In James Cameron’s 2009 blockbuster Avatar, humans are willfully exploiting the planet Pandora for a metal subtly named “unobtainium.” What could be so desirable that humans would theoretically be willing to destroy an alien culture to possess it?
As nerdy chatroom discussions have revealed, the fictional substance unobtainium is superconductive at room temperature—and the search for an equivalent is actually taking place.
Superconductivity means that a material (a metal, ceramic, or oxide) exhibits exactly zero electrical resistance. All materials naturally pose some resistance against the flow of electricity through their atomic structure, and unfortunately the slightest resistance causes some energy to be lost. The monstrous heat your ancient laptop shunts into your lap, for example, is waste from this resistance. An electrical current introduced to a superconductive material, on the other hand, would be used to its full potential without frying anybody’s eggs.
How does this occur? In a normal conductor, the electric flow is composed of electrons that behave like dour, negative lone rangers, independent of each other and even disgusted by close proximity. Unlike asocial outdoorsmen who are loners by choice, though, electrons literally can’t get near each other: magnetic rules apply to electrical charges, so a negative charge repels a negative and a positive repels a positive. Running solo through a material, some electrons crash into the atomic lattice, get absorbed, and converted into that wasted heat.
But in a superconductor, the material’s native atoms act as counselors and mediators for these rambunctious loners. Neighborhoods of atoms will join forces to exude some good vibrations, and with all this positive energy radiating over them, the electrons become social. Their natural negativity is reduced just enough so that they pair up, creating partnerships that improve the community as a whole. No longer do they race around recklessly, smashing into atomic telephone poles and creating waste—they flow smoothly, effortlessly, and (given that their environment forms a loop) infinitely.
As far as we know, any good conductor has the potential to be a superconductor, but it has to undergo grueling hardships before it can ascend to superhero status. It must undergo a trial of ice.
In 1911 Heike Kamerlingue Onnes, a Dutch physicist obsessed with freezing things, was liquefying and solidifying previously intangible gases like oxygen, hydrogen, and—the best coolant known—helium. Using liquid helium to cool a wire made of pure mercury to an unfathomable -452 degrees Fahrenheit, he saw the metal turn superconductive. Scientists later learned that the frigid temperature reduced quantum vibrations in the wire’s atomic lattice that would normally encourage disruptive electron behavior. The chilled, stilled lattice produced that proactively positive environment that influenced electrons to partner up—the proper stage for zero electrical resistance.
What prevented Onnes and other physicists from plugging superconductive materials into every machine possible is that -452 degrees Fahrenheit is a ridiculously difficult temperature to achieve and maintain on anyone’s paycheck. A related limitation is that helium exists in very limited and dissipating quantities on our planet. Thus, cooling materials to their superconductive states with something as expensive and rare as liquid helium was out of the question for the regular Joe.
The humans’ excitement in Avatar may be easier to understand now. Having a room-temperature superconductor means extremely efficient circuitry with no effort, no large price tag, no witchcraft. We’d simply replace our copper wires with unobtainium.
The pursuit for a room-temperature superconductor continues, but so far only a few “high-temperature” candidates have been found. These variants, usually a mixture of metal oxides or ceramics rather than pure elemental metals, achieve superconductivity around -200 degrees Fahrenheit. While this critical temperature is attainable with the more available liquid nitrogen, the oxides or ceramics themselves tend to be brittle, limiting the actual instruments that can be made with them.
In the meantime, we have been able to use superconductors to create unnaturally large, stable magnetic fields. Moving streams of electrons create magnetic fields, and a coil of superconductive metal is effectively an empty vessel that can hold a massive electrical current without the fluctuations and energy loss that come with resistance. A magnetic field’s size and strength is proportionate to its parent current, and the sheer power of the magnetic fields we can now generate resembles magic.
What do we use it for? We’re not quite at the level where we can levitate mountains, but we do have maglev trains: trains that are electromagnetically suspended above steel rails. We also have MRI machines, which use the strong magnetic fields to create a magnetic echo in the atoms of our bodies so we can map our insides without a single cut or stitch. And the more we tinker, the more uses and mysteries we’ll find.
Superconductivity may sound like a plot device in a science fiction story, but its potential is real. Its properties are already being utilized all around us. But with unobtainium, the superhero to champion energy efficiency and sustainability, the technological gizmos of Star Trek and the unbridled potential of Magneto would be within reach—hopefully, though, without the possible alien genocide.