^ Relativity. at all speeds the speed of light is always measured to be the same, all measures of time and space for the moving object distort so that measurements of the speed of light from their point of view, and that of some other observer moving at a different speed though space measure the speed of light as always the same.

This means that as a spaceship gets closer to the speed of light, the length of it in the direction of motion compresses relative to a stationary observer, and the time experienced by that spaceship slows down relative to that same observer. One can get as close to the speed of light, but any extra acceleration you apply to that spaceship will always come up short of the speed of light, you can never quite reach it, and for a person on the spaceship would would not appear to be anything close to the speed of light, as that speed will always be the same whether forwards backwards or sideways to the direction of motion.