Space & Physics
Superconducting Saga: What happened to LK-99?
The community of condensed matter physicists was put under spotlight in the wake of a paper, triggering a frenzy like none other in recent times.
In July 2023, two South Korean experimental physicists, Lee Sukbae and Kim Ji-Hoon published a pre-print in arXiv, claiming discovery of superconductivity in a sample, occurring at room temperature.
The condensed matter physics community was put under spotlight in the wake of this paper, triggering a frenzy like none other in recent times.
The material dubbed, LK-99, after the initials of the South Korean physicists, promised nothing short of a revolution to the electronics industry.
But before I go further, let’s go through some superconductivity basics.
What are superconductors?
Basically, superconductivity is a macroscopic quantum phenomenon. Our story begins with two ground-breaking experiments.
In 1911, the Dutch physicist, Heike Onnes observed that a mercury wire dipped in liquid helium, offered zero resistance to the passage of electricity, when the temperature of the mercury was lowered to-269◦ C.
In 1937, Pyotr Kapitsa, John F. Allen and Don Misener discovered that at an even lower temperature close to -273◦ C, liquid helium-4 transformed into a superfluid. A superfluid’s an exotic fluid exhibiting zero viscosity.
Both these exotic phenomena of superfluidity and superconductivity are closely linked, though they’re not the same.
However, this effect would go for years without a solid theory, until the physicists’ trio, John Bardeen, Leon Cooper and John Schrieffer, put together a ‘complete’ microscopic theory, known as the ‘BCS theory’. The theory makes a number of quantitative predictions about the behavior of superconductors. Most importantly, it shows how pairs of electrons would couple to form Cooper pairs, overcoming mutual repulsion below a set critical temperature. Bardeen, Cooper and Schrieffer would go on to win the 1972’s Nobel Prize in Physics for this work.
As much as superconductors revolutionized the electronics industry in the 20th century, the temperatures at which this effect is commonly seen is in the same regime as outer space. It takes resources for laboratories to reach these temperatures. But imagine if nature showed us a material that can become a superconductor at room temperature …
The case for ‘room temperature’ superconductors
But you may be wondering what’s the big deal with room temperature superconductors anyway? For one, they’re promising an overnight revolution of sorts in the electronics industry. The approximately 7% loss of energy there is to pass currents through wires during transportation, can be brought down to near zero with room temperature superconductors. Another important use of these superconductors would be in the development of strong magnetic fields. Strong stable magnetic fields are used in MRI imaging and maglev trains.
Source: Ramon Salinero / Unsplash
This could make such technologies more accessible and cheaper to the public. Renewable energy generation from solar and wind power could see their efficiency rise with the help of room-temperature superconductors. The use of room-temperature superconductors could grow exponentially more after its discovery, even in applications we do not know yet. Think of the world today without any semiconductors, it would be tough to live without our LED lamps or solar panels. Similarly, room temperature superconductors could inexorably revolutionize our way of living for the better. I mean, who knows? Nobody knows! It’s yet to be invented.
Sukbae and Kim claimed that LK-99 displayed superconductivity when the temperature dropped below 127◦ C. They claimed to have observed zero resistance currents.
And that was all it took for social media savvy tech entrepreneurs to embark on a hype train, and spread the word on room temperature superconductors potentially being real at last. Except it’s not technically room temperature – for 127◦ C is way past the boiling point of water. But it’s much easier for laboratories to set up an experiment, investigate and replicate 127◦ C.
The dream fever isn’t abating away, but the proof really is in the pudding.
There’s nothing to say room temperature superconductors can’t exist. In fact, scientists who worked in producing these results have also shared this opinion in their work.
Conventional superconductivity – with extreme cold critical temperatures – was challenged back in 1986, when certain cuprate compounds such as yttirium barium copper oxide (or YBCO) were discovered. They have a higher critical temperature of -183◦ C, which is still very cold, but still warmer compared to helium-4. Such critical temperatures are outside the realm of the standard BCS theory, with the main mechanisms underpinning them being a topic of research.
The race for verification
After their paper was submitted in arXiv, Sukbae and Kim released a video of the levitating LK-99 sample on a magnet – a hallmark signature of the Meissner effect. The Meissner effect is a prediction of the standard BCS theory – when magnetic field lines are ousted from within the material itself.
They provided a detailed description of how LK-99 can be synthesised. This led materials labs from across the world to descend into a frenzy to try and replicate their results.
Some of the earliest research were done at the National Physics Laboratory (NPL) in New Delhi and Beihang University in Beijing (BU).
A team from the Southeast University in Nanjing, observed a near-zero resistance in LK-99 at -163 ◦ C. The team from Nanjing used an X-ray diffraction technique consistent with the work that the Korean scientists had published.
And then the theorists entered the fray. Sinead Griffin from the Lawrence Berkeley National Laboratory, US, performed calculations to suggest there really were telltale signs of room temperature super conductance in LK-99. Specifically, possible mechanisms for forming Cooper pairs were identified.
While these results were tantalising, they did not give conclusive evidence of superconductivity.
The Meissner effect – or what the South Koreans claimed was the Meissner effect- couldn’t be replicated in any other studies.
Griffin attained social media popularity after her tweets with over 14K followers on X. However, truth be told – Griffith wasn’t explicitly backing anybody – but was merely giving the South Koreans’ work a fair shot.
The last twist in the saga came when she said, “My paper did *not* prove nor give evidence of superconductivity”.
Realization dawns
And suddenly, it wasn’t going in LK-99’s favour at all. It turned out the research team at Southeast University in Nanjing, had made incorrect measurements using faulty instrumentation, meaning they were unreliable.
Whereas, the studies from India’s National Physical Laboratory (NPL) and Beihang University didn’t find report any superconductivity effect. In fact, it just seemed like dull, grey metal.
But the final series of nails in the coffin were the conclusive results by Yuan Li at Peking Institute, and Yi Jiang at the Donostia International Physics Centre, Spain. They proved beyond doubt that LK-99, as synthesised by the South Korean team, was a ferromagnet. Yuan Li also explained the levitating video of LK-99 pellets over a magnet was a result of ferromagnetism. He also showed the absence of superconducting current at low temperatures.
A ferrofluid exhibiting ferromagnetic properties; Source: Etienne Desclides / Unsplash
Science is often rife with controversies and debatable results. Many physicists have published unconfirmed, and published plagiarized work. Some notable examples include the alleged groundbreaking work of Jan Schön, who claimed discovery of organic transistors. Only to be charged with fraud after he made up his results, thus bringing him disrepute that brought an end to his scientific career pretty early on.
Then there was the work by Anshu Pandey and Dev Thapa on similar claims of room temperature superconductors that weren’t replicated.
Although it’s unfortunate that this saga ended so disappointingly with LK-99, I am not, in any manner suggestive of the fact that room-temperature superconductivity cannot exist.
Scientists who worked in producing these results have also shared this opinion in their work. Many scientists have however also shared the need to understand the results and related nitty gritty, before jumping the gun.
However, the collaboration amongst scientists at universities across the world, was focused on uncovering LK-99’s true properties.
It wasn’t just mere claims, backed by data, but also the peer-review process that helped redefine public discourse, and set the facts straight. And that had made all the difference.
Space & Physics
Indian-Belgian Team Develops Portable Detectors to Image Mountains and Monuments Using Cosmic Rays
Portable cosmic-ray detectors could help researchers examine mountains, tunnels and historical monuments without invasive procedures, opening new possibilities for scientific imaging and infrastructure inspection.
An international team of researchers from India and Belgium has developed portable particle detectors that could help scientists examine the interiors of mountains, tunnels and historical monuments without damaging them. The technology uses naturally occurring cosmic-ray particles to map variations in the density of objects, offering a potential approach to non-invasive imaging of large structures.
The detectors, developed using glass-based Resistive Plate Chambers (RPCs), achieved a particle-detection efficiency exceeding 95% during testing, according to a report published by Research Matters on October 24, 2026. The findings demonstrate the potential of compact detector systems to investigate dense materials and support future applications in geology, archaeology and infrastructure assessment.
The collaboration includes researchers from India’s National Institute of Science Education and Research (NISER), Bhubaneswar, and the Homi Bhabha National Institute (HBNI), alongside researchers from Belgian institutions, including Université catholique de Louvain and the Inter-University Institute for High Energies.
How cosmic rays reveal hidden structures
The technology uses muons, high-energy particles produced when cosmic rays interact with Earth’s atmosphere. These particles continuously reach the Earth’s surface and can penetrate substantial thicknesses of rock, concrete and other materials.
As muons travel through an object, some are absorbed or deflected depending on its density and thickness. By measuring the number and trajectories of particles passing through a structure, researchers can identify variations in internal density and reconstruct images of otherwise inaccessible areas.
The technique, known as muography, is comparable in principle to X-ray imaging, but uses naturally occurring particles instead of an artificial radiation source. It has previously been used to investigate geological formations, including volcanoes, and to explore archaeological structures.
However, conventional muon detectors can be bulky, difficult to transport and challenging to operate in remote locations. The new glass-based detectors aim to address some of these limitations through a compact design and sealed operation, reducing dependence on continuous gas supplies.
Testing the detector system
The researchers developed three glass RPC prototypes using thin glass electrodes separated by gas-filled gaps. When a muon passes through a chamber, it ionises the gas, generating an electrical signal that can be recorded to determine the particle’s position.
Electronic readout systems capture these signals and help reconstruct the trajectories of incoming particles. During testing, the detectors achieved an efficiency exceeding 95%, with a timing resolution of approximately 1.8 nanoseconds, according to the research report.
To examine the system’s ability to detect dense materials, the team conducted an absorption experiment using one prototype. During an open-sky measurement, researchers recorded nearly 55,000 muon tracks. After placing a lead block in the experimental setup, the recorded count fell to 30,894, demonstrating how dense material reduced the number of particles reaching the detector.
Representational image.Image credit:Pexels
The experiment provided proof of principle that the system could measure muon attenuation and support radiographic imaging. However, imaging complex structures such as mountains or monuments requires measurements from multiple directions and further computational reconstruction.
Applications and challenges ahead
Portable muon detectors could eventually help researchers investigate hidden cavities, examine geological formations, inspect tunnels and study the internal structures of historical monuments. Engineers could also explore their application in assessing infrastructure such as dams and bridges, although these uses would require additional testing and validation.
For cultural heritage conservation, muography could offer a valuable alternative where drilling or other invasive investigations risk damaging fragile structures. A 2025 review published in iScience highlighted the technique’s potential as a complementary, non-destructive method for studying cultural heritage objects, while noting that the relatively low flux of naturally occurring muons can require lengthy data-collection periods.
The technology is not yet a universal replacement for existing inspection methods. Its practical application will depend on factors such as spatial resolution, detector size, measurement duration and the complexity of the structure being examined.
The researchers have proposed further improvements, including lighter structural materials, larger detector areas and enhanced readout systems. These developments could make the detectors easier to deploy and improve the quality of reconstructed images.
Space & Physics
How Scientists Traced the Flow of Matter Around a Dead Star Using X-rays
By studying changes in X-ray signals from Centaurus X-3, researchers at Bengaluru’s Raman Research Institute have found evidence of an unusual way in which matter reaches a neutron star. The discovery could change how scientists explain the radiation coming from this distant system.
When a massive star dies, its core can collapse into an extremely dense object called a neutron star. Despite being only about the size of a city, it can have a mass comparable to that of the Sun. Its powerful gravity can pull matter away from a nearby companion star, releasing energy in the form of X-rays as the material falls towards it.
Scientists at Bengaluru’s Raman Research Institute (RRI) have studied these X-ray signals from Centaurus X-3, a star system about 24,000 light-years from Earth. By examining changes in the signals, the researchers identified a stream of matter flowing towards the neutron star and found evidence of a rotating disk of material around it. This is an unusual finding because such disks are not commonly expected in this type of star system. The discovery could help scientists better understand how matter moves around neutron stars and how these distant objects produce X-rays.
Star That Pulls in Matter
Centaurus X-3 is in the constellation Centaurus. It belongs to a class of systems known as high-mass X-ray binaries. These systems contain a neutron star and a massive companion star held together by gravity.
A neutron star forms when the core of a massive star collapses at the end of its life. It packs roughly the Sun’s mass into a sphere only about the size of a city. Its gravity is so strong that it can pull in material from a nearby companion star. As this material falls towards the neutron star, it releases enormous amounts of energy, including X-rays. Scientists study this radiation to understand how the material behaves and how the system works.
Centaurus X-3 is also a pulsar. Its neutron star rotates and sends out radiation from regions near its magnetic poles. As the star spins, these beams sweep across space. When a beam passes an observing satellite, the satellite detects a pulse of radiation, much as a lighthouse produces a repeating flash as it turns. These regular pulses provide scientists with a way to study the neutron star and its surroundings.
What the Changing Signals Revealed
The radiation from Centaurus X-3 does not come only from the neutron star itself. Some of it interacts with nearby material, including the surface of the companion star, gas flowing away from it and matter surrounding the neutron star. This material absorbs radiation and emits it again. Scientists call this secondary radiation.
Changes in this radiation can help researchers work out what is happening around the neutron star. However, Centaurus X-3 is so far away that telescopes cannot clearly distinguish its surrounding structures. It appears as a single point of light. Scientists must therefore piece together the system’s structure from the signals they receive.
Earlier observations had shown that the intensity of certain secondary X-ray emission lines changed as the neutron star rotated. An emission line is a feature in a spectrum that can reveal information about the material producing or interacting with the radiation. A research team led by Kinjal Roy of RRI examined four such emission lines in detail. The researchers found that the structure producing these changes must be rotating along with the neutron star.
The pattern helped them identify the likely source which is a stream of matter moving towards the neutron star.
Following the stream of matter
This stream is part of a process called accretion, in which a compact object draws in material from its surroundings. In Centaurus X-3, the stream carries matter from an accretion disk towards the neutron star. The disk is a rotating structure of gas and other material that moves around the star before being drawn inwards. The neutron star’s magnetic field then guides the incoming matter towards its magnetic poles.
The stream also changes what an observing satellite sees. As it moves around the neutron star, it can come between the satellite and the star, partially blocking the direct radiation. When this happens, the primary X-ray signal weakens. At the same time, radiation from the stream itself becomes stronger in the observed signal.
The researchers used these changing signals to connect the observed variations to the movement of matter around the neutron star. The evidence for an accretion stream also points to an accretion disk feeding it. This matters because scientists generally expect high-mass X-ray binaries to gather material in a different way.
Why an accretion disk matters
In many high-mass X-ray binaries, a neutron star captures gas directly from the stream of material blown away by its companion star. This is known as stellar-wind accretion. An accretion disk involves a different arrangement: material gathers into a rotating structure before flowing towards the neutron star. The findings from Centaurus X-3 indicate that this disk-based process is taking place in a system where it is not generally expected.
That difference matters when scientists calculate how the system produces and releases radiation. If their models leave out the disk, they may fail to account for some of the radiation coming from the surrounding material.
“Accretion disk is not expected to occur in [HMXBs] So, if an accretion disk is forming in this system, emission models have to be modified,” Roy said in the Department of Science and Technology’s announcement. He added that future models of Centaurus X-3 would need to account for radiation from the disk.
The research does not mean that scientists have directly photographed the disk. Instead, they have used the changing X-ray signals to infer the presence and behaviour of structures that remain too distant to resolve clearly. Published in The Astrophysical Journal, the study adds to the understanding of Centaurus X-3, one of the most widely studied binary pulsars. It also shows how small changes in radiation can reveal the movement of matter around objects that are otherwise beyond the reach of direct observation.
By identifying the flow responsible for the changing signals, the researchers have provided a more detailed picture of how this neutron star draws in material. That picture will help scientists refine their models of Centaurus X-3 and examine whether similar processes occur in other high-mass X-ray binaries.
Space & Physics
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