Think of the infinite cycle back and forward in time as a clock on the wall. Midnight is the big bang, and the hand on the clock goes around and around going through the stages of the universe until it reaches the big bang again. Even if you push the hand on the clock backwards theres no end.

As for multiple universes or dimensions, I like to think of it like a radio. You can tune a radio to different stations, and maybe our universe is like a radio station. That could probally explain alot about people seeing ghost, or that weird feeling you get like someones watching you and the hairs stand up on your neck but no ones there. Two radio stations bleeding into each other causing interference.