2014/12/31 by Ali Masoumi, Samir D. Mathur · 1 citation
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Bounded function #Cosmology and Gravitation Theories #Covariant transformation #Entropy (arrow of time) #Galaxies: Formation, Evolution, Phenomena #Joint quantum entropy #Mathematical analysis #Mathematical physics #Mathematics #Physics #Quantum #Quantum mechanics #Theoretical physics #Upper and lower bounds #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.91.084058
published as Phys. Rev. D 91, 084058 (2015) · 21 pages, 10 figures, More general derivation given, comments about viscosity effects added
arxiv created 2015/01/24 · openalex publication_date 2015/04/29 · arxiv updated 2015/05/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Several arguments suggest that the entropy density at high energy density \ensuremathρ should be given by the expression s=K√\ensuremathρ/G, where K is a constant of order unity. On the other hand the covariant entropy bound requires that the entropy on a light sheet be bounded by A/4G, where A is the area of the boundary of the sheet. We find that in a suitably chosen cosmological geometry, the above expression for s violates the covariant entropy bound. We consider different possible explanations for this fact, in particular, the possibility that entropy bounds should be defined in terms of volumes of regions rather than areas of surfaces.