Phantom Energy: Dark Energy withw<−1Causes a Cosmic Doomsday

Abstract

We explore the consequences that follow if the dark energy is phantom energy, in which the sum of the pressure and energy density is negative. The positive phantom-energy density becomes infinite in finite time, overcoming all other forms of matter, such that the gravitational repulsion rapidly brings our brief epoch of cosmic structure to a close. The phantom energy rips apart the Milky Way, solar system, Earth, and ultimately the molecules, atoms, nuclei, and nucleons of which we are composed, before the death of the Universe in a "big rip."

Oxidised cosmic acceleration

“…But, even if such terms prevent pathologies, by repackaging all of the higher-derivative terms on one side of the field equations and the Einstein tensor on the other, we obtain an "effective" stress-energy which violates the NEC. This means that a variety of exotic solutions to Einstein's equations which require NEC-violating matter could potentially be permitted [37,38,39,40,45,46,47,48], but this must be checked on a case-by-case basis. It would be interesting if we were forced to accept the possibility of exotic solutions of Einstein's equations, or modifications to gravity, from observations that the universe is currently accelerating.…”

“…There are some rigorous formulations of this belief, where NEC violation is shown to lead to superluminal propagation, instabilities, and violations of unitarity or causality [30,31,32,33,34,35,36]. Certainly the NEC forbids a number of solutions to Einstein's equations with strange properties: traversable wormholes [37,38], superluminal "warp drives" [39,40,41,42,43,44], time machines [45,46], universes with big rip singularities [47,48], and pathologies with gravitational thermodynamics [49,50,51,52,53] are possible with NECviolating "exotic" matter. 2 (If one considers non-Einstein gravity, these conclusions may differ: for example, the NEC can be violated by a scalar field in Brans-Dicke gravity in Jordan frame [54] without allowing wormholes [55]).…”

Avoidance of big rip in phantom cosmology by gravitational back reaction

“…This arises because [11,15] the energy density of phantom fields increases with time instead of redshifting away as the matter or radiation energy densities or as the energy density of ordinary quintessence. Thus the increasing phantom energy will ultimately strip apart gravitationally bound bodies and cause a cosmic doomsday or big rip [15].…”

“…This arises because [11,15] the energy density of phantom fields increases with time instead of redshifting away as the matter or radiation energy densities or as the energy density of ordinary quintessence. Thus the increasing phantom energy will ultimately strip apart gravitationally bound bodies and cause a cosmic doomsday or big rip [15]. The above conclusions are based upon a constant negative value of w. However, if the value of w could change during the evolution of the universe and then in principle the big rip can be avoided [12].…”

Energy in an expanding universe in the teleparallel geometry

“…Finally, for the hyperbolic universe (k = −1), the energy diverges in the interval of integration [0, 2]. Any possible infinity energy in the universe could lead to "big rip" type singularities [35].…”