A novel theoretical framework for gravity, conceptualized by researchers at Aalto University, offers a description consistent with the Standard Model of particle physics, potentially advancing our comprehension of the universe’s genesis.
The Standard Model of particle physics delineates electromagnetic, weak, and strong interactions, representing three of nature’s four fundamental forces. Integrating the fourth force, gravity, into this model has proven exceptionally difficult due to theoretical discrepancies between general relativity and quantum field theory. Whereas quantum field theory employs discrete, finite-dimensional symmetries tied to the intrinsic properties of quantum fields, general relativity is predicated on continuous, infinite-dimensional symmetries governing spacetime. Mikko Partanen and Jukka Tulkki endeavor to formulate a gauge theory of gravity utilizing compact, finite-dimensional symmetries, mirroring the structure of the Standard Model’s fundamental interactions. Image attribution: DESY / Science Communication Lab.
“Should this approach yield a comprehensive quantum field theory of gravity, it would eventually provide resolutions to profound challenges such as understanding singularities within black holes and the initial moments of the Big Bang,” stated Dr. Mikko Partanen of Aalto University.
“A theoretical construct that harmoniously accounts for all fundamental forces of the cosmos is often termed a Theory of Everything.”
“Certain fundamental enigmas in physics persist. For instance, current theoretical frameworks do not yet elucidate the prevalent asymmetry between matter and antimatter observed in our universe.”
The breakthrough hinged on devising a method to represent gravity within a suitable gauge theory—a theoretical framework where particles interact via a field.
“The most widely recognized gauge field is the electromagnetic field,” explained Dr. Jukka Tulkki from Aalto University.
“When particles possessing electrical charge interact, their engagement transpires through the electromagnetic field, which serves as the relevant gauge field.”
“Consequently, for particles endowed with energy, their interactions stemming solely from their energetic state would occur mediated by the gravitational field.”
A persistent obstacle for physicists has been the quest for a gauge theory of gravity that harmonizes with the gauge theories governing the other three fundamental forces: the electromagnetic force, the weak nuclear force, and the strong nuclear force.
The Standard Model of particle physics functions as a gauge theory that encompasses these three forces and possesses specific symmetrical properties.
“The central tenet is to establish a gauge theory of gravity that exhibits symmetry characteristics akin to those in the Standard Model, rather than grounding the theory in the fundamentally distinct spacetime symmetries inherent in general relativity,” Dr. Partanen elaborated.
In the absence of such a unified theory, physicists are unable to reconcile the two most potent theoretical paradigms: quantum field theory and general relativity.
Quantum theory offers a description of phenomena at the infinitesimal scale—where minute particles engage in probabilistic interactions—while general relativity characterizes the macroscopic realm of everyday objects and their gravitational interplay.
These represent distinct perspectives on our cosmos, and while both theories have undergone rigorous validation with exceptional accuracy, they remain fundamentally at odds.
Moreover, due to the inherent weakness of gravitational interactions, heightened precision is imperative for investigating genuine quantum gravity effects that extend beyond the purview of general relativity, which is a classical formulation.
“A quantum theory of gravity is indispensable for comprehending the nature of phenomena occurring in scenarios involving a gravitational field and elevated energy levels,” Dr. Partanen asserted.
“These conditions are prevalent in the proximity of black holes and during the nascent stages of the universe, immediately following the Big Bang—domains where established physical theories cease to be applicable.”
“Perpetually intrigued by the grandest questions in physics, we uncovered a novel, symmetry-driven methodology for the theory of gravity and commenced its development.”
“The resultant research holds immense promise for ushering in an entirely new epoch of scientific comprehension, akin to how the understanding of gravity ultimately paved the way for technologies such as GPS.”
While the theory presents a compelling prospect, the researchers acknowledge that its complete validation is not yet finalized.
The theoretical framework employs a specialized mathematical technique known as renormalization, a process designed to manage the infinities that emerge during calculations.
To date, Dr. Partanen and Dr. Tulkki have demonstrated the efficacy of this method up to a particular threshold—addressing what are termed ‘first-order’ terms—but they are obliged to confirm that these infinities can be effectively eliminated across the entirety of the computational process.
“If renormalization proves ineffective for higher-order terms, the calculations will yield infinite results,” Dr. Tulkki cautioned.
“Therefore, it is critical to establish the continued validity of this renormalization process.”
“A definitive proof is still required, but we hold a high degree of confidence in our eventual success.”
“While challenges remain, with sustained dedication and effort, we anticipate their resolution,” Dr. Partanen concluded.
“While I cannot provide an exact timeline, I can confidently state that significant advancements in our understanding will emerge within the next few years.”
The research conducted by the team is documented in a publication featured in the esteemed journal Reports on Progress in Physics.
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Mikko Partanen & Jukka Tulkki. 2025. Gravity generated by four one-dimensional unitary gauge symmetries and the Standard Model. Rep. Prog. Phys 88, 057802; doi: 10.1088/1361-6633/adc82e
