In James Cameron’s 2009 sci-fi blockbuster Avatar, Unobtanium, a brilliant silver and blue glass-like mineral is at the heart of the plot. It’s found on the moon Pandora, inhabited by the Na’avi—a race of nature-worshipping cyan-coloured humanoids. The presence of the mineral creates conflict between them and the humans
But why were the humans after it?
The answer can be found in one of physics’ real-life obsessions over the past century.
According to the Avatar Fandom Wiki, unobtanium is a room-temperature superconductor for energy. In the field of superconductivity in the real world—an area that has already seen five physics Nobel prizes—a Room Temperature Superconductor (RTS) is considered the “holy grail”. Superconductors are materials that, once cooled below a critical temperature, offer no resistance to electricity passing through them. Experiments currently running have currents persisting up to 23 years (as of August 2018), and scientists estimate that these currents can last up to 100,000 years.
Another essential feature of superconductivity is an expulsion of magnetic fields within the material—known as Meissner effect. So if a superconductor is placed in a magnetic field, it would repel it. This can then be used in phenomena such as magnetic levitation. Thus, superconductors could revolutionise many industries—power transmission, computing, transport.
For nearly 75 years after the Dutch physicist, Heike Kamerlingh Onnes discovered superconductivity, only metallic materials such as mercury and lead displayed this at temperatures below -243C. At these temperatures, liquid helium was necessary to keep the material cool enough, and as such was never practical.
In 1986, high-temperature superconductivity was discovered in certain “cuprates”—a class of compounds of copper and nitrogen. These materials displayed superconductivity at -135C, much higher than previously known superconductors. Liquid nitrogen could be used to cool these materials—a much cheaper and easily manageable refrigerant than liquid helium.
For physicists studying superconductivity, a room temperature superconductor that can be used without accompanying cooling infrastructure is the ultimate goal. This is what Cameron tapped into when he made unobtanium a room temperature superconductor in Avatar. Cameron uses RTS to beautiful effect in Avatar. The nature of unobtanium explains some of the most spectacular scenes in the movie. For instance, the majestic Hallelujah Mountains, full of unobtanium, float in the powerful magnetic pockets dotting Pandora’s surface due to superconductivity.
Cameron could not have chosen a more appropriate name. The awkwardly named mineral is also a tip of the hat to engineering jargon used in the real world, typically used for an ideal material that does not exist, but also for materials that are hard to come by. Spelt with an additional vowel —unobtanium —the first documented use comes from NASA’s structural engineers when they could not find a suitable high-temperature material.
n July 23, a research paper by Dev Kumar Thapa and Anshu Pandey appeared on arXiv—an online repository for research papers yet to be peer-reviewed. It looked like a corner had been finally turned on RTS.
The Thapa-Pandey paper claimed superconductivity at room temperature was possible in a nanostructure material they had prepared using silver and gold.
After the paper was uploaded, the story took a weird turn. Initially, the response was muted, with a few publications scrutinising the paper. Soon, a researcher at MIT found an anomaly in the data, suggesting not just that the results could be wrong, but that they could have been doctored. This set off a series of debates across social media—with scientists from India and outside debating the results vigorously. More drama ensued, as one discussion saw someone impersonating a senior Indian scientist. The impostor was asking people not to air their scepticism publicly.
The Thapa-Pandey experiments did not report superconductivity at room temperature. But -34C is still a much higher temperature than those reported previously. But the paper does say they can achieve room-temperature superconductivity.
Both Thapa, a PhD. student, and Pandey, an assistant professor, are from the Solid State and Structural Chemistry Unit at the Indian Institute of Science in Bengaluru.
To test for superconductivity, the material is either cast to film or compacted into pellets.
The test for superconductivity has two parts. In the first, the resistance of the material is tested as temperatures are lowered. At higher temperatures, the material showed resistivity, scarcely decreasing as temperatures were reduced. Below –27C, this resistance plunged suddenly to almost zero. Thapa and Pandey calculated that the critical temperature when resistance disappeared was around -34C.
The second part tested for diamagnetism. That is, below the critical temperature, the material should expel magnetic fields within it. Magnetic fields of varying strengths are applied to a pellet, and the magnetic field within the material is measured at different temperatures.
The Thapa-Pandey experiments did not report superconductivity at room temperature. But -34C is still a much higher temperature than those reported by semiconductors previously. Even in the title of their paper, Thapa and Pandey use ambient instead of room-temperature— “Evidence for Superconductivity at Ambient Temperature and Pressure in Nanostructures”.
But the paper does say they can achieve room-temperature superconductivity by tuning the nanostructure material to achieve zero resistance at “temperatures higher than room temperature”. While finer details of the composition and preparation of the material have been withheld, the paper explains that it is prepared using standard colloidal techniques.
These are centuries-old methods in which solutions are mixed under controlled temperature and pressure to form insoluble precipitates. After preparing the silver particles, they are embedded into a gold matrix. By changing the proportion of silver and gold particles, they were able to see low resistance and expelling of magnetic fields. But they were yet to see at what temperature this transition occurs.
or a paper that proposed a groundbreaking discovery, the initial reaction was mostly muted. The Hindu published a report on the piece, and The Wire published a detailed article looking at the science behind their work.
To be sure, this was a paper that was yet to be peer-reviewed or published in a journal. The authors also did not share all the data behind their experiments or even how to prepare the material. Writing In The Wire on August 6, two weeks after it appeared on arXiv, R. Ramachandran said: “The Pandey-Thapa preprint paper has not elicited any blog posts or other commentary thus far, which is somewhat surprising”.
Johnpierre Paglione, who directs a research group in the Center for Nanophysics and Advanced Materials at the University of Maryland, says RTS has been a driving force for research for many decades, and continues to be the "holy grail" achievement sought by many.
The results were surprising to him. “(G)iven that neither gold nor silver on their own show any trace of superconductivity down to the lowest temperatures ever measured. There is some theoretical understanding of why elemental gold and silver do not superconduct, making the claim of nanoparticle superconductivity very unexpected,” he wrote in an email to Fountain Ink
This unusual feature of repeated noise in the magnetic susceptibility has, to my knowledge, no precedent in the superconducting literature, and no obvious theoretical explanation.
On August 8, a new paper appeared on arXiv referring to the Thapa-Pandey paper. A little less than two pages long, the paper by Brian Skinner, a physicist at the Massachusetts Institute of Technology, closely examined a graph from the paper. Using software to extract data from the paper, he provides a zoomed-in view.
Now this graph—plotting “Volume Susceptibility” against temperature—essentially showed that, at or below the critical temperature of -34C, the nanomaterial expelled magnetic fields dramatically. Thapa and Pandey perform this experiment five times by applying differing strengths of magnetic fields.
Skinner noticed that two of these readings looked similar. If the readings at 0.1 Tesla were raised by a constant amount, it would match the readings at 1 Tesla (Tesla is the unit used for measuring magnetic field strengths). That is, the reading at 0.1 Tesla zigged and zagged at the same location as the reading at 1 Tesla. These zigzags implied that the noise was similar in the two readings.
This was unexpected. In two separate and independent measurements, it was highly unlikely that they would have the same amount of noise in them.
Skinner concludes by writing: “This unusual feature of repeated noise in the magnetic susceptibility has, to my knowledge, no precedent in the superconducting literature, and no obvious theoretical explanation.”
While Thapa and Pandey have refused to speak out on the issue, Skinner, in a tweet, said that the authors had reached out to him and acknowledged Skinner’s findings.
They took my comment in good faith, and their response is essentially:
“Thanks for pointing this out! We hadn’t noticed this peculiar noise correlation. We don’t know its origin yet.”
And that they were not backing from their claims
22/ I’ve had another email exchange with the authors, and I will just say:
They are REALLY not backing down from their claims.
They emphasize that they are focused on providing validation of their data, and will only post new data or a response to my note once they have done so.
n the paper in arXiv, Skinner himself did not mention fraud, but a day after the paper was posted, he did link it to the Schön scandal on Twitter. In 2002, the German physicist Jan Hendrik Schön, who had published a series of papers on superconductivity, was caught for research fraud after someone noticed the exact pattern of noise in different experiments. The Schön case has become something of a cautionary tale for those entering the research field.
T. V. Ramakrishnan, a senior physicist who has worked in superconductivity, says that Skinner’s finding is real.
While Skinner has been hesitant to call it a fraud, a few scientists, mostly outside India, have been more forthright. In a piece in Scientific American, Cornell University physicist David Muller is quoted as saying that it was game over. “It’s not hard evidence … but I know which way I would take a bet,” he says.
Paglione wrote to Fountain Ink that he thinks there is no doubt in Skinner’s discovery of repetitive noise patterns. “In itself, the highlighted noise patterns are indeed identical, and identical only in a partial range of temperature, and therefore highly suspect of fraud. Although it is always possible that a simple mistake was made, its hard to see how the measured data points of two independent sets would be identical only in a certain range and then be different near the transition”, he wrote.
“I am most surprised by the fact that it is so obvious and apparent”.
In a blog run by Science magazine, medicinal chemist Derek Lowe wrote that the implication should be obvious even to a casual observer. “That is, someone copy-pasted one of the lines, changed the colour of the points, and offset the new line a bit. If there were doubts about the validity of this report before this, they shrink into nothing compared to the doubts that people have now,” he writes.
“Think about it: if you were about to report a world-changing result like a room-temperature superconductor, wouldn’t you want to make sure that everything about the paper was solid?” he asks.
The time for niceties and feel good jingoistic statements are over. It is time the Quantum Condensed Matter community starts asking probing questions if we do not want to become a laughing stock internationally.
Within India, most scientists have been more guarded in their response. T. V. Ramakrishnan, a senior physicist who has worked in superconductivity, says that Skinner’s finding is real. “I understand that it is confirmed by the (subsequent) cross correlation analysis of the same data by Pandey (the senior author of the Thapa-Pandey paper),” he wrote to Fountain Ink.
He adds that the original discovery observations, as well as the noise patterns, must be looked upon by independent measurements.
Paglione says that the best evidence is reproducibility. “The best case would be for an independent group to reproduce a semblance of this result, even if the Tc value was much lower”, he says. He cites the example of high temperature superconductivity near -73C in hydrogen sulphide under high pressure a few years ago. “(T)he community called for further experiments to confirm the result, which was first reported by a highly reputable and well respected group of high pressure scientists”, he writes.
C. N. R. Rao, India’s most decorated living scientist, who has also worked on superconductivity, sent a brief response to Fountain Ink: “Pandey and Thapa should be looking into the problem of noise.”
he sharpest criticism from India has come from Pratap Raychaudhuri, who studies superconductivity at the Tata Institute of Fundamental Research in Mumbai. Raychaudhuri, who in 2014 was awarded the Shanti Swarup Bhatnagar Prize, a coveted award in multidisciplinary research in India, wrote a flurry of posts on Facebook.
On August 10, in a public post on Facebook, he wrote: “The time for niceties and feel good jingoistic statements are over. It is high time the Quantum Condensed Matter community starts asking probing questions if we do not want to become a laughing stock internationally.” Later, along with a link to Skinner’s tweets, Raychaudhuri wrote that “Thapa and Pandey realise that they have a moral obligation to respond to this. Their silence is not helping.”
Meanwhile, Thapa and Pandey have been quiet to respond to these allegations. Barring a few details of their exchange that Skinner made public, they have released similar statements to a few publications like The Telegraph, Vice Motherboard, and Nature’s news team.
The duo said that while the paper is under review at a journal, they would not comment on the details. Pandey has also told these publications that they were getting their results validated by independent experts, and they would announce them as soon as possible. “Without validation, the synthesis and device-fabrication details are speculative and will add to further confusion,” he is quoted.
The terms of engagement are slowly changing to a more open interaction. Papers are subject to scrutiny much more intensely, especially in cases where the claims are extraordinary.
Fountain Ink sent a mail asking for a timeline of when the validation would be complete, but there has been no response.
Even as these arguments were being made in public, a new incident hogged the limelight. On August 13, Raychaudhuri received an email from Ramakrishnan, in which he asked Raychaudhuri to stop criticising Thapa and Pandey. The mail also contained a trailing correspondence from Anshu Pandey which included his response to the Skinner paper.
In his reply, Raychaudhuri told Ramakrishnan that he should not form opinions based on second hand sources.
But this was the strange bit. While replying, Raychaudhuri noticed that Ramakrishnan had emailed him from an unfamiliar address, and copied his reply to his regular email address.
Later the same day, he received a call from Ramakrishnan who told him that he had not written such a mail. It was a case of impersonation. When Raychaudhuri checked his mail again, he found that the email was sent from a protonmail server—an encrypted mail server running out of Switzerland. The email address impersonating Ramakrishnan was email@example.com.
For the sake of healthy academic discourse, it is of paramount importance that Thapa and Pandey come out openly with their data and their samples. Their silence is harming the whole of Indian science.
On the same day, following Raychaudhuri’s post, Skinner reported that he had received a Facebook friend request from a person named Wiles Licher. Raychaudhuri also found out that he had received a friend request from the same account. The Licher Facebook account did not show much activity — it was about a month old, and there were a few one-sentence posts on Julius Caesar.
Soon after that, both the email account and the Facebook account were deleted.
eanwhile, a few have attempted to theorise why these similarities in noise in independent readings could exist. The most detailed account was given by Raychaudhuri. On August 12, he posted a short note on Facebook. He asks if the noise that is identified, is actually not noise, but part of the signal. He suggests that loosely compacted samples could be at play here, and the interaction with the applied magnetic field could explain many concerns raised in the Skinner paper.
He also suggests that this can be trivially verified: “At least two dozen labs in the country can do this measurement for Thapa and Pandey if they make their sample available,” he writes. And he reiterates his plea to Thapa and Pandey to share their data.
“For the sake of healthy academic discourse, it is of paramount importance that Thapa and Pandey come out openly with their data and their samples. Their silence is harming them, and in the process harming their institution and the whole of Indian Science,” he concludes.
With Thapa and Pandey maintaining a studied silence, and people within IISc tight-lipped, Fountain Ink has attempted to piece together how events turned out at IISc based on conversations with scientists and students at IISc and other Indian institutions. None of them wished to be named. Many have privately objected to the characterisation of the replicated noise as academic fraud. One researcher pointed to Pandey’s publishing record, calling him a “solid researcher and non-flamboyant.”
As per his Google Scholar profile, Pandey has published 41 papers since 2004—a fair publishing rate. In comparison, in just 2001, the year before his fraud was confirmed, Schön was listed as an author on a research paper every eight days.
Pandey’s paper is also still in the preprint stage, unlike Schön’s, which was found in published papers going back many years. “This could be a case in which the researchers genuinely made a mistake, not committed fraud,” says a student.
The student also pointed out that had Pandey wanted to commit academic fraud, he would not have chosen a Physics paper: “It would have been more likely for him to do it in his own field of Chemistry.”
This could also explain why Thapa and Pandey, a little unfamiliar with the world of physics, did not catch the similarity in noise levels.
“To commit academic fraud at this stage of his career would be career suicide,” said a researcher.
Fountain Ink also learned from second-hand sources that Thapa and Pandey discovered superconductivity in the material accidentally while working on Quantum dots. The low resistance surprised them initially and they thought there must be a mistake before actually verifying it.
Why are Thapa and Pandey cagey about sharing data? If the paper proves to be true, this is not just a Nobel-worthy discovery, but one that could prove lucrative.
Many had also said Thapa and Pandey have been sitting on the results for at least a year if not more before they submitted the paper for peer-review. Even before the scandal broke out they got an independent observer to verify the experiment—though it is not known who performed this and to what degree.
nother element of this saga is the role that pre-print repositories and social media play in the debate around academic research. A researcher at IISc, who spoke on condition of anonymity, says that increasingly, papers in fields like Biology and Physics are now being put up on pre-print repositories such as arXiv and biorXiv. “The terms of engagement are slowly changing to a more open interaction,” the researcher says. Papers are subject to scrutiny much more intensely, especially in cases where the claims are extraordinary.
For instance, in August, the New York Times published a story that claimed that a high level of engagement on Facebook was associated with a higher rate of anti-refugee incidents in Germany. The report was based on a research paper that was not yet published, and the Times was criticised widely on social media for basing it on a paper that was not peer-reviewed.
Why are Thapa and Pandey cagey about sharing data? Or provide details on how to prepare their material?
First is the issue of intellectual property. If the Thapa-Pandey paper proves to be true, this is not just a Nobel-worthy discovery, but one that could prove lucrative.
“If superconductivity were possible at room temperature,” says Ramakrishnan, “it would enter the home. For example, one could perhaps have room temperature quantum computers. And large-scale applications, imagined and unimagined, will follow. One could have lossless transmission of electrical power. Magnetic levitation trains running at speeds of hundreds of kilometres per hour could become commonplace.” Thapa and Pandey stand to gain big in monetary terms.
In such cases, it’s not uncommon for scientists to file for a patent for their discoveries. Reports suggest that Thapa and Pandey have applied for a provisional patent application. This also ties in with why they uploaded the pre-print on arXiv. This would give them an opportunity to claim prior art, in case someone else files for a similar patent.
Another reason for not sharing the data is to allow time for Thapa and Pandey to study the material thoroughly. At a meeting in Chandigarh where physicists were present to discuss the paper, Ramakrishnan recounted the discovery of a superconductor by physicists at the Tata Institute of Fundamental Research. In 1993, they had discovered a class of superconductors called quaternary borocarbides. But the discovery has been associated with American scientists who verified and characterised the material thoroughly.
Another incident closer home to Thapa and Pandey further illustrates this point.
In the Eighties, the Solid State and Structural Chemistry Unit at IISc, to which Thapa and Pandey belong, had come close to a Nobel in superconductivity. In 1986, two scientists at IBM’s Swiss lab found the first high-temperature superconductor belonging to a class of compounds called cuprates, for which they won the Nobel prize.
C. N. R. Rao, who had founded the department at IISc in the Seventies, had already worked on a similar family of compounds. Writing in Business Standard, P. Rama Rao said: “Alas, his work did not concern exactly that aspect the IBM researchers happened to investigate, winning the Nobel in 1987. Rao agonised over this incident but did not let up in his unrelenting pursuit of excellence, going on to make important contributions to high-temperature superconductivity and to several other facets of the new chemistry of materials”.
This article has been updated to include the reaction of Johnpierre Paglione from the University of Maryland.