Quatum entanglement and FTL

On 21/10/2008, sailor.barsoom wrote:
> I don't entirely get the causality thing myself.
>
> If you live fifteen light years away from me, and I pic up the mike to
> my FTL radio and say "Hi," and you here that one year after I say it,
> where is the violation causality? Sure you heard it before a regular
> radio signal or laser carrying the same message would have gotten to
> you, but so what? It would only be a violation of causality if you
> heard it before I said it.
>
> OK, apparently I'm wrong about this, but I just don't get it.

No, that scenario isn't the problem.

The problem is that in relativity theory if there's significant
relative motion then the space-like interval (the space axis) of the
moving ship can cross over into your past- so then they get on their
phone and talk to you last year.

It's basically because the space and time axis in relativity tilt when
there's relative motion, and depending on some details of the FTL you
get big, big problems.

So if they're moving away from you fast enough, they can connect you
to yourself yesterday.

--
-Ian Woollard

We live in an imperfectly imperfect world. Life in a perfectly
imperfect world would be much better.