In July, theoretical physicist Amos Ori of Technion, the Israel Institute of Technology in Haifa, proposed a provocative new model for a time machine. Unlike previous designs, Ori's version doesn't require exotic wormholes-theoretical tunnels from one point and time in the universe to another. Instead it involves a force, either man-made or natural, to warp a region of spacetime so drastically that lines of time form closed loops. Pilot a spaceship around this course, and you'll circle back to the past.