Evidence mounts that universe's dark energy is changing over time
By Will Dunham
WASHINGTON (Reuters) - 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 U.S. 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.
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?"
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
Yahoo
19 minutes ago
- Yahoo
China is only 3-6 months behind US in AI, Trump official says
WASHINGTON (Reuters) -China is three to six months behind the United States in artificial intelligence, White house AI and crypto czar David Sacks said Tuesday at an event in Washington, warning that excess U.S. AI regulation could damage American innovation in the industry. "China is not years and years behind us in AI. Maybe they're 3-6 months,' said Sacks, speaking at the AWS summit in Washington. "It's a very close race."
Yahoo
4 hours ago
- Yahoo
Big Bang theory is wrong, claim scientists
The Big Bang theory is wrong and the universe is sitting inside a black hole, scientists have suggested. Researchers have believed everything that exists exploded from a single point of infinite density, or singularity, since the 1930s, when Georges Lemaitre, a Belgian theoretical physicist, proposed that the universe emerged from a 'primeval atom' – the theory known as the Big Bang. Now an international team of physicists, led by the University of Portsmouth's Institute of Cosmology and Gravitation, has suggested instead that the universe formed following a huge gravitational collapse that generated a massive black hole. Matter within the black hole was crunched down before the huge amounts of stored energy caused it to bounce back like a compressed spring, creating our universe. The new theory has been named Black Hole Universe and suggests that, rather than the birth of the universe being from nothing, it is the continuation of a cosmic cycle. It also suggests that the edge of our universe is the event horizon of a black hole, from which light cannot escape, making it impossible for us to see beyond into our parent universe. It implies other black holes may also contain unseen universes. Prof Enrique Gaztañaga said: 'We've shown that gravitational collapse does not have to end in a singularity and found that a collapsing cloud of matter can reach a high-density state and then bounce, rebounding outward into a new expanding phase. 'What emerges on the other side of the bounce is a universe remarkably like our own. Even more surprisingly, the rebound naturally produces a phase of accelerated expansion driven not by a hypothetical field but by the physics of the bounce itself. 'We now have a fully worked-out solution that shows the bounce is not only possible – it's inevitable under the right conditions.' The Big Bang theory was based on classic physics, but scientists have struggled to make it fit with known effects of quantum mechanics, which sets a limit on how much matter can be compressed. Physicists such as Roger Penrose and Prof Stephen Hawking had suggested that gravitational collapse inside a black hole must lead to a singularity, but under the new model that does not need to happen. Matter does not need to crunch down infinitely, just enough so it can bounce back. Unlike the Big Bang theory, the new theory model aligns with both the general theory of relativity and quantum physics. Prof Gaztañaga added: 'In contrast to the famous singularity theorems by Penrose and Hawking, which assume that matter can be compressed indefinitely, we rely on the fact that quantum physics places fundamental limits on how much matter can be compressed. 'The Black Hole Universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger 'parent' universe. 'We are not special. We are not witnessing the birth of everything from nothing, but rather the continuation of a cosmic cycle – one shaped by gravity, quantum mechanics, and the deep interconnections between them.' The theory that the universe might exist inside a black hole was first proposed in 1972 by Raj Kumar Pathria, an Indian theoretical physicist, but gained little traction. However, recent observations by the James Webb Space Telescope have reignited interest in the concept. In March, images of early galaxies showed that two-thirds were spinning clockwise, while a third were rotating anti-clockwise. In a random universe, the distribution should be even – so something was causing an anomaly. One explanation is that the universe was born rotating, which would occur if it had been created in the interior of a black hole. Lior Shamir, an associate professor of computer science at Kansas State University said: 'That explanation agrees with theories such as black hole cosmology, which postulates that the entire universe is the interior of a black hole.' Black holes form when the core of a massive star collapses under its own galaxy, leading to a supernova explosion. They cannot be seen because of the strong gravity that is pulling light into the black hole's centre. However, scientists can see the effects of its strong gravity on the stars and gases around it, and it sometimes forms an accretion disc of spiralling gas which emits x-rays. Under the theory of black hole cosmology, each black hole could produce a new 'baby universe' connected to the outside universe through a an Einstein-Rosen bridge, or a 'wormhole'. Scientists are hoping that the new model may be able to explain other mysteries in the universe, such as the origin of supermassive black holes, the nature of dark matter, or the formation and evolution of galaxies. The new research was published in the journal Physical Review D. Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.
Yahoo
7 hours ago
- Yahoo
Universe was not formed in big bang but ‘bounced' out of black hole
The Universe may not have started with the Big Bang, but instead 'bounced' out of a massive black hole formed within a larger 'parent' universe, according to a new scientific paper. Professor Enrique Gaztanaga, from the University of Portsmouth's Institute of Cosmology and Gravitation, said that the current Big Bang theory was problematic as the laws of physics 'broke down' when used to explain it. His new explanation, published in the journal Physical Review D, suggests that the Universe was formed as a result of a gravitational collapse in a larger universe which generated a massive black hole leading to a rebound or 'bounce' causing our universe to emerge. Professor Gaztanaga said: 'The Big Bang model begins with a point of infinite density where the laws of physics break down. 'This is a deep theoretical problem that suggests the beginning of the Universe is not fully understood. 'We've questioned that model and tackled questions from a different angle – by looking inward instead of outward. 'Instead of starting with an expanding universe and asking how it began, we considered what happens when an over-density of matter collapses under gravity.' Prof Gaztanaga explained that the theory developed by his team of researchers worked within the principles of quantum mechanics and the model could be tested scientifically. He said: 'We've shown that gravitational collapse does not have to end in a singularity and found that a collapsing cloud of matter can reach a high-density state and then bounce, rebounding outward into a new expanding phase. 'Crucially, this bounce occurs entirely within the framework of general relativity, combined with the basic principles of quantum mechanics. What emerges on the other side of the bounce is a universe remarkably like our own. 'Even more surprisingly, the rebound naturally produces a phase of accelerated expansion driven not by a hypothetical field but by the physics of the bounce itself. 'We now have a fully worked-out solution that shows the bounce is not only possible – it's inevitable under the right conditions. 'One of the strengths of this model is that it makes predictions that can be thoroughly tested. And what's more this new model has also revealed that the Universe is slightly curved, like the surface of the Earth.' He added: 'Furthermore, it could also shed new light on other deep mysteries in our understanding of the early universe such as the origin of supermassive black holes, the nature of dark matter, or the formation and evolution of galaxies.' Prof Gaztanaga, who is the science co-ordinator for the ARRAKIHS ESA space mission, said that the four wide-angle telescopes on the satellite could help confirm the theory through its ability to detect ultra-low surface brightness structures in the outskirts of galaxies which he explained were essential for studying how galaxies grow and evolve.
