Tuesday, May 1, 2007

The Physical Possibilities of Time Travel


So, Nick gave me a book that he read a couple years ago. It's called "The Physical Possibilities of Time Travel" subtitled "The Pysical Possibilities of Travel Through Time" by a physicist named J. Richard Gott. He talks about different mechanisms for traveling through space-time faster than a beam of light. Pretty interesting stuff, although most of it is fairly impractical now...like constructing a giant dense sphere around you with the mass of multiple suns.

Here were some statements (all consistent with Einstein's theory of relativity) in the book that blew my mind:
First, as illustrated above, the universe could have created itself through time travel. The loop on the bottom represents the infinite/recurring beginning. The black cones are all different universes going through the inflation stage.
Next, by weird properties of space-time and not-so-weird properties of light, "if you went on a long enough journey at a velocity near to but lower than the speed of light, you could actually return home at the time you started or even before" (p.92).
It explained weird geometries of space-time...one was compared to a room where when you walk out the front of the room, you immediately enter the back of the room...or when you go out the left side, you reappear on the far right side (like in some older video games)...likewise, go out the top and you're re-entered on the bottom. It's easy enough to think of this situation as a bunch of identical cubes stacked in a lattice, but it's hard to imagine for only one universe.
It also talks about how 2 different observers can have different perceptions of an event and both be correct about their observations.

In short, I recommend it...quick read...I finished in 2 days.
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