# Re: starship-design: FTL idea

```Timothy van der Linden wrote:
>Isaac,
>>>That means it is moving at only 1.03053c in the frame where B moves with 0.9c
>>>-1.8=(0.9-1.03053)/(1+(0.9*-1.03053))

>>1.8=(.9-1.45)/(1+(.9*(-1.45)), whatever the significance of this
>>equation.  You have to be very careful about whether you're looking
>>at a beam sent in the same direction or opposite to the direction
>>ship B is moving in.

>According to your equation 1.8 and .9 are in the same direction? I thought
>ship B sent the beam in the opposite direction of the ship's movement.

Like I said, I don't know exactly what your equation is calculating.
You have a bunch of numbers but no generic equation.

One thing, though, is that the message is being sent backwards in
time, so the sign of its velocity is the opposite of what you'd
expect.  A message being sent backwards in time in the "south"
direction has a velocity in the "north" direction.

Like I said, the easiest way to see how a message is being sent back
in time is with space-time diagrams.
--
_____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
__|_)o(_|__
/___________\ "Mari-san...  Yokatta...
\=\)-----(/=/  ...Yokatta go-buji de..." - Karigari Hiroshi

```