RainmanTime
Super Moderator
http://www.foxnews.com/story/0,2933,345234,00.html
Looks like HDRkid and his RV gadget lie in category 3!
RMT
Category 1, as he dubs it, includes things that may become true within the next century, if not the next few decades: teleportation (already possible, but only among subatomic particles); telepathy (thanks to brain implants); invisibility (already being researched using light-bending 'metamaterials'); laser guns (existing, but hugely power-hungry); force fields; and the discovery of extraterrestrial life.
Category 2 includes things that are theoretically possible but would be realized only with thousands more years of technological progress: time travel (possibly through "wormholes" in space); traveling faster than light; and the discovery of parallel universes.
Category 3 consists of things that really are impossible because they violate the laws of physics. Only two concepts qualify: knowing the future and perpetual motion.
Looks like HDRkid and his RV gadget lie in category 3!
RMT