Curt Jaimungal has an interesting video on YouTube today. I'm prepared for the almost inevitable debunking but it looks promising. The correction she (Claudia de Rham) makes to general relativity is to give the graviton a very tiny mass of the order of 1e-33 eV rather than zero. The energy is so small that a galaxy cluster is within the quantum wavelength of a graviton. E = h c/wavelength The equation (E = \frac{hc}{\lambda}) is a relation between the energy of a photon (or, by analogy, a graviton) and its wavelength. If the graviton has a mass, it's Compton wavelength would be incredibly large, meaning that quantum effects of gravity could become noticeable only over vast distances, potentially comparable to the size of galaxy clusters or even larger structures in the universe. This kind of theory is still speculative and subject to significant scrutiny and testing. I think her theory only covers dark energy. Dark matter needs a much smaller scale. In this theory, gravity fades out faster than 1/d^2 (inverse-square law) at large distances and eventually has no effect. However on smaller scales, like within galaxies or solar systems, gravity would still behave according to the (1/d^2) law, meaning massive gravity wouldn't noticeably change our understanding of gravity in these contexts. There is something intriguing about this. Mathematical rigor is the hard part I guess.
Space's reaction to matter is the force. Matter is secondary, spacetime is primary. Three dimensional matter is relating to the fourth dimension spacetime, which is infinite.