Roger Penrose: Physics of Consciousness and the Infinite Universe
物理与宇宙学数学音乐与艺术生物与进化技术与编程
🤖
AI 智能总结
罗杰·彭罗斯谈意识的物理学与无限宇宙
这是 Lex Fridman 与牛津大学物理学家、数学家、哲学家罗杰·彭罗斯的深度对话。彭罗斯探讨了他关于意识的量子理论（Orch OR）、宇宙的循环共形宇宙学（CCC）、哥德尔不完备定理对 AI 的含义，以及数学柏拉图主义。
意识量子力学Orch OR宇宙学哥德尔定理数学柏拉图主义AI局限
罗杰·彭罗斯爵士是牛津大学数学物理学荣誉教授，因对黑洞奇点的数学证明与史蒂芬·霍金共同获得 2020 年诺贝尔物理学奖，著有《皇帝的新脑》《通往实在之路》等影响深远的著作。
📌 核心观点
- Orch OR 理论：彭罗斯与麻醉学家 Stuart Hameroff 共同提出，意识源于神经元微管中的量子引力效应。他认为意识不能被图灵机模拟，因为人类的数学直觉超越了任何形式系统的能力。
- 哥德尔定理与 AI：彭罗斯认为哥德尔不完备定理证明了人类数学家能够理解某些真理，而这些真理无法被任何算法系统证明，这意味着强 AI（真正理解的机器）在原则上是不可能的。
- 循环共形宇宙学（CCC）：彭罗斯提出宇宙经历无限次「大爆炸-膨胀-热寂」的循环，每个循环结束时的信息通过共形几何传递到下一个循环，他声称在 CMB 中发现了前一个宇宙的痕迹。
- 数学柏拉图主义：彭罗斯坚信数学对象（如曼德布罗特集合）是被发现而非被发明的，它们存在于独立于物理世界的柏拉图领域，这是他哲学体系的核心。
- 对 AI 意识的怀疑：彭罗斯认为当前的 AI 系统，无论多么复杂，都不具备真正的理解或意识，因为它们本质上是算法系统，而意识需要非算法的量子过程。
✨ 金句摘录
彭罗斯：孩子们不害怕提出那些让成年人感到尴尬的基本问题——这正是我写作的动力。
彭罗斯：哥德尔定理告诉我们，人类数学家能够理解某些真理，而这些真理无法被任何算法系统证明。
彭罗斯：曼德布罗特集合不是被发明的，它是被发现的——它存在于某个独立于我们思维的领域。
📋 章节目录
暂无章节信息
🔑 关键词
donquantumgotconsciousnessmechanicsgoingthoughtunderstandingcomputationuniversebangputrulesinfinitystatedoingbookconscioustheorysaying
💬 精彩语录
暂无语录
🎙️ 完整对话（2052 条）
Lex Fridman (00:00.000)
The following is a conversation with Roger Penrose,
以下是与罗杰·彭罗斯的对话，
Lex Fridman (00:02.780)
physicist, mathematician, and philosopher
物理学家、数学家和哲学家
Lex Fridman (00:05.300)
at University of Oxford.
在牛津大学。
Lex Fridman (00:07.020)
He has made fundamental contributions in many disciplines
他在许多学科领域做出了基础性贡献
Lex Fridman (00:10.860)
from the mathematical physics of general relativity
来自广义相对论的数学物理
Lex Fridman (00:13.340)
and cosmology to the limitations
和宇宙学的局限性
Lex Fridman (00:15.780)
of a computational view of consciousness.
意识的计算观点。
Roger Penrose (00:18.660)
In his book, The Emperor's New Mind,
在他的著作《皇帝的新思想》中，
Lex Fridman (00:20.820)
Roger writes that, quote,
罗杰写道，引用，
Roger Penrose (00:22.820)
"'Children are not afraid to pose basic questions
“‘孩子们不害怕提出基本问题
Lex Fridman (00:26.160)
that may embarrass us as adults to ask.'
这可能会让我们作为成年人感到尴尬。
Roger Penrose (00:29.900)
In many ways, my goal with this podcast
从很多方面来说，我的播客目标
Lex Fridman (00:32.000)
is to embrace the inner child
就是拥抱内在的孩子
Roger Penrose (00:33.680)
that is not constrained by how one should behave,
不受人们行为方式的限制，
Lex Fridman (00:36.540)
speak, and think in the adult world.
在成人的世界里说话、思考。
Roger Penrose (00:41.180)
Roger is one of the most important minds of our time,
罗杰是我们这个时代最重要的思想家之一
Lex Fridman (00:44.780)
so it was truly a pleasure and an honor to talk with him.
所以与他交谈确实是一种愉快和荣幸。
Roger Penrose (00:49.140)
This conversation was recorded
这段对话被录音
Lex Fridman (00:50.620)
before the outbreak of the pandemic.
疫情爆发之前。
Roger Penrose (00:52.920)
For everyone feeling the medical, psychological,
对于每个感受到医学、心理、
Lex Fridman (00:55.820)
and financial burden of the crisis,
Roger Penrose (00:57.740)
I'm sending love your way.
Lex Fridman (00:59.780)
Stay strong, we're in this together, we'll beat this thing.
Roger Penrose (01:04.100)
This is the Artificial Intelligence Podcast.
Lex Fridman (01:06.660)
If you enjoy it, subscribe on YouTube,
Roger Penrose (01:08.860)
review it with five stars on Apple Podcast,
Lex Fridman (01:11.220)
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Roger Penrose (01:12.620)
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Lex Fridman (01:14.660)
at Lex Friedman, spelled F R I D M A N.
Roger Penrose (01:18.780)
As usual, I'll do a few minutes of ads now
Lex Fridman (01:21.180)
and never any ads in the middle
Roger Penrose (01:22.380)
that can break the flow of the conversation.
Lex Fridman (01:24.580)
I hope that works for you
Lex Fridman (01:25.720)
and doesn't hurt the listening experience.
Lex Fridman (01:27.860)
Quick summary of the ads.
Roger Penrose (01:29.340)
Two sponsors, ExpressVPN and Cash App.
Lex Fridman (01:33.380)
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Roger Penrose (01:35.500)
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Roger Penrose (01:46.260)
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Roger Penrose (02:05.060)
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Lex Fridman (02:06.780)
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Roger Penrose (02:09.460)
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Lex Fridman (02:11.260)
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Roger Penrose (02:13.740)
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Lex Fridman (02:15.460)
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Roger Penrose (02:18.040)
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Lex Fridman (02:21.040)
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Roger Penrose (02:22.980)
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Lex Fridman (02:25.460)
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Lex Fridman (02:28.480)
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Roger Penrose (02:34.340)
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Lex Fridman (02:38.500)
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and STEM education for young people around the world.
Lex Fridman (02:45.120)
This show is sponsored by ExpressVPN.
Roger Penrose (02:47.700)
Get it at expressvpn.com slash lexpod
Lex Fridman (02:52.540)
to get a discount and to support this podcast.
Roger Penrose (02:55.580)
I've been using ExpressVPN for many years.
Lex Fridman (02:58.280)
I love it.
Roger Penrose (02:59.300)
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Lex Fridman (03:03.100)
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Lex Fridman (03:04.900)
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Lex Fridman (03:08.340)
is anywhere else in the world.
Roger Penrose (03:10.100)
I might be in Boston now,
Lex Fridman (03:12.040)
but I can make it look like I'm in New York,
Roger Penrose (03:14.220)
London, Paris or anywhere else.
Lex Fridman (03:17.720)
This has a large number of obvious benefits.
Roger Penrose (03:20.380)
Certainly, it allows you to access international versions
Lex Fridman (03:23.300)
of streaming websites like the Japanese Netflix
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or the UK Hulu.
Lex Fridman (03:28.140)
ExpressVPN works on any device you can imagine.
Roger Penrose (03:31.660)
I use it on Linux, shout out to Ubuntu, Windows, Android,
Lex Fridman (03:36.320)
but it's available everywhere else too.
Roger Penrose (03:38.640)
Once again, get it at expressvpn.com slash lexpod
Lex Fridman (03:43.380)
to get a discount and to support this podcast.
Lex Fridman (03:46.440)
And now, here's my conversation with Roger Penrose.
Lex Fridman (03:51.660)
You mentioned in conversation with Eric Weinstein
Roger Penrose (03:54.240)
on the Portal podcast that 2001 Space Odyssey
Lex Fridman (03:57.620)
is your favorite movie.
Roger Penrose (03:59.940)
Which aspect, if you could mention,
Lex Fridman (04:02.100)
of its representation of artificial intelligence,
Lex Fridman (04:05.100)
science, engineering connected with you?
Lex Fridman (04:07.740)
There are all sorts of scenes there which are so amazing.
Lex Fridman (04:11.460)
And how science was so well done.
Lex Fridman (04:14.820)
I mean, people say, oh no, Interstellar is this amazing movie
Roger Penrose (04:19.060)
which is the most scientific movie.
Lex Fridman (04:21.700)
I thought it's not a patch on 2001.
Roger Penrose (04:24.660)
I mean, 2001, they really went into all sorts of details.
Lex Fridman (04:29.260)
And regarding getting the free fall well done and everything,
Roger Penrose (04:33.220)
I thought it was extremely well done.
Lex Fridman (04:35.940)
So just the details were mesmerizing in terms of this.
Lex Fridman (04:38.980)
And also things like the scene where at the beginning
Lex Fridman (04:43.180)
they have these sort of human ancestors
Roger Penrose (04:45.700)
which are sort of apes becoming humans.
Lex Fridman (04:49.540)
The monolith.
Roger Penrose (04:50.820)
Yes, and well, it's the one where he throws the bone
Lex Fridman (04:53.900)
up into the air and then it becomes this.
Roger Penrose (04:57.220)
I mean, that's an amazing sequence there.
Lex Fridman (05:00.140)
What do you make of the monolith?
Roger Penrose (05:01.860)
Does it have any scientific or philosophical meaning to you,
Lex Fridman (05:06.140)
this kind of thing that sparks innovation?
Roger Penrose (05:08.220)
Not really.
Lex Fridman (05:09.060)
That comes from Arthur C. Clarke.
Roger Penrose (05:12.260)
I was always a great fan of Arthur C. Clarke.
Lex Fridman (05:14.220)
So it's just a nice plot device.
Roger Penrose (05:16.020)
Yeah, that plot is excellent, yes.
Lex Fridman (05:18.140)
So Hal 9000 decides to get rid of the astronauts
Roger Penrose (05:22.020)
because he, it, she believes that they will interfere
Lex Fridman (05:26.900)
with the mission.
Roger Penrose (05:27.740)
That's right.
Lex Fridman (05:28.580)
Yeah, well, there you are.
Roger Penrose (05:29.420)
It's this view.
Lex Fridman (05:30.380)
I don't know whether I disagree with it
Roger Penrose (05:31.580)
because in a certain sense it was telling you it's wrong.
Lex Fridman (05:35.180)
See, the machine seemed to think it was superior
Roger Penrose (05:39.460)
to the human and so it was entitled to get rid
Lex Fridman (05:45.060)
of the human beings and run the show itself.
Lex Fridman (05:47.380)
Well, do you think Hal did the right thing?
Lex Fridman (05:49.460)
Do you think Hal's flawed evil?
Roger Penrose (05:52.020)
Or if we think about systems like Hal,
Lex Fridman (05:55.340)
would we want Hal to do the same thing in the future?
Lex Fridman (05:58.020)
What was the flaw there?
Lex Fridman (05:58.940)
Well, you're basically touching on questions.
Roger Penrose (06:01.660)
You see, it's one supposed to believe
Lex Fridman (06:04.540)
that Hal was actually conscious.
Roger Penrose (06:06.420)
I mean, it was played rather that way,
Lex Fridman (06:10.140)
as though Hal was a conscious being.
Roger Penrose (06:13.500)
Because Hal showed some pain, some cognizance,
Lex Fridman (06:19.820)
Hal appeared to be cognizant of what it means to die.
Roger Penrose (06:24.180)
Yes.
Lex Fridman (06:25.020)
And therefore had an inkling of consciousness.
Roger Penrose (06:28.220)
Yeah, I mean, I'm not sure that aspect
Lex Fridman (06:30.780)
of it was made completely clear,
Roger Penrose (06:32.700)
whether Hal was really just a very sophisticated computer,
Lex Fridman (06:37.100)
which really didn't actually have these feelings
Lex Fridman (06:39.300)
and somehow, but you're right,
Lex Fridman (06:42.180)
it didn't like the idea of being turned off.
Lex Fridman (06:45.620)
How does it change things if Hal was or wasn't conscious?
Lex Fridman (06:49.700)
Well, it might say that it would be wrong to turn it off
Roger Penrose (06:53.100)
if it was actually conscious.
Lex Fridman (06:55.180)
I mean, these questions arise if you think.
Roger Penrose (06:57.340)
I mean, AI, one of the ideas,
Lex Fridman (07:00.020)
it's sort of a mixture in a sense.
Roger Penrose (07:01.460)
You say, if it's trying to do everything a human can do,
Lex Fridman (07:05.260)
and if you take the view that consciousness
Roger Penrose (07:08.660)
is something which would come along
Lex Fridman (07:10.500)
when the computer is sufficiently complicated,
Roger Penrose (07:13.420)
sufficiently whatever criterion you use
Lex Fridman (07:16.460)
to characterize its consciousness
Roger Penrose (07:20.860)
in terms of some computational criteria,
Lex Fridman (07:24.860)
computational criterion.
Lex Fridman (07:28.620)
So how does consciousness change our evaluation
Lex Fridman (07:33.580)
of the decision that Hal made?
Roger Penrose (07:35.940)
I guess I was trying to say
Lex Fridman (07:36.780)
that people are a bit confused about this,
Roger Penrose (07:38.940)
because if they say these machines will become conscious,
Lex Fridman (07:42.100)
but just simply because it's a degree of computation,
Lex Fridman (07:45.300)
and when you get beyond that certain degree of computation,
Lex Fridman (07:48.260)
it will become conscious,
Roger Penrose (07:49.420)
then of course you have all these problems.
Lex Fridman (07:52.340)
I mean, you might say, well,
Roger Penrose (07:53.380)
one of the reasons you're doing AI
Lex Fridman (07:55.100)
is because you want to send a device
Roger Penrose (07:57.100)
out to some distant planet,
Lex Fridman (07:59.060)
and you don't want to send a human out there,
Roger Penrose (08:01.180)
because then you'd have to bring it back again,
Lex Fridman (08:02.780)
and that costs you far more
Roger Penrose (08:04.900)
than just sending it there and leaving it there.
Lex Fridman (08:07.100)
But if this device is actually a conscious entity,
Roger Penrose (08:10.020)
then you have to face up to the fact that that's immoral.
Lex Fridman (08:13.060)
And so the mere fact that you're making some AI device
Lex Fridman (08:17.820)
and thinking that removes your responsibility to it
Lex Fridman (08:24.140)
would be incorrect.
Lex Fridman (08:25.820)
And so this is a sign of flaw in that kind of viewpoint.
Lex Fridman (08:29.700)
I'm not sure how people who take it very seriously,
Roger Penrose (08:35.460)
I mean, I had this curious conversation
Lex Fridman (08:37.140)
with, I'm going to forget names, I'm afraid,
Roger Penrose (08:40.780)
because this is what happens to me at the wrong moment,
Lex Fridman (08:43.860)
Hofstadter, Douglas Hofstadter.
Roger Penrose (08:45.860)
Douglas Hofstadter, yeah.
Lex Fridman (08:46.820)
And he'd written this book,
Roger Penrose (08:48.860)
God Will Let You Up, which I liked.
Lex Fridman (08:50.340)
I thought it was a fantastic book.
Lex Fridman (08:52.300)
But I didn't agree with his conclusion
Lex Fridman (08:55.700)
from Gödel's theorem.
Roger Penrose (08:56.580)
I think he got it wrong, you see.
Lex Fridman (08:58.580)
Well, I'll just tell you my story, you see,
Roger Penrose (09:01.220)
because I'd never met him.
Lex Fridman (09:02.700)
And then I knew I was going to meet him,
Roger Penrose (09:04.740)
the occasion I realized he was coming in,
Lex Fridman (09:06.860)
he wanted to talk to me, and I said, that's fine.
Lex Fridman (09:09.140)
And I thought in my mind,
Lex Fridman (09:10.460)
well, I'm going to paint him into a corner, you see,
Roger Penrose (09:12.620)
because I'll use his arguments to convince him
Lex Fridman (09:15.780)
that certain numbers are conscious.
Roger Penrose (09:19.340)
Some integers, large enough integers are actually conscious.
Lex Fridman (09:22.620)
And this was going to be my reductio ad absurdum.
Lex Fridman (09:25.420)
So I started having this argument with him.
Lex Fridman (09:26.900)
He simply leapt into the corner.
Roger Penrose (09:28.660)
He didn't even need to be painted into it.
Lex Fridman (09:31.020)
He took the view that certain numbers were conscious.
Roger Penrose (09:33.900)
I thought that was a reductio ad absurdum,
Lex Fridman (09:35.780)
but he seemed to think it was perfectly
Roger Penrose (09:37.620)
a reasonable point of view.
Lex Fridman (09:38.860)
Without the absurdum there.
Roger Penrose (09:40.620)
Yes.
Lex Fridman (09:41.540)
Interesting, but the thing you mentioned about how
Roger Penrose (09:44.580)
is the intuition that a lot of the people,
Lex Fridman (09:46.940)
at least in the artificial intelligence world,
Roger Penrose (09:48.900)
had and have, I think.
Lex Fridman (09:51.500)
They don't make it explicit,
Lex Fridman (09:52.700)
but that if you increase the power of computation,
Lex Fridman (09:56.820)
naturally consciousness will emerge.
Roger Penrose (09:58.980)
Yes, I think that's what they think.
Lex Fridman (10:00.300)
But basically that's because
Roger Penrose (10:01.300)
they can't think of anything else.
Lex Fridman (10:02.740)
Well, that's right.
Lex Fridman (10:03.580)
And so it's a reasonable thing.
Lex Fridman (10:05.340)
I mean, you think, what does the brain do?
Roger Penrose (10:06.540)
Well, it does do a lot of computation.
Lex Fridman (10:09.140)
I think most of what you actually call computation
Roger Penrose (10:11.540)
is done by the cerebellum.
Lex Fridman (10:13.260)
I mean, this is one of the things
Roger Penrose (10:15.620)
that people don't much mention.
Lex Fridman (10:17.820)
I mean, I come to this subject from the outside
Lex Fridman (10:19.740)
and certain things strike me,
Lex Fridman (10:21.860)
which you hardly ever hear mentioned.
Roger Penrose (10:24.700)
I mean, you hear mentioned about the left right business.
Lex Fridman (10:28.420)
They move your right arm,
Roger Penrose (10:30.340)
that's the left side of the brain
Lex Fridman (10:31.900)
and so on and all that sort of stuff.
Lex Fridman (10:34.940)
And it's more than that.
Lex Fridman (10:36.780)
If you have these plots of different parts of the brain,
Roger Penrose (10:40.460)
there are two of these things called the homunculi,
Lex Fridman (10:43.300)
which you see these pictures of a distorted human figure
Lex Fridman (10:47.500)
and showing different parts of the brain,
Lex Fridman (10:51.420)
controlling different parts of the body.
Lex Fridman (10:53.140)
And it's not simply things like,
Lex Fridman (10:55.900)
okay, the right hand is controlled
Lex Fridman (10:58.020)
and both sensory and motor on the left side,
Lex Fridman (11:03.020)
left hand on the right side.
Roger Penrose (11:04.820)
It's more than that.
Lex Fridman (11:05.940)
Vision is the back basically,
Roger Penrose (11:08.620)
your feet at the top.
Lex Fridman (11:11.020)
And it's as though it's about the worst organization
Roger Penrose (11:13.060)
you could imagine.
Lex Fridman (11:14.820)
So it can't just be a mistake in nature.
Roger Penrose (11:17.540)
There's something going on there.
Lex Fridman (11:19.460)
And this is made more pronounced
Roger Penrose (11:22.660)
when you think of the cerebellum.
Lex Fridman (11:25.660)
The cerebellum has,
Roger Penrose (11:27.540)
when I was first thinking about these things,
Lex Fridman (11:29.340)
I was told that it had half as many neurons
Roger Penrose (11:32.020)
or something like that, comparable.
Lex Fridman (11:33.940)
And now they tell me it's got far more neurons
Roger Penrose (11:36.500)
than the cerebrum, and cerebrum is this sort of
Lex Fridman (11:39.780)
convoluted thing at the top people always talk about.
Roger Penrose (11:42.020)
Cerebellum is this thing just looks a bit like
Lex Fridman (11:44.220)
a ball of wool right at the back underneath them.
Roger Penrose (11:47.900)
It's got more neurons.
Lex Fridman (11:49.460)
It's got more connections.
Roger Penrose (11:51.620)
Computationally, it's got much more going on
Lex Fridman (11:55.140)
than this from the cerebrum.
Lex Fridman (11:58.420)
But as far as we know, that's slightly controversial,
Lex Fridman (12:01.380)
the cerebellum is entirely unconscious.
Lex Fridman (12:04.820)
So the actions, you have a pianist
Lex Fridman (12:07.300)
who plays an incredible piece of music
Lex Fridman (12:09.020)
and think of, and he moves his little finger
Lex Fridman (12:11.940)
into this little key to get it, hit it,
Roger Penrose (12:14.140)
just the right moment.
Lex Fridman (12:15.900)
Does he or she consciously will that movement?
Roger Penrose (12:20.780)
No.
Lex Fridman (12:23.060)
Okay, the consciousness is coming in.
Roger Penrose (12:24.660)
It's probably to do with the feeling
Lex Fridman (12:26.060)
of the piece of music that's being performed
Lex Fridman (12:28.780)
and that sort of thing, which is going on.
Lex Fridman (12:31.220)
But the details of what's going on are controlled.
Roger Penrose (12:35.020)
I would think almost entirely by the cerebellum.
Lex Fridman (12:38.620)
That's where you have this precision
Lex Fridman (12:40.380)
and the really detailed.
Lex Fridman (12:44.020)
Once you get, I mean, you think of a tennis player
Roger Penrose (12:47.260)
or something, does that tennis player
Lex Fridman (12:48.860)
think exactly which muscles should be moved
Lex Fridman (12:51.940)
in what direction and so on?
Lex Fridman (12:52.940)
No, of course not.
Lex Fridman (12:54.380)
But he or she will maybe think,
Lex Fridman (12:56.220)
well, if the ball is angled in such a way in that corner,
Roger Penrose (12:59.340)
that will be tricky for the opponent.
Lex Fridman (13:02.020)
And the details of that are all done
Roger Penrose (13:06.420)
largely with the cerebellum.
Lex Fridman (13:08.740)
That's where all the precise motions,
Lex Fridman (13:11.540)
but it's unconscious.
Lex Fridman (13:13.060)
So why is it interesting to you
Roger Penrose (13:14.420)
that so much computation is done in the cerebellum
Lex Fridman (13:17.940)
and yet it is unconscious?
Roger Penrose (13:19.340)
Because it doesn't, it's the view
Lex Fridman (13:21.980)
that somehow it's computation
Roger Penrose (13:24.580)
which is producing the consciousness.
Lex Fridman (13:27.340)
And it's here you have an incredible amount
Roger Penrose (13:30.740)
of computation going on.
Lex Fridman (13:33.220)
And as far as we know, it's completely unconscious.
Lex Fridman (13:36.980)
So why, what's the difference?
Lex Fridman (13:39.460)
And I think it's an important thing.
Lex Fridman (13:41.860)
What's the difference?
Lex Fridman (13:43.900)
Why is the cerebrum, all this very peculiar stuff
Roger Penrose (13:47.620)
that very hard to see on a computational perspective,
Lex Fridman (13:51.300)
like having the, everything have to cross over
Roger Penrose (13:53.940)
under the other side and do something
Lex Fridman (13:55.620)
which looks completely inefficient.
Lex Fridman (13:58.300)
And you've got funny things like the frontal lobe
Lex Fridman (14:01.540)
and the, what do we call the lobes?
Lex Fridman (14:04.660)
And the place where they come together,
Lex Fridman (14:07.820)
you have the different parts, the control,
Roger Penrose (14:12.340)
you see one to do with motor
Lex Fridman (14:13.740)
and the other to do with sensory.
Lex Fridman (14:16.340)
And they're sort of opposite each other
Lex Fridman (14:17.900)
rather than being connected by,
Roger Penrose (14:20.860)
it's not as though you've got electrical circuits.
Lex Fridman (14:23.460)
There's something else going on there.
Lex Fridman (14:26.300)
So it's just the idea that it's like a complicated computer
Lex Fridman (14:30.260)
just seems to me to be completely missing the point.
Roger Penrose (14:34.580)
There must be a lot of computation going on,
Lex Fridman (14:37.380)
but the cerebellum seems to be much better at doing that
Roger Penrose (14:40.340)
than the cerebrum is.
Lex Fridman (14:42.820)
So for sure, I think what explains it is like half hope
Lex Fridman (14:47.940)
and half we don't know what's going on.
Lex Fridman (14:49.700)
And therefore from the computer science perspective,
Roger Penrose (14:52.420)
you hope that a Turing machine can be perfectly,
Lex Fridman (14:56.340)
can achieve general intelligence.
Roger Penrose (14:58.020)
Well, you have this wonderful thing about Turing
Lex Fridman (15:02.220)
and Gödel and Church and Curry and various people,
Roger Penrose (15:07.500)
particularly Turing, and I guess Post was the other one.
Lex Fridman (15:11.660)
These people who developed the idea
Roger Penrose (15:14.340)
of what a computation is.
Lex Fridman (15:17.740)
And there were different ideas of what a computation,
Roger Penrose (15:19.900)
developed differently.
Lex Fridman (15:20.740)
I mean, Church's way of doing it,
Roger Penrose (15:21.820)
was very different from Turing's,
Lex Fridman (15:24.620)
but then they were shown to be equivalent.
Lex Fridman (15:26.820)
And so the view emerged that what we mean by computation
Lex Fridman (15:32.060)
is a very clear concept.
Lex Fridman (15:34.820)
And one of the wonderful things that Turing did
Lex Fridman (15:37.860)
was to show that you could have
Lex Fridman (15:40.180)
what we call the universal Turing machine.
Lex Fridman (15:43.260)
It's you just have to have a certain finite device.
Roger Penrose (15:46.300)
Okay, it has to have an unlimited storage space,
Lex Fridman (15:48.580)
which is accessible to it,
Lex Fridman (15:50.180)
but the actual computation, if you like,
Lex Fridman (15:51.960)
is performed by this one universal device.
Lex Fridman (15:55.980)
And so the view comes away,
Lex Fridman (15:57.740)
well, you have this universal Turing machine,
Lex Fridman (16:01.340)
and maybe the brain is something like that,
Lex Fridman (16:03.820)
a universal Turing machine,
Lex Fridman (16:05.140)
and it's got maybe not unlimited storage,
Lex Fridman (16:08.620)
but a huge storage accessible to it.
Lex Fridman (16:12.660)
And this model is one,
Lex Fridman (16:14.380)
which is what's used in ordinary computation.
Roger Penrose (16:17.380)
It's a very powerful model.
Lex Fridman (16:19.260)
And the universallness of computation is very useful.
Roger Penrose (16:24.520)
You could have some problem
Lex Fridman (16:26.180)
and you may not see immediately
Lex Fridman (16:27.580)
how to put it onto a computer,
Lex Fridman (16:29.140)
but if it is something of that nature,
Roger Penrose (16:32.200)
then there are all sorts of subprograms
Lex Fridman (16:36.220)
and subroutines when all the,
Roger Penrose (16:37.580)
I mean, I learned a little bit of computing
Lex Fridman (16:38.940)
when I was a student, but not very much.
Lex Fridman (16:42.580)
But it was enough to get the general ideas.
Lex Fridman (16:45.060)
And there's something really pleasant
Roger Penrose (16:46.480)
about a formal system like that.
Lex Fridman (16:48.980)
Yeah.
Roger Penrose (16:49.820)
Where you can start discussing about what's provable,
Lex Fridman (16:51.420)
what's not, these kinds of things.
Lex Fridman (16:52.740)
And you've got a notion, which is an absolute notion,
Lex Fridman (16:55.340)
this notion of computability,
Lex Fridman (16:56.820)
and you can address when things are,
Lex Fridman (17:00.260)
mathematical problems are computably solvable
Lex Fridman (17:02.820)
and what chance.
Lex Fridman (17:03.660)
So.
Lex Fridman (17:04.500)
And it's a very beautiful area of mathematics,
Lex Fridman (17:06.720)
and it's a very powerful area of mathematics.
Lex Fridman (17:09.700)
And it underlies the whole sort of,
Lex Fridman (17:14.580)
I won't say, the principles of computing machines
Roger Penrose (17:18.500)
that we have today.
Lex Fridman (17:19.700)
Could you say, what is Gayle's Incompleteness Theorem?
Lex Fridman (17:22.820)
And how does it, maybe also say,
Lex Fridman (17:24.860)
is it heartbreaking to you?
Lex Fridman (17:26.500)
And how does it interfere with this notion of computation
Lex Fridman (17:31.100)
and consciousness?
Roger Penrose (17:32.660)
Sure.
Lex Fridman (17:33.500)
Well, the ideas, basically ideas,
Roger Penrose (17:36.060)
which I formulated in my first year
Lex Fridman (17:39.140)
as a graduate student in Cambridge.
Roger Penrose (17:41.540)
I did my undergraduate work in mathematics in London,
Lex Fridman (17:44.700)
and I had a colleague, Ian Percival.
Roger Penrose (17:47.460)
We used to discuss things like computational
Lex Fridman (17:49.780)
and logical systems quite a lot.
Roger Penrose (17:52.300)
I'd heard about Gayle's theorem.
Lex Fridman (17:53.660)
I was a bit worried by the idea that it seemed to say
Roger Penrose (17:55.860)
there were things in mathematics that you could never prove.
Lex Fridman (17:59.620)
And so when I went to Cambridge as a graduate student,
Roger Penrose (18:04.100)
I went to various courses.
Lex Fridman (18:06.900)
You see, I was doing pure mathematics.
Roger Penrose (18:08.540)
I was doing algebraic geometry of a sort.
Lex Fridman (18:11.980)
A little bit different from what my supervisor and people,
Lex Fridman (18:15.280)
but it was algebraic geometry.
Lex Fridman (18:16.780)
Yeah.
Lex Fridman (18:17.620)
And I was interested,
Lex Fridman (18:20.260)
I got particularly interested in three lecture courses
Roger Penrose (18:24.860)
that were nothing to do with what I was supposed
Lex Fridman (18:27.020)
to be doing.
Roger Penrose (18:28.260)
One was a course by Herman Bondy
Lex Fridman (18:30.580)
on Einstein's general theory of relativity,
Roger Penrose (18:33.500)
which was a beautiful course.
Lex Fridman (18:34.620)
He was an amazing lecturer,
Roger Penrose (18:37.540)
brought these things alive, absolutely.
Lex Fridman (18:40.260)
Another was a course on quantum mechanics
Roger Penrose (18:43.360)
given by a great physicist, Paul Dirac.
Lex Fridman (18:47.060)
Very beautiful course in a completely different way.
Roger Penrose (18:50.560)
It was, he was very kind of organized
Lex Fridman (18:52.460)
and never got excited about anything seemingly.
Lex Fridman (18:58.540)
But it was extremely well put together.
Lex Fridman (19:00.640)
And I found that amazing too.
Roger Penrose (19:03.340)
Third course that was nothing to do
Lex Fridman (19:04.780)
with what I should be doing was a course
Roger Penrose (19:06.580)
on mathematical logic.
Lex Fridman (19:08.960)
I got excited, as I say, my discussions with Ian Percival
Roger Penrose (19:12.860)
was incompleteness theorem already deeply
Lex Fridman (19:15.980)
within mathematical logic space.
Lex Fridman (19:18.740)
Were you introduced to it?
Lex Fridman (19:20.200)
I was introduced to it in detail by the course, by Steen.
Lex Fridman (19:25.020)
And he, it was two things he described
Lex Fridman (19:27.820)
which were very fundamental to my understanding.
Roger Penrose (19:31.040)
One was Turing machines and the whole idea
Lex Fridman (19:34.260)
of computability and all that.
Lex Fridman (19:35.820)
So that was all very much part of the course.
Lex Fridman (19:38.300)
The other one was the Gödel theorem.
Lex Fridman (19:41.460)
And it wasn't what I was afraid it was
Lex Fridman (19:43.500)
to tell you there were things in mathematics
Roger Penrose (19:45.180)
you couldn't prove.
Lex Fridman (19:47.060)
It was basically, and he phrased it in a way
Roger Penrose (19:51.340)
which often people didn't.
Lex Fridman (19:53.100)
And if you read Douglas Soft status book,
Roger Penrose (19:54.860)
he doesn't, you see.
Lex Fridman (19:56.420)
But Steen made it very clear.
Lex Fridman (19:58.220)
And also in a sort of public lecture
Lex Fridman (1:00:01.540)
that's the OR part in ORCOR, but the ORC part,
Roger Penrose (1:00:05.420)
that's the OR part at least one can see
Lex Fridman (1:00:08.580)
where we're driving at a theory.
Roger Penrose (1:00:10.260)
You can say it's the quantum choice
Lex Fridman (1:00:13.140)
of going this way or that way,
Lex Fridman (1:00:14.700)
but the ORC part, which is the orchestration of this,
Lex Fridman (1:00:17.700)
is much more mysterious,
Lex Fridman (1:00:19.580)
and how does the brain somehow orchestrate
Lex Fridman (1:00:23.260)
all these individual OR processes
Lex Fridman (1:00:26.580)
into a genuine, genuine conscious experience?
Lex Fridman (1:00:32.500)
And it might be something that's beautifully simple,
Lex Fridman (1:00:35.100)
but we're completely in the dark about.
Lex Fridman (1:00:37.780)
Yeah, I think at the moment, that's the thing,
Roger Penrose (1:00:40.220)
you know, we happily put the word ORC down there
Lex Fridman (1:00:42.940)
to say orchestrated, but that's even more unclear
Lex Fridman (1:00:47.500)
what that really means.
Lex Fridman (1:00:49.020)
Just like the word material, orchestrated, who knows?
Lex Fridman (1:00:54.700)
And we've been dancing a little bit
Lex Fridman (1:00:56.220)
between the word intelligence
Roger Penrose (1:00:58.780)
or understanding and consciousness.
Lex Fridman (1:01:00.980)
Do you kind of see those as sitting
Lex Fridman (1:01:03.060)
in the same space of mystery as we discussed?
Lex Fridman (1:01:05.820)
Yes, well, you see, I tend to say
Roger Penrose (1:01:07.820)
you have understanding and intelligence and awareness,
Lex Fridman (1:01:14.100)
and somehow understanding is in the middle of it, you see.
Roger Penrose (1:01:21.220)
I like to say, could you say of an entity
Lex Fridman (1:01:25.660)
that is actually intelligent
Lex Fridman (1:01:27.860)
if it doesn't have the quality of understanding?
Lex Fridman (1:01:30.380)
Now, you see, I'm using terms I don't even know how to define,
Lex Fridman (1:01:33.740)
but who cares?
Lex Fridman (1:01:34.580)
I'm just relating them.
Roger Penrose (1:01:35.420)
They're somewhat poetic, so if I somehow understand them.
Lex Fridman (1:01:38.500)
Yes, that's right, we don't, exactly.
Lex Fridman (1:01:40.900)
But they're not mathematical in nature.
Lex Fridman (1:01:42.300)
Yes, you see, as a mathematician,
Roger Penrose (1:01:44.100)
I don't know how to define any of them,
Lex Fridman (1:01:45.420)
but at least I can point to the connections.
Lex Fridman (1:01:47.460)
So the idea is intelligence is something
Lex Fridman (1:01:50.260)
which I believe needs understanding,
Roger Penrose (1:01:53.980)
otherwise you wouldn't say it's really intelligence.
Lex Fridman (1:01:56.420)
And understanding needs awareness,
Roger Penrose (1:01:59.460)
otherwise you wouldn't really say it's understanding.
Lex Fridman (1:02:02.020)
Do you say of an entity that understands something,
Roger Penrose (1:02:04.420)
unless it's really aware of it, you know, normal usage.
Lex Fridman (1:02:08.420)
So there's a three sort of awareness,
Roger Penrose (1:02:10.940)
understanding, and intelligence.
Lex Fridman (1:02:13.780)
And I just tend to concentrate on understanding
Roger Penrose (1:02:17.500)
because that's where I can say something.
Lex Fridman (1:02:19.220)
Okay.
Lex Fridman (1:02:20.060)
And that's the Gödel theorem, things like that.
Lex Fridman (1:02:21.940)
But what does it mean to be,
Lex Fridman (1:02:24.900)
perceive the color blue or something?
Lex Fridman (1:02:26.900)
I mean, I'm foggiest.
Roger Penrose (1:02:28.460)
It's a much more difficult question.
Lex Fridman (1:02:31.020)
I mean, is it the same if I see a color blue and you see it?
Roger Penrose (1:02:34.020)
If you're somebody with this condition,
Lex Fridman (1:02:36.540)
what's it called then?
Roger Penrose (1:02:38.260)
Or where you assign a sound to a color.
Lex Fridman (1:02:41.500)
Yeah, yeah, that's right.
Roger Penrose (1:02:42.340)
You get colors and sounds mixed up.
Lex Fridman (1:02:44.700)
And that sort of thing.
Roger Penrose (1:02:45.820)
I mean, an interesting subject.
Lex Fridman (1:02:49.020)
But from the physics perspective,
Roger Penrose (1:02:50.820)
from the fundamentals perspective, we don't.
Lex Fridman (1:02:53.180)
I think we're way off having much understanding
Roger Penrose (1:02:56.260)
what's going on there.
Lex Fridman (1:02:57.860)
In your 2010 book, Cycles of Time,
Roger Penrose (1:03:01.300)
you suggest that another universe may have existed
Lex Fridman (1:03:04.300)
before the Big Bang.
Lex Fridman (1:03:06.220)
Can you describe this idea?
Lex Fridman (1:03:08.740)
First of all, what is the Big Bang?
Roger Penrose (1:03:10.900)
Sounds like a funny word.
Lex Fridman (1:03:13.020)
And what may have been there before it?
Roger Penrose (1:03:17.060)
Yes.
Lex Fridman (1:03:17.900)
Just as a matter of terminology,
Roger Penrose (1:03:19.300)
I don't like to call it another universe.
Lex Fridman (1:03:21.740)
Because when you have another universe,
Roger Penrose (1:03:23.020)
you think of it kind of quite separate from us.
Lex Fridman (1:03:25.500)
But these things, they're not separate.
Roger Penrose (1:03:28.660)
Now the Big Bang, conventional theory.
Lex Fridman (1:03:31.820)
You see, I was actually brought up
Roger Penrose (1:03:34.180)
in the sense of when I started getting
Lex Fridman (1:03:35.900)
interested in cosmology,
Roger Penrose (1:03:36.860)
there was a thing called the Steady State Model,
Lex Fridman (1:03:39.220)
which was sort of philosophically very interesting.
Lex Fridman (1:03:41.340)
And there wasn't a Big Bang in that theory.
Lex Fridman (1:03:43.020)
But somehow, new material was created all the time
Roger Penrose (1:03:46.980)
in the form of hydrogen,
Lex Fridman (1:03:48.060)
and the universe kept on expanding, expanding, expanding,
Lex Fridman (1:03:50.500)
and there was room for more hydrogen.
Lex Fridman (1:03:52.540)
It was a rather philosophically nice picture.
Roger Penrose (1:03:54.940)
It was disproved when the Big Bang,
Lex Fridman (1:03:59.940)
well, when I say the Big Bang,
Roger Penrose (1:04:01.820)
this was theoretically discovered
Lex Fridman (1:04:04.900)
by people trying to solve Einstein's equations
Lex Fridman (1:04:07.860)
and apply it to cosmology.
Lex Fridman (1:04:09.340)
Einstein didn't like the idea.
Roger Penrose (1:04:10.700)
He liked a universe which was there all the time.
Lex Fridman (1:04:14.340)
And he had a model which was there all the time.
Lex Fridman (1:04:16.740)
But then there was this discovery,
Lex Fridman (1:04:19.540)
accidental discovery, very important discovery,
Roger Penrose (1:04:22.340)
of this microwave background.
Lex Fridman (1:04:25.140)
And if you, there's the crackle on your television screen
Roger Penrose (1:04:28.460)
which is already sensing this microwave background,
Lex Fridman (1:04:32.740)
which is coming at us from all directions.
Lex Fridman (1:04:35.140)
And you can trace it back and back and back and back.
Lex Fridman (1:04:37.740)
And it came from a very early stage of the universe.
Roger Penrose (1:04:41.740)
Well, it's part of the Big Bang theory.
Lex Fridman (1:04:43.700)
The Big Bang theory was when people tried
Roger Penrose (1:04:45.660)
to solve Einstein's equations.
Lex Fridman (1:04:47.660)
They really found you had to have this initial state
Roger Penrose (1:04:50.780)
where the universe, it used to be called
Lex Fridman (1:04:52.420)
the primordial atom and things like this.
Roger Penrose (1:04:55.340)
There's Friedman and Lemaitre.
Lex Fridman (1:04:58.900)
Friedman was a Russian, Lemaitre was a Belgian.
Lex Fridman (1:05:01.420)
And they independently, well, basically Friedman first.
Lex Fridman (1:05:04.780)
And Lemaitre talked about the initial state,
Roger Penrose (1:05:08.860)
which is a very, very concentrated initial state
Lex Fridman (1:05:11.420)
which seemed to be the origin of the universe.
Roger Penrose (1:05:13.500)
Primordial atom.
Lex Fridman (1:05:14.820)
Primordial atom is what he called it, yes.
Lex Fridman (1:05:17.620)
And then it became, well, Fred Hoyle used the term
Lex Fridman (1:05:20.220)
Big Bang in a kind of derogatory sense.
Lex Fridman (1:05:22.540)
Just like with the Schrodinger and the cats, right?
Lex Fridman (1:05:25.140)
Yes, it's like sort of got picked up on
Roger Penrose (1:05:28.340)
whereas it wasn't his intention originally.
Lex Fridman (1:05:30.780)
But then the evidence piled up and piled up.
Lex Fridman (1:05:33.620)
And one of my friends and I learned a lot from him
Lex Fridman (1:05:36.460)
when I was in Cambridge was Dennis Sharma.
Roger Penrose (1:05:38.060)
He was a great proponent of steady state.
Lex Fridman (1:05:40.580)
And then he got converted.
Roger Penrose (1:05:41.980)
He said, no, I'm sorry.
Lex Fridman (1:05:43.420)
I had a great respect for him.
Roger Penrose (1:05:44.500)
He went around lecturing and said, I was wrong.
Lex Fridman (1:05:46.780)
The steady state model doesn't work.
Roger Penrose (1:05:48.900)
There was this Big Bang.
Lex Fridman (1:05:50.900)
And this microwave background that you see,
Roger Penrose (1:05:53.620)
okay, it's not actually quite the Big Bang.
Lex Fridman (1:05:55.380)
When I say not quite, it's about 380,000 years
Roger Penrose (1:05:58.660)
after the Big Bang, but that's what you see.
Lex Fridman (1:06:01.460)
But then you have to have had this Big Bang before it
Roger Penrose (1:06:03.780)
in order to make the equations work.
Lex Fridman (1:06:05.740)
And it works beautifully except for one little thing,
Roger Penrose (1:06:09.660)
which is this thing called inflation,
Lex Fridman (1:06:11.060)
which people had to put into it to make it work.
Roger Penrose (1:06:14.060)
When I first heard of it, I didn't like it at all.
Lex Fridman (1:06:16.860)
What's inflation?
Roger Penrose (1:06:17.940)
Inflation is that in the first,
Lex Fridman (1:06:20.380)
I'm gonna give you a very tiny number.
Roger Penrose (1:06:22.740)
Think of a second.
Lex Fridman (1:06:23.940)
That's not very long.
Roger Penrose (1:06:25.180)
Now I'm gonna give you a fraction of a second,
Lex Fridman (1:06:26.980)
one over a number.
Roger Penrose (1:06:29.460)
This number has 32 digits between,
Lex Fridman (1:06:34.340)
well, let's say between 36 and 32 digits.
Roger Penrose (1:06:37.740)
Tiny, tiny time between those two tiny,
Lex Fridman (1:06:41.260)
ridiculous seconds, fraction of a second,
Roger Penrose (1:06:44.500)
the universe was supposed to have expanded
Lex Fridman (1:06:46.580)
in this exponential way, an enormous way.
Roger Penrose (1:06:49.700)
For no apparent reason, you had to invent
Lex Fridman (1:06:52.060)
a particular thing called the inflaton field
Roger Penrose (1:06:54.700)
to make it do it.
Lex Fridman (1:06:56.060)
And I thought this is completely crazy.
Roger Penrose (1:06:58.180)
There are reasons why people stuck with this idea.
Lex Fridman (1:07:01.980)
You see, the thing is that I formed my model
Roger Penrose (1:07:04.180)
for reasons which are very fundamental, if you like.
Lex Fridman (1:07:07.700)
It has to do with this very fundamental principle,
Roger Penrose (1:07:10.420)
which is known as the second law of thermodynamics.
Lex Fridman (1:07:13.780)
The second law of thermodynamics says more or less,
Roger Penrose (1:07:16.100)
things get more and more random as time goes on.
Lex Fridman (1:07:20.020)
Now, another way of saying exactly the same thing
Roger Penrose (1:07:22.100)
is things get less and less random.
Lex Fridman (1:07:24.340)
As things go back, as you go back in time,
Roger Penrose (1:07:26.380)
they get less and less random.
Lex Fridman (1:07:28.060)
They go back and back and back and back.
Lex Fridman (1:07:30.100)
And the earliest thing you can directly see
Lex Fridman (1:07:32.020)
is this microwave background.
Roger Penrose (1:07:34.580)
What's one of the most striking features of it
Lex Fridman (1:07:37.540)
is that it's random.
Roger Penrose (1:07:39.220)
It has this, what you call this spectrum of,
Lex Fridman (1:07:43.700)
which is what's called the Planck spectrum,
Roger Penrose (1:07:46.060)
of frequencies, different intensities
Lex Fridman (1:07:48.740)
for different frequencies.
Lex Fridman (1:07:49.660)
And it's this wonderful curve due to Max Planck.
Lex Fridman (1:07:53.340)
And what's it telling you?
Roger Penrose (1:07:54.700)
It's telling you that the entropy is at a maximum.
Lex Fridman (1:07:58.020)
Started off at a maximum and it's going up ever since.
Roger Penrose (1:08:02.140)
I call that the mammoth in the room.
Lex Fridman (1:08:03.900)
I mean, it's a paradox.
Roger Penrose (1:08:05.580)
A mammoth, yeah, it is.
Lex Fridman (1:08:07.220)
And so people, why don't cosmologists worry about this?
Lex Fridman (1:08:10.500)
So I worried about it.
Lex Fridman (1:08:11.940)
And then I thought, well, it's not really a paradox
Roger Penrose (1:08:14.940)
because you're looking at matter and radiation
Lex Fridman (1:08:19.060)
at a maximum entropy state.
Lex Fridman (1:08:20.700)
What you're not seeing directly in that is the gravitation.
Lex Fridman (1:08:25.420)
It's gravitation, which is not thermalized.
Roger Penrose (1:08:28.460)
The gravitation was very, very low entropy.
Lex Fridman (1:08:32.020)
And it's low entropy by the uniformity.
Lex Fridman (1:08:34.500)
And you see that in the microwave too.
Lex Fridman (1:08:35.980)
It's very uniform over the whole sky.
Roger Penrose (1:08:38.260)
I'm compressing a long story
Lex Fridman (1:08:39.500)
into a very short few sentences.
Lex Fridman (1:08:40.820)
And doing a great job, yeah.
Lex Fridman (1:08:42.060)
So what I'm saying is that there's a huge puzzle.
Lex Fridman (1:08:45.780)
Why was gravity in this very low entropy state,
Lex Fridman (1:08:50.700)
very highly organized state, everything else was all random?
Lex Fridman (1:08:55.260)
And that to me was the biggest problem in cosmology.
Lex Fridman (1:08:59.060)
The biggest problem, nobody seems to even worry about it.
Roger Penrose (1:09:02.860)
People say they solved all the problems
Lex Fridman (1:09:04.540)
and they don't even worry about it.
Roger Penrose (1:09:05.620)
They think inflation solves it.
Lex Fridman (1:09:07.420)
It doesn't, it can't.
Roger Penrose (1:09:08.860)
Because it's just that...
Lex Fridman (1:09:12.260)
Just to clarify, that was your problem
Roger Penrose (1:09:14.660)
with the inflation describing some aspect
Lex Fridman (1:09:18.140)
of the moments right after the Big Bang?
Roger Penrose (1:09:20.540)
Inflation is supposed to stretch it out
Lex Fridman (1:09:22.220)
and make it all uniform, you see.
Roger Penrose (1:09:23.940)
It doesn't do it because it can only do it
Lex Fridman (1:09:25.420)
if it's uniform already at the beginning.
Roger Penrose (1:09:27.180)
It's, you just have to look at,
Lex Fridman (1:09:28.540)
I can't go into the details, but it doesn't solve it.
Lex Fridman (1:09:31.700)
And it was completely clear to me it doesn't solve it.
Lex Fridman (1:09:33.820)
But where does the conformal cyclic cosmology
Roger Penrose (1:09:36.340)
of starting to talk about something before
Lex Fridman (1:09:40.260)
that singular and the Big Bang?
Roger Penrose (1:09:41.820)
I was just thinking to myself,
Lex Fridman (1:09:44.220)
how boring this universe is going to be.
Roger Penrose (1:09:47.660)
You've got this exponential expansion.
Lex Fridman (1:09:49.500)
This was discovered early in the,
Roger Penrose (1:09:51.460)
in this century, 21st century.
Lex Fridman (1:09:56.740)
People discovered that these supernova exploding stars
Roger Penrose (1:10:01.060)
showed that the universe is actually undergoing
Lex Fridman (1:10:04.580)
this exponential expansion.
Lex Fridman (1:10:07.460)
So it's a self similar expansion.
Lex Fridman (1:10:10.580)
And it seems to be a feature of this term
Roger Penrose (1:10:14.260)
that Einstein introduced into his cosmology
Lex Fridman (1:10:17.140)
for the wrong reason.
Roger Penrose (1:10:18.540)
He wanted a universe that was static.
Lex Fridman (1:10:20.580)
He put this new term into his cosmology.
Roger Penrose (1:10:23.500)
To make it make sense,
Lex Fridman (1:10:24.420)
it's called the cosmological constant.
Lex Fridman (1:10:26.460)
And then when he got convinced
Lex Fridman (1:10:28.260)
that the universe had a Big Bang,
Roger Penrose (1:10:29.540)
he retracted it complaining this was his greatest blunder.
Lex Fridman (1:10:33.300)
The trouble is it wasn't a blunder.
Roger Penrose (1:10:34.660)
It was actually right, very ironic.
Lex Fridman (1:10:37.900)
And so the universe seems to be behaving
Roger Penrose (1:10:40.260)
with this cosmological constant.
Lex Fridman (1:10:41.980)
Okay, so this universe is expanding and expanding.
Lex Fridman (1:10:45.100)
What's going to happen in the future?
Lex Fridman (1:10:46.340)
Well, it gets more and more boring for a while.
Lex Fridman (1:10:48.860)
What's the most interesting thing in the universe?
Lex Fridman (1:10:50.580)
Well, there's black holes.
Roger Penrose (1:10:51.860)
The black holes more or less gulp down
Lex Fridman (1:10:53.660)
entire clusters of galaxies.
Roger Penrose (1:10:56.660)
The cluster, it'll swallow up most of our galaxy.
Lex Fridman (1:10:59.100)
We will run into our Andromeda galaxy's black hole.
Roger Penrose (1:11:01.460)
That black hole will swallow our one.
Lex Fridman (1:11:03.660)
They'll get bigger and bigger
Lex Fridman (1:11:04.700)
and they'll basically swallow up
Lex Fridman (1:11:07.100)
the whole cluster of galaxies, gulp it all down.
Roger Penrose (1:11:10.060)
Pretty well all, most of it, maybe not all, most of it.
Lex Fridman (1:11:13.780)
Okay, then that'll happen to,
Roger Penrose (1:11:15.300)
there'll be just these black holes around.
Lex Fridman (1:11:16.820)
Pretty boring, but still not as boring as it's gonna get.
Roger Penrose (1:11:19.620)
It's gonna get more boring because these black holes,
Lex Fridman (1:11:21.660)
you wait and you wait and you wait and you wait
Roger Penrose (1:11:24.060)
an unbelievable length of time
Lex Fridman (1:11:26.140)
and Hawking's black hole evaporation starts to come in.
Lex Fridman (1:11:30.300)
And the black holes, you just, it's incredibly tedious.
Lex Fridman (1:11:34.340)
Finally evaporate away.
Roger Penrose (1:11:36.340)
Each one goes away, disappears with a pop at the end.
Lex Fridman (1:11:39.700)
What could be more boring?
Roger Penrose (1:11:40.940)
It was boring then, now this is really boring.
Lex Fridman (1:11:43.820)
There's nothing, not even black holes.
Roger Penrose (1:11:46.620)
Universe gets colder and colder and colder and colder.
Lex Fridman (1:11:48.940)
And I thought, this is very, very boring.
Lex Fridman (1:11:52.460)
Now that's not science, is it?
Lex Fridman (1:11:54.540)
But it's emotional.
Lex Fridman (1:11:56.420)
So I thought, who's gonna be bored by this universe?
Lex Fridman (1:11:59.620)
Not us, we won't be around.
Roger Penrose (1:12:01.540)
It'll be mostly photons running around.
Lex Fridman (1:12:04.100)
And what the photons do, they don't get bored
Roger Penrose (1:12:06.180)
because it's part of relativity, you see.
Lex Fridman (1:12:08.780)
It's not really that they don't experience anything.
Roger Penrose (1:12:10.900)
That's not the point.
Lex Fridman (1:12:12.420)
Photons get right out to infinity
Roger Penrose (1:12:15.820)
without experience any time.
Lex Fridman (1:12:18.580)
It's the way relativity works.
Lex Fridman (1:12:21.020)
And this was part of what I used to do in my old days
Lex Fridman (1:12:23.500)
when I was looking at gravitational radiation
Lex Fridman (1:12:25.260)
and how things behaved to infinity.
Lex Fridman (1:12:27.500)
Infinity is just like another place.
Roger Penrose (1:12:30.060)
You can squash it down.
Lex Fridman (1:12:31.900)
As long as you don't have any mass in the world,
Roger Penrose (1:12:34.460)
infinity is just another place.
Lex Fridman (1:12:36.460)
The photons get there, the gravitons get there.
Lex Fridman (1:12:39.700)
What do they get?
Lex Fridman (1:12:40.540)
They've run into infinity.
Lex Fridman (1:12:42.100)
They say, well, now I'm here, what do I?
Lex Fridman (1:12:44.300)
There's something on the other side, is there?
Roger Penrose (1:12:46.660)
The usual view, it's just a mathematical notion.
Lex Fridman (1:12:48.620)
There's nothing on the other side.
Roger Penrose (1:12:49.620)
That's just the boundary of it.
Lex Fridman (1:12:51.740)
A nice example is this beautiful series of pictures
Roger Penrose (1:12:54.980)
by the Dutch artist MC Escher.
Lex Fridman (1:12:57.180)
You may know them.
Roger Penrose (1:12:58.020)
The one's called Circle Limits.
Lex Fridman (1:12:59.660)
They're a very famous one with the angels and the devils.
Lex Fridman (1:13:02.500)
And you can see them crowding and crowding
Lex Fridman (1:13:04.220)
and crowding up to the edge.
Roger Penrose (1:13:06.020)
Now, the kind of geometry that these angels and devils
Lex Fridman (1:13:09.060)
inhabit, that's their infinity.
Lex Fridman (1:13:12.380)
But from our perspective, infinity is just a place.
Lex Fridman (1:13:16.820)
Okay, there is...
Lex Fridman (1:13:17.660)
I'm sorry, can you just take a brief pause?
Lex Fridman (1:13:20.220)
Yes.
Roger Penrose (1:13:21.060)
In just the words you're saying,
Lex Fridman (1:13:22.860)
infinity is just a place.
Lex Fridman (1:13:24.100)
So for the most part, infinity, sort of even just going back,
Lex Fridman (1:13:28.820)
infinity is a mathematical concept.
Roger Penrose (1:13:31.220)
I think this is one of the things...
Lex Fridman (1:13:32.060)
You think there's an actual physical manifest...
Roger Penrose (1:13:35.500)
In which way does infinity ever manifest itself
Lex Fridman (1:13:38.420)
in our physical universe?
Roger Penrose (1:13:40.140)
Well, it does in various places.
Lex Fridman (1:13:41.820)
You see, it's a thing that if you're not a mathematician,
Roger Penrose (1:13:44.500)
you think, oh, infinity, I can't think about that.
Lex Fridman (1:13:46.500)
Mathematicians think about affinity all the time.
Roger Penrose (1:13:48.700)
They get used to the idea and they just play around
Lex Fridman (1:13:50.940)
with different kinds of infinities
Lex Fridman (1:13:52.340)
and it becomes no problem.
Lex Fridman (1:13:54.220)
But you just have to take my word for it.
Roger Penrose (1:13:57.260)
Now, one of the things is,
Lex Fridman (1:13:58.500)
you see, you take a Euclidean geometry.
Roger Penrose (1:14:00.820)
Well, it just keeps on going and it goes out to infinity.
Lex Fridman (1:14:04.660)
Now, there's other kinds of geometry
Lex Fridman (1:14:06.180)
and this is what's called hyperbolic geometry.
Lex Fridman (1:14:09.260)
It's a bit like Euclidean geometry,
Roger Penrose (1:14:10.820)
it's a little bit different.
Lex Fridman (1:14:12.140)
It's like what Escher was trying to describe
Roger Penrose (1:14:14.660)
in his angels and devils.
Lex Fridman (1:14:17.260)
And he learned about this from Coxeter
Lex Fridman (1:14:19.700)
and he think that's a very nice thing.
Lex Fridman (1:14:21.780)
That's why I represent this infinity
Roger Penrose (1:14:24.060)
to this kind of geometry.
Lex Fridman (1:14:25.820)
So it's not quite Euclidean geometry,
Roger Penrose (1:14:27.140)
it's a bit like it,
Lex Fridman (1:14:28.300)
that the angels and the devils inhabit.
Lex Fridman (1:14:30.900)
And their infinity, by this nice transformation,
Lex Fridman (1:14:34.180)
you squash their infinity down
Lex Fridman (1:14:36.820)
so you can draw it as this nice circle boundary
Lex Fridman (1:14:39.580)
to their universe.
Roger Penrose (1:14:42.220)
Now, from our outside perspective,
Lex Fridman (1:14:44.260)
we can see their infinity as this boundary.
Roger Penrose (1:14:47.420)
Now, what I'm saying is that it's very like that.
Lex Fridman (1:14:50.540)
The infinity that we might experience
Roger Penrose (1:14:53.540)
like those angels and devils in their world
Lex Fridman (1:14:56.180)
can be thought of as a boundary.
Roger Penrose (1:14:59.460)
Now, I found this a very useful way
Lex Fridman (1:15:01.940)
of talking about radiation,
Roger Penrose (1:15:03.940)
gravitational radiation and things like that.
Lex Fridman (1:15:07.100)
It was a trick, mathematical trick.
Lex Fridman (1:15:10.020)
So now what I'm saying is that
Lex Fridman (1:15:11.340)
that mathematical trick becomes real.
Roger Penrose (1:15:14.940)
That somehow, the photons,
Lex Fridman (1:15:17.860)
they need to go somewhere
Roger Penrose (1:15:19.980)
because from their perspective,
Lex Fridman (1:15:22.780)
infinity is just another place.
Roger Penrose (1:15:25.060)
Now, this is a difficult idea to get your mind around.
Lex Fridman (1:15:28.340)
So that's one of the reasons cosmologists
Roger Penrose (1:15:31.660)
are finding a lot of trouble taking me seriously.
Lex Fridman (1:15:34.820)
But to me, it's not such a wild idea.
Lex Fridman (1:15:37.540)
What's on the other side of that infinity?
Lex Fridman (1:15:39.780)
You have to think, why am I allowed to think of this?
Lex Fridman (1:15:43.060)
Why am I allowed to think of this?
Lex Fridman (1:15:45.340)
Because photons don't have any mass.
Lex Fridman (1:15:48.940)
And we in physics have beautiful ways of measuring time.
Lex Fridman (1:15:53.620)
There are incredibly precise clocks,
Roger Penrose (1:15:55.940)
atomic and nuclear clocks, unbelievably precise.
Lex Fridman (1:15:59.620)
Why are they so precise?
Roger Penrose (1:16:01.660)
Because of the two most famous equations
Lex Fridman (1:16:04.660)
of 20th century physics.
Roger Penrose (1:16:06.820)
One of them is Einstein's E equals MC squared.
Lex Fridman (1:16:10.060)
What's that tell us?
Roger Penrose (1:16:11.100)
Energy and mass are equivalent.
Lex Fridman (1:16:14.900)
The other one is even older than that,
Roger Penrose (1:16:16.660)
still 20th century, only just.
Lex Fridman (1:16:18.540)
Max Planck, E equals h nu.
Roger Penrose (1:16:22.660)
Nu is a frequency,
Lex Fridman (1:16:24.420)
h is a constant, again, like C.
Roger Penrose (1:16:26.460)
E is energy.
Lex Fridman (1:16:28.020)
Energy and frequency are equivalent.
Roger Penrose (1:16:31.620)
Put the two together,
Lex Fridman (1:16:33.060)
energy and mass are equivalent, Einstein.
Roger Penrose (1:16:34.980)
Energy and frequency are equivalent, Max Planck.
Lex Fridman (1:16:37.340)
Put the two together, mass and frequency are equivalent.
Roger Penrose (1:16:41.420)
Absolutely basic physical principle.
Lex Fridman (1:16:44.100)
If you have a massive entity, a massive particle,
Roger Penrose (1:16:47.500)
it is a clock with a very, very precise frequency.
Lex Fridman (1:16:53.460)
It's not, you can't directly use it,
Roger Penrose (1:16:55.020)
you have to scale it down.
Lex Fridman (1:16:56.140)
So your atomic and nuclear clocks,
Lex Fridman (1:16:57.660)
but that's the basic principle.
Lex Fridman (1:16:59.180)
You scale it down to something you can actually perceive.
Lex Fridman (1:17:02.260)
But it's the same principle.
Lex Fridman (1:17:03.860)
If you have mass, you have beautiful clocks.
Lex Fridman (1:17:07.900)
But the other side of that coin is,
Lex Fridman (1:17:10.340)
if you don't have mass, you don't have clocks.
Roger Penrose (1:17:14.820)
If you don't have clocks, you don't have rulers.
Lex Fridman (1:17:18.060)
You don't have scale.
Lex Fridman (1:17:20.180)
So you don't have space and time.
Lex Fridman (1:17:21.380)
You don't have a measure of the scale of space and time.
Roger Penrose (1:17:24.820)
Oh, scale of space and time.
Lex Fridman (1:17:26.500)
You do have the structure,
Roger Penrose (1:17:29.180)
what's called the conformal structure.
Lex Fridman (1:17:30.860)
You see, it's what the angels and devils have.
Roger Penrose (1:17:33.100)
If you look at the eye of the devil,
Lex Fridman (1:17:35.060)
no matter how close to the boundary it is,
Roger Penrose (1:17:36.900)
it has the same shape, but it has a different size.
Lex Fridman (1:17:40.820)
So you can scale up and you can scale down,
Lex Fridman (1:17:43.380)
but you mustn't change the shape.
Lex Fridman (1:17:46.420)
So it's basically the same idea,
Lex Fridman (1:17:48.540)
but applied to space time now.
Lex Fridman (1:17:50.780)
In the very remote future,
Roger Penrose (1:17:52.620)
you have things which don't measure the scale,
Lex Fridman (1:17:55.700)
but the shape, if you like, is still there.
Roger Penrose (1:17:58.460)
Now that's in the remote future.
Lex Fridman (1:17:59.940)
Now I'm gonna do the exact opposite.
Roger Penrose (1:18:01.980)
Now I'm gonna go way back into the Big Bang.
Lex Fridman (1:18:04.660)
Now as you get there, things get hotter and hotter,
Roger Penrose (1:18:08.100)
denser and denser.
Lex Fridman (1:18:10.660)
What's the universe dominated by?
Roger Penrose (1:18:13.020)
Particles moving around almost with the speed of light.
Lex Fridman (1:18:16.580)
When they get almost with the speed of light,
Roger Penrose (1:18:19.060)
okay, they begin to lose the mass too.
Lex Fridman (1:18:21.820)
So for completely opposite reason,
Roger Penrose (1:18:24.260)
they lose the sense of scale as well.
Lex Fridman (1:18:26.900)
So my crazy idea is the Big Bang and the remote future,
Roger Penrose (1:18:32.260)
they seem completely different.
Lex Fridman (1:18:33.500)
One is extremely dense, extremely hot.
Roger Penrose (1:18:36.140)
The other is very, very rarefied and very, very cold.
Lex Fridman (1:18:39.820)
But if you squash one down by this conformal scaling,
Roger Penrose (1:18:42.860)
you get the other.
Lex Fridman (1:18:44.340)
So although they look and feel very different,
Roger Penrose (1:18:48.020)
they're really almost the same.
Lex Fridman (1:18:50.460)
The remote future on the other side,
Lex Fridman (1:18:53.180)
I'm claiming is that where do the photons go?
Lex Fridman (1:18:55.620)
They go into the next Big Bang.
Roger Penrose (1:18:58.740)
You've got to get your mind around that crazy idea.
Lex Fridman (1:19:01.260)
Taking a step on the other side of the place
Roger Penrose (1:19:03.820)
that is infinity.
Lex Fridman (1:19:05.660)
Okay, but.
Lex Fridman (1:19:07.260)
So I'm saying the other side of our Big Bang,
Lex Fridman (1:19:09.100)
now I'm going back into the Big Bang.
Roger Penrose (1:19:10.620)
Back, backwards.
Lex Fridman (1:19:11.460)
There was the remote future of a previous eon.
Roger Penrose (1:19:13.820)
Previous eon.
Lex Fridman (1:19:15.140)
And what I'm saying is that previous eon,
Roger Penrose (1:19:17.620)
there are signals coming through to us,
Lex Fridman (1:19:20.300)
which we can see and which we do see.
Lex Fridman (1:19:23.860)
And these are both signals,
Lex Fridman (1:19:25.180)
the two main signals are to do with black holes.
Roger Penrose (1:19:29.540)
One of them is the collisions between black holes.
Lex Fridman (1:19:33.140)
And as they spiral into each other,
Roger Penrose (1:19:35.300)
they release a lot of energy
Lex Fridman (1:19:37.060)
in the form of gravitational waves.
Roger Penrose (1:19:39.220)
Those gravitational waves get through
Lex Fridman (1:19:42.300)
in a certain form into the next eon.
Roger Penrose (1:19:44.260)
That's fascinating that there's some,
Lex Fridman (1:19:46.340)
I mean, maybe you can correct me if I'm wrong,
Lex Fridman (1:19:49.140)
but that means that some information can travel
Lex Fridman (1:19:52.100)
from another eon.
Roger Penrose (1:19:53.420)
Exactly.
Lex Fridman (1:19:54.340)
That is fascinating.
Roger Penrose (1:19:58.860)
I mean, I've seen somewhere described
Lex Fridman (1:20:01.700)
sort of the discussion of the Fermi Paradox,
Roger Penrose (1:20:05.340)
you know, that if there's intelligent life.
Lex Fridman (1:20:08.260)
Yes.
Roger Penrose (1:20:09.100)
Being, you know, communication immediately takes you there.
Lex Fridman (1:20:12.140)
So.
Roger Penrose (1:20:13.180)
We have a paper, I have my colleague,
Lex Fridman (1:20:16.020)
Vahid Guzajan, who I worked with on these ideas for a while.
Roger Penrose (1:20:19.820)
We have a crazy paper on that, yes.
Lex Fridman (1:20:21.740)
So.
Roger Penrose (1:20:22.580)
Looking at the Fermi Paradox, yes.
Lex Fridman (1:20:23.540)
Right, so if the universe is just cycling
Roger Penrose (1:20:25.980)
over and over and over,
Lex Fridman (1:20:27.260)
punctuated by the, punctuated the singularity
Roger Penrose (1:20:31.660)
of the Big Bang,
Lex Fridman (1:20:32.780)
and then intelligent or any kind of intelligent systems
Roger Penrose (1:20:36.780)
can communicate through from eon to eon,
Lex Fridman (1:20:39.580)
why haven't we heard anything from our alien friends?
Roger Penrose (1:20:44.700)
Because we don't know how to look.
Lex Fridman (1:20:46.980)
That's fundamentally the reason, is we.
Roger Penrose (1:20:48.900)
I don't know, you see, it's speculation.
Lex Fridman (1:20:51.820)
I mean, the SETI program is a reasonable thing to do,
Lex Fridman (1:20:55.460)
but still speculation.
Lex Fridman (1:20:56.940)
It's trying to say, okay, maybe not too far away
Roger Penrose (1:21:01.860)
was a civilization which got there first, before us,
Lex Fridman (1:21:05.620)
early enough that they could send us signals,
Lex Fridman (1:21:08.740)
but how far away would you need to go before,
Lex Fridman (1:21:11.060)
I mean, I don't know, we have so little knowledge
Roger Penrose (1:21:13.340)
about that, we haven't seen any signals yet,
Lex Fridman (1:21:15.820)
but it's worth looking, it's worth looking.
Lex Fridman (1:21:18.260)
What I'm trying to say, here's another possible place
Lex Fridman (1:21:21.380)
where you might look.
Roger Penrose (1:21:22.580)
Now you're not looking at civilizations
Lex Fridman (1:21:24.620)
which got there first,
Roger Penrose (1:21:26.220)
you're looking at those civilizations
Lex Fridman (1:21:27.980)
which were so successful,
Roger Penrose (1:21:29.180)
probably a lot more successful than they're likely to be
Lex Fridman (1:21:32.420)
by the looks of things,
Roger Penrose (1:21:34.900)
which knew how to handle their own global warming
Lex Fridman (1:21:38.100)
or whatever it is and to get through it all
Lex Fridman (1:21:40.460)
and to live to a ripe old age in the sense of a civilization
Lex Fridman (1:21:45.460)
to the extent that they could harness signals
Roger Penrose (1:21:49.180)
that they could propagate through for some reason
Lex Fridman (1:21:52.340)
of their own desires, whatever we wouldn't know
Roger Penrose (1:21:55.700)
to other civilizations
Lex Fridman (1:21:57.780)
which might be able to pick up the signals.
Lex Fridman (1:22:00.180)
But what kind of signals would they be?
Lex Fridman (1:22:01.980)
I haven't the foggiest.
Roger Penrose (1:22:05.180)
Let me ask the question.
Lex Fridman (1:22:06.460)
Yes.
Lex Fridman (1:22:07.300)
What to you is the most beautiful idea
Lex Fridman (1:22:09.060)
in physics or mathematics or the art
Lex Fridman (1:22:12.620)
at the intersection of the two?
Lex Fridman (1:22:15.100)
I'm gonna have to say complex analysis.
Roger Penrose (1:22:17.180)
I might've said infinities.
Lex Fridman (1:22:19.620)
And one of the most single, most beautiful idea
Roger Penrose (1:22:22.620)
I think was the fact that you can have
Lex Fridman (1:22:24.460)
infinities of different sizes and so on.
Lex Fridman (1:22:26.860)
But that's in a way, I think complex analysis.
Lex Fridman (1:22:30.380)
It's got so much magic in it.
Roger Penrose (1:22:32.940)
It's a very simple idea.
Lex Fridman (1:22:36.020)
You take these, you take numbers,
Roger Penrose (1:22:39.460)
you take the integers and then you fill them up
Lex Fridman (1:22:41.820)
into the fractions and the real numbers.
Roger Penrose (1:22:44.180)
You imagine you're trying to measure a continuous line
Lex Fridman (1:22:46.780)
and then you think of how you can solve equations.
Lex Fridman (1:22:50.420)
Then what about X squared equals minus one?
Lex Fridman (1:22:54.460)
Well, there's no real number which has to satisfy that.
Lex Fridman (1:22:57.460)
So you have to think of, well, there's a number called I.
Lex Fridman (1:23:01.340)
You think you invent it.
Roger Penrose (1:23:02.340)
Well, in a certain sense, it's there already.
Lex Fridman (1:23:05.180)
But this number, when you add that square root
Roger Penrose (1:23:07.460)
of minus one to it,
Lex Fridman (1:23:08.300)
you have what's called the complex numbers.
Lex Fridman (1:23:10.940)
And they're an incredible system.
Lex Fridman (1:23:13.860)
If you like, you put one little thing in,
Roger Penrose (1:23:15.700)
you put square root of minus one in
Lex Fridman (1:23:17.340)
and you get how much benefit out of it.
Roger Penrose (1:23:20.620)
All sorts of things that you'd never imagined before.
Lex Fridman (1:23:23.420)
And it's that amazing, all hiding there
Roger Penrose (1:23:27.740)
in putting that square root of minus one in.
Lex Fridman (1:23:30.140)
I think that's the most magical thing I've seen
Roger Penrose (1:23:32.660)
in mathematics or physics.
Lex Fridman (1:23:34.020)
And it's in quantum mechanics.
Lex Fridman (1:23:35.580)
And in quantum mechanics.
Lex Fridman (1:23:36.420)
You see, it's there already.
Lex Fridman (1:23:38.220)
You might think, what's it doing there?
Lex Fridman (1:23:39.700)
Okay, just a nice beautiful piece of mathematics.
Lex Fridman (1:23:41.660)
And then suddenly we see, nope.
Lex Fridman (1:23:44.180)
It's the very crucial basis of quantum mechanics.
Roger Penrose (1:23:47.220)
It's there and the way the world works.
Lex Fridman (1:23:49.540)
So on the question of whether math
Roger Penrose (1:23:50.980)
is discovered or invented,
Lex Fridman (1:23:52.820)
it sounds like you may be suggesting
Roger Penrose (1:23:54.620)
that partially it's possible
Lex Fridman (1:23:56.180)
that math is indeed discovered.
Roger Penrose (1:23:57.860)
Oh, absolutely, yes.
Lex Fridman (1:23:59.660)
No, it's more like archeology than you might think.
Roger Penrose (1:24:02.180)
Yes, yes.
Lex Fridman (1:24:03.900)
So let me ask the most ridiculous,
Roger Penrose (1:24:06.580)
maybe the most important question.
Lex Fridman (1:24:08.660)
What is the meaning of life?
Lex Fridman (1:24:11.580)
What gives your life fulfillment, purpose,
Lex Fridman (1:24:15.060)
happiness, and meaning?
Lex Fridman (1:24:16.020)
Why do you think we're here on this?
Lex Fridman (1:24:18.260)
Given all the big bang and the infinities of photons
Roger Penrose (1:24:20.980)
that we've talked about.
Lex Fridman (1:24:21.820)
All I would say, I think it's not a stupid question.
Roger Penrose (1:24:26.620)
I mean, there are some people, you know,
Lex Fridman (1:24:28.180)
many of my colleagues who are scientists,
Lex Fridman (1:24:29.780)
and they say, well, that's a stupid question,
Lex Fridman (1:24:31.340)
meaning, yeah, well, we're just here
Roger Penrose (1:24:32.540)
because things came together and produced life
Lex Fridman (1:24:35.420)
and so what.
Roger Penrose (1:24:37.660)
I think there's more to it.
Lex Fridman (1:24:39.260)
But what there is that's more to it,
Roger Penrose (1:24:41.100)
I have really much idea.
Lex Fridman (1:24:43.140)
And it might be somehow connected
Roger Penrose (1:24:44.420)
to the mechanisms of consciousness
Lex Fridman (1:24:46.300)
that we've been talking about, the mystery there.
Roger Penrose (1:24:49.540)
It's connected with all sorts of, yeah,
Lex Fridman (1:24:51.060)
I think these things are tied up in ways which are,
Roger Penrose (1:24:54.900)
you see, I tend to think the mystery of consciousness
Lex Fridman (1:24:56.780)
is tied up with the mystery of quantum mechanics
Lex Fridman (1:25:00.980)
and how it fits in with the classical world,
Lex Fridman (1:25:04.020)
and that's all to do with the mystery of complex numbers.
Lex Fridman (1:25:08.500)
And there are mysteries there
Lex Fridman (1:25:10.700)
which look like mathematical mysteries,
Lex Fridman (1:25:13.060)
but they seem to have a bearing
Lex Fridman (1:25:15.740)
on the way the physical world operates.
Roger Penrose (1:25:18.700)
We're scratching the surface.
Lex Fridman (1:25:20.780)
We have a long, huge way to go
Roger Penrose (1:25:22.980)
before we really understand that.
Lex Fridman (1:25:24.820)
And it's a beautiful idea that the depth,
Roger Penrose (1:25:28.340)
the mathematical depth could be discovered,
Lex Fridman (1:25:30.700)
and then there's tragedies of ghettos
Lex Fridman (1:25:32.940)
and completeness along the way
Lex Fridman (1:25:34.460)
that we'll have to somehow figure our ways around.
Roger Penrose (1:25:37.540)
Yeah.
Lex Fridman (1:25:38.900)
So, Roger, it was a huge honor to talk to you.
Roger Penrose (1:25:42.100)
Thank you so much for your time today.
Lex Fridman (1:25:43.500)
It's been my pleasure.
Roger Penrose (1:25:44.540)
Thank you.
Lex Fridman (1:25:46.100)
Thanks for listening to this conversation
Roger Penrose (1:25:47.620)
with Roger Penrose,
Lex Fridman (1:25:48.980)
and thank you to our presenting sponsor, Cash App.
Roger Penrose (1:25:52.020)
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Lex Fridman (1:25:53.940)
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Lex Fridman (1:25:59.020)
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Lex Fridman (1:26:03.940)
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Roger Penrose (1:26:06.460)
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Lex Fridman (1:26:09.060)
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Roger Penrose (1:26:10.460)
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Lex Fridman (1:26:14.980)
And now let me leave you with some words of wisdom
Roger Penrose (1:26:17.020)
that Roger Penrose wrote in his book,
Lex Fridman (1:26:19.340)
The Emperor's New Mind.
Roger Penrose (1:26:21.660)
Beneath all this technicality is the feeling
Lex Fridman (1:26:24.460)
that it is indeed, quote unquote, obvious
Roger Penrose (1:26:28.060)
that the conscious mind cannot work like a computer,
Lex Fridman (1:26:31.220)
even though much of what is involved
Roger Penrose (1:26:33.060)
in mental activity might do so.
Lex Fridman (1:26:35.460)
This is the kind of obviousness that a child can see,
Roger Penrose (1:26:39.580)
though the child may later in life become browbeaten
Lex Fridman (1:26:42.740)
into believing that the obvious problems
Roger Penrose (1:26:44.820)
are quote unquote, non problems,
Lex Fridman (1:26:47.260)
to be argued into nonexistence by careful reasoning
Lex Fridman (1:26:51.060)
and clever choices of definition.
Lex Fridman (1:26:53.820)
Children sometimes see things clearly
Roger Penrose (1:26:56.540)
that are obscured in later life.
Lex Fridman (1:26:59.100)
We often forget the wonder that we felt as children
Roger Penrose (1:27:02.460)
when the cares of the quote unquote, real world
Lex Fridman (1:27:05.300)
had begun to settle on our shoulders.
Roger Penrose (1:27:07.860)
Children are not afraid to pose basic questions
Lex Fridman (1:27:10.540)
that may embarrass us as adults to ask.
Lex Fridman (1:27:13.620)
What happens to each of our streams of consciousness
Lex Fridman (1:27:15.740)
after we die?
Lex Fridman (1:27:17.220)
Where was it before we were born?
Lex Fridman (1:27:19.580)
Might we become or have been someone else?
Lex Fridman (1:27:23.220)
Why do we perceive it all?
Lex Fridman (1:27:25.180)
Why are we here?
Lex Fridman (1:27:26.900)
Why is there a universe here at all
Lex Fridman (1:27:28.620)
in which we can actually be?
Roger Penrose (1:27:30.900)
These are puzzles that tend to come
Lex Fridman (1:27:32.660)
with the awakenings of awareness in any of us
Lex Fridman (1:27:35.980)
and no doubt with the awakening of self awareness
Lex Fridman (1:27:39.980)
within whichever creature or other entity it first came.
Roger Penrose (1:27:43.700)
Thank you for listening and hope to see you next time.
Lex Fridman (20:01.140)
that he gave to a mathematical,
Roger Penrose (20:02.900)
I think it may be the Adams Society,
Lex Fridman (20:04.340)
one of the mathematical undergraduate societies.
Lex Fridman (20:07.140)
And he made this point again very clearly.
Lex Fridman (20:09.460)
That if you've got a formal system of proof,
Lex Fridman (20:11.780)
so suppose what you mean by proof
Lex Fridman (20:15.160)
is something which you could check with a computer.
Lex Fridman (20:19.140)
So to say whether you've got it right or not,
Lex Fridman (20:21.220)
you've got a lot of steps.
Lex Fridman (20:22.340)
Have you carried this computational procedure?
Lex Fridman (20:25.940)
Well, following the proof, steps of the proof correctly,
Roger Penrose (20:30.520)
that can be checked by an algorithm, by a computer.
Lex Fridman (20:35.420)
So that's the key thing.
Lex Fridman (20:38.780)
Now what you have to, now you see, is this any good?
Lex Fridman (20:44.420)
If you've got an algorithmic system,
Roger Penrose (20:47.260)
which claims to say, yes, this is right,
Lex Fridman (20:49.940)
this you've proved it correctly, this is true.
Roger Penrose (20:52.620)
If you've proved it, if you made a mistake,
Lex Fridman (20:54.820)
it doesn't say it's true or false.
Lex Fridman (20:55.980)
But if you have, if you've done it right,
Lex Fridman (20:57.940)
then the conclusion you've come to is correct.
Lex Fridman (21:01.980)
Now you say, why do you believe it's correct?
Lex Fridman (21:03.900)
Because you've looked at the rules and you said,
Roger Penrose (21:05.420)
well, okay, that one's all right.
Lex Fridman (21:06.720)
Yeah, that one's all right.
Lex Fridman (21:07.560)
What about that?
Lex Fridman (21:08.380)
Oh, yeah, I see, I see why it's all right.
Roger Penrose (21:10.100)
Okay, you go through all the rules.
Lex Fridman (21:12.020)
You say, yes, following those rules,
Roger Penrose (21:13.840)
if it says, yes, it's true, it is true.
Lex Fridman (21:17.860)
So you've got to make sure that these rules
Roger Penrose (21:19.940)
are ones that you trust.
Lex Fridman (21:21.980)
If you follow the rules and it says it's a proof,
Lex Fridman (21:25.020)
is the result actually true?
Lex Fridman (21:27.060)
Right.
Lex Fridman (21:27.900)
And that your belief that it's true
Lex Fridman (21:29.660)
depends upon looking at the rules and understanding them.
Roger Penrose (21:33.140)
Now, what Gödel shows, that if you have such a system,
Lex Fridman (21:38.180)
then you can construct a statement of the very kind
Roger Penrose (21:41.220)
that it's supposed to look at, a mathematical statement,
Lex Fridman (21:44.380)
and you can see by the way it's constructed
Lex Fridman (21:47.660)
and what it means that it's true,
Lex Fridman (21:52.380)
but not provable by the rules that you've been given.
Lex Fridman (21:56.620)
And it depends on your trust in the rules.
Lex Fridman (21:59.660)
Do you believe that the rules only give you truths?
Roger Penrose (22:02.300)
If you believe the rules only give you truths,
Lex Fridman (22:04.260)
then you believe this other statement is also true.
Roger Penrose (22:07.620)
I found this absolutely mind blowing.
Lex Fridman (22:09.900)
When I saw this, it blew my mind.
Roger Penrose (22:12.660)
I thought, my God, you can see that this statement is true.
Lex Fridman (22:17.060)
It's as good as any proof,
Roger Penrose (22:18.940)
because it only depends on your belief
Lex Fridman (22:21.860)
in the reliability of the proof procedure, that's all it is,
Lex Fridman (22:25.700)
and understanding that the coding is done correctly.
Lex Fridman (22:29.260)
And it enables you to transcend that system.
Lex Fridman (22:33.820)
So whatever system you have,
Lex Fridman (22:36.260)
as long as you can understand what it's doing
Lex Fridman (22:39.020)
and why you believe it only gives you truths,
Lex Fridman (22:41.980)
then you can see beyond that system.
Lex Fridman (22:44.700)
Now, how do you see beyond it?
Lex Fridman (22:46.220)
What is it that enables you to transcend that system?
Roger Penrose (22:51.740)
Well, it's your understanding
Lex Fridman (22:53.260)
of what the system is actually saying
Lex Fridman (22:55.740)
and what the statement that you've constructed
Lex Fridman (22:57.620)
is actually saying.
Lex Fridman (22:59.460)
So it's this quality of understanding, whatever it is,
Lex Fridman (23:03.140)
which is not governed by rules.
Roger Penrose (23:05.540)
It's not a computational procedure.
Lex Fridman (23:07.420)
So this idea of understanding is not going to be
Roger Penrose (23:09.660)
within the rules of the, within the formal system.
Lex Fridman (23:13.420)
Yes, you're only using those rules anyway,
Roger Penrose (23:15.940)
because you have understood them to be rules
Lex Fridman (23:18.340)
which only give you truths.
Roger Penrose (23:20.260)
There'd be no point in it otherwise.
Lex Fridman (23:22.260)
I mean, people say, well, okay, this is,
Roger Penrose (23:24.300)
it's one set of rules as good as any other.
Lex Fridman (23:28.020)
Well, it's not true.
Roger Penrose (23:28.860)
You see, you have to understand what the rules mean.
Lex Fridman (23:31.580)
And why does that understanding of the mean
Lex Fridman (23:33.580)
give you something beyond the rules themselves?
Lex Fridman (23:36.340)
And that's what it was.
Roger Penrose (23:37.340)
That's what blew my mind.
Lex Fridman (23:38.620)
It's somehow understanding why the rules give you truths
Roger Penrose (23:43.820)
enables you to transcend the rules.
Lex Fridman (23:45.900)
So that's where, I mean, even at that time,
Roger Penrose (23:48.060)
that's already where the thought entered your mind
Lex Fridman (23:50.900)
that the idea of understanding, or we can start calling it
Roger Penrose (23:55.340)
things like intelligence or even consciousness
Lex Fridman (23:57.980)
is outside the rules.
Roger Penrose (23:59.660)
Yes.
Lex Fridman (24:00.500)
See, I've always concentrated on understanding.
Roger Penrose (24:02.900)
You know, people say, people come and point out things.
Lex Fridman (24:05.300)
Well, you know, what about creativity?
Roger Penrose (24:07.140)
That's something a machine can't do is create.
Lex Fridman (24:09.100)
Well, I don't know.
Lex Fridman (24:09.940)
What is creativity?
Lex Fridman (24:11.260)
And I don't know.
Roger Penrose (24:12.100)
You know, somebody can put some funny things
Lex Fridman (24:13.860)
on a piece of paper and say that's creative
Lex Fridman (24:15.620)
and you could make a machine do that.
Lex Fridman (24:16.900)
Is it really creative?
Roger Penrose (24:18.100)
I don't know.
Lex Fridman (24:18.940)
You see, I worry about that one.
Roger Penrose (24:20.540)
I sort of agree with it in a sense,
Lex Fridman (24:22.860)
but it's so hard to do anything with that statement.
Lex Fridman (24:25.460)
But understanding, yes, you can.
Lex Fridman (24:27.740)
You can make, go see that understanding, whatever it is,
Lex Fridman (24:32.580)
and it's very hard to put your finger on it.
Lex Fridman (24:34.300)
That's absolutely true.
Lex Fridman (24:35.740)
Can you try to define or maybe dance around
Lex Fridman (24:39.620)
a definition of understanding?
Roger Penrose (24:41.980)
To some degree, but I don't, I often wondered about this,
Lex Fridman (24:45.980)
but there is something there which is very slippery.
Roger Penrose (24:48.900)
It's something like standing back.
Lex Fridman (24:52.700)
And it's got to be something, you see,
Roger Penrose (24:54.140)
it's also got to be something which was of value
Lex Fridman (24:56.940)
to our remote ancestors.
Roger Penrose (24:58.900)
Right.
Lex Fridman (24:59.740)
Because sometimes, there's a cartoon
Roger Penrose (25:01.540)
which I drew sometimes showing you how all these,
Lex Fridman (25:04.940)
there's in the foreground, you see this mathematician
Roger Penrose (25:07.140)
just doing some mathematical theorem.
Lex Fridman (25:08.860)
There's a little bit of a joke in that theorem,
Lex Fridman (25:10.500)
but let's not go into that.
Lex Fridman (25:12.300)
He's trying to prove some theorem.
Lex Fridman (25:14.420)
And he's about to be eaten by a saber tooth tiger
Lex Fridman (25:17.820)
who's hiding in the undergrowth, you see.
Lex Fridman (25:21.260)
And in the distance, you see his cousins
Lex Fridman (25:24.340)
building, growing crops, building shelters,
Roger Penrose (25:29.100)
domesticating animals, and in the slight foreground,
Lex Fridman (25:31.980)
you see they've built a mammoth trap
Lex Fridman (25:33.340)
and this poor old mammoth is falling into a pit, you see,
Lex Fridman (25:36.660)
and all these people around them are about to grab him,
Roger Penrose (25:39.540)
you see, and well, you see, those are the ones who,
Lex Fridman (25:43.380)
the quality of understanding, which goes with all,
Roger Penrose (25:47.300)
it's not just the mathematician doing his mathematics,
Lex Fridman (25:50.740)
this understanding quality is something else,
Roger Penrose (25:53.660)
which has been a tremendous advantage to us,
Lex Fridman (25:58.100)
not just to us.
Roger Penrose (25:59.660)
See, I don't think consciousness is limited to humans.
Lex Fridman (26:03.700)
Yeah, that's the interesting question,
Roger Penrose (26:04.900)
at which point, if it is indeed connected
Lex Fridman (26:07.380)
to the evolutionary process,
Lex Fridman (26:09.140)
at which point did we pick up this?
Lex Fridman (26:11.420)
A very hard question.
Roger Penrose (26:13.420)
It's certainly, I don't think it's primates,
Lex Fridman (26:15.860)
you know, you see these pictures of African hunting dogs
Lex Fridman (26:20.380)
and how they can plan amongst themselves
Lex Fridman (26:22.780)
how to catch the antelopes.
Roger Penrose (26:25.700)
Some of these David Attenborough films,
Lex Fridman (26:27.540)
I think this probably was one of them,
Lex Fridman (26:29.180)
and you could see the hunting dogs,
Lex Fridman (26:31.740)
and they divide themselves into two groups
Lex Fridman (26:34.300)
and they go in two routes, two different routes.
Lex Fridman (26:36.820)
One of them goes and they sort of hide next to the river.
Lex Fridman (26:40.700)
And the other group goes around
Lex Fridman (26:42.420)
and they start yelping at these, they don't bark,
Roger Penrose (26:46.460)
I guess whatever noise hunting dogs do,
Lex Fridman (26:48.980)
the antelopes, and they sort of round them up
Lex Fridman (26:51.020)
and they chase them in the direction of the river.
Lex Fridman (26:54.500)
And there are the other ones just waiting for them,
Roger Penrose (26:56.580)
just to get, because when they get to the river,
Lex Fridman (26:58.900)
it slows them down.
Lex Fridman (27:00.300)
And so they pounce on them.
Lex Fridman (27:02.060)
So they've obviously planned this all out somehow.
Roger Penrose (27:05.460)
I have no idea how.
Lex Fridman (27:07.660)
And there is some element of conscious planning,
Roger Penrose (27:11.460)
as far as I can see.
Lex Fridman (27:12.300)
I don't think it's just some kind of,
Lex Fridman (27:16.140)
so much of AI these days is done on what they call
Lex Fridman (27:19.580)
bottom up systems, is it?
Roger Penrose (27:21.060)
Yeah, where you have neural networks
Lex Fridman (27:23.660)
and you give them a zillion different things to look at
Lex Fridman (27:27.460)
and then they sort of can choose one thing over another,
Lex Fridman (27:33.780)
just because it's seen so many examples
Lex Fridman (27:35.460)
and picks up on little signals,
Lex Fridman (27:38.380)
which one may not even be conscious of.
Lex Fridman (27:41.540)
And that doesn't feel like understanding.
Lex Fridman (27:43.140)
There's no understanding in that whatsoever.
Roger Penrose (27:46.100)
Well, you're being a little bit human centric, so.
Lex Fridman (27:49.460)
Well, I'm talking about, I'm not with the dogs, am I?
Roger Penrose (27:52.860)
No, you're not.
Lex Fridman (27:53.700)
Sorry, not human centric, but I misspoke.
Roger Penrose (27:56.740)
Biology centric.
Lex Fridman (27:59.340)
Is it possible that consciousness
Lex Fridman (28:00.940)
would just look slightly different?
Lex Fridman (28:03.220)
Well, I'm not saying it's biological,
Roger Penrose (28:04.700)
because we don't know.
Lex Fridman (28:06.620)
I think other examples of elephants
Roger Penrose (28:08.500)
is a wonderful example, too.
Lex Fridman (28:10.660)
Where they, this was, I think this was an Attenborough one,
Roger Penrose (28:13.980)
where the elephants have to go from along,
Lex Fridman (28:17.220)
the troop of them have to go long distances.
Lex Fridman (28:20.100)
And the leader of a troop is a female.
Lex Fridman (28:21.620)
They all are, apparently.
Lex Fridman (28:23.500)
And this female, she had to go all the way
Lex Fridman (28:26.820)
from one part of the country to another.
Lex Fridman (28:30.100)
And at a certain point, she made a detour.
Lex Fridman (28:32.460)
And they went off in this big detour.
Roger Penrose (28:35.020)
All the troop came with her.
Lex Fridman (28:37.100)
And this was where her sister had died.
Lex Fridman (28:39.580)
And there were her bones lying around.
Lex Fridman (28:41.540)
And they're going to pick up the bones,
Lex Fridman (28:42.820)
and they hand it around, and they caress the bones.
Lex Fridman (28:45.780)
And then they put them back, and they go back again.
Lex Fridman (28:48.580)
What in the hell are they doing?
Lex Fridman (28:51.300)
That's so interesting.
Roger Penrose (28:52.260)
I mean, there's something going on.
Lex Fridman (28:54.540)
There's no clear connection with natural selection.
Roger Penrose (28:59.500)
There's just some deep feeling going on there,
Lex Fridman (29:03.060)
which has to do with their conscious experience.
Lex Fridman (29:06.980)
And I think it's something that, overall,
Lex Fridman (29:09.940)
is advantageous, our natural selection,
Lex Fridman (29:15.020)
but not directly to do with natural selection.
Lex Fridman (29:18.740)
I like that.
Roger Penrose (29:19.580)
There's something going on there.
Lex Fridman (29:22.540)
Like I told you, I'm Russian,
Lex Fridman (29:24.340)
so I tend to romanticize all things of this nature,
Lex Fridman (29:28.140)
that it's not merely cold, hard computation.
Roger Penrose (29:33.300)
Perhaps I could just slightly answer your question.
Lex Fridman (29:35.660)
You were asking me, what is it?
Roger Penrose (29:38.620)
There's something about sort of standing back
Lex Fridman (29:41.820)
and thinking about your own thought processes.
Roger Penrose (29:44.820)
I mean, there is something like that in the Gödel thing,
Lex Fridman (29:47.780)
because you're not following the rules.
Roger Penrose (29:50.260)
You're standing back and thinking about the rules.
Lex Fridman (29:53.500)
And so there is something that you might say,
Roger Penrose (29:56.940)
you think about you're doing something,
Lex Fridman (29:58.220)
and you think, what the hell am I doing?
Lex Fridman (30:00.140)
And you sort of stand back and think about
Lex Fridman (30:02.140)
what it is that's making you think in such a way.
Roger Penrose (30:05.060)
Just take a step back outside the game you've been playing.
Lex Fridman (30:08.500)
Yeah, you back up and you think about,
Roger Penrose (30:10.660)
you're just not playing the game anymore.
Lex Fridman (30:12.580)
You're thinking about what the hell you're doing
Roger Penrose (30:14.660)
in playing this game.
Lex Fridman (30:16.060)
And that's somehow,
Roger Penrose (30:18.260)
it's not a very precise description,
Lex Fridman (30:20.540)
but somehow it feels very true
Roger Penrose (30:22.260)
that that's somehow understanding.
Lex Fridman (30:24.620)
This kind of reflection.
Roger Penrose (30:26.420)
The reflection, yes.
Lex Fridman (30:27.740)
Yeah, it's a bit hard to put your finger on,
Lex Fridman (30:30.580)
but there is something there,
Lex Fridman (30:31.580)
which I think maybe could be unearthed at some point
Lex Fridman (30:34.420)
and see this is really what's going on,
Lex Fridman (30:36.860)
why conscious beings have this advantage,
Lex Fridman (30:40.100)
what it is that gives them advantage.
Lex Fridman (30:42.740)
And I think it goes way back.
Roger Penrose (30:44.220)
I don't think we're talking about the hunting dogs
Lex Fridman (30:46.780)
and the elephants.
Roger Penrose (30:48.700)
It's pretty clear that octopuses have
Lex Fridman (30:51.860)
the same sort of quality,
Lex Fridman (30:53.380)
and we call it consciousness.
Lex Fridman (30:54.460)
Yeah, I think so.
Roger Penrose (30:55.700)
Seen enough examples of the way that they behave
Lex Fridman (30:58.740)
and the evolution route is completely different.
Roger Penrose (31:03.620)
Does it go way back to some common ancestor
Lex Fridman (31:05.900)
or did it come separately?
Roger Penrose (31:07.580)
My hope is it's something simple,
Lex Fridman (31:09.380)
but the hard question if there's a hardware prerequisite.
Roger Penrose (31:13.460)
We have to develop some kind of hardware mechanisms
Lex Fridman (31:17.820)
in our computers.
Roger Penrose (31:19.180)
Like basically, as you suggest,
Lex Fridman (31:21.100)
we'll get to in a second,
Roger Penrose (31:22.580)
we kind of have to throw away the computer
Lex Fridman (31:24.460)
as we know it today.
Roger Penrose (31:26.100)
Yeah.
Lex Fridman (31:26.940)
The deterministic machines we know today
Roger Penrose (31:28.340)
to try to create it.
Lex Fridman (31:29.740)
I mean, my hope, of course, is not, but...
Roger Penrose (31:35.180)
Well, I should go really back to the story
Lex Fridman (31:37.740)
which, in a sense, I haven't finished
Roger Penrose (31:39.820)
because I went to these three courses, you see,
Lex Fridman (31:41.780)
when I was a graduate student.
Lex Fridman (31:43.900)
And so I started to think, well, I'm really,
Lex Fridman (31:46.940)
I'm a pretty, what you might call a materialist
Roger Penrose (31:49.660)
in the sense of thinking that there's no kind of mystical
Lex Fridman (31:53.620)
something or other which comes in from who knows where.
Lex Fridman (31:55.980)
You still that?
Lex Fridman (31:56.820)
Are you still, throughout your life, been a materialist?
Roger Penrose (31:58.540)
I don't like the word materialist
Lex Fridman (32:00.020)
because it suggests we know what material is.
Lex Fridman (32:02.820)
And that is a bad word because...
Lex Fridman (32:06.060)
But there's no mystical.
Roger Penrose (32:07.620)
It's not some mystical something
Lex Fridman (32:09.180)
which is not treatable by science.
Roger Penrose (32:11.740)
That's so beautifully put,
Lex Fridman (32:12.700)
just to pause on that for a second.
Roger Penrose (32:14.300)
You're a materialist, but you acknowledge
Lex Fridman (32:17.020)
that we don't really know what the material is.
Roger Penrose (32:19.140)
That's right.
Lex Fridman (32:19.980)
I mean, I like to call myself a scientist, I suppose,
Lex Fridman (32:24.300)
but it means that...
Lex Fridman (32:27.700)
Yes, well, you see, the question goes on here.
Lex Fridman (32:30.500)
So I began thinking, okay, if consciousness
Lex Fridman (32:33.180)
or understanding is something
Lex Fridman (32:35.900)
which is not a computational process, what can it be?
Lex Fridman (32:40.020)
And I knew enough from my undergraduate work.
Roger Penrose (32:42.300)
I knew about Newtonian mechanics,
Lex Fridman (32:44.500)
and I knew how basically you could put it on a computer.
Lex Fridman (32:50.140)
There is a fundamental issue, which is it important or not?
Lex Fridman (32:54.180)
That computation depends upon discrete things.
Lex Fridman (32:59.620)
So you're using discrete elements,
Lex Fridman (33:02.300)
whereas the physical laws depend on the continuum.
Lex Fridman (33:06.260)
Now, is this something to do with it?
Lex Fridman (33:09.660)
Is it the fact that we use the continuum in our physics?
Lex Fridman (33:12.820)
And if we model our physical system,
Lex Fridman (33:15.260)
we use discrete systems like ordinary computers?
Roger Penrose (33:19.020)
I came to the view that that's probably not it.
Lex Fridman (33:22.180)
I might have to retract on that someday,
Lex Fridman (33:24.860)
but the view was no, you can get close enough.
Lex Fridman (33:28.340)
It's not altogether clear, I have to say,
Lex Fridman (33:30.900)
but you can get close enough.
Lex Fridman (33:32.980)
And I went to this course by Bondi on general relativity,
Lex Fridman (33:37.020)
and I thought, well, you can put that on a computer,
Lex Fridman (33:39.500)
because that was a long time before people,
Lex Fridman (33:42.820)
and I've sort of grown up with this,
Lex Fridman (33:43.980)
how people have done better and better calculations,
Lex Fridman (33:46.220)
and they could work out about black holes,
Lex Fridman (33:48.300)
and they can then work out how black holes
Roger Penrose (33:50.380)
can interact with each other, spiral around,
Lex Fridman (33:52.700)
and what kind of gravitational waves can out.
Lex Fridman (33:55.020)
And it's a very impressive piece of computational work,
Lex Fridman (33:58.620)
how you can actually work out the shapes of those signals.
Lex Fridman (34:01.900)
And now we have LIGO seeing these signals,
Lex Fridman (34:04.020)
and they say, yeah, those black holes spiral into each other.
Roger Penrose (34:07.340)
This is just a vindication of the power of computation
Lex Fridman (34:11.700)
in describing Einstein's general relativity.
Lex Fridman (34:16.020)
So in that case, we can get close,
Lex Fridman (34:18.620)
but with computation, we can get close
Roger Penrose (34:22.060)
to our understanding of the physics.
Lex Fridman (34:23.340)
You can get very, very close.
Lex Fridman (34:24.620)
Now, is that close enough, you see?
Lex Fridman (34:26.900)
And then I went to this course by Dirac.
Roger Penrose (34:29.620)
Now, you see, I think it was the very first lecture
Lex Fridman (34:32.500)
that he gave, and he was talking about
Roger Penrose (34:35.420)
a superposition principle.
Lex Fridman (34:37.500)
And he said, if you have a particle,
Roger Penrose (34:39.900)
you usually think of particle can be over here
Lex Fridman (34:41.860)
or over there, but in quantum mechanics,
Roger Penrose (34:44.100)
it can be over here and over there at the same time.
Lex Fridman (34:48.060)
And you have these states which involve
Roger Penrose (34:50.500)
a superposition in some sense
Lex Fridman (34:52.740)
of different locations for that particle.
Lex Fridman (34:56.660)
And then he got out his piece of chalk.
Lex Fridman (34:58.540)
Some people say he broke it in two
Roger Penrose (35:00.020)
as a kind of illustration of how the piece of chalk
Lex Fridman (35:03.020)
might be over here and over there at the same time.
Lex Fridman (35:06.700)
And he was talking about this, and my mind wandered.
Lex Fridman (35:10.900)
I don't remember what he said.
Roger Penrose (35:13.340)
All I can remember, he's just moved on to the next topic,
Lex Fridman (35:16.460)
and something about energy he'd mentioned,
Roger Penrose (35:18.580)
which I had no idea what it had to do with anything.
Lex Fridman (35:21.020)
And so I'd been struck with this
Lex Fridman (35:22.900)
and worried about it ever since.
Lex Fridman (35:25.260)
It's probably just as well I didn't hear his explanation
Roger Penrose (35:27.780)
because it was probably one of these things
Lex Fridman (35:29.340)
to calm me down and not worry about it anymore.
Roger Penrose (35:32.100)
Whereas in my case, I've worried about it ever since.
Lex Fridman (35:35.900)
So I thought maybe that's the catch.
Roger Penrose (35:38.420)
There is something in quantum mechanics
Lex Fridman (35:41.220)
where the superpositions become one or the other,
Lex Fridman (35:45.060)
and that's not part of quantum mechanics.
Lex Fridman (35:47.820)
There's something missing in the theory.
Roger Penrose (35:50.020)
The theory is incomplete.
Lex Fridman (35:51.620)
It's not just incomplete.
Roger Penrose (35:52.580)
It's in a certain sense not quite right
Lex Fridman (35:54.900)
because if you follow the equation,
Roger Penrose (35:57.500)
the basic equation of quantum mechanics,
Lex Fridman (35:59.340)
that's the Schrodinger equation,
Roger Penrose (36:01.220)
you could put that on a computer too.
Lex Fridman (36:02.660)
There are lots of difficulties
Roger Penrose (36:03.780)
about how many parameters you have to put in and so on.
Lex Fridman (36:06.180)
That can be very tricky,
Lex Fridman (36:07.500)
but nevertheless, it is a computational process.
Lex Fridman (36:10.860)
Modulo this question about the continuum as before,
Lex Fridman (36:14.940)
but it's not clear that makes any difference.
Lex Fridman (36:16.900)
So our theories of quantum mechanics
Roger Penrose (36:18.940)
may be missing the same element
Lex Fridman (36:20.980)
that the universal Turing machine
Roger Penrose (36:23.740)
is missing about consciousness.
Lex Fridman (36:25.500)
Yes, yes.
Roger Penrose (36:26.420)
Yeah, this is the view I held is that you need a theory
Lex Fridman (36:29.700)
and that what people call the reduction of the state
Roger Penrose (36:33.580)
or the collapse of the wave function,
Lex Fridman (36:35.780)
which you have to have,
Roger Penrose (36:36.780)
otherwise quantum mechanics doesn't relate
Lex Fridman (36:38.500)
to the world we see.
Roger Penrose (36:39.900)
To make it relate to the world we see,
Lex Fridman (36:41.420)
you've got to break the Schrodinger equation.
Roger Penrose (36:45.140)
Schrodinger himself was absolutely appalled by this idea,
Lex Fridman (36:49.220)
his own equation.
Roger Penrose (36:50.900)
I mean, that's why he introduced
Lex Fridman (36:52.620)
this famous Schrodinger's cat as a thought experiment.
Roger Penrose (36:56.340)
He's really saying, look,
Lex Fridman (36:57.180)
this is where my equation leads you into it.
Roger Penrose (36:59.580)
There's something wrong,
Lex Fridman (37:01.340)
something we haven't understood,
Roger Penrose (37:02.620)
which is basically fundamental.
Lex Fridman (37:05.260)
And so I was trying to put all these things together
Lex Fridman (37:07.860)
and said, well, it's got to be
Lex Fridman (37:09.100)
the noncomputability comes in there.
Lex Fridman (37:11.860)
And I also can't quite remember when I thought this,
Lex Fridman (37:14.780)
but it's when gravity is involved in quantum mechanics.
Roger Penrose (37:18.100)
It's the combination of those two.
Lex Fridman (37:19.820)
And that's that point
Roger Penrose (37:22.260)
when you have good reasons to believe,
Lex Fridman (37:25.980)
this came much later,
Roger Penrose (37:27.580)
that I have good reason to believe
Lex Fridman (37:29.860)
that the principles of general relativity
Lex Fridman (37:32.860)
and those of quantum mechanics,
Lex Fridman (37:34.180)
most particularly,
Roger Penrose (37:35.980)
it's the basic principle of equivalence,
Lex Fridman (37:39.260)
which goes back to Galileo.
Roger Penrose (37:41.340)
If you fall freely,
Lex Fridman (37:43.580)
you eliminate the gravitational field.
Lex Fridman (37:46.420)
So you imagine Galileo
Lex Fridman (37:49.660)
dropping his big rock and his little rock
Roger Penrose (37:51.460)
from the leaning tower,
Lex Fridman (37:52.580)
whether he actually ever did that or not,
Roger Penrose (37:54.300)
pretty irrelevant.
Lex Fridman (37:55.580)
And as the rocks fall to the ground,
Roger Penrose (37:57.780)
you have a little insect sitting on one of them,
Lex Fridman (37:59.820)
looking at the other one.
Lex Fridman (38:01.380)
And it seems to think, oh, there's no gravity here.
Lex Fridman (38:04.220)
Of course, it hits the ground
Lex Fridman (38:05.340)
and then you realize something's difference going on.
Lex Fridman (38:07.900)
But when it's in free fall,
Roger Penrose (38:10.140)
the gravity has been eliminated.
Lex Fridman (38:11.980)
Galileo understood that very beautifully.
Roger Penrose (38:15.420)
He gives these wonderful examples of fireworks.
Lex Fridman (38:18.540)
And you see the fireworks and explode,
Lex Fridman (38:20.380)
and you see this fear of sparkling fireworks.
Lex Fridman (38:23.500)
It remains as fear as it falls down,
Roger Penrose (38:26.860)
as though there were no gravity.
Lex Fridman (38:29.260)
So he understood that principle,
Lex Fridman (38:31.300)
but he couldn't make a theory out of it.
Lex Fridman (38:33.580)
Einstein came along,
Roger Penrose (38:34.620)
used exactly the same principle.
Lex Fridman (38:36.780)
And that's the basis
Roger Penrose (38:38.060)
of Einstein's general theory of relativity.
Lex Fridman (38:41.420)
Now, there is a conflict.
Roger Penrose (38:43.580)
This is something I did much, much later.
Lex Fridman (38:45.260)
So this wasn't at those days,
Roger Penrose (38:47.540)
much, much later.
Lex Fridman (38:48.940)
You can see there is a basic conflict
Roger Penrose (38:51.460)
between the principle of superposition,
Lex Fridman (38:54.580)
the thing that Dirac was talking about,
Lex Fridman (38:56.380)
and the principle of general covariance.
Lex Fridman (38:58.740)
Well, principle of equivalence.
Roger Penrose (39:01.060)
Gravitational field's equivalent to an acceleration.
Lex Fridman (39:03.740)
Can you pause for a second?
Lex Fridman (39:04.780)
What is the principle of equivalence?
Lex Fridman (39:06.900)
It's this Galileo principle
Roger Penrose (39:08.300)
that we can eliminate, at least locally.
Lex Fridman (39:11.580)
You have to be in a small neighborhood
Roger Penrose (39:13.580)
because if you have people dropping rocks
Lex Fridman (39:16.460)
all around the world somewhere,
Roger Penrose (39:18.100)
you can't get rid of it all at once.
Lex Fridman (39:19.940)
But in the local neighborhood,
Roger Penrose (39:22.100)
you can eliminate the gravitational field
Lex Fridman (39:24.300)
by falling freely with it.
Lex Fridman (39:26.820)
And we now see this with astronauts,
Lex Fridman (39:28.540)
and they don't, you know, the Earth is right there.
Roger Penrose (39:30.700)
You can see the great globe of the Earth
Lex Fridman (39:32.580)
right beneath them.
Lex Fridman (39:33.980)
But they don't care about it.
Lex Fridman (39:35.460)
As far as they're concerned, there's no gravity.
Roger Penrose (39:39.140)
They fall freely within the gravitational field,
Lex Fridman (39:42.140)
and that gets rid of the gravitational field.
Lex Fridman (39:45.140)
And that's the principle of equivalence.
Lex Fridman (39:46.740)
So what's the contradiction?
Roger Penrose (39:48.980)
What's the tension with superposition
Lex Fridman (39:50.460)
and equivalence?
Roger Penrose (39:51.300)
Oh, well, that's technical.
Lex Fridman (39:52.780)
So just to backtrack for a second
Roger Penrose (39:55.100)
just to see if we can weave a thread through it all.
Lex Fridman (39:57.980)
So we started to think about consciousness
Roger Penrose (40:02.340)
as potentially needing some of the same,
Lex Fridman (40:06.740)
not mystical, but some of the same magic.
Roger Penrose (40:08.780)
You see, it is a complicated story.
Lex Fridman (40:10.580)
So, you know, people think,
Roger Penrose (40:11.820)
oh, I'm drifting away from the point or something.
Lex Fridman (40:14.180)
But I think it is a complicated story.
Lex Fridman (40:16.700)
So what I'm trying to say,
Lex Fridman (40:17.780)
I mean, I try to put it in a nutshell,
Lex Fridman (40:19.380)
but it's not so easy.
Lex Fridman (40:20.700)
I'm trying to say that whatever consciousness is,
Roger Penrose (40:24.900)
it's not a computation.
Lex Fridman (40:27.220)
Or it's not a physical process
Roger Penrose (40:29.260)
which can be described by computation.
Lex Fridman (40:33.340)
But it nevertheless could be,
Lex Fridman (40:34.860)
so one of the interesting models
Lex Fridman (40:37.940)
that you've proposed
Roger Penrose (40:39.860)
is the orchestrated objective reduction.
Lex Fridman (40:41.980)
Yes, well, you see, that's going from there, you see.
Lex Fridman (40:44.660)
So I say I have no idea.
Lex Fridman (40:46.740)
So I wrote this book through my scientific career.
Roger Penrose (40:50.340)
I thought, you know, when I'm retired,
Lex Fridman (40:52.660)
I'll have enough time to write a sort of a popularish book
Roger Penrose (40:56.860)
which I will explain my ideas and puzzles,
Lex Fridman (41:01.180)
what I like, beautiful things about physics and mathematics,
Lex Fridman (41:04.140)
and this puzzle about computability
Lex Fridman (41:07.460)
and consciousness and so on.
Lex Fridman (41:09.540)
And in the process of writing this book,
Lex Fridman (41:13.100)
well, I thought I'd do it when I was retired.
Roger Penrose (41:14.460)
I didn't actually, I didn't wait that long
Lex Fridman (41:16.260)
because there was a radio discussion
Roger Penrose (41:19.380)
between Edward Fredkin and Marvin Minsky.
Lex Fridman (41:24.140)
And they were talking about what computers could do.
Lex Fridman (41:28.180)
And they were entering a big room.
Lex Fridman (41:30.540)
They imagined entering this big room
Roger Penrose (41:32.020)
where at the other end of the room,
Lex Fridman (41:33.780)
two computers were talking to each other.
Lex Fridman (41:36.900)
And as you walk up to the computers,
Lex Fridman (41:39.220)
they will have communicated to each other
Roger Penrose (41:41.700)
more ideas, concepts, things than the entire human race
Lex Fridman (41:46.620)
had ever done.
Lex Fridman (41:49.100)
So I thought, well, I know where you're coming from,
Lex Fridman (41:51.620)
but I just don't believe you.
Roger Penrose (41:53.620)
There's something missing.
Lex Fridman (41:57.020)
So I thought, well, I should write my book.
Lex Fridman (42:00.380)
And so I did.
Lex Fridman (42:01.620)
It was roughly the same time Stephen Hawking
Roger Penrose (42:04.060)
was writing his brief history of time.
Lex Fridman (42:07.620)
In the 80s at some point.
Roger Penrose (42:11.220)
The book you're talking about is The Emperor's New Mind.
Lex Fridman (42:12.860)
The Emperor's New Mind, that's right.
Lex Fridman (42:13.980)
And both are incredible books,
Lex Fridman (42:16.140)
The Brief History of Time and The Emperor's New Mind.
Roger Penrose (42:18.500)
Yes, it was quite interesting
Lex Fridman (42:19.900)
because he told me he'd got Carl Sagan, I think,
Roger Penrose (42:23.460)
to write a foreword for the book, you see.
Lex Fridman (42:26.580)
So I thought, gosh, what am I gonna do?
Roger Penrose (42:28.220)
I'm not gonna get anywhere unless I get somebody.
Lex Fridman (42:31.060)
So I said, oh, I know Martin Gardner,
Lex Fridman (42:32.700)
so I wonder if he'd do it.
Lex Fridman (42:34.380)
So he did, and he did a very nice foreword.
Lex Fridman (42:36.660)
So that's an incredible book,
Lex Fridman (42:38.260)
and some of the same people you mentioned,
Roger Penrose (42:40.420)
Ed Franken, which I guess of expert systems fame,
Lex Fridman (42:44.620)
and Minsky, of course, people know in the AI world,
Lex Fridman (42:46.980)
but they represent the artificial intelligence world
Lex Fridman (42:49.820)
that do hope and dream that AI's intelligence is.
Roger Penrose (42:53.740)
Well, you see, it was my thinking,
Lex Fridman (42:54.860)
well, you know, I see where they're coming from.
Roger Penrose (42:57.420)
From that perspective, yeah, you're right.
Lex Fridman (42:59.940)
But that's not my perspective.
Lex Fridman (43:01.620)
So I thought I had to say it.
Lex Fridman (43:03.460)
And as I was writing my book, you see,
Roger Penrose (43:05.060)
I thought, well, I don't really know anything
Lex Fridman (43:06.740)
about neurophysiology.
Lex Fridman (43:07.780)
What am I doing writing this book?
Lex Fridman (43:09.220)
So I started reading up about neurophysiology,
Lex Fridman (43:12.140)
and I read up, and I think,
Lex Fridman (43:13.100)
now, I'm trying to find out how it is
Roger Penrose (43:14.580)
that nerve signals could possibly
Lex Fridman (43:16.460)
preserve quantum coherence.
Lex Fridman (43:18.340)
And all I read is that the electrical signals
Lex Fridman (43:20.900)
which go along the nerves create effects through the brain.
Roger Penrose (43:25.540)
There's no chance you can isolate it.
Lex Fridman (43:28.260)
So I thought, this is hopeless.
Lex Fridman (43:29.860)
So I come to the end of the book,
Lex Fridman (43:31.660)
and I more or less give up.
Roger Penrose (43:33.580)
I just think of something which I didn't believe in.
Lex Fridman (43:36.380)
Maybe this is a way around it, but no.
Lex Fridman (43:39.460)
And then, you see, I thought, well,
Lex Fridman (43:40.540)
maybe this book will at least stimulate young people
Roger Penrose (43:43.380)
to do science or something.
Lex Fridman (43:45.140)
And I got all these letters from old, retired people instead.
Roger Penrose (43:48.420)
These are the only people who had time to read my book.
Lex Fridman (43:52.260)
So, I mean, but.
Roger Penrose (43:53.100)
Except for Stuart Hameroff.
Lex Fridman (43:54.900)
Except for Stuart Hameroff.
Roger Penrose (43:56.420)
Stuart Hameroff wrote to me, and he said,
Lex Fridman (43:58.460)
I think you're missing something.
Lex Fridman (44:01.060)
You don't know about microtubules, do you?
Lex Fridman (44:03.420)
He didn't put it quite like that.
Lex Fridman (44:04.820)
But that was more or less it.
Lex Fridman (44:05.940)
And he said, this is what you really need to consider.
Lex Fridman (44:08.860)
So I thought, my God, yes.
Lex Fridman (44:10.620)
That's a much more promising structure.
Roger Penrose (44:12.980)
So, I mean, fundamentally, you were searching
Lex Fridman (44:16.340)
for the source of, noncomputable source of consciousness
Roger Penrose (44:22.100)
within the human brain, in the biology.
Lex Fridman (44:25.060)
And so, what are, if I may ask, what are microtubules?
Roger Penrose (44:30.060)
Well, you see, I was ignorant in what I'd read.
Lex Fridman (44:33.860)
I never came across them in the books I looked at.
Roger Penrose (44:37.700)
Perhaps I only read rather superficially, which is true.
Lex Fridman (44:40.860)
But I didn't know about microtubules.
Roger Penrose (44:43.100)
Stuart, I think one of the things
Lex Fridman (44:45.300)
that impressed him about them was,
Roger Penrose (44:47.060)
when you see pictures of mitosis, that's a cell dividing,
Lex Fridman (44:51.380)
and you see all the chromosomes.
Lex Fridman (44:53.300)
And the chromosomes, they all get lined up,
Lex Fridman (44:55.700)
and then they get pulled apart.
Lex Fridman (44:57.980)
And so, as the cell divides, half the chromosomes go,
Lex Fridman (45:02.100)
they divide into the two parts,
Lex Fridman (45:04.940)
and they go two different ways.
Lex Fridman (45:07.460)
And what is it that's pulling them apart?
Roger Penrose (45:09.860)
Well, those are these little things called microtubules.
Lex Fridman (45:12.900)
And so, he started to get interested in them.
Lex Fridman (45:15.580)
And he formed the view, well, he was,
Lex Fridman (45:18.900)
his day job or night job or whatever you call it,
Roger Penrose (45:21.100)
is to put people to sleep,
Lex Fridman (45:23.060)
except he doesn't like calling it sleep
Roger Penrose (45:24.700)
because it's different.
Lex Fridman (45:25.820)
General anesthetics in a reversible way.
Roger Penrose (45:29.340)
So, you want to make sure that they don't experience
Lex Fridman (45:32.500)
the pain that would otherwise be something that they feel.
Lex Fridman (45:36.780)
And consciousness is turned off for a while,
Lex Fridman (45:40.380)
and it can be turned back on again.
Roger Penrose (45:41.940)
So, it's crucial that you can turn it off and turn it on.
Lex Fridman (45:44.980)
And what do you do when you're doing that?
Lex Fridman (45:47.460)
What do general anesthetic gases do?
Lex Fridman (45:50.580)
And see, he formed the view that it's the microtubules
Roger Penrose (45:54.980)
that they affect.
Lex Fridman (45:56.860)
And the details of why he formed that view is not,
Roger Penrose (46:01.020)
well, they're clear to me,
Lex Fridman (46:02.300)
but there's an interesting story he keeps talking about.
Lex Fridman (46:05.660)
But I found this very exciting
Lex Fridman (46:08.500)
because I thought these structures,
Roger Penrose (46:11.500)
these little tubes which inhabit pretty well all cells,
Lex Fridman (46:15.420)
it's not just neurons,
Roger Penrose (46:17.980)
apart from red blood cells,
Lex Fridman (46:20.580)
they inhabit pretty well all the other cells in the body.
Lex Fridman (46:23.940)
But they're not all the same kind.
Lex Fridman (46:25.380)
You get different kinds of microtubules.
Lex Fridman (46:28.020)
And the ones that excited me the most,
Lex Fridman (46:31.780)
this may still not be totally clear,
Lex Fridman (46:34.500)
but the ones that excited me most
Lex Fridman (46:36.180)
were the only ones that I knew about at the time
Roger Penrose (46:39.300)
because they're very, very symmetrical structures.
Lex Fridman (46:44.180)
And I had reason to believe
Roger Penrose (46:45.620)
that these very symmetrical structures
Lex Fridman (46:48.100)
would be much better at preserving a quantum state,
Roger Penrose (46:52.140)
quantum coherence, preserving the thing without,
Lex Fridman (46:55.700)
you just need to preserve certain degrees of freedom
Roger Penrose (46:58.780)
without them leaking into the environment.
Lex Fridman (47:01.060)
Once they leak into the environment, you're lost.
Lex Fridman (47:03.420)
So you've got to preserve these quantum states at a level
Lex Fridman (47:08.140)
which the state reduction process comes in
Lex Fridman (47:12.420)
and that's where I think the noncomputability comes in
Lex Fridman (47:17.380)
and it's the measurement process in quantum mechanics,
Roger Penrose (47:19.700)
what's going on.
Lex Fridman (47:20.820)
So something about the measurement process
Lex Fridman (47:23.580)
and what's going on,
Lex Fridman (47:24.420)
something about the structure of the microtubules,
Roger Penrose (47:27.140)
your intuition says maybe there's something here,
Lex Fridman (47:29.540)
maybe this kind of structure allows
Roger Penrose (47:32.500)
for the mystery of the quantum mechanics.
Lex Fridman (47:35.500)
There was a much better chance, yes.
Roger Penrose (47:37.260)
It just struck me that partly it was the symmetry
Lex Fridman (47:40.780)
because there is a feature of symmetry
Roger Penrose (47:43.180)
you can preserve quantum coherence
Lex Fridman (47:46.300)
much better with symmetrical structures.
Roger Penrose (47:48.140)
There's a good reason for that.
Lex Fridman (47:50.340)
And that impressed me a lot.
Roger Penrose (47:52.540)
I didn't know the difference between the A lattice
Lex Fridman (47:54.700)
and B lattice at that time, which could be important.
Roger Penrose (47:57.940)
Now that could even, see, which isn't talked about much.
Lex Fridman (48:00.860)
But that's some, in some sense, details.
Roger Penrose (48:02.620)
We've got to take a step back just to say
Lex Fridman (48:04.380)
in case people are not familiar.
Lex Fridman (48:06.140)
So this was called the orchestrated objective reduction
Lex Fridman (48:13.220)
idea or ORCOR, which is a biological philosophy of mind
Roger Penrose (48:18.220)
that postulates that consciousness originates
Lex Fridman (48:20.740)
at the quantum level inside neurons.
Lex Fridman (48:22.340)
So that has to do with your search for where,
Lex Fridman (48:25.340)
where is it coming from?
Lex Fridman (48:26.700)
So that's counter to the notion that consciousness
Lex Fridman (48:29.580)
may arise from the computation performed by the synapses.
Roger Penrose (48:33.220)
Yes, I think the key point.
Lex Fridman (48:35.620)
Sometimes people say it's because it's quantum mechanical.
Roger Penrose (48:40.820)
It's not just that.
Lex Fridman (48:42.660)
See, it's more outrageous than that.
Roger Penrose (48:45.060)
You see, this is one reason I think
Lex Fridman (48:46.300)
we're so far off from it,
Roger Penrose (48:48.340)
because we don't even know the physics right.
Lex Fridman (48:51.060)
You see, it's not just quantum mechanics.
Roger Penrose (48:53.860)
People say, oh, you know, quantum systems
Lex Fridman (48:55.900)
and biological structures.
Roger Penrose (48:57.340)
No, will you starting to see that
Lex Fridman (49:00.340)
some basic biological systems does depend on quantum.
Roger Penrose (49:05.900)
I mean, look, in the first place,
Lex Fridman (49:07.620)
all of chemistry is quantum mechanics.
Roger Penrose (49:09.860)
People got used to that, so they don't count that.
Lex Fridman (49:13.140)
So he said, let's not count quantum chemistry.
Roger Penrose (49:16.660)
We sort of got the hang of that, I think.
Lex Fridman (49:19.100)
But you have quantum effects,
Roger Penrose (49:21.340)
which are not just chemical, in photosynthesis.
Lex Fridman (49:25.460)
And this is one of the striking things
Roger Penrose (49:27.220)
in the last several years,
Lex Fridman (49:29.300)
that photosynthesis seems to be a basically quantum process,
Roger Penrose (49:34.220)
which is not simply chemical.
Lex Fridman (49:36.860)
It's using quantum mechanics in a very basic way.
Lex Fridman (49:41.460)
So you could start saying, oh, well,
Lex Fridman (49:43.100)
if photosynthesis is based on quantum mechanics,
Lex Fridman (49:45.580)
why not behavior of neurons and things like that?
Lex Fridman (49:50.260)
Maybe there's something
Roger Penrose (49:52.140)
which is a bit like photosynthesis in that respect.
Lex Fridman (49:55.060)
But what I'm saying is even more outrageous than that,
Roger Penrose (49:58.140)
because those things are talking
Lex Fridman (50:00.780)
about conventional quantum mechanics.
Roger Penrose (50:03.700)
Now, my argument says that conventional quantum mechanics,
Lex Fridman (50:07.540)
if you're just following the Schrodinger equation,
Roger Penrose (50:09.420)
that's still computable.
Lex Fridman (50:11.700)
So you've got to go beyond that.
Lex Fridman (50:13.900)
So you've got to go to where
Lex Fridman (50:17.420)
quantum mechanics goes wrong in a certain sense.
Roger Penrose (50:21.940)
You have to be a little bit careful about that,
Lex Fridman (50:23.820)
because the way people do quantum mechanics
Roger Penrose (50:26.060)
is a sort of mixture of two different processes.
Lex Fridman (50:32.820)
One of them is the Schrodinger equation,
Roger Penrose (50:35.460)
which is an equation Schrodinger wrote down,
Lex Fridman (50:38.820)
and it tells you how the state of a system evolves.
Lex Fridman (50:42.580)
And it evolves according to this equation,
Lex Fridman (50:44.740)
completely deterministic,
Lex Fridman (50:47.300)
but it evolves into ridiculous situations.
Lex Fridman (50:50.300)
And this was what Schrodinger
Roger Penrose (50:51.540)
was very much pointing out with his cat.
Lex Fridman (50:54.260)
He said, you follow my equation,
Roger Penrose (50:55.820)
that's Schrodinger's equation,
Lex Fridman (50:57.380)
and you could say that you have to get a cat,
Roger Penrose (51:01.300)
a cat which is dead and alive at the same time.
Lex Fridman (51:04.260)
That would be the evolution of the Schrodinger equation,
Roger Penrose (51:07.140)
would lead to a state, which is the cat being dead
Lex Fridman (51:10.380)
and alive at the same time.
Lex Fridman (51:12.700)
And he's more or less saying, this is an absurdity.
Lex Fridman (51:16.620)
People nowadays say, oh, well, Schrodinger said
Roger Penrose (51:18.380)
you can have a cat which is dead, that's not that.
Lex Fridman (51:20.140)
You see, he was saying, this is an absurdity.
Roger Penrose (51:23.380)
There's something missing.
Lex Fridman (51:25.620)
And that the reduction of the state
Roger Penrose (51:28.620)
or the collapse of the wave function or whatever it is,
Lex Fridman (51:31.940)
is something which has to be understood.
Roger Penrose (51:34.700)
It's not following the Schrodinger equation.
Lex Fridman (51:37.780)
It's not the way we conventionally do quantum mechanics.
Roger Penrose (51:41.940)
There's something more than that.
Lex Fridman (51:44.700)
And it's easy to quote authority here because Einstein,
Roger Penrose (51:49.820)
at least three of the greatest physicists
Lex Fridman (51:52.540)
of 20th century who were very fundamental
Roger Penrose (51:57.180)
in developing quantum mechanics,
Lex Fridman (51:58.780)
Einstein, one of them, Schrodinger, another,
Roger Penrose (52:01.820)
Dirac, another.
Lex Fridman (52:03.580)
You have to look carefully at Dirac's writing
Roger Penrose (52:05.500)
because he didn't tend to say this out loud too much
Lex Fridman (52:09.180)
because he was very cautious about what he said.
Roger Penrose (52:11.300)
You find the right place and you see he says
Lex Fridman (52:14.220)
quantum mechanics is a provisional theory.
Roger Penrose (52:18.060)
We need something which explains
Lex Fridman (52:21.660)
the collapse of the wave function.
Roger Penrose (52:23.500)
We need to go beyond the theory we have now.
Lex Fridman (52:27.900)
I happen to be one of the kinds of people,
Roger Penrose (52:29.900)
there are many, there is a whole group of people,
Lex Fridman (52:31.860)
they're all considered to be a bit mavericks,
Roger Penrose (52:35.580)
who believe that quantum mechanics needs to be modified.
Lex Fridman (52:38.900)
There's a small minority of those people,
Roger Penrose (52:41.180)
which are already a minority,
Lex Fridman (52:42.740)
who think that the way in which it's modified
Roger Penrose (52:46.220)
has to be with gravity.
Lex Fridman (52:48.700)
And there is an even smaller minority of those people
Roger Penrose (52:51.420)
who think it's the particular way that I think it is.
Lex Fridman (52:53.580)
You see.
Lex Fridman (52:55.180)
So those are the quantum gravity folks.
Lex Fridman (52:56.860)
But what's...
Roger Penrose (52:57.700)
You see, quantum gravity is already not this.
Lex Fridman (53:00.740)
Because when you say quantum gravity,
Lex Fridman (53:02.660)
what you really mean is quantum mechanics
Lex Fridman (53:05.460)
applied to gravitational theory.
Lex Fridman (53:08.020)
So you say, let's take this wonderful formalism
Lex Fridman (53:10.660)
of quantum mechanics and make gravity fit into it.
Lex Fridman (53:15.220)
So that is what quantum gravity is meant to be.
Lex Fridman (53:18.060)
Now I'm saying you've got to be more even handed
Roger Penrose (53:21.500)
that gravity affects the structure of quantum mechanics too.
Lex Fridman (53:24.460)
It's not just you quantize gravity,
Roger Penrose (53:26.860)
you've got to gravitate quantum mechanics.
Lex Fridman (53:29.460)
And it's a two way thing.
Lex Fridman (53:31.140)
But then when do you even get started?
Lex Fridman (53:32.980)
So that you're saying that we have to figure out
Roger Penrose (53:35.260)
a totally new ideas in there.
Lex Fridman (53:36.860)
Exactly.
Roger Penrose (53:37.940)
No, you're stuck.
Lex Fridman (53:39.980)
You don't have a theory.
Roger Penrose (53:41.260)
That's the trouble.
Lex Fridman (53:42.780)
So this is a big problem.
Lex Fridman (53:44.540)
If you say, okay, well, what's the theory?
Lex Fridman (53:46.020)
I don't know.
Lex Fridman (53:47.300)
So maybe in the very early days, sort of...
Lex Fridman (53:49.420)
It is in the very early days.
Lex Fridman (53:51.020)
But just making this point.
Lex Fridman (53:52.620)
Yes.
Roger Penrose (53:53.780)
You see, Stuart Hammeroff tends to be,
Lex Fridman (53:55.780)
oh, Penrose says that it's got to be a reduction
Roger Penrose (53:58.700)
of the state and so on, so let's use it.
Lex Fridman (54:00.620)
The trouble is Penrose doesn't say that.
Roger Penrose (54:02.140)
Penrose says, well, I think that we have no experiments
Lex Fridman (54:06.940)
as yet, which shows that.
Roger Penrose (54:10.100)
There are experiments which are being thought through
Lex Fridman (54:12.580)
and which I'm hoping will be performed.
Roger Penrose (54:15.740)
There is an experiment which is being developed
Lex Fridman (54:18.340)
by Dirk Baumeister, who I've known for a long time,
Roger Penrose (54:22.060)
who shares his time between Leiden in the Netherlands
Lex Fridman (54:25.340)
and Santa Barbara in the US.
Lex Fridman (54:27.900)
And he's been working on an experiment
Lex Fridman (54:29.700)
which could perhaps demonstrate that quantum mechanics,
Roger Penrose (54:35.180)
as we now understand it, if you don't bring in
Lex Fridman (54:37.420)
the gravitational effects, it has to be modified.
Lex Fridman (54:42.580)
And then there's also experiments that are underway
Lex Fridman (54:45.980)
that kind of look at the microtubule side of things
Roger Penrose (54:50.620)
to see if there's, in the biology,
Lex Fridman (54:52.580)
you could see something like that.
Lex Fridman (54:53.820)
Could you briefly mention it?
Lex Fridman (54:55.060)
Because that's really sort of one of the only
Roger Penrose (54:58.140)
experimental attempts in the very early days
Lex Fridman (55:00.860)
of even thinking about consciousness.
Roger Penrose (55:02.740)
I think there's a very serious area here,
Lex Fridman (55:05.420)
which is what Stuart Hammeroff is doing,
Lex Fridman (55:07.300)
and I think it's very important.
Lex Fridman (55:09.020)
One of the few places that you can really get
Roger Penrose (55:11.740)
a bit of a handle on what consciousness is
Lex Fridman (55:14.780)
is what turns it off.
Lex Fridman (55:17.040)
And when you're thinking about general anesthetics,
Lex Fridman (55:20.020)
it's very specific.
Roger Penrose (55:21.660)
These things turn consciousness off.
Lex Fridman (55:24.220)
What the hell do they do?
Roger Penrose (55:26.300)
Well, Stuart and a number of people who work with him
Lex Fridman (55:29.900)
and others happen to believe that the general anesthetics
Roger Penrose (55:34.420)
directly affect microtubules.
Lex Fridman (55:36.720)
And there is some evidence for this.
Roger Penrose (55:38.660)
I don't know how strong it is
Lex Fridman (55:40.180)
and how watertight the case is,
Lex Fridman (55:43.800)
but I think there is some evidence pointing
Lex Fridman (55:46.740)
in that kind of direction.
Roger Penrose (55:49.140)
It's not just an ordinary chemical process.
Lex Fridman (55:51.180)
There's something quite different about it.
Lex Fridman (55:53.500)
And one of the main candidates
Lex Fridman (55:56.900)
is that these anesthetic gases
Roger Penrose (55:59.260)
do affect directly microtubules.
Lex Fridman (56:02.620)
And how strong that evidence is,
Roger Penrose (56:04.460)
I wouldn't be in a position to say,
Lex Fridman (56:07.100)
but I think there is fairly impressive evidence.
Lex Fridman (56:10.060)
And the point is the experiments are being undertaken,
Lex Fridman (56:12.700)
which is. Yeah.
Roger Penrose (56:13.540)
I mean, that is experimental.
Lex Fridman (56:14.660)
You see, so it's a very clear direction
Roger Penrose (56:17.260)
where you can think of experiments
Lex Fridman (56:18.720)
which could indicate whether or not
Roger Penrose (56:21.800)
it's really microtubules which the anesthetic gases
Lex Fridman (56:24.980)
directly affect.
Roger Penrose (56:26.100)
That's really exciting.
Lex Fridman (56:27.300)
One of the sad things is as far as I'm,
Roger Penrose (56:30.380)
from my outside perspective,
Lex Fridman (56:31.820)
is not many people are working on this.
Lex Fridman (56:34.420)
So there's a very, like with Stuart,
Lex Fridman (56:37.220)
it feels like there's very few people
Roger Penrose (56:38.940)
are carrying the flag forward on this.
Lex Fridman (56:41.280)
I think it's not many in the sense it's a minority,
Lex Fridman (56:44.860)
but it's not zero anymore.
Lex Fridman (56:46.420)
You see, when Stuart and I were originally taught by us,
Roger Penrose (56:49.840)
we were just us and a few of our friends,
Lex Fridman (56:52.860)
there weren't many people taking it,
Lex Fridman (56:54.220)
but it's grown into one of the main viewpoints.
Lex Fridman (56:59.500)
There might be about four or five or six different
Roger Penrose (57:03.540)
views which people hold,
Lex Fridman (57:06.260)
and it's one of them.
Lex Fridman (57:07.660)
So it's considered as one of the possible
Lex Fridman (57:12.060)
lines of thinking, yes.
Roger Penrose (57:13.340)
You describe physics theories
Lex Fridman (57:15.100)
as falling into one of three categories,
Roger Penrose (57:16.940)
the superb, the useful, or the tentative.
Lex Fridman (57:19.860)
I like those words.
Roger Penrose (57:21.700)
It's a beautiful categorization.
Lex Fridman (57:23.580)
Do you think we'll ever have a superb theory
Lex Fridman (57:26.980)
of intelligence and of consciousness?
Lex Fridman (57:29.800)
We might.
Roger Penrose (57:31.700)
We're a long way from it.
Lex Fridman (57:33.740)
I don't think we're even,
Roger Penrose (57:35.020)
whether we're in the tentative scale.
Lex Fridman (57:36.940)
I mean, it's...
Lex Fridman (57:40.020)
You don't think we've even entered the realm of tentative?
Lex Fridman (57:42.420)
Probably not.
Roger Penrose (57:43.260)
Yeah, that's right.
Lex Fridman (57:44.580)
Now, when you see this, it's so controversial.
Roger Penrose (57:47.140)
We don't have a clear view
Lex Fridman (57:49.180)
which is accepted by a majority.
Roger Penrose (57:53.100)
I mean, you see, yeah, people,
Lex Fridman (57:54.340)
most views are computational in one form or another.
Roger Penrose (57:57.300)
They think it's some, but it's not very clear,
Lex Fridman (57:59.260)
because even the IIT people who
Roger Penrose (58:04.700)
think of them as computational,
Lex Fridman (58:06.540)
but I've heard them say,
Roger Penrose (58:08.020)
no, consciousness is supposed to be not computational.
Lex Fridman (58:09.980)
I say, well, if it's not computational,
Lex Fridman (58:10.980)
what in the hell is it?
Lex Fridman (58:12.140)
What's going on?
Lex Fridman (58:14.100)
What physical processes are going on which are that?
Lex Fridman (58:18.900)
What does it mean for something to be computational then?
Roger Penrose (58:21.700)
So, is...
Lex Fridman (58:25.100)
Well, there has to be a process which is...
Roger Penrose (58:29.380)
You see, it's very curious
Lex Fridman (58:30.500)
the way the history has developed in quantum mechanics,
Roger Penrose (58:34.140)
because very early on,
Lex Fridman (58:35.460)
people thought there was something to do with consciousness,
Lex Fridman (58:37.780)
but it was almost the other way around.
Lex Fridman (58:39.980)
You see, you have to say the Schrodinger equation
Roger Penrose (58:42.980)
says all these different alternatives happen all at once,
Lex Fridman (58:46.020)
and then when is it that only one of them happens?
Roger Penrose (58:48.540)
Well, one of the views, which was quite commonly held
Lex Fridman (58:50.820)
by a few distinguished quantum physicists,
Roger Penrose (58:53.460)
that's when a conscious being looks at the system
Lex Fridman (58:56.620)
or becomes aware of it,
Lex Fridman (58:57.940)
and at that point, it becomes one or the other.
Lex Fridman (59:01.740)
That's a role where consciousness
Roger Penrose (59:03.700)
is somehow actively reducing the state.
Lex Fridman (59:07.020)
My view is almost the exact opposite of that.
Roger Penrose (59:10.140)
It's the state reduces itself in some way which...
Lex Fridman (59:14.180)
Some noncomputational way which we don't understand,
Roger Penrose (59:17.100)
we don't have a proper theory of,
Lex Fridman (59:19.180)
and that is the building block of what consciousness is.
Lex Fridman (59:24.420)
So consciousness is the other way around.
Lex Fridman (59:26.220)
It depends on that choice which nature makes all the time
Roger Penrose (59:31.220)
when the state becomes one or the other
Lex Fridman (59:33.100)
rather than the superposition of one and the other,
Lex Fridman (59:36.020)
and when that happens, there is what we're saying now,
Lex Fridman (59:39.540)
an element of proto consciousness takes place.
Roger Penrose (59:43.100)
Proto consciousness is, roughly speaking,
Lex Fridman (59:45.620)
the building block out of which
Roger Penrose (59:47.380)
actual consciousness is constructed.
Lex Fridman (59:50.060)
So you have these proto conscious elements,
Roger Penrose (59:53.180)
which are when the state decides
Lex Fridman (59:55.020)
to do one thing or the other,
Lex Fridman (59:57.540)
and that's the thing which when organized together,
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