Related papers: Life under a black sun
<PART1> According to the standard LCDM model, the matter and dark energy densities (rho_m and rho_DE) are only comparable for a brief time. We address the cosmic coincidence problem under LCDM and generalized dark energy models by…
We propose a one-shot mechanism for high-energy cosmic ray generation by a neutron star falling into a black hole surrounded by low density plasma. The function of the black hole in this scenario is to accelerate the star to a speed…
We provide a simple way for calculating the entropy of a Schwarzschild black hole from the entropy of its Hawking radiation. To this end, we show that if a thermodynamic system loses its energy only through the black body radiation, its…
We estimate the energy release of black hole formation to the intra-cluster medium of the Coma cluster and find that this is comparable to the present day energy content. Therefore an energetic and maybe hydrostatic influence is possible.…
We investigate the energy distribution of a black hole in various spacetimes as reckoned by a distant observer using the quasi-local energy approach. In each case the horizon mass of a black hole: neutral, charged or rotating, is found to…
The circumstellar habitable zone and its various refinements serves as a useful entry point for discussing the potential for a planet to generate and sustain life. But little attention is paid to the quality of available energy in the form…
The simplest possible equation for Hawking radiation, and other black hole radiated power is derived in terms of black hole density. Black hole density also leads to the simplest possible model of a gas of elementary constituents confined…
We study the Hawking radiation of (4+n)-dimensional Schwarzschild black hole imbedded in the space-time with positive cosmological constant. The greybody and energy emission rates of scalars, fermions, bosons, and gravitons are calculated…
Radiation of conserved charges carried by a black hole is a rare process, whose probability is suppressed by the change in the entropy between the initial and final states. This universal result provides insight into the black hole's…
Curiously, our Universe was born in a low entropy state, with abundant free energy to power stars and life. The form that this free energy takes is usually thought to be gravitational: the Universe is almost perfectly smooth, and so can…
If two particles collide in the vicinity of a black hole horizon, their center of mass energy is practically unlimited, so another black hole with a large mass and thus entropy can be created. The resulting black hole can then merge with…
We consider test planet and photon orbits of the third kind inside a black hole, which are stable, periodic and neither come out of the black hole nor terminate at the singularity. Interiors of supermassive black holes may be inhabited by…
The total energy emitted by the growth of massive black holes is large and can be 10-50 per cent of that emitted by stars in the universe. I show how the X-ray Background provides a good measure of this energy and also why most accretion…
When a star collapses to form a black hole, its entropy increases considerably, for a solar mass black hole, there is a factor of 1019 increase in entropy. This corresponds to a tremendous loss of information as only the total mass, angular…
A new scenario for extracting energy from a Kerr black hole is proposed. With magnetic field lines connecting plasma particles inside the ergosphere with remote loads, the frame dragging twists the field lines so that energy and angular…
In the science fiction film $Interstellar$, a band of intrepid astronauts sets out to explore a system of planets orbiting a supermassive black hole, searching for a world that may be conducive to hosting human life. While the film…
A long march of fifty years of successive theoretical progress and new physics discovered using observations of gamma-ray bursts, has finally led to the formulation of an efficient mechanism able to extract the rotational energy of a Kerr…
Taking seriously the interpretation of black hole entropy as the logarithm of the number of microstates, we argue that thermal gravitons may undergo a phase transition to a kind of black hole condensate. The phase transition proceeds via…
Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb.…
If a supermassive black hole has some material orbiting around it at close to its innermost stable circular orbit (ISCO), then, when it plunges into a second supermassive black hole, the orbiting material has a velocity dispersion of order…