2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93564Using various model clocks it has been shown that the time-of-arrival cannot be measured more accurately than 1/E where E is the kinetic energy of a free particle. However, this result has never been proved. In this paper, we show that a violation of the above limitation for the transit-time, implies a violation of the Heisenberg uncertainty relation.Discussion on dwell time added, qualitative proof added, minor modificationsQuantum PhysicsGeneral Relativity and Quantum Cosmologytext