Black hole induced false vacuum decay from first principles

We provide a method to calculate the rate of false vacuum decay induced by a black hole. The method uses complex tunneling solutions and consistently takes into account the structure of different quantum vacua in the black hole metric via boundary conditions. The latter are connected to the asymptotic behavior of the time-ordered Green’s function in the corresponding vacua. We illustrate the technique on a two-dimensional toy model of a scalar field with inverted Liouville potential in an external background of a dilaton black hole. We analytically derive the exponential suppression of tunneling from the Boulware, Hartle-Hawking and Unruh vacua and show that they are parametrically different. The Unruh vacuum decay rate is exponentially smaller than the decay rate of the Hartle-Hawking state, though both rates become unsuppressed at high enough black hole temperature. We interpret the vanishing suppression of the Unruh vacuum decay at high temperature as an artifact of the two-dimensional model and discuss why this result can be modified in the realistic case of black holes in four dimensions.

Black Holes as Markers of Dimensionality

Black hole temperature as a function of its Planck length diameter multiple is derived from black hole surface gravity and Hawking temperature. It is conjectured that this multiple corresponds to dimensionality of the graph of nature with d = 1/2pi describing primordial Big Bang singularity. A black hole interacts with the environment and observable black holes have uniquely defined Delaunay triangulations with a natural number of spherical triangles having Planck areas (bits), where a Planck triangle is active and has gravitational potential of -c^2 if all its vertices have black hole gravitational potential of -c^2/2 and is inactive otherwise. Temporary distribution of active triangles on an event horizon tends to maximize Shannon entropy. Black hole blackbody radiation, informational capacity fluctuations, and quantum statistics are discussed. On the basis of the latter, wavelength bounds for BE, MB, and FD statistics are derived as a function of a diameter. A similarity of the logistic function and black hole FD statistics leads to the BE logistic function and map. This outlines the program for research of other nature phenomena that emit perfect blackbody radiation, such as neutron stars and white dwarfs.

Thermal image and phase transitions of charged AdS black holes using shadow analysis

We investigate the relations between the black hole shadow and charged AdS black hole critical behavior in the extended phase space. Using the thermo-shadow formalism built in Ref. 1, we reveal that the shadow radius can be considered as an efficient tool to study thermodynamical black hole systems. Based on such arguments, we build a thermal profile by varying the RN–AdS black hole temperature on the shadow silhouette. Among others, the Van der Waals-like phase transition takes place. This could open a new window on the thermal picture of black holes and the corresponding thermodynamics from the observational point of view.

Holographic complexity for disentangled states

We consider the maximal volume and the action, which are conjectured to be gravity duals of the complexity, in the black hole geometries with end-of-the-world branes. These geometries are duals of boundary states in conformal field theories which have small real space entanglement. When we raise the black hole temperature while keeping the cutoff radius, black hole horizons or end-of-the-world branes come in contact with the cutoff surface. In this limit, holographic entanglement entropy reduces to zero. We study the behavior of the volume and the action, and find that the volume reduces to zero in this limit. The behavior of the action depends on their regularization. We study the implication of these results to the reference state of the holographic complexity both in the complexity = volume or the complexity = action conjectures.

Embedding into flat spacetime and black hole thermodynamics

It is known that static and spherically symmetric black hole solutions of general relativity in different spacetimes can be embedded into higher-dimensional flat spacetime. Given this result, we have explored the thermodynamic nature of black holes á la its embedding into flat spacetime. In particular, we have explicitly demonstrated that black hole temperature can indeed be determined starting from the embedding and hence mapping of the static observers in black hole spacetime to Rindler observers in flat spacetime. Furthermore, by considering the dynamics of a scalar field in the flat spacetime, it is indeed possible to arrive at the area scaling law for black hole entropy. Thus, by using the flat spacetime field theory, one can indeed provide a thermodynamic description of black holes. Implications are also discussed.

Is there an upper bound on the size of a black hole?

According to the third law of Thermodynamics, it takes an infinite number of steps for any object, including black holes, to reach zero temperature. For any physical system, the process of cooling to absolute zero corresponds to erasing information or generating pure states. In contrast with the ordinary matter, the black hole temperature can be lowered only by adding matter–energy into it. However, it is impossible to remove the statistical fluctuations of the infalling matter–energy. The fluctuations lead to the fact that the black holes have a finite lower temperature and, hence, an upper bound on the horizon radius. We make an estimate of the upper bound for the horizon radius which is curiously comparable to Hubble horizon. We compare this bound with known results and discuss its implications.