> And what does the equation:
> tau = (t + vx/c^2)/sqrt(1 - v^2/c^2) = (t - vx/c^2)/sqrt(1 - v^2/c^2)
> mean, if anything?
>
> Paul
>

v = 0, tau = t, xi =x of course.
tau1 = (t + vx/c^2)/sqrt(1 - v^2/c^2) alone doesn't imply v = 0, we have
tau1 > t.
It's called time contraction.

tau2 = (t - vx/c^2)/sqrt(1 - v^2/c^2) alone doesn't imply v = 0, we have
tau1 < t.
It's called good 'ole time dilation.
tau1 = tau2 DOES imply v = 0.