Latest news with #ReportsonProgressinPhysics
Yahoo
26-05-2025
- Science
- Yahoo
New theory could finally make 'quantum gravity' a reality — and prove Einstein wrong
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. 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: — Black holes may obey the laws of physics after all, new theory suggests — How 'quantum foam' may have inflated the early universe — Scientists find 'spooky' quantum entanglement on incredibly tiny scales — within individual protons "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
20-05-2025
- Science
- Yahoo
Scientists May Have Found a Way to Simplify Gravity. It Could Change Physics as We Know It.
Here's what you'll learn in this story. A new paper uses a simplified model to prove that gravity can be unified between quantum and standard physics. The simpler model still meets the established requirements for a robust unified gravity theory. Even if this theory does not prove revolutionary, it shows that new ways of thinking are possible. Two scientists in Finland are claiming to have advanced the cause of a unified theory of gravity, including 'a complete, renormalizable theory of quantum gravity.' Physicists have long tried to mesh gravity with the standard model of physics by, in a sense, comparing like with like—how can we describe gravity using measurable things in a way that aligns with how the standard model describes electromagnetic, weak, and strong forces? The key—according to the duo's new research, which appears now in the peer reviewed journal Reports on Progress in Physics—lies in a particular type of theory called a gauge. A gauge is a way to measure something that is comparable to other things, like India's narrow gauge railways. In physics, gauge theory helps scientists take all the measurable things they know and align them in order to find commonalities or definitions. Using an old English expression, we can define a duck as something that walks like a duck and quacks like a duck. Once something is a proverbial duck, many other properties—like its color, size, or area of origin—can't change its duck-ness. The duck-ness gauge only requires waddling and quacking. In this paper, physicists Mikko Partanen and Jukka Tulkki turn the universe at large into a bunch of overlapping, finite relationships of symmetry that act as microcosms of the entire standard model. They describe a system with eight dimensions, then break it into pieces that each use four of those dimensions. Finally, they write, '[f]our symmetries of the components of the space-time dimension field are used to derive a gauge theory, called unified gravity.' Basically, their goal was to find the mathematically smallest model that could still hold up to all the rules required of a theory of unified gravity (one that unites the standard model and quantum physics). This work finds a middle ground between a simplified 'toy model' and the complexity of a full model of spacetime. One of the keys is that, within a gauge relationship, many terms can simply be canceled out, the same way you may have learned to do in algebra and calculus. Partanen and Tulkki claim that by substituting new (but equivalent) values for parts of their formulae, they've created a gauge model that no longer relies on a contentious variable. 'In contrast to previous gauge theories of gravity, all infinities that are encountered in the calculations of loop diagrams can be absorbed by the redefinition of the small number of parameters of the theory in the same way as in the gauge theories of the Standard Model,' they conclude. In other words, gravity may not need to be as complicated as we've made it—at least, mathematically speaking. A key term in this research is normalization, or renormalization. This is a form of matching reality (and observable qualities within it) to the pure mathematics of a model. Any theory of unified gravity must hold up to how we measure the effects of gravity in our portion of spacetime—or anywhere else in the universe, for that matter. The scientists chose a compact model over a noncompact one, meaning that their model doesn't have any missing pieces that they aren't sure how to categorize. There's no quacking fish or waddling giraffe gumming up the works of what a duck must be. 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?
