Because of General relativity. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations.I see later applicants progress though. I wonder why the backlog affects people differently
it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape. Hence things progress differently.