Help Finding Source of Feynman Quote

[JPBenowitz]

Homework Statement

I don't really know where to post this but I chose this section. I need help finding the source of this Feynman Quote "The probability of detecting a photon at any point is the sum of all the probabilities of the photon being detected at that point by any path"

Homework Equations

The Attempt at a Solution

 

[fzero]

It might be from his popular lectures on QED:

http://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Light_and_Matter

If that exact quote isn't there, the concept itself is explained at a very basic level.

 

[phinds]

]... I need help finding the source of this Feynman Quote "The probability of detecting a photon at any point is the sum of all the probabilities of the photon being detected at that point by any path"

Since this is one of his fundamental principles, he said it many times and very likely wrote it many times as well.

 

[TSny]

If that's a direct quote, then he must have been speaking loosely. It's the probability amplitudes for all the paths that are added to get the total probability amplitude. You then "square" the total amplitude to get the total probability. The distinction between adding amplitudes and adding probabilities is fundamental to quantum mechanics.