Calendar of Physics Talks Vienna

Quantumness, Privacy, and Durability of Information
Speaker:Dr. Charles H. Bennett (IBM Research)
Abstract:The most private information, exemplified by a quantum eraser experiment, exists only conditionally and temporarily-after the experiment is over even God has forgotten what "happened". Less private are classical secrets, facts known only to a few, or information-like the lost poems of Sappho-that once was public but has now been forgotten. Finally there is information that has been replicated and propagated so widely as to be infeasible to conceal and unlikely to be forgotten. Modern information technology has caused an explosion of such information, with the beneficial side effect of making it harder for despots to rewrite the history of their misdeeds; and it is tempting to hope that all macroscopic information is permanent, making such cover-ups impossible in principle. However, by comparing entropy flows into and out of the Earth with estimates of the planet's storage capacity, we conclude that most macroscopic information-for example the pattern of sand grains on an ancient beach-is impermanent, in the sense of becoming irrecoverable by terrestrial observers while still recorded in the Universe.
Date: Wed, 27.09.2006
Time: 11:00
Location:Kleiner Hörsaal der Experimentalphysik, Strudlhofgasse 4, 2. Stock, 1090
Contact:Mag. Ursula Gerber, Institut für Experimentalphysik