# Time Travel Question (from A Briefer History of Time )

1. Feb 26, 2010

### Legendre

Time Travel Question (from "A Briefer History of Time")

I read the original "A Brief History of Time" and is now reading "A Briefer History of Time". :P

There is a part about time travel that confuses me. Does anyone want to enlighten me using layman terms? (i am a mathematics major, not a physics major >_<) It is on page 108-109 of the book "A Briefer History of Time" in the chapter "Wormholes and Time Travel" if anyone wants to refer to it.

The scenario described is this:

1) An event A happens on Earth. 1 hour Earth time after event A, event B happens on another planet (Proxima Centauri, PC) which is 4 light years away.

2) Someone on Earth during event A can only get to event B if he is capable of faster than light (FTL) travel since B is 4 light years away.

3) To an observer on PC moving away from Earth at nearly the speed of light, it would appear the order of the events is reversed: event B appears to occur before event A. This observer would say its possible, if you could travel FTL, to get from B to A.