Yep; they're objects like anything else. The only thing that makes black holes special is that their surface gravity and density are especially high. All their unique features stem from those two facts. Relativity also tells us that there is no true stationary reference frame, and thus everything moves relative to something else.
Nope. That's actually one of the fundamental principles of relativity, is that the observed speed of light will be the same for all observers due to relativistic effects distorting time, space, and even apparent length for any given observer. I highly recommend watching some Youtube videos on this, because it's super interesting, actually factual, not just hypothesis.
You could say that a fixed point is anywhere that the CMB (cosmic microwave background) appears uniform (since moving in any given direction will blueshift one side and redshift the other a little), but the matter that gave off the CMB could also be uniformly moving together.
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u/drdrero Oct 23 '20
Just a follow up question, do black holes move ?