Horizon - Season 53 Episode 3 The Mystery of Dark Energy
Overview: Examining Dark Energy, the mysterious force that is unexpectedly causing the universe's expansion to speed up. Its effects were discovered in 1998, but physicists still do not know what it is, and its very existence calls into question Albert Einstein's General Theory of Relativity; the cornerstone of modern physics. The hunt for the identity of Dark Energy is on, and although experiments conducted on earth and in space generate data that might provide a clue, physics is hoping another Einstein might emerge and write a new theory that explains the mystery.