A photograph of the Large Hadron Collider in the Science Museum. Photo: Getty
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Entangled in photons: the spooky behaviour of light particles

If you’re after science that makes you question your place in the universe, focus on that phrase “light years”, one that astronomers use so casually.

We are constantly making discoveries that reveal new wonders of the universe. Research presented in June, for instance, shows that some of its most spectacular features, such as the vast towers of gas and dust known as “the Pillars of Creation”, are a result of the way massive stars emit radiation that sculpts nearby gas clouds.

Those pillars are roughly four light years high and 7,000 light years away – which is close, compared to another discovery made recently. Scientists have found three black holes orbiting each other just over four billion light years away.

It’s an extraordinary thing to see things that distant, but in many ways this is just cosmic stamp collecting. These discoveries are informative – breathtaking, even – but they don’t cause you to question your place in the universe.

If that’s what you’re after, focus on that phrase “light years”, one that astronomers use so casually. Herein lies a truly discomfiting mystery.

Light years are a measure of the distance a photon – a packet of light energy – travels in a year. It’s a useful measure because light is the fastest thing in the universe. Yet we are still getting to grips with the properties of photons and it seems that they don’t experience distance in the same way as we do.

Fifty years ago, a Cern physicist called John Bell outlined the weirdness of photons. In a 1964 paper that built on some of Einstein’s work, Bell showed that they defy all ordinary notions of time and space. The phenomenon Bell explored is popularly known as “quantum entanglement”. It involves what Einstein once termed “spooky action at a distance” occurring between two particles. The spookiness begins when we make two photons interact in a way that leaves them entangled – the information about one is partly held in the other. The particles are “complete” only as a pair. Then we keep one on earth while sending the other to, say, the Pillars of Creation. It turns out that we can instantaneously influence the distant photon’s measured properties, such as its direction of spin.

That influence occurs because the spins of an entangled pair of photons are random but linked. You can think of it rather like knocking over two coins that are spinning on their edges. If we poke the one on earth, it might come up heads (entirely at random). If it does, we find, weirdly, that an immediate knock to the other one out there at the Pillars of Creation will give us a tail.

This cosmic connection can’t involve any signals passing between them: it would have to be quicker than light. The only explanation is that photons inhabit a reality beyond the space and time in which we live out our existence.

Entanglement’s delicate nature makes it a kind of tamper-proof seal. In the emerging science of quantum cryptography, entangled photons provide security guaranteed by the laws of physics. Financial institutions already use such measures and we are about to extend the network into space. A team of Italian researchers announced last month that they had bounced photons between satellites and earth without disturbing their quantum properties, laying the groundwork for “quantum communications on a planetary scale”. Here’s the wondrous fact: we are engineering a cosmic network that we may never fully understand. 

Michael Brooks’s “At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise” is published by Profile (£12.99)

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 July 2014 issue of the New Statesman, After God Again

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Don’t shoot the messenger: are social media giants really “consciously failing” to tackle extremism?

MPs today accused social media companies of failing to combat terrorism, but just how accurate is this claim? 

Today’s home affairs committee report, which said that internet giants such as Twitter, Facebook, and YouTube are “consciously failing” to combat extremism, was criticised by terrorism experts almost immediately.

“Blaming Facebook, Google or Twitter for this phenomenon is quite simplistic, and I'd even say misleading,” Professor Peter Neumann, an expert on radicalisation from Kings College London, told the BBC.

“Social media companies are doing a lot more now than they used to - no doubt because of public pressure,” he went on. The report, however, labels the 14 million videos Google have removed in the last two years, and the 125,000 accounts Twitter has suspended in the last one, a “drop in the ocean”.

It didn’t take long for the sites involved to refute the claims, which follow a 12-month inquiry on radicalisation. A Facebook spokesperson said they deal “swiftly and robustly with reports of terrorism-related content”, whilst YouTube said they take their role in combating the spread of extremism “very seriously”. This time last week, Twitter announced that they’d suspended 235,000 accounts for promoting terrorism in the last six months, which is incidentally after the committee stopped counting in February.

When it comes to numbers, it’s difficult to determine what is and isn’t enough. There is no magical number of Terrorists On The Internet that experts can compare the number of deletions to. But it’s also important to judge the companies’ efforts within the realm of what is actually possible.

“The argument is that because Facebook and Twitter are very good at taking down copyright claims they should be better at tackling extremism,” says Jamie Bartlett, Director of the Centre for the Analysis of Social Media at Demos.

“But in those cases you are given a hashed file by the copyright holder and they say: ‘Find this file on your database and remove it please’. This is very different from extremism. You’re talking about complicated nuanced linguistic patterns each of which are usually unique, and are very hard for an algorithm to determine.”

Bartlett explains that a large team of people would have to work on building this algorithm by trawling through cases of extremist language, which, as Thangam Debonnaire learned this month, even humans can struggle to identify.  

“The problem is when you’re dealing with linguistic patterns even the best algorithms work at 70 per cent accuracy. You’d have so many false positives, and you’d end up needing to have another huge team of people that would be checking all of it. It’s such a much harder task than people think.”

Finding and deleting terrorist content is also only half of the battle. When it comes to videos and images, thousands of people could have downloaded them before they were deleted. During his research, Bartlett has also discovered that when one extremist account is deleted, another inevitably pops up in its place.

“Censorship is close to impossible,” he wrote in a Medium post in February. “I’ve been taking a look at how ISIL are using Twitter. I found one user name, @xcxcx162, who had no less than twenty-one versions of his name, all lined up and ready to use (@xcxcx1627; @xcxcx1628, @xcxcx1629, and so on).”

Beneath all this, there might be another, fundamental flaw in the report’s assumptions. Demos argue that there is no firm evidence that online material actually radicalises people, and that much of the material extremists view and share is often from mainstream news outlets.

But even if total censorship was possible, that doesn’t necessarily make it desirable. Bartlett argues that deleting extreme content would diminish our critical faculties, and that exposing people to it allows them to see for themselves that terrorists are “narcissistic, murderous, thuggish, irreligious brutes.” Complete censorship would also ruin social media for innocent people.

“All the big social media platforms operate on a very important principal, which is that they are not responsible for the content that is placed on their platforms,” he says. “It rests with the user because if they were legally responsible for everything that’s on their platform – and this is a legal ruling in the US – they would have to check every single thing before it was posted. Given that Facebook deals with billions of posts a day that would be the end of the entire social media infrastructure.

“That’s the kind of trade off we’d be talking about here. The benefits of those platforms are considerable and you’d be punishing a lot of innocent people.”

No one is denying that social media companies should do as much as they can to tackle terrorism. Bartlett thinks that platforms can do more to remove information under warrant or hand over data when the police require it, and making online policing 24/7 is an important development “because terrorists do not work 9 to 5”. At the end of the day, however, it’s important for the government to accept technological limitations.

“Censorship of the internet is only going to get harder and harder,” he says. “Our best hope is that people are critical and discerning and that is where I would like the effort to be.” 

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