Electron in Earth Orbit: Does it Emit Radiation?

[yogi]

Does an electron in circular Earth orbit emit radiation?

 

[Garth]

A good question, similar to the question: "Does an electron 'sitting' on a laboratory bench emit radiation as by the equivalence principle it is accelerating upwards at an acceleration g?"

If the answer to the orbiting scenario is 'yes', then the electron might be expected to spiral inwards to conserve energy; however where does the energy of radiation of an emitting supported electron on a lab bench come from?

Garth

 

[Meir Achuz]

yogi: Yes. An e in Earth orbit behaves classically because its radial quantum number is so high. It would emit what is called Larmor radiation at the rate:
P=2e^2 R^2 \omega^2/3c^2. (This is in Gaussian units.)
You can put numbers into see that this radiated power is tiny.

Garth: The EP does not hold for radiation by electric charges.
There is another post about that today.

 

[Garth]

Garth: The EP does not hold for radiation by electric charges.
There is another post about that today.

Why not? It would seem logical to expect that all physical processes within this universe's space-time would be subject to the the geometric effects and principles of GR.

There has been dicsussion on this subject on these Forums some time ago.

Garth

 

[yogi]

Seems the references cited in the other thread support the notion that 1) an electron in freefall will radiate, and 2) an observer comoving in the freefalling frame does not see the radiation? So unless there is some identifiable local physics that tell the electron in free fall when and how to radiate - the radiation must be due to a global property. If we place a charged spherical capacitor in orbit we should expect to detect radio frequence signals? - what about a charged parallel plate capacitor?