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One of physicist Stephen Hawking’s most famous paradoxes may finally be solved: Black holes may in fact hang onto information about the massive stars that created them, new research indicates. 

This information may lurk in the radiation around black holes – colloquially known as “quantum hair” – and could, in theory, be retrieved to retell the origins of those black holes, the research suggests. 

These findings, published March 6 in the journal Physics Letters B. (opens in new tab) , may finally resolve a thorny problem that Hawking was working on in his last years. 

Related: Stephen Hawking’s final book says there’s ‘no possibility’ of God in our universe

According to Hawking’s work, radiation slowly “leaks” out of black holes in the form of thermal energy, which has come to be known as “Hawking radiation.” But because of its thermal nature, this radiation can’t carry information. That means that as black holes evaporate, they methodically destroy all information about the stars that created them. This is contrary to the laws of quantum mechanics, which say that information cannot be destroyed and that an object’s final state can reveal clues about its initial state. This problem has troubled cosmologists for decades and is known as the “Hawking information paradox.” 

“[This research] is the final nail in the coffin for the paradox because we now understand the exact physical phenomenon by which information escapes a decaying black hole,” lead study author Xavier Calmet (opens in new tab) , a professor of physics at the University of Sussex, told Live Science via email. He suggests a modification to Hawking radiation that makes it “non-thermal” and thus capable of carrying information with it away from the final fate of the black hole. 

Physicist Stephen Hawking in his office in 1989. (Image credit: Jean-Regis Rouston/Roger Viollet via Getty Images) The black hole problem

Black holes are objects so massive that nothing can escape the pull of their gravity, not even light. They form when enormous stars run out of fuel and collapse in on themselves.

In classical physics, black holes are “very simple objects,” Calmet said. “So simple that they can be characterized by three numbers: their mass, angular momentum, and electric charge.”

Famous physicist John Wheeler described this lack of distinguishing characteristics by saying “black holes have no hair.” But, Calmet explained, while the final black hole is very simple, the original star that birthed it is a complex astrophysical object, consisting of a complicated amalgam of protons, electrons, and neutrons which come together to form the elements that build the chemical composition of that star. 

While black holes carry no “memory” of the stars they once were, the rules of quantum physics say that information can’t simply be erased from the universe. In 1976, Hawking introduced a fly to this cosmic ointment by showing this information couldn’t dwell indefinitely within black holes sealed away from the outside universe either. Applying the rules of quantum mechanics to black holes, Hawking suggested they emit a type of thermal radiation, later called Hawking radiation. Over immense periods of time, the leaking of this radiation causes black holes to completely evaporate, leaving only a vacuum behind. In this way, information is irretrievably lost.

“This is however not allowed by quantum physics, which posits that the movie of this black hole’s ‘life’ could be rewound,” Calmet said. “Starting from the radiation we should be able to rebuild the original black hole and then eventually the star.”Finding the black hole’s ‘hair’

Along with his colleague Steve Hsu (opens in new tab) , a professor of theoretical physics at Michigan State University, Calmet has been working since 2021 to crack Hawking’s paradox. In a previous study, published in March 2022, the team argued that black holes do indeed have “quantum hair,” in the form of a unique quantum imprint in the gravitational fields that surround them

In their new research, the team reassessed Hawking’s 1976 calculations, but this time accounted for the effects of “quantum gravity”  —  the description of gravity according to the principles of quantum mechanics  —  something Hawking hadn’t done. Related stories— The 12 Strangest Objects in the Universe

— The 18 Biggest Unsolved Mysteries in Physics 

— 11 Fascinating Facts About Our Milky Way Galaxy 

“While these quantum gravitational corrections are minuscule, they are crucial for black hole evaporation,” Calmet said. “We were able to show that these effects modify Hawking radiation in such a way that this radiation becomes non-thermal. In other words, factoring in quantum gravity the radiation can contain information.”

While the quantum hair suggested in Calmetand Hsu’s previous work was an abstract mathematical concept, the team has now identified the exact physical phenomenon by which information escapes the black hole via Hawking radiation, and how it could be retrieved by an outside observer. This is currently not possible, as it would require an instrument sensitive enough to measure Hawking radiation, which currently is purely theoretical. 

Currently there is no real way for astrophysicists to measure the effect the researchers propose, as it is minuscule, Calmet acknowledged. Instead, he suggests one way to progress this theory would be by studying simulations of black holes in labs on Earth. The team’s mathematical modeling of Hawking radiation and black holes could prove invaluable in these simulations. 

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National Guard will begin carrying firearms in Washington DC, official says

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National Guard will begin carrying firearms in Washington DC, official says

National Guard troops deployed to Washington DC in an effort to mitigate crime will begin carrying firearms, an official has said.

Defence secretary Pete Hegseth ordered the authorisation of roughly 2,000 National Guard troops to begin carrying weapons.

The majority of the guard members will carry M17 pistols, their service-issued weapons, while a small number will be armed with M4 rifles, reports Sky’s US partner organisation, NBC News.

The troops are authorised to use their weapons for self-protection.

A White House official told NBC News that despite being armed, as of Saturday night, the National Guard troops in DC are not making arrests, and will continue to work on protecting federal assets.

The troops were largely deployed from outside the state and were framed by President Trump as a concerted effort to tackle crime and homelessness in the nation’s capital.

Such deployments are not common, and are typically used in response natural disasters or civil unrest.

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Democrats have bashed the deployment as partisan in nature, accusing Mr Trump of trying to exert his presidential authority through scare tactics and said his primary targets have been cities with black leadership.

Armed members of the South Carolina National Guard patrol outside of Union Station. Pic: AP
Image:
Armed members of the South Carolina National Guard patrol outside of Union Station. Pic: AP

Pentagon plans to deploy US army to Chicago

Yesterday it was reported that the Pentagon was drafting plans to deploy the US army in Chicago, the largest city in the state.

The governor of Illinois then accused Mr Trump of “attempting to manufacture a crisis” and “abusing his power to distract from the pain he is causing working families”.

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Officials familiar with the proposals told the Washington Post that several options were being weighed up by the US defence department, including mobilising thousands of National Guard troops in Chicago as early as September.

Mr Trump had told reporters on Friday that “Chicago is a mess”, before attacking the city’s mayor, Brandon Johnson, and hinting “we’ll straighten that one out probably next”.

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Flesh-eating screwworm parasite detected in person in US for first time

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Flesh-eating screwworm parasite detected in person in US for first time

A case of the flesh-eating screwworm parasite has been detected in a person in the United States for the first time.

The parasitic flies eat cattle and other warm-blooded animals alive, with an outbreak beginning in Central America and southern Mexico late last year.

It is ultimately fatal if left untreated.

The case in the US was identified in a person from Maryland who had travelled from Guatemala.

Beth Thompson, South Dakota’s state veterinarian, told Reuters on Sunday that she was notified of the case within the
last week.

A Maryland state government official also confirmed the case.

The person was treated and prevention measures were implemented, Reuters reports.

The Centres for Disease Control and Prevention (CDC) and the Maryland Department of Health did not immediately respond to requests for comment.

What is screwworm?

The female screwworm fly lays eggs in the wounds of warm-blooded animals and once hatched, hundreds of screwworm larvae use their sharp mouths to burrow through living flesh.

It can be devastating in cattle and wildlife, and has also been known to infect humans.

Treatment is onerous, and involves removing hundreds of larvae and thoroughly disinfecting wounds. They are largely survivable if treated early enough.

The confirmed case is likely to rattle the beef and cattle futures market, which has seen record-high prices because of tight supplies.

The US typically imports more than a million cattle from Mexico each year to process into beef. The screwworm outbreak could cost Texas – the biggest cattle-producing state – $1.8bn (£1.3bn) in livestock deaths, labour costs and medication
expenses.

A view shows a calf after being sprayed with a disinfectant spray to prevent screwworm. Pic: Reuters
Image:
A view shows a calf after being sprayed with a disinfectant spray to prevent screwworm. Pic: Reuters

The United States Department of Agriculture (USDA) has set traps and sent mounted officers along the border, but it has faced criticism from some cattle producers and market analysts for not acting faster to pursue increased fly production via a sterile fly facility.

What is a sterile fly facility?

The case also comes just one week after the US agriculture secretary, Brooke Rollins, travelled to Texas to announce plans to build a sterile fly facility there in a bid to combat the pest. Ms Rollins had pledged repeatedly to keep screwworm out of the country.

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A sterile fly facility produces a large number of male flies and sterilises them – these males are then released to mate with wild female insects, which collapses the wild population over time. This method eradicated screwworm from the US in the 1960s.

Mexico has also taken efforts to limit the spread of the pest, which can kill livestock within weeks if not treated. It had started to build a $51m sterile fly production facility.

The USDA has previously said 500 million flies would need to be released weekly to push the fly back to the Darien Gap, the stretch of rainforest between Panama and Colombia.

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UK

Urgent letter to home secretary over violence against women and girls strategy – as it omits child abuse

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Urgent letter to home secretary over violence against women and girls strategy - as it omits child abuse

Ten child protection organisations have written an urgent letter to the home secretary expressing concern about the omission of child sexual abuse from the government’s violence against women and girls strategy, following a Sky News report. 

Groups including the NSPCC, Barnardo’s and The Children’s Society wrote to Yvette Cooper to say that violence against women and girls (VAWG) and child sexual abuse are “inherently and deeply connected”, suggesting any “serious strategy” to address VAWG needs to focus on child sexual abuse and exploitation.

The letter comes after Sky News revealed an internal Home Office document, titled Our draft definition of VAWG, which said that child sexual abuse and exploitation is not “explicitly within the scope” of their strategy, due to be published in September.

Poppy Eyre when she was four years old
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Poppy Eyre when she was four years old

Responding to Sky News’ original report, Poppy Eyre, who was sexually abused and raped by her grandfather when she was four, said: “VAWG is – violence against women and girls. If you take child sexual abuse out of it, where are the girls?”

The Centre of Expertise on Child Sexual Abuse, which is funded by the Home Office and a signatory to the letter, estimates 500,000 children in England and Wales are sexually abused every year.

The NSPCC “welcome” the government’s pledge to halve VAWG in a decade, but is “worried that if they are going to fulfil this commitment, the strategy absolutely has to include clear deliverable objectives to combat child sexual abuse and exploitation too”, the head of policy, Anna Edmundson, told Sky News.

Poppy is a survivor of child sexual abuse
Image:
Poppy is a survivor of child sexual abuse

She warned the government “will miss a golden opportunity” and the needs of thousands of girls will be “overlooked” if child sexual abuse and exploitation is not “at the heart of its flagship strategy”.

The government insists the VAWG programme will include action to tackle child sexual abuse, but says it also wants to create a distinctive plan to “ensure those crimes get the specialist response they demand”.

“My message to the government is that if you’re going to make child sexual abuse a separate thing, we need it now,” Poppy told Sky News.

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Rape Crisis, which is one of the largest organisations providing support to women in England and Wales, shares these concerns.

It wants plans to tackle child sexual abuse to be part of the strategy, and not to sit outside it.

“If a violence against women and girls strategy doesn’t include sexual violence towards girls, then it runs the risk of being a strategy for addressing some violence towards some females, but not all,” chief executive Ciara Bergman said.

A Home Office spokesperson said the government is “working tirelessly to tackle the appalling crimes of violence against women and girls and child sexual exploitation and abuse, as part of our Safer Streets mission”.

“We are already investing in new programmes and introducing landmark laws to overhaul the policing and criminal justice response to these crimes, as well as acting on the recommendations of Baroness Casey’s review into group-based Child Sexual Exploitation, and the Independent Inquiry into Child Sexual Abuse,” they added.

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