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.
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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
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“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.
Britons have been warned of long delays on their Easter getaways with more than 14 million journeys expected on the roads, airports prepared for a record number of passengers, and engineering works on key rail services.
The RAC warned that journeys on popular routes could take twice as long as usual, as the bank holiday weekend leads into a two-week holiday for many schools.
Trains are also set to be stopped as Network Rail carries out engineering works on the West Coast Main Line – which stretches from the capital to Scotland – between London Euston and Milton Keynes.
And at least three major airports have said that the coming days will be their busiest ever Easter weekend.
Bristol, Newcastle and Edinburgh have told The Independent they predict a record number of passengers from Good Friday to Easter Monday, with routes to Geneva tipped to be extremely busy.
Around two million Britons are expected to fly away over the holiday weekend, with Bristol predicting 30,000 holiday-goers on Easter Sunday alone.
Airports will stay busy over the school holidays, with Luton expecting to see around 38 passengers a minute on 5 April.
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On Sunday 7 April, Gatwick and Southampton are set to see their busiest days.
No ‘good time’ for rail works
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The West Coast Main Line will be closed between Good Friday and Easter Monday, with disruption to rail services also expected in Glasgow and Huddersfield.
Laurence Bowman, Network Rail’s network strategy director, said earlier this week that there is “never a good time to do the work we need to do”, but explained that a lower number of commuters over the bank holiday weekend gives them “the opportunity to do major work we couldn’t do in a normal weekend”.
“We’ve got 493 different pieces of work taking place this Easter, most happening overnight,” he added, “including laying over 8,000 metres of new rail and putting down over 40,000 tonnes of new ballast to support the tracks.”
‘Carmageddon’
RAC spokesperson Alice Simpson warned it “could be carmageddon” over Easter and said heavy traffic and “lengthy queues can be expected along routes to the usual hotspots”.
Inrix transportation analyst Bob Pishue also said that “drivers should be prepared for longer journeys than normal throughout the entire weekend”.
A survey commissioned by the RAC and Inrix found that 2.6 million journeys are planned on Good Friday, with around 2.3 million trips expected for both Easter Saturday and Sunday.
Another two million trips are expected on Thursday and Easter Monday, and a further 3.3 million journeys are due with no clear starting date, making for a total of around 14.5 million journeys.
Inrix predicted that the worst of the traffic is expected between 2pm and 7pm on Thursday when holiday journeys mix with regular commutes.
It added that the busiest route is set to be the western section of the M25 between the M23 for Gatwick and the M1 for Hertfordshire where journeys from 4pm are tipped to take more than two hours, more than twice as long as usual.
The M5 southbound between Bristol and Taunton, and the M3 between the M25 and the south coast are also likely to be congested, according to Inrix, with estimated journey times more than double what they normally are.
The survey, from research company Find Out Now, polled 2,136 UK adults.
The Met Office said the alert applies from 7am until 6pm on Thursday and extends in a band from locations such as St Ives and Penzance in the South West across to Brighton.
Sky News weather producer Christopher England also said: “It’ll stay mostly unsettled into next week, with further heavy showers or longer spells of rain, and 70mph gusts near Channel coasts, thanks to the Spanish-named Storm Nelson.”
More delays in Dover
Meanwhile, Britons taking ferries should be able to embark without much issue, with the exception of the Port of Dover where French border staff check passports before leaving the UK.
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From 2023: ‘Severe’ delays for Easter travel
Around 20,000 cars are expected to travel through Dover’s port between Thursday and Easter. A Coach Processing Facility has been set up in the Western Docks for Thursday and Saturday in a bid to ease travel.
Coach passengers and motorists will be processed away from the main port, and then moved to the Eastern Port for a quick passport check, before embarking on their ferry journey.
THE HAGUE, NETHERLANDS – MARCH 23:Dutch Prime Minister Mark Rutte meets with the President of the People’s Republic of China Xi Jinping at the Catshuis March 23, 2014 in The Hague, Netherlands. (Photo by Valerie Kuypers-Pool/Getty Images
China’s technological progress cannot be stopped, Chinese President Xi Jinping told Dutch Prime Minister Mark Rutte when they met in Beijing Wednesday for talks on areas such as the critical semiconductor industry.
“The Chinese people also have legitimate development rights, and no force can stop the pace of China’s scientific and technological progress,” said Xi, according to Xinhua News Agency.
Xi said China will “continue to pursue a win-win approach.”
Relations between China and the Netherlands have been strained since the the Netherlands, together with the U.S., blocked exports of advanced chip technology to China over concerns they could be used for military purposes.
Semiconductor chips are critical components which can be found in everything from smartphones to automobiles.
Such EUV lithography machines are crucial for chip manufacturing and are used by companies like Taiwan’s TSMC to make the smallest and most sophisticated chips.
In January, the Netherlands barred ASML from exporting some of its deep ultraviolet lithography systems to China, which are used to make slightly less advanced chips.
Beijing slammed the Dutch government’s move, urging the Netherlands to “uphold an objective and fair position and market principles” and “protect the shared interests” of the two countries and their companies.
“Creating scientific and technological barriers and severing industrial and supply chains will only lead to division and confrontation,” Xi said Wednesday, according to Xinhua state media.
He said cooperation is the only way and added that “decoupling and breaking the chain” is not an option.
Xi said China is ready to continue dialogue with the Netherlands and urged the Dutch side to “provide a fair and transparent business environment for Chinese enterprises.”
According to Reuters, Rutte said Wednesday the Netherlands tried to ensure that export restrictions, when related to semiconductor industry and companies like ASML, are never aimed at one country. “We always try to make sure the impact is limited,” he was quoted as saying.
Chinese state media reported that Rutte responded by saying decoupling is not a policy choice for the Dutch government either, “since any act undermining China’s development interests will only boomerang.”
A pilot on board the cargo ship that crashed into the Baltimore bridge tried to swing it clear of a collision by dropping its port anchor to pivot it away, authorities said.
The pilot and a second on board at the time of collision will be interviewed by the National Transportation Safety Board (NTSB) today.
The US Coast Guard also confirmed that the container ship’s engines had undergone routine maintenance while in the Baltimore port.
Information recovered from the ship’s voyage data recorder (VDR) showed power failed for just one minute and three seconds as it approached the structure, but that was enough for the collision to become seemingly unavoidable .
The recorder, which officials noted is “very basic” when compared to those on aircraft, stopped picking up sensor data during the outage but did record audio of the pilot giving steering commands and rudder orders and had enough information to create a timeline leading up to impact:
00:39:00 VDR recorded ship’s departure from Seagirt Marine Terminal 01:07 ship had entered the Fort McHenry Channel 01:24 ship was on a heading underway on a true heading of approx 141 degrees at a speed of 8 knots / 9.2mph 01:24:59 Numerous audible alarms recorded on ships bridge audio – at same time, the VDR stopped recording sensor data, but continued to record audio using redundant power source 01:26:02 VDR sensor data recording resumed. Steering commands and rudder orders were recorded on the audio during this time 01:26:39 Pilot made general VHF call for tugs in the vicinity to assist. At the same time, the power of association dispatcher phoned the Maryland Transport Authority (MDTA) duty officer regarding the blackout 01:27:04 Pilot ordered the DALI to drop the port anchor and ordered additional steering commands 01:27:25 Pilot issued a radio call over the VHF radio reporting the DALI had lost all power and was heading towards the bridge. Around this time MDTA data shows the following also occurred: the duty officer radioed to their units that were already on scene due to construction on the bridge – one on each side of the bridge – and ordered them to close the traffic on the bridge. All lanes were then shut down by MDTA 01:29:00 ship’s speed was just under 7 knots / 8pmh and from 0129:00 to 01:29:33 the ship’s audio recorded the collision of the bridge 01:29:39 Pilot reported the bridge down over the audio to the coast guard
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An official also said that the Key Bridge was fracture-critical, which means “if a member fails that would likely cause a portion of, or the entire bridge, to collapse, there’s no redundancy”.
NTSB board chair Jennifer Homendy also noted that according to the Federal Highway Administration, there are close to 17,500 fracture-critical bridges in the US.
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She added: “It’s pretty devastating, certainly, seeing not just what’s going on with the cargo containers, but just looking at what was a bridge span – three bridge spans that is pretty much gone. It’s just utter devastation.”
The men recovered have been identified as Alejandro Hernandez Fuentes, 35, who was from Mexico and lived in Baltimore, and Dorlian Ronial Castillo Cabrera, 26, who was from Guatemala and lived in Dundalk, Maryland.
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Earlier on Wednesday, the first two missing construction workers were named as Miguel Luna, a 49-year-old from El Salvador, and Maynard Sandoval, a 37-year-old father-of-two. Two other people are also still missing – all are presumed dead.
The recovery mission is now a salvage operation as it is no longer safe for divers to navigate or operate around the debris and concrete in the port.
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Baltimore: Second missing man named
The victims, who were from Mexico, Honduras, El Salvador and Guatemala, were part of a crew filling potholes on the bridge’s road surface at the time of the collapse.
The Key Bridge carried the Interstate 695 highway over the Patapsco River southeast of the Baltimore metropolitan area.
US President Joe Biden has promised that he will visit Baltimore “as soon as possible”, adding that the federal government will cover the “full cost” of rebuilding the bridge – which experts say could be over $600m (£474m).
Its main section spanned 1,200 feet and was one of the longest continuous truss bridges in the world upon its completion, according to the National Steel Bridge Alliance.
The Dali was previously involved in a minor incident when it hit a quay at the Port of Antwerp in Belgium in 2016, where it was damaged, according to Vessel Finder and maritime accident site Shipwrecklog.
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