The
London equations, developed by brothers
Fritz and
Heinz London in 1935, relate current to
electromagnetic fields in and around a
superconductor. Arguably the simplest meaningful description of superconducting phenomena, they form the genesis of almost any modern introductory text on the subject. A major triumph of the equations is their ability to explain the
Meissner effect, wherein a material exponentially expels all internal magnetic fields as it crosses the superconducting threshold.