cu-arpa.dietz@Cornell.ARPA (06/17/84)
My explanation of the Poynting-Robertson effect was slightly wrong. The emission of radiation from the particle does not change its momentum; rather, more starlight hits the front of the particle than the back due to abberation. A similar phenomenom limits the maximum energy cosmic ray particles can have. If they travel too fast they lose energy by scattering off 3 K background photons (blue shifted to gamma rays).