New research suggests that extreme objects known as “kugelblitze” – black holes formed solely from light – are impossible in our universe, posing a challenge Einstein’s general theory of relativityThe discovery imposes significant constraints on cosmological models and shows how quantum mechanics and general relativity can be used to solve complex scientific questions.
Black holes —massive objects with such strong gravity that not even light can escape their grasp—are among the most intriguing and bizarre objects in the universe. They are typically created by the collapse of massive stars at the end of their life cycles, when the pressure of thermonuclear reactions in their cores exceeds the power of gravity.
However, there are more exotic hypotheses about the formation of black holes. 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), forms from the concentration of enormous amounts of electromagnetic radiation, such as light,” said study co-author José Polo-Gómeza physicist at the University of Waterloo and the Perimeter Institute for Theoretical Physics in Canada, in an email to Live Science.
“Even though light has no mass, it does carry energy,” Polo-Gómez said, adding that in Einstein’s general theory of relativity, energy is responsible for creating warps in space-time that result in gravitational pulls. “That’s why it’s possible in principle for light to form black holes — if we concentrate enough of it into a small enough volume,” he said.
Related: Modification to Schrödinger’s cat equation could unify Einstein’s theory of relativity and quantum mechanics, research suggests
These principles hold under classical general relativity, which does not account for quantum phenomena. To investigate the potential impact of quantum effects on the formation of kugelblitz, Polo-Gómez and his colleagues investigated the influence of the Schwinger effect.
“When there is incredibly intense electromagnetic energy — for example, from huge concentrations of light — some of this energy transforms into matter in the form of electron-positron pairs,” said the study’s lead author. Alvaro Alvarez-Domínguez from the Institute of Particle and Cosmos Physics (IPARCOS) at the Universidad Complutense de Madrid, told Live Science in an email. “This is a quantum effect called the Schwinger effect. It is also known as vacuum polarization.”
In their studywhich has been accepted for publication in the journal Physical assessment letters but has not yet been published, the team calculated the rate at which electron-positron pairs produced in an electromagnetic field would deplete energy. If this rate exceeds the rate of replenishment of the electromagnetic field’s energy in a given region, a kugelblitz cannot occur.
The team found that pure light, even under the most extreme conditions, can never reach the required energy threshold to form a black hole.
“What we prove is that kugelblitze are impossible to form by concentrating light, either artificially in the laboratory or in naturally occurring astrophysical scenarios,” said study co-author Luis J.Garayalso from IPARCOS, Live Science told. “Even if we have, for example, the most intense lasers On Earth, we would still be more than 50 orders of magnitude away from the intensity needed to create a kugel blitz.”
This finding has profound theoretical implications, significantly limiting previously considered astrophysical and cosmological models that assume the existence of kugelblitze. It also ends any hope of experimentally studying black holes in laboratory settings by creating them via electromagnetic radiation.
However, the positive outcome of the research shows that quantum effects can be efficiently integrated into problems involving gravity, thereby providing clear answers to current scientific questions.
“From a theoretical point of view, this work shows how quantum effects can play an important role in understanding the formation mechanisms and appearance of astrophysical objects,” said Polo-Gómez.
Inspired by their findings, the researchers plan to further investigate the influence of quantum effects on various gravitational phenomena of both practical and fundamental importance.
“A number of us are very interested in continuing the study of the gravitational properties of quantum matter, particularly in scenarios where this quantum matter violates traditional energy constraints,” he said. Eduardo Martin-Martínezalso from the University of Waterloo and the Perimeter Institute. “This type of quantum matter could in principle give rise to exotic spacetimes, resulting in effects such as repulsive gravity or producing exotic solutions like the Alcubierre warp drive or traversable wormholes.”