Monday, 24 March 2008

Richard Feynman: part 3

In part 2, I picked up themes from the first two chapters of Richard Feynman's The Character of Physical Law. In this part, I want to look at a particular theme that occurs in the remaining chapters of that book. It is already there in what I said in part 2, but it is something that gains emphasis later in the book. It is a theme of unity in our knowledge of the world.


Chapter 3 looks at what Feynman calls "The great Conservation Principles". He looks at conservation of quantities like charge, energy, momentum and angular momentum. Feynman observes that, as far as we can tell today, what he terms the "great" conservation laws are absolutely accurate. Some others are only approximate, but are still useful. In concluding this chapter, Feynman writes (emphasis is mine):



"Discovering the laws of physics is like trying to put together the pieces of a jigsaw puzzle. We have all these different pieces, and today they are proliferating rapidly. Many of them are lying about and cannot be fitted with the other ones. How do we know that they belong together? How do we know that they are really all part of one as yet incomplete picture? We are not sure, and it worries us to some extent, but we get encouragement from the common characteristics of several pieces. They all show blue sky, or they are all made out of the same kind of wood. All the various physical laws obey the same conservation principles."



Towards the end of a chapter on the distinction between past and future, Feynman writes as follows:

".. an understanding of physical laws does not necessarily give you an understanding of things of significance in the world in any direct way. The details of real experience are often very far from the fundamental laws. We have a way of discussing the world, when we talk of it at various hierarchies or levels... For example, we have at one end fundamental laws of physics. Then we invent terms for concepts which are approximate, which have, we believe, their ultimate explanation in terms of the fundamental laws. For instance, 'heat'."

Feynman outlines an ascent up a continuing "hierarchy of complexity" to the features of living beings (again, emphasis is mine).

"And then we go on, and we come to words and concepts like 'man', and 'history', or 'political expediency', and so forth, a series of concepts that we use to understand things at an ever higher level. And going on, we come to things like evil, and beauty, and hope ...

"Which end is nearer to God; if I may use a religious metaphor. Beauty and hope, or the fundamental laws? I think that the right way, of course, is to say that what we have to look at is the whole structural interconnection of the thing; and that all the sciences, and not just the sciences, but all the efforts of intellectual kinds, are an endeavour to see the connections of the hierarchies, to connect beauty to history, to connect history to man's psychology, man's psychology to the working of the brain, the brain to the neural impulse, the neural impulse to the chemistry, and so forth, up and down, both ways...

"And I do not think either end is nearer to God... And to stand with evil and beauty and hope, or to stand with the fundamental laws, hoping that way to get a deep understanding of the whole world, with that aspect alone, is a mistake. It is not sensible for the ones who specialise at one end, and the ones who specialise at the other end, to have such a disregard for each other. (They don't actually, but people say they do). The great mass of workers in between, connecting one step to another, are improving all the time our understanding of the world ... and in that way we are gradually understanding this tremendous world of interconnecting hierarchies."

Leaving aside for the moment the references to God, and what these references tell us about Richard Feynman's views on religion, there is here a clear affirmation that the physical sciences alone are not able to tell us everything about the world. At the very least, the human sciences must also be engaged. The reference to such ideas as evil, beauty and hope suggests that philosophy must be involved in our search to understand the world - as well as physics.

In this context, the last two paragraphs of the whole book are interesting (emphases are again mine):

"In this age people are experiencing a delight, the tremendous delight that you get when you guess how nature will work in a new situation never seen before. From experiments and information in a certain range you can guess what is going to happen in a region where no one has ever explored before...

"What is it about nature that lets this happen, that it is possible to guess from one part what the rest is going to do? This is an unscientific question: I do not know how to answer it, and therefore I am going to give an unscientific answer. I think it is because nature has a simplicity and therefore a great beauty."

I want to suggest that, in saying that the question is "unscientific" and in giving an "unscientific answer", Feynman is recognising that the question takes him from one level in the hierarchy of connections to another. The question is a philosophical one, not one about the physical laws themselves. It therefore deserves a philosophical answer, that is, an "unscientific answer", and not an answer determined from the physical laws themselves. The descriptor "unscientific" does not imply any illegitimacy in either the question or the answer. Or at least this is what I would like to think Feynman meant to say, though I must admit to not being absolutely sure that it is what he meant.

The reference to "simplicity" and "great beauty" can be clearly related to the suggestions of a unity in the physical world indicated above.

6 comments:

veniteadoremus said...

"And to stand with evil and beauty and hope, or to stand with the fundamental laws, hoping that way to get a deep understanding of the whole world, with that aspect alone, is a mistake."

I'm very happy to have read that. I have an atheistic friend who still has to learn that - his religion is science, and I'm afraid he will suffer some disillusions as he continues in the scientific world...

On the other side, the beauty of some parts of physics has been very important to my view of Creation and through that, its Creator. I wish I could share that experience with more of my religious friends. Feynman's statement works both ways.

Mike Gottlieb said...

Richard P. Feynman was an atheist, pure and simple; this is well-documented in biographies, interviews, letters, etc. (Notice in the above quotation that Feynman refers to god as "a religious metaphor.") It is equally well-documented that Feynman had an extremely low opinion of philosophers, psychologists and other so-called "social scientists." Therefore, in my opinion, Joe is extrapolating too much from this isolated passage. Feynman was certainly not a supporter of human sciences or philosophy (as commonly practiced). Furthermore, Feynman has stated clearly and unambiguously (elsewhere) that in his opinion there may or may not be unity in (the laws of) nature - it is not required. Nature simply is what it is, and the job of the scientist is to discover what that is with an open mind, not imposing any preconceived notions such as "unity." Thus the references to "simplicity" and "great beauty" in the above-quoted lecture do not suggest, to me, that Feynman ever believed in an overall "unity" in the physical world. And (in response to the first comment) Feynman certainly would have strongly opposed the idea that nature is a "Creation" of a "Creator," so to claim that Feynman's statements support such an idea in any way, shape or form is absurd.

Joe said...

Dear Mike

Thank you once again for taking the trouble to comment. I think that what you have pointed out about Richard Feynman's atheism, and about his not supporting the imposition of preconceived notions on the world studied by physics, is important.

What I would want to suggest is that, when he looks at nature and takes it as it is, something that I think Feynman does with great integrity, he sees a unity that is there. This is the same sense in which, in my part 2 post, I compared Feynman's presentation in chapters 1 and 2 of The Character of Physical Law to the philosophical presentation of S L Jaki. What Jaki presents as "philosophy" (and Feynman would therefore view as unwarranted preconception) I believe Feynman sees in nature, purely with the eyes of physics, as he lets nature speak for itself.

What I have still to understand in my own mind is why Richard seems to go to the very edge of what a philosopher would term metaphysics, and then holds back.

I am not sure that my first commenter intended to say that Feynman believed in a Creator and in nature as Creation - but the suggestion of beauty in nature, to which Feynman bears witness purely as physicist, is something that can speak of other beauty to the person who is able to make that step from phsyics to metaphysics. I believe that it is legitimate to quote Feynman in this way, as a witness to nature, though, to be accurate to Feynman. we have to recognise that he would not "follow through" in the same way.

Thank you again for your comment.

Michael A. Gottlieb said...

Dear Joe,

I apologize for being so tardy with this comment on your comment (to my comment).

Something you wrote did not ring true to me: your statement that "when [Feynman] looks at nature and takes it as it is, something that I think Feynman does with great integrity, he sees a unity _that is there_." I think this needs to be modified somewhat because, so far as I know, there is no such unity in nature, as seen by the physicist at least, and Feynman states this in several places in The Feynman Lectures on Physics.

For example, when he discusses symmetries and conservation laws in chapter 52 of Volume I, he is also quick to point out how some of the apparent symmetries, when examined closely, are imperfect, or "broken." He writes:

"The marvelous thing about it all is that for such a wide range of important, strong phenomena--nuclear forces, electrical phenomena, and even weak ones like gravitation--over a tremendous range of physics, all the laws for these seem to be symmetrical. On the other hand, this little extra piece says, "No, the laws are not symmetrical!" How is it that nature can be almost symmetrical, but not perfectly symmetrical? What shall we make of this?
---
We have, in our minds, a tendency to accept symmetry as some kind of perfection. In fact it is like the old idea of the Greeks that circles were perfect, and it was rather horrible to believe that the planetary orbits were not circles, but only nearly circles. The difference between being a circle and being nearly a circle is not a small difference, it is a fundamental change so far as the mind is concerned."

Here we see that the unity in nature seemingly implied by symmetries (or their corresponding conservation laws) does not hold up very well under careful scrutiny. Perhaps a clearer example of Feynman's point of view regarding unity (or the lack thereof) in nature (as seen by the physicist) comes from chapter 2 of Volume I where he writes:

"The question is, of course, is it going to be possible to amalgamate everything, and merely discover that this world represents different aspects of one thing? Nobody knows. All we know is that as we go along, we find that we can amalgamate pieces, and then we find some pieces that do not fit, and we keep trying to put the jigsaw puzzle together. Whether there are a finite number of pieces, and whether there is even a border to the puzzle, is of course unknown. It will never be known until we finish the picture, if ever."

In chapter 25 of Volume II Feynman pokes fun at misguided attempts to "unify" physical laws:

"Let us show you something interesting that we have recently discovered: All of the laws of physics can be contained in one equation. That equation is

U = 0

What a simple equation! Of course, it is necessary to know what the symbol means. U is a physical quantity which we will call the "unworldliness" of the situation. And we have a formula for it. Here is how you calculate the unworldliness. You take all of the known physical laws and write them in a special form. For example, suppose you take the law of mechanics, F = ma, and rewrite it as F - ma = 0. Then you can call (F - ma) -- which should, of course, be zero -- the "mismatch" of mechanics. Next, you take the square of this mismatch and call it U1, which can be called the "unworldliness of mechanical effects." In other words, you take

U1 = (F - ma)^2

Now you write another physical law, say, div E = rho/epsilon0 and define

U2 = (div E - rho/epsilon0)^2

which you might call "the Gaussian unworldliness of electricity." You continue to write U3, U4, and so on -- one for every physical law there is. Finally you call the total unworldliness U of the world the sum of the various unworldlinesses Ui from all the sub-phenomena that are involved; that is, U = Sum over i of Ui. Then the great "law of nature" is

U = 0

This "law" means, of course, that the sum of the squares of all the individual mismatches is zero, and the only way the sum of a lot of squares can be zero is for each one of the terms to be zero. So the "beautifully simple" law is equivalent to the whole series of equations that you originally wrote down. It is therefore absolutely obvious that a simple notation that just hides the complexity in the definitions of symbols is not real simplicity. _It is just a trick_. The beauty that appears in [the above equation] -- just from the fact that several equations are hidden within it -- is no more than a trick. When you unwrap the whole thing, you get back where you were before."

I recall (somewhat vaguely) that Feynman made other similar statements in places other than the Feynman Lectures, but unfortunately I don't have time to research that now.

The bottom line, as I see it, is this: there is no overall unity in nature, at least not as the physicist sees the world. There are _some_ things, such as heat and mechanical energy, electricity and magnetism and light, the weak (nuclear) and electromagnetic fields, once thought to be completely different things, which were later subsumed under a single unifying theory, but then there are also a lot of loose ends, so that any attempt at an overall unified point of view, given our present knowledge, requires one to ignore the loose ends and/or to make an artificial synthesis. [Another good example of some things that seems not to be unified in nature, which disappointed Einstein immensely, are electromagnetic and gravitational phenomena. Of course these days we have string theory, which subsumes these and all other known fields; the only problem with that theory is that it has absolutely no experimental verification, and therefore (in my mind at least) it has a similar status as Ptolemy's epicycles had at the time of Ptolemy.]

Best regards,
Mike

Joe said...

Dear Mike

Thank you again for contributing to the discussion.

Recognising that Feynman himself does not do it, can one suggest that the imperfections in symmetries are flagging up an area where physics has more to learn (about symmetry)? [Feynman does, I think, acknowledge that physics always has more to learn.]This would allow an understanding of conservation laws as indicating some degree of unity (or, at least, connections) within nature. This seems to me to be at least as possible an approach to take when presented with the physics as that taken by Feynman (which seems to be one of turning away from the possibility of unity in favour of a kind of agnosticism with regard to that possibility).

What I am interested to try to put my finger on is the exact driver for Feynman in taking his position on unity (and one or two other things), and I don't feel I have quite managed this yet. In this regard, I was particulary struck by the fact that the quotations you offer are from the Lectures on Physics - ie from Feynman's physics teaching.. My next post on Feynman might be delayed while I do some more reading ...Amazon delivered me a package with some new books yesterday ...

Michael A. Gottlieb said...

Dear Joe,

While it is certainly true that physics has more to learn, the imperfections in symmetries that Feynman discusses are not due to incomplete knowledge; they are well-established fact. For example, consider parity: this symmetry, long believed to be perfect, dictates that if some physical thing is possible, then its reflection (in a mirror) is also possible. Thus, for example, if a physical object or process has right-handed chirality, conservation of parity informs us there is also the possibility of a similar object or process with left-handed chirality. However, it is found that for certain processes involving weak nuclear interactions, this is not so - for these processes only the right-handed (or left-handed) version is possible (but not its mirror reflection). The "break" in this symmetry can not be "fixed" by a more complete knowledge of symmetry.

The term "agnosticism" (from the Greek) means "without knowledge" and I think that is an apt description of the frame of mind that good scientists take in approaching some part of nature that they do not know about. In other words, their minds are open. On the other hand to approach nature with a preformed idea - whether it is of unity or anything else - and then to expect or demand that nature conforms to this idea is the very antithesis of science.

The essential difference between a scientist and a religionist is this: The scientist admits he knows nothing, except what he observes and what he can reason directly from his observations. The religionist has faith in something (for example, god or unity, or the bible), and imposes this on his observations and his reasoning.

I hope your package from Amazon includes the Feynman Lectures on Physics!

Best regards,
Mike