The Dark Side of the Universe

Professor Silk discusses how our understanding of cosmology has evolved in recent years from the old Big Bang cosmology of the Einstein era. Observations have shown us that the universe is mostly dark. This is one of the greatest mysteries in the cosmos. Not only is the observed night sky dark, but also most of the matter in the universe is dark. Astronomers today are seeking to unravel the nature of the mysterious but pervasive dark matter and dark energy, which account for two-thirds of the mass-energy density of the universe.