Symmetries in physics are most commonly recognized and discussed in terms of their function in the mathematical formalism of the theories. Discussion of the observation of symmetries in nature is less common. This paper analyses the observation of particular symmetries such as Lorentz and gauge symmetries, distinguishing between direct observation of the symmetry itself and indirect evidence, the latter being the observation of some consequence of the symmetry are, in an important sense, directly observed, while local symmetries such as gauge (...) symmetry are not. (shrink)

The constrained Hamiltonian formalism is recommended as a means for getting a grip on the concepts of gauge and gauge transformation. This formalism makes it clear how the gauge concept is relevant to understanding Newtonian and classical relativistic theories as well as the theories of elementary particle physics; it provides an explication of the vague notions of “local” and “global” gauge transformations; it explains how and why a fibre bundle structure emerges for theories which do not wear their bundle structure (...) on their sleeves; it illuminates the connections of the gauge concept to issues of determinism and what counts as a genuine “observable”; and it calls attention to problems which arise in attempting to quantize gauge theories. Some of the limitations and problematic aspects of the formalism are also discussed. (shrink)

It has long been a commonplace that there is a problem understanding the role of time when one tries to quantize the General Theory of Relativity (GTR). In his "Thoroughly Modern McTaggart" (Philosophers' Imprint Vol 2, No. 3), John Earman presents several arguments to the conclusion that there is a problem understanding change and the passage of time in the unadorned GTR, quite apart from quantization. His Young McTaggart argues that according to the GTR, no physical magnitude ever changes. A (...) close consideration of Young McTaggart's arguments show that they turn on either a bad choice of formalism or an unwarranted interpretation of the implications of the formalism. This suggests that the problems that arise in quantization may be founded in similar shortcomings. (shrink)

The aim of the article is to present historiographical analysis of researches of Russian historians of the XIX - early XX centuries. The view point of Russian scientists on hetman I. Briukhovetsky and his activities is considered. Common features in their concepts are revealed. The proposed by the Russian historians motivation of the hetman`s activity is analyzed. Russian historians paid attention to the visit of I. Briukhovetsky to Moscow in 1665 (the first ever visit of Ukrainian hetman of the Russian (...) capital), and to the hetman`s "petition", which contained the request for limitation of Ukrainian autonomy. S. Solovyev, G. Karpov, P. Matveev explained hetman`s action suchwise that he sought to gain outer support in the Moscow government. Approximately the same idea had M.Pokrovsky. S. Solovyev compared I. Briukhovetsky with I. Vyhovsky, who also sought to outer support, but focused not on Russia but on Poland. Thus, Russian historians explained the cause of I. Briukhovetsky`s betrayal as his political mistakes. Russian historians admitted that the revolt at the time was quite natural, as Left-bank Ukraine was dissatisfied with the policy of the royal government. They also considered the death of I. Briukhovetsky to be natural, as he managed to alienate all social layers in Ukraine during his reign, Cossacks as well. (shrink)