Observer Systems and the Density Ceiling: A Computed Bound on Coherent Laboratory Mass

This paper computes the largest laboratory mass that can remain coherent for one second under gravitational decoherence estimates, as a concrete form of the observer problem in measurement theory. The mass at which the Diósi–Penrose time falls to one second, for ordinary condensed-matter density, is 1.000e-12 kilograms. A mass of 1e-12 kilograms already decoheres in 9.802e-06 seconds and a mass of 1e-09 kilograms in 9.802e-11 seconds in this estimate. The density ceiling itself is never approached at laboratory densities; the operative limitation on coherent observers and memories is gravitational decoherence scaling, not the ceiling. Wigner-friend scenarios with macroscopic coherent laboratories therefore face a quantified timescale obstacle in this model. The study is simulated and computed from stated assumptions; it is not a measurement.