Recent content by salvador_dali

Whoops, I misread the question. ghwellsjr is absolutely right. The spatial separation in one coordinate system as measured in another is important when considering phase space distributions (otherwise p^0 d^3 x wouldn't be a relativistic invariant), but not here.

The observed separations in position will change for different observers related by Lorentz boosts, but not by the usual length contraction relation (the simple gamma factor). The easiest way to see this is by brute force: write down expressions for x(t) = ... in some frame for each of the two...

Actually, I think I've figured it out (this may be what you were suggesting this whole time): Basically, the 1/d^3 x transforms as a density of particles rather than as a coordinate volume. This is required by the invariance of p^0 d^3 x, and can be shown instructively by observing the change...

Thanks pervect and bcrowell for your thoughts; it does seem sensible to treat the photon as a wave packet and then transform the Poynting flux; that may be what I do. However, I'm still not sure that I think the situation for null dust is fully consistent -- I can set p_A^0 = p_A^1 = E and...

Hi, I'm trying to write down the stress-energy tensor for a single photon in GR, but I'm running into trouble with its transformation properties. I'll demonstrate what I do quickly and then illustrate the problem. Given a photon with wavevector p, we write {\bf T} = \int \frac{\mathrm{d}^3...