A notable prediction of Einstein’s general theory of relativity, the theory that links space, time and gravity, is that rotating black holes have enormous amounts of energy available to exploit.
For the past 50 years, scientists have tried to devise methods to unleash this power. Nobel physicist Roger Penrose theorized that the disintegration of a particle could draw energy from a black hole; Stephen Hawking proposed that black holes can release energy through quantum mechanical emission; while Roger Blandford and Roman Znajek have suggested the electromagnetic couple as the main agent of energy extraction.
Now in a study published in the journal Physical revision D, physicists Luca Comisso of Columbia University and Felipe Asenjo of Universidad Adolfo Ibanez in Chile, have found a new way to extract energy from black holes by breaking and rejoining magnetic field lines near the event horizon, the point from which nothing not even light can escape the gravitational pull of the black hole.
“Black holes are commonly surrounded by a hot ‘soup’ of plasma particles carrying a magnetic field,” said Luca Comisso, a researcher at Columbia University and first author of the study.
“Our theory shows that when magnetic field lines disconnect and reconnect, in the right way, they can accelerate plasma particles to negative energies and large amounts of black hole energy can be extracted.”
This discovery could allow astronomers to better estimate the rotation of black holes, drive energy emissions from black holes, and could even provide an energy source for the needs of an advanced civilization, Comisso said.
Comisso and Asenjo built their theory on the premise that the reconnection of magnetic fields accelerates plasma particles in two different directions. One flow of plasma is pushed against the black hole’s rotation, while the other is pushed in the direction of rotation and can escape the black hole’s clutches, which releases energy if the plasma engulfed by the black hole has negative energy.
“It’s as if a person could lose weight by eating negative calorie candy,” said Comisso, who explained that essentially a black hole loses energy by eating particles of negative energy. “This might sound strange,” he said, “but it can happen in a region called the ergosphere, where the space-time continuum rotates so fast that every object rotates in the same direction as the black hole.”
Within the ergosphere, magnetic reconnection is so extreme that plasma particles are accelerated to speeds approaching the speed of light.
Asenjo, professor of physics at Universidad Adolfo Ibáñez and co-author of the study, explained that the high relative velocity between captured and runaway plasma streams is what allows the proposed process to extract huge amounts of energy from the black hole. .
“We have calculated that the plasma energization process can achieve an efficiency of 150 percent, much higher than any power plant operating on Earth,” Asenjo said. “Achieving an efficiency greater than 100 percent is possible because black holes lose energy, which is given away for free to the plasma that escapes from the black hole.”
The energy extraction process envisaged by Comisso and Asenjo may already be operational in a large number of black holes. This may be what is driving black holes: powerful bursts of radiation that can be detected by Earth.
“Our increased knowledge of how magnetic reconnection occurs near the black hole could be crucial to guide our interpretation of current and future black hole telescope observations, such as those of the Event Horizon Telescope,” said Asenjo.
While it may sound like science fiction, extracting energy from black holes could be the answer to our future energy needs.
“Thousands or millions of years from now, humanity may be able to survive around a black hole without harnessing the energy of the stars,” Comisso said. “It’s essentially a technological problem. If we look at physics, there’s nothing stopping it.”
The study, magnetic reconnection as a mechanism for extracting energy from rotating black holes, was funded by the National Science Foundation’s Windows on the Universe initiative, NASA, and the National Science and Technology Development Fund of Chile.
Vyacheslav (Slava) Lukin, program director at NSF, said the Foundation aims to catalyze new theoretical efforts based on frontier observations in facilities such as the EHT, bringing theoretical physics and observational astronomy together under one roof.
“We look forward to the potential translation of seemingly esoteric studies of black hole astrophysics into the practical realm,” said Lukin.
“The ideas and concepts discussed in this work are truly fascinating,” said Vyacheslav (Slava) Lukin, program director at the National Science Foundation. He said NSF aims to catalyze new theoretical efforts based on frontier observations, bringing theoretical physics and observational astronomy together under one roof.
“We look forward to the potential translation of seemingly esoteric studies of black hole astrophysics into the practical realm,” he added.
Black holes acquire new powers when they rotate fast enough
Luca Comisso and Felipe A. Asenjo. Magnetic reconnection as a mechanism for extracting energy from rotating black holes. Phys. Rev. D. DOI: 10.1103 / PhysRevD.103.023014, journals.aps.org/prd/accepted/… 304179756dd56a93a764
Provided by Columbia University
Quote: Could we harness energy from black holes? (2021, January 13) retrieved January 14, 2021 from https://phys.org/news/2021-01-harness-energy-black-holes.html
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