In every situation I'm aware of, energy states exist because of some force that gives rise to them (dE/dx, y'know). What force did Dirac envision as giving rise to his proposed negative energy states (from which antimatter arises)? When I see it described in textbooks, the states are shown as...
There is a very good article on this subject from American Journal of Physics: Hans C. Ohanian, "What is spin?" 54 (6), 500-505 (1986). I don't know if it is available online anywhere.
Ah, I should have known Churchill could rescue me. Back in the day it always did.
Jeff and Si - thanks for all the helpful posts. Looking back at that stuff, I realize the Wick rotation was the thing that really was bugging me, and that all I needed was a slight clue. And keep lobbying for...
I just realized I said "propagator," when what I really meant was vacuum-vacuum transition amplitude. Sorry for the confusion.
It makes sense to me what you are saying, but looking at Weinberg (I don't own it), his notation is odd to me, and his mathematical treatment so abbreviated it's a...
Are you saying the key is knowing the right answer ahead of time? My complaint is with authors who claim to be doing a derivation - meaning the Wick rotation should stand convincingly on its own logic. I don't necessarily doubt that it does, I just want to see it spelled out so I can...
Well, I would certainly be impressed if Weinberg has a good explanation of how to arrive at the ground state propagator. That is one thing that all authors seem to deal with in the most annoyingly fast and loose terms - never bothering to justify the Wick rotation, and sliding from initial and...
It would be good to have a head count of how many are interested and what texts they have or prefer (is there an easy way to do that here?)
I have not looked at Weinberg in more than a cursory way, and it's big and expensive (3 volumes), so I would have to take the time to convince myself...
I was really enthused about this thread, and hoped I could contribute. But alas, I find Siegel incomprehensible overall. I have had to go back to Ryder and Peskin & Shroeder. If anyone wanted to go through those books (maybe starting with a later chapter so as not to be too pedestrian) I...
There are quite a few experiments that I think show individual particles are superpositions of states. For instance, the double-slit experiment with individual electrons shows the same interference pattern after enough electrons have been put through it one at a time as a full electron beam...
The answer to this question is unknown. Einstein concluded that space-time must be curved by matter/energy (strictly speaking momentum and energy fluxes also contribute to curvature), and he described exactly how much it is curved by a given amount of matter/energy. But his equations give no...
Thanks, that paper is a really good one. I have not gotten all the way through it yet so don't know if it answers the main question, but very useful in any case.
Why is it that when normal ordering the terms in the Hamiltonian for bosons, the commutation rules are ignored, but when normal ordering fermion operators the anti-commutation rules are used to justify a change in sign?
These are both really intriguing statements. Could you give references?
I also remember someone once showing me a transformation that converts Maxwell's equations into complex form, so that they appeared as one equation perfectly analogous to the Schroedinger equation. I think this might...