New data have been released that set fresh limits on quantum gravity, considered the missing link between general relativity and quantum mechanics. This theory has been sought by physicists for decades as it could potentially provide a unifying framework to explain the behavior of both the infinitely large and the infinitely small.
The new data comes from the Orca neutrino detector, located on the seabed of the Mediterranean off the coast of Toulon. Along with the Arca detector near the Sicilian coast of Capo Passero, it forms part of the Km3Net (Kilometer Cube Neutrino Telescope) underwater telescope.
The research, published online on the arXiv platform and in the Journal of Cosmology and Astroparticle Physics (JCAP), was conducted by the Km3Net collaboration, which includes hundreds of researchers from around the world.
While no signals predicted by quantum gravity were detected, the team studied the potential effects of quantum gravity on the ability of neutrinos to change identities. Neutrinos oscillate between three different identities following precise rules, and this process occurs regularly. Km3Net searched its data for any signs of irregularities, known as "decoherence," but none were found.
"Detecting neutrino decoherence would be a huge discovery," notes Nadja Lessing from the Instituto de Física Corpuscular at the University of Valencia and one of the authors of the study. "There are several quantum gravity theories that predict this effect because they suggest that neutrinos are not isolated systems, but can interact with their environment." Lessing adds that "from an experimental standpoint, we know that a signal of this type would involve the suppression of neutrino oscillations." The data suggests that "if quantum gravity does alter neutrino oscillations, it does so at an intensity below current sensitivity limits." This study sets tighter constraints on the intensity of this effect compared to previous experiments and provides directions for future research in the field.
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