A remarkable prediction of Einstein’s theory of general 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 come up with methods to unleash this power. Nobel physicist Roger Penrose theorized that a disintegration of particles could extract energy from a black hole; Stephen Hawking proposed that black holes could release energy through quantum mechanical emissions; while Roger Blandford and Roman Znajek suggested electromagnetic torque as the main energy extraction agent.
Now in a study published in the journal Physical review 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 reintroducing magnetic field lines near the event horizon, from which nothing, not even light, can not escape the gravitational pull of the black hole.
“Black holes are usually surrounded by a hot ‘soup’ of plasma particles carrying a magnetic field,” said Luca Comisso, a researcher at Columbia University and the study’s lead author.
“Our theory shows that when magnetic field lines are disconnected and reconnected correctly, they can accelerate plasma particles to negative energies and large amounts of black hole energy can be extracted.”
This finding could allow astronomers to better estimate the rotation of black holes, drive black hole energy emissions, and even provide an energy source for the needs of an advanced civilization, Comisso said.
Comisso and Asenjo built their theory on the premise that reconnecting magnetic fields accelerates plasma particles in two different directions. One plasma stream is pushed against the rotation of the black hole, while the other is propelled in the direction of rotation and can escape the claws of the black hole, which releases energy if the plasma swallowed by the black hole has negative energy.
“It’s like a person could lose weight by consuming negative calorie candies,” said Comisso, who explained that, in essence, a black hole loses energy by consuming negative energy particles. “This may seem strange,” he said, “but it can happen in a region called the ergosphere, where the space-time continuum rotates so fast that each object rotates in the same direction as the black hole.”
Inside the ergosphere, the magnetic reconnection is so extreme that the plasma particles are accelerated to speeds close to the speed of light.
Asenjo, a professor of physics at Adolfo Ibáñez University and co-author of the study, explained that the relatively high speed between captured and leaking plasma flows is what allows the proposed process to extract massive amounts of energy from the black hole.
“We have calculated that the plasma energization process can reach an efficiency of 150%, much higher than any power plant operating on Earth,” Asenjo said. “Achieving greater than 100% efficiency is possible because black holes drain energy, which is provided free of charge to the plasma coming out of the black hole.”
The energy extraction process envisaged by Comisso and Asenjo could already operate in a large number of black holes. This may be what causes rocket black holes – strong explosions of radiation that can be detected from Earth.
“Our increased knowledge of how magnetic reconnection occurs in the vicinity of the black hole could be crucial in guiding our interpretation of current and future observations of the black hole telescope, such as those at the Event Horizon Telescope,” said Asenjo.
Although 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 could be able to survive around a black hole without harnessing the energy of the stars,” said Comisso. “It’s essentially a technological issue. 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 Windows on the Universe initiative of the National Science Foundation, NASA and the National Fund for Scientific and Technological Development in Chile.
Vyacheslav (Slava) Lukin, program director at NSF, said that the Foundation aims to catalyze new theoretical efforts based on frontier observations at facilities such as EHT, bringing together theoretical physics and observational astronomy under one roof.
“We look forward to the potential translation of seemingly esoteric studies of black hole astrophysics into practice,” Lukin said.
“The ideas and concepts discussed in this paper 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 together theoretical physics and observational astronomy under one roof.
“We look forward to the potential translation of the seemingly esoteric studies of black hole astrophysics in practice,” he added.
Black holes gain new strength when they rotate fast enough
Luca Comisso and Felipe A. Asenjo. Magnetic reconnection as a mechanism for extracting energy from rotating black holes. Physical. Rev. D. DOI: 10.1103 / PhysRevD.103.023014, journals.aps.org/prd/accepted/ … 304179756dd56a93a764
Provided by Columbia University
Citation: Could we use the energy from the 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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