Is there an abstract reality called gravity over and above the warp and woof of matter? General relativity says No. Nore is there anything like absolute space or time over and above the convolutions of matter in motion.
Matter in motion? Presumably, energy is what moves material components throughout the universe. But I wonder: Is energy a substantial reality over and above particles in motion? If not, what is motion is not energy? Does energy produce motion or does motion produce energy?
If at some point long, long ago nothing was in motion-- principally because there was no determinate thing to move-- what set eveything in motion? If the primal state of nature is pure potential energy in a quantum froth, what could have released that energy into motion? Further, if all matter was contracted into dimensionless density, what object could act upon (i.e., move) any other object to produce energy?
Just some questions I've had after reading a little book on thermodynamics, inter alia.