[raganwald]

Time dilation:

http://en.wikipedia.org/wiki/Time_dilation

Ok, so let's take two twins, Raj and Ragan. Raj is orbiting a massive cosmological object, Ragan is on the surface. Ragan's time appears to travel slower than Raj's time.

Does FTL communication between Ragan and Raj ever create a situation where messages can travel backwards in time? Does bringing an observer into it help?

[martincmartin]

As you were posting this, I edited my post to fill in more details. You've got me re-reading my special relativity texts, which I haven't touched in 20 years, and for which I thank you. :)