Superconductivity debunker: this physicist exposed flaws in a blockbuster claim
James Hamlin found problems with the work of controversial physicist Ranga Dias
This story is part of Nature’s 10, an annual list compiled by Nature’s editors exploring key developments in science and the individuals who contributed to them.
James Hamlin remembers the first time an experiment deceived him. As a graduate student, Hamlin saw signs of superconductivity — electrons flowing without resistance — in an unexpected material. Excited, Hamlin shared the news with his adviser, who was unfazed. “He asked me lots of questions and suggested lots of additional measurements,” Hamlin says. On further inspection, the superconductivity signal disappeared. The lesson he imbibed was straightforward: “Don’t assume you’ve discovered something,” Hamlin says.
That lesson played out on an international stage this year when Ranga Dias, a physicist at the University of Rochester, New York, reported in Nature in March that he had achieved the long-sought goal of room-temperature superconductivity, in a material held under moderate pressure.
Amid a furore of hype and criticism, Hamlin, a physicist who conducts high-pressure experiments at the University of Florida in Gainesville, and Brad Ramshaw, a superconductivity researcher at Cornell University in Ithaca, New York, sent Nature their concerns about the research. (Nature’s news team is independent from its journals team.) The paper was retracted in November, generating headlines: it was Dias’s third retraction in little more than a year.
This wasn’t the first or even the second time that Hamlin had exposed problems with Dias’s work. In 2020, Dias had published a paper in Nature that also claimed to have discovered the first room-temperature superconductor, albeit at much higher pressure. All known superconductors must be kept either extremely cold or at high pressures to function. One that works at ambient temperature and pressure might permit applications such as magnets for magnetic resonance imaging (MRI) that wouldn’t need expensive cooling equipment, and highly efficient computer chips — tantalizing possibilities that have led to hype around speculative claims of room-temperature superconductivity.
After Dias’s 2020 paper came out, Jorge Hirsch, a physicist at the University of California, San Diego, thought a measurement in that study looked iffy — and had similarities to a measurement in a 2009 paper that Hamlin had co-authored. Pushed by Hirsch, Hamlin investigated his own work and found evidence that another co-author, Matthew Debessai, had manipulated those data. (Debessai, who no longer works in research, didn’t respond to a request for comment.) That paper was retracted in 2021, but Hamlin wondered whether there were problems with Dias’s 2020 study as well.
It took more than a year for Dias and a co-author, Ashkan Salamat, a physicist at the University of Nevada, Las Vegas, to post the data Hirsch wanted. Analyses by Hirsch, Hamlin and others found evidence of manipulation. In September 2022, Nature retracted the work; the retraction statement did not mention misconduct, and Dias denied wrongdoing.
Hamlin also found that his own and others’ work had been plagiarized in Dias’s thesis — and that Dias had reused some of the thesis data in a later paper in Physical Review Letters. That paper was retracted this August. (Dias disagreed with the retraction, although he acknowledged not providing “explicit attribution” for some of his thesis.)
When Hamlin laid out his evidence at a virtual workshop this March, some observers were “stunned” at the work he’d put in, says Brian Skinner, a physicist at Ohio State University in Columbus and an organizer of the conference. At one point, unable to access raw electrical-resistance data, Hamlin created a tool to extract data directly from Dias’s graphs. “It was pretty heroic,” Skinner says.
This background of controversy was why many researchers were surprised that Nature published a second Dias paper in March, with another room-temperature superconductor claim, albeit in a different material.
This time, a lot of the raw data was public and questions quickly emerged online. Ramshaw and Hamlin focused on a few central concerns, including whether Dias had actually measured the electrical resistance going to zero.
In a subsequent back-and-forth involving Ramshaw, Hamlin and editors at Nature, Dias and his co-author Salamat did not explain how they had obtained this measurement. “We couldn’t get a square, straight answer on this very simple question,” Hamlin says. Nature’s news team reached out to Dias and Salamat for comment but did not receive any reply.
Then, in September, 8 of the paper’s 11 co-authors (including Salamat but not Dias) requested a retraction, corroborating concerns raised by Hamlin and Ramshaw. Nature retracted the paper on 7 November, citing concerns about data integrity.
Hamlin and Ramshaw say data availability made the latest retraction easier: it took only half a year, rather than two years.
Shanti Deemyad, a high-pressure experimentalist now at the University of Utah in Salt Lake City, supervised Hamlin in the laboratory when he was an undergraduate. She’s not surprised by his dedication. “He was very ambitious and very excited,” she says. “And he wanted to know all the details.” Even when she showed up to the lab as early as 6.30 a.m., Hamlin was there too, eager to learn.
Hamlin isn’t a full-time sleuth and is keen to spend more time on his own superconductivity research. “It’s still really the topic in physics that I find most exciting,” he says. “The BS of human beings is much less interesting to discover than the mysteries of nature.”
doi: https://doi.org/10.1038/d41586-023-03926-2
This story originally appeared on: Nature - Author:Dan Garisto
