Recent content by LarryC

(Simplified version of Baym, Chapter 19, Problem 2) Calculate, to first order in the inter-particle interaction V(r-r'), the energy of an N+1 particle system of spin-1/2 fermions with on particle of momentum p outside an N-particle Fermi sea (quasiparticle state). The answer should be expressed...

Thanks for the great reference! I am just wondering if I can get something related to the harmonic oscillator from out of the approximate form $$ \bigg[\frac{L^2}{2ml^2}+\frac{1}{2}mgl\theta^2\bigg]\psi = E\psi $$ This looks like a harmonic oscillator, but ##L## contains both ##\theta## and...

I have trouble with finding the eigenstates of a spherical pendulum (length $l$, mass $m$) under the small angle approximation. My intuition is that the final result should be some sort of combinations of a harmonic oscillator in $\theta$ and a free particle in $\phi$, but it's not obvious to...

(a) and (b) are fairly traditional, but I have trouble understanding the phrasing of (c). What makes the infinite dimensionality in (c) different from (a) and (b)?

Yep I understand this. But what confuses me is the huge difference between the classical theory and the relativity when calculating the frequency. I mean, for example, consider a particle moving at a low speed. Then f=E/h gives either f=mc^2/h from relativistic perspective or f=mv^2/(2h) in...

According to de Broglie's hypothesis, the matter wavelength could be described by lamda=h/p. But which momentum, the classical p=mv, or the relativistic one p=mv(1-v^2/c^2)^(-1/2) should be used in this equation? Additionally, an even more confusing issue to me is regarding the other relation...