Cosmic rays are elementary particles carrying colossal energy that pierce the intergalactic void. When two such particles smash head-on, the energy density at the point of impact could be enough to collapse into a black hole the size of an atomic nucleus. It poses no danger: just as a drop of water vanishes instantly on a scorching skillet, a microscopic black hole evaporates in a flash. This process, predicted by Stephen Hawking, is known as Hawking radiation, and its outcome is a stream of neutrinos — ghostly particles that barely interact with matter and thus pass freely even through a slab of lead.

Astronomers have already analyzed neutrino signals arriving from the galaxy TXS 0506+056. Their data show: if black holes do arise in such collisions, it happens only at energies where spacetime itself exhibits quantum effects, deviating from familiar geometry. The next generation of telescopes will allow deeper exploration of this realm. The key clue lies in the fact that during Hawking evaporation, a microscopic black hole must produce equal numbers of all three neutrino types (electron, muon, and tau neutrinos)—a distribution that stands out as an anomaly against the cosmic noise. Moreover, if extra spatial dimensions exist in nature, some neutrinos could momentarily slip into them and return, creating mysterious flashes in seemingly empty regions of space. Such a phenomenon would be the first hint of hidden realities where gravitational waves might propagate.