Things like this are only impossible until someone figures out how to do it.
In an Alcubeirre warp-drive, your ship is subjectively sub-light. Warping the space-time around the ship causes the apparent movement. Space-time being essentially mass-less, the Einsteinian “speed of light in a vacuum” doesn’t come into play.
Fallacious reasoning shared by some others on this thread. Some things are simply impossible given the nature of the universe. Finding "unknown elements" somewhere out in space is impossible. Violating either the first or second laws of thermodynamics is impossible. Exceeding the speed of light is impossible.