The Gödel metric is said to describe a rotating universe, but I don’t really understand what is rotating there. It seems that the dust grains maintain constant positions and don’t actually move, yet an observer riding one of the dust grains sees all the other dust grains revolve around him. What is actually rotating, and what axis does it rotate around?
There are inertial frames co-moving with the dust where the dust appears static. However if such an observer where for example to throw a ball in the x-z plane, they would see it’s path curve and conclude they are in fact spinning on the y axis.
The Gōdel Coriolis Effect.
I thought the curves were from the Girdle* effect.
*Not random snark. See theorized saddleback shape of the universe