Most active questions

Would a Betelgeuse supernova be a hazard to the ISS? I know people on earth would be safe but what about people on the ISS? What about satellites in space?

It seems this has been discussed here previously (e.g this and this post), but I still feel uneasy. Essentially, I think it all boils down to the popular interpretation of the scalar field operator in ...

$H=I^2Rt\implies H\propto t$ okay, but let a maintenance system ensure continuous identical flow system of electric current conserving I²R approximately over a long time, say years (practically ...

Question 1: is it always possible to write the metric in that form? Is it sufficient the local conformally-flat form to obtain the volume? Question 2: Is the volume form in (4.1) well-defined? Going ...

Could somebody please explain why the convention for the Bloch sphere of a qubit has the $|0>$ state pointing up and the $|1>$ pointing down? I understand that the Bloch sphere representation ...

I have a few questions about principle how van de Graaff generator works. To avoid confusion I will use numbering from the wiki picture: [ADDED LATER #1] See also here for nearly identical ...

According to the Lorentz transformations, if an observer $O'$ moves at a relative velocity $\beta$ with respect to another observer $O$, the proper times $t$ and $t'$ would be related by: $$ t=\sqrt{1-...

Imagine inviscid, incompressible steady-state fluid flow around a cylinder like in the diagram below so that it flows around the cylinder symmetrically about the x-axis: According to the no-slip ...

I am trying to figure out following statement: For noble metals, the free-electron picture would predict that the Fermi sphere does not reach the boundary of the first Brillouin zone. In reality, ...

Pauli repulsion and Bose--Einstein condensation (BEC) arise from quantum statistics and are not considered fundamental forces. That is, they are neither gravitational nor electrostatic in nature, ...

I am trying to practice the techniques given in the book "Feynman Integrals: A Comprehensive for Students and Researchers," by Stefan Weinzierl (preprint). I am getting stuck on one point ...

In standard electrodynamics $$\mathbf{E}=\mathbf{E}_\parallel+\mathbf{E}_\perp$$ $$ \begin{eqnarray} \mathbf{E}_\parallel&=&\frac{1}{4\pi}\int\frac{\rho}{\varepsilon_0}\frac{\hat{\mathbf{r}}}{...

What is the relativistic equation capturing the equation of motion of an electron going through the Stern-Gerlach experiment in classical mechanics? After some googling it seems I'm after a derivation ...

I have a very basic confusion about the 2D random-bond Ising model on a square lattice with Boltzmann weight $$\omega(J_{ij},\sigma_j)=\prod_{ij}(1-p)^{\delta_{J_{ij}=1}} p^{\delta_{J_{ij}=-1}} e^{-\...

if you write the recurrence as a homogeneous linear system $A\mathbf x=0$, a necessary and sufficient condition for proportionality of (nonzero) solutions is that $\dim\ker A=1$. For a simple ...