This interesting video explains dark matter and how it applies to the universe.
In this video, Saul Perlmutter explains how dark energy, which makes up 70 percent of the universe, is causing our universe to expand.
Come up with questions about a topic and learn new vocabulary words to determine answers using an Ask, Answer, Learn table.
Einstein devised the cosmological constant to explain a static universe, but when the universe was found to be expanding he called it a blunder. But it might be real; it might be dark energy.