Every meaningful decision you make in conditions of uncertainty involves the same fundamental problem: distinguishing a real signal from background noise. The doctor examining an X-ray must decide whether a faint shadow is a tumor or an artifact of the imaging process. The security screener must decide whether the shape in a bag is a weapon or an innocent object. The investor must decide whether a market pattern reflects genuine opportunity or random fluctuation. The therapist must decide whether a patient’s reported symptoms indicate a clinical condition or normal variation in human experience. In each case, the underlying structure of...