Consistent null-energy-condition violation: Towards creating a universe in the laboratory

Abstract

Null Energy Condition (NEC) can be violated in a consistent way in models with unconventional kinetic terms, notably, in Galileon theories and their generalizations. We make use of one of these, the scale-invariant kinetic braiding model, to discuss whether a universe can in principle be created by man-made processes. We find that even though the simplest models of this sort can have both healthy Minkowski vacuum and consistent NEC-violating phase, there is an obstruction for creating a universe in a straightforward fashion. To get around this obstruction, we design a more complicated model, and present a scenario for the creation of a universe in the laboratory.

The Null Energy Condition and its violation

“…(28) that perturbations about constant π c are governed by the first term there, and L (2) = e 2πc F ′ (0)(∂χ) 2 , which is the Lagrangian for a massless scalar field. In the neighbourhood of the Minkowski background, i.e., for small ∂π c , perturbations are not superluminal [51] provided that K ′ (0) = 0, F ′′ (0) > 0. In a wide range of the functions F and K, eq.…”

“…[35], and goes under the name DBI conformal Galileon theory. To end up this Section, let us consider [51] the structure of the configuration space (π,π) of spatially homogeneous Galileons in arbitrary Galileon theory with scale invariance (27). The Lagrangian may contain all terms discussed in Section 3.…”

“…As we discuss in Section 3, there exist finite number of classes of second-derivative Lagrangians yielding second-derivative field equations [33,44,45,46]. At least some of these Lagrangians admit NEC-violation [47,48,49,50,51,52], with the NEC-violating solutions and their neighborhoods being perfectly healthy. In Section 4 we give a few examples of using these theories for constructing fairly non-trivial cosmological models and giving a proof-of-principle construction for creating a universe in the laboratory.…”

Beyond the cosmological standard model

“…They have also been used to violate the null energy condition [537,[544][545][546][547][548][549][550][551][552][553]. Covariantizing the galileons for such applications is subtle, it requires introducing non-minimal couplings to curvature, which generically destroys the shift symmetry [554][555][556][557][558] (for a construction which couples galileons covariantly to massive gravity while retaining galilean symmetry, see [559][560][561]).…”

Preinflationary genesis with CMB B-mode polarization

“…The pre-inflationary genesis requires the dramatic violation of NEC, which might have potential implications, e.g. [39], [40], [41], the upcoming Planck polarization data would tell whether it has ever occurred.…”