Beyond Extraordinary Claim: Gravitational Constant is Variable (& its a solution to the faint sun paradox!)

Can a variable gravitational constant resolve the Faint Young Sun Paradox ?

Authors:

Sahni et al

Abstract:

Solar models suggest that four billion years ago the young Sun was about 75% fainter than it is today, rendering Earth's oceans frozen and lifeless. However, there is ample geophysical evidence that Earth had a liquid ocean teeming with life 4 Gyr ago. Since L⊙∝G7M5⊙, the Sun's luminosity L⊙ is exceedingly sensitive to small changes in the gravitational constant G. We show that a percent-level increase in G in the past would have prevented Earth's oceans from freezing, resolving the faint young Sun paradox. Such small changes in G are consistent with observational bounds on ΔG/G. Since LSNIa∝G−3/2, an increase in G leads to fainter supernovae, creating tension between standard candle and standard ruler probes of dark energy. Precisely such a tension has recently been reported by the Planck team.