You need not be afraid of phantom energy

Abstract

Phantom energy which violates the dominant-energy condition and is not excluded by current constraints on the equation of state may be dominating the evolution of the universe now. It has been pointed out that in such a case the fate of the universe may be a big rip where the expansion is so violent that all galaxies, planets and even atomic nuclei will be successively ripped apart in finite time. Here we show, however, that there are certain unified models for dark energy which are stable to perturbations in matter density where the presence of phantom energy does not lead to such a cosmic doomsday.