This World Wide Web page written by
Dan Styer,
Oberlin College Physics Department;
http://www.oberlin.edu/physics/dstyer/StrangeQM/FeynmanClearUp.html;
last updated 21 June 2012.
Page 14, paragraph beginning "The human eye is a very good
instrument . . .":
A discussion of light reception by the human eye is
F. Rieke and D.A. Baylor, "Single-photon detection by rod cells
of the retina,"
Reviews of Modern Physics 70 (July 1998) 1027-1036.
Page 15, paragraph beginning "I want to emphasize that light
comes in this form . . .":
I think that Feynman makes a pedagogical error here
when he insists that light is a particle. True, one always
gets correct results by considering light to be a particle:
not as a familiar classical particle like a marble, but as a
strange quantal particle that, for example, might not have a
position. However, the word
"particle" so strongly suggests the classical marble that
this passage gives the wrong impression. I far prefer the way
Feynman himself treats the same issue in "The Character of
Physical Law" (MIT Press, 1965, page 128):
| Now we know how the electrons and light behave. But what can I call it? If I say they behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way, which technically could be called a quantum mechanical way. They behave in a way that is like nothing that you have ever seen before. Your experience with things that you have seen before is incomplete. The behavior of things on a very tiny scale is simply different. An atom does not behave like a weight hanging on a spring and oscillating. Nor does it behave like a miniature representation of the solar system with little planets going around in orbits. Nor does it appear to be somewhat like a cloud or fog of some sort surrounding the nucleus. It behaves like nothing you have ever seen before. |
Page 38, paragraph beginning "We start with a mirror . . ."
(see also figure 19 on page 39):
Feynman's light source is (potentially) sending out photons
in all directions, like the filament in a light bulb and
unlike a spotlight or a laser that
sends light out in only one direction.
Page 87, paragraph beginning "As for the time scale . . .":
Feynman's time T is what we would normally call "ct",
where c is the speed of light and t is the time measured
in seconds.
Pages 87-91, amplitudes for the first two basic actions:
Here is a technical discussion.
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Pages 115-118, magnetic moment of the electron:
Here is an update and elaboration.
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