(Gringuese) I am a professor of physics at the University of Campinas - UNICAMP,
in Brazil, working with gravitation (Relational Mechanics, Mach's principle and
the origin of inertia, absorption of gravity), electromagnetism (Weber's
Electrodynamics, Ampère's force between current elements, electric field
outside resistive wires carrying steady currents, propagation of electromagnetic signals), cosmology (Hubble's law of redshifts, cosmic background radiation, tired light, infinite universe in space and time) and history of science.
(Russo) ß ÿâëÿþñü ïðåïîäàâàòåëåì ôèçèêè â óíèâåðñèòåòå Êàìïèíàñà - UNICAMP,
â Áðàçèëèè, è èññëåäóþ ãðàâèòàöèþ (ðåëÿòèâèñòñêóþ ìåõàíèêó, ïðèíöèï Ìàõà è ïðîèñõîæäåíèå èíåðöèè,
ïîãëîùåíèå ñèëû ãðàâèòàöèè), ýëåêòðîìàãíåòèçì (ýëåêòðîäèíàìèêó Âåáåðà, ñèëó Àìïåðà ìåæäó ýëåìåíòàìè ñ òîêîì,
ýëåêòðè÷åñêîå ïîëå âíå ïðîâîäîâ, èìåþùèõ ñîïðîòèâëåíèå, íåñóùèõ óñòîé÷èâûé òîê,
ðàñïðîñòðàíåíèå ýëåêòðîìàãíèòíûõ ñèãíàëîâ), êîñìîëîãèþ (çàêîí êðàñíûõ ñìåùåíèé
Õàááëà, êîñìè÷åñêîå ôîíîâîå èçëó÷åíèå, óñòàëîñòü ñâåòà, áåñêîíå÷íîñòü âñåëåííîé
â ïðîñòðàíñòâå è âðåìåíè) è èñòîðèþ íàóêè.
(Portuguese) Sou um professor de física na Universidade Estadual de Campinas - UNICAMP, Brasil, trabalhando com gravitação (Mecânica Relacional), princípio de Mach e origem da inércia, absorção da gravidade), eletromagnetismo (Eletrodinâmica de Weber, força de Ampère entre elementos de corrente, campo elétrico fora de condutores resistivos com corrente constante, propagação de sinais eletromagnéticos), cosmologia (lei de Hubble dos desvios para o vermelho, radiação cósmica de fundo, luz cansada, universo infinito no espaço e no tempo) e história da ciência.
This homepage is not an official publication of the University of Campinas - UNICAMP, his contents have not been examined and/or edited by this institution. The responsibility for its contents belong exclusively with the author.
Esta página não é uma publicação oficial da UNICAMP, seu conteúdo não foi examinado e/ou editado por esta instituição. A responsabilidade por seu conteúdo é exclusivamente do autor.
Papers published by A. K. T. Assis (artigos publicados por A. K. T. Assis)
104. A. K. T. Assis and J. P. M. C. Chaib, Ampère's motor: Its history and the controversies surrounding its working mechanism, Vol. 80, pp. 990-995 (2012). doi: 10.1119/1.4746698. Abstract: In 1822 Ampère created a new kind of motor when he succeeded in spinning a cylindrical magnet around its axis by connecting it to a battery generating a steady current. Nowadays, it is easy to present such a motor in the classroom utilizing a neodymium magnet, a D battery, a steel nail, and a short piece of copper wire. Although it is very simple to observe the rotation, the explanation of this effect is still under dispute. This work presents the history of this motor including the controversy between Ampère and Faraday, as well as the modern explanation based on the field concept. We emphasize the positive outcomes to be gained in the classroom by presenting this device to the students.
102. C. P. Magnaghi and A. K. T. Assis, Calculation of the centre of gravity of the cone utilizing the method of Archimedes, European Journal of Physics, Vol. 33, pp. 637-646 (2012). doi: 10.1088/0143-0807/33/3/637. Abstract: Archimedes calculated the centre of gravity of the cone but the proof of this theorem is not extant in his works. Knorr made a reconstruction of this proof utilizing geometrical arguments. This paper proves this theorem by means of a physical demonstration utilizing the law of the lever, and by adapting from Archimedes the method of mechanical theorems that he described in his letter to Eratosthenes.
101. A. K. T. Assis, Newton and inverse problems, in D. Krause and A. Videira (editors), Brazilian Studies in Philosophy and History of Science: An Account of Recent Works, volume 290 of Boston Studies in the Philosophy of Science, Chapter 3, pp. 71-76 (Springer, Dordrecht, 2011). DOI 10.1007/978-90-481-9422-3_3.
100. A. K. T. Assis, Book review: Alan Hirshfeld, Eureka Man: The Life and Legacy of Archimedes, Science and Education, March (2010). DOI: 10.1007/s11191-010-9244-0. This review was also published in the Newsletter of the International History, Philosophy and Science Teaching Group (March, 2010).
99. A. K. T. Assis, Wilhelm Weber’s works translated into English, 21st Century Science and Technology, Vol. 22, No. 4, pp. 67-69 (2010). Contents: We present a list of the works and letters of Wilhelm E. Weber (1804-1891) which have been translated into English.
98. A. K. T. Assis, M. C. D. Neves and D. S. L. Soares, Hubble’s cosmology: From a finite expanding universe to a static endless universe, in: F. Potter (editor), 2nd Crisis in Cosmology Conference, CCC-2 (Astronomical Society of the Pacific, San Francisco, 2009), pp. 255-267. APS Conference Series, Volume 413. Abstract: We analyze the views of Edwin Hubble (1889-1953) as regards the large scale structure of the universe. In 1929 he initially accepted a finite expanding universe in order to explain the redshifts of distant galaxies. Later on he turned to an infinite stationary universe and a new principle of nature in order to explain the same phenomena. Initially, he was impressed by the agreement of his redshift-distance relation with one of the predictions of de Sitter's cosmological model, namely, the so-called ``de Sitter effect'', the phenomenon of the scattering of material particles, leading to an expanding universe. A number of observational evidences, though, made him highly skeptical with such a scenario. They were better accounted for by an infinite static universe. The evidences he found were: (i) the huge values he was getting for the ``recession'' velocities of the nebulae (1,800 km/s in 1929 up to 42,000 km/s in 1942, leading to v/c = 1/7), with the redshifts interpreted as velocity-shifts. All other known real velocities of large astronomical bodies are much smaller than these. (ii) The ``number effect'' test, which is the running of nebulae luminosity with redshift. Hubble found that a static universe is, within the observational uncertainties, slightly favored. The test is equivalent to the modern ``Tolman effect'', for galaxy surface brightnesses, whose results are still a matter of dispute. (iii) The smallness of the size and the age of the curved expanding universe, implied by the expansion rate that he had determined, and, (iv) the fact that an uniform distribution of galaxies on large scales is more easily obtained from galaxy counts, when a static and flat model is considered. In an expanding and closed universe, Hubble found that homogeneity was only obtained at the cost of a large curvature. We show, by quoting his works, that Hubble remained cautiously against the big bang until the end of his life, contrary to the statements of many modern authors. In order to account for redshifts, in a non-expanding universe, Hubble called for a new principle of nature, like the ``tired-light'' mechanism proposed by Fritz Zwicky in 1929. On the other hand, he was aware of the theoretical difficulties of such a radical assumption. Hubble's approach to cosmology strongly suggests that he would not agree with the present status of the modern cosmological paradigm, since he was, above all, driven by observations and by the consequences derived from them.
97. A. K. T. Assis, J. E. A. Ribeiro and A. Vannucci, The field concepts of Faraday and Maxwell, in: Trends in Physics – Festschrift in Homage to Prof. José Maria Filardo Bassalo (Editora Livraria da Física, São Paulo, 2009), M. S. D. Cattani, L. C. B. Crispino, M. O C. Gomes and A. F. S. Santoro (editors), pp. 31-38. Errata Abstract: We discuss how Faraday (1791-1867) and Maxwell (1831-1879) defined the field concept. According to them magnetic field was a region of space close to magnetized bodies and electric field was a region of space close to electrified bodies.
96. A. K. T. Assis e F. M. d. M. Ravanelli, Consequences of a generalized law of the lever, American Journal of Physics, Vol. 77, pp. 54-58 (2009). DOI: 10.1119/1.2978002. Abstract: We discuss the controversy about the demonstration of the law of the lever as given by Archimedes. One aspect of the discussion concentrates on the meaning of the postulates which he utilized. We analyze what consequences would arise if nature behaved in such a way that the lever followed a generalized power law. In particular, we consider the cases of a torque independent of the distances of the bodies to the fulcrum, proportional to these distances, and quadratic in the distances.
95. W. Weber, Determinations of electrodynamic measure: particularly in respect to the connection of the fundamental laws of electricity with the law of gravitation, 21st Century Science and Technology (59 pages in PDF, posted in November, 2008: http://www.21stcenturysciencetech.com/), English translation by G. Gregory, edited by L. Hecht and A. K. T. Assis. Contents: This is the first complete English translation of W. Weber’s posthmous paper entitled: Elektrodynamische Maassbestimmungen insbesondere über den Zusammenhang des elektrischen Grundgesetzes mit dem Gravitationsgesetze. This work was originally published in W. Weber’s Werke, Vol. IV: Galvanismus und Elektrodynamik, Part 2, edited by H. Weber (Berlin: Julius Springer Verlag, 1894), pp. 479-525.
94. J. A. Hernandes and A. K. T. Assis, Surface charges and fields in stationary conductors with steady currents, in: B. G. Sidharth, F. Honsell, O. Mansutti, K. Sreenivasan and A. De Angelis (editors), Frontiers of Fundamental and Computational Physics (New York, Melville, 2008), pages 236-239. Proceedings of the 9th International Symposium (Udine and Trieste, Italy, 2008). AIP Proceedings, Vol. 1018. Abstract: Is there a force between an external stationary charge and a resistive stationary conductor carrying a steady current? The answer to this question is positive. In this work we present the main results in this interaction. We present experiments published in the literature which measured these effects. We also show the analytical solution for the most common situations, namely: straight wires, strips and toroidal conductors. This force is due to charges spread along the surface of the current carrying conductor. This distribution of surface charges is maintained by the battery, and keep the current flowing along the conductor. This had been pointed out by Kirchhoff and Weber. These surface charges keep the potential gradient along the resistive circuit. They also create an electric field inside and outside the conductor. With this approach we show that there are no fundamental differences between electrostatics and current-carrying conductors.
93. J. A. Hernandes, A. J. Mania, F. R. T. Luna and A. K. T. Assis, The internal and external electric fields for a resistive toroidal conductor carrying a steady poloidal current, Physica Scripta, Vol. 78, 015403 (2008). Abstract: We consider the case of a resistive toroidal conductor carrying a steady current in the poloidal direction. We obtain algebraic expressions for the electric potential, the electric field and the surface charges inside and inside the toroidal shell. We use toroidal coordinates, in which Laplace’s equation is R-separable. We analyze the limiting case of a thin toroid, which can be compared with the solution for the ideal straight solenoid.
92. J. E. A. Ribeiro, A. Vannucci and A. K. T. Assis, The multiple definitions of ‘field’ in the context of Electromagnetism, in: Proceedings of the VI Taller Internacional ENFIQUI 2008 – La Enseñanza de la Física y la Química (Universidad Pedagógica Juan Marinello, Matanzas, Cuba, 8 to 12 July 2008), pp. 1-4, ISBN: 978-959-18-0359-7, M. G. P. Batista (editor). Subject: We discuss the several meanings which have been given to the field concept in the context of electromagnetism.
91. A. K. T. Assis and F. M. M. Ravanelli, Consequences of a quadratic law of the lever, in: M. F. P. d. C. M. Costa, J. B. V. Dorrío, A. C. Pavão and M. Muramatsu (editors), Proceedings of the 5th International Conference on Hands-on Science (Espaço Ciência, Olinda-Recife, 2008), pages 82-84. This paper was also published at: International Journal on Hands-on Science, Vol. 1, pp. 89-91 (2008). Abstract: We present the discussion which exists in the literature related to Archimedes’s demonstration of the law of the lever. One important aspect of the argument concentrates on the meaning of his postulates. In order to clarify this whole subject, we analyze what consequences would arise if nature followed a different law of the lever. We concentrate, in particular, in the case of a torque proportional to the square of the distances of the bodies to the fulcrum. We consider not only a linear lever but also a horizontal triangle which can rotate around a horizontal axis parallel to one of its sides.
90. W. Weber, Determinations of electrodynamic measure: concerning a universal law of electrical action, 21st Century Science and Technology (146 pages in PDF, posted in March, 2007: http://www.21stcenturysciencetech.com/), English translation by S. P. Johnson, edited by L. Hecht and A. K. T. Assis. Contents: This is the first complete English translation of W. Weber’s paper of 1846 entitled: Elektrodynamische Maassbestimmungen: Ueber ein allgemeines Grundgesetz der elektrischen Wirkung. This work was originally published at the Abhandlungen bei Begründung der Königl. Sächs. Gesellschaft der Wissenschaften am Tage der zweihundertjährigen Geburtstagfeier Leibnizen’s herausgegeben von der Fürstl. Jablonowskischen Gesellschaft (Leipzig), pp. 211-378 (1846). Reprinted in W. Weber’s Werke, Vol. III: Galvanismus und Elektrodynamik, Part 1, edited by H. Weber (Berlin: Julius Springer Verlag, 1893), pp. 25-214. In this paper Weber presented his force depending on the relative velocity and relative acceleration between the interacting charges. It was based upon Coulomb’s force between point charges, Ampère’s force between current elements and Faraday’s law of induction. In this paper Weber also presented an experimental proof of Ampère’s force.
89. A. K. T. Assis, Gravitation and cogravitation, Annales de la Fondation Louis de Broglie, Vol. 32, pp. 117-120 (2007). Abstract: Review of the book Gravitation and Cogravitation: Developing Newton’s Theory of Gravitation to Its Physical and Mathematical Conclusion, by Oleg D. Jefimenko.
88. A. K. T. Assis, M. P. Souza Filho, J. J. Caluzi and J. P. M. C. Chaib, From electromagnetism to electrodynamics: Ampère’s demonstration of the interaction between current carrying wires, Proceedings of the 4th International Conference on Hands-on Science (University of Azores, Ponta Delgada, Portugal, 2007), pp. 9-16, M. F. P. d. C. M. Costa, J. B. V. Dorrio and R. Reis (editors). Abstract: We present Oersted’s discovery of the torque exerted by a current carrying wire upon a nearby magnet and his interpretation of this experiment. This opened the field of electromagnetism, describing the interaction between current carrying wires and magnets. We discuss Ampère’s alternative interpretation and his experiment showing a force between a magnet and a current carrying spiral. This led him to try an interaction between two current carrying spirals, without any magnet. He was successful with this trial and this is one of the most important experiments in the history of electricity. This led him to the result that current carrying parallel wires attract (repel) one another when the currents flow along the same direction (in opposite directions). This new field of research describing the interaction between current carrying wires was called electrodynamics by Ampère. We show how to perform Ampère’s crucial experiment with simple and cheap materials.
87. A. K. T. Assis and J. A. Hernandes, Magnetic energy and effective inertial mass of the conduction electrons in circuit theory, Electromagnetic Phenomena, Vol. 6, pp. 29-35 (2006). Abstract: In this work we calculate the electrodynamic energy of conductors carrying slowly time-varying currents. We show that this energy can be quantitatively identified with the classical kinetic energy of the current-carrying electrons with effective inertial mass proportional to the self-inductance of the conductor.
86. J. A. Hernandes and A. K. T. Assis, Electric potential due to an infinite conducting cylinder with internal or external point charge, Journal of Electrostatics, Vol. 63, pp. 1115-1131 (2005). Abstract: We utilize the Green’s function method in order to calculate the electric potential due to an infinite conducting cylinder held at zero potential and a point charge inside and outside it. We calculate and plot the net force upon the point charge as a function of its distance to the axis of the cylinder. We show that this force goes to zero when the radius of the cylinder goes to zero, no matter the distance of the external point charge to the conducting line.
85. J. A. Hernandes, E. Capelas de Oliveira and A. K. T. Assis, Resistive plates carrying a steady current: electric potential and surface charges close to the battery, Foundations of Physics Letters, Vol. 18, pp. 275-289 (2005). Abstract: We treat the problem of two resistive plates carrying a steady current in the same direction. We consider a linear battery orthogonal to the direction of the current in the middle of the plates. We study the behavior of the surface charges close to the battery. We also consider the case of a single resistive plate carrying a steady current.
84. J. A. Hernandes and A. K. T. Assis, The electric field outside and inside a resistive spherical shell carrying a steady azimuthal current, Physica Scripta, Vol. 72, pp. 212-217 (2005). Abstract: We calculate the potential, electric field and surface charges outside and inside a resistive spherical shell carrying a steady azimuthal current. We obtain a time-independent electric field different from zero in both regions.
83. A. K. T. Assis and J. A. Hernandes, Telegraphy equation from Weber’s electrodynamics, IEEE Transactions on Circuits and Systems II, Vol. 52, pp. 289-292 (2005), Abstract: We derive the telegraphy equation according to Weber’s electrodynamics for signal propagating along a very long bidimensional wire in the shape of a rectangular strip of zero thickness. We also derive this equation of a twin lead composed of two of these parallel very long bidimensional wires facing each other. We compare this result with classical electromagnetism.
82. A. K. T. Assis, Weber’s electrodynamics and Mach’s principle in the 21st century, in: Vom Magnetismus zur Elektrodynamik, G. Wolfschmidt (editor), (Schwerpunkt Geschichte der Naturwissenschaften, Mathematik und Technik; Hamburg, 2005), pp. 10-11. Contents: We list some of the main topics related to Weber’s electrodynamics and Mach’s principle which are being researched nowadays.
81. R. S. Mendes, L. C. Malacarne and A. K. T. Assis, Virial theorem for Weber’s law, in: Has the Last Word Been Said on Classical Electrodynamics? New Horizons; A. Chubykalo, A. Espinoza, V. Onoochin and R. Smirnov-Rueda (editors), (Rinton Press, Paramus, 2004), pp. 67-70. Abstract: We derive the virial theorem for Weber’s law applied to gravitation and electromagnetism.
79. J. A. Hernandes and A. K. T. Assis, Surface charges and external electric field in a toroid carrying a steady current, Brazilian Journal of Physics, Vol. 34, pp. 1738-1744 (2004). Abstract: We solve the problem of a resistive toroid carrying a steady azimuthal current. We use standard toroidal coordinates, in which case Laplace’s equation is R-separable. We obtain the electric potential inside and outside the toroid, in two separate cases: 1) the toroid is solid; 2) the toroid is hollow (a toroidal shell). Considering these two cases, there is a difference in the potential inside the hollow and solid toroids. We also present the electric field and the surface charge distribution in the conductor due to this steady current. These surface charges generate not only the electric field that maintains the current flowing, but generate also the electric field outside the conductor. The problem of a toroid is interesting because it is a problem with finite geometry, with the whole system (including the battery) contained within a finite region of space. The problem is solved in an exact analytical form. We compare our theoretical results with an experimental figure demonstrating the existence of the electric field outside the conductor carrying steady current.
78. A. K. T. Assis, The principle of physical proportions, Annales de la Fondation Louis de Broglie, Vol. 29, pp. 149-171 (2004). Abstract: We propose the principle of physical proportions, according to which all laws of physics can depend only on the ratio of known quantities of the same type. An alternative formulation is that no dimensional constants should appear in the laws of physics; or that all constants of physics (like the universal constant of gravitation, light velocity in vacuum, Planck’s constant, Boltzmann’s constant etc.) must depend on cosmological or microscopic properties of the universe. With this generalization of Mach’s principle we advocate doing away with all absolute quantities in physics. We present examples of laws satisfying this principle and of others which do not. These last examples suggest that the connected theories leading to these laws must be incomplete. We present applications of this principle in some fundamental equations of physics.
76. A. K. T. Assis and K. H. Wiederkehr, Weber quoting Maxwell, Mitteilungen der Gauss-Gesellschaft, Vol. 40, pp. 53-74 (2003). Abstract: This article deals with the supersession of Wilhelm Weber’s and Franz Neumann’s older theory of electrodynamics by Maxwell’s theory in the last third of the 19th century. Starting-point and basis for the presentation are the few quotations that can be found in Weber’s works. The discussion was mainly performed by Carl von Neumann and Johann Karl Friedrich Zöllner. Both were engaged supporters and advocates of Weber’s view of electricity. Points of controversy were: (1) The theory of close-range effects, which is identical to Maxwell’s concept of field and which stood in contrast to distant range theory (prototype: Newton’s gravitational law), and (2) the assumption of the existence of an electrical substance. Weber persisted right to the end in his concept and developed an atomic model that can be regarded as an initial stage of the Rutherford-Bohr atomic model. Consensus existed in the absolute electrical measurement systems. J. Cl. Maxwell inferred the velocity of light from the Kohlrausch-Weber-experiment. Weber’s absolute electro-magnetic system served as a basis for the international units of measure in 1881.
75. J. A. Hernandes and A. K. T. Assis, Electric potential for a resistive toroidal conductor carrying a steady azimuthal current, Physical Review E, Vol. 68, 046611 (2003). Abstract: In this work we treat a resistive toroidal conductor carrying a steady azimuthal current. We calculate the electric potential everywhere in space. We also present the electric field inside and outside the toroid and the surface charges distribution along the conductor. We compare our theoretical result with Jefimenko’s experiment.
74. J. Fukai and A. K. T. Assis, Testing Mach’s principle in electrodynamics, Canadian Journal of Physics, Vol. 81, pp. 1239-1242 (2003). Abstract: We analyze the consequences of Mach’s principle as applied to electromagnetism. This view reveals new effects not predicted by standard electromagnetic theory.
73. J. A. Hernades and A. K. T. Assis, The potential, electric field and surface charges for a resistive long straight strip carrying a steady current, American Journal of Physics, Vol. 71, pp. 938-942 (2003). Abstract: We consider a long resistive straight strip carrying a constant current and calculate the potential and electric field everywhere in space and the density of surface charges along the strip. We compare these calculations with experimental results.
72. A. K. T. Assis, On the first electromagnetic measurement of the velocity of light by Wilhelm Weber and Rudolf Kohlrausch, in Volta and the History of Electricity, edited by F. Bevilacqua and E. A. Giannetto (Università degli Studi di Pavia and Editore Ulrico Hoepli, Milano, 2003), pp. 267-286. Abstract: The electrostatic, electrodynamic and electromagnetic systems of units utilized during last century by Ampère, Gauss, Weber, Maxwell and all the others are analyzed. It is shown how the constant c was introduced in physics by Weber’s force of 1846. It is shown that it has the unit of velocity and is the ratio of the electromagnetic and electrostatic units of charge. Weber and Kohlrausch’s experiment of 1855 to determine c is quoted, emphasizing that they were the first to measure this quantity and obtained the same value as that of light velocity in vacuum. It is shown how Kirchhoff in 1857 and Weber (1857-64) independently of one another obtained the fact that an electromagnetic signal propagates at light velocity along a thin wire of negligible resistivity. They obtained the telegraphy equation utilizing Weber’s action at a distance force. This was accomplished before the development of Maxwell’s electromagnetic theory of light and before Heaviside’s work. As an Appendix of this paper there is a complete English translation of the paper by W. Weber and R. Kohlrausch, Ueber die Elektricitätsmenge, welche bei galvanischen Strömen durch den Querschnitt der Kette fliesst, Annalen der Physik, Vol. 99, pp. 10-25 (1856): W. Weber and R. Kohlrausch, On the amount of electricity which flows through the cross-section of the circuit in galvanic currents, translated by S. P. Johnson and edited by L. Hecht, in Volta and the History of Electricity, edited by F. Bevilacqua and E. A. Giannetto (Università degli Studi di Pavia and Editore Ulrico Hoepli, Milano, 2003), pp. 287-297.
71. A. K. T. Assis and J. Guala-Valverde, Frequency in relational mechanics, Annales de la Fondation Louis de Broglie, Vol. 28, pp. 83-97 (2003). Abstract: We analyze the dependence of the frequency of oscillation of several macroscopic motions as regards the density of distant gravitational matter according to relational mechanics. We conclude that in most situations the frequency is inversely proportional to the square root of this density.
70. A. K. T. Assis, The relationship between Mach's principle and the principle of physical proportions, in: Mach's Principle and the Origin of Inertia, M. Sachs and A. R. Roy (Editors), (Apeiron, Montreal, 2003), pp. 37-44. Abstract: Mach's principle is compared with the principle of physical proportions. Laws that are compatible and others not compatible with the latter principle are discussed. Avenues for the implementation of this principle are also outlined.
69. A. K. T. Assis, K. Reich and K. H. Wiederkehr, Gauss and Weber's creation of the absolute system of units in physics, 21st Century Science and Technology, Vol. 15, No. 3, pp. 40-48 (2002). Contents: It is presented the absolute system of units created by Gauss and Weber. It is discussed Gauss's seminal paper of 1832, the intensity of the earth's magnetic force reduced to absolute measurement, and his solution of this problem. The joint work of Gauss and Weber is analyzed and also their creation of the magnetic association.
68. A. K. T. Assis and J. Guala-Valverde, On absolute and relative motions in physics, Journal of New Energy, Vol. 6, No. 4, pp. 8-12 (2002). Abstract: The authors present the Newtonian definitions of absolute and relative motion. The idea is defended that only relative motions of matter relative to matter can be detect and lead to measurable effects. Phenomena is analyzed depending on velocity and acceleration in electromagnetism and mechanics.
67. A. K. T. Assis and J. A. Hernandes, Electric potential for a toroidal ring carrying a constant current, Proceedings of the XXIII Encontro Nacional de Física de Partículas e Campos (15 to 19/10/2002, Águas de Lindóia, Brazil), P-115. Abstract: In this work we treat a conducting toroidal ring carrying a constant current. We calculate the electric potential everywhere in space. We compare our theoretical result with Jefimenko's experiment.
66. J. A. Hernandes and A. K. T. Assis, Potential, electric field and surface charges for a resistive long straight strip carrying a constant current, Proceedings of the XXIII Encontro Nacional de Física de Partículas e Campos (15 to 19/10/2002, Águas de Lindóia, Brazil), P-163. Abstract: We consider a long resistive straight strip carrying a constant current. We calculate the potential and electric field everywhere in space and also the density of surface charges along the strip. We compare the calculations with experimental results.
65. A. K. T. Assis, On the unification of forces of nature, Annales de la Fondation Louis de Broglie, Vol. 27, pp. 149-161 (2002). Abstract: Different aspects of physical interaction are considered: inertia, gravitation, electrostatics, magnetostatics and galvanism. It is discussed the experimental and theoretical reasons leading to the unification of some of them. It is then explored by analogies what might lead to the unification of gravitation with electromagnetism.
64. H. Torres S. and A. K. T. Assis, The influence of the electric field outside a resistive solenoid on the Aharonov-Bohm effect, Revista de la Facultad de Ingenieria de la Universidad de Tarapaca (Chile), Vol. 9, pp. 29-34 (2001). Abstract: It is a known fact that there is no magnetic field outside an infinite solenoid carrying a constant current, although there is a magnetic vector potential non-null outside it. The existence of the Aharonov-Bohm effect (AB) is usually considered as a proof of the relevance of the vector potential for quantum mechanics. In this paper we will see that there is a non null electric field outside an infinite solenoid carrying a constant current and its possible relevance to the analysis of the Aharonov-Bohm effect. When calculating, we introduce the Galilean invariance of Maxwell's equations and then we obtain the contribution to the AB effect due to electric potential.
63. A. K. T. Assis, J. A. Hernandes and J. E. Lamesa, Surface charges in conductor plates carrying constant currents, Foundations of Physics, Vol. 31, pp. 1501-1511 (2001). Abstract: In this work we analyze the case of resistive conductor plates carrying constant currents, utilizing surface charge distributions. We obtain the electric potential in the plates and in the space surrounding them. We obtain a non-vanishing electric field outside the conductors. We compare the theoretical results with experimental data present in the literature.
62. A. K. T. Assis, Applications of the principle of physical proportions to gravitation, in: Gravitation, Electromagnetism and Cosmology - Toward a New Synthesis, K. Rudnicki (editor), (Apeiron, Montreal, 2001), pp. 1-7. Abstract: We propose the principle of physical proportions, according to which all laws of physics may depend only on the ratio of quantities of the same type. We present examples of laws that satisfy this principle, and others that do not. These examples suggest that the theories leading to these laws must be incomplete.
61. A. K. T. Assis and A. Zylbersztajn, The influence of Ernst Mach in the teaching of mechanics, Science and Education, Vol. 10, pp. 137-144 (2001). Abstract: We present Newton's main ideas for the formulation of classical mechanics as given in the Principia. Then we discuss Ernst Mach's criticisms of Newtonian mechanics as contained in his book The Science of Mechanics. We analyze the influence of Mach's ideas in the teaching of classical mechanics considering five representative textbooks: those of Kittel, Knight and Ruderman; Marion and Thornton; Symon; Feynman, Leighton and Sands; and Goldstein. We conclude that the influence of Mach's ideas has been very great, being incorporated in the textbooks, although not always with the deserved acknowledgment.
59. A. K. T. Assis, J. Fukai and H. B. Carvalho, Weberian induction, Physics Letters A, Vol. 268, pp. 274-278 (2000). Abstract: Various kinds of electric polarization of a rotating metallic disc are discussed. A new kind of induction is predicted by Weber's electrodynamics, but not by Maxwellian electrodynamics. An experiment test to check this new effect is proposed.
58. A. K. T. Assis and J. I. Cisneros, Surface charges and fields in a resistive coaxial cable carrying a constant current, IEEE Transactions on Circuits and Systems I, Vol. 47, pp. 63-66 (2000), Abstract: We calculate the surface charges, potentials, and fields in a long cylindrical coaxial cable with inner and outer conductors of finite conductivities and finite areas carrying a constant current. It is shown that there is an electric field outside the return conductor.
56. A. K. T. Assis, The meaning of the constant c in Weber's electrodynamics, in: Proceeding of the International Conference Galileo Back in Italy II, R. Monti (editor), (Societá Editrice Andromeda, Bologna, 2000), pp. 23-36. Abstract: In this work it is analysed three basic electromagnetic systems of units utilized during last century by Ampère, Gauss, Weber, Maxwell and all the others: The electrostatic, electrodynamic and electromagnetic ones. It is presented how the basic equations of electromagnetism are written in these systems (and also in the present day international system of units MKSA). Then it is shown how the constant c was introduced in physics by Weber's force. It is shown that it has the unit of a velocity and is the ratio of electromagnetic and electrostatit units of charge. Weber and Kohlrausch's experiment to determine c is presented, emphasizing that they were the first to measure this quantity and obtained the same value as that of light velocity in vacuum. It is shown how Kirchhoff and Weber obtained independently of one another, both working in the framework of Weber's electrodynamics, the fact that an electromagnetic signal (of current or potential) propagate at light velocity along a thin wire of negligible resistivity.
55. A. K. T. Assis and H. Torres Silva, Comparison between Weber's electrodynamics and classical electrodynamics, Pramana Journal of Physics, Vol. 55, pp. 393-404 (2000). Abstract: We present the main aspects of Weber's electrodynamics and of Maxwell's equations. We discuss Maxwell's point of view related to Weber's electrodynamics. We compare Weber's force with Lorentz's force. We analyse the relation between Weber's law and Maxwell's equation. Finally, we discuss some experiments performed and proposed with which we can distinguish Weber's force from Lorentz's one.
54. A. K. T. Assis and J. Guala-Valverde, Mass in relational mechanics, Apeiron, Vol. 7, pp. 131-132 (2000). Abstract: We clarify a misunderstanding that appeared in the literature.
53. A. K. T. Assis and Marcelo Bueno, Bootstrap effect in classical electrodynamics, Revista Facultad de Ingenieria de la Universidad de Tarapaca (Chile), Vol. 7, pp. 49-55 (2000). Abstract: We calculate the force on part of a circuit due to the remaining circuit using Ampère's force and Grassmann's force. Using a symmetrical configuration we perform the calculations using linear current elements. We show that both expressions give the same result. Then we present some general arguments to show that even with Grassmann's force a single closed circuit of arbitrary form cannot exert a net force on itself. Moreover, we show that the force acting on any straight conductor belonging to a closed circuit of arbitrary form, due to the remaining of this circuit, is orthogonal to this conductor and has the same value according to Ampère's force and to Grassmann's force.
52. A. K. T. Assis, W. A. Rodrigues Jr. and A. J. Mania, The electric field outside a stationary resistive wire carrying a constant current, Foundations of Physics, Vol. 29, pp. 729-753 (1999). Abstract: We present the opinion of some authors who believe there is no force between a stationary charge and a stationary resistive wire carrying a constant current. We show that this force is different from zero and present its main components: the force due to the charges induced in the wire by the test charge and a force proportional to the current in the resistive wire. We also discuss briefly a component of the force proportional to the square of the current which should exist according to some models and another component due to the acceleration of the conduction electrons in a curved wire carrying a dc current (centripetal acceleration). Finally, we analyse experiments showing the existence of the electric field proportional to the current in resistive wires.
51. A. K. T. Assis, Arguments in favour of action at a distance, in: Instantaneous Action at a Distance - Pro and Contra, edited by A. E. Chubykalo, V. Pope and R. Smirnov-Rueda (Nova Science Publishers, Commack, 1999), pp. 45-56. Abstract: Several arguments favouring instantaneous action at a distance are presented. The action at a distance laws of Newton, Coulomb, Ampère and Weber are analysed. Historical evidence that Weber's electrodynamics led to the propagation of electromagnetic signals with finite velocity prior to the development of Maxwell's equations are emphasized. The implementation of Mach's principle with Weber's law applied to gravitation is discussed.
50. A. K. T. Assis and J. J. Caluzi, Charged particle oscillating near a capacitor, Galilean Electrodynamics, Vol. 10, pp. 103-106 (1999). Abstract: We study the oscillation of a charged particle near a capacitor in four different models: Classical mechanics, Weber's electrodynamics plus classical mechanics, relativistic mechanics, and Weber's electrodynamics plus the mechanics of Erwin Schrodinger. We show that only the third and fourth models yield a physically reasonable results.
49. A. K. T. Assis and A. J. Mania, Surface charges and electric field in a two-wire resistive transmission line, Revista Brasileira de Ensino de Física, Vol. 21, pp. 469-475 (1999). Abstract: We consider a two-wire resistive transmission line carrying a constant current. We calculate the potential and electric field outside the wires showing that they are different from zero even for stationary wires carrying dc currents. We also calculate the surface charges giving rise to these fields and compare the magnetic force between the wires with the electric force between them. Finally we compare our calculations with Jefimenko's experiment.
48. A. K. T. Assis and J. I. Cisneros, The problem of surface charges and fields in coaxial cables and its importance for relativistic physics, in: Open Questions in Relativistic Physics, F. Selleri (editor), (Apeiron, Montreal, 1998), pp. 177-185. Abstract: We calculate the surface charges, potentials and fields in a long cylindrical coaxial cable with inner and outer conductors of finite conductivities and finite areas. It is shown that there is an electric field outside the return conductor.
47. M. A. Bueno and A. K. T. Assis, Deriving force from inductance, IEEE Transactions on Magnetics, Vol. 34, pp. 317-319 (1998). Abstract: The correctness of calculating the force on current carrying circuits by taking the derivative of the inductance coefficient of the circuits is shown even in the case of a single closed circuit, contrary to the opinion of some authors. This demonstration is illustrated with the force exerted by a cylinder with poloidal current on an infinitesimal strip belonging to the same cylinder. The force is calculated directly from the force expressions and also by differentiating the self-inductance of the cylinder. This result is another proof of the equivalence between Ampère and Grassmann's forces.
46. Marcelo Bueno and A. K. T. Assis, Equivalence between the formulas for inductance calculation, Canadian Journal of Physics, Vol. 75, pp. 357-362 (1997). Abstract: We demonstrate the equivalence for the self-inductance of closed circuits, with the formulas of Neumann, Weber, Maxwell, and Graneau.
45. J. J. Caluzi and A. K. T. Assis, A critical analysis of Helmholtz’s argument against Weber’s electrodynamics, Foundations of Physics, Vol. 27, pp. 1445-1452 (1997). Abstract: We present Helmholtz's argument against Weber's electrodynamics. It is related with a fixed charged nonconducting spherical shell and a charged particle moving inside it. Then we utilize Weber's electrodynamics plus Schrödinger's expression for gravitational interactions in order to obtain the equation of motion and to study this situation. We show that this approach avoids the problems pointed out by Helmholtz. Moreover, it indicates that the effective inertial mass of the charged particle will depend not only on the electrostatic potential of the shell but also on its velocity. This is a relevant aspect of Weber's theory.
44. Marcelo Bueno and A. K. T. Assis, Self-inductance of solenoids, bi-dimensional rings and coaxial cables, Helvetica Physica Acta, Vol. 70, pp. 813-821 (1997). Abstract: We compare the self-inductance formulae of Neumann, Weber, Maxwell and Graneau. To this end we present exact and algebraic formulae for the self-inductance of solenoids, bi-dimensional rings and coaxial cables. We show that these four formulas agree exactly with one another for closed circuits.
43. Marcelo Bueno and A. K. T. Assis, Proof of the identity between Ampère and Grassmann’s forces, Physica Scripta, Vol. 56, pp. 554-559 (1997). Abstract: We consider a poloidal current flowing over the surface of a conducting cylinder of length l and radius a. We calculate exactly the force on a surface current element belonging to this cylinder due to the remainder of the circuit with Ampère and Grassmann's expressions. We conclude that the formulae agree with one another for any value of l/a. We then generalize this result for any current element belonging to a closed surface or volumetric currents of arbitrary forms.
42. A. K. T. Assis, Circuit theory in Weber electrodynamics, European Journal of Physics, Vol. 18, pp. 241-246 (1997). Abstract: We present a derivation of the equation describing the current flow in a circuit with self-inductance based on Newton's second law plus the Weber force or, alternatively, plus the Lorentz or Liénard-Schwarzschild force. In Weber's approach the self-inductance can be treated as a measure of the effective average inertial mass of the conduction electrons.
41. A. K. T. Assis and Marcelo A. Bueno, Equivalence between Ampère and Grassmann's forces, IEEE Transactions on Magnetics, Vol. 32, pp. 431-436 (1996). Abstract: We calculate the force on part of a single closed circuit due to the remaining circuit in four different geometries according to the forces of Ampère and Grassmann. All analytical calculations are performed using surface or volume current elements in order to avoid the divergences which appear with linear current elements of zero diameter. We conclude that when we consider the action of a closed circuit as a whole and utilize only circuits with closed lines of current, there will be an equivalence between the expressions of Grassmann and Ampère. This means that both of them are compatible with the experimental findings related to Ampère's bridge, contrary to the opinion of some authors.
40. J. J. Caluzi and A. K. T. Assis, The oscillatory motion of charged particles by Weber’s electrodynamics, in: New Frontiers in Physics, Vol. I, T. P. Gill (ed.), (Hadronic Press, Palm Harbor, 1996), pp. 129-143. Abstract: We analyse the oscillatory motion of a charged particle outside an ideal capacitor by four different models: classical, relativistic, Weber's electrodynamics and Weber's electrodynamics plus Schrödinger's mechanics. These two last models yield a period of oscillation depending on the voltage of the capacitor.
39. A. K. T. Assis and P. Graneau, Nonlocal forces of inertia in cosmology, Foundations of Physics, Vol. 26, pp. 271-283 (1996). Abstract: This paper reviews the origin of inertia according to Mach's principle and Weber's law of gravitation. The resulting theory is based on simultaneous nonlocal gravitational interactions between particles in the solar system and others in the remote universe beyond the Milky Way galaxy. It explains the precession of the perihelion of Mercury. A most important implication of the Mach-Weber theory of the force of inertia is the necessity of a large amount of uniformly distributed matter in the galactic universe. This matter could be the source of the cosmic background radiation. Nonlocal inertia forces are compatible with a static universe and also with an expanding universe but the latter would demand slow changes in the mass of particles and the gravitational constant.
38. A. K. T. Assis and Marcelo Bueno, Longitudinal forces in Weber's electrodynamics, International Journal of Modern Physics B, Vol. 9, pp. 3689-3696 (1995). Abstract: We analyze the existence of longitudinal forces with Weber's electrodynamics. We show that they exist. But they cannot explain the exploding wire phenomena due to their order of magnitude.
37. J. J. Caluzi and A. K. T. Assis, An analysis of Phipps's potential energy, Journal of the Franklin Institute, Vol. 332B, pp. 747-753 (1995). Abstract: We discuss a modification of Weber's law proposed by T. E. Phipps. We calculate the energy and force on a charge moving inside and outside a capacitor according to Phipp's modification of Weber's electrodynamics. When Phipps postulated his potential energy he answered Helmholtz's criticism of Weber's law (the negative mass behaviour). But when we utilize Phipps's potential energy together with the classical kinetic energy this leads to an unphysical result.
36. A. K. T. Assis, Gravitation as a fourth order electromagnetic effect, in: Advanced Electromagnetism: Foundations, Theory and Applications, T. W. Barrett and D. M. Grimes (eds.), (World Scientific, Singapore, 1995), pp. 314-331. Abstract: We present a generalized Weber's law for electromagnetism including terms of fourth and higher orders in 1/c. These extra terms when applied to the force between two neutral dipoles yield an equivalent to Newton's law of universal gravitation as a fourth order electromagnetic effect.
35. Marcelo A. Bueno and A. K. T. Assis, A new method for inductance calculations, Journal of Physics D, Vol. 28, pp. 1802-1806 (1995). Abstract: A new method for calculating inductances is presented. The method results in analytically simple expressions that replace the traditional tables and working formulae. Moreover, it overcomes the diverging self-inductances of thin wires.
34. M. C. D. Neves and A. K. T. Assis, The Compton effect as an explanation for the cosmological redshift, Quarterly Journal of the Royal Astronomical Society, Vol. 36, pp. 279-280 (1995). Subject: We discuss if the Compton effect is or not a reasonable explanation for the cosmological redshift yielding Hubble's law.
33. A. K. T. Assis, Weber's force versus Lorentz's force, Physics Essays, Vol. 8, pp. 335-341 (1995). Abstract: We make a comparison between Weber's force and Lorentz's force. First, we present the historical appearance of these two forces. Then we show their theoretical and conceptual differences. After this we discuss some different predictions of experiments with these two expressions showing how they can be distinguished in the laboratory.
32. A. K. T. Assis and M. C. D. Neves, The redshift revisited, Astrophysics and Space Science, Vol. 227, pp. 13-24 (1995). This paper was also published in: Plasma Astrophysics and Cosmology, A. L. Peratt (ed.), (Kluwer Academic Publishers, Dordrecht, 1995), pp. 13-24. Abstract: We analyse the history of modern comsmology based on the redshift phenomenon and on the cosmic background radiation (CBR). We show the models of different authors for the interpretation of the redshift and how the tired light models predicted the correct value of 2.7K temperature previous to Gamow and collaborators.
31. A. K. T. Assis, Weber's law and Mach's principle, in: Mach's Principle: From Newton's Bucket to Quantum Gravity, H. Pfister and J. B. Barbour (eds.), (Birkhäuser, Boston, 1995), pp. 159-171. Subject: We discuss the implementation of Mach's principle based on Weber's law applied to gravitation.
29. A. K. T. Assis and P. Graneau, The reality of Newtonian forces of inertia, Hadronic Journal, Vol. 18, pp. 271-289 (1995). Abstract: We present a historical analysis of the inertial forces and of the theories developed to explain the origin of inertia. Then we introduce the principle of dynamical equilibrium and its relevance to mechanics. We analyse the Mach-Weber model which implements Mach's principle with Newtonian simultaneous interactions and we argue for the reality of the inertial forces, that is: the force of free fall (-ma), the centrifugal force and the Coriolis force. Lastly we present an experimental consequence of the Mach-Weber model which differs from Newton's law of gravitation.
28. A. K. T. Assis and M. C. D. Neves, History of the 2.7 K temperature prior to Penzias and Wilson, Apeiron, Vol. 2, pp. 79-84 (1995). Abstract: We present the history of estimates of the temperature of intergalactic space. We begin with the works of Guillaume and Eddington on the temperature of interstellar space due to starlight belonging to our Milky Way galaxy. Then we discuss works relating to cosmic radiation, concentrating on Regener and Nernst. We also discuss Finlay-Freunlich's and Max Born's important research on this topic. Finally, we present the work of Gamow and collaborators. We show that the models based on a universe in dynamical equilibrium without expansion predicted the 2.7K temperature prior to and better than the models based on the big bang. There are two Appendices to this paper. One is a complete English translation of E. Regener, Der Energiestrom der Ultrastrahlung, Zeitschrift für Physik, Vol. 80, pp. 666-669 (1933): E. Regener, The energy flux of cosmic rays, Apeiron, Vol. 2, pp. 85-86 (1995), translation by G. Moesle. The second Appendix is a complete English translation of W. Nernst, Die Strahlungstemperatur des Universums, Annalen der Physik, Vol. 32, pp. 44-48 (1938): W. Nernst, The radiation temperature of the universe, Apeiron, Vol. 2, pp. 86-87 (1995), translation by G. Moesle.
27. J. J. Caluzi and A. K. T. Assis, Schrödinger's potential energy and Weber's electrodynamics, General Relativity and Gravitation, Vol. 27, pp. 429-437 (1995). Abstract: We discuss Schrödinger's approach to gravitational interactions and Weber's electrodynamics. Then we make use of this model to calculate the energy of a charge moving inside and outside an ideal capacitor. This results in an ultimate speed, c, and in the variation of the mass of the particle with the electrostatic potential and its velocity.
26. P. Graneau and A. K. T. Assis, Kirchhoff on the motion of electricity in conductors, Apeiron, Vol. 19, pp. 19-25 (1994). Abstract: We comment on and translate Gustav Kirchhoff's important paper of 1857 entitled On the motion of electricity in conductors. The significance of this paper is that Kirchhoff proved with action at a distance that electric disturbances travel along wires of negligible resistance with the velocity of light. He accomplished this with the laws of Newtonian electrodynamics (Coulomb, Ampere, F. Neumann and Weber) before Maxwell had formulated his equations.
25. A. K. T. Assis and D. S. Thober, Unipolar induction and Weber's electrodynamics, in: Frontiers of Fundamental Physics, M. Barone and F. Selleri (eds.), (Plenum Press, New York, 1994), pp. 409-414. Subject: We discuss unipolar induction and how it can be interpreted based on Weber's electrodynamics. We present predictions of the results of new experiments based on Weber's law.
24. A. K. T. Assis and R. A. Clemente, The influence of temperature on gravitation, Nuovo Cimento B, Vol. 108, pp. 713-716 (1993). Abstract: We present some general reasonings using the mass-energy equivalence and Weber's force law for gravitation to show that the weight of a body should increase with its temperature. The two approaches predict a fractional change of weight or, equivalently, of the gravitational constant G, of one part in 10^{14} per degree.
23. A. K. T. Assis, Compliance of a Weber's force law for gravitation with Mach's principle, in: Space and Time Problems in Modern Natural Sciences, Part II, P. N. Kropotkin et al. (editors), (Tomsk Scientific Center of the Russian Academy of Sciences, St.-Petersburg, 1993), pp. 263-270. Abstract: We discuss the different aspects and meanings of Mach's principle and present the consequences a dynamic model should lead in order to incorporate this principle. Then we analyse a Weber force law for gravitation from this point of view and conclude that it seems to be in full compliance with Mach's principle.
22. A. K. T. Assis, A steady-state cosmology, in: Progress in New Cosmologies: Beyond the Big Bang, H. C. Arp, C. R. Keys and K. Rudnicki (editors), (Plenum Press, New York, 1993), pp. 153-167. Abstract: We analyze a steady-state cosmology based on a boundless universe which has always existed and which is homogeneous on the very large scale. As this is a stationary model without expansion, it does not require a continous creation of matter, in contrast to the steady-state model of Bondi, Hoyle and Gold. We study the problems and properties of this model relating to inertia and gravitation (Mach's principle and the origin of inertia, the Seeliger-Neumann term), the cosmological redshift (alternatives to the Doppler interpretation of Hubble's law, the Finlay-Freundlich model), and the cosmic background radiation (predictions of a background temperature around 3K previous to the experimental discovery by Penzias and Wilson in 1965). Some observational tests of this general model are outlined.
21. A. K. T. Assis, Changing the inertial mass of a charged particle, Journal of the Physical Society of Japan, Vol. 62, pp. 1418-1422 (1993). Abstract: We calculate utilizing Weber's law the force on a moving charge exerted by a stationary charged spherical shell surrounding it. We obtain a net force different from zero which is proportional to the acceleration of the test particle relative to the spherical shell. This result can be interpreted by saying that the inertial mass of a test particle should change if it is placed inside a charged spherical shell. We conclude that this modification in the inertial mass is proportional to the electrostatic potential of the charged spherical shell and to the electric charge of the test particle. Then we present some possible experiments which could be performed to test this prediction.
20. A. K. T. Assis, Deriving gravitation from electromagnetism, Canadian Journal of Physics, Vol. 70, pp. 330-340 (1992). Abstract: We present a generalized Weber force law for electromagnetism including terms of fourth and higher orders in v/c. We show that these extra terms yield an attractive force between two neutral dipoles in which the negative charges oscillate around the positions of equilibrium. This attractive force can be interpreted as the usual Newtonian gravitational force as it is of the correct order of magnitude, is along the line joining the dipoles, follows Newton's action and reaction law, and falls off as the inverse square of the distance.
19. A. K. T. Assis and R. A. Clemente, The ultimate speed implied by theories of Weber's type, International Journal of Theoretical Physics, Vol. 31, pp. 1063-1073 (1992). Abstract: As in the last few years there has been a renewed interest in the laws of Ampère for the force between current elements and of Weber for the force between charges, we analyze the limiting velocity which appears in Weber's law. Then we make the same analysis for Phipps' potential and for generalizations of it. Comparing the results with the relativistic calculation, we obtain that these theories can yield c for the ultimate speed of charges or for the ultimate relative speed between the charges but not for both simultaneously, as is the case in the special theory of relativity.
18. A. K. T. Assis, On forces that depend on the acceleration of the test body, Physics Essays, Vol. 5, pp. 328-330 (1992). Abstract: We discuss Waldron's arguments against force laws that depend on the acceleration of the test body and show that they are incorrect. In contrast to Waldron's point of view, we show that these force laws are compatible with Newton's second law of motion.
16. A. K. T. Assis and F. M. Peixoto, On the velocity in the Lorentz force law, The Physics Teacher, Vol. 30, pp. 480-483 (1992). Subject: We discuss the historical origins of the magnetic force in the works of J. J. Thomson, O. Heaviside and H. A. Lorentz. We discuss the different meanings which have been employed historically to the velocity of the test charge which appears in this expression.
15. A. K. T. Assis, On the absorption of gravity, Apeiron, Vol. 13, pp. 3-11 (1992). Abstract: We proposed a modified Weber's potential for gravitation that takes into account the influence of intervening matter. Then we obtain equations of motion similar to Newton's first and second laws, and derive the proportionality between inertial and gravitational masses. We conclude that the gravitational absorprtion coefficient should be proportional to the square root of the density of the intervening mediu, and that for solids its value is approxiamtely 10^{-11} m^{-1}. All of this is accomplished supposing a limitless, homogeneous and stationary universe.
14. A. K. T. Assis, On the mechanism of railguns, Galilean Electrodynamics, Vol. 3, pp. 93-95 (1992). Abstract: Two mechanisms utilized to explain the operation of railguns are explained: one based on Ampère's force and the other on the transfer of momentum through electromagnetic waves. It is shown how the former is compatible with the data while the latter has problems with the quantitative figures and the case of the immobilized projectile.
13. A. K. T. Assis, On Hubble's law of redshifts, Olbers' paradox and the cosmic background radiation, Apeiron, Vol. 12, pp. 10-16 (1992). Abstract: We utilize the principle of conservation of energy in a model which explains the cosmological redshift, Olbers' paradox and the cosmic background radiation. The model is based on a hypothesis of absorption and emission of light by galactic and intergalactic matter, and a mean temperature of matter in the universe compatible with the background radiation. We also discuss the early works of Regener and Nernst related to these topics. Lastly we derive some known scaling laws for galaxies, i.e., luminosity to mass and luminosity to area, which had not been well understood up to now. All of this is accomplished supposing a boundless, stationary universe that is homogeneous on the large scale.
12. A. K. T. Assis, Centrifugal electrical force, Communications in Theoretical Physics, Vol. 18, pp. 475-478 (1992). Abstract: We calculate the force on a point charge moving within a charged spherical shell spinning with w(t) according to Weber's law. We compare this result with the one given by Lorentz's law and show that Weber's law predicts an extra centrifugal electrical force and an extra inertial electrical force. We give orders of magnitude for these forces and propose some experiments to test the existence of these terms.
11. R. A. Clemente and A. K. T. Assis, Two-body problem for Weber-like interactions, International Journal of Theoretical Physics, Vol. 30, pp. 537-545 (1991). Abstract: The problem of two moving bodies interacting through a Weber-like force is presented. Trajectories are obtained analytically once relativistic and quantic considerations are neglected. The main results are that in the case of limited trajectories, in general, they are not closed and in the case of open trajectories, the deflection angles are not the same for similar particles with given energies and angular momenta but opposite potentials. This last feature suggests the possibility of a direct verification of the validity of Weber's law of force for electromagnetic interactions.
10. A. K. T. Assis, Perplex numbers and quaternions, International Journal of Mathematical Education in Science and Technology, Vol. 22, pp. 555-562 (1991). Abstract: We present some properties of mathematical and physical interest in generalized algebras of two, three and four dimensions. We give a new formulation for these algebras, stress some important applications related to the wave equation, and emphasize a novel didactic approach to this subject.
9. A. K. T. Assis, Can a steady current generate an electric field?, Physics Essays, Vol. 4, pp. 109-114 (1991). Abstract: We present the results for the electric and magnetic fields due to linear and circular current distributions according to Weber's theory. We show how the electric field predicted by Weber's law is compatible with the anomalous diffusion in plasmas. Finally, we discuss some modern experiments related to this topic and compare the results of these experiments with a prediction based on Weber's law.
8. A. K. T. Assis and J. J. Caluzi, A limitation of Weber's law, Physics Letters A, Vol. 160, pp. 25-30 (1991). Abstract: We present Weber's law and its main properties. We discuss its relation with the experiments of mass variation with velocity. Then we calculate the energy and force on a charge moving inside and outside a capacitor according to Weber's electrodynamics. We discuss the consequences of this relation, and in particular we show that in this model a charge could attain velocities larger than the light velocity in a limited space due to a finite and feasible voltage difference. As this has never been observed we conclude that Weber's electrodynamics should not be applied to charges moving near the light velocity.
7. A. K. T. Assis, Modern experiments related to Weber's electrodynamics, in: Proceedings of the Conference on Foundations of Mathematics and Physics, U. Bartocci and J. P. Wesley (editors), (Benjamin Wesley Publisher, Blumberg, Germany, 1990), pp. 8-22. Abstract: We present Weber's force law and the classical results that follow from it. We discuss the historical controversy surrounding Ampère's law of force between current elements versus Grassmann-Biot-Savart's law. Then we make a review of modern experiments related to this topic and to the electric field generated by a steady and stationary neutral current. Finally we analyse some theoretical aspects of Weber's law as its extension through retarded potentials to include electromagnetic radiation, and its relation to alternative interpretations of experiments devised to show the mass variation with velocity.
6. A. K. T. Assis and P. H. Sakanaka, High frequency electromagnetic waves in a bounded, magnetized and warm plasma, Revista Brasileira de Física, Vol. 20, pp. 356-376 (1990). Abstract: The electromagnetic waves in a uniform, magnetized plasma, bounded by a cylindrical waveguide are studied using warm plasma theory. In the case of a cold plasma, backward electromagnetic waves are obtained which exhibit the phenomenon of Faraday rotation, in contrast to the Trivelpiece and Gould electrostatic modes which do not show this characteristic. Numerical results are presented for the linear LISA machine. A generalization of the Ghosh and Pal dispersion relation for a warm, magnetized plasma is derived.
5. P. H. Sakanaka and A. K. T. Assis, Mode conversion of global modes in a uniform cylindrical magnetized plasma, Proc. of the IV Latin-American Workshop on Plasma Physics, A. B. Rodrigo (ed.), (CNEA Editora, Buenos Aires, 1990), pp. 203-206. Abstract: The propagation of electromagnetic waves in a uniform magnetized plasma, bounded by a cylindrical conducting wall is studied using the two-fluid theory, with the pressure term included. Taking the cylindrical coordinates and perturbation of the form f(r)exp(ikz-intheta-iwt) we obtain a sixth order equation for the electric field component Ez(r). Its solution is a sum of three Bessel's or modified Bessel's functions. With appropriate boundary conditions, we obtain the dispersion relation which is solved numerically. The main result of this study is that the pressure term causes the mode conversion of a backward wave to another backward wave. The backward waves are modes which propagate in a frequency range between the plasma and upper-hybrid frequencies.
4. A. K. T. Assis, Deriving Ampère's law from Weber's law, Hadronic Journal, Vol. 13, pp. 441-451 (1990). Abstract: We correct some misconceptions in the literature regarding Weber's law and show: (A) with it Ampère's law of force between current elements can be derived with the modern current element, (B) what are the correct expressions for the relative velocity and acceleration between point charges, (C) why the acceleration terms in Weber's law are essential and so we have arguments to show that Ritz's law is untenable, and (D) how to develop the energy of interaction between two modern current elements.
3. A. K. T. Assis, Weber's law and mass variation, Physics Letters A, Vol. 136, pp. 277-280 (1989). Abstract: Due to the renewed interest of the last few years in Ampère and Weber's laws of force we decided to apply Weber's law to the situation of Bucherer's experiment. We calculate, according to Weber's expression, the force on a charge in regions of uniform electric and magnetic fields. Then we show that Weber's law agrees with the relativistic calculation only up to second order, inclusive, in v/c. So the special theory of relativity remains as the only model in perfect agreement with Bucherer's experiment.
2. A. K. T. Assis and P. H. Sakanaka, Dispersion relation of a bounded, magnetized and warm plasma, Proc. of the II Latin-American Workshop on Plasma Physics and Controlled Thermonuclear Fusion, R. Krikorian (ed.), (World Scientific Publications, Singapore, 1989), pp. 158-184. Abstract: The propagation of the electromagnetic waves in a cylindrical waveguide filled with uniform magnetized plasma is studied by the warm plasma theory. Dispersion relations are obtained for several situations, such as, zero and finite temperature, and zero, finite and infinite magnetic field. It is found that the waves can not be separated into transverse magnetic and transverse electric modes; only hybrid modes are propagated. For the case of finite magnetic field the Faraday's rotation is obtained.
1. A. K. T. Assis, On Mach's principle, Foundations of Physics Letters, Vol. 2, pp. 301-318 (1989). Abstract: We propose the postulate that the resultant force acting on any body is zero. With this postulate and with a Weber law for gravitation, we obtain equations of motion and conclude that all inertial forces are due to gravitational interaction with other bodies in the universe, as suggested by Mach. We then obtain the same value for the advance of the perihelion of the planets as is given by general relativity. All this is accomplished in a strictly relational theory. Finally, we relate these points to topical questions of electrodynamics raised by the experimental studies of Graneau and Pappas.
(B) Papers in Portuguese (artigos em português):
47. M. Faraday, Pesquisas experimentais em eletricidade, Caderno Brasileiro de Ensino de Física, Vol. 28, pp. 152-204 (2011), tradução de A. K. T. Assis e L. F. Haruna, DOI: 10.5007/2175-7941.2011v28n1p152. Resumo: Apresentamos uma tradução para o português do trabalho de Faraday de 1831 no qual ele apresenta sua descoberta fundamental da indução de correntes elétricas.
46. J. P. M. C. Chaib e A. K. T. Assis, A concepção dos elementos de corrente e da intensidade de corrente em Ampère, in: História da Ciência e Ensino: propostas, tendências e construção de interfaces, M. H. R. Beltran, F. Saito, R. N. d. Santos e W. Wuo (orgs.), (São Paulo, Ed. Livraria da Física, 2009), pp. 30-34. Conteúdo: São apresentadas as concepções de Ampère para os elementos de corrente e para a intensidade de corrente elétrica.
43. A. K. T. Assis, M. C. D. Neves e D. S. d. L. Soares, A cosmologia de Hubble: De um universo finito em expansão a um universo infinito no espaço e no tempo, in: M. C. D. Neves e J. A. P. d. Silva (Editores), Evoluções e Revoluções: O Mundo em Transição (Editora Massoni e LCV Edições, Maringá, 2008), pp. 199-221. Este artigo também saiu publicado na segunda edição deste livro: M. C. D. Neves e J. A. P. d. Silva (Editores), Evoluções e Revoluções: O Mundo em Transição (Editora Massoni e LCV Edições, Maringá, 2010, 2ª edição), pp. 215-237. Conteúdo: Mostramos a partir de seus trabalhos que Edwin Hubble mudou suas concepções cosmológicas. Inicialmente aceitava o modelo de um universo finito em expansão. Depois passou a defender o conceito de um universo que não se expande e que é infinito no espaço e no tempo.
40. J. Camillo e A. K. T. Assis, Construção de um gerador eletrostático gotejante: chuva elétrica de Kelvin, A Física na Escola, Vol. 9, pp. 29-32 (2008). Vídeo mostrando a faísca produzida nesta montagem. Conteúdo: Neste trabalho construímos um gerador eletrostático no qual a alta tensão é gerada pela queda de gotas de água que estão carregadas eletricamente, sendo armazenadas em recipientes isolados eletricamente da terra. Através de uma construção simples e de baixo custo, vários conceitos relacionados à eletrostática podem ser discutidos em diferentes níveis de ensino.
38. L. A. N. d. Paula, P. Raggio e A. K. T. Assis, Uma contribuição à construção de espelhos parabólicos, Caderno Brasileiro de Ensino de Física, Vol. 24, pp. 338-352 (2007). Resumo: Apresentamos um novo procedimento para a construção de espelhos parabólicos utilizando materiais de baixo custo. Construímos um sistema girante composto por fios de náilon, anzóis de pesca e uma bacia de plástico. Colocamos gesso líquido na bacia e a colocamos em rotação constante em relação à Terra. Um líquido adquire um perfil parabólico ao girar com uma velocidade angular constante em um referencial inercial na presença de um campo gravitacional uniforme vertical. Ao mantermos o gesso girando por um longo tempo, ele solidifica no formato parabólico. Usamos este parabolóide de gesso solidificado como modelo para construir um contra-molde de fibra de vidro e resina. Sobre este contra-molde esticamos papel laminado e em seguida despejamos gesso pastoso sobre ele. Com isto obtém-se um espelho parabólico feito de papel laminado e gesso. Nosso objetivo aqui é apenas o de apresentar um procedimento novo para a construção de espelhos parabólicos utilizando materiais de baixo custo. Isto permite que este procedimento seja explorado por professores e alunos de ensino médio e universitário.
37. M. P. Souza Filho, J. P. M. C. Chaib, J. J. Caluzi e A. K. T. Assis, Demonstração didática da interação entre correntes elétricas, Revista Brasileira de Ensino de Física, Vol. 29, pp. 605-612 (2007). Resumo: Apresentamos a primeira experiência crucial de Ampère mostrando a interação entre dois fios metálicos conduzindo correntes constantes. Discutimos sua importância na história da física. Descrevemos uma reprodução moderna dos procedimentos e observações de Ampère com materiais de baixo custo.
36. J. T. Lloyd, Lorde Kelvin demonstrado, Revista Brasileira de Ensino de Física, Vol. 29, pp. 499-508 (2007). Tradução de A. K. T. Assis. Resumo: Tradução do artigo Lord Kelvin demonstrated, The Physics Teacher 18, 16-24 (1980).
35. J. P. M. d. C. Chaib e A. K. T. Assis, Sobre os efeitos das correntes elétricas – Tradução comentada da primeira obra de Ampère sobre eletrodinâmica, Revista da Sociedade Brasileira de História da Ciência, Vol. 5, pp. 85-102 (2007). Resumo: Apresentamos a tradução comentada da primeira obra de A. M. Ampère sobre os fenômenos eletrodinâmicos. Neste artigo Ampère descreve suas observações da ação entre correntes elétricas e suas conseqüências qualitativas.
34. J. P. M. C. Chaib e A. K. T. Assis, Ampère e a origem do magnetismo terrestre, Anais do I Simpósio de Pesquisa em Ensino e História de Ciências da Terra e do III Simpósio Nacional sobre Ensino de Geologia no Brasil, P. W. Gonçalves et al. (orgs.), (Campinas, Instituto de Geociências da Unicamp, 2007), pp. 315-320. Resumo: Em 1820 Oersted descobriu que um longo fio com corrente alterava a orientação natural de uma agulha magnética colocada em suas proximidades. Ampère interpretou esta experiência como sendo devida a uma interação direta entre correntes elétricas existentes no ímã e no fio. Assim, para fundamentar sua posição, realizou uma série de experiências para estabelecer uma analogia entre os fenômenos magnéticos (interação entre ímãs ou entre ímãs e a terra) e os fenômenos que denominou de eletrodinâmicos (interação entre correntes). E no mesmo artigo em que apresentou experiências confirmando suas previsões, argumentou então que não existe razão em diferenciar a ação de um fio com corrente sobre um ímã, da ação magnética da terra sobre o mesmo ímã, ou mesmo da ação de um ímã sobre outro ímã. Ampère foi o primeiro a apresentar a hipótese de que o magnetismo terrestre é devido a correntes elétricas no interior da própria terra.
33. J. P. M. C. Chaib e A. K. T. Assis, Distorção da obra eletromagnética de Ampère nos livros didáticos, Revista Brasileira de Ensino de Física, Vol. 29, pp. 65-70 (2007). Resumo: Analisamos como alguns livros didáticos representativos apresentam a obra eletromagnética de Ampère. Mostramos que as informações apresentadas são distorcidas e que não correspondem à realidade histórica. Isto leva a uma visão errônea da evolução da física e da formulação de suas leis.
32. J. P. M. C. Chaib e A. K. T. Assis, Experiência de Oersted em sala de aula, Revista Brasileira de Ensino de Física, Vol. 29, pp. 41-51 (2007). Resumo: Em 1820 Oersted observou a deflexão de um pequeno ímã colocado próximo a um fio com corrente constante. Esta descoberta fundamental desencadeou uma série de pesquisas que levou à unificação dos fenômenos elétricos e magnéticos. Este artigo visa contribuir para o resgate da relevância da experiência de Oersted. É feita uma breve contextualização histórica desta experiência. Descreve-se uma reprodução moderna dos procedimentos e observações de Oersted com materiais de baixo custo.
31. A. K. T. Assis e J. P. M. C. Chaib, Nota sobre o magnetismo da pilha de Volta – tradução comentada do primeiro artigo de Biot e Savart sobre eletromagnetismo, Cadernos de História e Filosofia da Ciência, Vol. 16, pp. 303-309 (2006). Resumo: É feita uma tradução comentada do primeiro trabalho de Biot e Savart sobre eletromagnetismo. Eles passaram uma corrente constante em um longo fio retilíneo e observaram a posição de equilíbrio de uma pequena agulha imantada colocada próxima ao fio. Depois mediram o período para pequenas oscilações da agulha ao redor desta posição de equilíbrio, para diferentes distâncias da agulha ao fio. Concluíram que o torque magnético exercido pelo fio sobre a agulha é inversamente proporcional à distância entre o fio e o centro da agulha. Expressaram este fato em termos da força magnética exercida pelo fio sobre moléculas magnéticas na agulha. A força que atua sobre as moléculas seria perpendicular à linha ligando cada molécula ao fio e perpendicular ao eixo do fio, com sua intensidade sendo inversamente proporcional à distância ao fio.
30. A. K. T. Assis, Interações na física – ação à distância versus ação por contato, in: Estudos de História e Filosofia das Ciências: Subsídios para Aplicação no Ensino, C. C. Silva (org.), (Editora Livraria da Física, São Paulo, 2006), pp. 87-102. Resumo: Comparamos como ocorrem as interações na física de acordo com os modelos de ação à distância e de ação por contato.
28. A. K. T. Assis e W. Bagni Jr., Tradução de um texto de James Clerk Maxwell sobre a teoria das cargas-imagem, Caderno Brasileiro de Ensino de Física, Vol. 22, pp. 95-104 (2005). Resumo: Apresentamos uma tradução para o português de um importante trabalho de James Clerk Maxwell (1831-1879) publicado em 1881 sobre a teoria das cargas-imagem.
27. Arquimedes, Sobre o equilíbrio dos planos (segunda parte), introdução e tradução de A. K. T. Assis e N. B. F. Campos, Revista da Sociedade Brasileira de História da Ciência, Vol. 2, pp. 146-157 (2004). Resumo: Esta é a tradução da segunda parte do texto de Arquimedes sobre o equilíbrio dos planos. A primeira parte do trabalho foi publicada na Revista da Sociedade Brasileira de História da Ciência (n. 18, p. 81-94, jul./dez. 1997). Nesta segunda parte, o resultado mais importante obtido por Arquimedes é o centro de gravidade de um segmento parabólico.
26. A. C. Tort, A. M. Cunha e A. K. T. Assis, Uma tradução comentada de um texto de Maxwell sobre a ação a distância, Revista Brasileira de Ensino de Física, Vol. 26, pp. 273-282 (2004). Resumo: Apresentamos uma tradução comentada de um importante texto de James Clerk Maxwell publicado em 1873. Neste artigo Maxwell discute argumentos a favor e contra a ação a distância.
25. A. K. T. Assis, Tradução de uma obra de Gauss, Revista Brasileira de Ensino de Física, Vol. 25, pp. 226-249 (2003). Resumo: Apresentamos a primeira tradução para o português do trabalho fundamental de Gauss que é a base do sistema absoluto de medidas eletromagnéticas.
24. A. K. T. Assis e O. Pessoa Jr., Erwin Schrödinger e o princípio de Mach, Cadernos de História e Filosofia da Ciência, Vol. 11, pp. 131-152 (2001). Resumo: Apresentamos os conceitos de inércia, espaço e tempo na mecânica newtoniana. Analisamos o princípio de Mach, segundo o qual a inércia de qualquer corpo é devida a sua interação com os corpos distantes do universo. Em seguida explicamos porque, em geral, a teoria da gravitação de Einstein não implementa este princípio. Discutimos então o trabalho de Erwin Schrödinger que apresenta uma formulação alternativa para a mecânica baseada numa lei de Weber para a gravitação e que é compatível com as idéias de Mach.
23. J. A. Hernandes e A. K. T. Assis, Propagação de sinais em condutores segundo a eletrodinâmica de Weber, Ciência e Natura, Vol. 23, pp. 7-26 (2001). Resumo: Neste artigo calculamos a equação da telegrafia através da teoria eletrodinâmica de Weber. Isto é feito para condutores de diversos formatos. Comparamos os resultados obtidos com os preditos pelo eletromagnetismo clássico.
22. A. K. T. Assis, Comparação entre a mecânica relacional e a relatividade geral de Einstein, in: Fundamentos da Física 2 - Simpósio David Bohm, O. Pessoa Jr. (organizador), (Editora da Livraria da Física, São Paulo, 2001), pp. 27-38. Resumo: Apresenta-se o conceito de inércia como formulado por Newton e dois resultados fundamentais que obteve com sua lei da gravitação universal: a força resultante exercida por uma casca esférica num ponto material dentro ou fora dela. Utilizam-se estes resultados para analisar sua famosa experiência do balde. Discutem-se as críticas de Mach à formulação newtoniana da inércia e sua interpretação da experiência do balde. Apresentam-se as opiniões de Einstein sobre estes temas e os resultados obtidos com a Relatividade Geral. Comparam-se criticamente estes resultados com aqueles obtidos pela força de Weber para a gravitação.
21. A. K. T. Assis, A primeira medida eletromagnética da velocidade da luz por Weber e Kohlrausch, Anais do VII Seminário Nacional de História da Ciência e da Tecnologia, J. L. Goldfarb e M. H. M. Ferraz (organizadores), (Editora da Universidade de São Paulo, Editora da Unesp, Imprensa Oficial do Estado, Sociedade Brasileira de História da Ciência, São Paulo, 2000), pp. 65-71. Resumo: Neste trabalho analiso a primeira medida experimental da razão entre a unidade eletrodinâmica e a unidade eletrostática de carga, realizada por Weber e Kohlrausch em 1855-56. Com isto obtiveram também a razão entre as unidades eletromagnética e eletrostática de carga, que é a quantidade anterior dividida por raiz quadrada de 2. Esta última grandeza teve como valor experimental 3 X 10^8 m/s, que é o mesmo valor que a velocidade da luz no vácuo. Discuto também o significado desta grandeza na eletrodinâmica de Weber e seu aparecimento em 1846. São apresentados e comparados diversos sistemas de unidades. Analisa-se também os trabalhos independentes de Weber e Kirchhoff, de 1857, sobre a propagação de sinais eletromagnéticos em condutores metálicos. Ambos obtiveram a partir da eletrodinâmica de Weber que estes sinais caminham em circuitos de baixa resistividade com a velocidade da luz no vácuo. Tudo isto foi feito antes de Maxwell desenvolver sua teoria eletromagnética da luz em 1861-64.
20. J. A. Hernandes e A. K. T. Assis, Propagação de sinais em condutores com a eletrodinâmica de Weber e comparação com o eletromagnetismo clássico, Anais do XXI Encontro Nacional de Física de Partículas e Campos (23 a 27/10/2000, São Lourenço, MG). Resumo: Neste trabalho apresentamos um estudo sobre a equação da telegrafia, pioneiramente obtida por Kirchhoff e Weber. Seguimos o procedimento adotado por Kirchhoff para derivar esta equação. Consideramos casos não tratados na literatura. Concluímos que a teoria de Weber leva à equação da telegrafia.
19. A. K. T. Assis, Discriminação na ciência, in: Discriminação, editores: M. T. Viana e L. O. L. Renault (Editora LTR, São Paulo, 2000), pp. 285-297. Este trabalho também foi publicado na segunda edição deste livro: A. K. T. Assis, Discriminação na ciência, in: Discriminação, editores: L. O. L. Renault, M. T. Viana e P. O. Cantelli (Editora LTR, São Paulo, 2a edição, 2010), pp. 390-400. Resumo: São discutidos aspectos sociais, educacionais e lingüistícos ligados com a discriminação na ciência. São analisados aspectos de discriminação exercidos pelos próprios cientistas contra outros cientistas.
18. A. K. T. Assis e J. A. Hernandes, Cargas superficiais em placas condutoras com correntes constantes, Anais do XX Encontro Nacional de Física de Partículas e Campos (25 a 29/10/99, São Lourenço, MG). Resumo: Estudamos a existência de campos elétricos fora de condutores com corrente constante e sua relação com as cargas superficiais que geram as correntes. Obtemos resultados novos para condutores em forma de placas. Comparamos nossos resultados teóricos com dados experimentais.
17. A. K. T. Assis e J. A. Hernandes, A repulsão coulombiana não explica o fenômeno da explosão de fios, Acta Scientiarum, Vol. 21, pp. 837-839 (1999). Resumo: Neste artigo, consideramos o fenômeno da explosão de fios que acontece quando flui uma alta corrente elétrica. Apresentamos o resultado da tensão coulombiana. Esta tensão é gerada pelo aparecimento de densidades de carga no fio, devido ao efeito Hall radial. Concluímos que esta tensão é várias ordens de grandeza inferior àquela necessária para romper um fio metálico.
16. A. Zylbersztajn e A. K. T. Assis, Sobre a possível realidade das forças fictícias: uma visão relacional da mecânica, Acta Scientiarum, Vol. 21, pp. 817-822 (1999). Resumo: Com base no princípio de Mach, pode-se considerar as forças de inércia, também chamadas forças fictícias, como reais. Neste artigo, apresentamos as idéias de Mach no contexto histórico das críticas à noção newtoniana de espaço absoluto e analisamos a Primeira Lei de Newton, normalmente aceita sem maiores discussões no ensino da mecânica. A seguir, mostramos como aquelas idéias podem ser quantitativamente implementadas através de uma mecânica relacional, segundo a qual as forças de inércia são interpretadas como resultando das interações entre massas locais e a matéria distante no universo. Algumas implicações para o ensino são mencionadas na conclusão.
15. A. K. T. Assis, Discussão sobre o conceito de ciência, Episteme, Vol. 9, pp. 127-129 (1999). Resumo: Resenha do livro O Que É Uma Teoria Científica? - Uma Breve Provocação Sobre Um Tema Complexo, de Jenner B. Bastos Filho (Edufal, Maceió, 1998), 144 páginas.
14. A. K. T. Assis, Resenha de livro: Circuitos Elétricos, Magnéticos e Teoria Eletromagnética, por Y. Burian Jr., Boletim Eletrônico da Sociedade Brasileira de Matemática Aplicada e Computacional, Vol. III (1999). Resumo: Resenha do livro Circuitos Elétricos, Magnéticos e Teoria Eletromagnética, de Yaro Burian Jr. (Ábaco Livraria Ltda., Faculdade de Engenharia Elétrica e de Computação da Unicamp, Campinas, 1996), 101 páginas.
13. A. K. T. Assis, Resenhas - O Mago que Veio do Céu, por M. C. D. Neves e L. R. Gardesani, Revista Brasileira de Ensino de Física, Vol. 21, pp. 556-557 (1999). Resumo: Resenha do livro O Mago que Veio do Céu, de M. C. D. Neves, com ilustrações de L. R. Gardesani (EDUEM, Maringá, 1998), 72 páginas.
12. A. K. T. Assis, O conceito de massa na mecânica relacional e na relatividade geral, in: Anais do IV Simpósio de Pesquisa e Extensão em Tecnologia (Centro de Tecnologia - UFRN - Natal, 1999), Seção 7, páginas 191-192, editores: H. C. C. Fernandes, L. F. F. Moreira e A. R. O. Guerra. Resumo: Mostramos que massa é um conceito absoluto tanto na mecânica clássica quanto na teoria da relatividade geral de Einstein. Este aspecto foi criticado por Ernst Mach, que acreditava que a massa devia ser um conceito relativo na física (apenas razões de massas deviam ser importantes nos fenômenos). Mostramos que com a mecânica relacional as idéias de Mach são implementadas quantitativamente.
11. A. K. T. Assis, Newton e suas grandes obras: o Principia e o Óptica, in: Linguagens, Leituras e Ensino da Ciência, M. J. P. M. de Almeida and H. C. da Silva (editors), (Mercado de Letras/Associação de Leitura do Brasil, Campinas, 1998), pp. 37-52. Assunto: Comparam-se as semelhanças e diferenças dos dois principais livros publicados por Isaac Newton, o Principia e o Óptica.
10. A. K. T. Assis, Comparação entre as eletrodinâmicas de Weber e de Maxwell-Lorentz, Episteme, Vol. 3, pp. 7-15 (1998). Resumo: Ampresentam-se as origens históricas e comparam-se as principais características e propriedades das eletrodinâmicas desenvolvidas por Weber e por Maxwell-Lorentz. A primeira baseia-se diretamente nas cargas elétricas e na interação entre elas, enquanto que a segunda tem como base os campos elétricos e magnéticos. Discutem-se nestas duas teorias as leis de conservação e de ação e reação, assim como a propagação de sinais eletromagnéticos. Analisam-se experiências que podem distinguir estas duas eletrodinâmicas, em particular uma casca esférica uniformemente carregada com uma partícula teste sendo acelerada em seu interior por outros corpos. De acordo com a eletrodinâmica de Weber a casca deve atuar sobre a partícula teste, o que não deve ocorrer de acordo com a eletrodinâmica de Maxwell-Lorentz já que a casca carregada não gera campos elétricos nem magnéticos em seu interior. São fornecidas ordens de grandeza para estes efeitos e discutidos os aspectos filosóficos destas duas teorias.
9. A. K. T. Assis, Sobre o equilíbrio dos planos, tradução comentada de um texto de Arquimedes, Revista da Sociedade Brasileira de História da Ciência, Vol. 18, pp. 81-94 (1997). Resumo: Esta é uma tradução do tratado de Arquimedes intitulado Sobre o Equilíbrio dos Planos ou Sobre o Centro de Gravidade dos Planos. Neste trabalho Arquimedes apresenta um dos princípios fundamentais da estática, a lei da alavanca.
8. A. L. Xavier Jr. and A. K. T. Assis, Schrödinger, Reissner, Weber e o princípio de Mach, Revista da Sociedade Brasileira de História da Ciência, Vol. 17, pp. 103-106 (1997). Resumo: Apresentamos uma tradução comentada de um texto de Erwin Schrödinger sobre seu artigo intitulado O cumprimento do postulado de relatividade na mecânica clássica, trabalho que já traduzimos para o português.
7. A. K. T. Assis, Resenha de livro: La Mécanique de Lagrange - Principes et Méthodes, Revista da Sociedade Brasileira de História da Ciência, Vol. 18, pp. 95-96 (1997). Resumo: Resenha do livro La Mécanique de Lagrange - Principes et Méthodes, de Wilton Barroso Filho, Éditions Karthala, Paris, 1994, 333 páginas, ISBN: 2-86537-482-3.
6. A. K. T. Assis, A experiência do balde de Newton, in: Reflexões sobre os Fundamentos da Física Moderna, A. F. Siqueira and J. B. Bastos Filho (eds.), (Edufal, Maceió, 1997), pp. 49-61. Assunto: Discute-se a experiência realizada por Newton, as críticas à interpreção de Newton apresentada por Ernst Mach e como esta experiência é interpretada na mecânica relacional.
5. A. K. T. Assis, Sobre os corpos flutuantes - tradução comentada de um texto de Arquimedes, Revista da Sociedade Brasileira de História da Ciência, Vol. 16, pp. 69-80 (1996). Resumo: Esta é uma tradução do tratado de Arquimedes intitulado Sobre os Corpos Flutuantes. Neste trabalho Arquimedes apresenta o princípio fundamental da hidrostática.
4. A. K. T. Assis, A eletrodinâmica de Weber e seus desenvolvimentos recentes, Ciência e Natura, Vol. 17, pp. 7-16 (1995). Resumo: É apresentada a eletrodinâmica desenvolvida por Wilhelm Weber e suas principais propriedades (conservação do momento linear, do momento angular e da energia). Indica-se o fato de se derivar as equações de Maxwell a partir da eletrodinâmica de Weber. Também a força entre elementos de corrente de Ampère pode ser derivada a partir dela. Apresentam-se resultados experimentais relacionados com a eletrodinâmica de Weber tais como: experimentos ligados com a força de Ampère e com a força de Grassmann-Biot-Savart; e a existência ou não de um campo elétrico devido a uma corrente elétrica neutra, constante e estacionária. Por último discute-se desenvolvimentos recentes da eletrodinâmica de Weber: introdução do tempo retardado; a existência de termos de ordem superior a v^2/c^2; e a possibilidade de derivação da gravitação a partir de uma generalização da força de Weber.
2. A. K. T. Assis, Teorias de ação a distância - Uma tradução comentada de um texto de James Clerk Maxwell, Revista da Sociedade Brasileira de História da Ciência, Vol. 7, pp. 53-76 (1992). Resumo: Apresentamos uma tradução comentada do último capítulo do livro A Treatise on Electricity and Magnetism, de J. C. Maxwell. Neste capítulo Maxwell discute as teorias eletromagnéticas de ação a distância proposta por Gauss, Weber, Riemann, Neumann, etc. Comentamos o trabalho de Maxwell e enfatizamos a relação de vários dos tópicos aqui discutidos com experimentos recentes ligados com a eletrodinâmica clássica.
1. A. K. T. Assis, Wilhelm Eduard Weber (1804-1891) - Sua vida e sua obra, Revista da Sociedade Brasileira de História da Ciência, Vol. 5, pp. 53-59 (1991). Resumo: É apresentada a vida de Weber, suas principais realizações experimentais e teóricas, e os desenvolvimentos recentes de sua teoria.
2. A. K. T. Assis, The unit of the angle and the angular equations, Revista Physicae, Vol. 1, pp. 55-56 (2000). Abstract: It is shown that angle has unit like any other physical quantity. It is presented a procedure to write down all angular equations taking this into account and valid for degrees, radians and grades.
1. A. K. T. Assis, Números perplexos, (paper in Portuguese), The Gleb Times (Jornal do Centro Acadêmico de Física da Unicamp), Ano 1, Número 2, p. 11 (1994). Assunto: Discutimos a relação entre os números complexos e os números perplexos.
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Address:
Institute of Physics
University of Campinas - UNICAMP
13083-859 Campinas, SP
Brazil
Telephone: (+55) (19) 35215515
Fax: (+55) (19) 35215512
E-mail: assis@ifi.unicamp.br Homepage: http://www.ifi.unicamp.br/~assis
Endereço:
Instituto de Física
Universidade Estadual de Campinas - UNICAMP
13083-859 Campinas, SP
Brasil
Telefone: (+55) (19) 35215515
Fax: (+55) (19) 35215512
E-mail: assis@ifi.unicamp.br Homepage: http://www.ifi.unicamp.br/~assis
