The principle of relativity applied to the expanding universe explains gravity and the galactic rotation anomaly

The belief that the energy density of space is constant is challenged. As an alternative, it is proposed that the energy density of space decreases as the universe expands but it must be observed as constant. If true, dimensional constants of nature must change, or transform, while dimensionless constants and the laws of physics remain constant. Transforms were determined that predict that both length and mass increase as the energy density of space (EDS) decreases. Specifically, Length ∝ 1/EDS, and Mass ∝ 1/(EDS)². It is suggested that this mass increase of matter is absorbed from space thus creating a flux of space energy toward all matter particles, which explains gravity. The rate of mass gain is calculated to give a flux of space momentum that will accelerate matter particles near another body of matter consistent with newton's law. The quantification of mass gain sets the rate of length expansion via the transforms. It is shown that this rate of length expansion, or acceleration, can quantitatively explain the rotation anomaly of galaxies as outward acceleration of galactic orbits and does not require dark matter to confine galactic stars to circular orbits.