Description Scale-free 1/f noise appears across electronic devices, biological systems, and geophysical measurements. This paper shows that it is not a system-specific anomaly but the universal structural residue of a projection process that eliminates all coherent degrees of freedom prior to observation. When a bulk-to-boundary projection suppresses phase coherence while preserving long-range correlations, no deterministic observable survives — but correlations remain, and their only admissible form is scale-free. The absence of any privileged scale after projection uniquely selects spectra of the form S(f) ∝ 1/f. Three regimes are distinguished: (i) no projection — bulk information is fully observable; (ii) partial projection — one coherent degree of freedom survives and a dimensionless invariant appears (such as the fine-structure constant α ≈ 1/137); (iii) complete projection — all coherent modes are eliminated and only scale-free noise remains. This places 1/f noise and projection-induced invariants as complementary limits of the same dimensional-reduction mechanism. An application to flicker noise in electronic devices shows that the noise cannot be eliminated by filtering or material improvement — only by a qualitative redesign of the observable that allows at least one coherent mode to survive projection.
Pasquale Camelia (Mon,) studied this question.