Mild Inflation and Modified General Relativity in the Early Universe

ISSN： 0020-7748

Source： International Journal of Theoretical Physics, Vol.38, Iss.9, 1999-09, pp. : 2419-2440

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Abstract

This article deals with particle creation and the production of specific entropy per baryon in the early universe, which is regarded as a thermodynamically open system in the sense of Prigogine. The modified general relativity (MGR) theory of Rastall, Al-Rawaf, and Taha is employed. It contains an extra independent constant η which is peculiar to the non-Newtonian regime, besides the usual gravitational constant. Usual general relativity (GR) appears here as a special case for η = 1. With a modified thermodynamic energy conservation law, it is possible to obtain an equation for the expansion scalar by incorporating the epoch dependence of elementary particle masses. The epoch dependence of particle masses for the Robertson-Walker (RW) universe appears as a consequence of hadronic matter extension in a microlocal space-time regarded as anisotropic and Finslerian. The governing equations in the present formalism specify the equation of state and give a solution for the expansion scalar. This solution represents a mild inflationary phase in the very early universe. It is also shown that there are no ‘turn-on’ and ‘turn-off’ problems for this mild inflation. It can account for particle creation and production of specific entropy per baryon consistent with the observation. The production of specific entropy per baryon is also considered here in the MGR framework with the introduction of viscous pressure; the calculated value is in good agreement with observation for the GR case, but for the MGR case, in order to have its value within observational limits, η must lie in the range 0.75 ≤ η ≤ 1. It is also argued that this formalism does not have horizon and flatness problems.