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One of the few experimental handles on unified theories of gravity with other interactions comes from possible time variation of coupling constants over the Hubble time: H₀^_^-1 (7. 67{10^-11 yr^-1) }^-1. We present a new theory-independent estimate (consistent with zero) of the time variation of Newton's gravitational constant derived from the timing of the binary pulsar PSR 1913+16: { { \. {}G}₀}{G₀}= (1. 02. 3) 10^-11 yr^-1. We anticipate that this estimate will become sharper as more data are acquired.
Damour et al. (Mon,) studied this question.