Light Dragging, the Origin of Hubble's Constant
  Recently E. Harrison has argued the Red Shift distance law proposed by Hubble and velocity-distance law developed later on theoretical grounds has no general proof demonstrating the two laws are actually equivalent. It is the purpose of this paper to account for the nebular redshift law of Hubble based on two principles: 1) Spacetime motion and light dragging. 2) An overall spacetime index of refraction based on Hubble's Constant. 
Walter J. Christensen Jr