1:20 AM
1

Suppose 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…
2:57 AM
1

I 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...

3:22 AM
1

An 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…
10:40 AM
1

When 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…
7:38 PM
2

Suppose 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...