The boundary between the quantum and classical worlds has long puzzled physicists. In a recent Quanta Magazine article, physicist Jonathan Halliwell argues that decoherence is the key to understanding how the wave-like behavior of matter and energy gives way to the familiar macroscopic world.
Decoherence occurs when a quantum system interacts with its environment, causing superpositions to lose their quantum character. This makes larger objects appear classical, though the process is gradual rather than a single event. Halliwell's account suggests there is no fixed point where quantum ends and classical begins; instead, the transition depends on how strongly a system is coupled to its surroundings.
Because the article presents one researcher's explanation, it does not offer competing views. But it does clarify a central idea: the classical world we experience may emerge not from a mysterious collapse, but from the everyday process of being observed and interacting with the environment.