24 research outputs found
Negative potentials and collapsing universes
No full textWe study Friedmann–Robertson–Walker models with a perfect fluid matter source and a scalar field nonminimally coupled to matter. We prove that a general class of bounded from above potentials which fall to minus infinity as the field goes to minus infinity, forces the Hubble function to diverge to −∞ in a finite time. This finite-time singularity theorem is true for the arbitrary coupling coefficient, provided that it is a bounded function of the scalar field
The recollapse problem of closed Friedmann–Robertson–Walker models in higher-order gravity theories
No full text
Comment on “Cyclic universe with an inflationary phase from a cosmological model with real gas quintessence”
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Comment on "Existence of Einstein static universes and their stability in fourth-order theories of gravity"
No full textIt is argued that the solution space of the equation determining the class of f(R) theories which admit an Einstein static universe should be broadened by including the algebraic roots
