> Although what you say about significant digits is correct,
> we are speaking theoretically and can say, for
> the sake of argument, that we know our figure of
> 80 years to be exact up to whatever decimal place
> we wish. The same can be true for the 0.1c figure.
> So your answer, that the ship would be
> behind by six months, is valid in the theoretical sense.

Something of a non-sequitur, but, with all your text on the left side, it almost gives the illusion that you're writing poetry. Just thought you might want to know. :-}

dkd1