Latest news with #generalrelativity
Yahoo
16-05-2025
- Science
- Yahoo
New theory could finally make quantum gravity a reality
When you buy through links on our articles, Future and its syndication partners may earn a commission. Physicists have developed a novel approach to solving one of the most persistent problems in theoretical physics: uniting gravity with the quantum world. In a recent paper published in the journal Reports on Progress in Physics, the scientists outline a reformulation of gravity that could lead to a fully quantum-compatible description — without invoking the extra dimensions or exotic features required by more speculative models, like string theory. At the heart of the proposal is a rethinking of how gravity behaves at a fundamental level. While the electromagnetic, weak and strong forces are all described using quantum field theory — a mathematical framework that incorporates uncertainty and wave-particle duality — gravity remains the outlier. General relativity, Einstein's theory of gravity, is a purely classical theory that describes gravity as the warping of space-time geometry by mass and energy. But attempts to blend quantum theory with general relativity often run into fatal mathematical inconsistencies, such as infinite probabilities. The new approach reinterprets the gravitational field in a way that mirrors the structure of known quantum field theories. "The key finding is that our theory provides a new approach to quantum gravity in a way that resembles the formulation of the other fundamental interactions of the Standard Model," study co-author Mikko Partanen, a physicist at Aalto University in Finland, told Live Science in an email. Instead of curving space-time, gravity in their model is mediated by four interrelated fields, with each one similar to the field that governs electromagnetism. These fields respond to mass in much the same way that electric and magnetic fields respond to charge and current. They also interact with each other and with the fields of the Standard Model in a way that reproduces general relativity at the classical level while also allowing quantum effects to be consistently incorporated. Related: 'Einstein's equations need to be refined': Tweaks to general relativity could finally explain what lies at the heart of a black hole Because the new model mirrors the structure of well-established quantum theories, it sidesteps the mathematical problems that have historically hindered efforts to quantize general relativity. According to the authors, their framework produces a well-defined quantum theory that avoids common problems — such as unphysical infinities in observable quantities and negative probabilities for physical processes — that typically arise when general relativity is quantized using conventional, straightforward methods. A key advantage of the approach is its simplicity. Unlike many models of quantum gravity that require undetected particles and additional forces, this theory sticks to familiar terrain. "The main advantages or differences in comparison with many other quantum gravity theories are that our theory does not need extra dimensions that do not yet have direct experimental support," Jukka Tulkki, a professor at Aalto University and co-author of the paper, told Live Science in an email. "Furthermore, the theory does not need any free parameters beyond the known physical constants." This means the theory can be tested without waiting for the discovery of new particles or revising existing physical laws. "Any future quantum gravity experiments can be directly used to test any (forthcoming) predictions of the theory," Tulkki added. Despite the promising features, the model is still in its early stages. Although preliminary calculations indicate that the theory behaves well under the usual consistency checks, a complete proof of its consistency remains to be worked out. Moreover, the framework has yet to be applied to some of the deepest questions in gravitational physics, such as the true nature of black hole singularities or the physics of the Big Bang. "The theory is not yet capable of addressing those major challenges, but it has potential to do so in the future," Partanen said. Experimental verification may prove even more elusive. Gravity is the weakest of the known forces, and its quantum aspects are incredibly subtle. Direct tests of quantum gravity effects are beyond the reach of current instruments. RELATED STORIES —In a first, physicists spot elusive 'free-range' atoms — confirming a century-old theory about quantum mechanics —Physicists create hottest Schrödinger's cat ever in quantum technology breakthrough —Scientists claim to find 'first observational evidence supporting string theory,' which could finally reveal the nature of dark energy "Testing quantum gravity effects is challenging due to the weakness of gravitational interaction," Tulkki said. Still, because the theory includes no adjustable parameters, any future experiment that probes quantum gravitational behavior could potentially confirm — or rule out — the new proposal. "Given the current pace of theoretical and observational advancements, it could take a few decades to make the first experimental breakthroughs that give us direct evidence of quantum gravity effects," Partanen said. "Indirect evidence through advanced observations could be obtained earlier." For now, Partanen and Tulkki's work opens up a fresh direction for theorists searching for a quantum theory of gravity — one that stays grounded in the successful frameworks of particle physics while potentially unlocking some of the most profound mysteries of the universe.
Yahoo
14-02-2025
- Science
- Yahoo
Fastest exoplanet ever is dragged through space at 1.2 million mph by hypervelocity star
When you buy through links on our articles, Future and its syndication partners may earn a commission. Is it a bird? Is it a plane? No, it's super Neptune! But this Superman-mimicking planet is not blasting through space on its own. It is being dragged along by its parent star. NASA scientists have discovered what they suspect is the hypervelocity star racing through space with a Neptune-like planet in tow. The system appears to be moving at an incredible speed of 1.2 million miles per hour (1.9 million kilometers per hour). If the discovery is confirmed, this will be the fastest extrasolar planet, "exoplanet," system ever seen. "We think this is a so-called super-Neptune world orbiting a low-mass star at a distance that would lie between the orbits of Venus and Earth if it were in our solar system," said team leader Sean Terry, a researcher at NASA's Goddard Space Flight Center. "If so, it will be the first planet ever found orbiting a hypervelocity star." The star and the planet it drags along with it were first hinted at in data collected way back in 2011 thanks to a chance alignment and a phenomenon first predicted by Albert Einstein in 1915 in his magnum opus theory, general relativity. Gravitational lensing becomes useful to planet-hunters when planets pass background stars not associated with them. The way these planets warp space causes a tiny shift in the stars' position when seen from Earth. This effect, called "microlensing," can therefore be used to detect otherwise dark planets way beyond the limits of the solar system that are effectively invisible using traditional light-based astronomy. In this case, the team detected a microlensing signal that indicated two cosmic objects. They determined one of these lensing bodies has a mass around 2,300 times greater than its companion, but weren't able to determine the exact masses of the objects because they were simply too far away."Determining the mass ratio is easy," team member David Bennett, a senior research scientist at the University of Maryland, College Park and NASA Goddard, said. "It's much more difficult to calculate their actual masses."Bennett was part of the team behind the 2011 discovery that suspected that the lensing bodies were a star with a mass around one-fifth of the sun's mass and a planet 29 times as massive as Earth. Alternatively, the first object could be a closer "rogue planet" with no parent star and a mass around 4 times that of Jupiter. That would have made the second lensing body a moon associated with this planet. To end this confusion, Bennett joined this new team, and they began scouring data collected by the Keck Observatory in Hawaii and the star-tracking spacecraft Gaia. The team reasoned that if this pair of lensing bodies were indeed a rogue planet and its trailing moon, then without the aid of lensed background starlight, they would be invisible. However, if this is a star dragging along a super Neptune, then, though the planet would be too faint to see, the light from the star should make it identifiable. This search seems to have been successful. The researchers spotted a strong suspect star located around 24,000 light-years from Earth. That places the star right by the central bulge of the Milky Way, where stellar bodies are densely packed. The team then looked at the star's position in 2011 and compared it to its location in 2021. The change in location over 10 years revealed the system's high speed. Though the scientists have estimated this star is dragging its exoplanet along at 1.2 million mph, what they have examined thus far represents its motions in just two star system could also be moving towards or away from Earth. If it is, this could push its speed up to over 1.3 million mph (600 kilometers per second).This is significant because that speed exceeds the escape velocity of the Milky Way. That means this hypervelocity star and its planet could be destined to escape the Milky Way and go intergalactic, though this process would take millions of years. Related Stories: — Hubble telescope sees an angry star and an evaporating planet — James Webb Space Telescope suggests this exoplanet is our 'best bet' at finding an alien ocean — 12 out-of-this-world exoplanet discoveries in 2023 The team will now attempt to conclusively determine if the lensing body spotted in 2011 is indeed this suspect star. "If high-resolution observations show that the star just stays in the same position, then we can tell for sure that it is not part of the system that caused the signal," team member and University of Maryland researcher Aparna Bhattacharya said. "That would mean the rogue planet and exomoon model is favored." Moving beyond this system, this team and other scientists will now attempt to discover more planets associated with hypervelocity stars. This search will get a major boost when the Nancy Grace Roman Space Telescope launches in May 2027. Roman could also help get to the bottom of what launches some stars with such incredible speeds. "In this case, we used MOA for its broad field of view and then followed up with Keck and Gaia for their sharper resolution, but thanks to Roman's powerful view and planned survey strategy, we won't need to rely on additional telescopes," Terry said. "Roman will do it all." The team's research was published on Tuesday (Feb. 10) in The Astronomical Journal.
