Clarifying Feynman’s measurement prescription for testing quantum gravity

Ascertain the exact measurement procedure proposed by Richard Feynman at the 1957 Chapel Hill conference for determining the quantum nature of gravity in his thought experiment involving massive objects in spatial superposition.

Background

The authors revisit Feynman’s famous thought experiment—placing a mass in a spatial superposition to test gravity’s quantum character—and note that modern proposals interpret the decisive signature as entanglement between two masses. However, the historical record does not clearly specify Feynman’s original measurement protocol. Clarifying this prescription matters for interpreting the lineage of current experimental proposals and for assessing which observable genuinely evidences the quantum nature of gravity.