Forum:What are the Zones?

There is a question that has lingered in my mind for sometime concerning the Sonic universe but I could never find the answer to my inquiry. Just what exactly are the levels in the Sonic games known as the Zones supposed to be? Are they separate dimensions, areas of space or what? Granted, I am not at all well versed in physic, quantum physics, rocket science and I know only high school level astronomy but I want to know what exactly are these Zones in the Sonic Universe are.