1 st Doha International Astronomy Conference, Feb 2013 Complying with Tully–Fisher Y Sobouti Institute for Advanced Studies in Basic Sciences – Zanjan (IASBS), Iran,

Tully-Fisher relation, an empirical rule, states: a. Rotation curves of spiral galaxies have flat asymptotes. b. Asymptotic speeds are proportional to the fourth root of the mass of the galaxy. Both features are utterly non Newtonian and non Einsteinian. They indicate insufficient gravitational force of the observed mass to keep stars in galactic orbit.

The followings from Sanders and McGaugh show the observed flat asymptote and the insufficient contributions from baryonic matter.

To explain observations: Since Zwicky, 1933, many scientists have turned to dark matters. Since Milgrom, 1983, many others have proposed modified and alternative gravities. To this date, however, neither any dark matter scenario nor any alternative gravity has found wide enough acceptance to call it consensus.

To Author's knowledge, however, one possibility is not tapped to date: To entertain time varying spacetime metrics around galaxies, and to pump energy to an outlying star from the gravitational radiation of the galaxy or from the radiation of any other field, such as Brans-Dicke scalar or others.

Conclusion: This is not finished piece of work. It is simply an idea among many.