While, I read that if a body accelerates to the speed of light would have an infinite mass and therefore, infinite energy would be required to maintain the speed.
A question popped up in my mind:
Assuming we've a body traveling at the speed of light (and having infinite mass), how difficult would it be to stop that body? What if it collides with a planet, would it stop or will it continue moving?
EDIT: Only infinite source (or tremendous source) of energy would be required to reach the speed of light. Once reached at that speed, I guess, nothing would try to stop it in a vacuum (except colliding or gravitational bending).