Note 36 — Chapter X · THE NEW QUANTUM THEORY
Reading edition
The probability is often stated to be proportional to instead of , as assumed above. The whole interpretation is very obscure, but it seems to depend on whether you are considering the probability after you know what has happened or the probability for the purposes of prediction. The is obtained by introducing two symmetrical systems of -waves travelling in opposite directions in time; one of these must presumably correspond to probable inference from what is known (or is stated) to have been the condition at a later time. Probability necessarily means “probability in the light of certain given information”, so that the probability cannot possibly be represented by the same function in different classes of problems with different initial data.