Constraint on G˙/G from Orbital Timing

Abstract

Abstract Constraints on the variation of the gravitational constant G have been obtained by many observers using different methods, the most reliable and stringent being those based on the orbital timing of bodies in the solar system and binary pulsars. We show that the constraints determined from orbital timing are on G ˙ / G − 3 c ˙ / c rather than on G ˙ / G when the speed of light c is also considered to be varying. Increasingly tighter constraint on G ˙ / G from these observations are possibly due to G ˙ / G − 3 c ˙ / c = 0 . This relationship between G and c was determined in a previous work by fitting the supernovae 1a data using the relativistically covariant cosmological model with varying c , G and cosmological constant Λ.