A good rule of thumb is Olga's prayer g y = c hartshorn ----- Original Message ----- From: "Dan'l Danehy-Oakes" <danldo at gmail.com> >>> with constant acceleration of 1 m/sec^2 it is needed about 50 years to >>> get >>> to relativistic speed, and the same to slow down. >> >> I think you are off by a factor of 5 or so.