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

Show Hide image’s censorship story is a striking insight into Google’s unchecked power

The founder of the community-driven website claims its advertising revenue was cut off for five weeks.

When Microsoft launched its new search engine Bing in 2009, it wasted no time in trying to get the word out. By striking a deal with the producers of the American teen drama Gossip Girl, it made a range of beautiful characters utter the words “Bing it!” in a way that fell clumsily on the audience’s ears. By the early Noughties, “search it” had already been universally replaced by the words “Google it”, a phrase that had become so ubiquitous that anything else sounded odd.

A screenshot from Gossip Girl, via

Like Hoover and Tupperware before it, Google’s brand name has now become a generic term.

Yet only recently have concerns about Google’s pervasiveness received mainstream attention. Last month, The Observer ran a story about Google’s auto-fill pulling up the suggested question of “Are Jews evil?” and giving hate speech prominence in the first page of search results. Within a day, Google had altered the autocomplete results.

Though the company’s response may seem promising, it is important to remember that Google isn’t just a search engine (Google’s parent company, Alphabet, has too many subdivisions to mention). Google AdSense is an online advertising service that allows many websites to profit from hosting advertisements on its pages, including the New Statesman itself. Yesterday, Drew Curtis, the founder of the internet news aggregator, shared a story about his experiences with the service.

Under the headline “Google farked us over”, Curtis wrote:

“This past October we suffered a huge financial hit because Google mistakenly identified an image that was posted in our comments section over half a decade ago as an underage adult image – which is a felony by the way. Our ads were turned off for almost five weeks – completely and totally their mistake – and they refuse to make it right.”

The image was of a fully-clothed actress who was an adult at the time, yet Curtis claims Google flagged it because of “a small pedo bear logo” – a meme used to mock paedophiles online. More troubling than Google’s decision, however, is the difficulty that Curtis had contacting the company and resolving the issue, a process which he claims took five weeks. He wrote:

“During this five week period where our ads were shut off, every single interaction with Google Policy took between one to five days. One example: Google Policy told us they shut our ads off due to an image. Without telling us where it was. When I immediately responded and asked them where it was, the response took three more days.”

Curtis claims that other sites have had these issues but are too afraid of Google to speak out publicly. A Google spokesperson says: "We constantly review publishers for compliance with our AdSense policies and take action in the event of violations. If publishers want to appeal or learn more about actions taken with respect to their account, they can find information at the help centre here.” has lost revenue because of Google’s decision, according to Curtis, who sent out a plea for new subscribers to help it “get back on track”. It is easy to see how a smaller website could have been ruined in a similar scenario.

The offending image, via Fark

Google’s decision was not sinister, and it is obviously important that it tackles things that violate its policies. The lack of transparency around such decisions, and the difficulty getting in touch with Google, are troubling, however, as much of the media relies on the AdSense service to exist.

Even if Google doesn’t actively abuse this power, it is disturbing that it has the means by which to strangle any online publication, and worrying that smaller organisations can have problems getting in contact with it to solve any issues. In light of the recent news about Google's search results, the picture painted becomes more even troubling.

Update, 13/01/17:

Another Google spokesperson got in touch to provide the following statement: “We have an existing set of publisher policies that govern where Google ads may be placed in order to protect users from harmful, misleading or inappropriate content.  We enforce these policies vigorously, and taking action may include suspending ads on their site. Publishers can appeal these actions.”

Amelia Tait is a technology and digital culture writer at the New Statesman.