We propose the Modal-Disconnection Collapse (MDC) hypothesis: coherence between optical modes persists only while the physical coupling structure establishing their modal relation remains intact; removing that structure after photon(s) have passed triggers objective collapse without which-path measurement or decoherence. Standard quantum mechanics deems such post-departure manipulations irrelevant. To our knowledge, no experiment has directly tested this specific intervention. We propose two decisive tests. Experiment A: a single-photon polarization interferometer whose input beam splitter is removed after splitting but before detection. Experiment B: an entangled-photon Bell test where the source region is blocked after emission but before detection, spacelike-separated from detections. MDC predicts vanishing interference visibility (A) and reduction of the Bell-CHSH parameter to separable-state values (B); standard quantum mechanics predicts no change. These experiments close a basic empirical gap, exemplifying a core norm: seemingly obvious claims should remain provisional until directly verified.
Sun-Hyun Youn (Sun,) studied this question.