Dark energy is a smooth component with sufficiently negative pressure to drive accelerated cosmic expansion.
Dynamical dark energy has an energy density or equation-of-state parameter that changes with cosmic time, unlike a cosmological constant.
Articles by others on the same topic
Dark energy is a mysterious form of energy that is thought to permeate all of space and is responsible for the accelerated expansion of the universe. It was first identified in the late 1990s when observations of distant supernovae showed that the universe was not only expanding but that its expansion was also accelerating.