metastably

Metastability is the condition of a system that resides in a metastable state—a local, non-global minimum of an energy or free-energy landscape that is separated from the most stable state by an energy barrier. A metastable state is not the lowest-energy configuration, but it can persist for a long time because fluctuations or perturbations are unlikely to overcome the barrier. Metastability is distinguished from true stability in that the state is transient on the timescale of interest, and from instability, which drives the system away under small perturbations.

The lifetime of a metastable state depends on barrier height, temperature, and coupling to the environment; transitions can occur through thermal activation, quantum tunneling, or external forcing. In many contexts, metastable phenomena appear as long-lived phases, such as supersaturated solutions, supercooled liquids, or certain solid-state phases. In chemistry and materials science, metastable phases can persist until nucleation and growth of a more stable phase proceeds. In cosmology and particle physics, metastability is used to describe false vacuum states or configurations that are not the ultimate ground state.

In electronics and computing, metastability refers to a temporary condition in which a digital element (for example, a flip-flop) does not resolve quickly to a definite binary value, often due to input changes near a clock edge. This can violate timing guarantees and is mitigated with synchronizers and careful design. The adverb metastably describes actions or processes occurring within such a state, for example, a system decaying metastably toward a stable configuration.