Blog Ekkehard Friebe

Ich nehme Bezug auf meinen Blog-Eintrag: Nikolai Rudakov: „Establishment”. Aus dem dort genannten Buch (1981): „Fiction stranger than truth – In the metaphysical labyrinth of relativity” von Nikolai Rudakov bringe ich nachstehend eine weitere Leseprobe:

Zitat:

6 Electrodynamics

Einstein’s 1905 paper, commonly regarded as the document which gave birth to the theory of relativity, has the title On the Electrodynamics of Moving Bodies. When the paper was published, the title did not attract any attention. In retrospect, however, it looks highly incongruous because the title of Einstein’s paper cannot be regarded as exactly or even largely representative of its thesis (Keswani). The paper consists of a short introduction, a kinematical part and an electrodynamical part. The emphasis appears to be on electrodynamics, and the purpose of the kinematics is to serve as a theoretical framework. Einstein says that the theory to be developed is based — like all electrodynamics — on the kinematics oft he rigid body, and then proceeds to show how his particular set of kinematic ideas can be applied to Maxwell’s equations and some other randomly selected phenomena from electricity and optics.

Within two years after the publication of the paper the electrodynamical considerations dropped completely out of sight as can be seen in Einstein’s contribution to an annual review in 1907 under the title On the Principle of Relativity and the Conclusions Drawn from It. Only the kinematical part remained and gradually transformed itself into the special theory of relativity. However, the origin and nature of Einstein’s theory cannot be properly understood without an examination of its relationship with electrodynamics, and this means with Maxwell’s theory of electro-magnetism. Einstein’s theory was conceived on the basis of Maxwell’s equations, and the Michelson-Morley experiment, and the idea is still kept alive that electrodynamics is a branch of physics in which relativity has proved its validity.

The introductory section of the 1905 paper commences with the words: It is known that Maxwell’s electrodynamics — as usually understood at the present time — when applied to moving bodies, leads to asymmetries which do not appear to be inherent in the phenomena. Einstein’s point of departure is Maxwell’s theory. He is concerned with asymmetries in it which are not in accordance with experience, and it is for the specific purpose of eliminating these assumed asymmetries that he proposes his theory. Einstein’s complaint derives from the historically separate development of electricity and magnetism leading to the discoveries of Oersted and Faraday. Oersted observed that an electric current deflects a magnetic needle, and Faraday that a rotating magnet induces an electric current. In other words, electric currents produce magnetic effects and magnets produce electric currents. Although Maxwell combined electricity and magnetism in bis theory, he retained the conceptual Separation between electric and magnetic components because it made sense in physical terms. What Einstein is criticising is this conceptual Separation which prevents the complete reciprocity of the effects from being properly appreciated. He thinks that the fault should be rectified by changing the mathematical formalism. He maintains that his method is mathematically simpler, although his conception of simplicity does not lead to any better under-standing of electromagnetic processes. In fact, Einstein’s formulation of the electromagnetic equations is more difficult than Maxwell*s and has no demonstrable advantages whatsoever. Physicists could hardly consider the separate study of electric and magnetic phenomena äs a fault because these phenomena are separate in nature and there is an eminently practical reason to leave them apart. Yet some relativists assert that Einstein noted a contradiction in contemporary scientific beliefs apparent for years but conveniently ignored (Clark). It is wrong to say that there was a contradiction in Faraday’s law of induction (Clark). Faraday’s law was not incompatible with Oersted’s discovery and, in any case, Maxwell indicated how the two threads hung together. Einstein’s problem was a non-problem, but it served as one of the two starting points for the special theory, the other being the Michelson-Morley experiment.

Between 1864 and 1873 Maxwell, after studying Faraday’s work and other developments in electricity and magnetism, proposed a mechanical model of the mutual interaction of electrical and magnetic phenomena and then, using this model as a basis, expressed the interaction in mathematical equations. Maxwell’s theory not only combined electrical and magnetic phenomena and established the concept of the electromagnetic field, but also predicted the existence of electromagnetic waves and opened the way for other developments in modern physics. Faraday had discovered that a moving magnet produces an electric current in a conductor in its vicinity. Maxwell’s model indicated that in the absence of a conductor a displacement, signifying a current, occurs in the medium surrounding the magnet. The model also indicated that a displacement, in turn, gives rise to a magnetic effect. This corresponds, basically, to Oersted’s discovery. As it was difficult to imagine a displacement in empty space, Maxwell supported the hypothesis that the medium surrounding magnets and conductors, and space in general, was filled with a quasi-mechanical substance of very low density and at the same time very high elasticity. This substance was referred to as aether and had a definite purpose in Maxwell’s model although physical evidence of its existence was lacking. Maxwell’s mechanical model is now forgotten or, if it is mentioned, considered to be crude and childish. But the fact is that he derived a series of mathematical equations from his model which summarised concisely and effectively the fundamental laws of electricity and magnetism. Field intensity vectors specify what is happening electromagnetically at every point in space in relation to conductors and magnets.

(Zitatende)

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Beste Grüße Ekkehard Friebe