Think that everything in a black hole gets swallowed up, never to be seen again? Well, you're half right

What happens to the information in a black hole once it disappears? Stephen Hawking thought he knew, betted on it, and lost.

Young people? Nothing but trouble. If you don’t believe the politicians, just look at physicists’ current anguish over the question of what is lost when stuff falls into a black hole. We are now in the middle of a huge crisis of confidence, just because the kids couldn’t keep their ideas to themselves.
 
If you think that stuff in a black hole just gets swallowed up, never to be seen again, you’re half right. The stuff is indeed gone. Yet the information about the stuff can’t be. In the 1970s, a young Stephen Hawking showed that, due to a quirk of quantum theory, black holes don’t just swallow; they also spit. A trail of particles is emitted from a black hole over its lifetime. As a result, the black hole eventually loses so much energy that it evaporates and disappears from the universe. According to Hawking’s theory, those particles contain no information of any kind, so the original information is lost once the black hole disappears.
 
However, a fundamental law of physics states that information can’t be destroyed. In 1997, John Preskill of the California Institute of Technology was so confident that Hawking must be wrong that the pair entered into a bet. That year, a young theorist called Juan Maldacena showed that, as stuff fell in, the information could be caught on the “event horizon”, the spherical surface of a black hole. With the information residing on the event horizon, it isn’t erased from the universe and might eventually leak back out.
 
Maldacena’s work was convincing enough for Hawking to concede. In 2004, he bought Preskill a baseball encyclopaedia (for reasons we won’t go into here) and the bet was considered settled.
 
Then, in 2010, along came the vibrant young mind of Mark Van Raamsdonk. His work has led to the new debate over the “cosmic firewall”. For information on the event horizon to leak back into the universe, there has to be a layer of ultra-high-energy particles – a firewall – just inside the event horizon. Each particle taking information from the event horizon has what Albert Einstein once termed a “spooky” link with a particle in the firewall. The link is called “entanglement” and it means that you can’t fully describe one of the particles unless you have information that resides in the other.
 
The problem is, the nature of Hawking’s original result shows that the particle on the outside of the event horizon also has to be entangled with another particle, one that carried away a little information from the black hole some time in the past. And a single particle can’t share that kind of entanglement with two others. So Maldacena’s idea doesn’t work. The best solution anyone can come up with involves another entanglement, this time between the particle inside the firewall and the particle that left the black hole all that time ago. That particular spooky link resolves the problem because those two entangled particles are actually one and the same.
 
It’s a classic Shakespearean twist. The whole problem has been a case of mistaken identity: the cosmic firewall story is the Twelfth Night of cosmology. However, most physicists don’t like this ending. Resolving all these entanglements stretches credulity too far, they say. The resolution they prefer is to acknowledge that this whole shebang exposes a gaping hole in our understanding of the universe. Maybe, they say, we need to start again.
 
While they scratch their heads and wonder what to do, Hawking could justifiably ask for his encyclopaedia back. If Preskill has any sense of how to play the foiled schemer, he’ll reluctantly hand it over while muttering something about those pesky kids. 
 
Michael Brooks’s “The Secret Anarchy of Science” is published by Profile Books (£7.99) 
In 1997 Hakwing made a bet with John Preskill of the California Institute of Technology - and lost. Photograph: Andrew Burman/Evevine/Contrasto.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 02 September 2013 issue of the New Statesman, Syria: The west humiliated

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Politicians: it's no longer OK to know nothing about technology

It’s bad enough to joke about not being "techy"; it's worse to back a piece of legislation from a position of ignorance. 

Earlier this week, facing down a 600-strong battalion of London’s tech sector at a mayoral hustings in Stratford, Zac Goldsmith opened his five minute pitch with his characteristic charm. “I’m not very techy!” he exclaimed. “I understand coding about as well as Swahili!”

Pointless jibe at a foreign language aside, this was an ill-chosen way to begin his address - especially considering that the rest of his speech showed he was reasonably well-briefed on the problems facing the sector, and the solutions (including improving broadband speeds and devolving skills budgets) which could help.

But the offhand reference to his own ignorance, and the implication that it would be seen as attractive by this particular audience, implies that Goldsmith, and other politicians like him, haven’t moved on since the 90s. The comment seemed designed to say: “Oh, I don't know about that - I'll leave it to the geeks like you!"

This is bad enough from a mayoral hopeful.  But on the same day, the Intelligence and Security Committee of Parliament filed its report on the Draft Investigatory Powers Bill, the legislation drafted by the Home Office which will define how and how far the government and secret services can pry into our digital communications. Throughout, there's the sense that the ISC doesn't think the department behind the bill had a firm grasp on the issues at hand. Words like "inconsistent" and "lacking in clarity" pop up again and again. In one section, the authors note:

"While the issues under consideration are undoubtedly complex, we are nevertheless concerned that thus far the Government has missed the opportunity to provide the clarity and assurance which is badly needed."

The report joins criticism from other directions, including those raised by Internet Service Providers last year, that the bill's writers didn't appear to know much about digital communications at all, much less the issues surrounding encryption of personal messages.

One good example: the bill calls for the collection of "internet connection records", the digital equivalent of phone call records, which show the domains visited by internet users but not their content. But it turns out these records don't exist in this form: the bill actually invented both the phrase and the concept. As one provider commented at the time, anyone in favour of their collection "do not understand how the Internet works". 

Politicians have a long and colourful history of taking on topics - even ministerial posts - in fields they know little to nothing about. This, in itself, is a problem. But politicians themselves are often the people extolling importance of technology, especially to the British economy - which makes their own lack of knowledge particularly grating. No politician would feel comfortable admitting a lack of knowledge, on, say, economics. I can’t imagine Goldsmith guffawing "Oh, the deficit?  That's all Greek to me!"  over dinner with Cameron. 

The mayoral candidates on stage at the DebateTech hustings this week were eager to agree that tech is London’s fastest growing industry, but could do little more than bleat the words “tech hub” with fear in their eyes that someone might ask them what exactly that meant. (A notable exception was Green candidate Sian Berry, who has actually worked for a tech start-up.) It was telling that all were particularly keen on improving internet speeds -  probably because this is something they do have day-to-day engagement with. Just don't ask them how to go about doing it.

The existence of organisations like Tech London Advocates, the industry group which co-organised the hustings, is important, and can go some way towards educating the future mayor on the issues the industry faces. But the technology and information sectors have been responsible for 30 per cent of job growth in the capital since 2009 - we can't afford to have a mayor who blanches at the mention of code. 

If we’re to believe the politicians themselves, with all their talk of coding camps and skills incubators and teaching the elderly to email, we need a political sphere where boasting that you're not "techy" isn’t cool or funny - it’s just kind of embarrassing. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.