Thread: Photon/ gluon
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Dec4-03, 11:33 AM
P: 383
1100f said: there is no electromagnetic interraction between 2 photons

But, two photons in the gamma range of frequencies, having sufficient total energy and getting close to each other near a massive nucleus, change into an electron and a positron. The sufficiency of total energy means enough total energy to produce the total energy of the two charged particles. Any excess energy becomes the total kinetic energy of the particles. This happens in nuclear experiments all the time. In a bubble-chamber photograph, in the vicinity of a magnetic field, this pair shows up as a pair of back-to-back spirals coming from the point where the charged particles were produced.

This reaction is evidently done by the electromagnetic force. The production of electron-positron pairs figures into quantum electrodynamic calculations. In this case, the two particles don't separate, but just turn right back into gamma ray photons again.