Dark Matter, Dark Energy - The Dark Side of the Universe

Fundamental Building Blocks (1x1)

Air date: Jan 01, 2007

Scientists now have a complete inventory of the universe, which is composed of three basic constituents: Ordinary matter includes every kind of particle ever directly observed; dark matter consists of massive particles known only because of their gravitational effects; and dark energy is a smoothly distributed component that whose density does not change as the universe expands.