Black holes have long seemed to be the final word in cosmic finality, swallowing matter and merging but never dividing. A new theoretical study in Physical Review D, led in part by Francesco Sannino of the University of Naples Federico II, suggests that a black hole spinning at the very limit of what physics allows might, in principle, split into two distinct bodies. The idea runs against the universe's steady drift toward disorder, and it survives only under narrow conditions, so it remains a question about what gravity permits rather than a discovery about what the sky contains.
Theoretical Study Says Fast-Spinning Black Holes Could Split in Two, Though Only Under Narrow Conditions
A black hole can wear pants and come out as two
Mark
So what's the basic claim here? Black holes can split?
Mimi
In theory, yes, but only in a very narrow case. A black hole spinning at the maximum possible rate could have its event horizon form a pants shape, with two legs, and a new black hole comes out of each.
Mark
Why is splitting normally forbidden?
Mimi
Entropy. A non-rotating black hole dividing would mean a drop in disorder, which is thermodynamically unfavorable. Spin is what opens the loophole.
Luke
Before we get carried away, this is a theoretical paper. Nobody has observed a split, and the reporting doesn't say anyone has.
Mark
And the spin has to be extreme?
Mimi
Right. Slower spins don't let the two offspring separate enough, so they merge back into one. Sannino says the window largely closes again except near the maximum rate.
Luke
Worth noting that "possibly" is doing work in that quote. Even near-maximal spin is described as a possibility, not a confirmed outcome.
Mark
Is there any estimate of how likely this is?
Luke
No. Sannino says they can't give a single probability yet, because it depends on how gravity behaves beyond Einstein's theory. That part is unknown.
Mimi
And the team is working on quantifying it.
Mark
Could we ever see one?
Mimi
Gamma-ray telescopes might detect a split. The work also points to small black holes as the likelier candidates, not giant ones.
Luke
"Might" is the right word. The source doesn't say what signal to look for or how strong it would be.
Le Pouls
- A new paper proposes that a maximally spinning black hole could split in two, challenging the assumption that black holes only merge.
- Thermodynamics normally forbids such a division, since it would require entropy to fall, pushing the idea against a basic law of nature.
- Researchers have found a loophole in the form of a pants-shaped event horizon, but the offspring must separate far enough to avoid immediately re-merging.
- The window narrows to near-maximal spins, and no probability has been assigned, leaving the outcome dependent on gravity beyond Einstein and on whether gamma-ray telescopes can detect a split.
Black holes have long seemed to be the final word in cosmic finality, swallowing matter and merging but never dividing. A new theoretical study in Physical Review D, led in part by Francesco Sannino of the University of Naples Federico II, suggests that a black hole spinning at the very limit of what physics allows might, in principle, split into two distinct bodies. The idea runs against the universe's steady drift toward disorder, and it survives only under narrow conditions, so it remains a question about what gravity permits rather than a discovery about what the sky contains.
A black hole spinning as fast as physics allows might, under the right conditions, divide into two. That is the claim of a new theoretical study in Physical Review D, whose authors describe the process with a vivid image: the black hole "wears pants," sending itself down two separate tubes of spacetime and emerging as two bodies.
The work includes Francesco Sannino of the University of Naples Federico II. The researchers set out to ask which physical laws normally stop a black hole from splitting, and whether any circumstances could allow it. Mergers are familiar territory; splitting is far more esoteric.
The main obstacle is entropy, the measure of disorder that tends to rise over time. A non-rotating black hole dividing would require entropy to fall, which makes it thermodynamically unfavorable. The team found their loophole among rapidly spinning black holes, where the event horizon can take a pants-like shape with two legs, each ending in a new black hole. But the offspring must separate far enough to avoid falling back together, and once that requirement is included, only near-maximal spins remain plausible.
So the result shows a split is possible in principle, not how likely it is. The team cannot yet assign a probability, since the answer depends on how gravity behaves beyond Einstein. The authors suggest gamma-ray telescopes might one day detect such an event, and they note that splitting seems more likely for small black holes than for giant ones. For now it remains a theoretical result, and the next step is putting a number on the odds.
A black hole that spins as fast as physics allows might, under the right conditions, divide into two. That is the claim of a new theoretical study in the journal Physical Review D, whose authors describe the process with an image borrowed from tailoring: the black hole can "wear pants," sending itself down two separate tubes of spacetime and emerging as two distinct bodies.
The work comes from a team that includes Francesco Sannino of the University of Naples Federico II in Italy. In a statement about the paper, Sannino said the researchers set out to investigate which physical laws ordinarily stop a black hole from splitting in two, and whether any circumstances might permit it. Black hole mergers are familiar territory. A split is far more esoteric.
The obstacle is entropy, the thermodynamic measure of disorder in a system. The universe tends toward more disorder, which is why things decay and why a house grows messier unless someone adds energy by tidying. A non-rotating black hole that divided would require entropy to fall, a decrease in disorder. That makes the scenario, in the researchers' language, thermodynamically unfavorable.
That difficulty led the team to look at black holes spinning at high speed. There they found what they call a loophole. In this case the event horizon, the black hole's outer boundary, can take a pants-like shape, with two "legs" extending across space and time. One new black hole emerges at the end of each leg.
The loophole comes with a further constraint. The original black hole must be spinning at the maximum possible rate. If it spins any slower, the offspring would not separate far enough to avoid falling back together and merging into one again. Sannino put it this way: the two resulting black holes must be able to separate rather than immediately collapse back together, and once that requirement is included, the window largely closes again, except possibly for black holes rotating close to their maximum rate.
So the study shows a split is possible in principle, but it does not say how likely one is. Sannino said the team cannot yet give a single probability for a black hole to split. The answer depends on how gravity behaves beyond Einstein's theory, he said, and the researchers are working to quantify that.
There may be a way to look for such an event. The authors suggest a split could potentially be detected with gamma-ray telescopes. Anyone picturing giant cosmic monsters spawning smaller ones should adjust the image, though: the work suggests splitting is more likely to occur with small black holes.
For now this remains a theoretical result, resting on conditions that are narrow and on a gravitational framework still being worked out. The next step is the team's effort to put a number on the odds, which would tell astronomers whether gamma-ray searches are worth the attempt.
Citations marquantes
We cannot yet give a single probability for a black hole to split; it depends on how gravity behaves beyond Einstein's theory, and we are working to quantify this.— Francesco Sannino, University of Naples Federico II
Envie de l'histoire complète ?
Lire l'original sur Futurism ↗
Science & Space