Objectivity Between Perspectives
Objectivity Between Perspectives On Lorentz, measurement, and what objectivity means Two physicists describe the same set of events, one of them aboard a craft moving rapidly relative to the other. They disagree about nearly everything one would first want to call a fact. They measure different lengths for the same rod, different times between the same two events, and if those events are spacelike separated they may even disagree about which came first. Yet they do not disagree about the physics. Translate one physicist's measurements into the other's by the Lorentz transformation and everything falls into place, and certain quantities turn out to be the same for both: the speed of light, and the spacetime interval that separates two events. What set their descriptions apart was perspective-dependent. What they shared was whatever survived the passage between their perspectives. This small example carries, to my mind, a large idea, and the whole framework I work with rests...