Surprising new work bucks 50 years of assumptions about the trade-offs between computation space and time Thomas FuchsOnce upon a time computers filled entire rooms, reading numbers from spinning tapes and churning them through wires to do chains of basic arithmetic. Today they slip into our pockets, performing in a tiny fraction of a second what used to take hours. But even as chips shrink and gain speed, theorists are flipping the question from how much computation space we can pack into a mac...