The quantization of Lorentzian or Euclidean 2+1 gravity by canonical methods is a well-studied problem. However, the constraints of 2+1 gravity are those of a topological field theory and therefore resemble very little those of the corresponding Lorentzian 3+1 constraints. In this paper we canonically quantize Euclidean 2+1 gravity for arbitrary genus of the spacelike hypersurface with new, cla...

For a space–time, the question whether two causally related points can be joined by means of a causal geodesic has a clear physical meaning. More geometrically, geodesic connectedness ~the possibility of joining any two points by a geodesic of any causal type! is a basic property. Some techniques introduced to study geodesic connectedness are appliable to related problems of physical interest, ...

We introduce a gauge and diffeomorphism invariant theory on Yang-Mills phase space. The theory is well defined for an arbitrary gauge group with an invariant bilinear form, it contains only first class constraints, and the spacetime metric has a simple form in terms of the phase space variables. With gauge group SO(3, C), the theory equals the Ashtekar formulation of gravity with a cosmological...

The effects of additive white noise upon the dynamics of a system described by its Hopf normal form are investigated, with particular reference to the well-known model of a detuned single-mode laser. The power spectrum corresponding to the laser amplitude is determined by finite-difference solution of a partial differential equation, and analytical formulas are determined in the asymptotic limi...

*Correspondence: Rudolf A. Treumann, International Space Science Institute, Hallerstrasse 6, CH-3012 Bern, Switzerland e-mail: [email protected] We propose a generalization of Gibbs’ statistical mechanics into the domain of non-negligible phase space correlations. Derived are the probability distribution and entropy as a generalized ensemble average, replacing Gibbs-Boltzmann-Shannon’s entro...

darabgird is one of the ancient cities in fars province. according to iranian mythology, darab shah (dariush, the great) found the city in the achaemenid period. but, due to the fact that 1.21% of total ceramics gathered from the city belongs to the parthian era, we can accept that the city remained in use since parthian period to the islamic era. data analysis shows that the city had a strong...

Starting from the space of Lorentzian metrics, we examine the full gravitational path integral in 3 and 4 space-time dimensions. Inspired by recent results obtained in a regularized, dynamically triangulated formulation of Lorentzian gravity, we gaugefix to proper-time coordinates and perform a non-perturbative “Wick rotation” on the physical configuration space. Under certain assumptions about...