The 'Particle Desert,' a gap in what our instruments can observe.
It names the enormous unexplored range between the smallest scales we can reach and the tiniest scale physics allows.
The desc puts it at 14 orders of magnitude — a hundred-trillion-fold gap — between what we can observe and the Planck scale.
The engine calls this 'the Firmament made physical' — a concrete wall on what we're able to know.