Re: Richard Feynman's "QED"
- From: Bob Cain <arcane@xxxxxxxxxxxxxxxxx>
- Date: Sat, 17 Sep 2005 13:01:37 -0700
William Sommerwerck wrote:
Bob Cain's admonishments finally got me to read Feyman's "QED". I strongly recommend it to everyone in this group. Especially the first chapter, which briefly discusses the philosophy of science. <ahem>
Fun stuff. One of the coolest reads in my library. Completely approachable by a layman.
QED is an attempt to come up with a single coherent theory that describes
both macro and micro effects. As such, it seems to work extremely well. The
problem with Bob's claim is that pesky little timer. The timer introduces
phase into the theory -- and phase is a property associated with waves, not
particles.
Every particle has a frequency of oscillation as proposed by DeBroglie and verified by experiment. Anything that oscilates has a phase.
Feynman -- who explicitly states that light (EM radiation) is "really" a particle -- doesn't directly address the point that a theory (in his view) treating EM energy as being "particulate" has a timer attached to it. The timer seems to be necessary if you're going to account for wave-like effects, but Feynman seems to be trying to sweep this necessity under the rug. **
LOL! He was very good at that. Renormalization, which he invented, is just such a sweeping (of infinities no less.) He suspects that it isn't valid math but it works to amazing precision anyway.
He also admits that the path integral or "sum over histories" which is the basis of his formulation of QED and his path to the Nobel prize is on shaky mathematical grounds. It still works amazingly well, and Feynman Diagrams, schematics for path integrals, are on every particle physicist's blackboard regardless.
He also contradicts what I've read in so many books on physics (which doesn't make it true, of course), that light is neither a wave nor a particle -- it just looks like one or the other, depending on the experiment. "QED" also neglects to cover this point -- Feynman doesn't explain (as far as I could tell) how (or whether) QED theory predicts this.
That would require going to a mathematical depth inappropriate for the audience to which that book speaks.
Oh, one other thing... If I don't say this, it's inevitable someone is going to deliberately misread what I wrote... I do not claim or imply that QED is incorrect in any way, or does not produce useful results. I am simply commenting on how Bob Cain and Richard Feynman have described it. I'd like to see a deeper discussion of the points I've covered.
Never before, and probably never again, have my name and Richard Feynman's been joined by an "and." You just made my day! :-)
** Feynman says that these lectures on QED give a correct, but not necessarily complete, description. Okay. No problem. I do wish he'd explained the rationale of the timer, though. It makes sense to me that it should be needed; I just wonder why he left out any discussion.
Didn't he mention DeBroglie's equation?
Bob --
"Things should be described as simply as possible, but no simpler."
A. Einstein .
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