[ see also 5U7Dk.112564$Pi5.13985@newsfe18.ams2 ]

> Shouldn't you first try to find (without calculus, like you claim
> you can) the derivative dtau/dt of a simple function like
>      tau(t) = c/a arcsinh(a t/c)
> and then try to express v(t) as a function of t and a from
>      dtau/dt = sqrt(1-v^2/c^2)
> ?
> Dirk Vdm

1. There IS no acceleration in dtau/dt = sqrt(1-v^2/c^2)!
2. The velociy v is NOT a function of t.
3. The equation
        tau(t) = c/a arcsinh(a t/c)
is therefore UNRELATED to
        dtau/dt = sqrt(1-v^2/c^2).

Let v = .8c and try it yourself, Dirk.

glird