# Dirac cosmology and the acceleration of the contemporary universe

@article{Shao2005DiracCA, title={Dirac cosmology and the acceleration of the contemporary universe}, author={Chengyang Shao and Jianyong Shen and Bin Wang and Ru-keng Su}, journal={Classical and Quantum Gravity}, year={2005}, volume={23}, pages={3707 - 3719} }

A model is suggested to unify the Einstein general relativity and Dirac cosmology. There is one adjusted parameter b2 in our model. After adjusting the parameter b2 in the model by using the supernova data, we have calculated the gravitational constant and the physical quantities a(t), q(t) and ρr(t)/ρb(t) by using the present day quantities as the initial conditions and found that the equation of state parameter wθ equals −0.83, the ratio of the density of the addition creation ΩΛ = 0.8 and…

## 5 Citations

Dirac fields, torsion and Barbero-Immirzi parameter in Cosmology

- Physics
- 2012

We consider cosmological solution for Einstein gravity with massive fermions with a four-fermion coupling, which emerges from the Holst action and is related to the Barbero-Immirzi (BI) parameter.…

The Numbers Universe: An Outline of the Dirac/Eddington Numbers as Scaling Factors

- Physics
- 2008

The large number coincidences that fascinated theorists such as Eddington and Dirac are shown here to be a specific example of a general set of scaling factors defining universes in which fundamental…

On the action for Weyssenhoff spin fluid and the Barbero-Immirzi parameter

- Physics
- 2015

It was showed by Perez and Rovelli in 2006 that the Holst action in gravity with torsion with massless and minimally coupling Dirac fermions gives rise to the four-fermion coupling term, whose…

Stoney Scale and Large Number Coincidences

- Physics
- 2007

The Stoney scale, its characteristics and theoretical tendencies are argued to be consistent with Einstein’s theory of gravitational ether and with the Stochastic Electrodynamic theory of…

Dirac fields, torsion and Barbero-Immirzi parameter in cosmology

- 2012

## References

SHOWING 1-10 OF 39 REFERENCES

Dirac's cosmology with varying cosmological constant

- Physics
- 1994

The phenomenological approach to investigating the decay of the vacuum energy density is generalized in the spirit of Dirac's large number hypothesis. Different arguments are outlined to justify an…

The Large Numbers hypothesis and the Einstein theory of gravitation

- PhysicsProceedings of the Royal Society of London. A. Mathematical and Physical Sciences
- 1979

A study of the relations between large dimensionless numbers leads one to believe that G, expressed in atomic units, varies with the epoch. The Einstein theory requires G to be constant. One can…

Local and global variations of the fine-structure constant

- Physics
- 2004

Using the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) varying-a theory, with dark matter dominated by magnetic energy, and the spherical collapse model for cosmological structure formation, we have…

Palatini form of 1/R gravity.

- PhysicsPhysical review letters
- 2004

It is shown that the original version of this theory disagrees with solar system observations, and is equivalent to a scalar-tensor theory in which the scalar field kinetic energy term is absent from the action.

Violations of the equivalence principle in a dilaton-runaway scenario

- Physics
- 2002

We explore a version of the cosmological dilaton-fixing and decoupling mech- anism in which the dilaton-dependence of the low-energy effective action is extremized for infinitely large values of the…

Tensor-scalar cosmological models and their relaxation toward general relativity.

- PhysicsPhysical review. D, Particles and fields
- 1993

Quantitative estimates for the present level of deviation from general relativity, as measured by the post-Newtonian parameters, are derived, which give greater significance to future improvements of solar-system gravitational tests.

Physical equivalence between nonlinear gravity theories and a general-relativistic self-gravitating scalar field.

- PhysicsPhysical review. D, Particles and fields
- 1994

The global net of relationships between the nonlinear gravity theories, scalar-tensor theories, and general relativity is clarified, showing that in a sense these are ``canonically conjugated'' to each other.

Higher-order gravity theories and scalar?tensor theories

- Mathematics, Physics
- 2004

We generalize the known equivalence between higher-order gravity theories and scalar–tensor theories to a new class of theories. Specifically, in the context of a first-order or Palatini variational…

Further evidence for cosmological evolution of the fine structure constant.

- PhysicsPhysical review letters
- 2001

The results of a search for time variability of the fine structure constant alpha using absorption systems in the spectra of distant quasars find no systematic effects which can explain the results.