This question is about some reply by John Baez on sci.physics.research
the article he is talking about is this one: http://xxx.lanl.gov/abs/gr-qc/0106075
the question itself is pretty simple. In that reply, which i'll quote for completeness, reads:
Unruh says that Haisch and Rueda's calculations are wrong, and that a correct calculation shows a uniformly accelerating observer zipping through the vacuum state of a quantized electromagnetic field on Minkowski spacetime sees a *perfectly thermalized* bath of photons. In particular, this means such an observer will see no "Rindler flux" - i.e., the expectation value of the Poynting vector is zero. Or in less fancy language: there will be, on average, no net flux of momentum in the photons seen by the accelerating observer. He gives a very simple argument showing that the expectation value of the Poynting vector *must* be zero: the whole situation is time-symmetric, and time reversal flips the direction of the Poynting vector!
Now, i don't understand at all that last symmetry argument. Yes, time inversion will reverse direction of real vectors, so? an accelerated particle has a definite acceleration vector, that is reversed under time inversion, and is not zero. Why would any Poynting vector be zero?