By Liam Mannix
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When news about a new room-temperature superconductor crossed my desk, I was sceptical. “Last group to claim this just had to retract their paper for being wrong,” I wrote to my editor.
Scepticism is the default position for scientists and science journalists. But speaking to superconduction researchers today, I found them surprisingly open to the possibility of a breakthrough.
An artist’s conception of magnetic levitation above a superconductor. Credit: iStock
The search for a superconductor that can transmit electricity at room temperature much more efficiently than traditional conductors such as copper wire has been a goal of the physics community for decades. While superconductors do exist, powering MRI machines for example, currently they can only operate at extremely low temperatures. The prospect of a superconductor that can transmit electricity at room temperature with no loss of power in transmission opens up tantalising possibilities such as developing super-powered motors, which would speed up the electrification of transport.
However, superconducting physics are so complex, we can’t accurately predict the properties of a superconductor. “If it happened, it could happen by accident,” said Professor Michael Fuhrer, director of the ARC Centre of Excellence in Future Low-Energy Electronics Technologies at Monash University.
“It’s not ridiculous to think this could just come out of left field.”
Another Australian team is already trying to make the material themselves.
“A new era for humankind”
Our story starts with two preprints. One, a six-author preprint, was uploaded to arXiv – a server where scientists post papers before they have been peer-reviewed and published – on July 22.
The second study that has not yet been peer-reviewed – actually uploaded first, by a few hours – had two different features: a sexier title and just three authors. Three is the magic number in science, as that’s how many people can share a Nobel Prize.
The reported discovery of a compound known as LK-99, which works as a room-temperature superconductor, set off an internet frenzy. Some hailed it as a once-in-a-lifetime scientific breakthrough.
But that second paper is … unusual. After describing LK-99, the researchers finish with a phrase I don’t think I’ve seen before in a scientific paper.
“We believe that our new development will be a brand-new historical event that opens a new era for humankind.”
ArXiv publishes a lot of non-peer-reviewed papers every day – the flotsam of the scientific process.
“These ‘Unidentified Superconducting Objects’, as they’re sometimes called, reliably show up on the arXiv. There’s a new one every year or so,” Inna Vishik, a condensed-matter experimentalist at the University of California, Davis, told Nature.
But LK-99 caught the eye of users of X, formerly known as Twitter, including one frozen coffee entrepreneur, who posted: “Today might have seen the biggest physics discovery of my lifetime.”
That picked up 28,000 retweets and helped cue an explosion of hype.
What is a superconductor?
Your house receives electricity through a thick wire. Down the wire run electrons – negatively charged particles. The particles pour into your toaster and burn your toast.
As the electrons run down the wire, they bump on atoms in the cable, causing friction. Our electricity grid loses about 10 per cent of its power to friction. Old electric lightbulbs used this property to convert electricity into heat and light.
Superconductors transmit electricity with no friction and no loss. How?
Electrons normally repel each other, as they are negatively charged. Superconductors coax this force to break down. Electrons pair up and so are much harder to bump, reducing friction to zero.
Superconductors also expel magnetic fields, allowing them to levitate above magnets.
But superconductors remain of limited use, in part because of the extreme conditions required – extremely high pressures or temperatures lower than minus 100 degrees. Since they were discovered, scientists have slowly discovered superconductors that work closer to room temperature – but progress has stalled since the 1990s, Fuhrer said.
What could we do with one?
We already have superconductors. They power MRI machines, fusion reactors and an under-construction magnetic-levitation train line in Japan.
A room-temperature superconductor would obviously be far more practical; Japan has to cool its maglev superconductors to minus 269 degrees. We could rewire the electricity grid.
“Just by doing that, we would get a very significant direction to achieving our goals for mitigating CO₂,” said Dr Richard Taylor, a superconductor researcher at the Queensland University of Technology.
We could even build superfast electronics and push forward practical quantum computers, or build more powerful electric motors – useful as we try to electrify transport.
Does LK-99 stack up?
LK-99 can be made by baking lanarkite and copper phosphide. The paper claims it is super-conducting and displays magnetic levitation at room temperature.
Is that likely to be true?
Superconducting science is no stranger to controversy. Just last year a paper claiming to have found a room-temperature superconductor was retracted by Nature, the world’s top scientific journal.
That’s important, I think. If we can’t trust a paper that made it into Nature, how much weight can we give a preprint?
Reporting from South Korea raises more questions, with one author apparently upset the paper was published before peer review.
Other teams are working to replicate the discovery, including Taylor, who said he was working on getting the materials. “It seems to be quite hard to synthesise.”
As of last Friday, several practical experiments and computer simulations had been unable to, Nature reported – even the ones that X got excited about. Another team posted a paper to arXiv claiming the material wasn’t superconducting at all, merely a magnet.
What about the original LK-99 papers? Researchers described them as “sloppy” and “fishy” to Science, but that may simply be a presentation issue – this is a study that has not yet been peer-reviewed.
Where does this leave us? “We have to wait and see what other groups can do to reproduce the results,” Taylor said. “That’s how the scientific method works.”
Liam Mannix’s Examine newsletter explains and analyses science with a rigorous focus on the evidence. Sign up to get it each week.
correction
This article originally suggested the six-author LK-99 study was uploaded before the three-author study. This is incorrect, and has now been fixed.