@S1-A.ARPA,@MIT-MC.ARPA:DT50@CMU-CS-A.ARPA (06/30/85)
From: Dave.Touretzky@CMU-CS-A From the June 22nd issue of Science News, page 389: "Ernst Mach, who was both a theoretical physicist and a philosopher of science, worked out what became known as Mach's Principle. As Mach was a philosopher, different commentators differ as to what it was he actually said, but in the most general sense Mach's Principle proposes that the mass of any body is related to the masses of all the other bodies in the universe. This means that if the geometrical relationship between a given body and the rest of the universe changes, the mass of the given body will change." The article goes on to explain how Mach's Principle appears to violate Einstein's theory of relativity. A recent test conducted by NBS (the latest in a long string of tests of Einstein's theory) produced results consistent with relativity theory; no mass change was detected. However, some scientists apparently feel that Einstein didn't disregard Mach's Principle; rather, he interpreted it in a way which causes it to cancel itself out. Thus, the universe could still exhibit Local Lorentz Invariance (as predicted by relativity) without contradicting Mach.