What does dark energy mean?
Dark energy is the name for an unknown component used in cosmological models to explain accelerating expansion.
Formation, motion and physical explanation
Distant supernovae, the cosmic microwave background and large-scale structure constrain expansion history. The simplest model is a cosmological constant.
Evidence, applications and limits
It is not dark matter: matter clusters, while dark energy appears smoother. The name does not mean the mechanism is understood. Conclusions about distant objects rely on testing images, spectra, time variation and physical models together.
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