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Doing so would show whether a quantum source pulls on a probe through its average position or through each branch separately.","posed_since":"","precise":"Prepare a source mass $M$ in a spatial superposition of separation $\\Delta x$ and measure a probe's response that distinguishes a field sourced by the expectation value $\\langle T_{00}\\rangle$ (Moller-Rosenfeld semiclassical gravity) from a branch-correlated field, at force scale $\\sim G M m_{\\mathrm{probe}} \\Delta x / d^3$. Required: source masses small enough to superpose ($M <\\sim 10^{-11}\\,\\mathrm{g}$) and probe force sensitivity at that scale.","problem_ref":"18a481167193f5a6b3195ce0b7a7bf7224e59db1d998673fe38ffafdb1afb07d","references":"","settled_by":"A probe measurement whose outcome statistics are correlated with the source branch (quantum) or follow the mean field (semiclassical).","status_note":"Page and Geilker (1981) excluded the simplest mean-field model using a classically randomized source; no experiment has used a source in a coherent spatial superposition.","title":"Measure the gravity of a mass that is in 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