The Ricci tensor of a Robertson–Walker (RW) space-time is here specified by requiring constancy of the scalar curvature and a vanishing spatial curvature. By entering this Ricci tensor in Einstein’s equations (without cosmological constant), the cosmological fluid shows a transition from a pure radiation to a Lambda equation of state. In other words, the RW geometry with constant scalar curvature and flat space fixes the limit values w = 1/3 and w = −1, without any hypothesis on the cosmological fluid. The value of the scalar curvature fixes the time-scale for the transition. For this reason, we investigate the ‘toy-universe’ with Hubble parameter h = 0.673 and temperature TCMB = 2.72 K. The model predicts an age of the universe in the range 7.3–13.7 Gyr.

w = 1/3 to w = −1 evolution in a Robertson–Walker space-time with constant scalar curvature / L.G. Molinari, C.A. Mantica. - In: INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS. - ISSN 0219-8878. - 16:4(2019 Apr), pp. 1950061.1-1950061.9. [10.1142/S0219887819500610]

w = 1/3 to w = −1 evolution in a Robertson–Walker space-time with constant scalar curvature

L.G. Molinari
Primo
;
C.A. Mantica
Secondo
2019

Abstract

The Ricci tensor of a Robertson–Walker (RW) space-time is here specified by requiring constancy of the scalar curvature and a vanishing spatial curvature. By entering this Ricci tensor in Einstein’s equations (without cosmological constant), the cosmological fluid shows a transition from a pure radiation to a Lambda equation of state. In other words, the RW geometry with constant scalar curvature and flat space fixes the limit values w = 1/3 and w = −1, without any hypothesis on the cosmological fluid. The value of the scalar curvature fixes the time-scale for the transition. For this reason, we investigate the ‘toy-universe’ with Hubble parameter h = 0.673 and temperature TCMB = 2.72 K. The model predicts an age of the universe in the range 7.3–13.7 Gyr.
Robertson-Walker space-time; cosmology; perfect fluid
Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici
apr-2019
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/635152
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