The Racah Institute of Physics aspects related to high-Tc superconductivity. On the experimental side, benefiting from the facilities of the Harvey M. Krueger center for nanoscience and nanotechnology, researchers apply modern measuring and fabrication techniques to study the physics of nano-structures, their application to quantum information processing, the interaction of light and matter, high-Tc superconductivity, and the physics of electron glasses. More specifically, and summarizing but a few of the research directions, researchers study excitonic fluids in semiconductor nanostructures with an eye on both a better physical understanding of their macroscopic quantum coherence properties and possible future applications in electro-optic devices. Josephson junctions are being
History of variational principles in physics 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 extremum (minimum, maximum or saddle point) of a function or functional. This article describes the historical development of such principles. Variational principles are found among earlier ideas in surveying and optics. The rope stretchers of ancient Egypt stretched corded ropes between two points to measure the path which minimized the distance of separation, and Claudius Ptolemy, in his Geographia (Bk 1, Ch 2), emphasized that one must correct for "deviations