Latest news with #GeneralRelativity
Yahoo
3 days ago
- Science
- Yahoo
Some Black Holes May Be Portals Through Spacetime In Disguise
Here's what you'll learn when you read this story: Theoretical physicists have long debated the possible existence of wormholes, which are mathematically possible, but no evidence points to their physical existence. One theory suggests that these hypothetical tunnels in spacetime could be masquerading as black holes, as both objects share similar characteristics as a result of existing right on the edge of where known physics breaks down. A new study adds more evidence to this conjecture by analyzing quasi-normal modes—distinctive vibrations in space-time caused by temporary perturbations—and finds that wormholes could mimic black holes in this particular context. Although traversable wormholes are a popular trope in sci-fi, the space-time structures that connect two different points of the universe are—at least, as of now—completely hypothetical. One of the first types of wormholes ever theorized, the Einstein-Rosen bridge, is simply a specific solution to Einstein's field equations, which map space-time geometry within certain matter and energy conditions. Sadly, these sci-fi dreams rest on the fantastical concept of 'negative energy,' a cosmic phenomenon that simply doesn't exist in the classical universe (though the answer isn't so clear cut in the quantum realm). Due to the space-time strangeness required to form a stable wormhole, some scientists have considered whether certain black holes might actually be wormholes in disguise. Although physical reality makes this a near-impossibility, mathematics shows that it's at least conceivable. Now, a new study has analyzed a certain attribute of Schwarzschild black holes—which are named for German physicist Karl Schwarzschild and are themselves hypothetical objects, as they're black holes that contain no rotation or electric field—known as quasi-normal modes (QNMs). These modes are considered quasi-normal because they describe distinctive vibrations of space-time when a compact object is perturbed (i.e. they don't continue indefinitely). Using different approaches—including a parameterization to define the properties of the area near the 'throat' of a wormhole while analyzing three different perturbation types (scalar, axial gravitational, and electromagnetic)—the researchers concluded that a wormhole could consistently replicate the QNMs associated with static (a.k.a. Schwarzschild) black holes. The results of the study were uploaded to the preprint server arXiv, and the authors note that the study will soon be published in the journal Physical Review D. 'Exotic compact objects—either beyond General Relativity (GR) predictions or arising from unconventional GR assumptions—could theoretically exist, though they remain undetected,' the authors wrote. 'This elusiveness may be due to their ability to closely mimic the observational properties of black holes.' The idea of wormholes masquerading as black holes of all shapes and sizes isn't a new one—in fact, it's a theory that's been debated for decades. More recently, a 2021 study pondered whether active galactic nuclei, or AGN, are actually wormhole mouths rather than supermassive black holes. A year later, a team from Sofia University in Bulgaria concluded that light emitted from a disk surrounding a traversable wormhole would likely be 'nearly identical' to that of a static black hole. Long-standing theories have also wondered if black holes could be paired with mirror twins, known as 'white holes,' which would together form wormholes. Of course, white holes have never been observed or detected either, but once again, the math allows for their existence. This new study adds to that growing discussion by analyzing the QNM aspect of static black holes and finding that the two are also similar. 'We can say that a wormhole can effectively emulate the Schwarzschild black hole in general relativity in its fundamental mode and first overtone across the three distinct perturbation types considered individually,' the authors wrote. The authors also expect to build on this approach by improving near-throat parameters and analyzing the polar gravitational perturbations theoretically exhibited by both wormholes and black holes (though the problem presents a few computational difficulties that will need solving). For now, wormholes remain firmly in the realm of science fiction. But with mathematics continuing to prove that such objects are possible, scientists will continue to search for these bridges across the universe. You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
TimesLIVE
16-05-2025
- Science
- TimesLIVE
UKZN's youngest PhD graduate 'unlocks secrets of gravity'
At 26 years old, Dr Shavani Naicker was the youngest doctoral graduate at the University of KwaZulu-Natal (UKZN) during its 2025 autumn graduation ceremonies — an achievement earned with a PhD in applied mathematics, specialising in astrophysics. Naicker's academic journey has been entirely home-grown, completing her BSc, BSc Honours and MSc degrees at UKZN — all summa cum laude. UKZN said her doctoral research, conducted under the guidance of Prof Sunil Maharaj and Dr Byron Brassel through the Astrophysics Research Centre (ARC), delved into the intricate theories of Einstein-Gauss-Bonnet gravity, part of Lovelock gravity, a higher-dimensional extension of Einstein's General Relativity. 'Lovelock gravity introduces higher-order curvature terms into the equations of gravity,' said Naicker. 'Studying these helps us understand gravitational interactions in extreme conditions, such as near black holes or in the early universe. My work contributes to uncovering the gravitational dynamics of astrophysical objects in higher dimensions, which could address some of the unresolved questions in cosmology and quantum gravity.' UKZN said her work produced new exact solutions to complex field equations — earning praise for its potential to shed light on how stars and black holes behave in extreme conditions. Maharaj, director of the ARC, called her research 'critical in understanding gravitational phenomena' and said it offers 'deep insights into the behaviour of stellar models'. Brassel, who taught and supervised Naicker over the years, described her as 'an astute student' and said he hopes their collaboration continues. Naicker is now a postdoctoral fellow at the ARC, supported by the National Research Foundation, and aims to one day become its director. Her work aligns with major scientific projects such as the MeerKAT and Square Kilometre Array telescopes. 'Obtaining a PhD in applied mathematics with a specialisation in relativistic astrophysics is the realisation of a lifelong dream,' said Naicker. 'It stands as testament to years of hard work, resilience and an enduring curiosity about the universe. I hope my journey inspires others — especially young women — to explore the fascinating world of science, technology, engineering and mathematics.'
Yahoo
19-04-2025
- Science
- Yahoo
Universe may revolve once every 500 billion years — and that could solve a problem that threatened to break cosmology
When you buy through links on our articles, Future and its syndication partners may earn a commission. In 1929, astronomer Edwin Hubble published a paper demonstrating that the universe is expanding. It gave rise to the Hubble constant, the number that describes how fast the universe is expanding. But it eventually created a puzzle, called the Hubble tension, because this cosmic expansion differs depending on what cosmic objects are used to measure it. A new mathematical model could resolve the Hubble tension by assuming the universe rotates. Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed? The new research, published in March in the journal Monthly Notices of the Royal Astronomical Society, suggests that our universe completes one revolution every 500 billion years. This ultraslow rotation could resolve the discrepancy between different measurements of the Hubble constant. "The standard concordance cosmological model has some wrinkles," study co-author István Szapudi, an astronomer at the Institute for Astronomy at the University of Hawai'i at Mānoa, told Live Science in an email. "A slow rotation of the universe could solve the Hubble puzzle." Astronomers measure the universe's rate of expansion in a few ways. One involves looking at supernovas — the explosive deaths of giant stars — and measuring how quickly these supernovas recede. The other method utilizes the cosmic microwave background, the radiation present 380,000 years following the Big Bang. However, these two measurements differ by about 10%. The idea of a rotating universe isn't new; mathematician Kurt Gödel introduced the idea in a 1949 paper published in the journal Reviews of Modern Physics. Other researchers, like Stephen Hawking, have also explored this theory. In the new study, the team applied the rotation to the Hubble tension. Because all celestial objects — including planets, stars, galaxies and black holes — rotate, this behavior naturally extends to the universe as a whole, the study authors proposed. "Much to our surprise, we found that our model with rotation resolves the paradox without contradicting current astronomical measurements," Szapudi said. RELATED STORIES —Scientists may have finally found where the 'missing half' of the universe's matter is hiding —Rare quadruple supernova on our 'cosmic doorstep' will shine brighter than the moon when it blows up in 23 billion years —Scientists discover smallest galaxy ever seen: 'It's like having a perfectly functional human being that's the size of a grain of rice' The proposed glacial speed at which the universe may rotate is too slow to detect, but it would still affect the universe's expansion rate and does not require new physics. However, the model only incorporated some of the physics thought to be at play. "We use Newtonian physics with some input from General Relativity," Szapudi said. "A complete [General Relativity] treatment would be desirable." He also explained that their work assumes the universe is uniform and did not vary in density as it evolved. In future investigations, the team will contrast the rotating-universe model against other cosmological models.
