With the recent calculations, “you really are learning about quantum gravity,” Goon said. The newfound formula applies to a system such as a gas as well as a black hole. In a paper published in March in Physical Review Letters, Goon and Riccardo Penco broadened the lessons of the earlier work by proving a simple, universal formula relating energy and entropy. In the latest surprise, that link turns out to exemplify a general fact about nature. “It’s like, wow, OK, two very cool things are connected,” Cheung said. Entropy is one of the most studied features of black holes, but it wasn’t thought to have anything to do with their extremal limit. Then, two years ago, Remmen and collaborators Clifford Cheung and Junyu Liu of the California Institute of Technology discovered that whether extremal black holes can decay depends directly on another key property of black holes: their entropy - a measure of how many different ways an object’s constituent parts can be rearranged. This conclusion brought greater scrutiny to extremal black holes’ fates. Investigating the possibilities has led researchers in recent years to major clues about quantum gravity.įour physicists realized in 2006 that if extremal black holes can decay, this implies that gravity must be the weakest force in any possible universe, a powerful statement about quantum gravity’s relationship to the other quantum forces. Physicists strongly suspect that extremal black holes must decay, resolving the paradox, but by some other route than Hawking evaporation. So “there is a question,” said Sera Cremonini of Lehigh University: “What happens to all these extremal black holes?” There’s no fundamental principle protecting these black holes, so physicists don’t think they should last forever. In that case, the universe of the far future will be littered with tiny, indestructible black hole remnants - the remains of any black holes that carry even a touch of charge, since they’ll all become extremal after evaporating enough. It can’t evaporate further.īut the idea that an extremal black hole “stops radiating and just sits there” is implausible, said Grant Remmen, a physicist at the University of California, Berkeley. It’s then as small as it can get, given how charged it is. When a charged black hole evaporates and shrinks in the manner described by Hawking, it will eventually reach this extremal limit. Physicists calculate that black holes have an “extremal limit,” a saturation point where they store as much electric charge as possible for their size. More recently, physicists have considered the extreme of the extreme - entities called extremal black holes - and found a fruitful new problem.īlack holes become electrically charged when charged stuff falls into them. Black hole evaporation has informed quantum gravity research ever since. In 1974, the British physicist calculated that quantum jitter at the surfaces of black holes cause them to evaporate, slowly shrinking as they radiate heat. Plumbing black holes for knowledge of quantum gravity originated with Stephen Hawking. Thus generations of physicists have looked to black holes for clues about the true, quantum origin of gravity, which must fully reveal itself in their hearts and match Einstein’s approximate picture everywhere else. Albert Einstein equated the force of gravity with curves in the space-time continuum, but the curvature grows so extreme near a black hole’s center that Einstein’s equations break. These invisible spheres form when matter becomes so concentrated that everything within a certain distance, even light, gets trapped by its gravity. “The fact that you can’t go further, that something is changing, something is blocking you - something interesting is happening there.”įor decades, black holes have played the headlining role in the thought experiments that physicists use to probe nature’s extremes. “Physicists like to probe the extreme,” said Garrett Goon, a physicist at Carnegie Mellon University.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |