''Nerd royalty'' Ben Goldacre ''Laugh-out-loud funny'' Bill Gates''Totally brilliant'' Tim HarfordWHAT IF you still had so many more strange questions about the universe?And WHAT IF Randall Munroe, former NASA roboticist and xkcd creator, were prepared to move mountains, fill the solar system with soup and alter the space-time continuum to answer them?Whether it''s how to make a lava lamp out of lava or feeding the inhabitants of New York to a T. Rex, welcome to the weird, wonderful (and sometimes terrifying) world of WHAT IF? 2