The 'Particle Desert,' a gap in what our instruments can observe[1].
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.