Researchers Propose Mechanism for Tiny Black Holes to Form from 'Spacetime Crystals'

A team of physicists from Goethe University Frankfurt and the Vienna University of Technology (TU Wien) has published the first pen-and-paper, exact analytical solutions to Einstein's equations describing a process called critical collapse, in which spacetime organizes into a repeating, crystal-like pattern before potentially collapsing into a tiny black hole. The research, published in the May 2026 edition of Physical Review Letters, addresses a puzzle that has persisted since 1993, when numerical simulations first revealed that black hole formation near a critical threshold follows precise mathematical rules, hinting at a deeper underlying theory. The team's key methodological innovation was to examine the problem in the limit of infinitely many spatial dimensions, a counterintuitive approach that simplifies the mathematics of gravity and allowed hidden relationships to emerge. According to the researchers, a spacetime crystal sits at an unstable tipping point: a tiny injection of energy can push it to either disperse into radiation or collapse into a black hole, analogous to supercooled water crystallizing into ice with the slightest perturbation. The resulting black holes would be microscopic — potentially as small as a medium-sized asteroid in mass — and would rapidly evaporate by emitting Hawking radiation. The team notes that their formulas were surprisingly compact given the complexity of prior numerical simulations, which required thousands of CPU hours. While the work does not confirm the existence of primordial black holes, it provides a rigorous theoretical framework for understanding how they might have formed in the dense conditions of the early universe.