Mach's principle [SEP] named after
Mach's principle
In theoretical physics, particularly in discussions of , Mach's principle (or Mach's conjecture) is the name given by Einstein to an imprecise hypothesis often credited to the physicist and philosopher Ernst Mach. The idea is that the existence of absolute rotation (the distinction of local inertial frames vs. rotating reference frames) is determined by the large-scale distribution of matter, as exemplified by this anecdote:
You are standing in a field looking at the stars. Your arms are resting freely at your side
originating a long-lasting debate.
Most physicists believe Mach's principle was never developed into a quantitative physical theory that would explain a mechanism by which the stars can have such an effect. It was never made clear by Mach himself exactly what his principle was. Although Einstein was intrigued and inspired by Mach's principle, Einstein's formulation of the principle is not a fundamental assumption of general relativity.
Mach's principle in general relativity.
Because intuitive notions of distance and time no longer apply, what exactly is