Abstract
HAWKING has shown1 that black holes, treated quantum mechanically, emit black body radiation of temperature T = 10−7 (M⊙/M⊙) K, and hence evaporate—if isolated—on a time scale2 of ∼ 1066 (M/M⊙)3 yr. Energy arguments1,3,4 suggest that a black hole can be assigned the entropy where SH ∼ 40(M/Mp)K is the entropy of a hydrogen cloud from which the black hole is assumed to have formed, Mp is the mass of the proton, and K is Boltzmann's constant. This implies that when a hydrogen cloud of mass 1M⊙ collapses into a black hole, the entropy of the (uncollapsed) galaxy [∼ 1012SH(M⊙) and more] would increase by a factor ∼ 106. In other words: something hardly observable, namely the collapse of one star, would increase the entropy of our cosmic neighbourhood by a large factor. We endeavour to resolve this apparent puzzle.
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References
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Kundt, W., Origin of the Universe, Trends in Physics, (EPS publication, 1973).
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KUNDT, W. Entropy production by black holes. Nature 259, 30–31 (1976). https://doi.org/10.1038/259030a0
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DOI: https://doi.org/10.1038/259030a0
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