  Electrodynamics of superconductors is primarily the electrodynamics of the
Meissner state, a state characterized by zero magnetic induction of a
superconducting fraction of conduction electrons. Simultaneously, the Meissner
state is characterized by zero resistivity and zero entropy of these electrons.
The latter means that the temperature of an ensemble of superconducting
electrons is zero as well. Understanding properties of the Meissner state
provides a key to understand and predict these and other equilibrium and
non-equilibrium properties of superconductors, e.g., properties of the
intermediate and mixed states, flux quantization, resistanceless transport
current, etc. The reader will see that all these properties have a single and
very simple origin: quantization of the angular momentum of the conduction
electrons combined into Cooper pairs, and that the electrodynamics of
superconductors and superconductivity as a whole is a magnificent manifestation
of the boundless ingenuity of Nature and of the power of Physics laws.
