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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 |
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