Abstract
Bousso has conjectured that in any spacetime satisfying Einstein’s equation and satisfying the dominant energy condition, the “entropy flux” S through any null hypersurface L generated by geodesics with non-positive expansion starting from some spacelike 2 surface of area A must satisfy This conjecture reformulates earlier conjectured entropy bounds of Bekenstein and also of Fischler and Susskind, and can be interpreted as a statement of the so-called holographic principle. We show that Bousso’s entropy bound can be derived from either of two sets of hypotheses. The first set of hypotheses is (i) associated with each null surface L in spacetime there is an entropy flux 4-vector whose integral over L is the entropy flux through L, and (ii) along each null geodesic generator of L, we have where is the stress-energy tensor, is an affine parameter, and is the value of affine parameter at the endpoint of the geodesic. The second (purely local) set of hypotheses is (i) there exists an absolute entropy flux 4-vector such that the entropy flux through any null surface L is the integral of over L, and (ii) this entropy flux 4-vector obeys the pointwise inequalities and for any null vector Under the first set of hypotheses, we also show that a stronger entropy bound can be derived, which directly implies the generalized second law of thermodynamics.
- Received 10 August 1999
DOI:https://doi.org/10.1103/PhysRevD.62.084035
©2000 American Physical Society