When Feynman refers to the "top surface" and "bottom surface" probabilities when explaining QED, is he referring to the probability of the photons reaching the top of the object and the bottom of the object?

  • $\begingroup$ Which reference? Which page? $\endgroup$ – Qmechanic Dec 9 '14 at 18:45
  • $\begingroup$ In his book QED, when he is explaining the oscillating probability of photons reflecting from glass depending on thickness. $\endgroup$ – user1939991 Dec 9 '14 at 18:48
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    $\begingroup$ I think he's talking about Feynman's QED: The Strange Theory of Light and Matter. It's in the first or second chapter. But I think yes, Feynman's referring to the top and bottom surface of an object. An even better example would be oil spread over the surface of water. Then the upper surface of the oil in contact with air would be the "top" surface, while the lower one, in contact with water, would be the bottom surface. As far as I can remember, the experiment explained is very similar to this, and Feynman is explaining interference with his reasoning with arrows indicating probabilities. $\endgroup$ – user3237992 Dec 9 '14 at 18:52
  • $\begingroup$ Okay, thanks a lot, that was the exact reference I was referring to! $\endgroup$ – user1939991 Dec 9 '14 at 18:56

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