Why Pigeons at Rest Are at the Center of Complexity Theory

By January 2020, Papadimitriou had been thinking about the pigeonhole principle for 30 years. So he was surprised when a playful conversation with a frequent collaborator led them to a simple twist on the principle that they’d never considered: What if there are fewer pigeons than holes? In that case,Continue Reading

Scientists Are Mapping the Boundaries of What Is Knowable and Unknowable

Moore designed his pinball machine to complete the analogy to the Turing machine. The starting position of the pinball represents the data on the tape being fed into the Turing machine. Crucially (and unrealistically), the player must be able to adjust the ball’s starting location with infinite precision, meaning thatContinue Reading