What makes sense about a probability that can take on negative or complex values and collections of which don't sum to 1? Convention is no excuse for bad termin

What makes sense about a probability that can take on negative or complex values and collections of which don't sum to 1? Convention is no excuse for bad terminology or notation, especially for beginners to the subject who may not have the math or physics background to appreciate the connection with the continuity equation. You lose nothing by removing the word "probability" and avert possible confusion. "Amplitude" and either "squared modulus" or "amplitude density" work fine. I think Feynman's QED is mandatory reading for an intro to quantum thinking (and Feynman in general is fantastic). I also think his several comments on wave v. particle indicate another abuse of conventional terminology. Sometimes he'll insist light is not a wave but a particle, but it's actually a screwy kind of particle and you need to think about arrows and paths. ("Collapse" is another word that'd be better off going away...) My favorite beginner-level approach to QM nowadays, at least for beginners who are familiar with linear algebra, is actually Scott Aaronson's (edit: who is an expert in the field, and I believe has even commented on some of Eliezer's quantum posts...) (quantum) computer scientist approach: http://www.scottaaronson.com/democritus/lec9.html http://www.scottaaronson.com/democritus/lec9.html It introduces QM as "What if we tried to make something like probability theory but allowing negative or complex values?" It wouldn't be probability, but it would be like probability. Once you set up the math, the usual "weird" quantum effects of experiments can be shown as a direct consequence of the math.