Recent content by mattlorig

Thanks I'll check that book out.

Is there a nice paper on the internet, or a good book that describes (hopefully in simple terms) how to take a Lagrangian and write down: 1) vertex factors 2) the propagators in momentum space and position space? (does anybody ever do calculations in position space? if not, forget about the...

L_int = lambda ( phi d_mu phi d^mu phi + m^2 phi^3 ) This topic seems to be right up my ally at the moment. Hopefully somebody can strighten me out. I'm dealing with spin zero bosons Suppose L_int = lambda ( phi d_mu phi d^mu phi + m^2 phi^3 ) my vertex is drawn with momenta k1, k2, and...

I just finished reading Sakurai's treatment of feynman's path integral, and I'm left feeling really stupid. So the integral gives the propagator, which represents a transition amplitude. I'm left wondering what we use that for. Perhaps I'll understand when I start working some problems, or...

If you are really interested in all three, do all three. But, if at some point your interest drains in one or two of your majors, don't hesitate to drop it. I did a spanish and physics double major as an undergrad. Basically, I did the spanish major because I thought it would be easy (I had...

I will begin physics grad school this fall. I am pretty well decided on studying condensed matter theory. But, within CM theory, I'm not sure which area I should choose. On one hand, there are three professors at my school who mainly use field theory to solve many body problems. Ideally...

Thanks Daniel for the help. I will find the 3rd order approximations to ca and cb today. I think my main mistake was just not realizing why ca_1 = 1. Now that that's clear, the rest should be fairly simple. Also, after doing a bit more research, I found this method in my old Diff Eq book...

p 302 of the (my book is black...I think it's the second newest edition). Griffiths does say "ca_2 includes the zeroth order term; the 2nd order correction would be the integral term alone". But, I think griffiths use of ca_n is ambiguous here. In any case, I'm pretty sure that if I just...

because the integral of zero is zero.

Maybe I should clarify my question. Regarding the method of successive approxiamtions griffiths talks about in time dependent perturbation theory, is ca = SUM (ca_n) = LIM {ca_n} ? Hopefully that's easier to understand than my first post.

In chapter nine of Griffiths' Quatum Mechanics text, he talks about the method of succesive approximations as a method for solving a two level system in time dependent perturbation theory. d(ca)/dt = f(t) cb --> ca_n = int[ f(t') * cb_n-1, dt', 0 t] d(cb)/dt = g(t) ca --> cb_n = int[ g(t') *...

This past fall I ordered a few of my books from internet vendors who sold softcover international editions of textbooks. For this first time in my college career, I spent less than 200 bucks on my texts, and they were exactly the same as the rather pricey hardcover books my buddies had...

Okay, I feel really dumb, because this seems like something I should know, but I don't. So, here's my question. Suppose I have d2y/dx2, x = x(z), and z = z(x) How do I find d2y/dz2? Here's what I did: dy/dz = dy/dx * dx/dz d2y/dz2 = d/dz ( dy/ dz ) = d/dz (dy/dx * dx/dz) = d2y/dx2 *...

At this point, since you are undecided as to what to do, my advice would be to not close any doors. If you do an undergraduate in physics, you can still get an Masters in EE. Plus, if you find that physics is your cup of tea, you can go on to get that PhD in physics. On the other hand, if you...

Now that the April 15th deadline has passed, I thought it would be a good idea to find out where all the new graduate students have decided to study. That way, you might be able to find other students going to the same school as you. I chose UC - Santa Barbara. If anybody else is going...