Browsing Physics Research Works by Subject "black holes"
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- ItemFalse Vacuum at the Heart of Black Holes(2001-02) Misner, Charles WIt is proposed that the evaporation of black holes via Hawking radiation may conclude at densities and temperatures no higher than those invoked during the inflationary stage of common cosmological models, thus avoiding the need for quantum gravity or physics at the Planck length in the analysis. The false vacuum associated with cosmological inflation might produce sufficient antigravity to halt the approach to a singularity inside black holes, as matter there is compressed to conditions where a phase transition to false vacuum should occur. This conjecture is supported by a very simplified spherical model of a stationary non-singular black hole containing some false vacuum in a central part of the spacetime well inside the Schwarzschild event horizon.
- ItemInfinite Red-Shifts in General Relativity(Cornell University Press, 1967) Misner, Charles W; Beckedorff, David LThe Oppenheimer-Snyder description of continued gravitational collapse is reformulated as a matching together of two familiar solutions of the Einstein gravitational equations. From one solution, the Friedmann cosmology with zero-pressure matter, one selects the interior of a sphere whose points move on timelike geodesics. From the other solution one selects the exterior of such a sphere in the vacuum Schwarzschild solution. For the expected choice of parameters (sphere circumference, interior density, exterior mass) these can be fit together smoothly enough to satisfy the Einstein equations. The matching conditions are that the first and second fundamental forms at the joining 3-surface agree. The description of this collapsing ball of matter survives its passage through Finkelstein's (1958) smooth unidirectional membrane€ at r=2M and is most conveniently presented using the Kruskal coordinates for the Schwarzschild solution. This project was proposed and designed by Misner (choice of solutions and matching requirements), but the execution and first written presentation were carried out by Beckedorff and provided his Princeton senior thesis in April 1962. ( http://www.physics.umd.edu/grt/cwm/Beckedorff1962.pdf ) In this 1963 presentation Misner emphasizes that the properties of matter at high densities are irrelevant to the question of whether such a collapse can occur for sufficiently massive objects. The detailed computations by Beckedorff are here linked in an appended file.
- ItemMagic Matter, the Computational Æther, and the Miner’s Canary(2001-01) Misner, Charles WSeveral viewpoints are proposed with the aim of promoting further approaches to the numerical integration of Einstein's equations, especially its support of attempts to detect astrophysically significant gravitational waves. Magic Matter suggests that one should instruct computer programs to ignore Einstein's equations inside the horizons of black holes, and to instead to produce computationally convenient metrics there that will not interfere with the correct solution of the equations in the physically observable regions of the simulation. The Computational Æther is the spatial grid of coordinate vertices, conceived as an imaginary substance which spreads itself conveniently over the curved space-time in ways that should simplify the computational effort. The dynamics of magic matter and the computational æther represent instances of Applied Science Fiction, where physical laws inconsistent with our knowledge of nature are used in aspects of simulations that have no observable consequences, but are expected to improve computational efficiency. The Miner’s Canary gives notice in such computations, not that the air in the mine is becoming poisoned, but that some regions of the computational grid probably lie inside apparent horizons so that one may take liberties with the Einstein equations to preserve the life of the computation. Satisfactory implementations of these three ideas are not provided here; rather some first steps toward such are proposed to stimulate further research.