Evidence Mounts that Universe's Dark Energy is Changing over Time
New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant, as long hypothesized.
The findings announced on Wednesday are part of a years-long study of the history of the cosmos, focusing upon dark energy. The researchers analyzed three years of observations by the Dark Energy Spectroscopic Instrument, or DESI, at Kitt Peak National Observatory in Arizona.
"The DESI results tantalizingly hint at an evolving dark energy," said Arjun Dey, an astrophysicist at the US National Science Foundation's NOIRLab and the NOIRLab project scientist for DESI.
The new analysis used data from DESI's first three years of observations of almost 15 million galaxies and quasars, which are extremely bright galactic cores where a supermassive black hole hungrily consumes surrounding material, Reuters reported.
This analysis, combined with other astrophysical data, offers mounting evidence that the impact of dark energy may be weakening over time and that the standard model of how the universe works may need to be revised, the researchers said.
Those other measurements include the light left over from the dawn of the universe, exploding stars called supernovae and the manner in which light from distant galaxies is warped by gravity.
"The new findings, both from DESI and from a number of other experiments, now suggest that whatever is causing the universal expansion may be decaying - that is, decreasing in strength," Dey said. "This once again changes our fundamental understanding of nature, and in particular our understanding of the future of our universe. Will the expansion continue forever, or will the acceleration slow, stop and turn into a deceleration?"
Out of the water and onto the recovery vessel wow we got a cute little pot of dolphins it wasn't just one or two now here on your screen we can see dolphins
The Big Bang event roughly 13.8 billion years ago initiated the universe, and it has been expanding ever since. Scientists in 1998 disclosed that this expansion was actually accelerating, with dark energy as the hypothesized reason. The physical nature of dark energy is presently unknown.
"DESI data tells us about how the size of the universe has grown over time. We can relate the rate at which it is growing directly to the strength - or energy density - of dark energy at a given time, since dark energy is what causes that growth rate to accelerate," said University of Pittsburgh astrophysicist Jeff Newman, another of the researchers.
The universe's contents include ordinary matter - stars, planets, gas, dust and all the familiar stuff on Earth - as well as dark matter and dark energy.
Ordinary matter represents perhaps 5% of the contents. Dark matter, which is known through its gravitational influences on galaxies and stars, may make up about 27%. Dark energy may make up about 68%.
"Dark energy is definitely one of the most puzzling and mysterious components of the universe. We don't yet know what it is, but we can detect its clear effect on the expansion of the universe," Dey said.
"All the matter in the universe has gravity which should be slowing down the rate of expansion. Instead, we observe that the universal expansion is accelerating, and we attribute this unexpected behavior to dark energy, a component of the universe which exerts a pressure to push things apart - kind of like a negative gravity," Dey added.
The new findings were presented at the American Physical Society's Global Physics Summit in Anaheim, California.
"Our findings in DESI that the dark energy is evolving in time and is not the cosmological constant is probably the most important result about cosmic acceleration since its discovery in 1998 that led to the Nobel Prize in physics in 2011," said cosmologist Mustapha Ishak of the University of Texas at Dallas and co-chair of the working group that analyzed the DESI data.
"The new and unexpected result is likely to change the future of cosmology and our understanding of its standard model," Ishak added.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Asharq Al-Awsat
05-05-2025
- Asharq Al-Awsat
EU's Von der Leyen Announces 500 Mln Euro Package to Lure Top Researchers to Europe
European Commission President Ursula von der Leyen announced on Monday a 500 million euros ($566.6 million) incentive package to boost European science research, as Europe hopes to lure top US scientists disgruntled with President Donald Trump. "Science is an investment – and we need to offer the right incentives. This is why I can announce that we will put forward a new 500 million euros package for 2025-2027 to make Europe a magnet for researchers," she said at a speech in Paris alongside French President Emmanuel Macron. "We are choosing to put research and innovation, science and technology, at the heart of our economy. We are choosing to be the continent where universities are pillars of our societies and our way of life," she added. She also said she wanted EU-member states to invest 3% of gross domestic product in research and development by 2030, Reuters reported. Last month, Macron and Von der Leyen said they would be looking to invite scientists and researchers from the world over to Europe, at a time when Trump's administration is threatening to cut federal funding for Harvard and other US universities. In April, France also launched the "Choose France for Science" platform, operated by the French National Research Agency (ANR), which enables universities, schools, and research organizations to apply for co-funding from the government to host researchers.
Leaders
01-05-2025
- Leaders
Round vs. Flat: Defying Misconceptions on the Earth's Shape
By: Dr. Mohamed Farag Recently, a controversial question has gone viral across social media platforms: Is the Earth round or flat? Despite the overwhelming evidence and numerous devices proving the Earth is a sphere, including space missions and satellites, some groups claim that the Earth is flat and encircled by an ice wall. Those groups call themselves 'The Flat Earth Society.' Round or Flat? More than 2,200 years ago, Eratosthenes, a Greek astronomer, geographer, mathematician, and poet, proved the Earth's spherical nature. So did Al-Biruni, a Muslim astronomer, mathematician, historian, and geographer. Using the tools available at the time, both scholars calculated the circumference of the Earth with remarkable precision. A depiction of flat Earth Another compelling piece of evidence lies in the shape of other celestial bodies. If you looked through a telescope on a clear night, you would see Jupiter and Saturn appearing as spheres. The Earth is no different. The Age of Earth Scientifically speaking, the age of Earth is estimated to be about 4.5 billion years. Scientists calculated it through geological studies and radiometric dating (the analysis of radioactive elements found in old rocks and minerals). Atoms in radioactive elements decay into lighter elements with lower atomic mass. Each radioactive element needs a certain amount of time for half of its atoms to decay. This is called 'half-life.' By measuring the ratio of the decay products to the ratio of the original element, we can determine how long that sample has been in this location. This method is used to calculate the age of the remains of living organisms and other substances. How the Earth Formed Initially, the universe was void, then it pulsed with matter and energy in what is known as the 'Big Bang.' Matter dispersed across the cosmos, eventually forming hydrogen atoms after a certain period. Following this, hydrogen accumulated in nebulae. Hydrogen nuclei began to fuse in stars, creating radiant stars pulsing with energy. After the consumption of hydrogen in some of those stars, they evolved into red giants or supergiants, depending on their mass. Some of those stars explode, scattering atoms heavier than hydrogen into space. Atoms heavier than iron are formed in neutron stars. Earth Dust particles accumulate in a specific location, forming either a planet or a moon that orbits a planet. Given that gravity operates in all directions, these planets or celestial bodies take a spherical shape. These theories form the basis for the study of the observable universe. They are substantiated by mathematical models and observations. Since the Earth is no different from these planets and stars, it is consequently spherical. Real-world Evidence When you lie down on a beach by the sea or ocean, you will notice ships disappear hull down over the horizon, with the upper parts vanishing last. This is because the Earth's curvature blocks the line of sight to the lower part of the ship. Furthermore, there are plenty of phenomena that confirm that the Earth is a sphere, such as lunar and solar eclipses during which we can simply observe the Earth's shadow on the Moon, as well as the Moon blocking sunlight. Moreover, the change of star positions with the change of geographical location provides another compelling piece of evidence. Similarly, the star constellations visible in the Northern Hemisphere are different from those seen in the Southern Hemisphere. About the author: Dr. Mohamed Farag is an associate professor of physics at Al-Azhar University. Short link : Post Views: 1
Asharq Al-Awsat
27-04-2025
- Asharq Al-Awsat
Oldest-known Ant Preserved in 113 Million-year-old Brazilian Fossil
Scientists have identified the fossilized remains of the oldest-known ant - a winged insect with fearsome scythe-like jaws that lived about 113 million years ago during the age of dinosaurs and was preserved in limestone unearthed in northeastern Brazil. The species, called Vulcanidris cratensis, is part of a lineage called hell ants - named for their demonic-looking jaws - that prospered in a wide geographical range during the Cretaceous Period but have no descendants alive today, Reuters reported. A previously discovered Cretaceous hell ant was named Haidomyrmex in honor of Hades, the ancient Greek god of the underworld. A medium-sized ant about a half-inch (1.35 cm) long, Vulcanidris possessed highly specialized jaws that would have enabled it to pin down or impale prey. Like some ants alive today, it had wings and appears to have been a capable flier. It also had a well-developed stinger like a wasp. "It would probably be confused with a wasp by an untrained eye," said entomologist Anderson Lepeco of the Museum of Zoology of the University of São Paulo, lead author of the study published this week in the journal Current Biology. "They probably used their mandibles (mouthparts) to handle their prey in a specific way," Lepeco said. Its mandibles moved up and down and not side to side, as they do in today's ants. "Currently, many odd mandible shapes can be found in ants, but they usually articulate horizontally," Lepeco said. This ant is roughly 13 million years older than the previous oldest-known ants, specimens found in France and Myanmar that were preserved in amber, which is fossilized tree sap. The Vulcanidris anatomy is remarkably well preserved in the limestone, which was excavated decades ago in the Crato geological formation in the Brazilian state of Ceará, probably in the 1980s or 1990s, according to Lepeco. It was held in a private collection before being donated to the São Paulo museum about five years ago. "I was looking for wasps among the fossils of the collection and was shocked when I recognized this one as a close relative of a hell ant previously described from Burmese amber," Lepeco said, referring to the fossil from Myanmar. The specialized nature of the Vulcanidris anatomy and the fact that two hell ants lived so far from each other during this part of the Cretaceous suggest that ants as a group emerged many millions of years before this newly identified species existed. "According to molecular estimates, ants originated between 168 million and 120 million years ago. This new finding supports an earlier age within these limits," Lepeco said. Ants are believed to have evolved from a form of wasp. Their closest living relatives are wasps and bees. Vulcanidris inhabited an ecosystem teeming with life. Fossils from the region show that Vulcanidris lived alongside other insects, spiders, millipedes, centipedes, various crustaceans, turtles, crocodilians, flying reptiles called pterosaurs, birds and dinosaurs including the feathered meat-eater Ubirajara. The ant's predators may have included frogs, birds, spiders and larger insects. Ants have colonized almost everywhere on Earth, and research published in 2022 estimated that their total population is 20 quadrillion globally. That dwarfs the human population of about 8 billion. "They are one of the most abundant groups in most environments on Earth," Lepeco said. "They play many roles where they occur, such as predation and herbivory, controlling populations of other organisms. They also have intrinsic relationships with specific plants and insects, protecting them from other animals. Subterranean and litter ants help in soil health, and they may also act as decomposers, feeding on dead organisms," Lepeco said.
