time travel.

[altezon]

yeah i agree but you're on about actual traveling.

i'm on about slipping through the fabric of time itself. imagine a million earths, a billion billion billion billion earths all occupying the same space, all travelly at the same velocity all of an equal mass. now stick a pin into the earth. it will always be the exact same spot every time. we wouldn't be traveling in a linear line through time but stepping sideways. onto an exact same earth that's in a different time frame.

OK, but the earth isn't stationary. So the earth a month in the future is doing something different, because it's in a different place. In other words, if you want to visit the earth in a different time, you have to go to where the earth will be at that time. Let's say you're in London, January 2010, in the dead of winter, and you want to jump ahead to London, July 2010. At the new time coordinates, the earth will be at the other extreme of its orbit with the northern hemisphere tilted toward the sun instead of the southern hemisphere. It's inescapable.

Let's try a different example. A train shuttles back and forth between Washington DC and New York on a regular schedule, so that it's always leaving DC at 8am and arriving in New York at 2pm. You're in DC at 8am while the train is there and want to time travel 4 hours into the future, same location. When you debark from your time travel device at noon, the train will no longer be there. If you're on the train when you do your time travel, when you debark at noon you'll no longer be in DC.