Some questions you never think to ask. Others, you didn''t know you didn''t know. And some facts are so surprising they cry out for answers. What can a president actually do? Why do cities sink into the ground? Why is Australia seemingly invulnerable to recessions? Why do people in couples do more housework than singletons?The brilliant minds of the Economist collect these questions. Individually, they might seem bite-sized and inconsequential, but taken together they can reveal a whole new world.