An international team of researchers has developed a revised theory of gravity that could solve one of physics’ greatest mysteries: how the universe was born. The so-called Gravidade Quântica Quadrática seeks to bridge the gap between the general relativity of Einstein and quantum mechanics in the early moments of Big Bang.
Liderado by Niayesh Afshordi, Universidade Professor of Waterloo and Instituto Perimeter, the study suggests that gravity itself contains the necessary ingredients to explain the initial expansion of the cosmos, without relying on additional hypothetical concepts. The work questions the traditional view of how the universe began.
The problem with the Einstein theory
General relativity, developed by Albert Einstein in 1915, is extraordinarily accurate at describing the universe on large scales. Contudo theory faces critical collapse when applied to the early moments of Big Bang and the interiors of black holes.
Nessas extreme conditions of density, temperature and curvature, the Einstein equations predict a singularity a point where density and temperature become infinite. “This usually indicates that the theory is being pushed beyond what is reliable,” explains Afshordi. General relativity simply does not work at energies as high as those that existed at the birth of the cosmos.
Cientistas has been trying to resolve this incompleteness for decades. The standard approach has been to accept general relativity and then add extra layers of theory—mostly a hypothetical inflation field—to explain how the universe expanded so quickly just after Big Bang.
Como the new gravity works
The proposal by Afshordi and his team reverses this logic. Instead of repairing general relativity with additional ingredients, they extended the theory of gravity itself so that it remains consistent even at extremely high energies. Essa extension is what physicists call “ultraviolet completeness.”
“Our approach asks whether some of this behavior in the early universe could come directly from gravity, once it is stretched in a way that behaves better at extreme energies,” said Afshordi. Gravidade Quântica Quadrática maintains the Einstein equations as a base, but adds mathematical terms that ensure the theory works on any energy scale.
Surpreendentemente, when the team applied this extended gravity to Big Bang, an inflation-like phase naturally emerged from the equations. Não needed to be entered manually. “It was impressive that it could emerge from gravity itself,” said Afshordi. The model also potentially eliminates the concept of an initial singularity, that impossible point where everything would be infinite.
Testes observations on the horizon
The researchers point to two main directions for future research:
- Melhorar the theoretical understanding of the model and testing its robustness beyond the simplified scenarios already studied
- Elaborar clear observational predictions that distinguish this theory from more conventional inflation models
- Procurar specific patterns in primordial gravitational waves
- Analisar subtle marks in the cosmic microwave background (CMB), a cosmic fossil remnant of the universe’s first light
- Usar data from future observations to confirm or refute the hypothesis
“These are some of the few probes that can tell us directly about physics in extremely remote times,” explained Afshordi. If future observations detect the correct pattern of primordial gravitational waves, or distinctive marks on the CMB predicted by the model, it would provide a concrete way to test whether this view of the early universe is correct.
Ajuste with current data
The proposed model fits very well with currently available cosmological data. In some cases, it fits observations better than many standard inflation models. Isso does not prove that the theory is correct, more time and observations are needed but it offers hope that this path can lead to genuine answers.
Quantum gravity represents the Santo Graal of theoretical physics. Unificar general relativity with quantum mechanics would fill a fundamental gap in our understanding of nature. Isso would explain how the universe works on vast cosmic scales and also on tiny subatomic scales where the two theories are incompatible.
If Afshordi and his team’s approach turns out to be correct, it will not only explain Big Bang more consistently. Também would mean that Einstein was almost certain his theory needed only a natural extension to work at truly extreme energies, with no need for additional radically new concepts.