The twenty-fourth Carnival of Mathematics is online at Ars Mathematica. To Ars, 24 is a special number because the Leech lattice lives in 24 dimensions (and, really, what could be creepier than a lattice of leeches? — methinks that could be the title for the sequel to The Halting Oracle). It’s also interesting to the secretive, cultish cabal of quantum gravity research, since it’s 26 (the critical dimension for bosonic string theory) minus 2 (the dimensionality of the string world-sheet). These two occurrences are actually related, although there’s a reason the relationship falls in a domain called Moonshine theory. . . .