Study finds black holes made from light are impossible — challenging Einstein's theory of relativity

New research suggests that extreme objects known as "kugelblitze" — black holes formed solely from light — are impossible in our universe, challenging Einstein's theory of general relativity. The discovery places significant constraints on cosmological models and demonstrates how quantum mechanics and general relativity can be reconciled to address complex scientific questions.

Black holes — massive objects with such a strong gravitational pull that not even light can escape their grasp — are among the most intriguing and bizarre objects in the universe. Typically, they form from the collapse of massive stars at the ends of their life cycles, when the pressure from thermonuclear reactions in their cores can no longer counteract the force of gravity.

However, more exotic hypotheses exist regarding black hole formation. One such theory involves the creation of a "kugelblitz," German for "ball lightning." (The plural form is "kugelblitze.")

"A kugelblitz is a hypothetical black hole that, instead of forming from the collapse of 'ordinary matter' (whose main constituents are protons, neutrons, and electrons), is formed from concentrating humongous amounts of electromagnetic radiation, such as light," study co-author José Polo-Gómez, a physicist at the University of Waterloo and the Perimeter Institute for Theoretical Physics in Canada, told Live Science in an email.

"Even though light does not have mass, it does carry energy," Polo-Gómez said,  adding that, in Einstein's theory of general relativity, energy is responsible for creating curvatures in space-time that result in gravitational attractions. "Because of that, it is in principle possible for light to form black holes — if we concentrate enough of it in a small enough volume," he said.

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These principles hold true under classical general relativity, which does not account for quantum phenomena. To explore the potential impact of quantum effects on kugelblitz formation, Polo-Gómez and his colleagues examined the influence of the Schwinger effect.