# Time and almost-positive linear functions on algebras

## GAP Seminar

## Meeting Details

For more information about this meeting, contact Ping Xu, Mathieu Stiénon, Nigel Higson.

**Speaker:** Martin Bojowald, Penn State University

**Abstract:** One of the apparent incompatibilities between quantum mechanics and general relativity is the treatment of time as an eternal parameter in the former and as a local coordinate in the latter theory. I will describe recent ideas which try to overcome this problem by taking the algebraic view of quantum states as linear functionals on the algebra of observables. A time variable may then be taken as an element of the algebra in order to describe evolution locally, while transformations between different time choices must be made for long-term evolution resembling a manifold picture. Algebraic states that include time in this sense violate the usual positivity condition, but still obey a weaker form of almost-positive linear functionals.

## Room Reservation Information

**Room Number:** 106 McAllister

**Date:** 02/03/2015

**Time:** 2:30pm - 3:30pm