Recent content by Philethan

Oh! Haha. I'm so stupid that I didn't see it. Thank you so much! I understand it now :D

Well... Hmm... I'm not sure, but he also said "the plane waves (4) constitute a complete set of orthonormal functions, that can be conveniently used as an expansion set." Does that mean substitute ##W_{k}(x)## into (1) is correct? =0=

Do you mean the resistivity along any direction? Something relevant would be...

I'm reading Mermin's Solid State Physics, chapter 12: The semiclasssical model of electron dynamics. I know the current density from the ##n## band is $$ \mathbf{j}=(-e)\int_{\text{occupied}}f(\epsilon_{\text{n}}(\mathbf{k}))\frac{d\mathbf{k}}{4\pi^3}\mathbf{v}_{\text{n}}(\mathbf{k}). $$ In...

In Grosso's Solid State Physics, chapter 1, page 2, The author said that: Therefore, I plug (4) into (1), and I expect that I can get the following relationship, which proves that ##H\left|W_{k}(x)\right\rangle## belongs to the subspace ##\mathbf{S}_{k}## of plane waves of wavenumbers...

Thanks so much. I found it doesn't show normally in Safari, but it's good in Chrome. Please help me check if there's something wrong with backend settings. Thank you so much :D Here's my screenshots. It's Safari: And it's Chrome: Thank you so much!------------[Update]------------It works in...

(Oh my god, why can't my post show normally? Some sentences just disappear, but I can still see them while editing. It's very weird. Can someone help me? I've reported.)I know only partially filled bands result in current density, and I think there must be not only 2 partially filled bands, but...

Homework Statement Two observables ##A_{1}## and ##A_{2}## which do not involve time explicitly, are known not to commute, ## [A_{1},A_{2}]\neq0, ## yet we also know that ##A_{1}## and ##A_{2}## both commute with the Hamiltonian: ## [A_{1},H]=0\text{, }[A_{2},H]=0. ## Prove that the energy...

Thanks a lot! It really helps!

Hello, every one! I'm 26 now. I majored in Chemical Engineering and graduated from National Taiwan University. Then I applied college again (major in physics now) to fulfill my dream ---- be a philosopher of physics. Now, I'm senior. I've studied the quantum Physics, thermal physics, classical...

In my opinion, "D" represents the displacement of the action point on which the force act, rather than the displacement of the "center of the mass". In the case of walking, the work done by the static friction is zero although the displacement of center of mass of man is not zero. Therefore...

WOW...it's inspiring to see a real person who have done what I want to do in the future. But I'm wondering if it's necessary to get a Ph.D. in physics? Or... maybe I should say that it's unnecessary if I can express my ideas using physicist's language, clear mathematical deduction and...

Thank you so much. In fact, the only one related philosophy course in my university is philosophy of science. And...perhaps, it's also the only one related course in Taiwan. Ok, I'll try to face the music. If I really want to be an influential philosopher of physics, then I must have actively...

I'm Taiwanese and 25. I'm deeply interested in philosophy of physics since I read "An Introduction to philosophy of physics" written by Marc Lange 3 years ago. I majored in Chemical Engineering in National Taiwan University(NTU) at that time. After graduated, I apply for the department of...

Really? Even if some of the ice is melting, the two are still in equilibrium? So... What's the definition of equilibrium? It seems that the exact definition of equilibrium is "the system is at equilibrium if and only if its entropy is a maximum". Is that correct? Thank you very much :)