Jeong-Young Ji

Action and entropy of black holes in spacetimes with a cosmological constant

In the Euclidean path-integral approach, we calculate the actions and the entropies for the Reissner-Nordstrom-de Sitter solutions. When the temperatures of black hole and cosmological horizons are equal, the entropy is the sum of one-quarter areas of black hole and cosmological horizons; when the inner and outer black hole horizons coincide, the entropy is only one-quarter area of the cosmological horizon and the entropy vanishes when the two black hole horizons and cosmological horizon coincide. We also calculate the Euler numbers of the corresponding Euclidean manifolds, and discuss the relationship between the entropy of instanton and the Euler number.

POWER LAWS IN NONLINEAR GRANULAR CHAIN UNDER GRAVITY

The signal generated by a weak impulse propagates in an oscillatory way and dispersively in a gravitationally compacted granular chain. For the power-law type contact force, we show analytically that the type of dispersion follows power-laws in depth. The power-law for grain displacement signal is given by

Existence criterion of solitary waves in a chain of grains

h^{-1/4(1-1/p)}

Hairs on the cosmological horizon

where

INTERFERENCE PHENOMENA IN THE PHOTON PRODUCTION BETWEEN TWO OSCILLATING WALLS

h

Ultrarelativistic limits of boosted dilaton black holes

and

Heisenberg-picture approach to the evolution of the scalar fields in an expanding universe

p

Coherence and emergence of classical spacetime

denote depth and the exponent of contact force, and the power-law for the grain velocity is

Quantum electromagnetic fields in the presence of a dielectric microsphere

h^{-1/4({1/3}+1/p)}

Electromagnetic fields in a three-dimensional cavity and in a waveguide with oscillating walls

. Other depth-dependent power-laws for oscillation frequency, wavelength, and period are given by combining above two and the phase velocity power-law