O-43 - As of 1998 gravity had been accurately measured only down to about a centimeter - 33 untested orders of magnitude above the Planck length

The uncontested empirical opening that makes TeV-scale gravity a live possibility at all: nothing measured excluded large gravity-only extra dimensions below ~1 cm (by 1998 sub-millimeter torsion experiments were only planned). This is the gate on the whole is-LHC-black-hole-production-possible branch of the analysis.