{"id":623252,"date":"2026-01-18T21:53:10","date_gmt":"2026-01-18T20:53:10","guid":{"rendered":"https:\/\/cronologia-universale.it\/1939-16\/"},"modified":"2026-01-18T21:53:11","modified_gmt":"2026-01-18T20:53:11","slug":"1931-21","status":"publish","type":"post","link":"https:\/\/cronologia-universale.it\/en\/1931-21\/","title":{"rendered":"1931"},"content":{"rendered":"<p>Dirac comes to the theoretical conclusion that positrons must exist: all the negative energy states are already occupied but occasionally some holes form which appear to us as positive energy particles (positive mass) identical to the electron, if the electron occupies the hole it is annihilated (the anti-electron, that is, disappears).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Dirac comes to the theoretical conclusion that positrons must exist: all the negative energy states&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[34],"tags":[],"class_list":["post-623252","post","type-post","status-publish","format-standard","hentry","category-e-en"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.0 - 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