The speed of light is the maximum speed because photons have no mass so they cannot accelerate more than that, how can something that has no mass be atracted by a black hole (gravity)
Basically look at the gravity of the universe as a bed sheet stretch out..
When you put something with weight on the sheet you'll see it brings the surrounding area around it sinks..
this very same principal is how gravity works.. granted its a 3 dimensional plane.