Related work to psychohistory is being performed in the budding Physical History and Economics (PHE) field, using Fast Entropy as the primary driver, and considering psychological consequences as dynamic functions of the reaction of human nature to this primary driver.

The Principle of Fast Entropy (also called the e th Law of Thermodynamics) states that systems tend to configure themselves to maximize the RATE of entropy production and thus drives exponential growth. The resulting tendency of societies to grow exponentially in the face of limited resources and decreasing efficiency can be used to model the rise and fall pattern seen in major historical dynasties. Unfortunately, most people find the Principle of Fast Entropy to be quite emotionally upsetting, but the project can't find anything more fundamental yet. Utilizing thermodynamics has the advantage of bringing the social and physical sciences under a unified framework. Hopefully there will be some sympathy on this site for such a unification, because there isn't much appreciation of such elsewhere!

Although thermodynamics provides overall constraints, human psychology provides additional constraints; PHE views social science as a balancing of such constraints.

Fast Entropy/Physical History and Economics is not yet a large field, but it has been circulating in aerospace circles and among technocrats. (Some of the work is derived from Technocracy, Inc. cofounder's M. King Hubbert's work on peak oil.)

Psychohistory and PHE share much. One difference is that Asimov's psychohistory does not seemed to be constrained by energy (his work early works were written when energy prices were much less). However, the probabilistic approach i quite similar. PHE is certainly not yet as well developed in psychology as Asimov's psychohistory. Still, it is hoped that there will be much synergy between the fields.