Einstein believed the universe could be explained by one simply theory, but he couldn't find it. Today a lot of physicists believe that the theory of everything lies in little loops of vibrating string. In this hour of To the Best of Our Knowledge, the mother of all theories — superstrings. Also, neutrinos, dark matter, and the "springy universe.

Cosmologist and science writer John Gribbin tells Jim Fleming about the recent discovery that the tiny particles called neutrinos have mass, and what it might mean for our understanding of dark matter and expanding space. Gribbin is the author of "The Case of the Missing Neutrinos." Also, former astronaut Eugene Cernan is now an aerospace executive and author of "The Last Man on the Moon." He tells Jim Fleming what it felt like to go into orbit, leave footprints on the moon, and dangle at the end of a tether during spacewalks.

Columbia University physicist Brian Greene has spent his life working on superstring theory - the Theory of Everything. He tells Steve Paulson how he got interested in string theory and why it might explain everything in the universe. Greene's book is "The Elegant Universe." Also, by day, Lynda Williams teaches physics at San Francisco State University; by night, she's the Physics Chanteuse. She explains to Judith Strasser why she sets lyrics drawn from physics to popular songs, and what the reaction is. And we hear some samples of her music. For more information you can visit her website at http://www.entersci.com

John Maddox is Editor Emeritus of "Nature." He tells Steve Paulson that scientists in the next century will work on finding out how the brain works, how life began, and how the universe got started. His book is "What Remains To Be Discovered."

Distribution dates:

• week of 04/02/2000 - hour 2
• week of 04/04/99 - hour 2