Gamma Rays: How High is High?

Great Question. Here's my guess (and it's probably wrong). Since the Planck Length is the smallest meaningful unit of length:

meter

and the energy of a photon is

E = c·h/λ

where λ is the wavelength

If we assume the smallest wavelength with any meaning is the planck length, then the corresponding energy would be:

E = (c · h)/1.62 x 10^-35 m = (1.99 x 10-25 m·J / 1.62 x 10-35 m) = 1.23 x 10¹⁰ Joules

Now 1 GeV = 1.6 x 10^-10 joules, so 1.23 x 10¹⁰ Joules would be 7.6 x 10¹⁹ GeV

From a practical standpoint, I don't think any known gamma rays come anywhere close to that (I think 10³ GeV is the max detected, but I could be very wrong about that).

Thanks.

Energies of >350 GeV have been found, see http://www.citebase.org/abstract?id=oai%3AarXiv.org%3Aastro-ph%2F9712325