This quantity characteristically scales logarithmically with evolution time in systems displaying many-body localization. This quantity evolves over time to form an inverted V shape on the Page curve. For a tripartite quantum (10[1])system, this quantity obeys strong subadditivity. (10[1])For pure states, (10[1])the distillable (10[1])and squashed (10[1])entanglements reduce to this quantity. (10[1])For a system with density matrix rho, this quantity equals (10[2])the negative trace (10[1])of rho (10[4])times (10[3])log rho. (10[3])By (10[1])the (10[1])Bekenstein–Hawking (10[3])formula, (10[2])the area of a black hole is proportional (10[4])to its value of this quantity. (10[4]-5[1])In classical (10[1]-5[1])information theory, (10[1]-5[1])this (10[1])quantity expresses the (10[1])absence (10[3])of information about (10[1])a system (10[4]-5[1])and is (10[1])measured in shannons. (10[3])For (10[2])10 (10[1])points, (10[5])name (10[1])this (10[1])quantity that increases in accordance (10[2])with the second (10[1])law (10[1])of thermodynamics. (10[3]) (10[11]0[1])■END■