Einstein said that gravity is an acceleration like any other acceleration. But gravity causes relativistic effects at non-relativistic speeds; so gravity could have relativistic origins. And since the strong force is thought to cause most of mass, and mass is proportional to gravity; the strong force is therefore also proportional to gravity. The strong force could thus cause relativistic increases of mass through the creation of virtual gluons; along with a comparable contraction of space around nucleons; and then be diluted by the relatively large volume of atoms. The strong force would thus indirectly cause the spatial contraction known as gravity. And since gravity would thus not be a true force, and there would then be no gravitons. And the electro- weak and strong forces would therefore be the only two forces of nature. A unifying equation was developed: E=(Ml+Mh/D)C^2; where E = the electroweak and strong forces; Ml = lepton masses; Mh = hadron masses; and D = (1-V^2/C^2), as a spatial contraction equaling 75.3982 fold. Einstein's formulas for excess radius Re = GM/3C^2, and for gravity Gab = 8 G/C^2 Tab; both relate mass to space curvature, and differ by 3x8 = 75.3982. And the same difference is found between the observed proton mass, and the experimentally determined mass of a proton's quark masses, at 12.5 MeV. So a revision of Einstein's equation for gravity is Gab = GD/3C^2 Tab, where 8 = D/3 reveals the relativistic origins of both 8 and of gravity. The early universe containing only energy, would therefore have contained no matter; and so, would have contained little gravity. And the inflationary period in the early universe would thus have been due the lack of gravity before matter had formed.