In February 2023, the KM3NeT neutrino telescope near Sicily detected a particle with energy 35 times higher than previously observed levels. Researchers led by Dieter Lüst from the Max Planck Institute for Physics suggest the particle originated from a primordial black hole explosion within a fifth dimension, as detailed in Physical Review D.
The hypothesis incorporates the 'dark dimension' theory proposed by Cumrun Vafa, where a fifth dimension exists as a micron-sized circle. In this model, only neutrinos can escape into our four-dimensional space during a black hole collapse, explaining the absence of accompanying photons. The black hole itself is theorized to have formed from collapsing cosmic strings.
The IceCube detector at the South Pole, which has been operational since 2011 and covers a volume 20 times larger than KM3NeT, has not recorded similar events. Researchers suggest the particle may have been emitted in a narrow cone that missed IceCube but hit KM3NeT. Critics note that the existence of a fifth dimension remains unproven.
Future verification of such hypotheses relies on new infrastructure. The Radio Neutrino Observatory currently under construction in Greenland and the proposed second generation of IceCube aim to cover larger areas using radio signals to detect high-energy particles. Conventional explanations, such as blazars or cosmic rays, remain under consideration.
