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Barringer Invitational Lecture. Magnetism in the Universe. A.P. Guimarães Centro Brasileiro de Pesquisas Físicas Rio de Janeiro, Brazil http://www.cbpf.br/~labmag /. Why the Fascination of Magnetism?.
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Barringer Invitational Lecture Magnetism in the Universe A.P. Guimarães Centro Brasileiro de Pesquisas Físicas Rio de Janeiro, Brazil http://www.cbpf.br/~labmag/
“A wonder of such nature I experienced as a child of 4 or 5 years, when my father showed me a compass.” A. Einstein, Autobiographical Notes, in Albert Einstein: Philosopher-Scientist, vol. I, Ed. P.A. Schilpp, Cambridge University Press, London, 1969, p. 9.
The Sources of Magnetism • Electric currents generate magnetic fields • Magnetism of matter arises from atomic currents and the electron spin
For How Long have Magnetic Phenomena been Known? • ????? • List of commodities in Mesopotamia, including magnetite, described as šadânu sabitu (‘hematite that grasps’) (2000-1500 BC)
Epistola de Magnete (1269) Petrus Peregrinus (?1220) • Peregrinus served in the army of Charles d’Anjou(Charles I)(1226-1285), probably as an engineer • Siege of Lucera, in Italy
Epistola de Magnete (1269) Petrus Peregrinus • Identified and gave names to the poles • Attraction and repulsion • Magnetization of iron by contact • Described ‘wet’ and ‘dry’ compasses • Loadstone connected to the heavens (‘virtuscoeli’)
De Magnete (1600) • Importance of magnetism at the time • Sum of existing knowledge on magnetism • Experimental observations with the loadstone • One of the first scientific treatises
William Gilbert (1544-1603) Elizabeth I (1558-1603) Terrella Gilbert
Magnus magnes ipse est globus terrestris… • The Earth is a great magnet...
Electricity and Magnetism, the Unification: Oersted and Ampère • Ampère:magnetic bodies and electric currents • The experiment of Oersted(1820)
Electricity and Magnetism, the Unification: Michael Faraday(1791-1867) • Discovery of induction • Types of substances (diamagnetic, paramagnetic, ferromagnetic) • Field lines • The concept of field