- #1

wukunlin

Gold Member

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## Main Question or Discussion Point

from what I know: cross section in particles physics can be seen as throwing random darts on ballons on a wall, ie the wall is stationary.

but if I want to work out the cross section of two laser beams at certain angles, the analogy above wouldn't hold would it? Since photons can never to stationary.

So in the case of photon-photon scattering, what sort of approach would be required to find the cross section?

but if I want to work out the cross section of two laser beams at certain angles, the analogy above wouldn't hold would it? Since photons can never to stationary.

So in the case of photon-photon scattering, what sort of approach would be required to find the cross section?