An anisotropic universe with torsion

Kopczyński, Wojciech

doi:10.1016/0375-9601(73)90546-x

Cited by 105 publications

(63 citation statements)

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“…Although the spin-spin contact interaction term appears to be negligibly small even in what may be regarded now as superdense matter, it may play an essential role when the ratio approaches unity, i.e., in the earliest stages of evolution of the Universe. The spin-spin term produces something which may be called after Kopczynski the "centrifugal force" and which is able to prevent the occurrence of singularities in cosmology [9,10].…”

Section: /3mentioning

confidence: 99%

“…The second, more satisfactory way to introduce the intrinsic angular momentum is by generalizing the structure of spacetime. It was done by Cartan by assuming the metric and the non-symmetric affine connection as independent quantities and was further developed by Hehl [7], Trautman [8] and Kopczynski [9,10]. This assumption allowed a definition of the torsion of spacetime and its connection with the torsion with spin.…”

Section: Introductionmentioning

confidence: 99%

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Cosmological model with macroscopic spin fluid

Szydłowski

Krawiec

2004

Phys. Rev. D

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We consider a Friedmann-Robertson-Walker cosmological model with some exotic perfect fluid with spin known as the Weyssenhoff fluid. The possibility that the dark energy may be described in part by the Weyssenhoff fluid is discussed. The observational constraint coming from supernovae type Ia observations is established. This result indicates that, whereas the cosmological constant is still needed to explain current observations, the model with spin fluid is admissible. For high redshifts z > 1 the differences between the model with spin fluid and the cold dark matter model with a cosmological constant become detectable observationally for the flat case with Ωm,0 = 0.3. From the maximum likelihood method we obtain the value of Ωs,0 = 0.004 ± 0.016. This gives us the limit Ωs,0 > −0.012 at the 1σ level. While the model with "brane effects" is preferred by the supernovae Ia data, the model with spin fluid is statistically admissible. For comparison, the limit on the spin fluid coming from cosmic microwave background anisotropies is also obtained. The uncertainties in the location of a first peak give the interval −1.4 × 10 −10 < Ωs,0 < −10 −10 . From big bang nucleosynthesis we obtain the strongest limit Ωs,0 > ∼ −10 −20 . The interconnection between the model considered and brane models is also pointed out.

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Section: /3mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cosmological model with macroscopic spin fluid

Szydłowski

Krawiec

2004

Phys. Rev. D

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“…at the late stages of collapse scenario or in the early times of the evolution of the universe. Such effects could provide non-singular cosmological [120,121,149,150] as well as astrophysical settings [151]. However, during such extreme regimes, though the weak (or null) energy condition may be violated due to the negative pressure contribution due to the spin contribution, the total energy density as given in Eq.…”

Section: Emergence Of Spacetime In Einstein-cartan Theorymentioning

confidence: 99%

“…This Riemann-Cartan geometry is usually denoted by U 4 in order to distinguish it from the Riemannian geometry. After Cartan's research, many other efforts have been made by Hehl [116][117][118][119], Trautman [120,121] and Kopczynski [122,123] to bring spin into the curved spacetime. This approach allowed one to define the torsion of spacetime and its connection with spin.…”

Section: Introductionmentioning

confidence: 99%

Emergent cosmos in Einstein–Cartan theory

et al. 2018

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Based on Padmanabhan's proposal, the accelerated expansion of the universe can be driven by the difference between the surface and bulk degrees of freedom in a region of space, described by the relation dV /dt = N sur − N bulk where N sur and N bulk = −N em + N de are the degrees of freedom assigned to the surface area and the matter-energy content inside the bulk such that the indices "em" and "de" represent energy-momentum and dark energy, respectively. In the present work, the dynamical effect of the Weyssenhoff perfect fluid with intrinsic spin and its corresponding spin degrees of freedom in the framework of Einstein-Cartan (EC) theory are investigated. Based on the modification of Friedmann equations due to the spin-spin interactions, a correction term for Padmanabhan's original relation dV /dt = N sur +N em −N de including the number of degrees of freedom related with these spin interactions is obtained through the modification in N bulk term as N bulk = −N em + N spin + N de leading to dV /dt = N sur + N em − N spin − N de in which N spin is the corresponding degrees of freedom related with the intrinsic spin of the matter content of the universe. Moreover, the validity of the unified first law and the generalized second law of thermodynamics for the Einstein-Cartan cosmos are investigated. Finally, by considering the covariant entropy conjecture and the bound resulting from the emergent scenario, a total entropy bound is obtained. Using this bound, it is shown that the for the universe as an expanding thermodynamical system, the total effective Komar energy never exceeds the square of the expansion rate with a factor of 3 4π .

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“…The energy-momentum tensor T µν satisfies the conservation equation ∇ µ T µν = 0. In this work we are interested in a particular cosmological solution to the above equations first introduced in [24]. This space-time has the following line element…”

Section: Cosmological Modelmentioning

confidence: 99%

Torsion-induced spin precession

Mohseni

2008

Eur. Phys. J. C

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We investigate the motion of a spinning test particle in a spatially-flat FRW-type space-time in the framework of the Einstein-Cartan theory. The space-time has a torsion arising from a spinning fluid filling the space-time. We show that for spinning particles with nonzero transverse spin components, the torsion induces a precession of particle spin around the direction of the fluid spin. We also show that a charged spinning particle moving in a torsion-less spatially-flat FRW space-time in the presence of a uniform magnetic field undergoes a precession of a different character.

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An anisotropic universe with torsion

Cited by 105 publications

References 1 publication

Cosmological model with macroscopic spin fluid

Cosmological model with macroscopic spin fluid

Emergent cosmos in Einstein–Cartan theory

Torsion-induced spin precession

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