In economics, physical economics is the study of economic phenomenon from the point of view of physics.
Near synonyms to the term “physical economics”, although subtle variations may exist, include: physioeconomics, thermoeconomics, biophysical economics, and economic thermodynamics.
The coining and attribution of the term “physical economics” seems to have been first dominantly introduced in a set of two early 1880s papers by Scottish thinker Patrick Geddes, who incorporated some of the earlier thermodynamics work of Scottish physicist Peter Tait to outline a comprehensive attempt to enumerate the physical and physiological principles of economic science.  These two papers by Tait and Geddes, according to a 1901 review by Victor Branford, are said to mark the start of the invasion of physics into the territory of economics. In these papers, Geddes is said to have argued that “goods” should be considered as matter and energy, both quantitatively and qualitatively, and expressed in terms of mechanics and chemistry. The passage best representative of Geddes’ version of physical economics is as follows: 
“The economist having reached the conception of the processes of production and consumption as one vast mechanical process; the view of society as a machine in which all phenomena are interpreted as integration or disintegration of matter, with transformation or dissipation of energy .... it is legitimate, nay inevitable, to apply the quantitative conceptions of physics— the modern measurements of matter and energy— .... that measurement in terms of units of energy as well as of units of , weight is practicable, and this physical conception once introduced its extension to all processes must be attempted. For the treatment of this only one other consideration need be pointed out, the possibility of expressing the labour of the producer automata, just as we do that of the ordinary machines with which they are so largely interchangeable: the horse-power of an engine is easily translatable into man-power, might indeed always have been so expressed; this granted, the conception of man-day .... and its multiples (man-year, man-life) with the higher multiples of these can all be approximately stated .... The physical economist then has means of measurement and comparison other than that afforded by money—his units are really the metre and the kilogram of the physicist—and only when some quantitative data in these terms are approximately reached, will those expressed in money be really capable of interpretation."