Squeeze enough stuff into one place, space-time itself collapses into a sweet cosmic kiss known as a black hole.
In terms of Einstein’s sums, these “things” include the massless glow of electromagnetic radiation. Since E = mc2which describes the equivalence between matter and energy, the energy of light alone should – in theory – be able to create a black hole if enough of it is concentrated in one place.
Before you break out the big-gun lasers and punch holes in the floorboards of space, there’s one thing scientists at the Complutense University of Madrid in Spain and the University of Waterloo in Canada want you to know.
Something called the Schwinger effect can make the whole thing impossible before you even start.
Einstein’s general theory of relativity is a description of the distortion of space and time in relation to the presence of energy, such as that contained in matter. Put enough matter in one place and the distortion becomes so extreme that nothing – not even light – escapes.
In the mid-1950s, the American theoretical physicist John Wheeler discovered that there was nothing in Einstein’s theory to rule out the possibility that energy in a sufficient concentration of gravitational or electromagnetic waves could warp space-time enough to keep those same waves trapped in place. .
He called this exotic object a geon and considered it to be a kind of hypothetical, highly unstable particle.
Today, geons are a holdover from the age of scientific reasoning that also gave us wormholes and white holes; theoretical toys that tell us more about the limits of mathematical models than about physical reality.
Still, a form of geon that Wheeler referred to as “kugelblitz” appears now and then in science fiction as a fantastic source of energy. German for “ball lightning,” these tiny proton-sized black holes were designed to form in an intense focus of incredibly energetic beams of light, like a futuristic high-powered laser.
While general relativity gives kugelblitz the green light, quantum physics has its doubts. So theoretical physicist Álvaro Álvarez-Domínguez from the Complutense University in Madrid and his team ran numbers on the behavior of electromagnetic fields when their energy rises to extreme levels.
The quantum landscape is like a casino, where waves of possibilities keep rolling in like non-stop roulette wheels. Small bets rarely pay off, but accumulate enough money for one table and you’re almost guaranteed to win.
A similarly strong electromagnetic field in otherwise empty space almost guarantees that pairs of electrons and positrons will emerge from the quantum flood of infinite possibilities.
In a paper that has yet to be peer-reviewed, Álvarez-Domínguez and his team showed that this phenomenon, known as the Schwinger effect, would prevent the formation of a kugelblitz ranging in size from nearly twice the size of Jupiter to a fraction of the size of a proton.
In fact, the accumulation of all light in one place would provide the necessary energy for pairs of charged particles to form and fly away at close to the speed of light, preventing the growing dent in spacetime from ever forming a black hole—defining the event horizon.
“Our analysis strongly suggests that the formation of black holes from electromagnetic radiation alone is impossible, either by concentrating light in a hypothetical laboratory environment or in naturally occurring astrophysical phenomena,” the team writes in their analysis.
That doesn’t mean to completely rule out the possibility. Scientists admit that things could have been different in the “exceptionally extreme conditions” of the early universe.
Other forms of geon, such as those based on gravitational waves, remain a curiosity that may have also existed in the nascent universe billions of years in the past.
However, those now relying on kugelblitz-powered spacecraft to launch them to the stars may have to go back to the drawing board.
This paper is available on the arXiv preprint server.