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Title: Can massive superpositions exclude the GRW collapse rate?
Plain: Collapse models modify quantum mechanics so that large objects lose superpositions on their own. The original proposed rate has never been ruled out.
Precise: Continuous spontaneous localization with rate $\lambda$ and length $r_C$. Exclude $\lambda = 1e-16\ \mathrm{s}^{-1}$ at $r_C = 1e-5\ \mathrm{cm}$ (the GRW value of Ghirardi, Rimini and Weber) by interferometric or non-interferometric (heating, noise) tests with massive objects. Answer: yes or no, with the excluded region in the $(\lambda, r_C)$ plane.
Settled by: An interferometry or heating experiment whose excess-decoherence bound lies below lambda = 1e-16 s^-1 at r_C = 1e-5 cm.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: open
Status note: Non-interferometric tests (to 2021) constrain the enhanced Adler rates, and 2025 interference of sodium clusters above 170,000 amu (Pedalino et al., arXiv:2507.21211) tightened interferometric bounds; the GRW point is not reported excluded, which should be checked against the 2025 exclusion plot.
Posed since: 1986