Superconductors are materials that conduct electricity with no resistance. The phenomenon was first discovered by Dutch physicist Heike Kamerlingh Onnes, who in 1911 saw mercury’s resistance drop to zero at 4.2 degrees above absolute zero. Other materials were found to be superconducting at slightly higher temperatures, but the need for extreme refrigeration limited the usefulness of the phenomenon.
Until 1986, that is. That was when we discovered the high temperature superconductors, which abruptly stop resisting below roughly 100 kelvin (which is -170 °C: the term “high temperature” is a relative one). Suddenly, creating room temperature superconductors didn’t seem so far-fetched.
That second great leap forward hasn’t happened – yet. So far we have not bettered what we found 30 years ago, says Paul Attfield of the University of Edinburgh, UK. Materials have been discovered that superconduct at somewhat higher temperatures, but only when under extremely high pressures.
For now, superconductors remain entirely impractical for the killer applications that would allow them to change the world: transport and electrical power transmission.