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Volume 16: Pages 86-100, 2003

On Criticisms of Einstein's Equivalence Principle

C. Y. Lo

Applied and Pure Research Institute, 17 Newcastle Drive, Nashua, New Hampshire 03060 U.S.A.

Einstein's equivalence principle was initially the equivalence of an accelerated frame and uniform gravity. In spite of being often challenged, Einstein insisted on the fundamental importance of his equivalence principle to general relativity. It is shown that existing criticisms, starting from Synge and Fock, are due to misunderstandings and misconceptions in physics and/or inconsistent considerations. These include the misinterpretations of Pauli, Bergmann, Tolman, Landau and Litshitz, Zel'dovich and Novikov, Dirac, Wheeler, Thorne, Hawking, and others. It has been overlooked that Einstein's equivalence principle implies uniqueness of the gauge for a given frame of reference. The recent criticism by Hong has the distinction of starting from his intuitive, though inadequate, observation that “a homogeneous field is characterized by the fact that any part of it is representative of the whole.” It is pointed out that his notion of uniform gravity disagrees with experiment on the gravitational redshift. His arguments concerning acceleration also disagree with special relativity, while repeating the same mistake of Landau and Lifshitz. Moreover, it is pointed out that the crucial role of Einstein's equivalence principle in general relativity is firmly established because the Maxwell‐Newton approximation, which is rigorously derived in the theoretical framework of general relativity, is unambiguously supported by experiments. Thus the Schwarzschild solution is actually invalid in physics.

Keywords: Einstein's equivalence principle, frame of reference, Euclidean‐like structure, physical space‐time

Received: August 20, 2002; Published online: December 15, 2008