Newton’s Law introduced an idea that many top intellectuals of the day could not accept:
The concept of action-at-a-distance.
How could 2 objects located half a Universe away, suddenly and instantaneouly exert a force on one another?
How could they interact from so far away without anything intervening to mediate it?
Descartes couldn’t accept it, and instead formulated an alternative where there was a medium that Gravity travelled through.
Space is filled with a type of matter, he argued, and that as a mass moved through it, it displace that matter and created vortices: an early version of the aether.
This was the earliest in a long line of what would be called mechanical (kinetic) theories of gravity.
Descartes’ conception, of course, was wrong.
Agreement with experiment is what determines the utility of a physical theory, not our predispositions towards certain aesthetic criteria.
When General Relativity came along, it changed the picture Newton’s Laws had painted for us in some fundamental ways.
For example, Space and Time were not absolute and the same everywhere, but were related and behaved differently for observers moving at different speeds and at different locations.
Is Gravity instantaneous?
How fast does it travel?