{"id":482770,"date":"2025-12-31T16:35:26","date_gmt":"2025-12-31T16:35:26","guid":{"rendered":"https:\/\/www.europesays.com\/us\/482770\/"},"modified":"2025-12-31T16:35:26","modified_gmt":"2025-12-31T16:35:26","slug":"a-twist-in-the-tale-are-scientists-wrong-about-dark-energy","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/482770\/","title":{"rendered":"A twist in the tale: are scientists wrong about dark energy?"},"content":{"rendered":"

All major discoveries in cosmology underline the maxim that the universe is not only stranger than we suppose<\/a> but that it is stranger than we can suppose. The latest example of this is a study by researchers at the Yonsei University in South Korea that said the expansion of the universe<\/a> is slowing down.<\/p>\n

The study, published in Notices of the Royal Astronomical Society<\/a> of November 6, is in sharp contrast to the standard model of the universe, called Lambda-Cold Dark Matter<\/a> (LCDM), which speaks of an accelerating universe.<\/p>\n

Mysterious force<\/p>\n

Accepted theory says the universe began about 13.8 billion years ago from a single, infinitely dense point that exploded cataclysmically in a \u2018Big Bang\u2019, leading to the formation of matter, energy, and space.\u00a0As the explosion spread rapidly, it engendered subatomic particles such as protons,\u00a0neutrons, and\u00a0electrons before matter collapsed under gravity to form galaxies, stars and planets.<\/p>\n

While the American astronomer Edwin Hubble confirmed that the universe was expanding in the 1920s, cosmologists conjectured that gravity must have also slowed down the expansion at some point. This is why they were surprised when, in 1998, astronomers who were measuring the distances to faraway galaxies using the light from exploding stars called Type Ia supernovae concluded that 9 billion years after the universe began, its expansion actually gained momentum.<\/p>\n

They figured the impetus came from a mysterious force known as \u2018dark energy\u2019, which makes up about 70% of the cosmos. In 1917, Albert Einstein had proposed that its effects can be represented in equations by the cosmological constant lambda (\u0245).<\/p>\n

Dramatic twist<\/p>\n

For proving that the expansion of the universe had indeed speeded up, three scientists \u2014 Saul Perlmutter, Brian Schmidt, and Adam Riess \u2014 were awarded the 2011 physics Nobel Prize<\/a>. The trio and the teams they led had calculated the distances to Type Ia supernovae by using their apparent brightness as \u201cstandard candles\u201d and measuring the redshift, i.e. the stretching of light due to the expansion of the universe. This helped them determine the speeds at which different parts of the universe were receding from the earth.<\/p>\n

Their data showed that the universe was accelerating as dark energy forced galaxies apart ever faster. An analogy astronomers often use to illustrate this is the way raisins in rising bread dough\u00a0move away from each other. Thus, in the LCDM model of cosmology, gravity binds planets, stars, and galaxies together, while the anti-gravity properties of dark energy push galaxies further away from each other, driving the universe\u2019s expansion.<\/p>\n

The Yonsei University study introduced a dramatic twist to this cosmic tale by suggesting that dark energy may actually be weakening, putting the brakes on the universe\u2019s acceleration.<\/p>\n

\u201cOur study shows that the universe has already entered a phase of decelerated expansion at the present epoch and that dark energy evolves with time much more rapidly than previously thought,\u201d Yonsei University astronomy professor Young-Wook Lee, who led the study, said.<\/p>\n

The findings tie in with similar data from the Dark Energy Spectroscopic Instrument (DESI) in the USA: that Type Ia supernovae may not be the universe\u2019s \u201cstandard candles\u201d after all, since their luminosity could be affected by the age of their parent stars.<\/p>\n

If dark energy density is not constant in time, it flips conventional cosmological wisdom on its head, forcing scientists to look afresh at a universe that may be decelerating, and perhaps eventually contracting before collapsing in on itself in a \u2018Big Crunch\u2019.<\/p>\n

\"\"\u2018Modify, not negate\u2019<\/p>\n

The study has already set off a fierce debate amongst cosmologists, with many doubting if there is enough evidence to revamp the LCDM any time soon, or if at all.<\/p>\n

For instance, in an email to the author, University of Michigan cosmologist Dragan Huterer expressed doubts about dark energy evolving with time. \u201cBut this is really hard to evaluate as we do not have any compelling theoretical models for dark energy. So, from a theoretical point of view, it is not clear,\u201d Prof. Huterer added.\u00a0\u201dFrom the observational\/experimental point of view, the statistical significance of the findings is strong, but not sufficiently strong to claim a discovery. We need to collect and analyse more data to be sure.\u201d<\/p>\n

Brian Schmidt, distinguished professor of astronomy at the Australian National University and one of the three astrophysicists who won the Nobel Prize for their work on dark energy, is sceptical about the study\u2019s consequences for the LCDM.<\/p>\n

\u201cIf validated, these findings would not negate the (standard) model of the cosmos, but would modify it,\u201d Prof. Schmidt wrote in an email. \u201cBasically, instead of a constant [cosmological constant], we would have something that evolves over time.\u201d<\/p>\n

He said he doesn\u2019t think that this would give rise to whole new subfields of astrophysics either.<\/p>\n

\u201cIf true, it will give theorists a new set of clues to understand dark energy. I think it would be contained in the current theoretical cosmology community \u2014 and not (in) a new subfield.\u201d<\/p>\n

Where is the jury?<\/p>\n

Prof Huterer also said that \u201cthese developments would still continue in the realm of data-driven cosmology. And the fact that Type Ia supernovae have some new properties would inform the existing field of Type Ia supernovae astrophysics.\u201d<\/p>\n

Adam Riess, professor of physics and astronomy at the Johns Hopkins University who shared the 2011 Nobel Prize, also said the Yonsei University study doesn\u2019t hold water.<\/p>\n

\u201cThe study claims that Type Ia supernovae become systematically fainter with redshift because their progenitors evolve with cosmic time,\u201d he said. \u201cWe show this is not supported by the data. Modern supernovae analyses already model and marginalise host-related systematics, like stellar mass and star-formation history, and when these are included, there is\u00a0no significant evidence\u00a0for luminosity evolution.\u201d<\/p>\n

According to Prof. Riess, \u201cthe study result arises from a very particular way of slicing the data and from assumptions that aren\u2019t consistent with how supernova cosmology is done today.\u201d<\/p>\n

When the Dark Energy Survey 5 Year dataset sample is analysed with standard methods, he continued, \u201cthe allowed level of evolution is\u00a0an order of magnitude smaller\u00a0than what their model predicts. In short:\u00a0their proposed effect isn\u2019t seen in real data, and current analyses already guard against it.\u201d<\/p>\n

Wherein lies the rub then? According to Prof. Riess, the\u00a0new study makes a leap from host galaxy age to supernova age that is not physically justified. This is something scientists\u00a0have already\u00a0tested and corrected for with much larger datasets.<\/p>\n

\u201cPresent studies already correct for their claimed effect (age) because they correct for galaxy mass, and galaxy mass and age are directly correlated,\u201d he said.<\/p>\n

Taken together, the jury is out on the Yonsei University study. Cosmologists are currently looking to state-of-the-art instruments such as the Vera Rubin Observatory in Chile and NASA\u2019s upcoming Nancy Grace Roman space telescope to throw light on dark energy\u2019s role in the fate of the universe \u2014 whether it will eventually slow down and end in a Big Crunch or continue to expand until it fades away into virtual nothingness.<\/p>\n

Prakash Chandra is a science writer.<\/p>\n","protected":false},"excerpt":{"rendered":"All major discoveries in cosmology underline the maxim that the universe is not only stranger than we suppose…\n","protected":false},"author":3,"featured_media":482771,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25],"tags":[492,159,67,132,68],"class_list":{"0":"post-482770","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science","10":"tag-united-states","11":"tag-unitedstates","12":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115815155234007241","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/482770","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=482770"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/482770\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/482771"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=482770"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=482770"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=482770"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}