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**Physics, Astronomy & Cosmology / Re: Do black holes violate the second law of thermodyn**

« **on:**09/10/2006 21:52:32 »

Starting from some theorems proved by Stephen Hawking, Jacob Bekenstein conjectured that the black hole entropy was proportional to the area of its event horizon. Later, Stephen Hawking showed that black holes emit thermal Hawking radiation corresponding to a certain temperature (Hawking temperature). Using some arguments rooted in thermodynamics, Hawking was also able to calculate the entropy that the black hole must carry. The result confirmed Bekenstein's conjecture:

S_{BH} = frac{kA}{4l_{mathrm{P}}^2}

where k is Boltzmann's constant, and l_{mathrm{P}}=sqrt{Ghbar / c^3} is the Planck length. The black hole entropy is proportional to its area A. The fact that the black hole entropy is also the maximal entropy that can be squeezed within a fixed volume was the main observation that led to the holographic principle. The subscript BH either stands for "black hole" or "Bekenstein-Hawking".

from--Wikipedia.

Doc

S_{BH} = frac{kA}{4l_{mathrm{P}}^2}

where k is Boltzmann's constant, and l_{mathrm{P}}=sqrt{Ghbar / c^3} is the Planck length. The black hole entropy is proportional to its area A. The fact that the black hole entropy is also the maximal entropy that can be squeezed within a fixed volume was the main observation that led to the holographic principle. The subscript BH either stands for "black hole" or "Bekenstein-Hawking".

from--Wikipedia.

Doc