Stephen Hawking now thinks "there are no black holes"

The physicist, whose pioneering work on black holes in the 1970s made him a household name, has proposed a radical fudge to try and resolve a baffling paradox.

For a scientist whose career was made by his work on black holes, it might seem a little confusing to read that Stephen Hawking now thinks that they don’t exist. But that’s what “Information Preservation and Weather Forecasting for Black Holes”, the study Hawking published last week on arXiv, says: “there are no black holes”.

While this might seem surprising - after all, there’s a huge amount of (indirect) evidence that black holes exist, including a massive one several million times the mass of our Sun at the centre of the Milky Way - it’s really not. It’s Hawking’s latest attempt to solve a paradox that he, and other astrophysicists, have been grappling with for a couple of years.

So what’s he talking about? Here’s the background: black holes are objects which are so massive, with such strong gravity, that even light can’t escape. The distance from the black hole, beyond which nothing gets out, is the event horizon. However, Hawking made his name in the 1970s when he published a paper showing that black holes don’t just suck stuff up, endlessly - they spew out a beam of so-called “Hawking radiation” as they absorb other matter. That means black holes actually lose mass over time, eventually whittling away to nothing.

Black holes are frustrating, though, because their extreme gravity exposes the major inadequacy in our current scientific understanding of the universe - we don’t know how to reconcile quantum mechanics and general relativity. With general relativity, we can make accurate predictions about objects with certainty, but on the tiny scale of quantum mechanics it’s only possible to talk about the behaviour of objects in terms of probability. When we do the maths on what happens to things that fall into black holes, using relativity gives results that break quantum mechanics; the same goes vice versa.

One of the key things about quantum mechanics is that it tells us information can’t be destroyed - that is, if you measure the radiation given off by a black hole, you should be able to build up a picture of what matter fell into the hole to create it. However, if general relativity holds, and nothing can escape from inside the event horizon, then that should apply to that quantum information - any radiation that’s coming out is, Hawking showed, random. It’s the black hole “information paradox”. Either give up quantum mechanics, or accept that information can die.

Hawking was in the “information can die” camp, until 2004, when it became clear - thanks to string theory - that quantum mechanics held up (and there’s an excellent in-depth explanation of this in Nature that explores this story more fully if interested). There was just one problem - nobody could work out *how* information was getting out of black holes, even if it was happening mathematically.

And, just in case this wasn’t all entirely confusing, it turns out that our best post-2004 theory about what’s been going on gives rise to an entirely new paradox - the “firewall”.

It’s to do with quantum entanglement, where two particles are created that are identical on the quantum level. The way it works isn’t exactly clear yet - it could be something to do with string theory and wormholes - but it means that measuring the properties of one particle will give readings that mirror those found on its entangled particle. It might lead to teleportation technology, but scientists aren’t sure yet.

Joseph Polchinski from the Kavli Institute for Theoretical Physics in Santa Barbara, California published a paper in 2012 that worked out the information paradox could be solved if Hawking radiation was quantum entangled with the stuff falling in. But, due to the limitations of entanglement, if this is true, that would mean that at the event horizon a massive amount of energy was given off by particles entering and leaving.

Hence “firewall” - anything crossing the event horizon would be burnt to a crisp. And even though most scientists, including Polchinski, thought this couldn’t possibly be right - it completely contradicts a lot of the stuff underlying general relativity, for example - nobody’s yet managed to disprove it.

The choice for physicists, once again, was to: a) accept the firewall, and throw out general relativity, or b) accept that information dies in black holes, and quantum mechanics is wrong.

Still with me? Here’s where Hawking’s latest paper comes in.

(That title - “Information Preservation and Weather Forecasting for Black Holes” - might make some more sense too, hopefully.)

Hawking’s proposed solution, building on an idea first floated in 2005, is that the event horizon isn’t as defined as we’ve come to imagine it. He instead proposes something called an “apparent horizon”, which light and other stuff can escape from:

"The absence of event horizons mean that there are no black holes - in the sense of regimes from which light can't escape to infinnity. There are however apparent horizons which persist for a period of time."

Black holes should be treated more like massive galactic washing machines. Stuff falls in and starts getting tossed around, mixed up with other stuff in there, and only eventually is allowed to escape out again when ready. This happens because the quantum effects around a black hole, like weather on Earth, churn so violently and unpredictably that it’s just impossible to either predict the position of an event horizon or expect uniform effects for stuff crossing it. While the theoretical basis, that information is preserved, remains, in practice it's so difficult as to be impractical.

It’s a fudge of an idea, which tries to have its general relativity and quantum mechanics cakes, and eat them, too. Possible weaknesses, as Nature points out, are that it could imply that escaping from black holes is easier than it is in reality. It could also be the apparent horizons are just as much of a firewall as the traditional conception of an event horizon. Hawking's peers have yet to have a go at assessing his idea, so we'll have to wait to see whether the idea has merit - or whether it merely gives rise to yet more paradoxes.

Hawking in Cambridge, September 2013. (Photo: Getty)

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

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How hackers held the NHS to ransom

NHS staff found their computer screens repleaced by a padlock and a demand for money. Eerily, a junior doctor warned about such an attack days earlier. 

On Friday, doctors at Whipps Cross Hospital, east London, logged into their computers, but a strange red screen popped up. Next to a giant padlock, a message said the files on the computer had been encrypted, and would be lost forever unless $300 was sent to a Bitcoin account – a virtual currency that cannot be traced. The price doubled if the money wasn’t sent within six days. Digital clocks were counting down the time.

It was soon revealed Barts Health Trust, which runs the hospital, had been hit by ransomware, a type of malicious software that hijacks computer systems until money is paid. It was one of 48 trusts in England and 13 in Scotland affected, as well as a handful of GP practices. News reports soon broke of companies in other countries hit. It affected 200,000 victims in 150 countries, according to Europol. This included the Russian Interior Ministry, Fedex, Nissan, Vodafone and Telefonica. It is thought to be the biggest outbreak of ransomware in history.

Trusts worked all through the weekend and are now back to business as usual. But the attack revealed how easy it is to bring a hospital to its knees. Patients are rightly questioning if their medical records are safe. Others fear hackers may strike again and attack other vital systems. Defence minister Michael Fallon was forced to confirm that the Trident nuclear submarines could not be hacked.

So how did this happen? The virus, called WannaCry or WannaDecrypt0r, was an old piece of ransomware that had gained a superpower. It had been combined with a tool called EternalBlue which was developed by US National Security Agency spies and dumped on the dark web by a criminal group called Shadow Brokers. Computers become infected with ransomware when somebody clicks on a dodgy link or downloads a booby-trapped PDF, but normally another person has to be fooled for it to harm a different computer. EternalBlue meant the virus could cascade between machines within a network. It could copy itself over and over, moving from one vulnerable computer to the next, spreading like the plague. Experts cannot trace who caused it, whether a criminal gang or just one person in their bedroom hitting "send".

Like a real virus, it had to be quarantined. Trusts had to shut down computers and scan them to make sure they were bug-free. Doctors – not used to writing anything but their signature – had to go back to pen and paper. But no computers meant they couldn’t access appointments, referral letters, blood tests results or X-rays. In some hospitals computer systems controlled the phones and doors. Many declared a major incident, flagging up that they needed help. In Barts Health NHS Trust, ambulances were directed away from three A&E departments and non-urgent operations were cancelled.

The tragedy is that trusts had been warned of such an attack. Dr Krishna Chinthapalli, a junior doctor in London, wrote an eerily premonitory piece in the British Medical Journal just two days earlier telling hospitals they were vulnerable to ransomware hits. Such attacks had increased fourfold between 2015 and 2016, he said, with the money being paid to the criminals increased to $1bn, according to the FBI. NHS trusts had been hit before. A third reported a ransomware attack last year, with Imperial College London NHS Trust hit 19 times. None admitted to paying the ransom.

Hospitals had even been warned of this exact virus. It exploited a vulnerability in Microsoft Windows operating systems – but Microsoft had been tipped off about it and raised the red flag in March. It issued a patch – an update which would fix it and stop systems being breached this way. But this patch only worked for its latest operating systems. Around 5 per cent of NHS devices are still running the ancient Windows XP, the equivalent of a three-wheeled car. Microsoft said it would no longer create updates for it two years ago, rendering it obsolete.

There are many reasons why systems weren’t updated. Labour and the Lib Dems were quick to blame the attack on lack of Tory funding for the NHS. It is clear cost was an issue. Speaking on BBC Radio 4’s PM programme on Saturday, ex-chief of NHS Digital Kingsley Manning estimated it would take £100m a year to update systems and protect trusts against cyber attacks. Even if that money was granted, there is no guarantee cash-strapped trusts would ringfence it for IT; they may use it to plug holes elsewhere.

Yet even with the money to do so updating systems and applying patches in hospitals is genuinely tricky. There is no NHS-wide computer system – each trust has its own mix of software, evolved due to historical quirk. New software or machines may be coded with specific instructions to help them run. Changing the operating system could stop them working – affecting patient care. While other organisations might have time to do updates, hospital systems have to be up and running 24 hours a day, seven days a week. In small hospitals, it’s a man in a van manually updating each computer.

Some experts believe these are just excuses; that good digital hygiene kept most trusts in the UK safe. "You fix vulnerabilities in computers like you wash your hands after going to the toilet," said Professor Ross Anderson, a security engineering expert at Cambridge University. "If you don't, and patients die, excuses don't work and blame shifting must not be tolerated."

It is not known yet if any patients have died as a result of the attack, but it certainly raised fears about the safety of sensitive medical records. This particular virus got into computer files and encrypted them – turning them into gooble-de-gook and locking doctors out. Systems were breached but there have been no reports of records being extracted. Yet the scale of this attack raises fears in future the NHS could be targeted for the confidential data it holds. "If it’s vulnerable to ransomware in this way, it could be vulnerable to other attacks," said Professor Alan Woodward security expert at the University of Surrey's department of computing.

In the US, there have been examples where ransomware attacks have led to patient data being sucked out, he said. The motivation is not to embarrass people with piles or "out" women who have had an abortion, but because medical information is lucrative. It can be sold to criminals for at least $10, a price 10 times higher than can be earned by selling credit card details. Dossiers with personal identification information – known as "fullz" on the dark web – help crooks commit fraud and carry out scams. The more personal details a conman knows about you the more likely you are to fall for their hustle.

Hospital data is backed up at least hourly and three copies are kept, one offsite, so it is unlikely any medical records or significant amounts of data will have been lost – although the hack will cost the NHS millions in disruption. A British analyst, who tweets under the name Malware Tech, became an unlikely hero after accidentally finding a killswitch to stop the virus replicating. He registered a website, whose presence signalled to the virus it should stop. Yet he admits that a simple tweak of the code would create a new worm able to infect computers.

Experts warn this event could trigger a spate of copycat attacks. Hacker may turn their eyes to other public services. Dr Brian Gladman, a retired Ministry of Defence director, and ex-director of security at Nato, points out that our entire infrastructure, from the national grid, food distribution channels to the railways rely on computer systems. We now face an arms race – and criminals only have to get lucky once.

"We’re going to get more attacks and more attacks and it’s going to go on," he said. "We’ve got to pay more attention to this."

Madlen Davies is a health and science reporter at The Bureau of Investigative Journalism. She tweets @madlendavies.

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