The infinite saga of superconductivity at room temperature

The infinite saga of superconductivity at room temperature

Achieving superconductivity at room temperature has been one of physicists' most ambitious goals for several decades. Succeeding would in fact mean opening the door to an infinite number of technological applications, reducing costs and increasing the efficiency of the production and transport of electricity. The goal is ambitious because it is very complicated to achieve. In fact, superconductivity is a property that some materials tend to exhibit at absolute zero, and which they lose quickly as the temperature rises.

The question is so important that it is the subject of a heated debate among professionals. In recent years, in fact, thunderous announcements and sensational denials have alternated, which have sometimes even bordered on accusations of fraudulent and unscientific conduct among colleagues. An endless saga that today is enriched with a new chapter. ArXiv, the pre-print server (i.e. a database into which articles are loaded before they are published in a peer-reviewed journal) most used by physicists, has removed several papers on the topic of superconductivity due to their "content" provocateurs and unprofessional language ”, and suspended for six months, as Science tells us, the account of one of the authors, Jorge Hirsch, theoretical physicist at the University of California, San Diego (Ucsd). Here's what's going on.

The great mystery of superconductivity at room temperature Achieving superconductivity at room temperature would be an unprecedented technological revolution. And some say they almost succeeded. But doubts and controversies are not lacking Read the article The previous episodes First of all, a contextualization and a summary of the previous episodes, starting from the science behind the question. In "normal" conditions (in this case we refer to the temperature) any material in which electric current flows presents a sort of "friction", the resistance, to the passage of charge carriers, which among other things leads to the development of heat by virtue of the so-called Joule effect.

Things have changed about a century last, when the German physicist Heike Kamerlingh Onnes discovered that in particular conditions (and we are talking about temperature), when one approaches absolute zero, the resistance of some materials suddenly clears to zero: these materials thus become superconducting, and the charge carriers flow through them without dissipating energy by friction. The problem is that, at the moment, we have not yet managed to replicate this mechanism in a convincing and incontrovertible way even at room temperature. Achieving this goal would allow to carry current in a much more optimized way, thus improving the efficiency of distribution by various factors. Here is the revolution we were talking about earlier.

And here are some of the skirmishes of recent times. In June 2019, a group of researchers from the Indian Institute of Science announced that they had developed a new nanomaterial based on silver particles encapsulated in a matrix of gold atoms that, according to them, turned into a superconductor. at temperatures well far from absolute zero.

Soon after, the American physicist Brian Skinner, one of the most ferocious protesters of the study, explained that he had identified in the data of Indian researchers a recurrent and suspected pattern of noise present both in samples analyzed than in those used as controls, which could indicate an error in the interpretation of the results or even a bad faith manipulation of the data. The question remained unresolved: the experiment was never repeated, and Skinner's questions are still unanswered.

A new attempt Let's move on to 2020. In October, Science published an editorial with the unequivocal title ( Superconductivity at room temperature finally obtained) in which it was told of an experiment during which a team of scientists, coordinated by Ranga Dias, physicist at the University of Rochester, said they had managed to synthesize a material composed of a mix of hydrogen, carbon and sulfur capable of showing superconductivity characteristics at room temperature. Provided, however, that the material itself is subjected to very high pressures, equal to about 2.5 million times the atmospheric one: another problem, in short.

This study also suffered the same fate as the Indian work, and this is where Hirsch enters the scene, who has repeatedly asked to check the raw data of the experiment and who, faced with the refusal of the authors ("Hirsch is a troll," they said, "and we are not going to feed him ['We are not going to feed this troll'] by giving him our data"), he exploded saying that the results are "probably fraudulent".

The last episode Volano rags, in short. So we are at the last episode, the most recent one, which saw Hirsch blocked for six months by arXiv. A very severe provision: “The suspension is unjust - he declared -. I can't work if I can't publish my articles ". As if that were not enough, other voices joined the debate, accusing arXiv of wanting to "stifle" the discussion. "Scientists who have the subject at heart, and who have the skills to be able to evaluate the experiments, on both sides - commented Nigel Goldenfield, a physicist from the same university of Hirsch in an email addressed to many colleagues - should be able to read and publish articles. Otherwise we risk going back years, when arXiv was a private community, where articles were not accessible to anyone ".

The response of the server administrators is that, in this case, it is not science that is in question: "In this whole story - explained Ralph Wijers, physicist at the University of Amsterdam and director of arXiv - not we have not even withdrawn an article because we did not agree with its scientific content. The problem is that people's emotions have come into play. There is too much acrimony ". The sentence that just did not go down to the moderators of arXiv was that relating to the accusation of fraudulent conduct, as well as the subsequent reply by the authors of the original article, defined as "full of provocative content and unprofessional language".

There is more: Hirsch himself later defended his opponents before the administrators of arXiv, writing to them that Dias "presented scientific arguments that the rest of the scientific community should be allowed to judge only on the basis of content, rather than conditioned by your arbitrary standards of decent language ”. In any case, at least until today, arXiv does not seem willing to retrace its steps. But we are sure that the story does not end there.

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