For the past month, the scientific community has been feverishly discussing—and testing—a material called LK-99. It claims to be a superconductor at room temperature. Sounds dreadfully nerdy, but if true this would be revolutionary technology. Is this real or just hype?
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First off: Wtf is a superconductor?
You can divide all materials based on whether they can conduct electricity or not. A simple example:
Metals, such as copper and silver, allow electrons to move freely and carry with them electrical charge. Insulators, such as rubber or wood, hold on to their electrons tightly and will not allow an electrical current to flow.
The temperature effect: Since the early 20th century, physicists noticed that some materials can conduct electricity without resistance at very cold temperatures. And since then, they have discovered thousands of such materials—which they labelled as ‘superconductors’.
How they work: When electrons move through a material they collide into fixed atoms within the material—which slows down their progress. This is called resistance. But change the temperature—and these electrons whiz right through. Phys.org offers an excellent analogy we can all relate to:
On a microscopic level the electrons in a superconductor behave very differently from those in a normal metal. Superconducting electrons pair together, allowing them to travel with ease from one end of a material to another. The effect is a bit like a priority commuter lane on a busy motorway. Solo electrons get stuck in traffic, bumping into other electrons and obstacles as they make their journey. Paired electrons on the other hand are given a priority pass to travel in the fast lane through a material, able to avoid congestion.
Why they matter: Superconductors are used in countless ways—from everyday MRI machines to fancy particle accelerators—used at CERN to detect the Higgs-Boson particle (no, we are not even going to try and explain that). And they are also deployed in superfast maglev trains—the fancy kind that seem to levitate above the rails. This is because superconductors interact with magnets in an interesting way:
The magnetic field causes electrical currents to spontaneously flow on the surface of a superconductor, which then give rise to their own, counteracting, magnetic field. The effect is that the superconductor dramatically levitates above the magnet, suspended in the air by an invisible magnetic force.
The main superconductor challenge: The greatest obstacle preventing widespread use of superconductors is that they must be maintained in extremely cold temperatures:
In the simple elements for instance superconductivity dies out at just 10 Kelvin, or -263°C. In more complicated compounds, such as yttrium barium copper oxide (YBa2Cu3O7), superconductivity may persist to higher temperatures, up to 100 Kelvin (-173°C). While this is an improvement on the simple elements, it is still much colder than the coldest winter night in Antarctica.
A superconductor dream: Now you can see why a room temperature superconductor would be truly revolutionary. Imagine a world where electricity flows from a power plant to your home with zero resistance or loss. In fact, any technology that relies on conducting electricity would become superfast:
That could mean, among other things, faster microchips, cheaper medical scanners, better electric motors, the ability to transmit electricity over long distances with no losses and more. If it uses electricity or magnetism, superconductivity can improve it.
A history of false alarms: Scientists have dreamed for decades for a superconductor that operates at room temperature. And many have claimed to have struck gold—only to have their research disproved and retracted. The most famous to falsify his data was Jan Hendrik Schön—who was stripped of his doctoral degree in 2004. Two scientists from the Indian Institute of Science, suggest a concoction of gold and silver nanoparticles was a superconductor—but again, their data was bad. The latest scandal involved a prominent US academic Ranga P. Dias. In fact, this phenomenon now has its own nickname—they are dubbed a USO or unidentified superconducting object.
PS: Materials can also become superconductors when subjected to great amounts of pressure—but we’re not getting into that.
So is this LK-99 a USO too?
The Korean researchers claim to have discovered a material that is a superconductor at room temperature—and, indeed, up to around 127°C. Even better, the material is made by combining copper, lead, phosphorus and sulphur, all of which are relatively abundant and cheap.
They also shared their papers—which have not been published or reviewed as yet. The buzz was instantaneous and spread worldwide:
Prediction markets took bets on whether LK-99 is legit. arXiv, the database of scientific papers, filled up with preprints about superconductivity. There were memes, naturally. Stocks in Chinese and Korean tech companies surged. Everyone seemed absolutely primed and ready for a silver bullet that will solve the world’s problems.
It was hardly surprising since any such breakthrough would be a huge boon for a tech industry desperate for the next big thing, as one academic notes: “A technologically viable room-temperature superconductor isn’t just Nobel Prize territory. If you’ve patented it, it’s incalculable value essentially.”
Checking the claims: Soon after the announcement, many raised doubts about the research contained in the two papers. One of the co-authors even said that the paper was released without his permission. Since then, scientists around the world have been trying to replicate the results of the papers—and the results are disappointing.
A verification by a committee made up of Korean experts arrived at an initial conclusion that LK-99 is not a room-temperature superconductor. But they plan to conduct further tests. A preliminary study by Indian scientists replicated the experiments and did not find any sign of superconductivity. Researchers from China, UK and Princeton have reported the same.
A super magnet? A group of scientists at Peking University offered an interesting hypothesis:
[T]he new material is an unusual magnet. That helps explain the magnetic levitation of LK-99, which might appear similar to, but is not the same as, the total expulsion of magnetic fields found in superconducting materials.
But, but, but: It is far too early to dismiss LK-99. The papers still have to be rigorously peer-reviewed to arrive at any conclusion. These are all hasty tests performed with materials that may or may not replicate LK-99 accurately. They haven’t been reviewed either:)
The bottomline: There is nothing in the laws of physics that prevents room temperature superconductors from existing. But the frenzied desperation that accompanies any announcement of a ‘miracle’ technology ought to give us pause, as Japan Times points out:
This heated discussion—and the market response—says as much about modern times as it does science itself. The world wide web allows us to publish anything, everywhere all at once. And social media means these developments become talking points and memes even among the those who barely understand the concepts… The rush to publish, discuss, criticize and tear apart new discoveries works in conflict with the slow and deliberate nature of scientific research.
The best overviews are in CBC News, Economist and Quartz—which also raises questions about our need for miracles. The Hindu has a useful set of charts that lay out the history of superconductors. The Verge spoke to a bunch of sceptical experts. Quartz also summarises the latest attempts to replicate the results. Japan Times has an excellent op-ed raising questions about the frenzy surrounding the announcement.