Dark Energy and the Runaway Universe

Astronomers have long known that the universe is expanding, but assumed that it would slow to a halt and then collapse. More recent observations of bright, exploding supernovae reveal that not only is the universe accelerating, an enigmatic “dark energy” is stretching it apart, creating a runaway universe. What dark energy is — and where it comes from — may be the greatest unsolved puzzle in all of physics. Hear global astronomy superstar and renowned Berkeley professor Alex Filippenko unravel the mysteries of the cosmos.