November 6, 2002: Time Travel and Cosmology - Lawrence M. Krauss

Art Bell welcomes theoretical physicist Lawrence M. Krauss, professor of physics and astronomy at Case Western Reserve University, for a wide-ranging conversation on time travel, cosmology, and the nature of the universe. The discussion begins with Einstein's special and general relativity, exploring how clocks slow down near massive objects and at high speeds, with Krauss explaining how cosmic ray muons prove time dilation every time a Geiger counter clicks.

The conversation turns to the theoretical possibility of traveling backward in time through exotic constructs like wormholes, which would require gravitationally repulsive material unlike anything observed in nature. Krauss walks through the mechanics of how a traversable wormhole could function as a time machine, while acknowledging the staggering energy requirements involved. He also addresses the grandmother paradox and its limited proposed solutions, including the unsatisfying causality loop.

Art and Krauss explore the Big Bang, tracing the universe back to a point smaller than a baseball, and discuss the evidence supporting cosmological theory through precise predictions of elemental abundances. They also touch on the likelihood of extraterrestrial life, the multiverse concept, and why interstellar travel remains practically impossible given current physics. The first hour features open lines on implantable microchips, the biblical Mark of the Beast, and Buddhist perspectives on ghosts.