Superconductivity occurs when electrons in a metal pair up and move through the material without resistance. But there may be more to the story than we thought, as scientists in Germany have now discovered that electrons can also group together into families of four, creating a new state of matter and, potentially, a new type of superconductivity.

Conductivity is a measure of how easily electrons (and therefore electricity) can move through a material. But even in materials that make good conductors, like gold, electrons will still encounter some resistance. Superconductors, however, remove all such barriers and provide zero resistance at ultracold temperatures.

The reason electrons can move through superconductors so easily is because they pair up through a quantum effect known as Cooper pairing. In doing so, they raise the minimum amount of energy it takes to interfere with the electrons – and if the material is cold enough, its atoms won’t have enough thermal energy to disturb these Cooper pairs, allowing the electrons to flow freely with no loss of energy.