|Humorous attempt at applying Isaac Newton's three laws of motion to the understanding of human relationships by cartoonist Scott Meyer. |
An early attempt, albeit new age styled, non-scientific, at a book on the subject of applying physics to the understanding of love and or relationships is the 1996 The Physics of Love, by Edgar Cayce, Dale Pond, and Rudolf Steiner, a summary of the 19th century metaphysics of inventor John Keeley (1827-1898).  Keeley, supposedly, is noted for his 1871 claim that he had tapped a great new source of energy and "a device which disintegrates the etheric force that controls the atomic constitution of matter." Keely claimed that his engine operated on "harmonic vibrations." Some of his machines would only operate in his presence. Keeley also made a particular spherical motor which was supposed to run on etheric forces.  The book seems to be have attracted the new-age spiritual energy crowd movement.
Hirata's physic of relationships
In c.2000, American physicist Christopher Hirata published a five-part outline entiled "Physics of Relationships", consisting of: 
(a) thermochemical approach to relationships
(b) complex equilibria of man and women
(c) reaction kinetics
(d) neutron scattering
(e) shell model
To go through part (a), the thermochemical aspects of relationships, Hirata uses the student body at Caltech, observed during this undergraduate years (1996-2000), which he says consisted of N=900 total students, of which 600 were male, and according to his observations about 200 were in paired relationships. He uses the symbols of X = girl, Y = boy, and XY = paired relationship, calling the single boys and girls as “basic elements”, of which he says the simplest reaction is:
X + Y ↔ XY
Hirata also comments, in reference to the subject of queer chemistry (and other poly-amorphous relationships), in his human chemical reaction modeling that he is neglecting “rare and non-traditional” products or compounds (human molecules) that may form such as “the gay molecule Y2, the lesbian molecule X2, and the middle-Eastern polygamous molecule X4Y.” On this basis he states that the equilibrium constant K for this reaction is:
where [X], [Y], and [XY] are the concentrations of the single girls, single boys, and paired relationships, respectively. This constant, according to Hirata, can be calculated from the following expression:
where KB is the Boltzmann constant, T the temperature, ΔE the internal energy change, ΔV the volume change, and ΔS the entropy change at standard conditions. He goes on to calculate that KB at Caltech is 4.5. On this basis, he goes on to calculate, assuming that the equilibrium constant is independent of concentration and is a function of only temperature and pressure, that if the female to male ratio were 50:50 the percentage of singe males would drop from 67% to 48%.
|Rendition of Ecob's radioactive decay model of dating by Stacy Innerst. |
Ecob's radioactive decay model
In 2005, Oxford undergraduate physicist student Richard Ecob developed a atomic radioactive decay model of how people look for partners.  Specifically, Ecob conceived the view that anyone’s romantic life can be reduced to a series of transitions, or ‘transit states’, e.g. ‘twice-divorced and now single’. This may be considered as nuclear model of chemistry's transition state theory.
To understand this in physic terms, he looked to the model of how the decay of a nucleus is described in terms of ‘transit states’, the series of changes it has been through to get to its current situation, i.e. the stages of radioactive decay. In applying this to human situations, Ecob wrote a computer program in which he created an artificial society of partner-seeking-people called ‘software singles’.  The project, as of 2005, was part of Ecob’s MS thesis, working with graduate student David Smith and their supervisor Neil Johnson, head of the complex systems research group at Oxford University. The project was also entered into the 2005 Engineering and Technology Student of the Year awards.
The following are related quotes:
“Physics is like sex. Sure, it may give some practical results, but that’s not why we do it.”— Richard Feynman (c.1950)
● Relationship chemistry
● Social physics
1. Cayce, Edgar, Pond, Dale, Keely, John, and Steiner, Rudolf. (1996). The Physics of Love: the Ultimate Universal Laws. Message Company.
2. Hirata, Christopher M. (c. 2000). “The Physics of Relationships” (section: Fun), Tapir.Caltech.edu.
3. Meyer, Scott. (2007). “How to Apply the Laws of Physics to Personal Relationships”, Apr 10, BasicInstructions.net.
4. Anon. (2005). “Physics Enlisted to Help Singles”, BBCNews, Aug 12.
5. Anon. (2005). “If Chemistry Can’t Make a Great Date, Physics Will.” Press Release, World Leadership Forum.
6. Leo, Peter. (2005). “Successful Couples need Good Physics, but what about Paternal discrepancies” (photo by Stacy Innerst), Pittsburg Post Gazette, Aug. 16.
● The relationship between quantum physics and love – Helium.com.
● The Physics of Sex – Blogspot.com.
● John Marshall (articles) – SexualPhysics.com.