Is momentum related to gravity?

Momentum is the quantity of motion by a moving body, and gravity affects all things that are moving (I know there's probably some things but I'm generally speaking), so yes momentum is related to gravity in a sense. You can't gain infinite momentum without gravity playing it's part. read more

So rather than energy and momentum being related to each other as gravity is related to something else, both energy and momentum (as well as any nongravitational forces, also represented by the same tensor on the right-hand side; this is the "stress" part of that tensor) are related to gravity exactly the same way in the general theory. read more