||An approach that suggests aggregate human interaction over space can be explained and predicted using physical theories and laws. Implicit within such a view is theoretical monism, one where a single explanatory principle holds for both physical and social processes alike.
H.C. Carey (1858) first codified social physics when he proposed that use be made \'â€¦ of the great law of molecular gravitation as the indispensable condition of â€¦ man [sic]\'; a suggestion that was subsequently empirically supported by E.G. Ravenstein\'s (1885) early work on migration. W.J. Reilly (1931) presented the first mathematical formulations in his study of retail trade areas (cf. applied geography; hinterland; retailing, geography of), but it was primarily J.Q. Stewart (1950), professor of astronomy and physics at Princeton University, who systematically worked through the analogy between interacting particles and interacting humans. During the late 1950s, Stewart, along with W. Warntz (1965), prosecuted social physics under the rubric of macrogeography, a short-lived movement but one that paved the way for the subsequent success of spatial science within human geography (exemplified by the quantitative revolution and regional science).
The gravity model remains the best-known exemplar of social physics. Drawing an analogy with Newton\'s law of gravitation, it is assumed that humans interact over space as do heavenly bodies in the celestial system. In this formulation, interaction between places is directly proportional to the product of their masses (usually measured by population size) and inversely proportional to some function of the distance between them. The gravity model, along with other social physical analogies such as population potential, diffusion, and entropy-maximization models, have been extensively tested. They often give good empirical fits, but are less satisfactory in their predictions, and even worse in providing explanations.
The lack of explanatory purchase, as Lukermann (1958) pointed out in an early critique of social physics, is because the assumptions made in the physical models are not met in the human realm: \'the lacuna is of the order of two worlds\' (Lukermann, 1958, p. 2). There is nothing wrong with analogies per se, but for them to succeed there must be certain core similarities between the analogy and the analogized. For many critics of social physics the similarities between human and celestial movements are not just hard to find, they are simply not there to be found.Â (TJB)
References Carey, H.C. 1858: Principles of social science. Philadelphia: J.B. Lippincott.Â Lukermann, F. 1958: Towards a more geographic economic geography. Professional Geographer 10: 2-10.Â Reilly,W.J. 1931: The law of retail gravitation. New York: W.J. Reilly.Â Ravenstein, E.G. 1885: The laws of migration. Journal of the Royal Statistical Society 48: 167-235.Â Stewart, J.Q. 1950: The development of social physics. American Journal of Physics 18: 239-53.Â Warntz, W. 1965: Macrogeography and income fronts. Philadelphia: Regional Science Research Institute.
Suggested Reading Barnes, T.J. 1996: Logics of dislocation: models, metaphors and meanings of economic space. New York: Guilford, chs 4 and 5.Â Lukermann, F. and Porter, P.W. 1960: Gravity and potential model in economic geography. Annals of the Association of American Geographers 50: 493-504; Stewart (1950).