Here's a question: What would happen if you tried to hit a baseball pitched at 90 percent of the speed of light?
The answer is: Don't.
Not that anyone's going to pitch a ball that fast, but if they do, you definitely don't want to be the batter. Or the pitcher. Or in the stands watching. Or anywhere near the ball field. But, trust me, you very definitely want to see what happens.
Cartoonist Randall Munroe over at xkcd has just launched an every Tuesday "what if?" series. And in this first one, he's asked what would happen if a ball approached 90 percent of the speed of light. His answer, mixed with his wonderfully primitive illustrations, starts calmly...
To see what follows, go over to his place, but first, put on some sunglasses, buy a lead suit, then click here.