around.

01:12:04.080 | And what the photons do, they don't get bored

01:12:06.160 | because it's part of relativity, you see.

01:12:08.760 | It's not really that they don't experience anything,

01:12:10.840 | that's not the point.

01:12:12.360 | Photons get right out to infinity

01:12:15.800 | without experience any time.

01:12:18.560 | It's the way relativity works.

01:12:21.000 | And this was part of what I used to do in my old days

01:12:23.480 | when I was looking at gravitational radiation

01:12:25.240 | and how things behaved to infinity.

01:12:27.480 | Infinity is just like another place.

01:12:30.040 | You can squash it down,

01:12:31.880 | as long as you don't have any mass in the world,

01:12:34.440 | infinity is just another place.

01:12:36.480 | The photons get there, the gravitons get there.

01:12:39.720 | What do they get?

01:12:40.560 | They run to infinity.

01:12:42.120 | They say, well, now I'm here, what do I?

01:12:44.320 | There's something on the other side, is there?

01:12:46.680 | In the usual view, it's just a mathematical notion.

01:12:48.640 | There's nothing on the other side,

01:12:49.640 | that's just the boundary of it.

01:12:51.720 | A nice example is this beautiful series of pictures

01:12:55.000 | by the Dutch artist, M.C. Escher.

01:12:57.200 | You may know them, the ones called Circle Limits.

01:12:59.680 | They're a very famous one with the angels and the devils.

01:13:02.480 | And you can see them crowding and crowding

01:13:04.200 | and crowding up to the edge.

01:13:06.000 | Now, the kind of geometry

01:13:07.440 | that these angels and devils inhabit,

01:13:10.160 | that's their infinity.

01:13:11.520 | But from our perspective,

01:13:14.120 | infinity is just a place.

01:13:16.840 | Okay, there is--

01:13:17.680 | - I'm sorry, can you just take a brief pause?

01:13:20.200 | - Yes.

01:13:21.040 | - In just the words you're saying,

01:13:22.840 | infinity is just a place.

01:13:24.080 | So, for the most part, infinity,

01:13:26.960 | sort of even just going back,

01:13:28.760 | infinity is a mathematical concept?

01:13:31.200 | - I think this is one of the--

01:13:32.040 | - You think there's an actual physical manifestation?

01:13:35.480 | In which way does infinity ever manifest itself

01:13:38.400 | in our physical universe?

01:13:40.120 | - Well, it does in various places.

01:13:41.760 | You see, it's a thing that,

01:13:43.400 | if you're not a mathematician,

01:13:44.480 | you think, oh, infinity,

01:13:45.320 | I can't think about that.

01:13:46.480 | Mathematicians think about infinity all the time.

01:13:48.680 | They get used to the idea,

01:13:49.880 | and they just play around

01:13:50.880 | with different kinds of infinities,

01:13:52.280 | and it becomes no problem.

01:13:54.200 | But you just have to take my word for it.

01:13:57.240 | Now, one of the things is,

01:13:58.440 | you see, you take a Euclidean geometry.

01:14:00.800 | Well, it just keeps on, keeps on, keeps on going,

01:14:02.680 | and it goes out to infinity.

01:14:04.640 | Now, there's other kinds of geometry,

01:14:06.160 | and this is what's called hyperbolic geometry.

01:14:09.240 | It's a bit like Euclidean geometry,

01:14:10.800 | it's a little bit different.

01:14:12.120 | It's like what Escher was trying to describe

01:14:14.640 | in his "Angels and Devils."

01:14:17.240 | And he learned about this from Coxeter,

01:14:19.800 | and he think that's a very nice thing,

01:14:22.720 | and so I represent this infinity

01:14:25.000 | to this kind of geometry.

01:14:26.800 | So it's not quite Euclidean geometry,

01:14:28.160 | it's a bit like it,

01:14:29.240 | that the angels and the devils inhabit.

01:14:31.840 | And their infinity,

01:14:33.400 | by this nice transformation,

01:14:35.120 | you squash their infinity down,

01:14:37.680 | so you can draw it as this nice circle boundary

01:14:40.480 | to their universe.

01:14:43.200 | Now, from our outside perspective,

01:14:45.200 | we can see their infinity as this boundary.

01:14:48.280 | Now, what I'm saying is that it's very like that.

01:14:53.080 | The infinity that we might experience

01:14:56.040 | like those angels and devils in their world

01:14:58.200 | can be thought of as a boundary.

01:15:01.960 | Now, I found this a very useful way

01:15:04.600 | of talking about radiation, gravitational radiation,

01:15:07.920 | and things like that.

01:15:09.880 | It was a trick, mathematical trick.

01:15:12.560 | So now what I'm saying is that

01:15:13.840 | that mathematical trick becomes real,

01:15:17.440 | that somehow the photons,

01:15:19.600 | they need to go somewhere,

01:15:22.280 | because from their perspective,

01:15:25.120 | infinity is just another place.

01:15:27.160 | Now, this is a difficult idea to get your mind around,

01:15:30.640 | so that's one of the reasons cosmologists

01:15:34.040 | are finding a lot of trouble taking me seriously.

01:15:37.160 | But to me, it's not such a wild idea.

01:15:39.880 | What's on the other side of that infinity?

01:15:42.080 | You have to think, why am I allowed to think of this?

01:15:45.280 | Because photons don't have any mass.

01:15:48.880 | And we in physics have beautiful ways of measuring time.

01:15:53.560 | There are incredibly precise clocks,

01:15:55.880 | atomic and nuclear clocks, unbelievably precise.

01:15:59.560 | Why are they so precise?

01:16:01.600 | Because of the two most famous equations

01:16:04.600 | of 20th century physics.

01:16:06.760 | One of them is Einstein's E equals MC squared.

01:16:09.960 | What's that tell us?

01:16:11.040 | Energy and mass are equivalent.

01:16:13.920 | The other one is even older than that,

01:16:16.600 | still 20th century, only just.

01:16:18.480 | Max Planck, E equals h nu.

01:16:22.600 | Nu is a frequency, h is a constant, again, like C.

01:16:26.400 | E is energy.

01:16:27.960 | Energy and frequency are equivalent.

01:16:30.640 | Put the two together,

01:16:33.040 | energy and mass are equivalent, Einstein,

01:16:34.920 | energy and frequency are equivalent, Max Planck.

01:16:37.280 | Put the two together, mass and frequency are equivalent.

01:16:41.400 | Absolutely basic physical principle.

01:16:44.040 | If you have a massive entity, a massive particle,

01:16:47.480 | it is a clock with a very, very precise frequency.

01:16:51.960 | It's not, you can't directly use it,

01:16:54.960 | you have to scale it down.

01:16:56.080 | So your atomic and nuclear clocks,

01:16:57.600 | but that's the basic principle.

01:16:59.120 | You scale it down to something you can actually perceive.

01:17:02.200 | But it's the same principle.

01:17:03.800 | If you have mass, you have beautiful clocks.

01:17:06.760 | But the other side of that coin is,

01:17:10.320 | if you don't have mass, you don't have clocks.

01:17:13.920 | If you don't have clocks, you don't have rulers.

01:17:18.040 | You don't have scale.

01:17:20.160 | - So you don't have space and time.

01:17:21.360 | - You don't have a measure of the scale of space and time.

01:17:24.360 | - Oh, scale of space and time.

01:17:26.480 | - You do have the structure,

01:17:29.320 | what's called the conformal structure.

01:17:30.840 | You see, it's what the angels and devils have.

01:17:33.080 | If you look at the eye of the devil,

01:17:35.040 | no matter how close to the boundary it is,

01:17:36.880 | it has the same shape, but it has a different size.

01:17:40.800 | So you can scale up and you can scale down,

01:17:43.360 | but you mustn't change the shape.

01:17:45.280 | So it's basically the same idea,

01:17:48.520 | but applied to space-time now.

01:17:50.720 | In the very remote future,

01:17:52.560 | you have things which don't measure the scale,

01:17:55.680 | but the shape, if you like, is still there.

01:17:58.440 | Now that's in the remote future.

01:17:59.920 | Now I'm gonna do the exact opposite.

01:18:01.960 | Now I'm gonna go way back into the Big Bang.

01:18:04.640 | Now as you get there, things get hotter and hotter,

01:18:08.080 | denser and denser.

01:18:09.400 | What's the universe dominated by?

01:18:13.000 | Particles moving around almost with the speed of light.

01:18:16.560 | When they get almost with the speed of light,

01:18:19.040 | okay, they begin to lose the mass too.

01:18:21.800 | So for a completely opposite reason,

01:18:24.240 | they lose the sense of scale as well.

01:18:26.840 | So my crazy idea is the Big Bang and a remote future,

01:18:32.200 | they seem completely different.

01:18:33.440 | One is extremely dense, extremely hot.

01:18:36.080 | The other's very, very rarefied and very, very cold.

01:18:39.720 | But if you squash one down by this conformal scaling,

01:18:42.760 | you get the other.

01:18:44.240 | So although they look and feel very different,

01:18:47.940 | they're really almost the same.

01:18:50.360 | The remote future on the other side,

01:18:53.120 | I'm claiming is that, where do the photons go?

01:18:55.520 | They go into the next Big Bang.

01:18:57.200 | You've got to get your mind around that crazy idea.

01:19:01.160 | - Taking a step on the other side

01:19:03.120 | of the place that is infinity.

01:19:05.600 | Okay, but-- - Yes.

01:19:07.200 | So I'm saying the other side of our Big Bang,

01:19:09.000 | now I'm going back into the Big Bang.

01:19:10.600 | - Back, backwards. - There was the remote future

01:19:12.360 | of a previous eon.

01:19:13.760 | - Previous eon.

01:19:15.040 | - And what I'm saying is that previous eon,

01:19:17.560 | there are signals coming through to us,

01:19:20.200 | which we can see and which we do see.

01:19:23.760 | And these are both signals,

01:19:25.100 | the two main signals are to do with black holes.

01:19:29.440 | One of them is the collisions between black holes,

01:19:33.040 | and as they spiral into each other,

01:19:35.200 | they release a lot of energy

01:19:36.960 | in the form of gravitational waves.

01:19:39.120 | Those gravitational waves get through

01:19:42.200 | in a certain form into the next eon.

01:19:44.160 | - That's fascinating that there's some,

01:19:46.240 | I mean, maybe you can correct me if I'm wrong,

01:19:49.040 | but that means that some information can travel--

01:19:51.560 | - Yes. - From another eon.

01:19:53.320 | - Exactly.

01:19:54.240 | - That is fascinating.

01:19:58.880 | I mean, I've seen somewhere described

01:20:01.720 | sort of the discussion of the Fermi paradox,

01:20:05.840 | that if there's intelligent life--

01:20:08.280 | - Yes.

01:20:09.840 | - Communication immediately takes you there, so--

01:20:13.160 | - We have a paper, my colleague, Vahe Guzajan,

01:20:17.000 | who I worked with on these ideas for a while,

01:20:19.840 | we have a crazy paper on that, yes.

01:20:21.760 | Looking at the Fermi paradox, yes.

01:20:23.560 | - Right, so if the universe is just cycling

01:20:26.000 | over and over and over,

01:20:27.280 | punctuated by the singularity of the Big Bang,

01:20:32.280 | and then intelligent,

01:20:34.920 | or any kind of intelligent systems

01:20:36.840 | can communicate through from eon to eon,

01:20:39.640 | why haven't we heard anything from our alien friends?

01:20:44.640 | - 'Cause we don't know how to look.

01:20:47.000 | - That's fundamentally the reason, is we--

01:20:48.920 | - I don't know, you see, it's speculation.

01:20:51.840 | I mean, the SETI program is a reasonable thing to do,

01:20:55.520 | but still speculation.

01:20:57.000 | It's trying to say, okay, maybe not too far away

01:21:01.880 | was a civilization which got there first, before us,

01:21:05.640 | early enough that they could send us signals,

01:21:08.760 | but how far away would you need to go before,

01:21:11.080 | I mean, I don't know, we have so little knowledge about that

01:21:14.520 | we haven't seen any signals yet, but it's worth looking.

01:21:16.960 | It's worth looking.

01:21:18.280 | What I'm trying to say,

01:21:19.440 | here's another possible place where you might look.

01:21:22.600 | Now you're not looking at civilizations

01:21:24.600 | which got there first.

01:21:26.240 | You're looking at those civilizations

01:21:27.960 | which were so successful, probably a lot more successful

01:21:31.240 | than they're more likely to be by the looks of things,

01:21:33.920 | which knew how to handle their own global warming

01:21:38.080 | or whatever it is and to get through it all

01:21:40.480 | and to live to a ripe old age in the sense of a civilization

01:21:45.440 | to the extent that they could harness signals,

01:21:49.160 | that they could propagate through for some reason

01:21:52.320 | of their own desires, whatever we wouldn't know,

01:21:55.680 | to other civilizations which might be able

01:21:58.560 | to pick up the signals.

01:22:00.200 | But what kind of signals would they be?

01:22:01.960 | I haven't the foggiest.

01:22:03.240 | - Let me ask the question.

01:22:06.960 | What to you is the most beautiful idea in physics

01:22:09.920 | or mathematics or the art at the intersection of the two?

01:22:14.160 | - I'm gonna have to say complex analysis.

01:22:17.180 | I might've said infinities.

01:22:20.680 | One of the most single most beautiful idea, I think,

01:22:23.440 | is the fact that you can have infinities

01:22:25.560 | of different sizes and so on.

01:22:27.320 | But that's in a way, I think, complex analysis.

01:22:30.800 | It's got so much magic in it.

01:22:33.400 | It's a very simple idea.

01:22:35.360 | You take these, you take numbers, you take the integers

01:22:41.160 | and then you fill them up into the fractions

01:22:43.120 | and the real numbers.

01:22:44.640 | You imagine you're trying to measure a continuous line.

01:22:47.520 | And then you think of how you can solve equations.

01:22:50.400 | Then what about X squared equals minus one?

01:22:53.400 | Well, there's no real number which satisfies that.

01:22:57.460 | So you have to think of, well, there's a number called I.

01:23:00.480 | You think you invent it.

01:23:02.340 | Well, in a certain sense, it's there already.

01:23:05.160 | But this number, when you add that square root

01:23:07.440 | of minus one to it, you have what's called

01:23:09.260 | the complex numbers.

01:23:10.960 | And they're an incredible system.

01:23:12.740 | If you like, you put one little thing in,

01:23:15.720 | you put square root of minus one in

01:23:17.320 | and you get how much benefit out of it?

01:23:20.640 | All sorts of things that you'd never imagined before.

01:23:23.400 | And it's that amazing, all hiding there

01:23:27.760 | in putting that square root of minus one in.

01:23:30.160 | - So in a sense-- - I think that's

01:23:31.200 | the most magical thing I've seen in mathematics or physics.

01:23:34.040 | And it's in quantum mechanics.

01:23:35.560 | - In quantum mechanics.

01:23:36.400 | - You see, it's there already.

01:23:38.200 | You might think, what's it doing there?

01:23:39.720 | Okay, just a nice, beautiful piece of mathematics.

01:23:41.640 | And then suddenly we see, nope.

01:23:44.160 | It's the very crucial basis of quantum mechanics.

01:23:47.200 | It's there in the way the world works.

01:23:49.520 | - So on the question of whether math

01:23:50.960 | is discovered or invented, it sounds like

01:23:53.440 | you may be suggesting that partially it's possible

01:23:56.160 | that math is indeed discovered.

01:23:57.840 | - Oh, absolutely, yes.

01:23:59.660 | No, it's more like archeology than you might think.

01:24:02.160 | Yes, yes.

01:24:03.880 | - So let me ask the most ridiculous,

01:24:06.520 | maybe the most important question.

01:24:08.640 | What is the meaning of life?

01:24:12.400 | What gives your life fulfillment, purpose,

01:24:15.000 | happiness, and meaning?

01:24:15.960 | Why do you think we're here on this?

01:24:18.240 | Given all the big bang and the infinities

01:24:20.280 | of photons that we've talked about.

01:24:21.600 | - All I would say, I think it's not a stupid question.

01:24:24.400 | (laughs)

01:24:26.560 | I mean, there are some people, you know,

01:24:28.160 | many of my colleagues who are scientists,

01:24:29.760 | and they say, well, that's a stupid question,

01:24:31.280 | meaning, well, we're just here because

01:24:33.560 | things came together and produced life and so what.

01:24:36.120 | I think there's more to it.

01:24:39.240 | But what there is that's more to it,

01:24:41.040 | I have really much idea.

01:24:43.080 | - And it might be somehow connected to the mechanisms

01:24:45.400 | of consciousness that we've been talking about,

01:24:47.400 | the mystery there.

01:24:48.520 | - Yeah, yeah.

01:24:49.480 | It's connected with all sorts of, yeah,

01:24:51.000 | I think these things are tied up in ways which are,

01:24:53.560 | you see, I tend to think the mystery of consciousness

01:24:56.720 | is tied up with the mystery of quantum mechanics

01:25:00.960 | and how it fits in with the classical world,

01:25:04.000 | and that's all to do with the mystery of complex numbers.

01:25:07.440 | And there are mysteries there which look like

01:25:11.520 | mathematical mysteries, but they seem to have a bearing

01:25:15.720 | on the way the physical world operates.

01:25:17.680 | We're scratching the surface.

01:25:20.760 | We have a long, huge way to go

01:25:22.960 | before we really understand that.

01:25:24.840 | - And it's a beautiful idea that the depth,

01:25:28.360 | the mathematical depth could be discovered,

01:25:30.680 | and then there's tragedies of Gato's incompleteness

01:25:33.640 | along the way that we'll have to somehow

01:25:35.360 | figure our ways around.

01:25:36.640 | - Yeah.

01:25:38.920 | - So, Roger, it was a huge honor to talk to you.

01:25:42.080 | Thank you so much for your time today.

01:25:43.440 | - It's been my pleasure.

01:25:44.560 | Thank you.

01:25:46.080 | - Thanks for listening to this conversation

01:25:47.600 | with Roger Penrose, and thank you

01:25:49.800 | to our presenting sponsor, Cash App.

01:25:52.000 | Please consider supporting this podcast

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01:26:03.920 | If you enjoy this podcast, subscribe on YouTube,

01:26:06.400 | review it with Five Stars and Apple Podcasts,

01:26:09.000 | support on Patreon, or simply connect with me on Twitter

01:26:12.440 | at Lex Friedman.

01:26:14.000 | And now, let me leave you with some words of wisdom

01:26:16.920 | that Roger Penrose wrote in his book,

01:26:19.200 | "The Emperor's New Mind."

01:26:20.600 | Beneath all this technicality is the feeling

01:26:24.400 | that it is indeed, quote unquote, obvious

01:26:28.000 | that the conscious mind cannot work like a computer,

01:26:31.160 | even though much of what is involved

01:26:33.000 | in mental activity might do so.

01:26:35.400 | This is the kind of obviousness that a child can see,

01:26:39.480 | though the child may later in life become browbeaten

01:26:42.680 | into believing that the obvious problems

01:26:44.720 | are quote unquote, non-problems,

01:26:47.200 | to be argued into nonexistence by careful reasoning

01:26:51.000 | and clever choices of definition.

01:26:52.820 | Children sometimes see things clearly

01:26:56.440 | that are obscured in later life.

01:26:59.040 | We often forget the wonder that we felt as children

01:27:02.360 | when the cares of the quote unquote, real world

01:27:05.200 | have begun to settle on our shoulders.

01:27:07.760 | Children are not afraid to pose basic questions

01:27:10.440 | that may embarrass us as adults to ask.

01:27:13.560 | What happens to each of our streams of consciousness

01:27:15.680 | after we die?

01:27:17.160 | Where was it before we were born?

01:27:19.520 | Might we become or have been someone else?

01:27:23.160 | Why do we perceive it all?

01:27:25.120 | Why are we here?

01:27:26.840 | Why is there a universe here at all

01:27:28.560 | in which we can actually be?

01:27:30.840 | These are puzzles that tend to come

01:27:32.560 | with the awakenings of awareness in any of us,

01:27:35.920 | and no doubt with the awakening of self-awareness

01:27:39.920 | within whichever creature or other entity it first came.

01:27:43.620 | Thank you for listening and hope to see you next time.

01:27:48.240 | (upbeat music)

01:27:50.820 | (upbeat music)

01:27:53.400 | [BLANK_AUDIO]

Roger Penrose: Physics of Consciousness and the Infinite Universe | Lex Fridman Podcast #85

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