Terms: I know that there is supposed to be a difference between the two terms gravity and gravitation with the first referring to the earth's gravitational attraction and the second to the phenomenon in general, but here I am using both terms to refer to the phenomenon as such. Spin is generally used to describe the twisting motion inherent in particles, while rotation refers to an accumulation, a mass of particles, for instance a planet, rotating as a whole.

Gravitation, as observed and modeled by mainstream physics, seems to be insufficient to explain the continued existence of galaxies as unitary systems. There just doesn't deem to be enough mass in all those numerous stars to be able to hold them galaxies together by gravitational pull alone. Mainstream scientists resort to such nebulous concepts as "dark matter" to explain there might be a great deal of mass we just can't detect. I do not think that is a good way to approach the problem.

To make any headway in this, we actually need to conceptualise the cause of gravity, something which physicists have been quite reluctant to do ever since the times of Newton, who described gravity, but when asked what the cause was, he recused himself with the words ("hypotheses non fingo") or "I'm not proposing a hypothetical mechanism." We are associating gravity with mass, but we have no conceptual understanding why masses "gravitate" towards each other. There are theories all right, and there is much discussion, but we have no agreed way of modeling the cause of gravity....

Full article: http://blog.hasslberger.com/2015/04/spin_rotation_gravity_magnetism_star_formation.html