Is there a clearer analogy for Feynman's electron-photon interactions?

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Offline PAOLO137

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In the otherwise interesting book QED, Richard Feynman, intended to be understood by people having a good level of scientific knowledge but not scientists by profession. He introduces his famous graphical way of rendering the electron-photon interactions, and associates to each particle what he calls a "watch"  which is not really a time measuring device but simply a dial with one hand. What I have understood is that these "watches" may change their
dimension, becoming smaller as the probability amplitude of finding the particle in that place becomes smaller. Instead I haven't understood the meaning of the hand moving backwards as the particle travels in space.
I found the same description in another interesting and clear book by B.Cox and J. Forshaw :The quantum universe:
everything that can happen does happen. (Penguin books).
I understand that Feynman did not find a better way of explaining some very difficult concept, but the trick of the
watches is very unsatisfactory. I imagine that the size of the watch may correspond to the amplitude of a wave,
and the position of the hand could be something relevant to the phase of the wave. In any case I would know if somebody is capable of explaining more clearly this picture. Many thanks, Paolo de Magistris (Physicist).
« Last Edit: 17/10/2012 08:38:15 by chris »
Paolo de Magistris

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Offline yor_on

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Re: QED lectures by Richard Feynman
« Reply #1 on: 16/10/2012 18:56:06 »
Are you thinking of Feynman many paths? 'Sum over Histories' as it is called.
http://www.thenakedscientists.com/forum/index.php?topic=38243.0
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Offline PAOLO137

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Thanks a lot for your answer. Now something awkward happened to me :
I went to the address quoted by you and found a very interesting and clear
paper which i planned to read later. I forgot to save it somewere on my PC.
Now I went back there and probably the same location had been used for
a different subject. Can you help me to find the original paper? Thanks again,
Paolo.
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Offline yor_on

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Sorry Paolo, don't know what paper you refer too?
As for that paper it may be saved in your 'temp directory', I hope, but it will be a detective work to find it, easier if it was a '*.pdf' though
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Hmm.. didn't download it you say :) But maybe you opened a pdf? If so you might find it, but it won't have the same name..
« Last Edit: 29/11/2012 18:38:53 by yor_on »
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Offline PAOLO137

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Terrific. I remember reading two pages of it. I was so happy because I began understanding something which was very obscure to me until that time. Now is lost. I must learn from this experience. Computers and the net may behave as quicksand sometimes. I thank you a lot anyway for your kindness. Paolo
Paolo de Magistris