I realize the 2-slit experiment is discussed at the beginning of countless QM books and YouTube videos. I have read the excellent exposition in the first chapter of Feynman & Hibbs, and appreciate that (using Feynman & Hibbs language): A. any determination of which among various alternative paths an electron may take forces these to become exclusive alternatives; while conversely B. in the absence of any determination of which among various alternative paths an electron may take, all alternatives are necessarily interfering alternatives. My question, easily anticipated, concerns "determination", i.e., measurement. I realize that any conjectured way around the statement above will be flawed inasumuch as there must be some action by the "measuring device" which spoils the interference. But identifying this action is not always easy. First example: Suppose you have the usual 2-slit apparatus set-up. Place one clock near each slit and synchronize them. Now allow an electron to pass through one of the two slits and hit a position on a screen. While the electron's mass is very small, nevertheless the clock nearer the slit through which the electron passed will be effected by its gravitational field, and show less elapsed time than the the other clock. Does this destroy the interference pattern?