Electrons are fermions and cannot occupy the same quantum state, hence why there is exchange energy. Photons are bosons and are able to occupy the same quantum state, so there is no exchange energy for photons. Hope this answers your question :)
-another quantum chemist
D_jrivera t1_j8gzkvh wrote
Reply to comment by taphead739 in Light traveling through a medium that slows it. Does the same photon emerge? by TheGandPTurtle
Electrons are fermions and cannot occupy the same quantum state, hence why there is exchange energy. Photons are bosons and are able to occupy the same quantum state, so there is no exchange energy for photons. Hope this answers your question :) -another quantum chemist