Lee Smolin: Quantum Gravity and Einstein’s Unfinished Revolution
物理与宇宙学音乐与艺术技术与编程生物与进化历史与文明
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quantumtheoryphysicssciencedonspacefundamentalrealstringbookeinsteinmechanicsgravitycommunityeventsuniversenaturetalkviewprinciples
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🎙️ 完整对话（1382 条）
Lex Fridman (00:00.000)
The following is a conversation with Lee Smolin.
以下是与李·斯莫林的对话。
Lex Fridman (00:02.880)
He's a theoretical physicist,
他是一位理论物理学家，
Lex Fridman (00:04.520)
co inventor of loop quantum gravity,
圈量子引力的共同发明者，
Lex Fridman (00:06.680)
and a contributor of many interesting ideas
以及许多有趣想法的贡献者
Lex Fridman (00:08.860)
to cosmology, quantum field theory,
宇宙学、量子场论、
Lee Smolin (00:11.320)
the foundations of quantum mechanics,
量子力学的基础，
Lex Fridman (00:12.960)
theoretical biology, and the philosophy of science.
理论生物学和科学哲学。
Lee Smolin (00:16.360)
He's the author of several books,
他是多本书的作者
Lex Fridman (00:18.180)
including one that critiques the state of physics
包括批评物理学现状的一个
Lex Fridman (00:21.000)
and string theory called The Trouble with Physics.
弦理论称为“物理学的麻烦”。
Lex Fridman (00:24.080)
And his latest book, Einstein's Unfinished Revolution,
他的最新著作《爱因斯坦未完成的革命》
Lee Smolin (00:27.100)
The Search for What Lies Beyond the Quantum.
寻找量子之外的东西。
Lex Fridman (00:30.240)
He's an outspoken personality in the public debates
他在公开辩论中是一个直言不讳的人
Lee Smolin (00:32.880)
on the nature of our universe,
关于我们宇宙的本质，
Lex Fridman (00:34.600)
among the top minds in the theoretical physics community.
是理论物理学界的顶尖人物之一。
Lee Smolin (00:38.240)
This community has its respected academics,
这个社区有受人尊敬的学者，
Lex Fridman (00:41.000)
its naked emperors, its outcasts and its revolutionaries,
它赤裸裸的皇帝、它的流放者和它的革命者，
Lee Smolin (00:44.440)
its madmen and its dreamers.
它的疯子和它的梦想家。
Lex Fridman (00:46.900)
This is why it's an exciting world to explore
这就是为什么这是一个令人兴奋的探索世界
Lee Smolin (00:49.560)
through a long form conversation.
通过长篇对话。
Lex Fridman (00:51.800)
I recommend you listen back to the episodes
Lee Smolin (00:53.800)
with Leonard Susskind, Sean Carroll, Michio Okaku,
Lex Fridman (00:57.200)
Max Tegmark, Eric Weinstein, and Jim Gates.
Lee Smolin (01:01.200)
You might be asking, why talk to physicists
Lex Fridman (01:03.860)
if you're interested in AI?
Lee Smolin (01:06.160)
To me, creating artificial intelligence systems
Lex Fridman (01:08.800)
requires more than Python and deep learning.
Lee Smolin (01:11.400)
It requires that we return to exploring
Lex Fridman (01:13.360)
the fundamental nature of the universe and the human mind.
Lee Smolin (01:18.520)
Theoretical physicists venture out into the dark,
Lex Fridman (01:21.200)
mysterious, psychologically challenging place
Lee Smolin (01:23.560)
of first principles more than almost any other discipline.
Lex Fridman (01:28.120)
This is the Artificial Intelligence Podcast.
Lee Smolin (01:30.880)
If you enjoy it, subscribe on YouTube,
Lex Fridman (01:33.160)
give it five stars on Apple Podcast,
Lee Smolin (01:34.960)
support it on Patreon, or simply connect with me on Twitter
Lex Fridman (01:38.280)
at Lex Friedman, spelled F R I D M A N.
Lee Smolin (01:42.440)
As usual, I'll do one or two minutes of ads now
Lex Fridman (01:45.320)
and never any ads in the middle
Lee Smolin (01:46.640)
that can break the flow of the conversation.
Lex Fridman (01:48.880)
I hope that works for you
Lex Fridman (01:50.200)
and doesn't hurt the listening experience.
Lex Fridman (01:52.520)
This show is presented by Cash App,
Lee Smolin (01:54.480)
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Lex Fridman (01:56.760)
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Lee Smolin (02:00.200)
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Lex Fridman (02:02.400)
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Lee Smolin (02:04.840)
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Lex Fridman (02:06.760)
Since Cash App allows you to buy Bitcoin,
Lee Smolin (02:09.120)
let me mention that cryptocurrency
Lex Fridman (02:11.360)
in the context of the history of money is fascinating.
Lee Smolin (02:14.640)
I recommend Ascent of Money as a great book on this history.
Lex Fridman (02:18.440)
Debits and credits on ledgers
Lee Smolin (02:20.120)
started around 30,000 years ago.
Lex Fridman (02:23.320)
The US dollar, of course, created over 200 years ago,
Lex Fridman (02:27.000)
and Bitcoin, the first decentralized cryptocurrency,
Lex Fridman (02:30.240)
was released just over 10 years ago.
Lex Fridman (02:32.880)
So given that history, cryptocurrency is still very much
Lex Fridman (02:35.880)
in its early days of development,
Lex Fridman (02:37.920)
but it still is aiming to
Lex Fridman (02:39.560)
and just might redefine the nature of money.
Lee Smolin (02:43.040)
If you get Cash App from the App Store or Google Play
Lex Fridman (02:45.360)
and use the code LEXBODCAST, you'll get $10,
Lex Fridman (02:49.080)
and Cash App will also donate $10 to First,
Lex Fridman (02:51.920)
one of my favorite organizations
Lee Smolin (02:53.720)
that is helping to advance robotics and STEM education
Lex Fridman (02:56.880)
for young people around the world.
Lex Fridman (02:58.880)
And now, here's my conversation with Lee Smolin.
Lex Fridman (03:03.120)
What is real?
Lee Smolin (03:05.120)
Let's start with an easy question.
Lex Fridman (03:06.440)
Put another way, how do we know what is real
Lex Fridman (03:09.160)
and what is merely a creation
Lex Fridman (03:10.680)
of our human perception and imagination?
Lee Smolin (03:14.240)
We don't know.
Lex Fridman (03:15.640)
We don't know.
Lee Smolin (03:16.480)
This is science.
Lex Fridman (03:17.320)
I presume we're talking about science.
Lex Fridman (03:19.960)
And we believe, or I believe,
Lex Fridman (03:24.320)
that there is a world that is independent of my existence
Lex Fridman (03:28.520)
and my experience about it and my knowledge of it,
Lex Fridman (03:32.520)
and this I call the real world.
Lex Fridman (03:35.800)
So you said science, but even bigger than science, what?
Lex Fridman (03:39.120)
Sure, sure.
Lee Smolin (03:40.120)
I need not have said this is science.
Lex Fridman (03:42.400)
I just was warming up.
Lex Fridman (03:44.840)
Warming up?
Lex Fridman (03:46.480)
Okay, now that we're warmed up,
Lee Smolin (03:47.800)
let's take a brief step outside of science.
Lex Fridman (03:51.040)
Is it completely a crazy idea to you
Lee Smolin (03:54.400)
that everything that exists is merely a creation
Lex Fridman (03:57.480)
of our mind?
Lex Fridman (03:58.800)
So there's a few, not many.
Lex Fridman (04:01.880)
This is outside of science now.
Lee Smolin (04:04.200)
People who believe sort of perception
Lex Fridman (04:06.520)
is fundamentally what's in our human perception,
Lee Smolin (04:10.000)
the visual cortex and so on,
Lex Fridman (04:11.720)
the cognitive constructs that's being formed there
Lee Smolin (04:16.240)
is the reality.
Lex Fridman (04:18.040)
And then anything outside is something
Lee Smolin (04:20.320)
that we can never really grasp.
Lex Fridman (04:22.480)
Is that a crazy idea to you?
Lee Smolin (04:24.080)
There's a version of that that is not crazy at all.
Lex Fridman (04:27.760)
What we experience is constructed by our brains
Lex Fridman (04:33.200)
and by our brains in an active mode.
Lex Fridman (04:38.080)
So we don't see the raw world.
Lee Smolin (04:41.920)
We see a very processed world.
Lex Fridman (04:43.800)
We feel something that's very processed through our brains
Lex Fridman (04:47.480)
and our brains are incredible.
Lex Fridman (04:50.120)
But I still believe that behind that experience,
Lee Smolin (04:55.720)
that mirror or veil or whatever you wanna call it,
Lex Fridman (04:59.400)
there is a real world and I'm curious about it.
Lex Fridman (05:02.520)
Can we truly, how do we get a sense of that real world?
Lex Fridman (05:06.720)
Is it through the tools of physics,
Lex Fridman (05:08.600)
from theory to the experiments?
Lex Fridman (05:11.400)
Or can we actually grasp it in some intuitive way
Lex Fridman (05:15.320)
that's more connected to our ape ancestors?
Lex Fridman (05:21.240)
Or is it still fundamentally the tools of math and physics
Lex Fridman (05:25.160)
that really allow us to grasp it?
Lex Fridman (05:26.440)
Well, let's talk about what tools they are.
Lex Fridman (05:29.040)
What you say are the tools of math and physics.
Lex Fridman (05:32.040)
I mean, I think we're in the same position
Lee Smolin (05:34.480)
as our ancestors in the caves
Lex Fridman (05:37.880)
or before the caves or whatever.
Lee Smolin (05:40.160)
We find ourselves in this world and we're curious.
Lex Fridman (05:43.320)
We also, it's important to be able to explain
Lex Fridman (05:47.920)
what happens when there are fires, when there are not fires,
Lex Fridman (05:50.800)
what animals and plants are good to eat and all that stuff.
Lex Fridman (05:56.360)
But we're also just curious.
Lex Fridman (05:57.640)
We look up in the sky and we see the sun and the moon
Lex Fridman (06:01.480)
and the stars and we see some of those move
Lex Fridman (06:03.960)
and we're very curious about that.
Lex Fridman (06:07.160)
And I think we're just naturally curious.
Lex Fridman (06:10.840)
So we make, this is my version of how we work.
Lee Smolin (06:16.120)
We make up stories and explanations.
Lex Fridman (06:20.240)
And where there are two things
Lee Smolin (06:24.080)
which I think are just true of being human,
Lex Fridman (06:27.560)
we make judgments fast because we have to.
Lex Fridman (06:31.040)
Where to survive, is that a tiger or is that not a tiger?
Lex Fridman (06:36.040)
And we go.
Lee Smolin (06:37.400)
Act.
Lex Fridman (06:38.400)
We have to act fast on incomplete information.
Lex Fridman (06:41.120)
So we judge quickly and we're often wrong
Lex Fridman (06:46.000)
or at least sometimes wrong, which is all I need for this.
Lee Smolin (06:49.120)
We're often wrong.
Lex Fridman (06:50.520)
So we fool ourselves and we fool other people readily.
Lex Fridman (06:56.880)
And so there's lots of stories that get told
Lex Fridman (06:59.880)
and some of them result in a concrete benefit
Lex Fridman (07:04.280)
and some of them don't.
Lex Fridman (07:06.880)
So you said we're often wrong,
Lex Fridman (07:09.360)
but what does it mean to be right?
Lex Fridman (07:12.440)
Right, that's an excellent question.
Lee Smolin (07:15.960)
To be right, well since I believe that there is a real world,
Lex Fridman (07:23.000)
I believe that to be, you can challenge me on this
Lee Smolin (07:26.280)
if you're not a realist.
Lex Fridman (07:27.480)
A realist is somebody who believes
Lee Smolin (07:28.960)
in this real objective world
Lex Fridman (07:31.240)
which is independent of our perception.
Lee Smolin (07:33.040)
If I'm a realist, I think that to be right
Lex Fridman (07:38.680)
is to come closer.
Lee Smolin (07:40.200)
I think first of all, there's a relative scale.
Lex Fridman (07:42.200)
There's not right and wrong.
Lee Smolin (07:43.480)
There's right or more right and less right.
Lex Fridman (07:46.920)
And you're more right if you come closer
Lee Smolin (07:49.080)
to an exact true description of that real world.
Lex Fridman (07:53.040)
Now can we know that for sure?
Lee Smolin (07:54.800)
No.
Lex Fridman (07:56.040)
And the scientific method is ultimately
Lex Fridman (07:58.880)
what allows us to get a sense
Lex Fridman (08:00.640)
of how close we're getting to that real world?
Lee Smolin (08:03.000)
No on two counts.
Lex Fridman (08:04.120)
First of all, I don't believe there's a scientific method.
Lee Smolin (08:08.200)
I was very influenced when I was in graduate school
Lex Fridman (08:10.680)
by the writings of Paul Fireman
Lee Smolin (08:12.760)
who was an important philosopher of science
Lex Fridman (08:15.720)
who argued that there isn't a scientific method.
Lex Fridman (08:18.280)
There is or there is not?
Lex Fridman (08:19.840)
There is not.
Lex Fridman (08:20.920)
Can you elaborate, I'm sorry if you were going to,
Lex Fridman (08:23.760)
but can you elaborate on what does it mean
Lee Smolin (08:27.040)
for there not to be a scientific method,
Lex Fridman (08:28.800)
this notion that I think a lot of people believe in
Lex Fridman (08:33.080)
in this day and age?
Lex Fridman (08:34.840)
Sure.
Lee Smolin (08:36.080)
Paul Fireman, he was a student of Popper
Lex Fridman (08:39.760)
who taught Karl Popper.
Lex Fridman (08:42.320)
And Fireman argued both by logic
Lex Fridman (08:48.400)
and by historical example that you name anything
Lee Smolin (08:51.400)
that should be part of the practice of science.
Lex Fridman (08:55.040)
Say you should always make sure that your theories agree
Lee Smolin (08:57.440)
with all the data that's already been taken.
Lex Fridman (09:01.200)
And he'll prove to you that there have to be times
Lee Smolin (09:03.600)
when science contradicts, when some scientist contradicts
Lex Fridman (09:08.120)
that advice for science to progress overall.
Lex Fridman (09:16.880)
So it's not a simple matter.
Lex Fridman (09:18.240)
I think that, I think of science as a community.
Lee Smolin (09:25.200)
Of people.
Lex Fridman (09:26.160)
Of people and as a community of people
Lee Smolin (09:29.120)
bound by certain ethical precepts,
Lex Fridman (09:33.080)
precepts, whatever that is.
Lex Fridman (09:35.000)
So in that community, a set of ideas they operate under,
Lex Fridman (09:40.520)
meaning ethically of kind of the rules of the game
Lee Smolin (09:44.360)
they operate under.
Lex Fridman (09:45.460)
Don't lie, report all your results,
Lee Smolin (09:48.000)
whether they agree or don't agree with your hypothesis.
Lex Fridman (09:52.920)
Check the training of a scientist.
Lee Smolin (09:56.000)
Mostly consists of methods of checking
Lex Fridman (09:59.320)
because again, we make lots of mistakes.
Lee Smolin (10:01.460)
We're very error prone.
Lex Fridman (10:03.680)
But there are tools both on the mathematics side
Lex Fridman (10:06.680)
and the experimental side to check and double check
Lex Fridman (10:09.380)
and triple check.
Lex Fridman (10:11.000)
And a scientist goes through a training
Lex Fridman (10:14.400)
and I think this is part of it.
Lee Smolin (10:16.400)
You can't just walk off the street and say,
Lex Fridman (10:18.280)
yo, I'm a scientist.
Lee Smolin (10:20.640)
You have to go through the training
Lex Fridman (10:22.280)
and the training, the test that lets you be done
Lee Smolin (10:27.560)
with the training is can you form a convincing case
Lex Fridman (10:33.360)
for something that your colleagues
Lee Smolin (10:37.800)
will not be able to shout down
Lex Fridman (10:40.560)
because they'll ask, did you check this?
Lex Fridman (10:42.520)
And did you check that?
Lex Fridman (10:43.400)
And did you check this?
Lex Fridman (10:44.240)
And what about seeming contradiction with this?
Lex Fridman (10:47.720)
And you've got to have answers to all those things
Lee Smolin (10:52.240)
or you don't get taken seriously.
Lex Fridman (10:53.800)
And when you get to the point where you can produce
Lee Smolin (10:56.560)
that kind of defense and argument,
Lex Fridman (10:58.960)
then they give you a PhD.
Lex Fridman (11:02.220)
And you're kind of licensed.
Lex Fridman (11:03.920)
You're still gonna be questioned
Lex Fridman (11:06.000)
and you still may propose or publish mistakes.
Lex Fridman (11:10.640)
But the community is gonna have to waste less time
Lee Smolin (11:14.480)
fixing your mistakes.
Lex Fridman (11:15.840)
Yes, but if you can maybe linger on it a little longer,
Lee Smolin (11:20.240)
what's the gap between the thing that that community does
Lex Fridman (11:25.240)
and the ideal of the scientific method?
Lee Smolin (11:28.800)
The scientific method is you should be able
Lex Fridman (11:31.840)
to repeat and experiment.
Lee Smolin (11:36.320)
There's a lot of elements to what construes
Lex Fridman (11:39.400)
the scientific method, but the final result,
Lee Smolin (11:41.960)
the hope of it is that you should be able to say
Lex Fridman (11:46.720)
with some confidence that a particular thing
Lee Smolin (11:50.160)
is close to the truth.
Lex Fridman (11:53.040)
Right, but there's not a simple relationship
Lee Smolin (11:55.440)
between experiment and hypothesis or theory.
Lex Fridman (11:58.600)
For example, Galileo did this experiment
Lee Smolin (12:01.120)
of dropping a ball from the top of a tower
Lex Fridman (12:04.440)
and it falls right at the base of the tower.
Lex Fridman (12:07.760)
And an Aristotelian would say, wow,
Lex Fridman (12:10.480)
of course it falls right to the base of the tower.
Lee Smolin (12:12.760)
That shows that the earth isn't moving
Lex Fridman (12:14.400)
while the ball is falling.
Lex Fridman (12:16.720)
And Galileo says, no way, there's a principle of inertia
Lex Fridman (12:19.760)
and it has an inertia in the direction
Lee Smolin (12:22.280)
where the earth isn't moving and the tower
Lex Fridman (12:24.360)
and the ball and the earth all move together.
Lee Smolin (12:26.840)
When the principle of inertia tells you it hits the bottom,
Lex Fridman (12:30.080)
it does look, therefore my principle of inertia is right.
Lex Fridman (12:33.000)
And Aristotelian says, no, our style of science is right.
Lex Fridman (12:37.280)
The earth is stationary.
Lex Fridman (12:39.400)
And so you gotta get an interconnected bunch of cases
Lex Fridman (12:45.600)
and work hard to line up and explain.
Lee Smolin (12:49.200)
It took centuries to make the transition
Lex Fridman (12:51.840)
from Aristotelian physics to the new physics.
Lee Smolin (12:55.880)
It wasn't done until Newton in 1680 something, 1687.
Lex Fridman (13:02.000)
So what do you think is the nature of the process
Lex Fridman (13:04.960)
that seems to lead to progress?
Lex Fridman (13:07.960)
If we at least look at the long arc of science,
Lee Smolin (13:11.120)
of all the community of scientists,
Lex Fridman (13:13.360)
they seem to do a better job of coming up with ideas
Lee Smolin (13:16.960)
that engineers can then take on and build rockets with
Lex Fridman (13:21.120)
or build computers with or build cool stuff with.
Lex Fridman (13:26.400)
I don't know, a better job than what?
Lex Fridman (13:30.200)
Than this previous century.
Lex Fridman (13:32.480)
So century by century, we'll talk about string theory
Lex Fridman (13:35.800)
and so on and kind of possible,
Lex Fridman (13:38.040)
what you might think of as dead ends and so on.
Lex Fridman (13:41.040)
Which is not the way I think of string theory.
Lee Smolin (13:42.680)
We'll straighten out, we'll get all the strings straight.
Lex Fridman (13:45.840)
But there is, nevertheless in science, very often,
Lee Smolin (13:49.640)
at least temporary dead ends.
Lex Fridman (13:52.040)
But if you look at the, through centuries,
Lee Smolin (13:57.760)
the century before Newton and the century after Newton,
Lex Fridman (14:01.120)
it seems like a lot of ideas came closer to the truth
Lee Smolin (14:07.080)
that then could be usable by our civilization
Lex Fridman (14:10.280)
to build the iPhone, right?
Lee Smolin (14:12.940)
To build cool things that improve our quality of life.
Lex Fridman (14:15.900)
That's the progress I'm kind of referring to.
Lex Fridman (14:19.400)
Let me, can I say that more precisely?
Lex Fridman (14:21.440)
Yes, well, it's a low bar.
Lee Smolin (14:23.840)
Because I think it's important to get the time places right.
Lex Fridman (14:28.840)
There was a scientific revolution that partly succeeded
Lee Smolin (14:34.640)
between about 1900 or late 1890s
Lex Fridman (14:39.520)
and into the 1930s, 1940s and so.
Lex Fridman (14:45.440)
And maybe some, if you stretched it, into the 1970s.
Lex Fridman (14:50.280)
And the technology, this was the discovery of relativity
Lex Fridman (14:54.520)
and that included a lot of developments of electromagnetism.
Lex Fridman (14:58.320)
The confirmation, which wasn't really well confirmed
Lee Smolin (15:02.600)
into the 20th century, that matter was made of atoms.
Lex Fridman (15:06.560)
And the whole picture of nuclei with electrons going around,
Lee Smolin (15:09.880)
this is early 20th century.
Lex Fridman (15:12.520)
And then quantum mechanics was from 1905,
Lee Smolin (15:17.840)
took a long time to develop, to the late 1920s.
Lex Fridman (15:21.760)
And then it was basically in final form.
Lex Fridman (15:25.280)
And the basis of this partial revolution,
Lex Fridman (15:29.440)
and we can come back to why it's only a partial revolution,
Lee Smolin (15:33.440)
is the basis of the technologies that you mentioned.
Lex Fridman (15:37.040)
All of, I mean, electrical technology
Lee Smolin (15:40.840)
was being developed slowly with this.
Lex Fridman (15:42.880)
And in fact, there's a close relation
Lee Smolin (15:46.000)
between the development of electricity
Lex Fridman (15:49.560)
and the electrification of cities in the United States
Lex Fridman (15:54.120)
and Europe and so forth.
Lex Fridman (15:56.600)
And the development of the science.
Lee Smolin (16:00.800)
The fundamental physics since the early 1970s
Lex Fridman (16:08.520)
doesn't have a story like that so far.
Lee Smolin (16:11.200)
There's not a series of triumphs and progresses
Lex Fridman (16:16.560)
and there's not any practical application.
Lex Fridman (16:19.760)
So just to linger briefly on the early 20th century
Lex Fridman (16:26.520)
and the revolutions in science that happened there,
Lex Fridman (16:30.320)
what was the method by which the scientific community
Lex Fridman (16:33.960)
kept each other in check about when you get something right,
Lex Fridman (16:39.040)
when you get something wrong?
Lex Fridman (16:40.120)
Is experimental validation ultimately the final test?
Lee Smolin (16:43.600)
It's absolutely necessary.
Lex Fridman (16:45.320)
And the key things were all validated.
Lee Smolin (16:47.600)
The key predictions of quantum mechanics
Lex Fridman (16:50.920)
and of the theory of electricity and magnetism.
Lex Fridman (16:54.360)
So before we talk about Einstein, your new book,
Lex Fridman (16:57.800)
before String Theory, Quantum Mechanics, so on,
Lee Smolin (17:00.720)
let's take a step back at a higher level question.
Lex Fridman (17:04.040)
What is that you mentioned?
Lex Fridman (17:06.880)
What is realism?
Lex Fridman (17:08.360)
What is anti realism?
Lex Fridman (17:11.600)
And maybe why do you find realism,
Lex Fridman (17:13.840)
as you mentioned, so compelling?
Lee Smolin (17:15.680)
Well, realism is the belief in an external world
Lex Fridman (17:26.000)
independent of our existence, our perception,
Lee Smolin (17:28.680)
our belief, our knowledge.
Lex Fridman (17:30.720)
A realist as a physicist is somebody who believes
Lee Smolin (17:35.520)
that there should be possible some completely objective
Lex Fridman (17:40.640)
description of each and every process
Lee Smolin (17:44.760)
at the fundamental level, which describes and explains
Lex Fridman (17:49.400)
exactly what happens and why it happens.
Lee Smolin (17:52.800)
That kind of implies that that system,
Lex Fridman (17:55.680)
in a realist view, is deterministic,
Lee Smolin (17:58.280)
meaning there's no fuzzy magic going on
Lex Fridman (18:01.120)
that you can never get to the bottom,
Lee Smolin (18:02.280)
or you can get to the bottom of anything
Lex Fridman (18:04.280)
and perfectly describe it.
Lee Smolin (18:07.640)
Some people would say that I'm not that interested
Lex Fridman (18:10.720)
in determinism, but I could live with the fundamental world,
Lee Smolin (18:15.560)
which had some chance in it.
Lex Fridman (18:18.560)
So do you, you said you could live with it,
Lex Fridman (18:21.760)
but do you think God plays dice in our universe?
Lex Fridman (18:26.520)
I think it's probably much worse than that.
Lex Fridman (18:30.360)
In which direction?
Lex Fridman (18:32.080)
I think that theories can change,
Lex Fridman (18:33.920)
and theories can change without warning.
Lex Fridman (18:36.120)
I think the future is open.
Lex Fridman (18:38.520)
You mean the fundamental laws of physics can change?
Lex Fridman (18:40.920)
Yeah.
Lee Smolin (18:42.440)
Oh, okay, we'll get there.
Lex Fridman (18:43.800)
I thought we would be able to find some solid ground,
Lex Fridman (18:49.720)
but apparently the entirety of it, temporarily so, probably.
Lex Fridman (18:55.160)
Okay, so realism is the idea that while the ground
Lee Smolin (19:00.760)
is solid, you can describe it.
Lex Fridman (19:02.920)
What's the role of the human being,
Lex Fridman (19:04.680)
our beautiful, complex human mind in realism?
Lex Fridman (19:10.480)
Do we have a, are we just another set of molecules
Lee Smolin (19:14.760)
connected together in a clever way,
Lex Fridman (19:16.480)
or the observer, does the observer, our human mind,
Lee Smolin (19:22.120)
consciousness, have a role in this realism view
Lex Fridman (19:24.760)
of the physical universe?
Lee Smolin (19:27.200)
There's two ways, there's two questions you could be asking.
Lex Fridman (19:30.400)
One, does our conscious mind, do our perceptions
Lee Smolin (19:35.680)
play a role in making things become,
Lex Fridman (19:38.800)
in making things real or things becoming?
Lee Smolin (19:42.280)
That's question one.
Lex Fridman (19:43.320)
Question two is, does this, we can call it
Lee Smolin (19:47.400)
a naturalist view of the world that is based on realism,
Lex Fridman (19:54.720)
allow a place to understand the existence of
Lex Fridman (19:58.080)
and the nature of perceptions and consciousness in mind,
Lex Fridman (1:00:00.200)
of string theory.
Lex Fridman (1:00:01.840)
And then Andy found there was a way
Lex Fridman (1:00:04.620)
to put a certain kind of mathematical curvature
Lee Smolin (1:00:07.480)
called torsion into the solutions.
Lex Fridman (1:00:10.440)
And he wrote a paper, String Theory with Torsion,
Lee Smolin (1:00:13.860)
in which he discovered there was,
Lex Fridman (1:00:15.940)
and not formally uncountable,
Lex Fridman (1:00:20.180)
but he was unable to invent any way
Lex Fridman (1:00:22.220)
to count the number of solutions
Lee Smolin (1:00:24.580)
or classify the diverse solutions.
Lex Fridman (1:00:27.480)
And he wrote that this is worrying
Lee Smolin (1:00:31.100)
because doing phenomenology the old fashioned way
Lex Fridman (1:00:33.900)
by solving the theory is not gonna work
Lee Smolin (1:00:37.420)
because there's gonna be loads of solutions
Lex Fridman (1:00:41.100)
for every proposed phenomenology
Lee Smolin (1:00:42.940)
for anything the experiments discovered.
Lex Fridman (1:00:45.220)
And it hasn't quite worked out that way.
Lex Fridman (1:00:47.500)
But nonetheless, he took that worry to me.
Lex Fridman (1:00:51.700)
We spoke at least once, maybe two or three times about that.
Lex Fridman (1:00:56.660)
And I got seriously worried about that.
Lex Fridman (1:01:00.020)
And this is just a little.
Lex Fridman (1:01:02.460)
So it's like an anecdote that inspired
Lex Fridman (1:01:05.020)
your worry about string theory in general?
Lee Smolin (1:01:07.280)
Well, I tried to solve the problem
Lex Fridman (1:01:10.100)
and I tried to solve the problem.
Lee Smolin (1:01:12.960)
I was reading at that time, a lot of biology,
Lex Fridman (1:01:15.740)
a lot of evolutionary theory,
Lee Smolin (1:01:17.300)
like Linmar Gullis and Steve Gould and so forth.
Lex Fridman (1:01:23.100)
And I could take your time to go through the things,
Lex Fridman (1:01:29.740)
but it occurred to me,
Lex Fridman (1:01:30.580)
maybe physics was like evolutionary biology
Lex Fridman (1:01:33.980)
and maybe the laws evolved.
Lex Fridman (1:01:36.060)
And there was, the biologists talk about a landscape,
Lee Smolin (1:01:40.060)
a fitness landscape of DNA sequences
Lex Fridman (1:01:44.040)
or protein sequences or species or something like that.
Lex Fridman (1:01:48.780)
And I took their concept and the word landscape
Lex Fridman (1:01:51.340)
from theoretical biology and made a scenario
Lee Smolin (1:01:54.540)
about how the universe as a whole could evolve
Lex Fridman (1:01:59.060)
to discover the parameters of the standard model.
Lex Fridman (1:02:03.540)
And I'm happy to discuss,
Lex Fridman (1:02:04.620)
that's called cosmological natural selection.
Lee Smolin (1:02:07.220)
Cosmological natural selection.
Lex Fridman (1:02:09.900)
Yeah.
Lee Smolin (1:02:10.740)
Wow, so the parameters of the standard model,
Lex Fridman (1:02:12.580)
so the laws of physics are changing.
Lee Smolin (1:02:15.540)
This idea would say that the laws of physics
Lex Fridman (1:02:18.940)
are changing in some way that echoes
Lee Smolin (1:02:23.420)
that of natural selection,
Lex Fridman (1:02:24.900)
or just it adjusts in some way towards some goal.
Lee Smolin (1:02:28.860)
Yes.
Lex Fridman (1:02:30.000)
And I published that,
Lee Smolin (1:02:33.660)
I wrote the paper in 1888 or 89,
Lex Fridman (1:02:36.620)
the paper was published in 92.
Lee Smolin (1:02:39.140)
My first book in 1997,
Lex Fridman (1:02:40.980)
The Life of the Cosmos was explicitly about that.
Lex Fridman (1:02:45.500)
And I was very clear that what was important
Lex Fridman (1:02:49.300)
is that because you would develop an ensemble of universes,
Lex Fridman (1:02:55.020)
but they were related by descent to natural selection,
Lex Fridman (1:03:00.580)
almost every universe would share the property
Lee Smolin (1:03:03.500)
that it was, its fitness was maximized to some extent,
Lex Fridman (1:03:08.500)
or at least close to maximum.
Lex Fridman (1:03:10.920)
And I could deduce predictions
Lex Fridman (1:03:12.480)
that could be tested from that.
Lex Fridman (1:03:16.080)
And I worked all of that out
Lex Fridman (1:03:18.220)
and I compared it to the anthropic principle
Lee Smolin (1:03:20.440)
where you weren't able to make tests
Lex Fridman (1:03:23.320)
or make falsifications.
Lee Smolin (1:03:24.480)
All of this was in the late 80s and early 90s.
Lex Fridman (1:03:28.400)
That's a really compelling notion,
Lex Fridman (1:03:30.000)
but how does that help you arrive?
Lex Fridman (1:03:32.840)
I'm coming to where the book came from.
Lee Smolin (1:03:36.040)
Yes.
Lex Fridman (1:03:37.000)
So what got me,
Lee Smolin (1:03:41.080)
I worked on string theory.
Lex Fridman (1:03:42.720)
I also worked on loop quantum gravity.
Lex Fridman (1:03:47.480)
And I was one of the inventors of loop quantum gravity.
Lex Fridman (1:03:50.640)
And because of my strong belief in some other principles,
Lee Smolin (1:03:55.480)
which led to this notion of wanting a quantum theory
Lex Fridman (1:03:58.040)
of gravity to be what we call relational
Lee Smolin (1:04:00.880)
or background independent,
Lex Fridman (1:04:03.020)
I tried very hard to make string theory
Lee Smolin (1:04:05.960)
background independent.
Lex Fridman (1:04:07.600)
And it ended up developing a bunch of tools
Lee Smolin (1:04:09.840)
which then could apply directly to general relativity
Lex Fridman (1:04:12.600)
and that became loop quantum gravity.
Lex Fridman (1:04:15.020)
So the things were very closely related
Lex Fridman (1:04:17.280)
and have always been very closely related in my mind.
Lee Smolin (1:04:20.440)
The idea that there were two communities,
Lex Fridman (1:04:22.160)
one devoted to strings and one devoted to loops is nuts
Lex Fridman (1:04:25.320)
and has always been nuts.
Lex Fridman (1:04:28.900)
Okay, so anyway, there's this nuts community
Lee Smolin (1:04:32.680)
of loops and strings that are all beautiful
Lex Fridman (1:04:35.000)
and compelling and mathematically speaking.
Lex Fridman (1:04:37.400)
And what's the trouble with all that?
Lex Fridman (1:04:38.800)
Why is that such a problem?
Lex Fridman (1:04:40.680)
So I was interested in developing that notion
Lex Fridman (1:04:45.620)
of how science works based on a community
Lex Fridman (1:04:47.820)
and ethics that I told you about.
Lex Fridman (1:04:50.800)
And I wrote a draft of a book about that,
Lee Smolin (1:04:54.780)
which had several chapters on methodology of science.
Lex Fridman (1:04:58.860)
And it was a rather academically oriented book.
Lex Fridman (1:05:02.520)
And those chapters were the first part of the book,
Lex Fridman (1:05:06.560)
the first third of it.
Lex Fridman (1:05:07.680)
And you didn't find their remnants
Lex Fridman (1:05:09.880)
in what's now the last part of the trouble with physics.
Lex Fridman (1:05:14.520)
And then I described a number of test cases, case studies.
Lex Fridman (1:05:18.680)
And one of them, which I knew was the search
Lee Smolin (1:05:21.480)
for quantum gravity and string theory and so forth.
Lex Fridman (1:05:25.200)
And I wasn't able to get that book published.
Lex Fridman (1:05:28.660)
So somebody made the suggestion of flipping it around
Lex Fridman (1:05:34.700)
and starting with a story of string theory,
Lee Smolin (1:05:36.820)
which was already controversial.
Lex Fridman (1:05:38.620)
This was 2004, 2005.
Lex Fridman (1:05:42.460)
But I was very careful to be detailed,
Lex Fridman (1:05:48.540)
to criticize papers and not people.
Lee Smolin (1:05:52.900)
You won't find me criticizing individuals.
Lex Fridman (1:05:55.540)
You'll find me criticizing certain writing.
Lex Fridman (1:05:59.100)
But in any case, here's what I regret.
Lex Fridman (1:06:03.820)
Let me make your program worthwhile.
Lee Smolin (1:06:06.500)
Yes.
Lex Fridman (1:06:07.340)
As far as I know, with the exception of not understanding
Lex Fridman (1:06:11.980)
how large the applications to condensed matter,
Lex Fridman (1:06:15.380)
say ADS CFT would get,
Lee Smolin (1:06:20.380)
I think largely my diagnosis of string theory
Lex Fridman (1:06:26.580)
as it was then has stood up since 2006.
Lex Fridman (1:06:31.260)
What I regret is that the same critique,
Lex Fridman (1:06:34.940)
I was using string theory as an example,
Lex Fridman (1:06:37.540)
and the same critique applies to many other communities
Lex Fridman (1:06:41.780)
in science and all of, including,
Lex Fridman (1:06:44.380)
and this is where I regret my own community,
Lex Fridman (1:06:46.500)
that is a community of people working on quantum gravity.
Lee Smolin (1:06:49.900)
Not science string theory.
Lex Fridman (1:06:52.220)
But, and I considered saying that explicitly.
Lex Fridman (1:06:55.860)
But to say that explicitly,
Lex Fridman (1:06:57.220)
since it's a small, intimate community,
Lee Smolin (1:07:00.460)
I would be telling stories and naming names
Lex Fridman (1:07:04.100)
and making a kind of history
Lee Smolin (1:07:06.420)
that I have no right to write.
Lex Fridman (1:07:08.900)
So I stayed away from that, but was misunderstood.
Lex Fridman (1:07:12.060)
But if I may ask, is there a hopeful message
Lex Fridman (1:07:16.380)
for theoretical physics that we can take from that book,
Lee Smolin (1:07:20.260)
sort of that looks at the community,
Lex Fridman (1:07:22.100)
not just your own work on,
Lee Smolin (1:07:24.780)
now with causality and nonlocality,
Lex Fridman (1:07:26.780)
but just broadly in understanding
Lee Smolin (1:07:29.060)
the fundamental nature of our reality,
Lex Fridman (1:07:32.060)
what's your hope for the 21st century in physics?
Lee Smolin (1:07:37.060)
Well, that we solve the problem.
Lex Fridman (1:07:39.660)
That we solve the unfinished problem of Einstein's.
Lee Smolin (1:07:44.300)
That's certainly the thing that I care about most in.
Lex Fridman (1:07:47.940)
Hope for most.
Lee Smolin (1:07:49.180)
Let me say one thing.
Lex Fridman (1:07:50.620)
Among the young people that I work with,
Lee Smolin (1:07:53.740)
I hear very often and sense a total disinterest
Lex Fridman (1:07:59.220)
in these arguments that we older scientists have.
Lex Fridman (1:08:03.420)
And an interest in what each other is doing.
Lex Fridman (1:08:05.820)
And this is starting to appear in conferences
Lee Smolin (1:08:09.860)
where the young people interested in quantum gravity
Lex Fridman (1:08:13.300)
make a conference, they invite loops and strings
Lex Fridman (1:08:16.300)
and causal dynamical triangulations and causal set people.
Lex Fridman (1:08:20.540)
And we're having a conference like this next week,
Lee Smolin (1:08:24.060)
a small workshop at perimeter.
Lex Fridman (1:08:26.980)
And I guess I'm advertising this.
Lex Fridman (1:08:28.380)
And then in the summer,
Lex Fridman (1:08:30.500)
we're having a big full on conference,
Lee Smolin (1:08:33.460)
which is just quantum gravity.
Lex Fridman (1:08:34.900)
It's not strings, it's not loops.
Lex Fridman (1:08:37.260)
But the organizers and the speakers
Lex Fridman (1:08:39.420)
will be from all the different communities.
Lex Fridman (1:08:41.780)
And this to me is very helpful.
Lex Fridman (1:08:45.580)
That the different ideas are coming together.
Lee Smolin (1:08:49.020)
At least people are expressing an interest in that.
Lex Fridman (1:08:54.020)
It's a huge honor talking to you, Lee.
Lee Smolin (1:08:56.300)
Thanks so much for your time today.
Lex Fridman (1:08:57.700)
Thank you.
Lee Smolin (1:08:59.180)
Thanks for listening to this conversation.
Lex Fridman (1:09:01.300)
And thank you to our presenting sponsor, Cash App.
Lee Smolin (1:09:04.180)
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Lex Fridman (1:09:06.820)
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Lee Smolin (1:09:09.580)
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Lex Fridman (1:09:12.820)
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Lee Smolin (1:09:16.260)
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Lex Fridman (1:09:19.060)
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Lee Smolin (1:09:20.900)
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Lex Fridman (1:09:23.340)
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Lex Fridman (1:09:27.260)
And now let me leave you with some words from Lee Smolin.
Lex Fridman (1:09:31.300)
One possibility is God is nothing but
Lee Smolin (1:09:35.340)
the power of the universe to organize itself.
Lex Fridman (1:09:39.580)
Thanks for listening and hope to see you next time.
Lex Fridman (20:01.760)
and that's question two.
Lex Fridman (20:04.080)
Question two, I do think a lot about,
Lex Fridman (20:06.640)
and my answer, which is not an answer, is I hope so,
Lex Fridman (20:11.120)
but it certainly doesn't yet.
Lex Fridman (20:14.000)
So what kind?
Lex Fridman (20:14.840)
Question one, I don't think so.
Lex Fridman (20:17.000)
But of course, the answer to question one
Lex Fridman (20:18.720)
depends on question two.
Lee Smolin (20:20.120)
Right.
Lex Fridman (20:21.760)
So I'm not up to question one yet.
Lex Fridman (20:24.040)
So question two is the thing that you can kind of
Lex Fridman (20:26.160)
struggle with at this time.
Lee Smolin (20:27.720)
Yes.
Lex Fridman (20:28.560)
That's, what about the anti realists?
Lex Fridman (20:32.120)
So what flavor, what are the different camps
Lex Fridman (20:36.280)
of anti realists that you've talked about?
Lee Smolin (20:38.440)
I think it would be nice if you can articulate
Lex Fridman (20:42.480)
for the people for whom there is not
Lee Smolin (20:44.160)
a very concrete real world, or there's divisions,
Lex Fridman (20:47.520)
or it's messier than the realist view of the universe,
Lex Fridman (20:52.280)
what are the different camps, what are the different views?
Lex Fridman (20:54.680)
I'm not sure I'm a good scholar and can talk about
Lee Smolin (20:58.160)
the different camps and analyze it,
Lex Fridman (20:59.960)
but some, many of the inventors of quantum physics
Lee Smolin (21:04.560)
were not realists, were anti realists.
Lex Fridman (21:07.600)
Their scholars, they lived in a very perilous time
Lee Smolin (21:11.000)
between the two world wars.
Lex Fridman (21:13.800)
And there were a lot of trends in culture
Lee Smolin (21:17.480)
which were going that way.
Lex Fridman (21:19.240)
But in any case, they said things like,
Lee Smolin (21:21.960)
the purpose of science is not to give an objective
Lex Fridman (21:27.360)
realist description of nature as it would be
Lee Smolin (21:29.360)
in our absence.
Lex Fridman (21:30.680)
This might be saying Niels Bohr.
Lee Smolin (21:33.040)
The purpose of science is as an extension
Lex Fridman (21:36.320)
of our conversations with each other
Lee Smolin (21:38.760)
to describe our interactions with nature.
Lex Fridman (21:41.280)
And we're free to invent and use terms like
Lee Smolin (21:44.640)
particle, or wave, or causality, or time, or space.
Lex Fridman (21:48.760)
If they're useful to us, and they carry some
Lee Smolin (21:53.960)
intuitive implication, but we shouldn't believe
Lex Fridman (21:58.000)
that they actually have to do with what nature
Lee Smolin (22:00.280)
would be like in our absence,
Lex Fridman (22:02.520)
which we have nothing to say about.
Lex Fridman (22:05.440)
Do you find any aspect of that,
Lex Fridman (22:08.120)
because you kind of said that we human beings
Lee Smolin (22:10.400)
tell stories, do you find aspects of that
Lex Fridman (22:13.920)
kind of anti realist view of Niels Bohr compelling?
Lee Smolin (22:18.800)
That we fundamentally are storytellers,
Lex Fridman (22:20.960)
and then we create tools of space, and time,
Lex Fridman (22:24.520)
and causality, and whatever this fun quantum
Lex Fridman (22:28.520)
mechanic stuff is to help us tell the story of our world.
Lee Smolin (22:32.800)
Sure, I just would like to believe that there's
Lex Fridman (22:35.560)
an aspiration for the other thing.
Lex Fridman (22:39.680)
The other thing being what?
Lex Fridman (22:41.400)
The realist point of view.
Lex Fridman (22:44.000)
Do you hope that the stories will eventually lead us
Lex Fridman (22:47.320)
to discovering the real world as it is?
Lee Smolin (22:56.560)
Yeah.
Lex Fridman (22:57.560)
Is perfection possible, by the way?
Lee Smolin (22:59.200)
Is it? No.
Lex Fridman (23:00.680)
Well that's, you mean will we ever get there
Lex Fridman (23:03.880)
and know that we're there?
Lex Fridman (23:05.200)
Yeah, exactly.
Lee Smolin (23:06.480)
That's not my, that's for people 5,000 years in the future.
Lex Fridman (23:09.800)
We're certainly nowhere near there yet.
Lex Fridman (23:14.240)
Do you think reality that exists outside of our mind,
Lex Fridman (23:20.720)
do you think there's a limit to our cognitive abilities?
Lee Smolin (23:24.680)
Is, again, descendants of apes,
Lex Fridman (23:26.840)
who are just biological systems,
Lee Smolin (23:28.840)
is there a limit to our mind's capability
Lex Fridman (23:31.800)
to actually understand reality?
Lee Smolin (23:35.880)
Sort of, there comes a point,
Lex Fridman (23:39.200)
even with the help of the tools of physics,
Lee Smolin (23:42.360)
that we just cannot grasp some fundamental aspects
Lex Fridman (23:46.440)
of that reality.
Lee Smolin (23:47.280)
Again, I think that's a question
Lex Fridman (23:48.240)
for 5,000 years in the future.
Lee Smolin (23:49.840)
We're not even close to that limit.
Lex Fridman (23:51.160)
I think there is a universality.
Lee Smolin (23:54.240)
Here, I don't agree with David Deutsch about everything,
Lex Fridman (23:56.920)
but I admire the way he put things in his last book.
Lex Fridman (24:01.280)
And he talked about the role of explanation.
Lex Fridman (24:04.600)
And he talked about the universality of certain languages
Lee Smolin (24:08.880)
or the universality of mathematics
Lex Fridman (24:11.040)
or of computing and so forth.
Lex Fridman (24:15.760)
And he believed that universality,
Lex Fridman (24:18.400)
which is something real,
Lee Smolin (24:19.360)
which somehow comes out of the fact
Lex Fridman (24:22.880)
that a symbolic system or a mathematical system
Lee Smolin (24:26.160)
can refer to itself and can,
Lex Fridman (24:29.040)
I forget what that's called,
Lee Smolin (24:30.160)
can reference back to itself and build,
Lex Fridman (24:34.360)
in which he argued for a universality of possibility
Lee Smolin (24:38.320)
for our understanding, whatever is out there.
Lex Fridman (24:41.360)
But I admire that argument,
Lex Fridman (24:45.280)
but it seems to me we're doing okay so far,
Lex Fridman (24:51.040)
but we'll have to see.
Lee Smolin (24:53.840)
Whether there is a limit or not.
Lex Fridman (24:55.160)
For now, we've got plenty to play with.
Lee Smolin (24:57.240)
Yeah.
Lex Fridman (24:58.320)
There are things which are right there in front of us
Lee Smolin (25:01.760)
which we miss.
Lex Fridman (25:03.640)
And I'll quote my friend, Eric Weinstein,
Lee Smolin (25:06.840)
in saying, look, Einstein carried his luggage.
Lex Fridman (25:10.520)
Freud carried his luggage.
Lee Smolin (25:12.040)
Marx carried his luggage.
Lex Fridman (25:13.400)
Martha Graham carried her luggage, et cetera.
Lee Smolin (25:17.000)
Edison carried his luggage.
Lex Fridman (25:19.240)
All these geniuses carried their luggage.
Lex Fridman (25:22.000)
And not once before relatively recently
Lex Fridman (25:25.640)
did it occur to anybody to put a wheel on luggage
Lex Fridman (25:28.160)
and pull it.
Lex Fridman (25:29.000)
And it was right there waiting to be invented
Lee Smolin (25:33.040)
for centuries.
Lex Fridman (25:34.600)
So this is Eric Weinstein.
Lee Smolin (25:37.960)
Yeah.
Lex Fridman (25:39.040)
What do the wheels represent?
Lee Smolin (25:40.520)
Are you basically saying that there's stuff
Lex Fridman (25:42.200)
right in front of our eyes?
Lee Smolin (25:43.760)
That once we, it just clicks,
Lex Fridman (25:46.200)
we put the wheels on the luggage,
Lee Smolin (25:48.240)
a lot of things will fall into place.
Lex Fridman (25:49.880)
Yes, I do, I do.
Lex Fridman (25:52.440)
And every day I wake up and think,
Lex Fridman (25:55.120)
why can't I be that guy who was walking through the airport?
Lex Fridman (26:00.760)
What do you think it takes to be that guy?
Lex Fridman (26:02.840)
Because like you said,
Lee Smolin (26:05.760)
a lot of really smart people carried their luggage.
Lex Fridman (26:10.040)
What, just psychologically speaking,
Lex Fridman (26:12.440)
so Eric Weinstein is a good example of a person
Lex Fridman (26:14.560)
who thinks outside the box.
Lee Smolin (26:16.120)
Yes.
Lex Fridman (26:16.960)
Who resists almost conventional thinking.
Lee Smolin (26:21.040)
You're an example of a person who by habit,
Lex Fridman (26:25.480)
by psychology, by upbringing, I don't know,
Lex Fridman (26:28.880)
but resists conventional thinking as well,
Lex Fridman (26:31.160)
just by nature.
Lee Smolin (26:32.000)
Thank you, that's a compliment.
Lex Fridman (26:32.920)
That's a compliment?
Lee Smolin (26:34.080)
Good.
Lex Fridman (26:34.920)
So what do you think it takes to do that?
Lex Fridman (26:37.240)
Is that something you were just born with?
Lex Fridman (26:40.880)
I doubt it.
Lee Smolin (26:42.040)
Well, from my studying some cases,
Lex Fridman (26:47.040)
because I'm curious about that, obviously,
Lex Fridman (26:49.840)
and just in a more concrete way,
Lex Fridman (26:52.520)
when I started out in physics,
Lee Smolin (26:54.400)
because I started a long way from physics,
Lex Fridman (26:57.880)
so it took me a long, not a long time,
Lex Fridman (27:00.800)
but a lot of work to get to study it and get into it,
Lex Fridman (27:04.280)
so I did wonder about that.
Lex Fridman (27:07.040)
And so I read the biographies,
Lex Fridman (27:10.400)
and in fact, I started with the autobiography of Einstein
Lex Fridman (27:12.960)
and Newton and Galileo and all those people.
Lex Fridman (27:18.520)
And I think there's a couple of things.
Lee Smolin (27:22.760)
Some of it is luck, being in the right place
Lex Fridman (27:24.920)
at the right time.
Lee Smolin (27:26.320)
Some of it is stubbornness and arrogance,
Lex Fridman (27:28.800)
which can easily go wrong.
Lee Smolin (27:30.440)
Yes.
Lex Fridman (27:31.960)
And I know all of these are doorways.
Lee Smolin (27:36.280)
If you go through them slightly at the wrong speed
Lex Fridman (27:38.960)
or in the wrong angle, they're ways to fail.
Lex Fridman (27:45.000)
But if you somehow have the right luck,
Lex Fridman (27:47.640)
the right confidence or arrogance, caring,
Lee Smolin (27:52.040)
I think Einstein cared to understand nature
Lex Fridman (27:56.000)
with ferocity and a commitment that exceeded
Lee Smolin (28:00.960)
other people of his time.
Lex Fridman (28:02.240)
So he asked more stubborn questions.
Lee Smolin (28:05.080)
He asked deeper questions.
Lex Fridman (28:09.960)
I think, and there's a level of ability
Lex Fridman (28:15.000)
and whether ability is born in or can be developed
Lex Fridman (28:20.120)
to the extent to which it can be developed,
Lee Smolin (28:21.720)
like any of these things like musical talent.
Lex Fridman (28:24.480)
So you mentioned ego.
Lex Fridman (28:27.040)
What's the role of ego in that process?
Lex Fridman (28:29.000)
Confidence.
Lee Smolin (28:30.040)
Confidence.
Lex Fridman (28:30.880)
But in your own life, have you found yourself
Lee Smolin (28:34.680)
walking that nice edge of too much or too little,
Lex Fridman (28:38.920)
so being overconfident and therefore
Lee Smolin (28:41.000)
leaning yourself astray or not sufficiently confident
Lex Fridman (28:43.960)
to throw away the conventional thinking
Lex Fridman (28:47.000)
of whatever the theory of the day, of theoretical physics?
Lex Fridman (28:51.480)
I don't know if I, I mean, I've contributed
Lee Smolin (28:54.240)
where I've contributed, whether if I had had
Lex Fridman (28:57.360)
more confidence in something, I would have gotten further.
Lee Smolin (29:01.360)
I don't know.
Lex Fridman (29:03.960)
Certainly, I'm sitting here at this moment
Lee Smolin (29:09.520)
with very much my own approach to nearly everything.
Lex Fridman (29:14.480)
And I'm calm, I'm happy about that.
Lex Fridman (29:18.800)
But on the other hand, I know people
Lex Fridman (29:20.840)
whose self confidence vastly exceeds mine.
Lex Fridman (29:26.680)
And sometimes I think it's justified
Lex Fridman (29:28.560)
and sometimes I think it's not justified.
Lee Smolin (29:33.040)
Your most recent book titled
Lex Fridman (29:35.280)
Einstein's Unfinished Revolution.
Lex Fridman (29:37.800)
So I have to ask, what is Einstein's unfinished revolution
Lex Fridman (29:42.240)
and also how do we finish it?
Lee Smolin (29:45.480)
Well, that's something I've been trying to do my whole life,
Lex Fridman (29:48.440)
but Einstein's unfinished revolution
Lee Smolin (29:51.240)
is the twin revolutions which invented relativity theory,
Lex Fridman (29:54.880)
special and especially general relativity,
Lex Fridman (29:58.200)
and quantum theory, which he was the first person
Lex Fridman (30:01.320)
to realize in 1905 that there would have to be
Lee Smolin (30:04.960)
a radically different theory which somehow realized
Lex Fridman (30:09.920)
or resolved the paradox of the duality
Lee Smolin (30:12.240)
of particle and wave for photons.
Lex Fridman (30:14.360)
And he was, I mean, people I think don't always
Lee Smolin (30:18.720)
associate Einstein with quantum mechanics
Lex Fridman (30:21.160)
because I think his connection with it,
Lee Smolin (30:24.320)
founding as one of the founders,
Lex Fridman (30:27.080)
I would say, of quantum mechanics,
Lee Smolin (30:28.440)
he kind of put it in the closet.
Lex Fridman (30:30.480)
Is it?
Lee Smolin (30:31.320)
Well, he didn't believe that the quantum mechanics
Lex Fridman (30:34.000)
as it was developed in the mid to late 1920s
Lee Smolin (30:38.160)
was completely correct.
Lex Fridman (30:39.560)
At first, he didn't believe it at all.
Lee Smolin (30:42.160)
Then he was convinced that it's consistent,
Lex Fridman (30:44.180)
but incomplete, and that also is my view.
Lee Smolin (30:47.280)
It needs, for various reasons, I can elucidate,
Lex Fridman (30:52.040)
to have additional degrees of freedom, particles,
Lee Smolin (30:56.960)
forces, something to reach the stage
Lex Fridman (31:00.680)
where it gives a complete description of each phenomenon,
Lee Smolin (31:03.960)
as I was saying, realism demands.
Lex Fridman (31:07.620)
So what aspect of quantum mechanics
Lex Fridman (31:10.320)
bothers you and Einstein the most?
Lex Fridman (31:12.920)
Is it some aspect of the wave function collapse discussions,
Lex Fridman (31:18.240)
the measurement problem?
Lex Fridman (31:19.880)
Is it the?
Lee Smolin (31:23.220)
The measurement problem.
Lex Fridman (31:24.120)
I'm not gonna speak for Einstein.
Lex Fridman (31:26.160)
But the measurement problem, basically, and the fact that.
Lex Fridman (31:31.880)
What is the measurement problem, sorry?
Lee Smolin (31:34.120)
The basic formulation of quantum mechanics
Lex Fridman (31:36.840)
gives you two ways to evolve situations in time.
Lee Smolin (31:41.100)
One of them is explicitly when no observer is observing
Lex Fridman (31:44.920)
and no measurement is taking place.
Lex Fridman (31:47.200)
And the other is when a measurement
Lex Fridman (31:48.720)
or an observation is taking place.
Lex Fridman (31:50.480)
And they basically contradict each other.
Lex Fridman (31:53.960)
But there's another reason why the revolution
Lee Smolin (31:56.720)
was incomplete, which is we don't understand
Lex Fridman (31:58.680)
the relationship between these two parts.
Lee Smolin (32:01.200)
General relativity, which became our best theory
Lex Fridman (32:04.680)
of space and time and gravitation and cosmology,
Lex Fridman (32:08.720)
and quantum theory.
Lex Fridman (32:11.600)
So for the most part, general relativity
Lee Smolin (32:14.120)
describes big things.
Lex Fridman (32:15.960)
Quantum theory describes little things.
Lex Fridman (32:18.080)
And that's the revolution that we found
Lex Fridman (32:20.360)
really powerful tools to describe
Lee Smolin (32:22.520)
big things and little things.
Lex Fridman (32:24.040)
And it's unfinished because we have
Lee Smolin (32:27.400)
two totally separate things and we need to figure out
Lex Fridman (32:30.120)
how to connect them so we can describe everything.
Lee Smolin (32:32.360)
Right, and we either do that if we believe quantum mechanics
Lex Fridman (32:36.820)
as understood now is correct by bringing general relativity
Lee Smolin (32:42.120)
or some extension of general relativity
Lex Fridman (32:44.160)
that describes gravity and so forth
Lee Smolin (32:46.520)
into the quantum domain that's called quantize,
Lex Fridman (32:50.640)
the theory of gravity.
Lee Smolin (32:52.960)
Or if you believe with Einstein
Lex Fridman (32:55.840)
that quantum mechanics needs to be completed,
Lex Fridman (32:58.200)
and this is my view, then part of the job
Lex Fridman (33:03.080)
of finding the right completion
Lee Smolin (33:04.880)
or extension of quantum mechanics
Lex Fridman (33:07.120)
would be one that incorporated space, time, and gravity.
Lex Fridman (33:12.640)
So, where do we begin?
Lex Fridman (33:14.960)
So first, let me ask, perhaps you can give me a chance,
Lee Smolin (33:19.620)
if I could ask you some just really basic questions.
Lex Fridman (33:22.100)
Well, they're not at all.
Lee Smolin (33:23.520)
The basic questions are the hardest,
Lex Fridman (33:24.880)
but you mentioned space, time.
Lex Fridman (33:26.740)
What is space, time?
Lex Fridman (33:28.880)
Space, time, you talked about a construction.
Lex Fridman (33:32.260)
So I believe the space, time is an intellectual construction
Lex Fridman (33:36.440)
that we make of the events in the universe.
Lee Smolin (33:39.200)
I believe the events are real,
Lex Fridman (33:40.680)
and the relationships between the events,
Lee Smolin (33:43.520)
which cause which are real.
Lex Fridman (33:45.720)
But the idea that there's a four dimensional
Lee Smolin (33:50.480)
smooth geometry which has a metric and a connection
Lex Fridman (33:54.000)
and satisfies the equations that Einstein wrote,
Lee Smolin (33:57.320)
it's a good description to some scale.
Lex Fridman (34:00.400)
It's a good approximation, it captures some
Lee Smolin (34:02.760)
of what's really going on in nature.
Lex Fridman (34:05.080)
But I don't believe it for a minute is fundamental.
Lee Smolin (34:08.600)
So, okay, we're gonna allow me to linger on that.
Lex Fridman (34:12.420)
So the universe has events, events cause other events.
Lee Smolin (34:16.760)
This is the idea of causality.
Lex Fridman (34:19.080)
Okay, so that's real.
Lee Smolin (34:22.080)
That's in my.
Lex Fridman (34:23.720)
In your view is real.
Lee Smolin (34:25.520)
Or hypothesis, or the theories that I have been working
Lex Fridman (34:29.660)
to develop make that assumption.
Lex Fridman (34:32.200)
So space, time, you said four dimensional space
Lex Fridman (34:35.320)
is kind of the location of things,
Lex Fridman (34:37.220)
and time is whatever the heck time is.
Lex Fridman (34:42.240)
And you're saying that space, time is,
Lex Fridman (34:47.800)
both space and time are emergent and not fundamental?
Lex Fridman (34:51.480)
No.
Lee Smolin (34:52.320)
Sorry, before you correct me,
Lex Fridman (34:55.460)
what does it mean to be fundamental or emergent?
Lee Smolin (34:58.600)
Fundamental means it's part of the description
Lex Fridman (35:01.480)
as far down as you go.
Lee Smolin (35:03.140)
We have this notion.
Lex Fridman (35:03.980)
As real.
Lee Smolin (35:04.800)
Yes.
Lex Fridman (35:05.640)
As real as real it could be.
Lee Smolin (35:07.240)
Yeah, so I think that time is fundamental,
Lex Fridman (35:10.160)
and quote goes all the way down,
Lex Fridman (35:12.440)
and space does not, and the combination of them
Lex Fridman (35:16.080)
we use in general relativity that we call space time
Lee Smolin (35:18.960)
also does not.
Lex Fridman (35:20.800)
But what is time then?
Lee Smolin (35:24.080)
I think that time, the activity of time
Lex Fridman (35:29.440)
is a continual creation of events from existing events.
Lex Fridman (35:34.360)
So if there's no events, there's no time.
Lex Fridman (35:37.560)
Then there's not only no time, there's no nothing.
Lex Fridman (35:41.060)
So I believe the universe has a history
Lex Fridman (35:47.020)
which goes to the past.
Lee Smolin (35:48.760)
I believe the future does not exist.
Lex Fridman (35:51.700)
There's a notion of the present
Lex Fridman (35:53.320)
and a notion of the past,
Lex Fridman (35:55.520)
and the past consists of,
Lee Smolin (35:58.720)
is a story about events that took place to our past.
Lex Fridman (36:03.640)
So you said the future doesn't exist.
Lee Smolin (36:05.520)
Yes.
Lex Fridman (36:08.800)
Could you say that again?
Lex Fridman (36:10.200)
Can you try to give me a chance to understand that
Lex Fridman (36:14.360)
one more time?
Lex Fridman (36:15.280)
So events cause other events.
Lex Fridman (36:18.480)
What is this universe?
Lee Smolin (36:19.400)
Cause we'll talk about locality and nonlocality.
Lex Fridman (36:23.580)
Good.
Lee Smolin (36:25.120)
Cause it's a crazy, I mean it's not crazy,
Lex Fridman (36:27.120)
it's a beautiful set of ideas that you propose.
Lee Smolin (36:32.160)
But, and if Kozali is fundamental,
Lex Fridman (36:34.640)
I'd just like to understand it better.
Lex Fridman (36:37.120)
What is the past?
Lex Fridman (36:38.920)
What is the future?
Lex Fridman (36:40.000)
What is the flow of time?
Lex Fridman (36:42.760)
Even the error of time in our universe, in your view.
Lex Fridman (36:46.680)
And maybe what's an event, right?
Lex Fridman (36:50.440)
Oh, an event is where something changes,
Lee Smolin (36:54.360)
or where two,
Lex Fridman (36:59.520)
it's hard to say because it's a primitive concept.
Lee Smolin (37:02.200)
An event is a moment of time within space.
Lex Fridman (37:07.960)
This is the view in general relativity,
Lee Smolin (37:11.480)
where two particles intersect in their paths,
Lex Fridman (37:15.480)
or something changes in the path of a particle.
Lee Smolin (37:19.760)
Now, we are postulating that there is,
Lex Fridman (37:23.600)
at the fundamental level, a notion,
Lee Smolin (37:25.600)
which is an elementary notion,
Lex Fridman (37:27.240)
so it doesn't have a definition in terms of other things,
Lex Fridman (37:31.480)
but it is something elementary happening.
Lex Fridman (37:34.800)
And it doesn't have a connection to energy,
Lex Fridman (37:36.920)
or matter, or exchange of energy?
Lex Fridman (37:38.240)
It does have a connection to energy and matter.
Lex Fridman (37:40.160)
So it's at that level.
Lex Fridman (37:41.700)
Yeah, it involves,
Lex Fridman (37:43.280)
and that's why the version of a theory of events
Lex Fridman (37:48.320)
that I've developed with Marina Cortez,
Lex Fridman (37:50.840)
and it's, by the way, I wanna mention my collaborators,
Lex Fridman (37:54.040)
because they've been at least as important
Lee Smolin (37:55.920)
in this work as I have.
Lex Fridman (37:57.800)
It's Marina Cortez in all the work since about 2013,
Lee Smolin (38:02.920)
2012, 2013, about causality, causal sets.
Lex Fridman (38:07.440)
And in the period before that, Roberta Mangibera Unger,
Lee Smolin (38:11.200)
who is a philosopher and a professor of law.
Lex Fridman (38:14.760)
And that's in your efforts,
Lee Smolin (38:16.560)
together with your collaborators,
Lex Fridman (38:17.760)
to finish the unfinished revolution.
Lee Smolin (38:20.120)
Yes.
Lex Fridman (38:20.940)
And focus on causality as a fundamental.
Lee Smolin (38:23.560)
Yes.
Lex Fridman (38:24.400)
As fundamental to physics.
Lee Smolin (38:26.520)
So.
Lex Fridman (38:28.080)
And there's certainly other people we've worked with,
Lex Fridman (38:30.400)
but those two people's thinking
Lex Fridman (38:32.720)
had a huge influence on my own thinking.
Lex Fridman (38:34.920)
So in the way you describe causality,
Lex Fridman (38:36.800)
that's what you mean of time being fundamental.
Lee Smolin (38:39.480)
That causality is fundamental.
Lex Fridman (38:41.560)
Yes.
Lex Fridman (38:43.640)
And what does it mean for space to not be fundamental,
Lex Fridman (38:47.320)
to be emergent?
Lee Smolin (38:48.160)
That's very good.
Lex Fridman (38:48.980)
There's a level of description in which there are events,
Lee Smolin (38:52.600)
there are events create other events,
Lex Fridman (38:58.160)
but there's no space.
Lee Smolin (38:59.280)
They don't live in space.
Lex Fridman (39:00.720)
They have an order in which they caused each other.
Lex Fridman (39:04.000)
And that is part of the nature of time for us.
Lex Fridman (39:07.560)
But there is an emergent approximate description.
Lex Fridman (39:13.720)
And you asked me to define emergent.
Lex Fridman (39:15.560)
I didn't.
Lee Smolin (39:17.160)
An emergent property is a property
Lex Fridman (39:22.400)
that arises at some level of complexity,
Lee Smolin (39:26.480)
larger than and more complex than the fundamental level,
Lex Fridman (39:31.240)
which requires some property to describe it,
Lee Smolin (39:36.120)
which is not directly
Lex Fridman (39:40.600)
explicable or derivable is the word I want
Lee Smolin (39:44.600)
from the properties of the fundamental things.
Lex Fridman (39:48.640)
And space is one of those things
Lee Smolin (39:50.800)
in a sufficiently complex universe,
Lex Fridman (39:53.120)
space, three dimensional position of things emerged.
Lee Smolin (39:58.280)
Yes, and we have this,
Lex Fridman (39:59.880)
we saw how this happens in detail in some models,
Lee Smolin (40:03.920)
both computationally and analytically.
Lex Fridman (40:07.640)
Okay, so connected to space is the idea of locality.
Lee Smolin (40:11.240)
Yes.
Lex Fridman (40:13.360)
So we've talked about realism.
Lex Fridman (40:15.200)
So I live in this world that like sports.
Lex Fridman (40:21.520)
Locality is a thing that you can affect things close to you
Lex Fridman (40:26.280)
and don't have an effect on things that are far away.
Lex Fridman (40:29.800)
It's the thing that bothers me about gravity in general
Lee Smolin (40:32.880)
or action at a distance.
Lex Fridman (40:35.120)
Same thing that probably bothered Newton,
Lee Smolin (40:37.400)
or at least he said a little bit about it.
Lex Fridman (40:43.880)
Okay, so what do you think about locality?
Lex Fridman (40:45.560)
Is it just a construct?
Lex Fridman (40:48.720)
Is it us humans just like this idea
Lex Fridman (40:51.680)
and are connected to it because we exist in it,
Lex Fridman (40:54.200)
we need it for our survival, but it's not fundamental?
Lee Smolin (40:57.120)
I mean, it seems crazy for it not to be
Lex Fridman (40:58.920)
a fundamental aspect of our reality.
Lee Smolin (41:01.920)
It does.
Lex Fridman (41:03.040)
Can you comfort me on a sort of as a therapist,
Lex Fridman (41:05.920)
like how do I?
Lex Fridman (41:07.840)
I'm not a good therapist, but I'll do my best.
Lee Smolin (41:10.400)
Okay.
Lex Fridman (41:13.440)
There are several different definitions of locality
Lee Smolin (41:16.800)
when you come to talk about locality in physics.
Lex Fridman (41:20.720)
In quantum field theory,
Lee Smolin (41:23.680)
which is a mixture of special relativity
Lex Fridman (41:27.520)
and quantum mechanics,
Lee Smolin (41:29.640)
there is a precise definition of locality.
Lex Fridman (41:33.840)
Field operators corresponding to events in space time,
Lee Smolin (41:37.560)
which are space like separated,
Lex Fridman (41:38.960)
commute with each other as operators.
Lex Fridman (41:41.480)
So in quantum mechanics,
Lex Fridman (41:43.520)
you think about the nature of reality as fields
Lex Fridman (41:46.200)
and things that are close in a field
Lex Fridman (41:48.800)
have an impact on each other more than farther away.
Lee Smolin (41:53.000)
That's, yes.
Lex Fridman (41:54.200)
That's very comforting.
Lee Smolin (41:55.560)
That makes sense.
Lex Fridman (41:56.400)
So that's a property of quantum field theory
Lex Fridman (41:58.400)
and it's well tested.
Lex Fridman (42:00.320)
Unfortunately, there's another definition of local,
Lee Smolin (42:04.920)
which was expressed by Einstein
Lex Fridman (42:07.680)
and expressed more precisely by John Bell,
Lee Smolin (42:11.080)
which has been tested experimentally and found to fail.
Lex Fridman (42:15.720)
And this set up is you take two particles.
Lex Fridman (42:19.600)
So one thing that's really weird about quantum mechanics
Lex Fridman (42:24.000)
is a property called entanglement.
Lee Smolin (42:26.480)
You can have two particles interact
Lex Fridman (42:28.880)
and then share a property
Lee Smolin (42:31.200)
without it being a property
Lex Fridman (42:32.680)
of either one of the two particles.
Lex Fridman (42:35.400)
And if you take such a system
Lex Fridman (42:38.480)
and then you make a measurement on particle A,
Lee Smolin (42:43.440)
which is over here on my right side,
Lex Fridman (42:46.040)
and particle B, which is over here.
Lee Smolin (42:48.200)
Somebody else makes a measurement of particle B.
Lex Fridman (42:50.760)
You can ask that whatever is the real reality
Lee Smolin (42:56.840)
of particle B, it not be affected by the choice
Lex Fridman (43:01.960)
the observer at particle A makes about what to measure,
Lee Smolin (43:04.680)
not the outcome,
Lex Fridman (43:06.160)
just the choice of the different things they might measure.
Lex Fridman (43:09.680)
And that's a notion of locality
Lex Fridman (43:11.400)
because it assumes that these things
Lee Smolin (43:13.240)
are very far spaced like separated.
Lex Fridman (43:16.080)
And it's gonna take a while for any information
Lee Smolin (43:19.040)
about the choice made by the people here at A
Lex Fridman (43:22.160)
to affect the reality at B.
Lex Fridman (43:24.080)
But you make that assumption,
Lex Fridman (43:25.480)
that's called Bell locality.
Lex Fridman (43:27.600)
And you derive a certain inequality
Lex Fridman (43:30.120)
that some correlations,
Lee Smolin (43:32.400)
functions of correlations have to satisfy.
Lex Fridman (43:36.040)
And then you can test that pretty directly
Lee Smolin (43:39.360)
in experiments which create pairs of photons
Lex Fridman (43:42.280)
or other particles.
Lex Fridman (43:44.000)
And it's wrong by many sigma.
Lex Fridman (43:46.800)
In experiment, it doesn't match.
Lex Fridman (43:49.920)
So what does that mean?
Lex Fridman (43:51.840)
That means that that definition of locality
Lee Smolin (43:54.600)
I stated is false.
Lex Fridman (43:56.440)
The one that Einstein was playing with.
Lee Smolin (43:58.840)
Yeah, and the one that I stated,
Lex Fridman (44:00.720)
that is it's not true that whatever is real
Lee Smolin (44:04.760)
about particle B is unaffected by the choice
Lex Fridman (44:08.720)
that the observer makes as to what to measure
Lee Smolin (44:10.960)
in particle A.
Lex Fridman (44:12.200)
No matter how long they've been propagating
Lee Smolin (44:14.600)
at almost the speed of light or the speed of light
Lex Fridman (44:17.640)
away from each other, it's no matter.
Lex Fridman (44:19.360)
So like the distance between them.
Lex Fridman (44:22.000)
Well, it's been tested, of course,
Lee Smolin (44:23.640)
if you want to have hope for quantum mechanics
Lex Fridman (44:27.560)
being incomplete or wrong and corrected
Lee Smolin (44:30.320)
by something that changes this.
Lex Fridman (44:32.440)
It's been tested over a number of kilometers.
Lee Smolin (44:35.880)
I don't remember whether it's 25 kilometers
Lex Fridman (44:39.440)
or a hundred and something kilometers, but.
Lex Fridman (44:42.160)
So in trying to solve the unsolved revolution,
Lex Fridman (44:47.800)
in trying to come up with the theory for everything,
Lex Fridman (44:50.200)
is causality fundamental and breaking away from locality?
Lex Fridman (44:57.600)
Absolutely.
Lee Smolin (44:59.400)
A crucial step.
Lex Fridman (45:00.480)
So in your book, essentially, those are the two things
Lee Smolin (45:04.080)
we really need to think about as a community.
Lex Fridman (45:07.880)
Especially the physics community has to think about this.
Lex Fridman (45:12.120)
I guess my question is, how do we solve?
Lex Fridman (45:15.680)
How do we finish the unfinished revolution?
Lee Smolin (45:19.120)
Well, that's, I can only tell you what I'm trying to do
Lex Fridman (45:22.760)
and what I've abandoned as not working.
Lee Smolin (45:27.880)
As one ant, smart ant in an ant colony.
Lex Fridman (45:31.440)
Yep.
Lex Fridman (45:32.760)
Or maybe dumb, that's why, who knows?
Lex Fridman (45:35.960)
But anyway, my view of the,
Lee Smolin (45:40.280)
we've had some nice theories invented.
Lex Fridman (45:45.040)
There's a bunch of different ones.
Lee Smolin (45:47.240)
Both relate to quantum mechanics,
Lex Fridman (45:49.640)
relate to quantum gravity.
Lee Smolin (45:51.920)
There's a lot to admire
Lex Fridman (45:53.920)
in many of these different approaches.
Lex Fridman (45:56.800)
But to my understanding,
Lex Fridman (45:58.480)
they, none of them completely solve the problems
Lee Smolin (46:02.840)
that I care about.
Lex Fridman (46:05.480)
And so we're in a situation
Lee Smolin (46:08.040)
which is either terrifying for a student
Lex Fridman (46:11.800)
or full of opportunity for the right student,
Lee Smolin (46:14.920)
in which we've got more than a dozen attempts.
Lex Fridman (46:19.560)
And I never thought, I don't think anybody anticipated
Lee Smolin (46:22.120)
it would work out this way.
Lex Fridman (46:23.640)
Which work partly and then at some point,
Lee Smolin (46:26.640)
they have an issue that nobody can figure out
Lex Fridman (46:28.840)
how to go around or how to solve.
Lex Fridman (46:31.920)
And that's the situation we're in.
Lex Fridman (46:36.080)
My reaction to that is twofold.
Lee Smolin (46:39.520)
One of them is to try to bring people,
Lex Fridman (46:42.640)
we evolved into this unfortunate sociological situation
Lee Smolin (46:46.920)
in which there are communities
Lex Fridman (46:48.800)
around some of these approaches.
Lex Fridman (46:50.680)
And to borrow again, a metaphor from Eric,
Lex Fridman (46:53.720)
they sit on top of hills in the landscape of theories
Lex Fridman (46:58.000)
and throw rocks at each other.
Lex Fridman (47:00.360)
And as Eric says, we need two things.
Lee Smolin (47:02.840)
We need people to get off their hills
Lex Fridman (47:05.400)
and come down into the valleys and party and talk
Lex Fridman (47:08.680)
and become friendly and learn to say,
Lex Fridman (47:14.120)
not no but, but yes and yes.
Lee Smolin (47:18.200)
Your idea goes this far,
Lex Fridman (47:19.640)
but maybe if we put it together with my idea,
Lee Smolin (47:21.800)
we can go further.
Lex Fridman (47:22.920)
Yes.
Lex Fridman (47:25.160)
So in that spirit, I've talked several times
Lex Fridman (47:29.280)
with Sean Carroll, who's also written
Lee Smolin (47:32.680)
an excellent book recently.
Lex Fridman (47:34.200)
And he kind of, he plays around,
Lee Smolin (47:36.880)
is a big fan of the many worlds interpretation
Lex Fridman (47:39.000)
of quantum mechanics.
Lex Fridman (47:40.400)
So I'm a troublemaker.
Lex Fridman (47:42.960)
So let me ask, what's your sense of Sean
Lex Fridman (47:47.280)
and the idea of many worlds interpretation?
Lex Fridman (47:50.000)
I've read many the commentary back and forth.
Lee Smolin (47:52.760)
You guys are friendly, respect each other,
Lex Fridman (47:55.800)
but have a lot of fun debating.
Lee Smolin (47:57.400)
I love Sean and he, no, I really,
Lex Fridman (48:02.280)
he's articulate and he's a great representative
Lee Smolin (48:07.920)
or ambassador of science to the public
Lex Fridman (48:10.280)
and for different fields of science to each other.
Lee Smolin (48:14.280)
He also, like I do, takes philosophy seriously.
Lex Fridman (48:19.440)
And unlike what I do in all cases,
Lee Smolin (48:24.360)
he has really done the homework.
Lex Fridman (48:26.440)
He's read a lot, he knows the people,
Lee Smolin (48:29.120)
he talks to them, he exposes his arguments to them.
Lex Fridman (48:34.320)
And I, there's this mysterious thing
Lee Smolin (48:37.520)
that we so often end up on the opposite sides
Lex Fridman (48:40.680)
of one of these issues.
Lee Smolin (48:41.800)
It's fun though.
Lex Fridman (48:43.080)
It's fun and I'd love to have a conversation about that,
Lex Fridman (48:47.720)
but I would want to include him.
Lex Fridman (48:50.120)
I see, about many worlds, well.
Lee Smolin (48:52.160)
No, I can tell you what I think about many worlds.
Lex Fridman (48:54.080)
I'd love to, but actually on that, let me pause.
Lee Smolin (48:56.160)
Sean has a podcast.
Lex Fridman (48:57.360)
You should definitely figure out how to talk to Sean.
Lee Smolin (49:00.000)
I would, I actually told Sean,
Lex Fridman (49:01.720)
I would love to hear you guys just going back and forth.
Lex Fridman (49:05.040)
So I hope you can make that happen eventually,
Lex Fridman (49:07.520)
you and Sean.
Lee Smolin (49:08.360)
I won't tell you what it is,
Lex Fridman (49:09.560)
but there's something that Sean said to me
Lee Smolin (49:12.120)
in June of 2016 that changed my whole approach to a problem.
Lex Fridman (49:17.240)
But I'll have to tell him first.
Lee Smolin (49:19.240)
Yes, and that, that'll be great to tell him on his podcast.
Lex Fridman (49:23.280)
So.
Lee Smolin (49:24.120)
I can't invite myself to his podcast.
Lex Fridman (49:26.280)
But I told him, yeah, okay, we'll make it happen.
Lex Fridman (49:28.560)
So many worlds.
Lex Fridman (49:30.000)
Anyway.
Lex Fridman (49:31.720)
What's your view?
Lex Fridman (49:32.560)
Many worlds, we talk about nonlocality.
Lee Smolin (49:34.840)
Many worlds is also a very uncomfortable idea
Lex Fridman (49:39.800)
or beautiful depending on your perspective.
Lee Smolin (49:43.400)
It's very nice in terms of,
Lex Fridman (49:49.000)
I mean, there's a realist aspect to it.
Lee Smolin (49:50.600)
I think you called it magical realism.
Lex Fridman (49:52.560)
Yeah.
Lee Smolin (49:53.400)
It's just a beautiful line.
Lex Fridman (49:55.720)
But at the same time,
Lee Smolin (49:57.800)
it's very difficult to far limited human minds
Lex Fridman (50:00.640)
to comprehend.
Lex Fridman (50:01.480)
So what are your thoughts about it?
Lex Fridman (50:04.960)
Let me start with the easy and obvious
Lex Fridman (50:08.640)
and then go to the scientific.
Lex Fridman (50:10.760)
Okay.
Lee Smolin (50:12.280)
It doesn't appeal to me.
Lex Fridman (50:13.520)
It doesn't answer the questions that I want answered.
Lex Fridman (50:17.720)
And it does so to such a strong case
Lex Fridman (50:20.480)
that when Roberto Mangueber Anger and I
Lee Smolin (50:23.280)
began looking for principles,
Lex Fridman (50:24.960)
and I want to come back and talk about
Lee Smolin (50:26.440)
the use of principles in science,
Lex Fridman (50:28.640)
because that's the other thing I was going to say,
Lex Fridman (50:30.240)
and I don't want to lose that.
Lex Fridman (50:32.560)
When we started looking for principles,
Lee Smolin (50:34.720)
we made our first principle,
Lex Fridman (50:36.040)
there is just one world and it happens once.
Lex Fridman (50:39.960)
But so it's not helpful to my personal approach,
Lex Fridman (50:47.160)
to my personal agenda,
Lex Fridman (50:49.120)
but of course I'm part of a community.
Lex Fridman (50:51.400)
And my sense of the many worlds interpretation,
Lee Smolin (50:57.040)
I have thought a lot about it and struggled a lot with it,
Lex Fridman (51:00.800)
is the following.
Lee Smolin (51:05.320)
First of all, there's Everett himself,
Lex Fridman (51:07.840)
there's what's in Everett.
Lex Fridman (51:10.600)
And there are several issues there
Lex Fridman (51:13.560)
connected with the derivation of the Born Rule,
Lee Smolin (51:16.880)
which is the rule that gives probabilities to events.
Lex Fridman (51:20.960)
And the reasons why there is a problem with probability
Lee Smolin (51:25.440)
is that I mentioned the two ways
Lex Fridman (51:28.480)
that physical systems can evolve.
Lee Smolin (51:31.280)
The many worlds interpretation cuts off,
Lex Fridman (51:34.440)
one, the one having to do with measurement,
Lex Fridman (51:37.120)
and just has the other one, the Schrodinger evolution,
Lex Fridman (51:39.760)
which is this smooth evolution of the quantum state.
Lex Fridman (51:44.000)
But the notion of probability is only in the second rule,
Lex Fridman (51:48.720)
which we've thrown away.
Lex Fridman (51:50.840)
So where does probability come from?
Lex Fridman (51:52.600)
And you have to answer the question
Lee Smolin (51:54.960)
because experimentalists use probabilities
Lex Fridman (51:57.720)
to check the theory.
Lee Smolin (52:00.400)
Now, at first sight, you get very confused
Lex Fridman (52:05.040)
because there seems to be a real problem
Lee Smolin (52:07.520)
because in the many worlds interpretation,
Lex Fridman (52:10.960)
this talk about branches is not quite precise,
Lex Fridman (52:13.480)
but I'll use it.
Lex Fridman (52:16.360)
There's a branch in which everything that might happen
Lee Smolin (52:19.240)
does happen with probability one in that branch.
Lex Fridman (52:23.880)
You might think you could count the number of branches
Lee Smolin (52:27.440)
in which things do and don't happen
Lex Fridman (52:30.280)
and get numbers that you can define
Lee Smolin (52:32.360)
as something like frequentist probabilities.
Lex Fridman (52:35.760)
And Everett did have an argument in that direction,
Lex Fridman (52:41.120)
but the argument gets very subtle
Lex Fridman (52:43.280)
when there are an infinite number of possibilities,
Lee Smolin (52:45.800)
as is the case in most quantum systems.
Lex Fridman (52:49.000)
And my understanding,
Lee Smolin (52:50.600)
although I'm not as much of an expert as some other people,
Lex Fridman (52:54.840)
is that Everett's own proposal failed, did not work.
Lee Smolin (53:00.760)
There are then, but it doesn't stop there.
Lex Fridman (53:05.480)
There is an important idea that Everett didn't know about,
Lee Smolin (53:08.560)
which is decoherence,
Lex Fridman (53:10.000)
and it is a phenomenon that might be very much relevant.
Lex Fridman (53:13.680)
And so a number of people post Everett
Lex Fridman (53:19.080)
have tried to make versions of what you might call
Lee Smolin (53:22.280)
many worlds quantum mechanics.
Lex Fridman (53:26.160)
And this is a big area and it's subtle,
Lex Fridman (53:29.640)
and it's not the kind of thing that I do well.
Lex Fridman (53:33.080)
So I consulted, that's why there's two chapters on this
Lee Smolin (53:36.200)
in the book I wrote.
Lex Fridman (53:37.560)
Chapter 10, which is about Everett's version,
Lee Smolin (53:39.680)
chapter 11, there's a very good group of philosophers
Lex Fridman (53:44.600)
of physics in Oxford, Simon Saunders, David Wallace,
Lee Smolin (53:49.440)
Harvey Brown, and a number of others.
Lex Fridman (53:52.800)
And of course there's David Deutsch, who is there.
Lex Fridman (53:57.120)
And those people have developed and put a lot of work
Lex Fridman (54:01.480)
into a very sophisticated set of ideas
Lee Smolin (54:04.280)
designed to come back and answer that question.
Lex Fridman (54:07.560)
They have the flavor of there are really no probabilities,
Lee Smolin (54:11.400)
we admit that, but imagine if the Everett story was true
Lex Fridman (54:15.720)
and you were living in that multiverse,
Lex Fridman (54:18.760)
how would you make bets?
Lex Fridman (54:20.960)
And so they use decision theory
Lee Smolin (54:24.640)
from the theory of probability and gambling and so forth
Lex Fridman (54:28.640)
to shape a story of how you would bet
Lee Smolin (54:33.040)
if you were inside an Everett in the universe
Lex Fridman (54:35.400)
and you knew that.
Lex Fridman (54:37.800)
And there's a debate among those experts
Lex Fridman (54:41.920)
as to whether they or somebody else has really succeeded.
Lex Fridman (54:47.560)
And when I checked in as I was finishing the book
Lex Fridman (54:50.760)
with some of those people, like Simon,
Lee Smolin (54:52.800)
who's a good friend of mine, and David Wallace,
Lex Fridman (54:56.600)
they told me that they weren't sure
Lee Smolin (54:59.240)
that any of them was yet correct.
Lex Fridman (55:02.160)
So that's what I put in my book.
Lee Smolin (55:04.840)
Now, to add to that, Sean has his own approach
Lex Fridman (55:08.160)
to that problem in what's called self referencing
Lee Smolin (55:10.720)
or self locating observers.
Lex Fridman (55:14.640)
And it doesn't, I tried to read it
Lex Fridman (55:20.240)
and it didn't make sense to me,
Lex Fridman (55:22.520)
but I didn't study it hard,
Lee Smolin (55:24.120)
I didn't communicate with Sean,
Lex Fridman (55:25.480)
I didn't do the things that I would do,
Lex Fridman (55:27.000)
so I had nothing to say about it in the book.
Lex Fridman (55:30.680)
I don't know whether it's right or not.
Lee Smolin (55:32.800)
Let's talk a little bit about science.
Lex Fridman (55:36.520)
You mentioned the use of principles in science.
Lex Fridman (55:40.920)
What does it mean to have a principle
Lex Fridman (55:43.080)
and why is that important?
Lee Smolin (55:45.360)
When I feel very frustrated about quantum gravity,
Lex Fridman (55:48.440)
I like to go back and read history.
Lex Fridman (55:51.840)
And of course, Einstein, his achievements
Lex Fridman (55:55.160)
are a huge lesson and hopefully something
Lee Smolin (55:59.840)
like a role model.
Lex Fridman (56:00.840)
And it's very clear that Einstein thought
Lee Smolin (56:05.200)
that the first job when you wanna enter a new domain
Lex Fridman (56:09.080)
of theoretical physics is to discover and invent principles
Lex Fridman (56:13.400)
and then make models of how those principles
Lex Fridman (56:15.880)
might be applied in some experimental situation,
Lee Smolin (56:19.280)
which is where the mathematics comes in.
Lex Fridman (56:22.440)
So for Einstein, there was no unified space and time.
Lee Smolin (56:27.440)
Minkowski invented this idea of space time.
Lex Fridman (56:30.760)
For Einstein, it was a model of his principles
Lee Smolin (56:33.760)
or his postulates.
Lex Fridman (56:36.120)
And I've taken the view that we don't know
Lee Smolin (56:41.280)
the principles of quantum gravity.
Lex Fridman (56:43.440)
I can think about candidates and I have some papers
Lee Smolin (56:46.920)
where I discuss different candidates
Lex Fridman (56:50.120)
and I'm happy to discuss them.
Lex Fridman (56:52.520)
But my belief now is that those partially successful
Lex Fridman (56:56.840)
approaches are all models,
Lee Smolin (57:01.680)
which might describe indeed some quantum gravity physics
Lex Fridman (57:05.880)
in some domain, in some aspect,
Lex Fridman (57:08.960)
but ultimately would be important
Lex Fridman (57:12.720)
because they model the principles
Lex Fridman (57:15.200)
and the first job is to tie down those principles.
Lex Fridman (57:18.200)
So that's the approach that I'm taking.
Lex Fridman (57:21.280)
So speaking of principles, in your 2006 book,
Lex Fridman (57:26.240)
The Trouble with Physics, you criticized a bit
Lee Smolin (57:30.920)
string theory for taking us away from the rigors
Lex Fridman (57:34.160)
of the scientific method or whatever you would call it.
Lex Fridman (57:37.120)
But what's the trouble with physics today
Lex Fridman (57:42.760)
and how do we fix it?
Lex Fridman (57:44.240)
Can I say how I read that book?
Lex Fridman (57:47.400)
Sure.
Lee Smolin (57:48.240)
Because I, and I'm not, this of course has to be my fault
Lex Fridman (57:52.440)
because you can't as an author claim
Lee Smolin (57:55.680)
after all the work you put in that you are misread.
Lex Fridman (57:59.480)
But I will say that many of the reviewers
Lee Smolin (58:04.600)
who are not personally involved
Lex Fridman (58:06.520)
and even many who were working on string theory
Lee Smolin (58:09.720)
or some other approach to quantum gravity
Lex Fridman (58:12.400)
told me, communicated with me and told me
Lee Smolin (58:14.360)
they thought that I was fair
Lex Fridman (58:17.360)
and balance was the word that was usually used.
Lex Fridman (58:20.840)
So let me tell you what my purpose was in writing that book,
Lex Fridman (58:24.040)
which clearly got diverted by,
Lee Smolin (58:28.760)
because there was already a rather hot argument going on.
Lex Fridman (58:35.160)
And this is.
Lex Fridman (58:36.000)
On which topic?
Lex Fridman (58:36.840)
On string theory specifically?
Lex Fridman (58:38.600)
Or in general in physics?
Lex Fridman (58:41.060)
No, more specifically than string theory.
Lex Fridman (58:44.060)
So since we're in Cambridge, can I say that?
Lex Fridman (58:47.680)
We're doing this in Cambridge.
Lee Smolin (58:48.520)
Yeah, yeah, of course.
Lex Fridman (58:49.360)
Cambridge, just to be clear, Massachusetts.
Lex Fridman (58:52.680)
And on Harvard campus.
Lex Fridman (58:55.600)
Right, so Andy Straminger is a good friend of mine
Lex Fridman (59:00.600)
and has been for many, many years.
Lex Fridman (59:03.460)
And Andy, so originally there was this beautiful idea
Lee Smolin (59:09.440)
that there were five string theories
Lex Fridman (59:11.360)
and maybe they would be unified into one.
Lex Fridman (59:14.420)
And we would discover a way to break that symmetries
Lex Fridman (59:18.520)
of one of those string theories
Lex Fridman (59:20.640)
and discover the standard model
Lex Fridman (59:22.760)
and predict all the properties
Lee Smolin (59:24.560)
of standard model particles,
Lex Fridman (59:26.280)
like their masses and charges and so forth,
Lee Smolin (59:28.960)
coupling constants.
Lex Fridman (59:31.560)
And then there was a bunch of solutions
Lee Smolin (59:35.840)
to string theory found,
Lex Fridman (59:37.240)
which led each of them to a different version
Lee Smolin (59:39.700)
of particle physics with a different phenomenology.
Lex Fridman (59:42.680)
These are called the Calabi Yao manifolds,
Lee Smolin (59:46.560)
named after Yao, who is also here.
Lex Fridman (59:50.280)
Not, certainly we've been friends
Lee Smolin (59:52.440)
at some time in the past anyway.
Lex Fridman (59:55.400)
And then there were, nobody was sure,
Lex Fridman (59:57.880)
but hundreds of thousands of different versions
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