When light is released from a faraway star (that is, most noticeably a faraway star), the wavelength is stretched due to the expansion of the universe. The photons/light wave lose energy in that context. I have heard some claim that within GR, this is an example of a violation of conservation of ...

Has Hooke Law force is proportional to extension got a mathematical proof from quantum mechanics and how atomic bonds behave?

I have one idea, but I'm not sure it's true. According to Newton's second law, we have: $$ F_{ext} = \sum m_i \cdot a_i \tag{1}$$ (where $i$ denotes all the particles of the system), or: $$F_{ext} = m_T \cdot a_{cm} \tag{2}$$ where $m_T$ is the total mass of the system and $a_{cm}$ the accelerati...

If there was a very tall object suspended just above the ground the force of gravity acting on a nominal sized section of it would be higher near the bottom than at the top. Would this increase the tension within the object? Now stand the object on the ground. The force within the object has chan...

Consider ideal gas confined in an adiabatic container. We know that internal energy does not depend on the velocity of a uniformly moving system, because relative to the walls of the container, the effect of uniform motion is cancelled, hence pressure does not depend on the uniform motion and the...

I want to calculate $\langle n | \partial_{k_x} n \rangle$ where $| n \rangle \equiv | u_{n,\mathbf{k}} \rangle $ is the $n$-th Bloch eigenstate of a $6\times6$ Hamiltonian $H\equiv H(\mathbf{k})$. The wave vector $\mathbf{k}$ lies inside the first Brillouin zone (BZ). Due to the nature of $H$, I...