Agradecimentos: To the undergraduate and graduate students who followed our courses on Relational Mechanics, Mach’s Principle, Weber’s Electrodynamics and Cosmology, for the many constructive remarks they presented. To our undergraduate and Ph.D. students who are developing researches in these areas. To our friends who are giving us support to continue this work. In special we wish to thank those to whom we gave a first version of this book: C. Roy Keys, Thomas E. Phipps Jr., A. Ghosh, D. Roscoe, A. Martin, R. de A. Martins, M. A. Bueno, W. M. Vieira, M. A. de Faria Rosa, A. Zylbersztajn, D. S. L. Soares, J. I. Cisneros, H. C. Velho, D. Gardelli, J. A. Hernandez and J. E. Lamesa. The suggestions and ideas which we received contributed greatly to the improvement of the book. To the following Publishers and individuals for granting permission to quote from their publications: University of California Press (I. Newton, Mathematical Principles of Natural Philosophy, 1934, Cajori edition); Open Court Publishing Company, a division of Carus Publishing Company, Peru, IL (E. Mach, The Science of Mechanics, 1960, translated by T. J. McCormack); Everyman’s Library, David Campbell Publications Ltd. (G. Berkeley, Philosophical Works - including De Motu and A Treatise Concerning the Principles of Human Knowledge, 1992); Dover Publications (A. Einstein, H. A. Lorentz, H. Weyl and H. Minkowski, The Principle of Relativity, 1952); Cambridge University Press (J. B. Barbour, Absolute or Relative Motion?, 1989); Albert Einstein Archives, The Hebrew University of Jerusalem, Israel (A. Einstein, The Meaning of Relativity, 1980); Dr. Peter Gray Lucas, in name of Dr. H. G. Alexander (The Leibniz-Clarke Correspondence, edited by H. G. Alexander, 1984); Birkhauser Boston and Dr. J. B. Barbour for his translations of E. Schr¨odinger, H. Reissner, A. Einstein, B. and I. Friedlaender (Mach’s Principle - From Newton’s Bucket to Quantum Gravity, edited by J. B. Barbour and H. Pfister, 1995). To the Center for Electromagnetics Research, Northeastern University (Boston, USA), which received us for one year in which we had the first idea to write this book and discussed its contents with some friends. To the Institutes of Physics and Mathematics and to the Center of Logics, Epistemology and History of Sciences of the State University of Campinas - UNICAMP (Brazil), that gave the necessary support to undertake this work. Above all, to my parents, my wife and children for helping me grow as a human being Ver menos