This strange “spacetime crystal” can suddenly become a black hole

A drop of water freezing at zero degrees. It sounds mundane, but that simple phase transition is helping physicists understand one of the universe's most dramatic phenomena: the spontaneous birth of a black hole.

Researchers at Goethe University Frankfurt and TU Wien have derived the first exact mathematical formula describing how microscopic black holes could form from a kind of "spacetime crystal," an unstable, repeating structure that teeters between dissolving and collapsing. "If a tiny amount of energy is added," says Professor Daniel Grumiller of TU Wien, "the inconspicuous spacetime crystal turns into a black hole."

The trick that unlocked this formula? Doing the math in infinite dimensions, then working backward toward our familiar four-dimensional universe.

Computer simulations have hinted at this possibility since 1993. Now, for the first time, researchers have matched those simulations with pencil-and-paper equations, opening a new analytical window into black hole formation and the extreme physics of the early universe.