1. The first researcher to have considered a particular synchronization different from Einstein's was.H. B. Ives:J. Opt. Soc. Am.,27, 263 (1937). This same synchronization was rediscovered and further discussed byF. R. Tangherlini:Suppl. Nuovo Cimento,20, 1 (1961), who was unaware of the Ives work.
2. The first author to have considered the possibility of different possible synchronizations wasH. Reichenbach:The Philosophy of Space and Time, (Dover, New York, N.Y., 1958), followed byB. Ellis andP. Bowman:Philos. Sci.,34, 116 (1967), byYn. B. Mølchanov:Time in Classical and Relativistic Physics (Zuame, Moscow, 1969). However the complete understanding of the infinite possible synchronizations with a However the complete understanding of the infinite possible synchronizations with a noticeable impact on the world of the relativity experts occurred in 1977 by three important papers byR. Mansouri andR. V. Sexl:Gen. Relativ. Gravit.,8, 497, 515, 809 (1977). Successive developments on this line are due toM. Podlaha:Indian J. Theor. Phys.,26, 189 (1978), toT. S. Sjödin:Nuoco Cimento B,51, 229 (1979) and to ref. (6)G. Cavalleri andG. Spinelli:Phys. Found.,13, 1221 (1983).
3. For example one can use a rod, initially parallel to thex- andx′-axes, give it a velocity parallel to they-axis and synchronize the clocks when the rod crosses the axesx andx′. However one has to decide whether the accelerations along they′-axis of the two ends of the rod are simultaneous for eitherS orS′ or for neither of them.
4. See, for instance,R. Becker:Electromagnetic Fields and Interactions, Electromagnetic Theory and Relativity (P. C. Blaisdell, New York, N.Y., 1964), sect. 74, vol. 1, p. 312;W. H. Panofsky andM. Philipps:Classical Electricity and Magnetism (Addison Wesley, Reading, Mass., 1955), subsect. 14·4, p. 237;C. Møller:The Theory of Relativity (Clarendon press, Oxford, 1972), subsect 1·7, p. 24;M. A. Tonnellat:Les Principes, de la Theorie Electromagnetique et de la Relativité (Masson et Cie., Paris, 1959), subsect. 5·6, p. 106;J. P. Barrat:Electromagnetisme et Relativité Restreinte (Ediscience, Paris, 1972), subsect. 6·4c, pp. 223–224;J. H. Smith:Introduction to Special Relativity (Benjamin Inc., New York, N.Y., 1965), subsect. 2·7, p. 29;J. L. Anderson:Principles of Relativity Physics (Academic Press, New York, N.Y., 1967), subsect. 6·1, p. 134;W. Rindler:Essential Relativity (Van Nostrand Reinbold Company, New York, N.Y., 1969), subsect. 1·3 p. 8;P. C. Biasdell:Electromagnetic Theory and Relativity (New York, N.Y., 1964), sect.74, p. 312;P. G. Bergmann:Introduction to the Theory of Relativity (Prentice-Hall. Inc. Englewood Cliffs, N.J., 1942), Chapter III, especially p. 27.
5. G. Cavalleri, L. Galgani, G. Spavieri andG. Spinelli:Scientia,111, 667 (1976).