Lifshitz Conjecture Research Articles

Space-like singularities of general relativity: A phantom menace?

The big bang and the Schwarzschild singularities are space-like. They are generally regarded as the "final frontiers" at which space-time ends and general relativity breaks down. We review the status of such space-like singularities from three increasingly more general perspectives. They are provided by (i) A reformulation of classical general relativity motivated by the Belinskii, Khalatnikov, Lifshitz conjecture on the behavior of the gravitational field near space-like singularities; (ii) The use of test quantum fields to probe the nature of these singularities; and, (iii) An analysis of the fate of these singularities in loop quantum gravity due to quantum geometry effects. At all three levels singularities turn out to be less menacing than one might a priori expect from classical general relativity. Our goal is to present an overview of the emerging conceptual picture and suggest lines for further work. In line with the \emph{Introduction to Current Research} theme, we have made an attempt to make it easily accessible to all researchers in gravitational physics.

The loop quantum cosmology bounce as a Kasner transition

For the Bianchi type I space-time (vacuum or with a massless scalar field), the loop quantum cosmology bounce can be viewed as a rapid transition between two classical solutions, with a simple transformation rule relating the Kasner exponents of the two epochs. This transformation rule can be extended to other Bianchi space-times under the assumption that during the loop quantum cosmology bounce the contribution of the spatial curvature to the Hamiltonian constraint is negligible compared to the kinetic terms. For the vacuum Bianchi type IX space-time there are transformation rules for how each of the parameters characterizing the Kasner epochs change during the bounce. This provides a quantum gravity extension to the Mixmaster dynamics of general relativity, and may have interesting implications for the Belinski–Khalatnikov–Lifshitz conjecture.

Interior dynamics of neutral and charged black holes

In this paper, we explore the interior dynamics of neutral and charged black holes. Scalar collapses in flat, Schwarzschild, and Reissner-Nordstr\"om background geometries are simulated. We examine the dynamics in the vicinities of the central singularity of a Schwarzschild black hole and of the inner horizon of a Reissner-Nordstr\"om black hole. In simulating scalar collapses in Schwarzschild and Reissner-Nordstr\"om geometries, Kruskal and Kruskal-like coordinates are used, respectively, with the presence of a scalar field being taken into account. It is found that, besides near the inner horizons of Reissner-Nordstr\"om and Kerr black holes, mass inflation also takes place near the central singularity in neutral scalar collapse. Approximate analytic expressions for different types of mass inflation are partially obtained via a close interplay between numerical and analytical approaches and an examination of the connections between Schwarzschild black holes, Reissner-Nordstr\"om black holes, neutral collapse, and charge scattering. We argue that the mass inflations near the central singularity and the inner horizon are related to the localness of the dynamics in strong gravity regions. This is in accord with the Belinskii, Khalatnikov, and Lifshitz conjecture.

Effective dynamics in Bianchi type II loop quantum cosmology

We numerically investigate the solutions to the effective equations of the Bianchi II model within the ``improved'' loop quantum cosmology dynamics. The matter source is a massless scalar field. We perform a systematic study of the space of solutions, and focus on the behavior of several geometrical observables. We show that the big bang singularity is replaced by a bounce and the pointlike singularities do not saturate the energy density bound. There are up to three directional bounces in the scale factors, one global bounce in the expansion, the shear presents up to four local maxima and can be zero at the bounce. This allows for solutions with density larger than the maximal density for the isotropic and Bianchi I cases. The asymptotic behavior is shown to behave like that of a Bianchi I model, and the effective solutions connect anisotropic solutions even when the shear is zero at the bounce. All known facts of Bianchi I are reproduced. In the ``vacuum limit,'' solutions are such that almost all the dynamics is due to the anisotropies. Since Bianchi II plays an important role in the Bianchi IX model and the Belinskii, Khalatnikov, Lifshitz conjecture, our results can provide an intuitive understanding of the behavior in the vicinity of general spacelike singularities, when loop-geometric corrections are present.

Hamiltonian formulation of the Belinskii-Khalatnikov-Lifshitz conjecture

The Belinskii, Khalatnikov and Lifshitz conjecture \cite{bkl1} posits that on approach to a space-like singularity in general relativity the dynamics are well approximated by `ignoring spatial derivatives in favor of time derivatives.' In \cite{ahs1} we examined this idea from within a Hamiltonian framework and provided a new formulation of the conjecture in terms of variables well suited to loop quantum gravity. We now present the details of the analytical part of that investigation. While our motivation came from quantum considerations, thanks to some of its new features, our formulation should be useful also for future analytical and numerical investigations within general relativity.

QUANTUM MEASUREMENTS, INFORMATION AND ENTROPY PRODUCTION

In order to understand the Landau–Lifshitz conjecture on the relationship between quantum measurements and the thermodynamic second law, we discuss the notion of "diabatic" and "adiabatic" forces exerted by the quantum object on the classical measurement apparatus. The notion of heat and work in measurements is made manifest in this approach and the relationship between information entropy and thermodynamic entropy is explored.

Low lying electronic tail spectrum of the attractive δ-potential random system by the path integral method and coherent state representation variational method

By using the path integral method to study the “partition function” and therefore the density of states of the attractive Frisch-Lloyd random system, it is found that the “partition function” is divergent. Therefore, we modify the Frisch-Lloyd model to a system with regular lattice sites on which the atoms are randomly distributed. Path integral and coherent state representation variational methods are applied to this random system; by using the effective Hamiltonian theory of a periodic potential with slowly varying envelope, the low lying tail spectrum which is consistent with the Lifshitz conjecture for a random system is obtained.