Have you ever thought up a question so completely off-the-wall, so seemingly ridiculous, that you couldn't even find the courage to ask it? Maybe at the sports bar you were transported by the beauty of your beer to wonder, "How long could I live on beer alone?" Or cycling through the park, you mused, "Did nature invent any wheels?" Or looking up at the night sky, you had a moment of angst: "What would happen if the moon suddenly disappeared—if it were vaporized or stolen by aliens?