By Penrose singularity theorem of 1964 it is known that if there is trapped null surface (and some other conditions) then a singularity must form, in 1983 Schoen and Yau proved how much matter must be crammed into a given volume to create a closed trapped surface, sometimes referred as the Schoen-Yau black hole existence theorem and more recently in 2023 using Gromov's "cube inequality" some tori inequalities used in the results of 1983 have been generalized to cube ones which are more akin to Thorn's circular hoops.