Well, accelerating a 100 ton spaceship to 0.99c (assuming some sort of beamed propulsion) requires only 2000 Terawattyears [1]. Of course, to turn 1e6 years in

Well, accelerating a 100 ton spaceship to 0.99c (assuming some sort of beamed propulsion) requires only 2000 Terawattyears [1]. Of course, to turn 1e6 years into 1 year relative time, one needs like 0.99999999c, one needs 2 million Terawatt years [2], which is a much bigger energy investment, but still not on the order of annihilating the planet. Breaking is gonna be a bitch tho. [1] 100000 kg * (0.99 * c)^2 / sqrt(1-.99^2) in Terawatt Years [2] 100000 kg * ( 0.99999999 * c)^2 / sqrt(1-0.99999999^2) in Terawatt Years