That is actually false from the frame of the traveler. Using constant acceleration, the traveler will observe constant energy usage. Then length contraction wil

That is actually false from the frame of the traveler. Using constant acceleration, the traveler will observe constant energy usage. Then length contraction will guarantee that you can reach speeds arbitrarily close to speed of light( and also any location in the universe ) in about ~50 years with 1G acceleration. http://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration#A_Half_Myth:_It_gets_harder_to_push_a_ship_faster_as_it_gets_closer_to_the_speed_of_light http://en.wikipedia.org/wiki/Space_travel_using_constant_acc...