Natural affinors on time-dependent Weil bundles
Nature of the central singularity in Szekeres models
The occurrence and nature of the central naked singularity in aspherical Szekeres models is investigated here, and the strength of the singularity is discussed. The implications for the cosmic censorship hypothesis are considered.
New results on de Sitter quantum field theory
Newton transformations on null hypersurfaces
Any rigged null hypersurface is provided with two shape operators: with respect to the rigging and the rigged vector fields respectively. The present paper deals with the Newton transformations built on both of them and establishes related curvature properties. The laters are used to derive necessary and sufficient conditions for higher-order umbilicity and maximality we introduced in passing, and develop general Minkowski-type formulas for the null hypersurface, supported by some physical models...
Noncommutative Lagrange mechanics.
Nonexistence of axially symmetric, stationary solution of Einstein vacuum equation with disconnected symmetric event horizon.
Nonexistence of Petrov type III space-times on which Weyl's neutrino equation or Maxwell's equations satisfy Huygens' principle
Non-Hermitian quantum systems and time-optimal quantum evolution.
Non-Riemannian gravitational interactions
Recent developments in theories of non-Riemannian gravitational interactions are outlined. The question of the motion of a fluid in the presence of torsion and metric gradient fields is approached in terms of the divergence of the Einstein tensor associated with a general connection. In the absence of matter the variational equations associated with a broad class of actions involving non-Riemannian fields give rise to an Einstein-Proca system associated with the standard Levi-Civita connection.
Null geodesic congruences, asymptotically-flat spacetimes and their physical interpretation.