A kinetic theory of diffusion in general relativity with cosmological scalar field
- Departamento de Matemática Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain)
A new model to describe the dynamics of particles undergoing diffusion in general relativity is proposed. The evolution of the particle system is described by a Fokker-Planck equation without friction on the tangent bundle of spacetime. It is shown that the energy-momentum tensor for this matter model is not divergence-free, which makes it inconsistent to couple the Fokker-Planck equation to the Einstein equations. This problem can be solved by postulating the existence of additional matter fields in spacetime or by modifying the Einstein equations. The case of a cosmological scalar field term added to the left hand side of the Einstein equations is studied in some details. For the simplest cosmological model, namely the flat Robertson-Walker spacetime, it is shown that, depending on the initial value of the cosmological scalar field, which can be identified with the present observed value of the cosmological constant, either unlimited expansion or the formation of a singularity in finite time will occur in the future. Future collapse into a singularity also takes place for a suitable small but positive present value of the cosmological constant, in contrast to the standard diffusion-free scenario.
- OSTI ID:
- 22280257
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2011, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
Similar Records
Phenomenological dynamics of loop quantum cosmology in Kantowski-Sachs spacetime
The Hamiltonian formalism for scalar fields coupled to gravity in a cosmological background