In 1911, when scientists were first experimenting with extreme cooling techniques, Dutch physicist Heike Kamerlingh Onnes discovered something remarkable about the way that certain materials conduct electricity. He observed that simple elements like mercury can conduct electricity with zero resistance once the temperature drops below a specific threshold.
At low temperatures, these materials become perfect conductors of electricity—hence the name “superconductors.” In a closed loop of superconducting material, an electrical current would be able to flow around forever without losing any energy.
Superconductors become even more intriguing once you place one on top of a strong magnet. The strong magnetic field causes an internal magnetism to be induced in the superconductor, which is then repelled by the magnet underneath. This magnetic repulsion results in the superconductor defying gravity and floating in midair like a miniature hoverboard.
Japanese engineers have even built a railway system that runs on this exact principle. The SC Maglev trains—short for “superconducting magnetic levitation”—have superconducting magnets instead of wheels. They are cooled using tanks of liquid helium and levitate 10 centimeters (4 in) above a long magnetic track. In April 2015, the high-speed L0 Series SC Maglev train set a world record for rail travel of 603 kilometers per hour (375 mph) at a test track near Mount Fuji.[
Currently, all known superconductors will only operate in extreme cold, which means they have a fairly limited range of uses. Even the most complex superconducting materials like yttrium barium copper oxide lose their superconductivity once the temperature rises above -173 degrees Celsius (-279 °F). The challenge now facing scientists is to find a way of retaining these superconductive properties at room temperature.