Wojciech Kopczynski

A non-singular universe with torsion

Abstract The problem of a spherically-symmetric gravitational field produced by spinning dust is solved in the framework of the Einstein-Cartan theory. There exists a two-parameter family of world-models without singularities of the Friedmann type.

An anisotropic universe with torsion

Abstract The problem of a spatially flat and homogeneous gravitational field produced by spinning matter is considered within the framework of the Einstein-Cartan theory. If the effect of torsion is greater than that of shear, solutions of the field equations have no cosmological singularity.

Variational principles for gravity and fluids

Abstract The paper contains a review of the technique of variational principles formulated in the language of differential forms and applied to gravitation and fluids. The gravitational theory under consideration is the Poincare gauge theory and its relation to General Relativity and the metric-teleparallel theories is investigated. Stachels perfect fluid composed of multidimensional objects is considered. A fluid of multidimensional objects with intrinsic but classical spin is also described.

Locally Sasakian manifolds

We show that every Sasakian manifold in dimensions 2k + 1 is locally generated by a free real function of 2k variables. This function is a Sasakian analogue of the Kahler potential for the Kahler geometry. It is also shown that every locally Sasakian-Einstein manifold in 2k + 1 dimensions is generated by a locally Kahler-Einstein manifold in dimension 2k.

Pure spinors in odd dimensions

The paper follows the lines of earlier papers describing spinors in even-dimensional complex and complexified vector spaces. It discusses the fundamental aspects of pure spinors and questions concerning the notion of a real index in odd-dimensional vector spaces.

The metric and the canonical energy-momentum currents in the poincaré gauge theory of gravitation

Abstract The relation between the metric (“Hilbert”) and the canonical (“Noether”) energy-momentum currents is derived in a natural way in the context of the variational formalism of the Poincare gauge theory.

Multipole moments in Kaluza-Klein theories

The problem of the motion of extended, i.e. non-point, test bodies in multidimensional space is discussed. Extended bodies are described in terms of so-called multipole moments. Using an approximate form of the equations of motion for extended bodies, deviation from geodesic motion is derived. The results are applied to a special form of spacetime.