I somehow link this ‘shadow’ (by Quantum Theory ;-) of yours to ‘footprint’ of mine.
Shadows appear under lights. Footprints appear under gravity (and in modern slang ‘footprints are remains of our actions/consumption’). No light - no shadow. No gravity (no mass; in vacuum) - no footprint (no life).
Ants leave tiny footprints.
Human leave big, permanent and hazardous footprints.