Search Talks

We show that the entropy resulting from the counting of microstates of non extremal black holes using field theory duals of string theories can be interpreted as arising from entanglement. The conditions for making such an interpretation consistent are discussed. First, we interpret the entropy (and thermodynamics) of spacetimes with non degenerate, bifurcating Killing horizons as arising from entanglement. We use a path integral method to define the Hartle-Hawking vacuum state in such spacetimes and discuss explicitly its entangled nature and its relation to the geometry. If string theory on such spacetimes has a field theory dual, then, in the low-energy, weak coupling limit, the field theory state that is dual to the Hartle-Hawking state is a thermofield double state. This allows the comparison of the entanglement entropy with the entropy of the field theory dual, and thus, with the Bekenstein-Hawking entropy of the black hole. As an example, we discuss in detail the case of the five dimensional anti-de Sitter, black hole spacetime.

In 1905, Norwegian explorer Roald Amundsen completed the first ever transit of the fabled Northwest Passage, culminating a centuries long quest that had claimed ships and lives. Amundsen\'s feat was one of many human achievements in the first decade of the new century, and a landmark in the history exploration. Amundsen\'s voyage was preceded by the controversial North Pole expedition of Robert Peary, another long sought prize of explorers. Amundsen\'s quests shifted south to Antarctica and the South Pole, a prize he achieved, and then back to the Arctic, when he tried and failed to navigate, locked in the polar ice, to the North Pole. This presentation will examine the life, feats, trials, failures and successes of Amundsen. James P.Delgado, Roald Amundsen, northwest passage, north pole, south pole, exploration, Arctic, Frobisher, Peary, Franklin, Clark, Ross, Mclure,

How has the most celebrated scientific theory of the 20th century held up under the exacting scrutiny of planetary probes, radio telescopes and atomic clocks? After 100 years, was Einstein right? Clifford Will, Einstein, general relativity, spacetime, gravity wave, mercury perihelion, light, radioastronomy, gravititational lenses, quasars, pulsar

The problem of vacuum energy is reviewed. The observational evidence in favor of a non-zero cosmological constant is described. I then discuss several possible explanations for how a theoretically natural huge value of vacuum energy could be adjusted down to the unnaturally tiny but observed value.