Does the equivalence principle hold for charged particles?

Thread starter pianoplayer
Start date Apr 18, 2005
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Charged Charged particles Equivalence Equivalence principle Particles Principle

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The discussion centers on the equivalence principle (EP) and its implications for charged particles, particularly regarding radiation. While the EP suggests that one cannot distinguish between an accelerating frame and a uniform gravitational field, it raises questions about whether a stationary charged particle in a gravitational field would radiate, which it does not appear to do. Participants debate whether radiation is frame independent or dependent on the observer's acceleration, with references to conflicting papers by Shariati and Parrott. The consensus leans towards radiation being frame dependent, as an observer co-accelerating with a charged particle would not detect radiation, while an observer in a different frame might. Overall, the topic remains complex and unresolved, highlighting the challenges in reconciling electromagnetism with general relativity.

Apr 25, 2005

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pianoplayer said:

I'm inclined to go along with you guys (e.g., Qoo and Chronos) who argue that no radiation is seen by an observer accelerating with the charge. Here's a question: from a purely classical perspective, could one look at the problem as follows. The observer who's accelerating with the charge will see a static electric field -- no time dependence, no retarded potentials, and thus no radiation. Now a guy floating in space sees this accelerating charge move past. From his point of view, the electric field is not static. Could one sit down and do the calculation to show that he sees time-varying (transverse) components of an electric and magnetic field with a non-zero Poynting vector, i.e., EM radiation. If this can be demonstrated, it seems this would settle the argument without resorting to arguments about "fuzzy" particles, etc. Or perhaps it's not this simple.

http://xxx.lanl.gov/abs/gr-qc/0006037

goes through this calculation, though I really have only glanced at it.

To write the Poynting vector at Rindler instant \mbox{\omega_0} for the local observer who is
seated at (Xo, Yo,Zo), we can write everything in the instantaneous rest frame of the
source S at the retarded time and then use the Lorentz boost that transforms this frame
to the instantaneous rest frame of O (at the moment of observation).

They find that an accelerating observer sees only a pure electric field, and hence no Poynting vector.