I understand that cosmic rays can (and do) propagate through space extremely rapidly. But just how rapid, I wonder? (For reasons I know not, and despite having googled questions like "Speed of cosmic rays" and "How fast do cosmic rays travel?", I keep drawing a blank. I gather that subatomic energies and their measurements - like 'Gev' etc - are fundamental to the nature of cosmic rays; but I'd still like to know how fast the little blighters go. . . that is in km/s, for e.g.) Even an educated guess would be helpful. Thanks in advance.