In his work on the holographic bound, Susskind considered any approximately spherical isolated mass that is not itself a black hole and that fits inside a closed surface of area A.

• 色斯金在全像熵上限的研究中，考虑了任何约略为球形、但本身不是黑洞的孤立质量，同时此质量可以放进面积为A的封闭曲面里。