is the observation that all observable galaxies tend to have their spectra shifted into longer wavelengths, and this shift grows at an increased rate with time, indicating that galaxies are undergoing accellerated expansion away from one another. Word Bank:
Closed UniverseBig BangBig CrunchBig RipCosmic RedshiftDark MatterDark EnergyCosmic Microwave Background RadiationUniverseOpen UniverseBig FreezeFlat Universe