Description:

Alex Filippenko
We expected the attractive force of gravity to slow down the rate at which the Universe is expanding. But observations of very distant exploding stars (supernovae) show that the expansion rate is
actually speeding up, a Nobel-worthy discovery. Over the largest distances, the Universe seems to be dominated by a mysterious, repulsive “dark energy” that stretches space itself faster and faster. Followed by an Astronomy Q&A at 5pm.

One of the world's most highly cited astronomers, Alex Filippenko was the only person to have served on both teams that simultaneously discovered the Nobel-worthy accelerating expansion of the universe.
Voted UC Berkeley's ""Best Professor"" a record nine times, he appears frequently on TV documentaries and is addicted to observing total solar eclipses throughout the globe (16 so far).