Here’s how humans can use the power of black holes as batteries

Black holes have such intense gravitational pull that nothing can break free. Is there any way we could tap into the colossal power of black holes for energy? In a fresh study, scientists suggest two ways we could potentially use black holes for energy in the future. They came up with methods to harness energy from black holes based on their spin and gravitational characteristics.

“We know that we can extract energies from black holes, and we also know that we can inject energy into them, which almost sounds like a battery,” lead author Zhan Feng Mai, a postdoctoral researcher at the Kavli Institute for Astronomy and Astrophysics at Peking University, told Live Science.

In one imagined scenario, scientists would “charge” the black hole by shooting in huge, electrically charged particles. According to the study, published on Nov. 29 in the journal Physical Review D, these charges would keep getting drawn in until the black hole developed an electric field, pushing away any more charges they tried to shoot in.

Also Read: Here’s what next-gen Event Horizon Telescope will be able to do

Will the recharging process be efficient?

Once the electromagnetic push-back surpassed the black hole’s gravitational pull, scientists would label it as “fully charged.” Following Einstein’s general relativity theory, which equates mass to energy, the black hole’s energy would stem from both the injected electrical charges and the mass of those charges.

“The black hole battery is transforming the energy of the particle’s mass into charge energy,” Mai said.

The scientists crunched the numbers and figured out that the recharging process would be about 25% efficient. This means that black hole batteries could convert roughly a quarter of the inputted mass into usable energy in the shape of an electric field. According to the team’s calculations, this would make the battery’s efficiency around 250 times greater than that of an atomic bomb.

To get the energy out, the researchers would use a method called superradiance. This relies on the idea that the gravitational field of a spinning black hole literally drags space-time around its rotation.

Gravitational or electromagnetic waves entering this rotating area would be pulled along, but if they hadn’t crossed the black hole’s point of no return (event horizon) yet—where even light can’t escape—some waves might bounce back with more energy than they started with, according to the researchers. This would transform the black hole’s rotational energy, tied to its mass, into the deflected waves.

Is there an alternative method?

The alternative way to tap into black hole energy would include pulling out that energy in the shape of what they call Schwinger pairs—pairs of particles that spontaneously come into existence when there’s an electric field around.

If we kicked off with a black hole fully charged up, the electric field close to the event horizon could be so intense that it would spontaneously whip up an electron and a positron (kind of like an electron but with the opposite charge), as Mai clarified. If the black hole had a positive charge, the positron would get expelled from the black hole because of the repulsion. In theory, that runaway particle could then be gathered up as energy.

Mai mentioned he’s unsure if we’ll ever witness a battery like this in reality, but the whole theoretical exploration stemmed from scientists’ earlier endeavors to figure out how to extract energy from black holes on paper.

“We see the black hole as a place where quantum mechanics and gravity have to somehow get together,” Daniele Faccio, a physicist at the University of Glasgow who was not involved in the study, told Live Science. “By looking at them from the perspective of energy mining, we can understand a little more about what’s going on.”

Scientists thrilled by black hole’s twisted magnetic field

Light swirling at the edge of a faraway supermassive black hole might play a role in preventing matter from being devoured by this massive cosmic giant. M87*, the supermassive black hole, weighing in at about 6.5 billion times the mass of our sun, gained widespread recognition in 2019. The Event Horizon Telescope (EHT) snapped the first-ever image of the surroundings of a black hole, giving humanity a glimpse into the mysterious world of M87*.

In November, the folks from the EHT Collaboration, the ones who brought us that groundbreaking image, simulated how the electric fields of light twirl around the supermassive black hole, chilling about 54 million light-years away from us. This polarized light, with waves rocking on a single plane, brings along details about the magnetic field and the particles revved up to speeds close to the speed of light near the black hole.

Now, researchers propose that these magnetic fields might be preventing M87’s colossal black hole from having a feast. Instead, they might be sending this matter into space in the form of tightly focused (or parallel) jets that shoot out at nearly the speed of light. The ever-spinning light around M87*, by the way, is also called circular polarization.

“Circular polarization is the final signal we looked for in the EHT’s first observations of the M87 black hole, and it (the polarization) was by far the hardest to analyze,” Andrew Chael, study co-author and project coordinator at Princeton University, said in a statement. “These new results give us confidence that our picture of a strong magnetic field permeating the hot gas surrounding the black hole is the right one,” added Chael, an associate research scholar with the Princeton Gravity Initiative — which combines the university’s astrophysics, mathematics and physics departments to seek the nature of gravity.

Two years after dropping the picture of the supermassive black hole in M87, in 2021, the EHT Collaboration treated us to another jaw-dropping view. This fresh image unveiled, for the very first time, polarized light surrounding a black hole. (Polarized light stands out with a distinct orientation and brightness compared to unpolarized light.) The data from 2021 also spilled the beans on the direction of oscillating (vibrating) electric fields, giving us the initial clue that the magnetic fields around M87* are robust and well-organized.

Also Read: Galaxies like Milky Way might be rare in our cosmic neighborhood

Researchers used ALMA as the reference antenna

Next up, the scientists zoomed in using the Atacama Large Millimeter/submillimeter Array (ALMA) up there in Northern Chile. ALMA played a crucial role by acting as a reference antenna for the EHT, providing the necessary calibration. Situated in the Chilean desert, ALMA boasts 66 antennas, and its superpower is peering through cosmic dusty scenes, such as black holes, to hunt for longer wavelengths of light.

ALMA is one piece of the puzzle in the EHT’s network of radio telescopes scattered worldwide. When combined, they form a virtual instrument as big as Earth. This technique is also dubbed very long baseline interferometry, or VLBI.

The fresh examination of the ALMA data from 2017 reveals the way the electric fields of light twirl in a linear fashion, reinforcing the idea of the robust magnetic fields we saw in 2021. Through computer simulation, the EHT scientists propose that these mighty magnetic fields push against the matter moving toward M87*.

The magnetic fields also shoot out jets of matter from M87* at speeds close to the speed of light. This happens before the matter crosses the black hole’s event horizon—the point where nothing, not even light, can escape—and contributes to the already massive bulk of the black hole.

The researchers are still digging into the data, looking for more convincing signs of linear polarization. Hugo Messias, a co-author of the study and head of the VLBI team at ALMA, mentioned in the same statement that there’s still room for improvement in their work.

“This circularly polarized light that has now been detected is very faint, but in more recent years, EHT has been observing with more stations and improved sensitivity — meaning that the ongoing analysis will likely provide us with new tips on the secrets around M87*.”

The EHT Collaboration, credited as the united front in the latest discoveries, is essentially the lead author in the fresh findings. You can dive into the details in a paper published on Wednesday (Nov. 8) in the Astrophysical Journal.