Webcomic xkcd regularly revolves around jokes that require a degree in math or physics to appreciate--which makes sense, because author Randall Munroe has an undergraduate degree in physics. He recently started up a weekly blog called What If? that answers reader questions by putting his past career as a physicist to use. And the first one is awesome: "What would happen if you tried to hit a baseball pitched at 90% the speed of light?"
As Munroe explains, things wouldn't go well for the batter. Or the pitcher. Or anyone within a square mile, really.
At 90 percent the speed of light, or 604,000,000 miles per hour, the ball would be traveling so much faster than the air particles around it that it would collide with the particles in front of it. That collision would release gamma rays and tear apart air molocules, creating an expanding bubble of plasma that arrives at the plate before the ball itself.
Well, the ball doesn't even get there at all, really: in the 70 nanoseconds it takes to arrive, it's turned into a cloud of debris. That's about the time the batter is swept backwards into the backstop and disintegrates, even though he hasn't even seen the pitcher release the ball yet. Within a microsecond everything else disintegrates, too.
The whole thing's more fun with Munroe's illustrations, so check out the original post. Still, the lesson's pretty clear: steer clear of lightspeed baseballs.