In existographies, Mark Granovetter (1943-) (CR:14) is an American sociologist noted, in human chemistry, for his 1969 theory that "weak ties" between people in social networks are akin to hydrogen bonds between water molecules; the following being his basic model:

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Overview
In 1969, Granovetter conceived of a ‘weak ties’ hydrogen bonding based model of intermediate strength social connections, based on chemical bonding theory, particularly the model of the 'hydrogen bond', from Granovetter's undergraduate chemistry class, a theory which he published in the famous and highly-cited 1973 article "The Strength of the Weak Ties". [1] Granovetter’s weak ties theory was stimulated, in part, by the 1954 view of Russian mathematical psychologist Anatol Rapoport that:

“It is a well-known fact that the likely contacts of two individuals who are closely acquainted tend to be more overlapping than those of two arbitrarily selected individuals.”

In Granovetter’s theory, this has come to be known as ‘triadic closure’, stated as follows: “If two people in a social network have a friend in common, then there is an increased likelihood that they will become friends themselves at some point in the future.” [6]


In the liquid state, freely floating water molecules associate with each other through ‘hydrogen bonds’ in which part of the negative charge (2δ-) of the oxygen atom (shown in red) from one molecule stabilizes in bonding interaction, via an exchange force, with part of the positive charge (δ+) of hydrogen atoms from another water molecule; creating a loose tetrahedral binding geometry in the structure of the associative bonds.

In the liquid state, freely floating water molecules associate with each other through ‘hydrogen bonds’ in which part of the negative charge (2δ-) of the oxygen atom (shown in red) from one molecule stabilizes in bonding interaction, via an exchange force, with part of the positive charge (δ+) of hydrogen atoms from another water molecule; creating a loose tetrahedral binding geometry in the structure of the associative bonds.

Hydrogen bonds
In the late 1960s, to obtain data for his doctoral thesis at Harvard University, Granovetter interviewed dozens of people to find out how social networks are used to land new jobs. Granovetter found that most jobs were found through "weak" acquaintances. This pattern reminded Granovetter of his freshman chemistry lesson that demonstrated how "weak" hydrogen bonds hold huge water molecules together, which are themselves held together by "strong" covalent bonds. A similar combination of strong and weak bonds, according to Granovetter, holds the members of society together.

The model depicted adjacent is used for Granovetter’s 1973 paper “The Strength of the Weak Ties” and his theory of social 'weak ties' and interpersonal 'strong ties'. [1]

The conception of a "hydrogen bond" defined as the binding between two atoms as being possible through the medium of a hydrogen ion was first advanced in the unpublished work of American chemist Maurice Huggins in 1919, with his conception of an H-bond, a theory later expanded on by Wendell Latimer and Worth Rodebush in 1920, who cite Huggins in a footnote, in their paper "Polarity and Ionization from the Standpoint of the Lewis Theory of Valence". [7] All three were students of Gilbert Lewis, working in his chemical laboratory of the University of California, Berkeley.

This hydrogen bonding model, as learned by Granovetter in circa 1963, thus became the basis of his first manuscript on the importance of weak social ties in human life. He submitted his paper to the American Sociological Review in 1969, but it was rejected. In 1972, Granovetter submitted a shortened version to the American Journal of Sociology, and it was finally published in May 1973; and by 1986 had became citation classic.

Weak ties | models
The following are Granovetter's original weak tie diagrams:


Granovetter’s fig 1 showing the forbidden triad, depicting person A in a strong bond (AC) with person C, and also in a strong bond (AB) with person B, showing no connection between person C and B, which Granovetter says can never occur, in that a B-C ‘tie’ (weather weak or strong) will always be present. Granovetter's fig 2, parts a and b, showing strong ties (), weak ties ( – – – – – – ), and 'local bridges' between groups.

Hydrogen bonding | Human bonding (model)
The following two diagrams compare the existing weak and strong ties in the attachment between two water molecules, the basic hydrogen bonding model learned by Granovetter in his undergraduate chemistry class, as compared to the weak and strong ties theorized, according to Granovetter, to exist between associative people (human molecules):


Left: Hydrogen bonds (dashed lines) and covalent bonds (straight lines), representing weak and strong ties in water molecule associations. Right: Strong ties, weak ties, and absent ties in an association of ten human molecules. [2]

The following are more recent depictions of Granovetter's weak ties model:


Left: 2007 weak ties / strong ties diagram [3] Middle: 2008 weak ties / strong ties diagram. [4] Right: 2010 weak ties / strong ties diagram. [5]

Education
Granovetter completed his AB in American and modern European history at Princeton in 1965 and PhD in sociology at Harvard in 1970. Granovetter currently is a professor of sociology at Stanford.

See also
● Human chemical bond
● Human bonding

References
1. Granovetter, Mark. (1973). "The Strength of Weak Ties" (cited by 15367), American Journal of Sociology, Vol. 78, Issue 6, May 1973, pp. 1360-1380.
2. (a) Thims, Libb. (2007). Human Chemistry (Volume One) (weak ties, strong ties, pg. 184) . Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two) (weak ties, strong ties, pgs. xiv, 543, 548, 560, 574-78). Morrisville, NC: LuLu.
(c) Interpersonal ties – Wikipedia.
3. Porter, Joshua. (2007). “Weak Ties and Diversity in Social Networks”, Bokardo.com, Oct 05.
4. Milev, Andrew. (2008). “Project Management Software, Mind Mapping, Weak Ties and the Human Brain”, Wrike.com, Jul 28.
5. Robert-Ribes, Jordi. (2010). “The Weak Ties are Stronger”, Jordi.pro, Feb 09.
6. Easley, David and Kleinberg, Jon. (2010). Networks, Crowds, and Markets: Reasoning About a Highly Connected World (ch. 3: Strong and Weak Ties, pgs. 47-84). Cambridge University Press.
7. (a) Evans, Robert C. (1939). An Introduction to Crystal Chemistry (pg. 287). The University Press.
(b) Latimer WM and Rodebush WH. (1920). "Polarity and Ionization from the Standpoint of the Lewis Theory of Valence", J. Am. Chem. Soc., 42: 1419-1433.
(c) Maurice Huggins – Wikipedia.

External links
● Mark Granovetter – Wikipedia.
● Mark Granovetter (faculty) – Stanford University.