Recent content by MWBratton

I think you are correct, but let me pose my confusion as a slightly different question. Sticking with the "Newtonian" formalism, the governing dynamical equation (Which one solves for particular physics problems in order to obtain equation(s) of motion) is \dot{\vec{p}} = - \nabla...

Yeah, I know photons (particles) don't have brains :) but it brings out a certain point of view. What happens when you take a "final point" which is off the particle's classical trajectory? Like you say, if you happen to know of a future point which the particle will travel through, (or you...

I think in 1) I am wondering about what happens in the limit as your "final point" becomes infinitesimally close to your "initial point," as you effectively "shrink" the length of the classical path q_{cl}(t) by considering smaller and smaller motions of the particle.

"The" Classical Path, QM Path Integrals and Paths in Curved Spacetime Hey Guys! I've got an exciting question! It's been burning on my mind for years, but I think I can formulate it now. It's not so much a specific question, but rather a physical story which perhaps this thread can uncover...

I understand "antiparticles moving backward in time" as a crude way of putting what is really going on. Relativity of simultaneity says one cannot tell the order of two events which are somewhat close together: Something like "Feynman vertex (1) emitted W+ which was, a short time later, absorbed...

thanks

Explain "crossing" without invoking QFT? Hi there For someone learning particle physics for the first time (Griffiths' intro book, no knowledge of QFT yet): Why can you "cross" a reaction? Is there an intuitive answer or does one truly need understanding of scattering amplitudes, quantum...

Go easy on the page turning, especially while flipping forth and back in the reference material at the very beginning or end of the book. Seems like Griffiths likes to use some or other bad combination of paper material and book binding. In both this text and his Quantum Mechanics text, seems...

Go easy on the page turning, especially while flipping forth and back in the reference material at the very beginning or end of the book. Seems like Griffiths likes to use some or other bad combination of paper material and book binding. In both this text and his Elementary Particles text, seems...

Cool, thanks! Wow, fast response time

Greetings PF! This is my first post... I keep reading over and over again either "... so and so mediator is massive. Therefore, its interaction is of finite range" or the converse or "... mediator is massless... its interaction is of infinite range..." Makes sense intuitively (inertia?)...