[open-science] Fwd: [tt] A conversation with Freeman Dyson

[Bryan Bishop]

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From: Eugen Leitl <eugen at leitl.org>
Date: Thu, Jun 25, 2009 at 7:55 AM
Subject: [tt] A conversation with Freeman Dyson
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http://plus.maths.org/issue26/features/dyson/index.html

A conversation with Freeman Dyson

by Helen Joyce

Freeman Dyson has had a long and distinguished career in physics. The holder
of a Professorship at the Princeton Institute for Advanced Study for more
than 40 years, he did fundamental work on internal physics of stars and the
interactions of subatomic particle beams. He is the author of several popular
science books, advocates space colonisation and the search for
extraterrestrial life, and is a passionate speaker on topics as wideranging
as GM crops and the search for world peace.

He describes the way he does physics as "a sort of architecture done with
equations, rather than with bits of wood and steel". A self-confessed
optimist, he says that having unsolved problems is what makes life
interesting.

In the summer of 2003, Dyson gave the annual Dirac lecture at the University
of Cambridge, entitled Looking for Life in Unlikely Places. Afterwards, Plus
spoke to him about his life in science.

You can watch, or just listen to, the interview and lecture at
http://www.xscite.com/FreemanDyson.

Freeman Dyson

Freeman Dyson in the grounds of St. Johns College after delivering the Dirac
Lecture, June 2003.  Photo and copyright Anna N. Zytkow

Why do you find maths fascinating?

I've never remembered a time when I wasn't in love with calculating. One of
the first memories I have was when I was still being put down for a nap in
the afternoons. I was in the crib and not able to climb out, and I was
calculating the infinite series, 1+1/2+1/4+1/8+1/16... and discovered that it
came out to 2. I remember that very vividly. It was a big moment when I found
that out. I just loved calculating. It's something you're born with - it
certainly didn't come from outside as far as I know.

The kind of math that I've done all my life is old-fashioned math. I never
became a modern mathematician, never learned any of the abstract stuff. What
I do is really nineteenth century, and it turns out of course that that is
what you need for applied math. The nineteenth century is a good place to
start if you want to be useful!

Is it possible, or desirable, to do physics without maths?

Yes. Dick Feynman, who was my mentor as a physicist, had very little math. He
never really thought in terms of mathematics; he had a very concrete
imagination. He drew pictures instead of making calculations, and somehow got
the right answers.

But of course he was really a unique character, not only in his work but also
in his personality. He had this remarkable vision of things, he called it the
space-time approach. It meant he could reconstruct the whole of physics from
his own point of view, without much in the way of equations. Instead of
writing down an equation and solving it he would just write down the answer,
which other people can't do. It was combined with some sort of geometrical
pictures he had in his head. There have been others like that - he's not the
only one - but it is unusual.

I work completely from a mathematical point of view, I was just the opposite.
I have to have an equation that I can solve. So I do it the old-fashioned
way, and then of course the fun was to understand what he was doing from my
point of view, which turned out to be very interesting - I was able to
translate his style into old-fashioned mathematics so other people could use
it.

What has your mathematical training brought to what you have done?

My main teacher as a mathematician was a wonderful gentleman called
Besicovitch who lived here in Cambridge. He was an emigre Russian, he talked
with a very thick Russian accent - he was a great character. My style as a
mathematician was strongly influenced by Besicovitch.

He worked on the borderline between geometry and set theory, both of which
are kind of nineteenth century. He did beautiful proofs which are kind of
architectural. Besicovitch's style was to take some rather simple question
and build up an enormously elaborate construction to show that such a thing
worked or didn't work and then get a very simple answer at the end. And
that's typical of the way I do physics. It's a sort of architecture done with
equations, rather than with bits of wood and steel.

Freeman Dyson and Martin Rees

Freeman Dyson with Martin Rees (centre) and Douglas Gough in the grounds of
St Johns College, Cambridge, June 2003.  Photo and copyright Anna N. Zytkow

In your popular books you comment on topics that are not directly related to
your work as a physicist. So you obviously feel that mathematicians and
scients have a wide role to play in society as commentators or guides. What
motivates you in this wider search for meaning and truth?

I suppose the fact that my interests have always been very much broader than
my skills! My skills have always been just playing around with equations, but
there is much more to life than equations. I've been interested in big human
problems, and growing up through World War II I had an acute experience of
war. I was involved with the bombing campaign in World War II, so it gave me
the feeling that war and peace was something we have to deal with. So that's
always been a big driving force for me, coming to grips with the problems of
war and peace.

Freeman Dyson and Mike Green

Freeman Dyson with Mike Green, Martin Rees and John Barrow in the background,
in the grounds of St Johns College, Cambridge, June 2003.  Photo and
copyright Anna N. Zytkow

I think the reason why scientists can deal with that is because we have an
additional qualification which is nothing to do with the technical parts of
science, which is that we are operating in an international community.
Science is about the most international activity there is. We have friends
and colleagues all over the world, including countries that are not supposed
to be respectable. It's a great tradition in science that you talk to
everybody and that you all understand the same things and you all understand
them in more or less the same way. So as scientists we're setting a model for
the world - how to operate a global enterprise without coming into collision.
I think that's something we can do much better than the politicians.

I worked for a while in the United States in the Disarmament Agency which was
the part of Government concerned with arms control. That was during the
Kennedy administration, so it was forty years ago. The Disarmament Agency was
just new then. It was only about 100 people in the whole administration. Ten
of us were scientists, and the other ninety were mostly ex-ambassadors and
diplomatic types and the ten scientists were doing all of the work, not
because we were experts on bombs, but because we were accustomed to talking
with the Russians and the Chinese and the other people who were supposed to
be bad guys, and the diplomats weren't. We really believed in coming to
agreements much more than the diplomats did.

I suppose that could be true of all academics - do you think it is more true
of scientists?

Well, I wouldn't say that dogmatically, but I do think it is true. Science
does translate much better than, say, history or law or literature. We can
read other people's literature, but that is for most people an effort; most
people rely on translations, so it's very different. In science you don't
need translations.

Do you feel that modern scientists have an ethical role to play in the world?

Very definitely. Of course we don't all agree about ethics, but still the
ethics of science I think is extremely important to most of us. First of all,
not claiming to know more than you know. That's the most important thing,
that science is about uncertainty rather than about certainty. So it's very
different from law where everything has to be in black and white, and it's
different from religion too. This tradition of admitting when you're wrong is
very important. In science when you're proved wrong you just goodhumouredly
say 'well, yes, I was wrong', which other people find not so easy.

You describe yourself as an optimist - why is this?

The reason I'm optimistic is easy to see; it's because I came through the
1930s. I was a teenager in the 1930s, when things were from every point of
view much worse than they ate, it's an opportunity for doing better.

Freeman Dyson with the statue of Fred Hoyle

Freeman Dyson with the statue of Fred Hoyle in the grounds of the Institute
of Astronomy, Cambridge, June 2003.  Photo and copyright Anna N. Zytkow

So there are many reasons, but I think having lived through bad times is the
main reason. World War II was bad enough, but it was nothing like as bad as
we expected. We had read Aldous Huxley's Brave New World and he starts out
with anthrax bombs - well, we expected anthrax bombs, there's nothing new
about anthrax. It never happened, so we were lucky.

In all sorts of ways we were lucky; of course England had a better war than
many places. But still, it was a tough war and nevertheless we survived, so,
having lived through that, I can't take the present problems so seriously. I
think none of the present-day problems are as bad as what we faced then.

And you see science and technology as being part of the solution?

It has been, yes, especially if you go to China and countries in Africa. They
have a very different view of science because they know they absolutely need
it. You can't imagine China in its present state of economic growth without
modern technology, and of course China has got enormously more prosperous
just in the last ten years. They have a very positive attitude toward
technology, including genetic engineering.

The same is true of the people I know in Africa. For them, science really is
a necessity of life. They don't have such mixed feelings about it.

Do we have a job to do as scientists here in the rich world, to persuade
people that the doomsaying isn't necessarily correct?

Yes - but I don't try to impose my views on everybody. It's quite good to
have some people to go around preaching gloom and doom, but I don't happen to
agree with them. And I think it's unfair if we try to impose those views on
the Chinese and the Africans.

What have you found fun about being a scientist?

The thing I have found most delightful is having friends all over the world.
I just spent a couple of weeks in China. You are greeted there as a friend
and colleague, and immediately you talk the same language, even if it is not
Chinese! I don't have a word of Chinese, but still we could communicate
pretty well.

Without the science I would just be a tourist and it does make a huge
difference, having a professional contact. Of course, there are other
professions which have the same kind of international spread - if you're a
musician it's the same - but not for most.

And what about the actual doing of science?

That of course is always fun, because, especially being a theorist, I am free
to jump around. I don't have to deal with apparatus, so if I get bored with a
problem I can just scrap it and start on something else, which is what I
frequently do. So I have great freedom, and especially in astronomy, we're
never running out of problems.

At the moment, the two most vigorously active branches of science are
astronomy and biology, and in both of them there is no shortage of
interesting things to do, and not likely to be for the next hundred years.

There is a theorem proved by Kurt Godel in 1931, which is the Incompleteness
Theorem for mathematics. The theorem says that if you have any finite
formulation of mathematics, that is, a finite set of equations and a finite
set of rules of logical inference, then you can write down statements within
the language that is defined that way, and you can prove that they cannot be
proved and that they cannot be disproved.

So given any finite system of mathematics, there are statements within the
system that you can't decide whether they are true or untrue by using the
rules, which is a very powerful and profound result. It means that any
formulation of mathematics is incomplete; there are always questions that you
can't answer within the system.

In fact it means that mathematics is inexhaustible - given any particular set
of rules there are questions that you can't answer. You always have to invent
new rules in order to decide new questions. So it's guaran end of problems
either.

I think you finding that consoling is probably the definition of being an
optimist!

The point is that having unsolved problems is what makes life interesting. To
me the idea of solving all the problems in science or in anything else is the
most gloomy prospect I can imagine.

About this article

Professor Freeman Dyson is now retired from his Professorship in Physics at
the Institute for Advanced Study in Princeton, where he spent most of his
working life. On 16th June, 2003, he gave the annual Dirac Lecture at the
Centre for Mathematical Sciences in Cambridge. His talk, entitled "Looking
for life in unlikely places: reasons why planets may not be the best places
to look for life", was recorded and edited by Bjorn Hassler and Adrian
Cullum-Hanshaw of the Department of Applied Mathematics and Theoretical
Physics at Cambridge.

You can watch, or just listen to, this interview and the Dirac Lecture at
http://www.xscite.com/FreemanDyson.

Dr. Anna N. Zytkow of the Institute of Astronomy in Cambridge very kindly
allowed Plus to use photographs she took during Professor Dyson's visit to
Cambridge in June 2003.
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