What Ever Happened to Superconductors?
Cold fusion and fifth-generation computers were among those technologies that in the 1980s were supposed to be on the verge of changing everything — but over three decades on have amounted to pretty much nothing.
In the same years one also heard a great deal about superconductors, specifically materials which, under appropriate conditions, cease to resist the passage of electrical current, so that it can flow absolutely without loss — becoming, as the name indicates, super conductors. That implies the possibility of enormous efficiencies in a very great deal of what we do with electricity — which can seem just about everything, with the list getting longer all the time.
In considering the publicity afforded the concept in the 1980s one should note that the concept was not new even then. The phenomenon of superconductivity was first observed way, way back in 1911. However, prior to the ’80s the known superconductors only worked at extremely low, near-absolute zero temperatures — which meant that they required enormous amounts of energy for refrigeration (especially with electricity passing through them and heating them up). This, of course, left them with little practical use — while achieving better than that was thought not only an engineering difficulty but a theoretical impossibility. What made superconductors seem newly relevant was the discovery of a ceramic (lanthanum barium copper oxide) that could work as a superconductors at relatively high temperature. (I stress relatively, because the ‘80s-era discovery meant superconductors operating at 90 Kelvin — which is about three hundred degrees below zero for those of us using the Fahrenheit scale.)
That may not seem very promising, but it did arouse expectations about the rate of progress in the field (there were fantasies that “superconductor supremacy” was going to very soon mean world economic supremacy) — which soon proved rather exaggerated. Still, the research effort continued, and happily, so does progress, with the use of different materials enabling them to achieve superconductivity achieved at higher and higher temperatures until, two years ago physicists actually achieved superconductivity at “room temperature” (in fact, achieved it at 58 degrees Fahrenheit, the average temperature in Bergen, Norway, in July and August) garnering significant attention back in 2020.
What has been less widely covered in the coverage aimed at a non-specialist audience has been the specific circumstances of the achievement of that superconductivity. The superconductor in question (a mix of hydrogen, carbon and sulfur) worked because it was under a pressure of 270 gigapascals — a figure more often mentioned than explained. Those unfamiliar with that unit of measurement should know that it is equivalent to well over 2.6 million times sea level atmospheric pressure, or under about 16,000 miles of water — which is to say, more than two thousand times the submarine hull-squashing pressure at the bottom of the Mariana Trench.
As this shows researchers in the field have traded one set of extreme conditions (cold) for another (pressure), so much so that those who imagined from the press reports that commercially useful room-temperature superconductors were imminent may, as is so often the case when looking more closely at pop science stories that make us think a technology at Technology Readiness Level 1 is already up at Level 9 find this a damp squib. But all the same, it is undeniably a breakthrough, proving that room-temperature superconductivity is, at least, possible, and perhaps yielding insights into how it might be achieved in less extreme conditions — while, for what it is worth, work has begun on making those superconductors work at lower pressures than that.
Moreover, it would be a mistake to think that this means that superconductors have amounted to as little as those other technologies previously mentioned have done to date. If without much fanfare, superconductors have already entered a wide variety of practical, everyday uses, with the most significant, perhaps, Magnetic Resonance Imaging (MRI) machines. Seventy percent of those installed worldwide use superconducting magnets to enable more rapid and comprehensive scanning of the patient. And in that we have a reminder of something else, namely that even short of room-temperature superconductivity the technology is being put to practical use, with another breakthrough previously thought an impossibility — a superconductor through which electricity flows in only one direction — opening the door to the use of the technology in computing to produce microprocessors hundreds of times faster than those operating today. Of course, the refrigeration requirements make our seeing this in consumer devices anytime soon implausible — but the head of the research team which made the breakthrough has himself argued for its possible applicability to server farms and supercomputers. If true, this could well prove revolutionary enough in itself.
Originally published at https://naderelhefnawy.blogspot.com.