Is there any limit for the energy of a photon? (extended)?

Question

Please check up also the question from Mik_K:
" What is the highest frequency of light, and why?"

I thought, a photon gets unstable at some frequency(-enrgy)-limit and decays into elementary particles like it happens in the immediate vicinity of a super massive nucleus (decay of vacuum, huge em-fielddensity). Is this right?
And, must a possible limitation on the energy of a photon be nessecerilly explained by plancks length? I guess, Einstein would give a quantummecanics-free explanation on this issue.

Answer 1

Practically speaking yes, the limit is due to the processes needed to create the photons.
At the moment the highest known energy photons are the Gamma rays that are created by the colapse of a very big star into a black hole.
Energys of gamma rays exceeds 1 Meg eV. When these highly energetic photons hit a small particle like an electron they may cause spontaneous particle creation.

Answer 2

Yes, there is...basically as you alluded to....when the energy of the electric field exceeds that which is necessary to induce pair production from the quantum vacuum....as expalined by Quantum Electrodynamics.

Yes, we have evidence when high E fields in over critical nuclear numbers creates the 'critical vacuum' which spontaneously goes into pair prduction.

General Rel.doesn't account for such things for light ....however extreme gravity at the horizon of a black hole does a similar thing. (See Hawking)

Answer 3

There is no limitation on the frequency or energy of light. It can be literally anywhere on the interval

(0, infinity)

not including either endpoint, of course.

Answer 4

There is a limit to everything whether extended or not.