“and the latter [G C Wick] showed that cosmic ray primaries should consist mainly of protons because energetic electrons would undergo too much scattering from photons in intergalactic space (through the inverse Compton effect) to reach the vicinity of the Earth.”

Sean recently mentioned here that physicists considered it unlikely that black holes would have a net charge. But if electrons are scattered more than protons, might there not be more protons reaching the hole and falling into the event horizon? (Unless there are equal numbers of antiprotons of course)