Hi all, I was thinking about special relativity and spacetime and had the thought of measuring our velocity with respect to spacetime. I was wondering why this would't work and what makes it different from the ether, which we would be able to measure our velocity with repsect to to determine absolute motion. Especially when considering gravitational waves- if they pass through you when you are 'stationary' and when you are moving away from their source at a constant velocity, would you not be able to tell the difference? I actually had this thought when considering background independence for general relativity- how is it background independent if it relies on the warping of spacetime... although I'm sure that's a question for another thread! Sorry if this is a really stupid question, and thank you for any replies!