Here is a challenge to Draftscience's (Gary Mosher's) hypothesis presented by a respondent who claims to be a science journalist. Links to Gary's response will be presented below. Enjoy.
https://www.youtube.com/watch?v=7vfnFNC8TTY&t=116s
John Adams
Reasons why Push Gravity does not work
1. The gravity particles are thought of as classical particles with classical interactions. This notion is inconsistent with current understanding of particle physics – there is no particle which could have all the characteristics required by PG without violating one or more physical laws
2. The particle flux filling all space must be perfectly isotropic and of very high density. No known form of radiation of particle flux has these characteristics to the degree required by the theory
3. The neutrino. Modern proponents of PG often posit the neutrino as the mediating particle of the theory. This has been conclusively disproved by Richard Feynman (Feynman Lectures On Gravitation, 1995)
4. Transparency of matter. With increasing mass the change in gravitational shielding becomes mathematically less then the sum of the shieldings of the two bodies. To overcome this one has to place an extremely high lower bound on the flux density of these particles. This is inconsistent with experiments conducted to detect such flux energies.
5. Drag. Any mechanical model of PG necessarily creates a drag force, or else there would be no interaction between the particles and a massive body. In order to reduce the amount of drag to levels consistent with observation, the speed at which these particles move must be in the region of 10^17 m/s, which is many orders of magnitude higher than the speed of light.
6. Heat energy. If the particles of PG really move at superluminal speeds, which is in violation of basic physical principles, they would impart a heat energy onto any massive body sufficiently high to instantly incinerate any form of normal matter.
7. Aberration. In any mechanical model of gravity, the gravitational force can only act with finite speed, creating an aberration effect. Such an effect has not been observed.
8. Sources of gravity. As we know today, and as is experimentally well verified, all forms of energy are a source of the gravitational field, not just mass. This is not explainable by PG.
9. Time dilation. PG has no consistent mechanism to explain the well verified phenomenon of time dilation.
10. Deflection of light. PG cannot explain deflection of light rays while at the same time avoiding aforementioned problems with drag.
11. Thermodynamics. The flux of particles in PG would be many orders of magnitude more energetic then mass at rest. However, no transmission of energy is observed, even though there must be a form of interaction with ordinary matter. This leads to a violation of the laws of thermodynamics.
12. Perpetual motion. Due to shielding effects the existence of PG would make it possible to construct a perpetual motion machine. Again, this is in violation of the laws of thermodynamics.
13. Binding energy. Binding energy of elementary particles contributes to their gravitational energy, which is not explainable by PG.
14. Origin. There is no consistent explanation as to where those particles come from, why their flux never varies, why the field is perfectly isotropic, or why the total energy never decreases even if the universe is expanding.
15. Mathematics. The mathematics of PG are not self-consistent, and do not produce the correct results.
16. Frame of reference. PG would create an absolute frame of reference, which means that the Theory of Relativity must be false. This is in contradiction to experiment and observation.
17. Large scale structure. Due to the necessary isotropy of the PG medium, over very large distances the net forces would cancel out. This does not explain the large scale structure of the universe.
18. Non-existence. No flux field or particle stream as needed by PG has ever been observed by experiment or observation.
[1] re: John Adams comments on particle gravity
https://www.youtube.com/watch?v=GN_WNTXuK9A&t=1676s
[2] re: John Adams comments on particle gravity
https://www.youtube.com/watch?v=mjytyg-KJq4&t=265s