On the description of financial markets: A physicist's viewpoint

The main concepts at the foundation of the so-called neoclassical description of financial markets are here scrutinized from a physicist's viewpoint [1, 2]. Indeed, in the last two decades, physicists have devoted an increasing activity to the scrutiny of ideas and concepts that are at the basis of that branch of economic theory customarily called neoclassical--at the foundation of the neoliberal doctrine--that appears to be culturally and politically dominating in the present hard times. This activity appeared as surprising in the early days of its rise and development, since the objects studied by physicists are usually atoms, molecules, planets or galaxies, that look quite different from the objects studied by social sciences, the queen of which is economics. Human beings, contrary to elementary particles or stars, are endowed with free will and, more important, the laws that rule the ways in which an individual makes her/his own choices and by which different individuals establish relations among them, developing a social behaviour, are unknown to us. Rather, it seems legitimate to doubt that such laws are well defined.