Vanishing act: the Italian physicist Ettore Majorana, who disappeared in 1938. Photo: Kanijoman/Flickr
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The vanishing particle physicist and the puzzle he left behind

Ettore Majorana was an Italian physicist, the best of his generation, who disappeared in mysterious circumstances in 1938.

You probably haven’t heard of Majorana fermions. You probably haven’t heard of fermions, for that matter – nor of Ettore Majorana. Prepare yourself: it’s a story of mystery and frustration.

Let’s deal with the man first. Majorana was an Italian physicist, the best of his generation, who disappeared in mysterious circumstances in 1938. He emptied his bank account, bought a ticket for a boat ride from Palermo to Naples and left a note for his colleagues apologising for the inconvenience he was about to cause. He may have committed suicide but his body was never found. There are rumours of subsequent sightings in Buenos Aires. Some think that he abandoned physics and disappeared to live out his days in a secluded monastery.

Majorana’s specialism was quantum theory and it is tempting to think that he engineered his disappearance to reflect the subject’s strange ambiguities. A quantum particle such as an electron can be in two places at once, or simultaneously moving in two different directions; Majorana seemed to want his friends to wonder whether he could, too.

And so to his fermions. Just before his vanishing trick, Majorana predicted the existence of a particle with highly unusual properties. Although we have never seen one directly, there is every reason to think that it does exist and scientists on the 77-year-long hunt are tantalisingly close to pinning it down. This month, a group of Princeton University researchers added to the accumulating pile of evidence that the Majorana fermion is a real and fundamental building block of nature.

A fermion is one of the two types of particle that make up all matter. You have probably heard of the other one, the boson, because of all the Higgs fuss. Fermions are just as interesting. The building blocks of the atom – protons, neutrons and electrons – are all fermions. Majorana fermions have an added twist. Unlike protons, neutrons and electrons, they are their own antiparticle.

That is very odd. Matter and antimatter annihilate each other when they come into contact. Bang an electron and its antiparticle, the positron, together and they will disappear in a flash of energy. So how can a Majorana fermion be its own antiparticle?

To find out, we have to get one we can observe, hence the hunt. And in a peculiar case of life (or death) imitating art (or science), Majorana fermions are offering glimpses of their properties in materials crammed with ghostly particles that don’t actually exist.

When a solid conducts electricity, it does so because it contains negatively charged electrons that can move through the material. As they leave their usual position, the electrons leave behind a network of “holes”. Viewed from one perspective, these behave like real particles that have a charge opposite to the electron. The details get complicated but, in some materials, this can create a situation in which the moving charges and holes amount to something that behaves exactly like a Majorana fermion. That’s what the Princeton researchers have seen.

It has been very difficult to get this far. The material containing the Majorana fermion was just one atom wide and three atoms thick and had to be cooled to -272°C, one degree above the coldest temperature allowed by the laws of physics. The fermion was so small that it required a scanning-tunnelling microscope two storeys high to see it.

That said, although the observed particle is a good facsimile, it is frustratingly still more like a Majorana fermion’s shadow puppet than the real thing. Majorana’s legacy still eludes us. That note was not apologetic enough. 

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 22 October 2014 issue of the New Statesman, Why Britain and Germany aren't natural enemies

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“Socialism with an iPad” isn't as ludicrous as it sounds

Technology is changing the labour market faster than ever before. John McDonnell argues that it's the state's responsibility to make sure the outcome is fair for everyone. 

The speech shadow chancellor John McDonnell gave at Imperial College earlier today started fine. As my colleague George Eaton points out, McDonnell was valiantly attempting to reframe the economic debate – to show how investment, especially in technology research and infrastructure, could reinvigorate the economy in ways austerity can’t. 

But then he got to the last line. “It’s socialism,” he summed up, “but socialism with an iPad.”

The clunky slogan sailed a thousand The Thick of it references (Bat People and App Britain featured prominently), and its use as a soundbite across the media made McDonnell’s argument look out-of-touch and embarrassing. But in the context of his argument, the line isn’t as nonsensical as it sounds.

Buried in the speech were a number of important arguments about how we let technological advancement come about. It’s lazy to assume that technology is inherently democratic, and will necessarily bring about a fairer society – as things stand, it’s deepy embedded in capitalism. But it's also changing the labour market faster than ever before: automation and robotics will soon mean that most tasks can be carried out  by machine, making those who control those machines vastly more powerful than those who don’t. 

In his speech, McDonnell pointed out that automation will replace low-paid workers first:

Technological advance is forcing the pace of change. Bank of England research suggests that 15 million jobs could be at risk of automation over the next decade or so. And those most at risk from automation are the lowest-paid.

He added that technological advances, and the changes they’ll make to the labour market, must be managed by the state so that workers don't lose out. Technology contributes to the wealth gap, and could well make it worse, unless, as McDonnell says, the government “understands and accepts the strategic role it has to play in our new economy”. This sounds woolly, but it's an important point - Tory policy on issues like tax or the the Transatlantic Trade Partnership (TTIP) has been remarkably hands-off in ceding power to large corporations. 

McDonnell implied that a large and involved state is crucial in a globalised, technological world, to ensure that workers' rights don't fall through the cracks and inequalities don't widen. A large welfare state would help cushion workers in a changing economy -  tax credits, as McDonnell explained earlier, can help make up for low wages in small, start-up businesses. 

Corporations have a poor record of improving working life and helping out those unable to work, or whose skills become redundant. These safeguards will become ever-more important as technology changes the labour market forever. And it’s here, McDonnell argued, that a bit of socialism will be needed. Even if it's carrying an iPad. 

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