LIRa Session: Thomas Pashby

On Friday, June 5th 2015, we will have a LIRa session with Thomas Pashby.

Everyone is cordially invited!

Speaker: Thomas Pashby

Date and Time: Friday, June 5, 2015, 14:30-16:00
Venue: Science Park 107, Room F1.15

Title: Schroedinger’s Cat, Event Times and Quantum Logic

Abstract.  I argue for a novel resolution of Schroedinger’s cat paradox by paying particular attention to the role of time and tense in setting up the problem. The quantum system at the heart of the paradoxical situation is an unstable atom, primed for indeterministic decay at some unknown time. The conventional account gives probabilities for the result of instantaneous measurements and leads to the unacceptable conclusion that the cat can neither be considered alive nor dead until the moment the box is opened (at a time of the experimenter’s choosing). To resolve the paradox I reject the status of the instantaneous quantum state as `truthmaker’ and show how a quantum description of the situation can be given instead in terms of time-dependent chance propositions concerning the time of decay, without reference to measurement.

The conclusions reached in the case of Schroedinger’s cat may be generalized throughout quantum mechanics with the means of event time observables (interpreted as conditional probabilities), which play the role of the time of decay for an arbitrary system. Conventional quantum logic restricts its attention to the lattice of projections, taken to represent possible properties of the system. I argue that event time observables provide a compelling reason to look beyond the lattice of projections to the algebra of effects, and suggest an interpretation in which propositions are made true by events rather than properties.