J'aurai le plaisir de faire un exposé au séminaire du LPT d'Orsay Jeudi 8/10. Je recopie ci-dessous les infos pratiques et l'abstract.
Jeudi 8 octobre 2015, 14:30, au LPT, 114
On the interplay between noncommutativity and causality.
Noncommutative geometry is based on the observation that geometric notions can be defined in an algebraic way, and that the algebraic definition remains meaningful and gains in generality when the assumption of commutativity is removed. In this talk we will explain how order-theoretic notions can be introduced into this scheme, giving rise to noncommutative ordered spaces. We will show on the simple though important example of almost-commutative manifolds that two causally connected events cannot be arbitrarily close together when the algebra is not commutative. Since, as we will argue, noncommutative ordered spaces can be expected to show up in Lorentzian noncommutative geometry as well as in quantum gravity, this result might have some relevance in both areas. We will start from scratch, give many examples, and compare our framework with another approach, based on Lorentzian spectral triples, which is due to Franco.