Monday, July 26, 2010
The quantum mechanics of time travel through post-selected teleportation
(Submitted on 15 Jul 2010 (v1), last revised 19 Jul 2010 (this version, v2))
This paper discusses the quantum mechanics of closed timelike curves (CTC) and of other potential methods for time travel. We analyze a specific proposal for such quantum time travel, the quantum description of CTCs based on post-selected teleportation (P-CTCs). We compare the theory of P-CTCs to previously proposed quantum theories of time travel: the theory is physically inequivalent to Deutsch's theory of CTCs, but it is consistent with path-integral approaches (which are the best suited for analyzing quantum field theory in curved spacetime). We derive the dynamical equations that a chronology-respecting system interacting with a CTC will experience. We discuss the possibility of time travel in the absence of general relativistic closed timelike curves, and investigate the implications of P-CTCs for enhancing the power of computation.
Monday, July 19, 2010
A research project involving a dozen universities, French rail company SNCF, and £2.2million of EU funding has now produced advanced software that schedules trains more efficiently, including handling disruptions as they happen, with no reduction in safety, claims the Commission.
Sunday, July 18, 2010
Friday, July 16, 2010
Wednesday, July 7, 2010
"mais ce processus que je viens de dire n'importe quel français peut l'avoir" pondère notre ami le trucmuch de Rouen.
Une bien belle vidéo à visionner donc (en 19 parties je crois) :
et un article sympathique :