Super superconductors? Don’t believe the hype

Ambient superconductivity for the masses would be a multi-trillion dollar breakthrough but it is still some way off.

The Large Hadron Collider at Cern.
The Large Hadron Collider at Cern. Credit: James King-Holmes / Alamy Stock Photo

Physics has provided copious evidence that God has a sense of humour. Want to see the entire cosmos? Sorry, says God, most of it is dark. Want to generate cold fusion power? Impossible. Travel at the speed light? Ha ha! Make room temperature superconductors? Hmmm.

The last is the most tantalising, not least because scientists keep saying they’ve done it. A few days ago a Korean team announced on arXiv, a Cornell University open access site, that they’d finally cracked it. A degree of delirium ensued.

‘Today might have seen the biggest physics discovery of my lifetime,’ cried one excited Twitterer, ‘I don’t think people fully grasp the implications of an ambient temperature / pressure superconductor.’

‘We believe,’ said the Korean scientists, ‘that our new development will be a brand-new historical event that opens a new era for humankind.’

But most responses were muted if not derisive. Superconductor watchers had been here before.

‘The paper,’ sighed an unimpressed Matt Ridley, ‘comes from an unknown team at a start-up institute with little track record in the field, it has not been peer reviewed and its charts are frankly a mess. So the betting is it will prove to be just a familiar hype-and-disappoint cycle of the kind that plagues the field of energy physics.’

Professor Jorge Hirsch at the University of California at San Diego emitted an even deeper sigh, ‘It’s not superconductivity. It’s experimental artifacts, wishful thinking and poor judgment (in the best scenario).’

The further problem was that a team at the University of Rochester in New York had announced a similar breakthrough in 2020 and, again, this year. The idea looks beautiful and exotic. It involved crushing a speck of carbon, sulphur and hydrogen (CSH) between the tips of two diamonds. The speck, it was said, superconducted at the temperature of a domestic fridge – current superconductors have to be cooled to near absolute zero.

But this first paper was withdrawn, causing doubt about the team’s methods and the second was, as a result, treated with scepticism. The second paper was also aesthetically spectacular. But the sceptical mood has now spilled over to engulf the Korean paper.

The competitive enthusiasm to make these claims is understandable. Ambient temperature and pressure superconductivity would be a multi-trillion dollar breakthrough. But, first, what is it?

Electrical currents encounter resistance because the electrons in a metal bounce around at normal temperatures and pressures. Putting extreme pressure on certain metals – imagine the pressure at the bottom of the deepest ocean trench – can make the material superconductive as can very low temperature, something close to absolute zero, minus 273 degrees C. This causes the electrons to cling together in ‘Cooper pairs’ and thereby stop them bouncing and allow electricity to flow unhindered.

You can have superconductivity at high temperatures. Scientists found that carbonaceous sulphur hydride superconducted at 15 degrees C. Unfortunately it only achieved this by being subjected to 267 gigapascals of pressure – roughly equivalent to the pressure at the centre of Jupiter.

But superconductivity is not quite as impossible as it sounds. In fact, it’s up and running. MRI machines have superconductors, as does the Shanghai Transrapid train which cruises at 268 mph. The latter uses superconducting magnets to raise it from the rails. The Large Hadron Collider at CERN also uses superconducting magnets to keep its colliding particles on track.

The most important value superconductivity has for such machinery is that, because there is no resistance, no heat is generated. Running conventionally powered magnets in an MRI machine would melt the machine and vaporise the patient.

Less friendly machines are also powered by superconductivity. Magnetically-powered railguns fire projectiles at astounding speeds – more than 6,000 mph. The scale and size of the projectile mean no explosive is necessary. Coilguns do something similar. It is a sobering thought that so many scientific breakthroughs have a military application.

But, these are still far from absolute zero or low pressure systems, they still need costly and often massive refrigeration systems. The promise of room temperature and low pressure superconductivity is that we could all have its benefits all the time.

One benefit would be that the cost of electricity would be massively reduced. This is, in part, because superconducting transition lines would reduce to nothing the roughly 10 per cent loss of power in conventional lines. But here a calculation needs to be made that links the money saved to the cost of installing entirely new cable systems.

Elecricity generation could be made cheaper and elecricity could be stored more efficiently – superconduction systems need never suffer any loss of power which suggests the possibility of forever batteries. It would be a relief to see the back of the Duracell and Energizer Bunnies.

Potentially the most world-changing effects would be in computing. For a start current AI can conduct massive searches to find potential superconductive materials. It has already been hugely successful in protein folding – how proteins manage to fold themselves into biologically functional structures. Similarly, it could search every material in the world in search of superconductivity.

But superconductivity is already transforming quantum computing. Ordinary computers use bits as their basic unit, quantum computers use qubits. The former are either on or off – 1 or 0 – while the latter can be both on and off. This means they can calculate much faster using multiple pathways and come up with multiple answers – which sounds awful but is, apparently, a good thing. Quantum computing has not yet replaced ordinary computing, but ambient superconductivity could get us there.

The explosive development of science in the last 150 years has persuaded us to celebrate every possibility, no matter how astounding, as a probability. No wonder, the impossible has often turned out to be real – curved space and time, nuclear power, flight to the moon, the wild weird world of quantum theory and so on.

In reality the speed of innovation is almost certainly slowing as the number of real breakthroughs is limited by the rate of past discoveries. Lord Rees, Astronomer Royal and our most sober futurologist, puts the hope of ambient superconductivity in the near future in perspective: ‘If I were asked to bet I would put at least a 10 per cent probability of success in 10 years – much higher, incidentally, than I would for cold fusion.’


Bryan Appleyard