A research group led by a scientist at the U.S. Department of Energy's Brookhaven National Laboratory has discovered a simple relationship that mathematically links the properties of a class of high-temperature superconductors, materials that, below a certain temperature, conduct electricity with no resistance. This new, unexpected law applies to superconductors with very different structures and compositions, and may provide clues to understanding the mechanism of high-temperature superconductivity. It is discussed in the July 29, 2004 issue of Nature.