After G. N. Lewis (1875-1946) proposed the term “photon” in 1926, many physicists adopted it as a more apt name for Einstein’s light quantum. However, Lewis’ photon was a concept of a very different kind, something few physicists knew or cared about. In fact, it turns out that the term “photon” was not novel, as the same term was proposed or used earlier, apparently independently, by at least four other scientists. Three of the four early proposals were related to physiology or visual perception, and only one to quantum physics. Priority belongs to the American physicist and psychologist L. T. Troland (1889-1932), who coined the word in 1916, and five years later it was independently introduced by the Irish physicist J. Joly (1857-1933). Then in 1925 a French physiologist, René Wurmser (1890-1993), wrote about the photon, and in July 1926 his compatriot, the physicist F. Wolfers (ca. 1890-1971), did the same in the context of optical physics. None of the four pre-Lewis versions of “photon” were well known and they were soon forgotten., Kdy se objevil termín "foton" a v jakém kontextu? O tom pojednává tento článek významného dánského historika fyziky H. S. Kragha. Obecně se soudí, že za "foton" vděčíme slavnému americkému chemikovi G. N. Lewisovi, který tento termín stvořil roku 1926. Je to pravda, ale Kragh ukazuje jednak, že to bylo v jiném kontextu, než jak chápeme foton dnes, jednak, že několik jiných badatelů navrhlo a použilo termín foton již před Lewisem - na ně se však zapomnělo. Nakonec tedy můžeme konstatovat, že "foton" se zrodil několikrát v období deseti let zhruba před sto lety. (jv), Helge S. Kragh., and Obsahuje bibliografické odkazy
The western part of the Bohemian Massif (Vogtland/West-Bohemia region at the Czech-German border) is characterized by relatively frequent intraplate earthquake swarms and by other manifestations of current geodynamic activity, such as mofettes, mineral and thermal springs. In this study we analyze variations of groundwater level in four hydrological wells in the region during the years 2005-2010. Monitoring during the previous time interval of 2000-2004 is also mentioned and used for comparison. Two of the wells are located in the epicentral region of Nový Kostel, and the other wells are more distant. The time interval includes the 2008 earthquake swarm when all the wells displayed a noticeable drop in the water level. This effect was observed up to epicentral distances of nearly 30 km, which exceeds the distances of hydrological changes observed during previous earthquake swarms. Moreover, it seems that a small rise in the water level preceded the intervals of increased seismic activity, which could represent a certain precursory phenomenon. On the other hand, the hydrological changes in the Nový Kostel area were relatively small, indicating that this epicentral area is not hydrologically linked with the seismically active fault at depth. Consequently, more suitable localities for hydrological monitoring should be sought in a broader vicinity of Nový Kostel., Renata Gaždová, Oldřich Novotný, Jiří Málek, Jan Valenta, Milan Brož and Petr Kolínský., and Obsahuje bibliografii
The history of semiconductor injection lasers is briefly outlined and the need for lasers integrated on Si chips is explained. Several approaches to overcome inadequate properties of silicon are followed; including (i) silicon nanocrystals and other lowdimensional structures (ii) Si Raman laser, (iii) rare-earth doped Si, and (iv) non-silicon-material lasers integrated to Si chips. Finally, the recent germanium laser is described., Jan Valenta., and Obsahuje bibliografii