History of variational principles in physics involves integrals over an interval of time and (for fields) extended region of space. Moreover, in the usual formulation of classical action principles, the initial and final states of the system are fixed, e.g., In particular, the fixing of the "final" state appears to give the action principle a teleological character which has been controversial historically. This apparent teleology is eliminated in the quantum mechanical version of the action principle. History of variational principles in physics A variational principle in physics is an alternative method for determining the state or dynamics of a physical system, by identifying it as an
Bulletin of the Lebedev Physics Institute Bulletin of the Lebedev Physics Institute Bulletin of the Lebedev Physics Institute (Russian: "Краткие сообщения по физике", "Kratkue Soobsheniya po fisike") is a peer-reviewed scientific journal of physics. The journal was established in 1970, and is published by the Lebedev Physical Institute (in Russian) a monthly basis. Springer publishes an English translation of the journal. It is edited by Oleg N. Krokhin. The online version is available since 2007. The "Bulletin" covers research results from Prokhorov General Physics Institute and the Institute for Nuclear Research of the Russian Academy of Sciences in addition to those of the Lebedev Physical Institute.