Hannover 2003 – scientific programme

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GR: Gravitation und Relativitätstheorie

GR I: HV I

GR I.1: Invited Talk

Monday, March 24, 2003, 11:00–11:45, A310

A discrete history of the Lorentzian path integral — •Renate Loll — Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, NL-3584 CE Utrecht

I will describe briefly the motivation behind a recent formulation of a non-perturbative gravitational path integral for Lorentzian (instead of the usual Euclidean) space-times, as well as its main features. At the regularized, discrete level this approach solves the problems of both defining a Wick rotation and a coordinate-invariant cutoff. Although little is known as yet about the existence and nature of a potential continuum theory in four dimensions, there are already a number of beautiful results in d=2 and d=3 where continuum limits have been found. They include an explicit example of the inequivalence of the Euclidean and Lorentzian path integrals, a non-perturbative mechanism for the cancellation of the conformal factor, and the discovery that causality can act as an effective regulator of quantum geometry. I will summarize the status quo of these No-dqLorentzian dynamical triangulationsNo-dq.