“Introduction to Astrophysics” S:1 E:24 The History of the Universe

S:1 E:24 The History of the Universe In this last episode, follow the trail of the greatest unsolved problem in astrophysics. Along the way, get a grip on the past, present, and future of the universe. Discovered in the 1990s, the problem is “dark energy,” which is causing the expansion of the universe to accelerate. Trace this mysterious force to the lambda term in the celebrated Friedmann equation, proposed in the 1920s.