Hyeong-Chan Kim

Gravity from quantum information

We suggest that the Einstein equation can be derived from Landauer’s principle applied to an information erasing process at a local Rindler horizon and Jacobson’s idea linking the Einstein equation with thermodynamics. When matter crosses the horizon, information on the matter disappears, and the horizon entanglement entropy increases to compensate for the entropy reduction. The Einstein equation describes an information-energy relation during this process, which implies that entropic gravity is related to the quantum entanglement of the vacuum and has a quantuminformation theoretic origin.

Universe Driven by Perfect Fluid in Eddington-inspired Born-Infeld Gravity

We investigate the evolution of the Universe filled with barotropic perfect fluid in Eddington-inspired Born-Infeld gravity. We consider both the isotropic and the anisotropic universe. At the early stage when the energy density is high, the evolution is modified considerably compared with that in general relativity. For the equation-of-state parameter

Differential structure on κ-Minkowski spacetime realized as module of twisted Weyl algebra

w>0

Noncommutative Field Theory from twisted Fock space

, the initial singularity is not accompanied as it was discovered for radiation in earlier work. More interestingly, for pressureless dust (

Physics at the surface of a star in Eddington-inspired Born-Infeld gravity

w=0

Dark energy from forgetting

), the initial state approaches a de Sitter state. This fact opens a new possibility of singularity-free nature of the theory. The anisotropy is mild, and does not develop curvature singularities in spacetime contrary to general relativity.

Precursor of Inflation

Abstract The differential structure on the κ -Minkowski spacetime from Jordanian twist of Weyl algebra is constructed, and it is shown to be closed in 4-dimensions in contrast to the conventional formulation. Based on this differential structure, we have formulated a scalar field theory in this κ -Minkowski spacetime.

Gravity as a quantum entanglement force

We construct a quantum field theory in noncommutative space time by twisting the algebra of quantum operators (especially, creation and annihilation operators) of the corresponding quantum field theory in commutative space time. The twisted Fock space and S-matrix consistent with this algebra have been constructed. The resultant S-matrix is consistent with that of Filk [Tomas Filk, Phys. Lett. B 376, 53 (1996).]. We find from this formulation that the spin-statistics relation is not violated in the canonical noncommutative field theories.

An Analytic approach to perturbations from an initially anisotropic universe

We study phenomena happening at the surface of a star in Eddington-inspired Born-Infeld (EiBI) gravity. The star is made of particles, which are effectively described by a polytropic fluid. The EiBI theory was known to have a pathology that singularities happen at a star surface. We suggest that the gravitational back-reaction on the particles cures the problem. Strong tidal forces near the (surface) singularity modify the effective equation of state of the particles or make the surface be unstable depending on its matter contents. The geodesic deviation equations take after the Hookes law, where its frequency-squared is proportional to the scalar curvature at the surface. For a positive curvature, a particle collides with a probing wall more often and increases the pressure. With the increased pressure, the surface is no longer singular. For a negative curvature, the matters around the surface experience repulsions with infinite accelerations. Therefore, the EiBI gravity is saved from the pathology of surface singularity.

New synthesis of matter and gravity: A nongravitating scalar field

In this chapter, we present classification models based on mathematical programming approaches. We first provide an overview on various mathematical programming approaches, including linear programming, mixed integer programming, nonlinear programming and support vector machines. Next, we present our effort of novel optimization‐based classification models that are general purpose and suitable for developing predictive rules for large heterogeneous biological and medical data sets. Our predictive model simultaneously incorporates (1) the ability to classify any number of distinct groups; (2) the ability to incorporate heterogeneous types of attributes as input; (3) a high‐dimensional data transformation that eliminates noise and errors in biological data; (4) the ability to incorporate constraints to limit the rate of misclassification, and a reserved‐judgment region that provides a safeguard against over‐training (which tends to lead to high misclassification rates from the resulting predictive rule); an...We suggest that dark energy has a quantum informational origin. Landauers principle associated with the erasure of quantum information at a cosmic horizon implies the non-zero vacuum energy having effective negative pressure. Assuming the holographic principle, the minimum free energy condition, and the Gibbons-Hawking temperature for the cosmic event horizon we obtain the holographic dark energy with the parameter