XKCD Presents “What If?”

If there was a robot apocalypse, how long would humanity last? What would happen if you tried to hit a baseball traveling at 90% the speed of light?

If you are at all into “romance, sarcasm, math, and language,” you have no doubt heard of XKCD comics. If you are like me, you have snickered at nerdy jokes and puzzled over concepts while claiming to friends, “Of course I get it!” before excusing yourself to secretly Google the science that makes it funny.

Now the creator of XKCD has written a boo...