Entropy and area
Abstract
The groundstate density matrix for a massless free field is traced over the degrees of freedom residing inside an imaginary sphere; the resulting entropy is shown to be proportional to the area (and not the volume) of the sphere. Possible connections with the physics of black holes are discussed.
 Publication:

Physical Review Letters
 Pub Date:
 August 1993
 DOI:
 10.1103/PhysRevLett.71.666
 arXiv:
 arXiv:hepth/9303048
 Bibcode:
 1993PhRvL..71..666S
 Keywords:

 05.30.d;
 11.10.z;
 97.60.Lf;
 Quantum statistical mechanics;
 Field theory;
 Black holes;
 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Lattice
 EPrint:
 10 pages, in Plain TeX with one figure included, LBL33754. (Revised version adds an important reference and corrects minor typos.)