Spin and Torsion May Avert Gravitational Singularities

Trautman, Andrzej

doi:10.1038/physci242007a0

Cited by 233 publications

(199 citation statements)

References 14 publications

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“…However, the models obeying the 'cosmological principle', i.e., the large scale homogeneity and isotropy of the Universe, are of more significance for obvious observational reasons. Although some bouncing solutions were found in presence of torsion in the past [11], the present work reexamines these scenarios in a homogeneous and isotropic cosmological model originated from a background spacetime with torsion along with dilaton.…”

Section: Introductionmentioning

confidence: 96%

“…On the contrary, a repulsive (anti-gravitating) character of torsion is well known in the context of cosmologies based on Einstein-Cartan theory. Bouncing cosmological solutions have already been shown to exist in Bianchi type torsioned spacetimes [11]. Thus one is led to the fact that even when torsion is generated by the hitherto attractive KR field in string background geometries of Riemannian type, the repulsive character of torsion may still be restored via the nature of its coupling with the KR field within the minimal coupling prescription when σ > 0 (or, in other words when the effective KR energy density is negative).…”

Section: General Formalismmentioning

confidence: 99%

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Does curvature–dilaton coupling with a Kalb–Ramond field lead to an accelerating Universe?

SenGupta

Sur

2003

J. Cosmol. Astropart. Phys.

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In this work we show that the Universe evolving in a spacetime with torsion (originated from a second rank antisymmetric Kalb-Ramond field) and dilaton is free from any big bang singularity and can have acceleration during the evolution. Both the matter and radiation dominated era have been considered and the role of the dilaton to explain the decelerating phase in the earlier epoch has also been discussed.

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Section: Introductionmentioning

confidence: 96%

Section: General Formalismmentioning

confidence: 99%

Does curvature–dilaton coupling with a Kalb–Ramond field lead to an accelerating Universe?

SenGupta

Sur

2003

J. Cosmol. Astropart. Phys.

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“…It is considerably interesting to point out that the calculational techniques developed in Section 4 can supply geometric tools for describing the propagation of gravitons and Dirac particles in torsional cosmic environments, in combination with the mechanisms that may avert gravitational singularities as particularly exhibited in Ref. [43].…”

Section: Concluding Remarks and Outlookmentioning

confidence: 99%

“…The main motivation for formulating this torsional extension came from the ascertainment that its geometric inner structure may allow the implementation of a ne contributions which a ord gauge invariant vector potentials bearing an observable character. It had then been expected that the de nitive ascription of a fundamental signi cance to spacetime torsion would eventually become more tangible if a torsional two-component spinor description of dark energy might go hand-in-hand with the spin-torsion mechanisms that prevent the universe from being originated by a singularity [42][43][44].…”

Section: Introductionmentioning

confidence: 99%

A local description of dark energy in terms of classical two-component massive spin-one uncharged fields on spacetimes with torsionful affinities

Cardoso

2015

Open Physics

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It is assumed that the two-component spinor formalisms for curved spacetimes that are endowed with torsionful a ne connexions can supply a local description of dark energy in terms of classical massive spin-one uncharged elds. The relevant wave functions are related to torsional a ne potentials which bear invariance under the action of the generalized Weyl gauge group. Such potentials are thus taken to carry an observable character and emerge from contracted spin a nities whose patterns are chosen in a suitable way. New covariant calculational techniques are then developed towards deriving explicitly the wave equations that supposedly control the propagation in spacetime of the dark energy background. What immediately comes out of this derivation is a presumably natural display of interactions between the elds and both spin torsion and curvatures. The physical properties that may arise directly from the solutions to the wave equations are not brought out.

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“…Torsion is important from the phenomenological point of view and it may be relevant to cosmology. This importance is associated with the modifications of kinematic quantities like shear, vorticity, acceleration, expansion and their evolution equations derived in the presence of torsion [24,33,34,35,36].…”

Section: Introductionmentioning

confidence: 99%

Cosmic optical activity in the spacetime of a scalar-tensor screwed cosmic string

2003

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Measurements of radio emission from distant galaxies and quasars verify that the polarization vectors of these radiations are not randomly oriented as naturally expected. This peculiar phenomenon suggests that the spacetime intervening between the source and observer may be exhibiting some sort of optical activity, the origin of which is not known. In the present paper we provide a plausible explanation to this phenomenon by investigating the rôle played by a Chern-Simons-like term in the background of an ordinary or superconducting screwed cosmic string in a scalar-tensor gravity. We discuss the possibility that the excess in polarization of the light from radio-galaxies and quasars can be understood as if the electromagnetic waves emitted by these cosmic objects interact with a scalar-tensor screwed cosmic string through a Chern-Simons coupling. We use current astronomical data to constrain possible values for the coupling constant of this theory, and show that it turns out to be: λ ∼ 10 −26 eV, which is two orders of magnitude larger than in string-inspired theories.]

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Spin and Torsion May Avert Gravitational Singularities

Cited by 233 publications

References 14 publications

Does curvature–dilaton coupling with a Kalb–Ramond field lead to an accelerating Universe?

Does curvature–dilaton coupling with a Kalb–Ramond field lead to an accelerating Universe?

A local description of dark energy in terms of classical two-component massive spin-one uncharged fields on spacetimes with torsionful affinities

Cosmic optical activity in the spacetime of a scalar-tensor screwed cosmic string

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