Shestakova, T. P.
Published in
Gravitation and Cosmology

—The paper is devoted to some of the difficulties which the Wheeler-DeWitt quantum geometrodynamics encountered, in particular, a strong mathematical proof that this theory is gauge-invariant, the definition of the wave function of the Universe through a path integral and the illegality of asymptotic boundary conditions in quantum gravity, the deri...

Pavlov, Yu. V. Zaslavskii, O. B.
Published in
Gravitation and Cosmology

In the recent years, it was found that the energy Ec.m. in the center of mass frame of two colliding particles can be unbounded near black holes. If a collision occurs precisely on the horizon, Ec.m. is formally infinite. However, in any physically reasonable situation this is impossible. We collect different scenarios of this kind and show why in ...

Sanchez, Norma G.
Published in
Gravitation and Cosmology

Starting from quantum theory (instead of general relativity) to approach quantum gravity within a minimal setting allows us here to describe the quantum space-time structure and the quantum light cone. From the classical-quantum duality and quantum harmonic oscillator (X, P) variables in global phase space, we promote the space-time coordinates to ...

Santini, E. Sergio
Published in
Gravitation and Cosmology

A certain approach to solving the Wheeler-DeWitt equation in quantum cosmology, based on a type of super-selection rule by which negative frequency solutions are discarded, is discussed. In a preliminary analysis: we recall well-known results in relativistic quantum field theory, showing that adopting this approach of super-selection by discarding ...

Abishev, M. E. Ivashchuk, V. D. Malybayev, A. N. Toktarbay, S.
Published in
Gravitation and Cosmology

Dilatonic black hole dyon-like solutions are overviewed in the gravitational 4D model with a scalar field, two 2-forms, two dilatonic coupling constants λi ≠ 0, i = 1, 2, obeying λ1 ≠ − λ2, and the sign parameter ε = ±1 before the scalar field kinetic term. Here ε = −1 corresponds to a phantom scalar field. The solutions are defined up to solutions...

Yurova, A. A. Yurov, A. V. Yurov, V. A.
Published in
Gravitation and Cosmology

An anthropic explanation of the evident smallness of the dark energy (DE) density value implies the existence of a time-dependent component of the scalar field, serving, together with a negative-valued cosmological constant, as one of two components to the overall DE density. The observers (i.e. us) might then only evolve in those regions of the un...

Ennadifi, Salah Eddine Douhou, Karim
Published in
Gravitation and Cosmology

One of the most accepted ideas in modern cosmology to explain a number of puzzling astronomical observations is the existence of Dark Matter in the Universe, even though it has not been directly observed. We recall the motivation for its existence according to its influence on visible matter and its characteristics in terms of famous candidate part...

Ignat’ev, Yu. G.
Published in
Gravitation and Cosmology

The article discusses and substantiates a self-consistent approach to the macroscopic description of systems with gravitational interaction. Corrections to the equation of state of the fluid are found, based on the macroscopic Einstein equations which were obtained by averaging over microscopic spherically symmetric metric fluctuations created by p...

Sevinc, Özgür Aydiner, Ekrem
Published in
Gravitation and Cosmology

Using variable gravitational and cosmological constants, the mechanism of particle creation in the universe is studied for Friedmann–Robertson–Walker (FRW) space-times at high dimensions to explain the early deceleration and present accelerating phases. To investigate the dynamics of these phases, we consider two scale factor of the forms a(t)=tαet...

Lelyakov, A. P.
Published in
Gravitation and Cosmology

The paper studies the influence of periodically changing boundary conditions on the motion of a test null string “inside” an axially symmetric null string domain that has a layered structure and preserves its size. It is shown that the action of the gravitational field of the null string domain on a test null string whose size (radius) is smaller t...