The Big Bang is often described as the moment when everything began – the point of infinite density where the laws of physics were broken. But what if that picture isn’t perfect?
A new study presents a different account of the birth of the universe: Instead of a sudden start from singularity, as predicted by Einstein’s theory of general relativitythe early universe may have passed through a more controlled high-energy phase governed by a modified theory of gravity known as QQG.
Why Einstein’s theory may not be enough
Einstein’s theory of general relativity was which is surprisingly successful in explaining gravity on a large scale. It explains the motion of the planets, the behavior of black holes, and the expansion of the universe. However, it struggles to explain the very small world of quantum mechanics and it is widely believed to have some fundamental inconsistencies.
“The big problem is that Einstein’s general relativity predicts its failure under extreme conditions, especially Big Bang unity,” said Afshordi.
At that point, the density and the bending moment become infinite – a clear indication that the theory is not true. Physicists have long been searching for a more comprehensive framework that would explain gravity under such conditions.
“What do [quadratic quantum gravity] what is interesting is that it can provide a mathematically stable way to describe gravity at very short distances and at very high energies, where normal relativity is expected to break down, “Afshordi said.”
A universe without unity
In a new study, the researchers examined how QQG could change the ancient time of the universe if it is the correct conclusion of Einstein’s theory. Their results suggest that the universe may not have started from a single point at all.
“Our main result is that, in a quadratic gravity, the very early universe could avoid the typical Big Bang singularity and instead go through a better controlled high-energy phase,” said Afshordi.
Instead of coming from an immeasurably dense state, the universe would begin with a simpler, more stable arrangement with greater density and relative temperature, with its precise characteristics depending on the particles and fields present at the highest energy and temperature. This avoids one of the more disturbing assumptions of the situation the study of cosmology.
The theory also provides a new perspective on cosmic inflation, a brief period of extremely rapid expansion that is thought to have occurred immediately after the Big Bang.
“In our analysis, this design can also reproduce inflation-like time without generating an additional artificial field by hand,” said Afshordi.
In conventional models, inflation is usually driven by a strange phenomenon known as the inflaton. That field has never been directly observed. On the other hand, QQG produces inflation naturally due to gravity itself.
“In other words, some of the key ingredients that we tend to add to cosmology can come directly from the theory of gravity itself,” Afshordi added.
From extraterrestrial physics to the ordinary universe
Another strange thing about QQG is that it works very differently depending on the size of the force. At very high energy, it obeys new quantum laws. But as the universe expands and cools, it returns to the normal physics described by Einstein.
The theory suggests that gravity becomes flexible at very high energies – a property known as asymptotic freedom – before it evolves into the form we see today. Eventually, the universe enters the hot, radiative phase described by standard cosmology.
This framework provides a continuous bridge between the primitive universe and the well-tested physics of modern times. An important question, however, is whether this idea can be tested.
“Yes, at least in principle,” said Afshordi. “The most promising experiments come from cosmology, especially from the picture of the early universe. magnetic waves and the cosmic microwave background.”
These ancient signs contain information about the early times of the universe. According to the new theory, these indicators should have subtle differences compared to estimates from standard inflation models.
“One very interesting aspect of our situation is that it can lead to unique predictions for the gravitational signal produced in the early universe,” said Afshordi. “As observational understanding improves over the coming years and decades, future measurements of gravitational waves may begin to distinguish this type of pattern from normal inflation.”
Although the theory is still being tested, it offers a strong possibility: that the Big Bang may not be a single beginning but part of a deeper, quantum explanation of gravity. If confirmed, this plan could change the way scientists understand the origin of the universe – replacing the breakdown of physics with a new, complete picture of the beginning of the universe.
Liu, R., Quintin, J., & Afshordi, N. (2026). Ultraviolet completion of the Big Bang in quadratic gravity. Physical Examination Letters, 136(11). https://doi.org/10.1103/6gtx-j455
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