I really need an expert for these two: 1. How can we correct the clock of a satellite due to time dilation effect due to its motion relative to the ground when ground-based clocks can be equally considered in need of correction due to their motion relative to the satellite? Both equally valid relative views, according to special relativity, would mean there would be no singular, absolute time dilation to correct, and indeed, the need for correction should entirely cancel out, requiring no action whatsoever. 2. Since everything is relative in special relativity, it is equally valid to consider the Earth to be accelerating toward stationary particles in the upper atmosphere. In that case, time slows down for Earthbound observers. The particles then decay at their usual half-life pace in their stationary reference frame while only a fraction of these half-time passes for the speeding observers on Earth. Then, just as the speeding astronaut in the Twin Paradox returns to find a much older twin, the speeding Earthbound observers would encounter an extremely old population of cosmic ray particles, which means that they should have long since decayed, and should not have been detected.