Nah, the second derivative of the scale factor in the second Friedmann equation (https://en.wikipedia.org/wiki/Friedmann_equations?oldformat=true#Equations http

Nah, the second derivative of the scale factor in the second Friedmann equation (https://en.wikipedia.org/wiki/Friedmann_equations?oldformat=true#Equations 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 number close to 0 (about -1/3 is a good fit for observation). Galaxies stars and atoms won't be ripped apart; instead you'll get these and structures mostly collapsing into supermassive black holes which occupy their own Hubble volumes (stray ejected stars and gas molecules will also eventually occupy their own Hubble volumes too); the difference is in the features of the cosmological horizon as observed by someone at a large distance from such a black hole and stationary with respect to it. The different horizon recession from the accelerating expansion vs the previous non-accelerating expansion produces a different (higher) temperature in the thermal bath from the cosmological horizon, and has implications for the ultimate fate of these future supermassive (and very cold) black holes. The paper your link points to is at http://arxiv.org/abs/1409.4918 http://arxiv.org/abs/1409.4918 and at equation (13) recovers p = wc^2\rho above (note that they set c to unity deliberately, which is common in physical cosmology) and on the next page they discuss their solutions for w = -1 and w = -2/3, both of which are far from the evidence we have for the density/pressure conversion constant and are only further from zero because their viscous fluid model requires that (unlike the perfect fluid in the Friedman-Lemaitre-Robertson-Walker model of the standard cosmology). (Their motivation is to unify the dark sector by reducing it to dark matter with bulk viscosity, on the logic that bulk viscosity implies negative pressure. This has been tried by others before and since, and usually results in inconsistencies that their paper hopes to avoid. The standard cosmology keeps dark matter and dark energy separate, with dark matter likely having positive pressure and it definitely dilutes away with the expansion of the universe like other matter and radiation, while dark energy is a small negative pressure everywhere that does not dilute away with the expansion of the universe.)