Human physics (Jack and Jill)
A jack and Jill stylized version of Newton's cradle, illustrating the conceptual model of human physics as the physics, e.g. laws of motion, applied to people.
In science, human physics is the study of people, viewed or modeled as "human particles", interacting socially, using the principles and laws of physics; in general, the use of physics models to explain human patterns. A number of variations of this field exists, including: social physics, sociophysics, econophysics, among others.

The term “human physics” was coined in 1835 by Adolphe Quetelet. Later synonyms include: Humanized physics (Edwin Slosson, 1910), Anthropic physics (Wilhelm Ostwald, 1912), among other variants on the same general subject, albeit with different names (see: two cultures namesakes).

See also: HP pioneers
The starting point for the subject of "human physics" is generally considered to be the publication of English science philosopher and political theorist Thomas Hobbes’ 1651 book Leviathan, in which he draws analogies between laws of mechanics and features of society. Hobbes was greatly influenced by the newly forming field of physics and even travelled to Italy to meet the aging physicist Galileo Galilei. [5]

A classic 20th century example of human physics is the the 1970s work of Australian mechanical engineer Roy Henderson who monitored the movements of college students on a campus and children on a playground, finding that in both cases their movements fit the Maxwell-Boltzmann distribution, meaning that both velocities of gas particles and the speeds of students follow a Gaussian distribution. [1]

American theoretical physicist Mendel Sachs’ 1993 book Relativity in Our Time: From Physics to Human Relations, is a type of human physics focused on the philosophy of relativity theory and its extension from physics to the field of human relations and relationships. [3]

Some of the more recent work by social-physical science analogy theorists, such as Malcolm Gladwell on tipping points (2000), Mark Buchanan on power laws (2000) and social atoms (2007), Philip Ball on critical mass (2004), Len Fisher on crowd and swarm behavior (2009), among others, might be considered as ‘human physics’.

American mechanical engineer Adrian Bejan's 2007 constructal theory used to the explain social dynamics and branching flows is often characterized loosely as human physics. [2]

A recent example of human physics is the study of the force of attachment between humans, in terms of the fundamental forces, e.g. field particle exchange models.
Crowd dynamics
A type of human fluid like crowd dynamics simulation model, often employed in human physics, to study designs in emergency situations, e.g. fire, bomb threat, etc.

Crowd dynamics
A recent popular subject in human physics is crowd dynamics the study of "crowd behaviors" in particular abnormal crowd behavior such as people's reactions and movement patterns in the case of emergencies, such as fire, wherein people as particles and crowds as fluids or flows of particles. [7]

Shown adjacent are depictions of fluid or particle system models of crowd behavior, e.g. exodus system, panic simulation system; some of which, however, are nearly incoherent in their anthropomorphism, such as those extolled by Scottish mathematician Keith Still: [7]

"The laws of crowd dynamics have to include the fact that people do not follow the laws of physics; they have a choice in their direction, have no conservation of momentum, and can start and stop at will."

which, of course, is completely backwards in logic: everything in the universe follows the laws of physics except humans?

Because of the fact that improper building design has often lead to many deaths that could have been avoided, human physics models, formulations, and computer simulations can often have a real-world impact. The following diagrams, for example, outline some various diagrams of human flow movements, each entity modeled as a human particle: [7]

The following are noted human physics related or themed quotes:

Love is a matter of chemistry, but sex is a matter of physics.”
– anonymous (or attributed to a Dr. John Marshall) [6]

See also
Human thermodynamics
Human chemistry

1. Henderson, L. F. (1971). “The Statistics of Crowd Fluids”, Nature, 229: 381-83.
2. Anon. (2007). “Theory of Physics Explains Human Patterns”, Duke University,, Jun 12.
(a) Sachs, Mendel. (1993). Relativity in Our Time: From Physics to Human Relations (abs). CRC Press.
(b) Mendel Sachs – Wikipedia.
4. Bejan, Adrian and Zane, J. Peder. (2012). Design in Nature: How the Constructal Law Governs Evolution in Biology, Physics, Technology, and Social Organization. Doubleday.
5. Wakeling, Joseph. (2007). “Book Review: Critical Mass: How One Things Leads to Another, Jul 16, EconoPhysics Forum.
6. (a) Gaither, Carl C. and Cavazos-Gaither, Alma E. (2002). Chemically Speaking: a Dictionary of Quotations (pg. 123). CRC Press.
(b) The Physics of Sex (2007) –
7. Pan, Xiaoshan, Han, Charles S., Dauber, Ken, and Law, Kincho H. (2005). “Human and Social Behavior in Computational Modeling and Analysis of Egress”, Automation in Construction, 15(4): 448-461.

Further reading
● Bagehot, Walter. (1873). Physics and Politics. D. Appleton.
● Rowe, Alan R. (1982). Social Physics and Cultural Sociology: a Primer of two Typologies for Masters of Sociological Thought. University Press of America.
● Restivo, Sal. (1985). The Social Relations of Physics, Mysticism, and Mathematics. Springer.
● Weidlich, Wolfgang. (1991). “Physics and Social Science: the Approach of Synergetics” (abs), Physics Reports, 204(1): 1-163.
● Castellano, Claudio, Fortunato, Santo, and Loreto, Vittorio. (2009). “Statistical Physics of Social Dynamics” (abs), Rev. Mod. Phys. 81: 591-646.

External links
Physics and society (publications list) –, Cornell University.

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