โ Scribed by George W. Collins II
No coin nor oath required. For personal study only.
During the past decade it has become fashionable to look to the non-intuitive concepts of the General Theory of Relativity to solve almost any problem or explain almost any phenomena. Specifically, black holes have been invoked to provide everything from a power source in galactic nucleii to a description to the explosive event near Tunguska, Siberia in 1908. Although the omnivorous destructive aspects of the classical black hole would appear to make them unlikely candidates as sources of energy, even here we find suggestions that energy could be derived by the squeezing of matter just prior to its disappearance beyond the event horizon. It has even been suggested that we should search for a 'small' black hole, maneuver it near the Earth and obtain energy in this manner by 'feeding it'. Clearly, speculation regarding black holes knows no bounds.
Within the framework of the classical theory a far more elegant and general mechanism for extracting energy has been suggested by Roger Penrose and D. Christodoulou. Although it is classicallyimpossible to tap the matter-energy of a black hole itself, this is not true of the rotational energy which such an object might possess by virtue of its formation. The fracturing of an object in the vicinity of a rotating black hole can, under certain conditions, lead to the loss of a part of the object to the black hole while the remainder acquires energy in considerable excess of the rest energy of the original object. There are, as pointed out by J. Bardeen, W. Press, and S. Teukolsky, some significant 'engineering difficulties' to be encountered in the actual operation of this process. Basically, more energy is required to accelerate the fractured pieces into the necessary orbits than the original piece possesses. Thus for material matter the process appears to be of truly only academic interest. However, this is not the case for photons and it may be true that if the fracturing produces photons, neutrinos or anything exhibiting zero rest mass, that they may participate in the Penrose-Christodoulou scheme and rob a spinning black hole of some of its rotational energy.
However, it is not to the classical theory of general relativity to which I wish to draw attention. Fascinating and important to Astrophysics as these considerations may be, recent developments in the area of quantum gravity promise to be even more far reaching. Stephen Hawking has shown that 'black
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