Latest news with #gravity
The Independent
2 days ago
- General
- The Independent
Universe may have started inside black hole, not from Big Bang
The universe may not have begun with the Big Bang as is generally thought but from the collapse of a massive black hole, a new theory suggests. Current observations of our universe appear to support the Big Bang and cosmic inflation theories, which say that the early universe sprang into existence from a singular moment in space and time and rapidly blew up in size. The theories, however, leave many fundamental questions unanswered. For one, in the Big Bang model, the universe begins with a singularity, a point of infinite density where the laws of physics break down, making it difficult to understand what existed before the beginning. Two, after the explosion, the universe is said to have undergone accelerating expansion powered by yet unknown forces with strange properties. That is to say this model of cosmology explains the origin of the universe by introducing new forces and factors that have never been directly observed while still not explaining where everything came from. The new theory, described recently in the journal Physical Review D, probes what happens when the early universe's dense collection of matter collapses under gravity instead of tracing back how it all began. This is a process similar to what happens when stars collapse into black holes, but exactly what is inside these dense cosmic entities remains a mystery. Current theories state that, under typical conditions, the collapse of extremely dense matter inevitably leads to a singularity. But how exactly the rules of quantum mechanics, which dictate the behaviour of tiny particles, apply at the ultrasmall scales of a singularity is unknown. The new theory proposes that a gravitational collapse does not necessarily have to end in a singularity. It uses mathematical equations to show a collapsing cloud of matter can become extremely dense and then 'bounce' and rebound outward into a new expanding phase. 'The bounce is not only possible, it's inevitable under the right conditions,' study author Enrique Gaztanaga writes in The Conversation. 'The cosmological implication of this new approach is a novel understanding of the origin of the universe that emerges from the collapse and subsequent bounce of a spherically symmetric matter distribution.' The theory combines the framework of general relativity, which applies to largescale cosmic objects like stars and galaxies, with the principles of quantum mechanics that dictate how tiny atoms and particles behave. Crucially, it explains an early state universe without implying the existence of mysterious forces. The new theory is also testable as it predicts that the universe is not flat but slightly curved like the surface of the Earth, researchers say. If future observations can confirm that the shape of the universe indeed has a small curvature, it could suggest that it all began from a bounce. 'The smoking gun for our bouncing scenario is the presence of a small spatial curvature,' researchers write. Scientists hope further development of the theory can shed more light on current cosmic mysteries like the origin of monster black holes, the nature of dark matter, and factors influencing the evolution of galaxies. 'The black hole universe also offers a new perspective on our place in the cosmos,' Dr Gaztanaga writes. 'In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger 'parent' universe.'
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.
The Independent
14-05-2025
- Science
- The Independent
You think you know the moon? NASA scientists say think again
NASA scientists said Wednesday that they've unearthed new secrets about the moon. Specifically, they've gotten a better look at the celestial body's interior by analyzing gravity data collected from an orbiting spacecraft. What that analysis has found is a stark difference between the internal structures of the moon's near and far sides. The near side has vast plains formed by molten rock, but the far side is more rugged. The moon once began as a molten world, and much of its ancient surface is covered with lava. Some theories suggest volcanism two to three billion years ago resulted in differences to the planet's interior that would have caused radioactive elements to accumulate deep inside the near side's mantle. This study offers the strongest evidence for that theory yet. 'We found that the moon's near side is flexing more than the far side, meaning there's something fundamentally different about the internal structure of the moon's near side compared to its far side,' Ryan Park, supervisor of the Solar System Dynamics Group at NASA's Jet Propulsion Laboratory, explained in a statement. 'When we first analyzed the data, we were so surprised by the result we didn't believe it. So we ran the calculations many times to verify the findings. In all, this is a decade of work.' The findings were published in the journal Nature. To reach these conclusions, they developed a new gravity model of the moon, which helps look at variations in gravity as it orbits our blue marble. The variations cause the moon to flex due to Earth's tidal force. Just as the moon can dictate tides on Earth, the Earth exerts a gravitational pull on the moon. They used data on the motion of the GRAIL mission's Ebb and Flow spacecraft; it orbited the moon in 2011 and 2012. With the help of a supercomputer, the study's authors produced what they say is the most detailed gravitational map of the moon to date. A gravitational map, showing gravity measurements across the moon. Looking at their results and comparing them with other models, Park's team found a small but greater-than-expected difference in how much the hemispheres deform. In a separate study, they used the same technique to peer into the interior of Vesta, an object in the main asteroid belt between Mars and Jupiter. They found that Vesta likely has a small or no core, unlike previous theories. They recently applied a similar technique to Jupiter's volcanic moon Io, revealing that the fiery moon is unlikely to possess a global magma ocean. 'Gravity is a unique and fundamental property of a planetary body that can be used to explore its deep interior,' Park said. 'Our technique doesn't need data from the surface; we just need to track the motion of the spacecraft very precisely to get a global view of what's inside.'
Gizmodo
13-05-2025
- Science
- Gizmodo
computer simulations
Science Physics & Chemistry Gravity Could Be Proof We're Living in a Computer Simulation, New Theory Suggests Gravity may not be a fundamental force of nature, but a byproduct of the universe streamlining information like a cosmic computer.
Gizmodo
13-05-2025
- Science
- Gizmodo
theory of gravity
Science Physics & Chemistry Gravity Could Be Proof We're Living in a Computer Simulation, New Theory Suggests Gravity may not be a fundamental force of nature, but a byproduct of the universe streamlining information like a cosmic computer.
