The Week in Space and Physics: Superconductivity in the Spotlight
On superconductivity, volcanoes on Venus, Virgin Orbit and the Earth's innermost core
Along with nuclear fusion and quantum computing, room temperature superconductivity is one of the holy grails of physics. In theory, it could revolutionise the world, ushering in an era of ultra-efficient electrical devices. Yet in practice, like nuclear fusion and quantum computers, superconductivity has proven hard to pin down.
At low temperatures - that’s to say, a few hundred degrees below freezing - superconductivity is well established. It appears as a quantum phenomenon in certain materials. When they are cooled below some “critical” temperature - exactly what depends on the material - they lose all electrical resistance. That unlocks all sorts of bizarre properties. Indeed, one favourite trick of physicists is to show off superconductors levitating above magnetic tracks.
These properties could be exceedingly useful in the real world. Sadly, though, all known superconductors only work at freezing temperatures or under huge pressures. Since nothing seems to outlaw superconductivity at higher temperatures, physicists have spent decades looking for a material that works at close to room temperature and pressure.
On March 7 that appeared to change. Ranga Dias, a researcher at Rochester University, claimed to have discovered a superconductor that worked up to 21°C. As reported, the material is impressive: potentially opening the door to a realm of new technologies. Yet, as always, the claim has become rather controversial.
For one thing Dias has been here before. He made an earlier claim of room temperature superconductivity in 2020, but was forced to withdraw it after other researchers spotted flaws in his analysis. That, of course, doesn’t mean he is wrong again - but it does mean the claims should be approached with some skepticism.
For another, efforts by other researchers to repeat the experiment have failed to find signs of superconductivity. These results are early of course - Dias only announced his work two weeks ago - but they are not encouraging.
Reactions from other researchers have been mixed. While many praised Dias’ work, and pointed out that it would be a groundbreaking discovery, others were much more critical. Commenters on Nanoscale Views, a blog covering the normally calm world of condensed matter physics, were quick to pour scorn on Dias’ claims.
Dias, for his part, has been sticking by his claims. He has been working on resubmitting his earlier retracted paper, this time with the errors fixed. He has also invited independent researchers to his lab, and asked others to replicate his work on superconductivity. That, in the end, may prove enough to clear his name.
But if not, he seems to be playing for extraordinary stakes by submitting another claim of room temperature superconductivity. Media attention on the subject is already rising. Should it turn out that the results are once again wrong, then room temperature superconductivity could suffer a harsh fate, perhaps even akin to earlier claims of cold fusion. Should he be correct, however, the discovery would be nothing short of revolutionary.
Volcanoes on Venus
Long ago, before any probes had visited Venus, scientists imagined it to be a lush tropical world. It would be hot, they thought, but not so hot as to be uninhabitable. Indeed, the higher temperatures might even be beneficial for life - allowing creatures to flourish in jungles and tropical seas.
The first missions to visit quickly put an end to those ideas. Venus turned out to be a literal vision of hell. Temperatures on the surface soar to hundreds of degrees, while its atmosphere is a choking fog of sulphuric acid and carbon dioxide. So hostile is the planet that even robotic visitors die within minutes.
Venus is thus much less explored than Mars, even though it is far closer to Earth. The question of whether the planet still has active volcanoes, for instance, has puzzled planetary scientists for decades. When the Magellan probe visited in the early 1990s, it mapped out hundreds of sites that looked strongly like volcanoes. Indeed, there seem to be far more of them than even Earth has.
Yet it was unclear if any of these volcanoes still erupted, or if the planet’s geology had long ago ground to a halt. Over the years since, some intriguing hints that they do has emerged. Subtle changes in Venus’ atmosphere have been detected, and brief flashes of heat have been observed on its surface. These, some think, are signs of volcanic eruptions.
Now a new study claims to have found stronger evidence by re-examining images captured by Magellan. As the probe orbited Venus, it repeatedly mapped out its surface, returning several images of the same sites. By comparing such images, researchers at JPL and the University of Alaska Fairbanks were able to spot slight changes around some suspected volcanic vents.
These changes, they say, are probably the result of eruptions: strongly suggesting that volcanoes are indeed still active on the planet. Yet the images are not always clear, and often have low resolution. A final answer to the question will probably only come when a new probe heads to Venus.
Virgin Orbit Suspends Activities
Two months ago Virgin Orbit looked to be flying high. As it prepared for the first orbital launch ever to take place from the United Kingdom, the company was fêted by the British government. Even Prime Minister Rishi Sunak tweeted in support, wishing the company good luck in its efforts.
And, indeed, as the company’s Boeing 747 took off from Newquay airport, a rocket slung securely under one wing, success seemed close. Sadly, it was not to be. The rocket, deployed from the aircraft, failed to reach orbit: suffering an engine problem that left it to fall into the depths of the Atlantic Ocean.
Soon after, reports emerged claiming Virgin Orbit was suffering financial problems. Richard Branson - the company’s founder - appeared reluctant to invest more funds. A financial report in November showed cash reserves of just $70million - enough, analysts predicted, to last until March.
That assessment may now have been proven correct. Virgin Orbit last week suspended activities, furloughing its staff. Cash flow issues were to blame, the company said, and it would be seeking further investments in the hope of restarting work before long.
Regardless of whether the January launch attempt had succeeded, it seems likely Virgin Orbit would have ended up in this situation before long. Its price per launch - around $12 million - seems too low to sustain a business spending over $20 million per month. That, in turn, may highlight the challenges facing many rocket companies as they compete for limited demand in an ever more crowded market place.
Earth’s Inner Inner Core?
Two decades ago, studies of seismic waves hinted that the Earth’s inner core - a ball of solid iron and nickel measuring seven hundred miles in diameter - was more complex than we thought. Those seismic waves seemed to take longer to cross the core when coming from certain directions, a detail that suggests the core has some kind of internal structure of its own.
Researchers are still not sure exactly what this is, but new research has recently strengthened this idea. Once again they found waves coming from one direction - that tilted roughly fifty degrees from the Earth’s rotation - took slightly longer to cross the core.
Their findings suggest the inner core has a shell-like structure. In its centre appears to be a metallic ball measuring roughly four hundred miles across. Around it lies a second shell, some three hundred miles wide. Quite why this should be the case is unknown. Perhaps the iron crystals in the core arrange themselves differently closer to the centre of the planet. Or, perhaps, some long ago event split the core in two, leaving a long lasting scar across the heart of the planet.