2008/02/11 by Jacob D. Bekenstein, Eva Sagi · 3 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Solar and Space Plasma Dynamics #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.77.103512
published as Phys.Rev.D77:103512,2008 · 9 pages, RevTex
arxiv created 2008/02/11 · openalex publication_date 2008/05/14 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In the scalar-tensor gravitational theories Newton's constant GN evolves in the expanding universe. Likewise, it has been speculated that the acceleration scale \mathfraka0 in Milgrom's modified Newtonian dynamics is tied to the scale of the cosmos, and must thus evolve. With the advent of relativistic implementations of the modified dynamics, one can address the issue of variability of the two gravitational ``constants'' with some confidence. Using TeVeS, the tensor-vector-scalar gravitational theory, as an implementation of Milgrom's modified Newtonian dynamics, we calculate the dependence of GN and \mathfraka0 on the TeVeS parameters and the coeval cosmological value of its scalar field, \ensuremathφc. We find that GN, when expressed in atomic units, is strictly nonevolving, a result fully consistent with recent empirical limits on the variation of GN. By contrast, we find that \mathfraka0 depends on \ensuremathφc and may thus vary with cosmological epoch. However, for the brand of TeVeS which seems most promising, \mathfraka0 variation occurs on a time scale much longer than Hubble's, and should be imperceptible back to redshift unity or even beyond it. This is consistent with emergent data on the rotation curves of disk galaxies at significant redshifts.