The American middle class has shrunk in size since 1970 according to most definitions. This “hollowing” out of the United States income distribution could result in disillusionment, diminished political engagement, and declining trust in institutions. The American middle class faces two...

The present review is based on the lectures that the author had been giving during several years at the Swiss Federal Institute of Technology in Zürich (ETH Zürich). Being bounded by lecture frames, the selection of the material, by necessity, is limited and is motivated by the author’s...

This review article is the second part of the project 'Selected Topics of Social Physics'. The first part has been devoted to equilibrium systems. The present part considers nonequilibrium systems. The style of the paper combines the features of a tutorial and a review, which, from one side,...