arXiv subjects

Jacek Gruszczak

Publications and source records attributed to Jacek Gruszczak.

4 recordsLinked to original sources

arXiv2012

Smooth Beginning of the Universe

The breaking down of the equivalence principle, when discussed in the context of Sikorski's differential spaces theory, leads to the definition of the so-called differentially singular boundary (d-boundary) and to the concept of differential space with singularity associated with a given space-time differential manifold. This enables us to define the time orientability, the beginning of the cosmological time and the smooth evolution for the flat Friedmanian world model with the initial singularity. The simplest smoothly evolved models are studied. It is shown, that the cosmological matter causing such an evolution can be of three different types. One of them is the fluid with dark energy properties, the second the fluid with attraction properties, and the third a mixture of the other two. Among all investigated smoothly evolved solutions, models qualitatively consistent with the observational data of type Ia supernovae have been found.

gr-qc↗

arXiv2007

Discrete Spectrum of the Deficit Angle and the Differential Structure of a Cosmic String

Differential properties of Klein-Gordon and electromagnetic fields on the space-time of a straight cosmic string are studied with the help of methods of the differential space theory. It is shown that these fields are smooth in the interior of the cosmic string space-time and that they loose this property at the singular boundary except for the cosmic string space-times with the following deficit angles : Delta=2π*(1-1/n), n=1,2,... A connection between smoothness of fields at the conical singularity and the scalar and electromagnetic conical bremsstrahlung is discussed. It is also argued that the smoothness assumption of fields at the singularity is equivalent to the Aliev and Gal'tsov "quantization" condition leading to the above mentioned discrete spectrum of the deficit angle.

gr-qc↗

arXiv1998

Gravitational Conical Bremsstrahlung and Differential Structures

Differential properties of a spin 2 boson field $ψ_{μν}$ describing propagation of gravitational perturbations on a straight cosmic string's space-time background are studied by means of methods of the differential spaces theory. It is shown that this field is a smooth one in the interior of cosmic string's space-time and looses this property at the singular boundary except for cosmic string space-times with the following deficits of angle: $Δ=2π(1-1/n) $, $n=1,2,...$. A relationship between smoothness of $ψ_{μν}$ at the singularity and the gravitational conical bremsstrahlung effect is discussed. A physical interpretation of the smoothness notion is given. It is also argued that the assumption of smoothness of $ψ_{μν}$ at the singularity plays an equivalent role to the Aliev and Gal'tsov "quantization" condition.

gr-qc↗

arXiv1995

Differential Structure of Space-Time and Physical Fields

A physical interpretation of axioms of the differential structure of space-time is presented. Consequences of such interpretation for cosmic string's space-time with a scalar field are studied. It is shown that the assumption of smoothness of the scalar field leads either to modification of cosmic string's space-time global properties or to quantization of the deficit of angle: $Δ=2π(1-1/n)$, $n=1,2,\dots$.

gr-qc↗