Parry Moon
Parry Hiram Moon (/muːn/; February 14, 1898 – March 4, 1988) was an American electrical engineer who, with Domina Eberle Spencer, co-wrote eight scientific books and over 200 papers on subjects including electromagnetic field theory, color harmony, nutrition, aesthetic measure and advanced mathematics. He also developed a theory of holors.[2]
Moon was born in Beaver Dam, Wisconsin, to Ossian C. and Eleanor F. (Parry) Moon. He received a BSEE from University of Wisconsin in 1922 and an MSEE from MIT in 1924. Unfulfilled with his work in transformer design at Westinghouse, Moon obtained a position as research assistant at MIT under Vannevar Bush. He was hospitalized for six months after sustaining injuries from experimental work in the laboratory. He later continued his teaching and research as an associate professor in MIT's Electrical Engineering Department. He married Harriet Tiffany, with whom he had a son. In 1961, after the death of his first wife, he married his co-author, collaborator and former student, Domina Eberle Spencer, a professor of mathematics. They had one son. Moon retired from full-time teaching in the 1960s, but continued his research until his death in 1988.
Moon’s early career focused in optics applications for engineers. Collaborating with Spencer, he began researching electromagnetism and Amperian forces. The quantity of papers that followed culminated in Foundations of Electrodynamics,[3] unique for its physical insights, and two field theory books, which became standard references for many years. Much later, Moon and Spencer unified the approach to collections of data (vectors, tensors, etc.), with a concept they coined "holors".[2] Through their work, they became disillusioned with Albert Einstein's theory of relativityand sought neo-classical explanations for various phenomena.
Moon and Spencer invented the term "holor" (/ˈhoʊlər/; Greek ὅλος "whole") for a mathematical entity that is made up of one or more "independent quantities", or "merates" (/ˈmiːreɪts/; Greek μέρος "part") as they are called in the theory of holors.[2][4][5]With the definitions, properties and examples provided by Moon and Spencer, a holor is equivalent to an array of quantities, and any arbitrary array of quantities is a holor. (A holor with a single merate is equivalent to an array with one element.) The merates or component quantities themselves may be real or complex numbers or more complicated quantities such as matrices. For example, holors include particular representations of:
Note that Moon and Spencer's usage of the term "tensor" may be more precisely interpreted as "tensorial array", and so the subtitle of their work, Theory of Holors: A Generalization of Tensors, may be more precisely interpreted as "a generalization of tensorial arrays". To explain the usefulness of coining this term, Moon and Spencer wrote the following:
Holors could be called "hypernumbers," except that we wish to include the special case of (the scalar), which is certainly not a hypernumber. On the other hand, holors are often called "tensors." But this is incorrect, in general, for the definition of a tensor includes a specific dependence on coordinate transformation. To achieve sufficient generality, therefore, it seems best to coin a new word such as holor.
