Similar physics mystery: You're a pool of water in the bottom of a bucket, looking out at the stars. Somebody spins the bucket, making the stars spin. So you (the water) arrange your molecules in a parabolic shape, thicker at the sides of the bucket and thin in the middle.
How do you (the water know)? How do you know that the stars aren't holes in a paper sheet with light shining through? How do you know the universe isn't spinning, and you're standing still?
How do you (the water know)? How do you know that the stars aren't holes in a paper sheet with light shining through? How do you know the universe isn't spinning, and you're standing still?