Ordinary matter makes up only about five percent of the mass-energy density of the universe. The other 95 percent is composed of either dark matter or dark energy. Through indirect evidence, scientists think dark matter and dark energy exist; however, they do not know what they are. Examine why dark matter and dark energy exist and some possibilities for their composition.

Leonard Duda, PhD, retired from Sandia National Laboratories after 37 years. He has been involved with volunteer science education activities including a NASA/JPL Solar System Ambassador, Science Olympiad, regional and state science fairs, and the Explora Science Center. He was Grand Awards judge co-chair at the Intel International Science and Engineering Fair.