synchrony

Synchrony is the coordination of events to occur at the same time or in a fixed phase relationship. It arises in natural and engineered systems and can refer to exact simultaneity or consistent temporal offsets. The phenomenon is studied across disciplines, from physics and biology to neuroscience and the social sciences.

In physical systems, synchrony occurs when coupled oscillators adjust their rhythms to move in step. Classic demonstrations include pendulums or metronomes on a common support. More formal models, such as the Kuramoto model, describe how a population of oscillators with different natural frequencies can synchronize under weak coupling, a process known as entrainment or phase locking.

In biology, circadian clocks synchronize with external cues like light–dark cycles. Cardiac tissue coordinates contractions through electrical coupling to maintain a heartbeat. In the brain, neural synchrony—coordinated firing across regions—supports perception, attention, and memory, while excessive synchrony is linked to disorders such as epilepsy.

In human and animal societies, synchrony manifests in collective behavior: groups clapping in rhythm, dancers moving in unison, or birds and fireflies flashing in concert. Social entrainment often emerges from local interactions and shared rhythms.

Measurements include cross-correlation, coherence, and phase-locking values to quantify alignment in time or phase. Synchrony can be complete or partial, stable or intermittent, and may involve a fixed phase difference rather than exact simultaneity.

Understanding synchrony helps explain coordinated activity across scales and informs applications in engineering, medicine, and the arts.