« first day (2534 days earlier)      last day (48 days later) » 

HNQ
1:20 AM
1
Q: Is space-like separation transitive?

Anti-TachyonSuppose that events $A$ and $B$ are spacelike separated. Also suppose that events $B$ and $C$ are spacelike separated. Does this guarantee that $A$ and $C$ are spacelike separated? That is, is the relation of spacelike separation transitive? Thank you.

 
 
2 hours later…
HNQ
2:57 AM
1
Q: Commutator of two functions

Kianoosh.kargarI want to compute the commutation relation between a function of momentum and a function of space in Quantum Mechanics. I know the commutation relation between momentum and a function of space but how can I compute the commutation relation between functions of momentum $p$ and space $x$? Some thi...

 
HNQ
3:22 AM
1
Q: Is the electromagnetic wave having a lateral extension?

Mathieu KrisztianAn electromagnetic wave is typically shown with this schematic (taken from https://en.wikipedia.org/wiki/Electromagnetic_radiation ) We see graphically from the schematic that the amplitude of E and B is is evolving with position and time. Thus, should we consider that the electromagnetic wave ha...

 
 
7 hours later…
HNQ
10:40 AM
1
Q: Fourth Equation of Motion

Prof. MeowWhen I was studying motion, my teacher asked us to derive the equations of motion. I ended up with the derivation for fourth equation of motion also. My teacher said this is not an equation. I am asking if this proof is correct for the equation? $$ v^2-u^2 = 2ax $$ $$ (v+u)(v-u) = 2 (\frac{v-u}{t...

 
 
9 hours later…
HNQ
7:38 PM
2
Q: How do length measurements with measuring sticks depend on the metric in general relativity?

anoniemSuppose I have a metric $ds^2 = (cdt)^2 - dx^2 - (Ady)^2 -dz^2$, with A a constant (larger than zero and independent of $x,y,z,t$). Suppose I have a collection of identical measuring sticks. Suppose that I put such sticks along the x-axis ($y=z=0$), one after the other, until the point $x=1$ is r...

 

« first day (2534 days earlier)      last day (48 days later) »