Does an electron moving along a geodesic radiate?

[cosmik debris]

This is indeed an interesting question, even the premiss that accelerating charges radiate seems debatable. Some authors say that linear acceleration is not enough and there has to be some sort of repetitive motion. I found this article one of the better discussions on the various ideas.

http://mathpages.com/home/kmath528/kmath528.htm

 

[PAllen]

This is indeed an interesting question, even the premiss that accelerating charges radiate seems debatable. Some authors say that linear acceleration is not enough and there has to be some sort of repetitive motion. I found this article one of the better discussions on the various ideas.

http://mathpages.com/home/kmath528/kmath528.htm

I am generally a fan of mathpages. However, the following statements involve several of the confusions I got at in my prior post:

"For example, a charged object at rest on the Earth's surface is stationary, and yet it's also subject to a (gravitational) acceleration of about 9.8 m/sec2. It seems safe to say (and it is evidently a matter of fact) that such an object does not radiate electromagnetic energy, at least from the point of view of co-stationary observers. If it did, we would have a perpetual source of free energy. "

(I should also note that a question about this very area was my introductions to physics forums, where I found two peer reviewed, puplished papers from 2010 coming to opposite conclusions about issues related to this. Even more interestingly, the one most disputed here was the more professionally reviewed one, published in Annalen der Physik. The other one was published in a journal for science teachers.).

The problem with the mathpages quote above is that classically, there is no problem with conversion of mass/energy to radiation. Classically, the process of an electron sitting on a planet radiating could amount to continuous conversion of the mass of the planet to radiation, the process assymptotically stopping when the mass is exhausted (and then there is no more proper acceleration producing radiation). Quantum mechanically, one has completely different expectations - just as continuous instability of atoms predicted classically is wrong, such continuous radiation of for a stationary (but properly accelerating) charge is subject to limitation. Yet further complication is that there is no *exact* formulation of QED+gravity; and the classically predicted effects are *many* orders of magnitude too small to detect - so experimental observations are irrelevant.