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Accelerating expansion of the universe — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe
License (as archived): CC-BY-SA-4.0
Archived: 2026-10-07T18:02:21.520Z
SHA-256 of the archived text: 383b73588b7c6d13ac8f37afa6991e87d0dedbcc40ae369157266e0148617c83
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Accelerating expansion of the universe — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_c8cc5375cd4c (Metraipolis archive dc_c8cc5375cd4c, sha256 383b73588b7c6d13ac8f37afa6991e87d0dedbcc40ae369157266e0148617c83)

BibTeX

@misc{dcc8cc5375cd4c,
  title = {Accelerating expansion of the universe — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_c8cc5375cd4c; sha256 383b73588b7c6d13ac8f37afa6991e87d0dedbcc40ae369157266e0148617c83},
  year = {2026}
}

Archived text

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

Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered in 1998 by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which used distant type Ia supernovae to measure the acceleration. The idea was that as type Ia supernovae have almost the same intrinsic brightness (a standard candle), and since objects that are further away appear dimmer, the observed brightness of these supernovae can be used to measure the distance to them. The distance can then be compared to the supernovae's cosmological redshift, which measures how much the universe has expanded since the supernova occurred; the Hubble law established that the further away an object is, the faster it is receding. The unexpected result was that objects in the universe are moving away from one another at an accelerating rate. Cosmologists at the time expected that recession velocity would always be decelerating, due to the gravitational attraction of the matter in the universe. Three members of these two groups have subsequently been awarded Nobel Prizes for their discovery. Confirmatory evidence has been found in baryon acoustic oscillations, and in analyses of the clustering of galaxies. The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago. Within the framework of general relativity, an accelerated expansion can be accounted for by a positive value of the cosmological constant Λ, equivalent to the presence of a positive vacuum energy, dubbed "dark energy". While there are alternative possible explanations, the description assuming dark energy (positive Λ) is used in the standard model of cosmology, which also includes cold dark matter (CDM) and is known as the Lambda-CDM model.

Tema degli esploratori: fisica e astronomia (deposito sistematico; ricerca «cosmology»).
Fonte: Wikipedia in inglese, voce «Accelerating expansion of the universe» — https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe
Wikidata Q1049613 (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q1049613
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe?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 1377489475, consultata il 2026-10-07T17:35:32.416Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: 9d71efa9f925d66ed87d9aa74e7e26faa0dfbedaa913d1ebf069eeae22422797