Uudet pimeän energian havainnot

[ispa]

FaceBookissa [uurl=https://www.facebook.com/secretsofuniverse]The Secrets Of The Universe[/url] julkaisi jutun pimeän energian uusista havainnoista. Olen tähtitieteessä melkoinen aloittelija. Kävin kosmologia-kurssin ja esitin siellä ajatuksen: Pimeä energia ja pimeä aine voi olla jotain, mitä emme vielä tiedä. Esimerkiksi uusi voimatyyppi kuten on gravitaatio. Jne. Kurssin pitäjä kommentoi sitä ajatusta. Pidin siitä, että ajatus huomioitiin. Tämä ei ole vasta-argumentti nykyisille käsityksille. Vaan ajatusten herättäjiä.

Tässä on näistä uusista havainnoista. FaceBookissa esitetyt asiat eivät välttämättä ole tiedettä.

The latest dark energy finding shakes Einstein's theory of the universe! 👇🏻
For over two decades, dark energy—the mysterious force pushing the universe apart—has been assumed to be constant, a steady backdrop fueling cosmic acceleration. But now, new data from two major collaborations suggests that this may not be the case. According to recent findings presented at the Global Physics Summit in March 2025, dark energy might not be constant after all—it may be weakening, shaking the very core of modern cosmology.

The Dark Energy Spectroscopic Instrument (DESI) and the Dark Energy Survey (DES) have both reported results that point to a slow-down in the strength of dark energy—a potential sign that the universe's accelerated expansion is changing course. This development directly challenges the Lambda-CDM model, the current standard model of cosmology, which assumes dark energy is a fixed "cosmological constant" as proposed by Einstein.
Using three years of data, the DESI team mapped the positions of over 15 million galaxies, measuring how matter has clustered across vast cosmic distances. These patterns, remnants of sound waves from the early universe, act like "cosmic fossils" that help trace how the expansion of the universe has evolved.

When DESI's data was combined with supernova observations and measurements from the cosmic microwave background (CMB), researchers found something surprising: the data shows a 4.2-sigma tension with the standard model—a statistical measure that suggests there's only a 1 in 30,000 chance the Lambda-CDM model is still correct.

The analysis points to a strange behavior in dark energy's strength. For billions of years, it intensified, accelerating the universe's expansion, but then began weakening around 6 billion years ago. This shift, known as "phantom crossing," suggests a transition in how dark energy behaves over time.

Meanwhile, the DES collaboration, which surveyed 12% of the sky, found a 3.2-sigma tension with the standard model—independently supporting DESI's conclusions. Their data, combining galaxy clustering, supernova light, and CMB measurements, also hints that dark energy may be dynamic, not constant.
If dark energy really is fading, the implications are massive. The fate of the universe itself could change. The widely accepted idea that the universe will continue expanding forever into a cold, dark "heat death" may be replaced by new possibilities—such as a slow-down in expansion, a Big Crunch (where the universe collapses in on itself), or a new phase of cosmic evolution.

[mistral]

Olisi hienoa jos kosmologia yksinkertaistuisi, esim pimeää energiaa ei tarvittaisi vaan luonnollisempi selitys löytyisi.

[Eusa]

Olisi hienoa jos kosmologia yksinkertaistuisi, esim pimeää energiaa ei tarvittaisi vaan luonnollisempi selitys löytyisi.

Luonnollinen selitys löytyy entropiasta, mutta vaikka se periaatteena on yksinkertainen, entropiatiheys on vakio ja kaikkeus kokonaisentropian laajuinen, simulaatiot ovat helposti melko monimutkaisia.

[velihopea]

Nyt luin ispan siteeraamaa tekstiä, vaikkakin se on facebookiin kautta saatua, ja koetin ymmärtää mitä siinä siis sanotaan. Merkkasin joitakin kohtia "(***n)" tagilla, joita avaan alempana.

The latest dark energy finding shakes Einstein's theory of the universe! 👇🏻
For over two decades, dark energy—the mysterious force pushing the universe apart—has been assumed to be constant (***1), a steady backdrop fueling cosmic acceleration. But now, new data from two major collaborations suggests that this may not be the case. According to recent findings presented at the Global Physics Summit in March 2025 (***2), dark energy might not be constant after all—it may be weakening (***3), shaking the very core of modern cosmology.

The Dark Energy Spectroscopic Instrument (DESI) and the Dark Energy Survey (DES) have both reported results that point to a slow-down in the strength of dark energy—a potential sign that the universe's accelerated expansion is changing course (***4). This development directly challenges the Lambda-CDM model, the current standard model of cosmology, which assumes dark energy is a fixed "cosmological constant" as proposed by Einstein.
Using three years of data, the DESI team mapped the positions of over 15 million galaxies, measuring how matter has clustered across vast cosmic distances. These patterns, remnants of sound waves from the early universe, act like "cosmic fossils" that help trace how the expansion of the universe has evolved.

When DESI's data was combined with supernova observations and measurements from the cosmic microwave background (CMB), researchers found something surprising: the data shows a 4.2-sigma (***5) tension with the standard model—a statistical measure that suggests there's only a 1 in 30,000 chance the Lambda-CDM model is still correct.

The analysis points to a strange behavior in dark energy's strength. For billions of years, it intensified, accelerating the universe's expansion, but then began weakening around 6 billion years ago. This shift, known as "phantom crossing," (***6) suggests a transition in how dark energy behaves over time.

Meanwhile, the DES collaboration, which surveyed 12% of the sky, found a 3.2-sigma tension with the standard model—independently supporting DESI's conclusions. Their data, combining galaxy clustering, supernova light, and CMB measurements, also hints that dark energy may be dynamic, not constant.
If dark energy really is fading, the implications are massive. The fate of the universe itself could change. The widely accepted idea that the universe will continue expanding forever into a cold, dark "heat death" may be replaced by new possibilities—such as a slow-down in expansion, a Big Crunch (where the universe collapses in on itself), or a new phase of cosmic evolution.

(***1): Mikä ihmeen vakio? Tarkoitataan kosmologista vakiota, jolla AI tiesi kaavan "lambda = ~1.1 x 10^(-52) x 1/m2)". Johon totean, että onpa siinä kahdella merkitsevällä numerolla asetettu likiarvo ison asian vartijaksi.

(***2) On APS:n (American Physical Society) järjestämä konferenssi Anaheim/CA:ssa 16-21.3.2025. Kehuvat olevansa maailman suurin fysiikan (useita osa-alueita) konferenssi, ~15.000 fyysikkoa ja opiskelijaa paikalla tai virtuaalisesti. Siis muskeleita on, ehkä tiedeuskottavuuttakin.

(***3) Että avaruus ei laajenisikaan kiihtyvästi! Jos noin on, harmi kun tuli annettua ne Nobelit. Mutta tekevälle sattuu.

(***4) Aiheessa "Tutkimusartikkeli: pimeää energiaa ei ehkä olekkaan" puhuttiin samansuuntaista asiaa ja viitattiin DES5yr projektiin.

(***5) Havainnon (tai päättelyn?) varmuustaso 4.2 ei riitä fyysikoille. Sellaisia pitää olla useita riippumattomia ennen kuin vallitseva käsitys alkaa kaatua tai täydentyä. Tai pitää saada 5-varmuustason havainto (kuten higsin hiukkanen).

(***6) "phantom crossing" on joku pimeän energian tilayhtälön parametri: -1 tai alle tai yli, mikä aiheuttaa eriasteista laajenemista.

Aiheessa "Osa2: Epäselvyys..." muutamaan kertaan mainittu DU-malli ulottuu myös taivaan mekaniikkaan. Siellä DU pärjää ilman pimeää energiaa.

[ispa]

En ole enkä ole pystynyt syvällisesti miettiä noita asioita. Muistan kuitenkin, että yksi suure, jota on pidetty vakiona, ei olisikaan vakio vaan muuttuu koko ajan. Sitäkään en tiedä, onko se koko ajan kasvava / vähenevä vai onko sillä aaltomuoto. Tutkittavaa riittää. Ja se on oikeastaan hyväksi ihmiselle. Aivot saavat voimistelua.