Mkay. I see my confusion. You need something like a fluid and also in a non-inertial reference frame which is under some force of gravity or acceleration. I

Mkay. I see my confusion. You need something like a fluid and also in a non-inertial reference frame which is under some force of gravity or acceleration. I guess a supermassive black hole such as Sagittarius A (assuming it exists) could provide a force of gravity. Then you'd need enough dust or something to exert pressure on the objects around it. It seems likely there's not enough of anything remotely like a fluid dispersed throughout the galaxy to have such an effect though who knows? I'm clearly no physicist :).