The circumference of a rotating disc seems to contract, according to relativity. It is contracted because all points are in motion relative to a non-rotating observer, causing a length contracting between them. This means that measuring sticks being laid around the disc shrink which means additional sticks have to be laid on it. Or not? This problem is discussed in Ehrenfest's paradox.
How can this be resolved? Can we say that the circumference of the disc stays the same, but the flat spacetime it's in is transformed to a cone shape with its point in the center of the disc, so the circumference indeed decreases but the radius stays the same?
