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A generalization of this effect is presented with a massive particle whose mass is measured to be in one place with no momentum, while the momentum is measured to be in another place without the mass. The new result applies to any massive particle, independent of its spin or charge. A <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\"><mml:mi>g<\/mml:mi><mml:mi>e<\/mml:mi><mml:mi>d<\/mml:mi><mml:mi>a<\/mml:mi><mml:mi>n<\/mml:mi><mml:mi>k<\/mml:mi><mml:mi>e<\/mml:mi><mml:mi>n<\/mml:mi><\/mml:math> experiment which illustrates this effect is presented using a nested pair of Mach-Zehnder interferometers, but with some of the mirrors and beam splitters moving relative to the laboratory frame. The titular interpretation of this experiment is extremely controversial, and rests on several assumptions, which are discussed in detail. An alternative interpretation using the counterparticle model of Aharonov et al. is also discussed.<\/jats:p>","DOI":"10.22331\/q-2024-11-26-1536","type":"journal-article","created":{"date-parts":[[2024,11,26]],"date-time":"2024-11-26T13:27:53Z","timestamp":1732627673000},"page":"1536","update-policy":"https:\/\/doi.org\/10.22331\/q-crossmark-policy-page","source":"Crossref","is-referenced-by-count":2,"title":["Separating a particle&amp;apos;s mass from its momentum"],"prefix":"10.22331","volume":"8","author":[{"given":"Mordecai","family":"Waegell","sequence":"first","affiliation":[{"name":"Institute for Quantum Studies, Chapman University, 1 University Dr., Orange, CA 92866, USA"}]},{"given":"Jeff","family":"Tollaksen","sequence":"additional","affiliation":[{"name":"Institute for Quantum Studies, Chapman University, 1 University Dr., Orange, CA 92866, USA"},{"name":"Schmid College of Science and Technology, Chapman University, 450 N Center St., Orange, CA 92866, USA"}]},{"given":"Yakir","family":"Aharonov","sequence":"additional","affiliation":[{"name":"Institute for Quantum Studies, Chapman University, 1 University Dr., Orange, CA 92866, USA"},{"name":"Schmid College of Science and Technology, Chapman University, 450 N Center St., Orange, CA 92866, USA"},{"name":"Iyar, The Israeli Institute for Advanced Research, POB 651 Zichron Ya&apos;akov 3095303, Israel"},{"name":"School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel"}]}],"member":"9598","published-online":{"date-parts":[[2024,11,26]]},"reference":[{"key":"0","doi-asserted-by":"publisher","unstructured":"Aharonov Y, Bergmann PG, Lebowitz JL. 1964 Time symmetry in the quantum process of measurement. 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