arXiv:1409.4918gr-qc
A New Approach to Cosmological Bulk Viscosity
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Abstract
We examine the cosmological consequences of an alternative to the standard expression for bulk viscosity, one which was proposed to avoid the propagation of superluminal signals without the necessity of extending the space of variables of the theory. The Friedmann equation is derived for this case, along with an expression for the effective pressure. We find solutions for the evolution of the density of a viscous component, which differs markedly from the case of conventional Eckart theory; our model evolves toward late-time phantom-like behavior with a future singularity. Entropy production is addressed, and some similarities and differences to approaches based on the Mueller-Israel-Stewart theory are discussed.
Nah, the second derivative of the scale factor in the second Friedmann equation (https://en.wikipedia.org/wiki/Friedmann_equations?oldformat=...) is still determined by energy-density (rho) and pressure (p). "p", pressure, is equal to w \rho c^2, where w is a small negative…
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