For the last seven decades, astrophysicists have theorized the existence of “kugelblitze,” black holes caused by extremely high concentrations of light.

These special black holes, they speculated, might be linked to astronomical phenomena such as dark matter, and have even been suggested as the power source of hypothetical spaceship engines in the far future.

However, new theoretical physics research by a team of researchers at the University of Waterloo and Universidad Complutense de Madrid demonstrates that kugelblitze are impossible in our current universe. Their research, titled “No black holes from light,” is published on the arXiv preprint server and is forthcoming in Physical Review Letters.

“The most commonly known black holes are those caused by enormous concentrations of regular matter collapsing under its own gravity,” said Eduardo Martín-Martínez, who is a professor of applied mathematics and mathematical physics and affiliate of the Perimeter Institute for Theoretical Physics.

“Because, in Einstein’s theory of general relativity, any kind of energy curves space-time, it has been long speculated that an enormous concentration of energy in the form of light might lead to a similar collapse. However, this prediction was made without considering quantum effects.”

The team built a mathematical model, taking into account quantum effects, that demonstrated that the concentration of light required to create kugelblitze would be tens of orders of magnitude greater than that observed in quasars, the brightest objects in our universe.

“Long before you could reach that intensity of light, certain quantum effects would occur first,” said José Polo-Gómez, a Ph.D. candidate in applied mathematics and quantum information. “That strong of a concentration of light would lead to the spontaneous creation of particles like electron-positron pairs, which would move very quickly away from the area.”

Though the conditions necessary to achieve such an effect are impossible to test on earth using current technology, the team can be confident in the accuracy of their predictions because they rely on the same mathematical and scientific principles that power positron emission tomography (PET) scans.

“A way to understand this phenomenon is to think of the annihilation of matter and antimatter, like what happens during PET scans. Electrons, and their antiparticles (positrons) can annihilate each other and disintegrate into pairs of photons, or light ‘particles,'” Martín-Martínez said.

“Our results are a consequence of the phenomenon called ‘vacuum polarization’ and the Schwinger effect, and while explaining them in a few words can be challenging, a helpful way of thinking about it is this: The phenomenon we’ve predicted that would prevent the creation of black holes from light is in many ways like the opposite of the matter-antimatter disintegration phenomenon that happens in a PET scan. When there is a large concentration of photons they can disintegrate into electron-positron pairs, which are quickly scattered away taking the energy with them and preventing the gravitational collapse.”

While the impossibility of kugelblitze may be disappointing for astrophysicists, the discovery is an important achievement in the kind of fundamental physics research enabled by the partnership between applied mathematics, the Perimeter Institute, and the Institute for Quantum Computing at Waterloo.

“While these discoveries may not have known applications right now, we are laying the groundwork for our descendants’ technological innovations,” said Polo-Gómez. “The science behind PET scan machines was once just as theoretical, and now there’s one in every hospital.”

How bad for your health is space travel? Answering this question will be crucial not just for astronauts aiming to go to Mars, but for a booming space tourism industry planning to blast anyone who can afford it into orbit.

In what has been billed as the most comprehensive look yet at the health effects of space, dozens of papers were published on Tuesday using new data from four SpaceX tourists onboard the first all-civilian orbital flight in 2021.

Researchers from more than 100 institutions across the world sifted through the data to demonstrate that human bodies change in a variety of ways once they reach space—but most go back to normal within months of returning to Earth.

Our bodies are put under a huge amount of stress while in space, from being blasted with radiation to the disorientating effect of weightlessness.

By studying astronauts, researchers have known for decades that space flight can cause health issues such as loss of bone mass, as well as heart, eyesight and kidney problems.

Fewer than 700 people have ever traveled into space, meaning that the sample size is small—and governments can be reticent when it comes to sharing all their findings.

However, the four American tourists who spent three days in space during the Inspiration4 mission were happy to see their data made public.

The early results, which were compared to 64 other astronauts, were published in Nature journals on Tuesday.

When people are in space, they undergo changes to their blood, heart, skin, proteins, kidneys, genes, mitochondria, telomeres, cytokines and other health indicators, the researchers found.

But around 95 percent of their health markers returned to their previous level within three months.

‘I love my space scar’

The “big take-home” message is that people mostly make a rapid recovery after space flight, said one of the main study authors, Christopher Mason from Weill Cornell Medicine.

Mason told journalists he hoped the “most in-depth examination we’ve ever had of a crew” would help scientists understand what drugs or measures will be needed in the future to help protect people blasting off into space.

The Inspiration4 mission, financed by its billionaire captain Jared Isaacman, had the stated goal of demonstrating that space is accessible to people who have not spent years training for the feat.

To do so, the four civilian astronauts received a huge number of medical tests.

“I love my space scar,” nurse Hayley Arceneaux said of the lingering mark from a skin biopsy. She was just 29 when she went into space.

One study found that the telomeres—caps similar to those on shoelaces which protect the ends of chromosomes from fraying—of all four subjects dramatically lengthened when they arrived in space.

But their telomeres all shrunk back to near their original length within months of them returning to Earth.

Because telomeres also lengthen as people age, finding a way to address this problem could help “us mere Earthlings” in the never-ending fight against aging, said Colorado State University’s Susan Bailey.

It even could lead to anti-aging products such as “telomerase-infused face cream”, the study author speculated.

Safe mission to Mars?

Looking at the data so far, “there’s no reason we shouldn’t be able to safely get to Mars and back,” Mason said.

“You probably wouldn’t take multiple trips because it’s a lot of radiation,” he added.

One of the studies found that mice exposed to radiation equivalent to 2.5 years in space suffered permanent kidney damage.

“If we don’t develop new ways to protect the kidneys, I’d say that while an astronaut could make it to Mars they might need dialysis on the way back,” lead study author Keith Siew of the London Tubular Centre said in a statement.

But Mason emphasized that the research was “really mostly good news”.

“I think it bodes well for people who think: maybe I’ll go to space in six months,” he said.

While there was not enough data to say anything definitive, female astronauts seemed to be more tolerant of the stress of spaceflight, he added.

“It may be driven just by the fact that women have to give child birth,” meaning their bodies are more used to major changes, Mason said.

© 2024 AFP