I have always been fascinated by time travel, parallel universes and ofcourse UFOs. I read somewhere that in order to get from one universe to another or for time travel one had to traverse through a Mobius Circle - a cirle with a little twist in it.

From Wiki:

A Möbius strip made with a piece of paper and tape. If an ant were to crawl along the length of this strip, it would return to its starting point having traversed every part of the strip without ever crossing an edge.