The fastest speed at which we might commu-
nicate with another technological civilization
among the stars (according to our present un-
derstanding of science) is
1. the orbital speed of the Earth.
2. instantly (as fast as we want) if we only
knew where they were located.
3. the speed of light.
4. the speed of the Voyager spacecraft
(which is typical of our space probes).
5. the speed of sound (the natural speed for
messages).