# Annotated captions of Murray Gell-Mann on beauty and truth in physics in English

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tedtalks |
00:00 00:04 |
Thank you for putting up these pictures of my colleagues over here. |

tedtalks |
00:04 00:09 |
(Laughter) We'll be talking about them. |

tedtalks |
00:09 00:14 |
Now, I'm going try an experiment. I don't do experiments, normally. I'm a theorist. |

tedtalks |
00:14 00:18 |
But I'm going see what happens if I press this button. |

tedtalks |
00:18 00:23 |
Sure enough. OK. I used to work in this field of elementary particles. |

tedtalks |
00:23 00:27 |
What happens to matter if you chop it up very fine? |

tedtalks |
00:27 00:29 |
What is it made of? |

tedtalks |
00:29 00:34 |
And the laws of these particles are valid throughout the universe, |

tedtalks |
00:34 00:37 |
and they're very much connected with the history of the universe. |

tedtalks |
00:37 00:40 |
We know a lot about four forces. There must be a lot more, |

tedtalks |
00:40 00:42 |
but those are at very, very small distances, |

tedtalks |
00:42 00:45 |
and we haven't really interacted with them very much yet. |

tedtalks |
00:45 00:49 |
The main thing I want to talk about is this: |

tedtalks |
00:49 00:53 |
that we have this remarkable experience in this field of fundamental physics |

tedtalks |
00:53 01:00 |
that beauty is a very successful criterion for choosing the right theory. |

tedtalks |
01:00 01:05 |
And why on earth could that be so? |

tedtalks |
01:05 01:08 |
Well, here's an example from my own experience. |

tedtalks |
01:08 01:13 |
It's fairly dramatic, actually, to have this happen. |

tedtalks |
01:13 01:16 |
Three or four of us, in 1957, |

tedtalks |
01:16 01:21 |
put forward a partially complete theory of one of these forces, this weak force. |

tedtalks |
01:21 01:27 |
And it was in disagreement with seven -- seven, count them, seven experiments. |

tedtalks |
01:27 01:30 |
Experiments were all wrong. |

tedtalks |
01:30 01:32 |
And we published before knowing that, |

tedtalks |
01:32 01:35 |
because we figured it was so beautiful, it's gotta be right! |

tedtalks |
01:35 01:38 |
The experiments had to be wrong, and they were. |

tedtalks |
01:38 01:41 |
Now our friend over there, Albert Einstein, |

tedtalks |
01:41 01:45 |
used to pay very little attention when people said, |

tedtalks |
01:45 01:50 |
"You know, there's a man with an experiment that seems to disagree with special relativity. |

tedtalks |
01:50 01:59 |
DC Miller. What about that?" And he would say, "Aw, that'll go away." (Laughter) |

tedtalks |
01:59 02:02 |
Now, why does stuff like that work? That's the question. |

tedtalks |
02:02 02:07 |
Now, yeah, what do we mean by beautiful? That's one thing. |

tedtalks |
02:07 02:10 |
I'll try to make that clear -- partially clear. |

tedtalks |
02:10 02:15 |
Why should it work, and is this something to do with human beings? |

tedtalks |
02:15 02:18 |
I'll let you in on the answer to the last one that I offer, |

tedtalks |
02:18 02:20 |
and that is, it has nothing to do with human beings. |

tedtalks |
02:20 02:25 |
Somewhere in some other planet, orbiting some very distant star, |

tedtalks |
02:25 02:27 |
maybe in a another galaxy, |

tedtalks |
02:27 02:31 |
there could well be entities that are at least as intelligent as we are, |

tedtalks |
02:31 02:36 |
and are interested in science. It's not impossible; I think there probably are lots. |

tedtalks |
02:36 02:39 |
Very likely, none is close enough to interact with us. |

tedtalks |
02:39 02:44 |
But they could be out there, very easily. |

tedtalks |
02:44 02:50 |
And suppose they have, you know, very different sensory apparatus, and so on. |

tedtalks |
02:50 02:55 |
They have seven tentacles, and they have 14 little funny-looking compound eyes, |

tedtalks |
02:55 02:59 |
and a brain shaped like a pretzel. |

tedtalks |
02:59 03:02 |
Would they really have different laws? |

tedtalks |
03:02 03:06 |
There are lots of people who believe that, and I think it is utter baloney. |

tedtalks |
03:06 03:08 |
I think there are laws out there, |

tedtalks |
03:08 03:14 |
and we of course don't understand them at any given time very well |

tedtalks |
03:14 03:17 |
-- but we try. And we try to get closer and closer. |

tedtalks |
03:17 03:21 |
And someday, we may actually figure out the fundamental unified theory |

tedtalks |
03:21 03:26 |
of the particles and forces, what I call the "fundamental law." |

tedtalks |
03:26 03:28 |
We may not even be terribly far from it. |

tedtalks |
03:28 03:31 |
But even if we don't run across it in our lifetimes, |

tedtalks |
03:31 03:34 |
we can still think there is one out there, |

tedtalks |
03:34 03:36 |
and we're just trying to get closer and closer to it. |

tedtalks |
03:36 03:39 |
I think that's the main point to be made. |

tedtalks |
03:39 03:42 |
We express these things mathematically. |

tedtalks |
03:42 03:44 |
And when the mathematics is very simple -- |

tedtalks |
03:44 03:48 |
when in terms of some mathematical notation, |

tedtalks |
03:48 03:54 |
you can write the theory in a very brief space, without a lot of complication -- |

tedtalks |
03:54 03:58 |
that's essentially what we mean by beauty or elegance. |

tedtalks |
03:58 04:04 |
Here's what I was saying about the laws. They're really there. |

tedtalks |
04:04 04:06 |
Newton certainly believed that. |

tedtalks |
04:06 04:16 |
And he said, here, "It is the business of natural philosophy to find out those laws." |

tedtalks |
04:16 04:19 |
The basic law, let's say -- here's an assumption. |

tedtalks |
04:19 04:22 |
The assumption is that the basic law really takes the form |

tedtalks |
04:22 04:25 |
of a unified theory of all the particles. |

tedtalks |
04:25 04:28 |
Now, some people call that a theory of everything. |

tedtalks |
04:28 04:33 |
That's wrong because the theory is quantum mechanical. |

tedtalks |
04:33 04:37 |
And I won't go into a lot of stuff about quantum mechanics and what it's like, and so on. |

tedtalks |
04:37 04:42 |
You've heard a lot of wrong things about it anyway. (Laughter) |

tedtalks |
04:42 04:45 |
There are even movies about it with a lot of wrong stuff. |

tedtalks |
04:45 04:50 |
But the main thing here is that it predicts probabilities. |

tedtalks |
04:50 04:53 |
Now, sometimes those probabilities are near certainties. |

tedtalks |
04:53 04:56 |
And in a lot of familiar cases, they of course are. |

tedtalks |
04:56 05:02 |
But other times they're not, and you have only probabilities for different outcomes. |

tedtalks |
05:02 05:08 |
So what that means is that the history of the universe is not determined just by the fundamental law. |

tedtalks |
05:08 05:13 |
It's the fundamental law and this incredibly long series of accidents, |

tedtalks |
05:13 05:18 |
or chance outcomes, that are there in addition. |

tedtalks |
05:18 05:24 |
And the fundamental theory doesn't include those chance outcomes; they are in addition. |

tedtalks |
05:24 05:28 |
So it's not a theory of everything. And in fact, a huge amount of the information |

tedtalks |
05:28 05:32 |
in the universe around us comes from those accidents, |

tedtalks |
05:32 05:35 |
and not just from the fundamental laws. |

tedtalks |
05:35 05:43 |
Now, it's often said that getting closer and closer |

tedtalks |
05:43 05:48 |
to the fundamental laws by examining phenomena at low energies, and then higher energies, |

tedtalks |
05:48 05:51 |
and then higher energies, or short distances, and then shorter distances, |

tedtalks |
05:51 05:55 |
and then still shorter distances, and so on, is like peeling the skin of an onion. |

tedtalks |
05:55 05:57 |
And we keep doing that, |

tedtalks |
05:57 06:01 |
and build more powerful machines, accelerators for particles. |

tedtalks |
06:01 06:06 |
We look deeper and deeper into the structure of particles, |

tedtalks |
06:06 06:13 |
and in that way we get probably closer and closer to this fundamental law. |

tedtalks |
06:13 06:19 |
Now, what happens is that as we do that, as we peel these skins of the onion, |

tedtalks |
06:19 06:22 |
and we get closer and closer to the underlying law, |

tedtalks |
06:22 06:27 |
we see that each skin has something in common with the previous one, |

tedtalks |
06:27 06:31 |
and with the next one. We write them out mathematically, |

tedtalks |
06:31 06:34 |
and we see they use very similar mathematics. |

tedtalks |
06:34 06:37 |
They require very similar mathematics. |

tedtalks |
06:37 06:41 |
That is absolutely remarkable, and that is a central feature |

tedtalks |
06:41 06:46 |
of what I'm trying to say today. |

tedtalks |
06:46 06:49 |
Newton called it -- that's Newton, by the way -- that one. |

tedtalks |
06:49 06:56 |
This one is Albert Einstein. Hi, Al! And anyway, |

tedtalks |
06:56 07:03 |
he said, "nature conformable to herself" -- personifying nature as a female. |

tedtalks |
07:03 07:08 |
And so what happens is that the new phenomena, |

tedtalks |
07:08 07:14 |
the new skins, the inner skins of the slightly smaller skins of the onion |

tedtalks |
07:14 07:18 |
that we get to, resemble the slightly larger ones. |

tedtalks |
07:18 07:24 |
And the kind of mathematics that we had for the previous skin |

tedtalks |
07:24 07:28 |
is almost the same as what we need for the next skin. |

tedtalks |
07:28 07:32 |
And that's why the equations look so simple. |

tedtalks |
07:32 07:35 |
Because they use mathematics we already have. |

tedtalks |
07:35 07:40 |
A trivial example is this: Newton found the law of gravity, |

tedtalks |
07:40 07:45 |
which goes like one over the square of the distance between the things gravitated. |

tedtalks |
07:45 07:50 |
Coulomb, in France, found the same law for electric charges. |

tedtalks |
07:50 07:52 |
Here's an example of this similarity. |

tedtalks |
07:52 07:55 |
You look at gravity, you see a certain law. |

tedtalks |
07:55 07:58 |
Then you look at electricity. Sure enough. The same rule. |

tedtalks |
07:58 08:00 |
It's a very simple example. |

tedtalks |
08:00 08:04 |
There are lots of more sophisticated examples. |

tedtalks |
08:04 08:06 |
Symmetry is very important in this discussion. |

tedtalks |
08:06 08:09 |
You know what it means. A circle, for example, |

tedtalks |
08:09 08:13 |
is symmetric under rotations about the center of the circle. |

tedtalks |
08:13 08:18 |
You rotate around the center of the circle, the circle remains unchanged. |

tedtalks |
08:18 08:21 |
You take a sphere, in three dimensions, you rotate around the center of the sphere, |

tedtalks |
08:21 08:25 |
and all those rotations leave the sphere alone. |

tedtalks |
08:25 08:26 |
They are symmetries of the sphere. |

tedtalks |
08:26 08:30 |
So we say, in general, that there's a symmetry |

tedtalks |
08:30 08:34 |
under certain operations if those operations leave the phenomenon, |

tedtalks |
08:34 08:37 |
or its description, unchanged. |

tedtalks |
08:37 08:40 |
Maxwell's equations are of course symmetrical |

tedtalks |
08:40 08:42 |
under rotations of all of space. |

tedtalks |
08:42 08:46 |
Doesn't matter if we turn the whole of space around by some angle, |

tedtalks |
08:46 08:50 |
it doesn't leave the -- doesn't change the phenomenon of electricity or magnetism. |

tedtalks |
08:50 08:54 |
There's a new notation in the 19th century that expressed this, |

tedtalks |
08:54 08:58 |
and if you use that notation, the equations get a lot simpler. |

tedtalks |
08:58 09:01 |
Then Einstein, with his special theory of relativity, |

tedtalks |
09:01 09:04 |
looked at a whole set of symmetries of Maxwell's equations, |

tedtalks |
09:04 09:07 |
which are called special relativity. |

tedtalks |
09:07 09:12 |
And those symmetries, then, make the equations even shorter, and even prettier, therefore. |

tedtalks |
09:12 09:15 |
Let's look. You don't have to know what these things mean, doesn't make any difference. |

tedtalks |
09:15 09:19 |
But you can just look at the form. (Laughter) You can look at the form. |

tedtalks |
09:19 09:21 |
You see above, at the top, a long list |

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09:21 09:27 |
of equations with three components for the three directions of space: x, y and z. |

tedtalks |
09:27 09:33 |
Then, using vector analysis, you use rotational symmetry, and you get this next set. |

tedtalks |
09:33 09:37 |
Then you use the symmetry of special relativity and you get an even simpler set |

tedtalks |
09:37 09:41 |
down here, showing that symmetry exhibits better and better. |

tedtalks |
09:41 09:47 |
The more and more symmetry you have, the better you exhibit the simplicity and elegance of the theory. |

tedtalks |
09:47 09:51 |
The last two, the first equation says that electric charges and currents |

tedtalks |
09:51 09:55 |
give rise to all the electric and magnetic fields. |

tedtalks |
09:55 10:00 |
The next -- second -- equation says that there is no magnetism other than that. |

tedtalks |
10:00 10:03 |
The only magnetism comes from electric charges and currents. |

tedtalks |
10:03 10:08 |
Someday we may find some slight hole in that argument. |

tedtalks |
10:08 10:12 |
But for the moment, that's the case. |

tedtalks |
10:12 10:16 |
Now, here is a very exciting development that many people have not heard of. |

tedtalks |
10:16 10:21 |
They should have heard of it, but it's a little tricky to explain in technical detail, |

tedtalks |
10:21 10:24 |
so I won't do it. I'll just mention it. (Laughter) |

tedtalks |
10:24 10:34 |
But Chen Ning Yang, called by us "Frank" Yang -- (Laughter) |

tedtalks |
10:34 10:38 |
-- and Bob Mills put forward, 50 years ago, |

tedtalks |
10:38 10:42 |
this generalization of Maxwell's equations, with a new symmetry. |

tedtalks |
10:42 10:44 |
A whole new symmetry. |

tedtalks |
10:44 10:47 |
Mathematics very similar, but there was a whole new symmetry. |

tedtalks |
10:47 10:52 |
They hoped that this would contribute somehow to particle physics |

tedtalks |
10:52 10:56 |
-- didn't. It didn't, by itself, contribute to particle physics. |

tedtalks |
10:56 11:01 |
But then some of us generalized it further. And then it did! |

tedtalks |
11:01 11:06 |
And it gave a very beautiful description of the strong force and of the weak force. |

tedtalks |
11:06 11:09 |
So here we say, again, what we said before: |

tedtalks |
11:09 11:13 |
that each skin of the onion shows a similarity to the adjoining skins. |

tedtalks |
11:13 11:18 |
So the mathematics for the adjoining skins is very similar to what we need for the new one. |

tedtalks |
11:18 11:20 |
And therefore it looks beautiful |

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11:20 11:24 |
because we already know how to write it in a lovely, concise way. |

tedtalks |
11:24 11:33 |
So here are the themes. We believe there is a unified theory underlying all the regularities. |

tedtalks |
11:33 11:37 |
Steps toward unification exhibit the simplicity. |

tedtalks |
11:37 11:39 |
Symmetry exhibits the simplicity. |

tedtalks |
11:39 11:43 |
And then there is self-similarity across the scales -- in other words, |

tedtalks |
11:43 11:45 |
from one skin of the onion to another one. |

tedtalks |
11:45 11:50 |
Proximate self-similarity. And that accounts for this phenomenon. |

tedtalks |
11:50 11:57 |
That will account for why beauty is a successful criterion for selecting the right theory. |

tedtalks |
11:57 11:58 |
Here's what Newton himself said: |

tedtalks |
11:58 12:02 |
"Nature is very consonant and conformable to her self." |

tedtalks |
12:02 12:06 |
One thing he was thinking of is something that most of us take for granted today, |

tedtalks |
12:06 12:09 |
but in his day it wasn't taken for granted. |

tedtalks |
12:09 12:15 |
There's the story, which is not absolutely certain to be right, but a lot of people told it. |

tedtalks |
12:15 12:19 |
Four sources told it. That when they had the plague in Cambridge, |

tedtalks |
12:19 12:23 |
and he went down to his mother's farm -- because the university was closed -- |

tedtalks |
12:23 12:27 |
he saw an apple fall from a tree, or on his head or something. |

tedtalks |
12:27 12:31 |
And he realized suddenly that the force that drew the apple down to the earth |

tedtalks |
12:31 12:37 |
could be the same as the force regulating the motions of the planets and the moon. |

tedtalks |
12:37 12:42 |
That was a big unification for those days, although today we take it for granted. |

tedtalks |
12:42 12:46 |
It's the same theory of gravity. |

tedtalks |
12:46 12:51 |
So he said that this principle of nature, consonance: |

tedtalks |
12:51 12:56 |
"This principle of nature being very remote from the conceptions of philosophers, |

tedtalks |
12:56 12:59 |
I forbore to describe it in that book, |

tedtalks |
12:59 13:03 |
lest I should be accounted an extravagant freak ... " |

tedtalks |
13:03 13:08 |
That's what we all have to watch out for, (Laughter) especially at this meeting. |

tedtalks |
13:08 13:13 |
" ... and so prejudice my readers against all those things which were the main design of the book." |

tedtalks |
13:13 13:17 |
Now, who today would claim that as a mere conceit of the human mind? |

tedtalks |
13:17 13:21 |
That the force that causes the apple to fall to the ground |

tedtalks |
13:21 13:24 |
is the same force that causes the planets and the moon to move around, |

tedtalks |
13:24 13:29 |
and so on? Everybody knows that. It's a property of gravitation. |

tedtalks |
13:29 13:33 |
It's not something in the human mind. The human mind can, of course, appreciate it |

tedtalks |
13:33 13:38 |
and enjoy it, use it, but it's not -- it doesn't stem from the human mind. |

tedtalks |
13:38 13:40 |
It stems from the character of gravity. |

tedtalks |
13:40 13:42 |
And that's true of all the things we're talking about. |

tedtalks |
13:42 13:44 |
They are properties of the fundamental law. |

tedtalks |
13:44 13:50 |
The fundamental law is such that the different skins of the onion resemble one another, |

tedtalks |
13:50 13:54 |
and therefore the math for one skin allows you to express beautifully and simply |

tedtalks |
13:54 13:57 |
the phenomenon of the next skin. |

tedtalks |
13:57 14:00 |
I say here that Newton did a lot of things that year: |

tedtalks |
14:00 14:06 |
gravity, the laws of motion, the calculus, white light composed of all the colors of the rainbow. |

tedtalks |
14:06 14:12 |
And he could have written quite an essay on "What I Did Over My Summer Vacation." |

tedtalks |
14:12 14:16 |
(Laughter) |

tedtalks |
14:16 14:26 |
So we don't have to assume these principles as separate metaphysical postulates. |

tedtalks |
14:26 14:32 |
They follow from the fundamental theory. |

tedtalks |
14:32 14:34 |
They are what we call emergent properties. |

tedtalks |
14:34 14:41 |
You don't need -- you don't need something more to get something more. |

tedtalks |
14:41 14:43 |
That's what emergence means. |

tedtalks |
14:43 14:52 |
Life can emerge from physics and chemistry, plus a lot of accidents. |

tedtalks |
14:52 14:57 |
The human mind can arise from neurobiology and a lot of accidents, |

tedtalks |
14:57 15:04 |
the way the chemical bond arises from physics and certain accidents. |

tedtalks |
15:04 15:08 |
It doesn't diminish the importance of these subjects |

tedtalks |
15:08 15:14 |
to know that they follow from more fundamental things, plus accidents. |

tedtalks |
15:14 15:19 |
That's a general rule, and it's critically important to realize that. |

tedtalks |
15:19 15:23 |
You don't need something more in order to get something more. |

tedtalks |
15:23 15:27 |
People keep asking that when they read my book, "The Quark and the Jaguar," |

tedtalks |
15:27 15:31 |
and they say, "Isn't there something more beyond what you have there?" |

tedtalks |
15:31 15:35 |
Presumably, they mean something supernatural. |

tedtalks |
15:35 15:37 |
Anyway, there isn't. (Laughter) |

tedtalks |
15:37 15:42 |
You don't need something more to explain something more. |

tedtalks |
15:42 15:45 |
Thank you very much. (Applause) |