分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We compute the Casimir energy of the photon field in a static de Sitter space and find it to be proportional to the size of the horizon, the same form of the holographic dark energy. We suggest to make metamaterials to mimic static de Sitter space in laboratory and measure the predicted Casimir energy. Crown
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We applied the transformation optics to mimic a black hole of Schwarzschild form. Similar properties of photon sphere were also found numerically for the metamaterial black hole. Several reduced versions of the black hole systems were proposed for easier implementations.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We propose a scheme to mimic the expanding cosmos in 1 2 dimensions in laboratory. Furthermore, we develop a general procedure to use nonlinear metamaterials to mimic D-brane and noncommutativity in string theory.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We investigate the Hamiltonian formulation of f(T) gravity and find that there are five degrees of freedom. The six first class constraints corresponding to the local Lorentz transformation in Teleparallel gravity become second class constraints in f(T) gravity, which leads to the appearance of three extra degrees offreedom and the violation of the local Lorentz invariance in f(T) gravity. In general, there are D-1 extra degrees of freedom for f(T) gravity in D dimensions, and this implies that the extra degrees of freedom correspond to one massive vector field or one massless vector field with one scalar field.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We prove that, in general the first law of black hole thermodynamnics, delta Q = T delta S, is violated in f(T) gravity. As a result, it is possible that there exists entropy production, which implies that the black hole thermodynamics can be in non-equilibrium even in the static spacetime. This feature is very different from that of f(R) or that of other higher derivative gravity theories. We find that the violation of first law results from the lack of local Lorentz invariance in f(T) gravity. By investigating two examples, we note that f ''(0) should be negative in order to avoid the naked singularities and superluminal motion of light. When f ''(T) is small, the entropy of black holes in f(T) gravity is approximatively equal to (f'(T))/(4)A
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-08
摘要: We study the P - V criticality and phase transition in the extended phase space of charged Gauss-Bonnet black holes in anti-de Sitter space, where the cosmological constant. appears as a dynamical pressure of the system and its conjugate quantity is the thermodynamic volume of the black holes. The black holes can have a Ricci flat (k - 0), spherical (k = 1), or hyperbolic (k = -1) horizon. We find that for the Ricci flat and hyperbolic Gauss-Bonnet black holes, no P - V criticality and phase transition appear, while for the black holes with a. spherical horizon, even when the charge of the black hole is absent, the P - V criticality and the small black hole/large black hole phase transition will appear, but it happens only in d = 5 dimensions; when the charge does not vanish, the P - V criticality and the small black hole/large phase transition always appear in d = 5 dimensions; in the case of d >= 6, to have the P - V criticality and the small black hole/large black hole phase transition, there exists an upper bound for the parameter b = (alpha) over tilde vertical bar Q vertical bar(-2/(d-3)), where (alpha) over tilde is the Gauss-Bonnet coefficient and Q is the charge of the black hole. We calculate the critical exponents at the critical point and find that for all cases, they are the same as those in the van der Waals liquid-gas system.