Our center of mass remains approximately in a constant inertial reference frame (our accelerations combined with our meaningful time scales are negligible compared to c). However, at the atomic and sub-atomic scale, particles jiggle and oscillate at what I understand to sometimes be relativistically non-negligible speeds and accelerations, sometimes having relative velocities among each other a non-negligible fraction of c.
My main question is: is there a formal or intuitive way to understand how all this nanoscopic reference frame switching sort of "averages out" all weird time dilation, length contraction, non-simultaneity, etc. effects to give rise to the effectively uniform inertial reference frame experienced by that macroscopic object?
Second question: does this mean that our subjectively perceived proper time is significantly different from the proper time experienced by the individual particles that make us up? Would this have any important effect if any of those particles had comparably short lifetimes? What is the relation between the proper time of the center of mass of an ensemble of high energy particles vs. the proper time of any given particle in the ensemble?
