Guess what? There appears to have been an asymmetry in the behavior of neutral B-mesons during a collision at Fermilab's Tevatron accelerator! Not excited? Try this: If there hadn't been, you probably wouldn't exist. Conventional particle physics dictates that equal amounts of matter and antimatter should have been created during the Big Bang, but that's impossible, since matter and antimatter mutually annihilate. The only way anything could be left over to start a universe would be if the scales had been tipped slightly in favor of matter, a sensible theory, but one that had never been glimpsed in action — until this year. In particle collisions at Fermilab, scientists discovered that the number of muons (a kind of heavy electron) created exceeded anti-muons by about 1%. That's not much, but long ago it was apparently just enough to kick start the cosmos. On such margins are universes made.