This persnickety number determines the strength of magnetic fields. It figures in everything from motors and generators to audio speakers. Oh, and without it we’d live in eternal darkness.

The Earth’s magnetic field briefly collapsed, leaving life on Earth exposed to increased solar and cosmic radiation. This ...

The transverse Thomson effect is observed for the first time: current, heat, and magnetic fields generate controlled cooling ...

Water has always responded well to sunlight, evaporating faster under the sun than when heated by other energy sources. For ...