What is the fastest a space ship can go?

there is no real world relationship between time and speed and m, all the theories depend on games in pure math where time = t and can be made to do all kinds of things, juggling numbers in meaningless equations is a favorite game of mathematicians just because in a random equation you can make m grow when v = velocity increases does not mean it has any relation to the real world for instance there are no negative numbers in the real world