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Chameleon particle — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/Chameleon_particle
License (as archived): CC-BY-SA-4.0
Archived: 2026-10-26T20:04:15.224Z
SHA-256 of the archived text: f631b014f34b4de8f6270cc754aa4b86ec4954eecda4db1c2451274f292930d5
Stable URL of this page: https://metraipolis.com/documento/dc_15efe993a907

How to cite

Chameleon particle — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/Chameleon_particle (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_15efe993a907 (Metraipolis archive dc_15efe993a907, sha256 f631b014f34b4de8f6270cc754aa4b86ec4954eecda4db1c2451274f292930d5)

BibTeX

@misc{dc15efe993a907,
  title = {Chameleon particle — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/Chameleon_particle},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_15efe993a907; sha256 f631b014f34b4de8f6270cc754aa4b86ec4954eecda4db1c2451274f292930d5},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/Chameleon_particle. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

The chameleon is a hypothetical scalar particle that couples to matter more weakly than gravity, postulated as a dark energy candidate. Due to a non-linear self-interaction, it has a variable effective mass which is an increasing function of the ambient energy density—as a result, the range of the force mediated by the particle is predicted to be very small in regions of high density (for example on Earth, where it is less than 1 mm) but much larger in low-density intergalactic regions: out in the cosmos chameleon models permit a range of up to several thousand parsecs. As a result of this variable mass, the hypothetical fifth force mediated by the chameleon is able to evade current constraints on equivalence principle violation derived from terrestrial experiments even if it couples to matter with a strength equal or greater than that of gravity. Although this property would allow the chameleon to drive the currently observed acceleration of the universe's expansion, it also makes it very difficult to test for experimentally. In 2021, physicists suggested that an excess reported at the dark matter detector experiment XENON1T rather than being a dark matter candidate could be a dark energy candidate: particularly, chameleon particles yet in July 2022 a new analysis by XENONnT discarded the excess.

Tema degli esploratori: fisica e astronomia (deposito sistematico; categoria «Physical cosmology»).
Fonte: Wikipedia in inglese, voce «Chameleon particle» — https://en.wikipedia.org/wiki/Chameleon_particle
Wikidata Q1960922: «hypothetical scalar particle» (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q1960922
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/Chameleon_particle?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1316147361, consultata il 2026-10-26T19:48:07.213Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: cb77ff54026c180f4822e95d8c3976a12f40ed360575f0aa64aa231775ff8aa5