1968/05/25 by Kenneth Nordtvedt · 396 citations
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Brans–Dicke theory #Classical mechanics #Cosmology and Gravitation Theories #Einstein #Equivalence principle (geometric) #Geometry #Gravitation #Gravitational acceleration #Gravitational field #Mathematical physics #Mathematics #Order (exchange) #Physics #Quantum mechanics #Relativity and Gravitational Theory #Scalar (mathematics) #Space (punctuation) #Space time #Spacetime #Theoretical physics
paper · doi:10.1103/physrev.169.1017
published in Physical Review 169(5), 1017-1025 (American Institute of Physics)
openalex publication_date 1968/05/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
The acceleration of a massive body in an external field for general space-time geometrical gravitational theories is obtained. The condition on the metric is such that \fracmgmi=1 is obtained, and we reobtain the result that \fracmgmi=1 in Einstein's theory for massive objects with time-independent internal structure. But it is shown that a measurement of \fracmgmi for astronomical bodies would measure space-time metric components which have not been measured in other gravitational experiments. In the scalar-tensor gravitational theory due to Brans and Dicke, it is shown that \fracmgmi differs from 1 by a term of the order of the massive body's gravitational self-energy divided by its total energy.