The sub-title of this symposium is accurate and, in a curious way, promises more than it states: Classical Physicist, Modem Philosopher. Heinrich Hertz, as the con­ summate experimentalist of 19th century technique and as brilliant clarifying critic of physical theory of his time, achieved one of the fulfilments but at the same time opened one of the transition points of classical physics. Thus, in his 'popular' lecture 'On the Relations Between Light and Electricity' at Heidelberg in the Fall of 1889, Hertz identified the ether as henceforth the most fundamental problem of physics, as the conceptual mystery but also the key to understanding mass, electric­ ity, and gravity. Of Hertz's demonstration of electric waves, Helmholtz told the Physical Society of Berlin: "Gentlemen! I have to communicate to you today the most important physical discovery of the century. " Hertz, philosophizing in his direct, lucid, pithy style, once wrote "We have to imagine". Perhaps this is metaphysics on the horizon? In the early pages of his Principles of Mechanics, we read A doubt which makes an impression on our mind cannot be removed by calling it metaphysical: every thoughtful mind as such has needs which scientific men are accustomed to denote as metaphysical. (PM23) And at another place, concerning the terms 'force' and 'electricity' and the alleged mystery of their natures, Hertz wrote: We have an obscure feeling of this and want to have things cleared up.

Inhalt

Preface; R.S. Cohen. Hertz, Helmholtz and Their Experimental Culture. Heinrich Hertz and the Berlin School of Physics; D. Hoffmann. From Helmholtz's Philosophy of Science to Hertz's Picture-Theory; M. Heidelberger. The Loss of World in the Image: Origin and Development of the Concept of Image in the Thought of Hermann von Helmholtz and Heinrich Hertz; G. Schiemann. Electrodynamics and the Discovery of Electromagnetic Waves. Heinrich Hertz's Experiments and Experimental Apparatus: His Discovery of Radio Waves and His Delineation of their Properties; J. Bryant. Hertz's Study of Propagation vs. Rutherford's Study of Structure: Two Modes of Experimentation and their Theoretical Underpinnings; G. Hon. On Hertz's Conceptual Conversion: From Wire Waves to Air Waves; M. Doncel. The Principles of Mechanics. Hertz's View on the Methods of Physics: Experiment and Theory Reconciled? S. D'Agostino. Hertz and the Geometrization of Mechanics; J. Lützen. Hertz's Principles; S. Saunders. `Everything Could be Different': The Principles of Mechanics and the Limits of Physics; A. Nordmann. Hertz's Influence on Twentieth Century Science and Philosophy. The Reception of Heinrich Hertz's Principles of Mechanics by his Contemporaries; J. Mulligan. Heinrich Hertz's Mechanics: A Model for Werner Heisenberg's April 1925 Paper on the Anomalous Zeeman Effect; K. Hentschel. Heinrich Hertz's Picture-Conception of Theories: Its Elaboration by Hilbert, Weyl, and Ramsey; U. Majer. Hertz's Philosophy of Nature in Wittgenstein's Tractatus; G. Graßhoff. Afterword. Reflections and Reactions; J. Buchwald. Bibliography. Concordance and Index of Passages. Name Index.