Zobrazeno 1 - 10
of 706
pro vyhledávání: '"Nikodem J"'
Autor:
Popławski, Nikodem J.
We consider a hypothesis that the closed Universe was formed on the other side of the event horizon of a black hole existing in another universe. That black hole appears in the Universe as a boundary white hole, and its rest frame in comoving coordin
Externí odkaz:
http://arxiv.org/abs/1912.02173
Publikováno v:
Class. Quantum Grav. 37, 025011 (2020)
We analyze the dynamics of a homogeneous and isotropic universe in the Einstein--Cartan theory of gravity. The spin of fermions produces spacetime torsion that prevents gravitational singularities and replaces the big bang with a nonsingular big boun
Externí odkaz:
http://arxiv.org/abs/1906.11824
Autor:
Popławski, Nikodem J.
Publikováno v:
Eur. Phys. J. C 79, 734 (2019)
The measurements of the Hubble parameter using the cosmic microwave background radiation appear to be inconsistent with the measurements of this parameter using Cepheid variable stars. This inconsistency may be a result of using the $\Lambda$CDM cosm
Externí odkaz:
http://arxiv.org/abs/1906.03947
Autor:
Popławski, Nikodem J.
Publikováno v:
Mod. Phys. Lett. A 35, 2050331 (2020)
We show that a scalar field without a kinetic term in the Lagrangian density, coupled to the covariant divergence of the torsion vector in the Einstein$-$Cartan theory of gravity, becomes kinetic in its general-relativistic equivalent formulation. Th
Externí odkaz:
http://arxiv.org/abs/1512.09365
Autor:
Desai, Shantanu, Poplawski, Nikodem J.
Publikováno v:
Phys. Lett. B 755, 183 (2016)
The coupling between spin and torsion in the Einstein-Cartan-Sciama-Kibble theory of gravity generates gravitational repulsion at very high densities, which prevents a singularity in a black hole and may create there a new universe. We show that quan
Externí odkaz:
http://arxiv.org/abs/1510.08834
Autor:
Poplawski, Nikodem J.
Publikováno v:
Astrophys. J. 832, 96 (2016)
The conservation law for the angular momentum in curved spacetime requires that the antisymmetric part of the affine connection (the torsion tensor) is a variable in the principle of least action. The coupling between spin and torsion generates gravi
Externí odkaz:
http://arxiv.org/abs/1410.3881
Autor:
Poplawski, Nikodem J.
We study cosmological perturbations arising from thermal fluctuations in the big-bounce cosmology in the Einstein-Cartan-Sciama-Kibble theory of gravity. We show that such perturbations cannot have a scale-invariant spectrum if fermionic matter minim
Externí odkaz:
http://arxiv.org/abs/1201.0316
Autor:
Poplawski, Nikodem J.
If spacetime torsion couples to the intrinsic spin of matter according to the Einstein-Cartan-Sciama-Kibble theory of gravity, then the resulting gravitational repulsion at supranuclear densities prevents the formation of singularities in black holes
Externí odkaz:
http://arxiv.org/abs/1110.5019
Autor:
Poplawski, Nikodem J.
We derive a relation between the two polarization modes of a plane, linear gravitational wave in the second-order approximation. Since these two polarizations are not independent, an initially monochromatic gravitational wave loses its periodic chara
Externí odkaz:
http://arxiv.org/abs/1110.0051
Autor:
Poplawski, Nikodem J.
We consider the Lagrangian density for a free Maxwell field, in which the electromagnetic field tensor minimally couples to the affine connection, in the Einstein-Cartan-Sciama-Kibble theory of gravity. We derive the formulae for the torsion and elec
Externí odkaz:
http://arxiv.org/abs/1108.6100