KenGee,
The reference is supplied by GeoffW1. It is Electro Magnetic Radiation Push (EMRP) that causes gravity rather than Newton's pull gravity between two bodies. It varies and has a few interesting aspects for astronomers according to the author and even makes spacetime understandable. The speed of light varies as it bends in traversing a gravitational field, so perhaps there is an understandable explanation, so long as you ignore the maths as I have to.
Thank You!! GeoffW1
Ernie.