{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:33:39Z","timestamp":1760240019544,"version":"build-2065373602"},"reference-count":20,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2019,2,16]],"date-time":"2019-02-16T00:00:00Z","timestamp":1550275200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>In this work, we propose a set of conditions such that an ultrarelativistic classical gas can present a photon-like behavior. This is achieved by assigning a zero chemical potential to the ultrarelativistic ideal gas. The resulting behavior is similar to that of a Wien photon gas. It is found to be possible only for gases made of very lightweight particles such as neutrinos, as long as we treat them as classical particles, and it depends on the spin degeneracy factor. This procedure allows establishing an analogy between an evaporating gas and the cavity radiation.<\/jats:p>","DOI":"10.3390\/sym11020249","type":"journal-article","created":{"date-parts":[[2019,2,17]],"date-time":"2019-02-17T22:11:50Z","timestamp":1550441510000},"page":"249","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ultrarelativistic Gas with Zero Chemical Potential"],"prefix":"10.3390","volume":"11","author":[{"given":"Daniel","family":"Mata-Pacheco","sequence":"first","affiliation":[{"name":"Departamento de F\u00edsica, Escuela Superior de F\u00edsica y Matem\u00e1ticas, Instituto Polit\u00e9cnico Nacional, U. P. Adolfo L\u00f3pez Mateos, Zacatenco, M\u00e9xico City C.P. 07738, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7596-2480","authenticated-orcid":false,"given":"Gonzalo","family":"Ares de Parga","sequence":"additional","affiliation":[{"name":"Departamento de F\u00edsica, Escuela Superior de F\u00edsica y Matem\u00e1ticas, Instituto Polit\u00e9cnico Nacional, U. P. Adolfo L\u00f3pez Mateos, Zacatenco, M\u00e9xico City C.P. 07738, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7965-890X","authenticated-orcid":false,"given":"Fernando","family":"Angulo-Brown","sequence":"additional","affiliation":[{"name":"Departamento de F\u00edsica, Escuela Superior de F\u00edsica y Matem\u00e1ticas, Instituto Polit\u00e9cnico Nacional, U. P. 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