History of Cosmic Magnetic Fields
2023; Springer International Publishing; Linguagem: Inglês
10.1007/978-3-031-29493-8_16
ISSN2509-310X
Autores Tópico(s)Gamma-ray bursts and supernovae
ResumoMagnetic fields are not obvious; the attraction of an apple by the Earth is visible. The action of a magnet on an iron plate is less obvious. Gravitation, as explained by Isaac Newton, was easily understood. The reason for attraction of a metallic object by a lodestone was known but needed time for an explanation. Records of the action of magnetic fields are found in the works of ancient Greeks, Romans and Chinese. The later explanation of magnetism and electricity contributed enormously to the development of present day civilization. Here we have numerous important discoverers: Thales of Miletus, William Gilbert, Johannes Kepler, Hans Christian Oersted, James Clerk Maxwell, Carl Friedrich Gauss, Heinrich Hertz, Werner von Siemens and many others, who made fundamental contributions. The discovery of magnetic fields outside the Earth was made first by observations of the Sun. The solar storms result in clear arcs that were associated with action of magnetic fields. In 1886 Pieter Zeeman showed that spectral lines are split by magnetic fields. This became a method of measuring magnetic fields in the Cosmos. In fact the first real measurement of the magnetic field in Sunspots was made by the use of the Zeeman Effect. The next development was the observation of optical polarization. Some researchers suggested that this happens due to alignment of dust particles by magnetic fields, others said that this may be only an effect of scattering. The discovery of radio waves and their interpretation as synchrotron radiation finally cleared up the controversy. Yes, magnetic fields are seen in Galactic objects like supernova remnants, in radio galaxies or even in the diffuse Galactic radio emission. A final confirmation of the Zeeman Effect in radio clinched our understanding, yes the optical observations gave information about magnetic fields.
Referência(s)