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arXiv · hep-th/9905177

A Covariant Entropy Conjecture

Raphael Bousso
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Abstract

We conjecture the following entropy bound to be valid in all space-times admitted by Einstein's equation: Let A be the area of any two-dimensional surface. Let L be a hypersurface generated by surface-orthogonal null geodesics with non-positive expansion. Let S be the entropy on L. Then S does not exceed A/4. We present evidence that the bound can be saturated, but not exceeded, in cosmological solutions and in the interior of black holes. For systems with limited self-gravity it reduces to Bekenstein's bound. Because the conjecture is manifestly time reversal invariant, its origin cannot be thermodynamic, but must be statistical. Thus it places a fundamental limit on the number of degrees of freedom in nature.

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Raphael Bousso. 1999-06-24. A Covariant Entropy Conjecture. https://doi.org/10.1088/1126-6708%2F1999%2F07%2F004

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