How are the Olympics swimming races timed?

As you may have already heard, M. Phelps just won his 7th gold medal by .01 second. We all know he is a BAD-@$$. The question here is how are those races timed? There must be some really awesome equipment at work to be able to tell if a dude wins by .01 of a second! LAZERS?!?! (NO!!!!) Is the end of the pool (where they touch) sensitive to touch and stops the clock right when they touch it?!?! (Seems the most likely) By the way, whoever knows the answer to this question is a "effing"STALLION! Thanks