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The Tonti diagram,〔Tonti, E.: The Mathematical Structure of Classical and Relativistic Physics, Birkhäuser (Springer) (2013)〕 created by the Italian physicist and mathematician Enzo Tonti, is a diagram that classifies variables and equations of physical theories of classical and relativistic physics. The theories involved are: ''particle dynamics, analytical mechanics, mechanics of deformable solids, fluid mechanics, electromagnetism, gravitation, heat conduction,'' and ''irreversible thermodynamics''. The classification stems from the observation that each physical variable has a well-defined association with a space and a time element, as shown in Fig. 1, which can be grasped from the corresponding global variable and from its measuring process. == Historical note == The starting point of this classification stems from a remark by Maxwell. Speaking about analogies in different physical theories, Maxwell wrote in 1871:〔Maxwell, J.C.: Remarks on the Mathematical Classification of Physical Quantities. Proc. London Math. Soc. 3 (34), 258-266 (1871) Reprinted by Niven, W.D.: The Scientific Papers of J.C. Maxwell. Dover, New York (1965)〕 Of the factors which compose it (), one is referred to unit of length, and the other to unit of area. This gives what I regard as a very important distinction among vector quantities. This remark leads us to a distinction between vectors referred to lines and vectors referred to surfaces. This is not customarily considered in vector calculus or in physics. In electromagnetism, hence, vectors E and H are associated with lines, and vectors D and B are associated with surfaces. This distinction leads to a classification of physical variables based on their ''association'' with space elements. Maxwell continues: It is only through the progress of science in recent times that we have become acquainted with so large a number of physical quantities that a classification of them is desirable. () But the classification which I now refer to is founded on the mathematical or formal analogy of the different quantities, and not on the matter to which they belong. The classification diagram arises from an analysis of the ''association'' of physical variables in different physical theories, whatever their mathematical nature, i.e. scalars, vectors, tensors, etc., with space and time elements. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tonti diagram」の詳細全文を読む スポンサード リンク
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