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Theoretical Physics 
The advancement of Science depends, in general, on the interplay between experiments and theory. Theoretical physics is that field of physics which employs mathematical models and, more recently, also numerical tools, in the attempt to rationalize, explain and predict natural phenomena.
The roots of Theoretical physics can be found in the Greek philosophy, when the concepts of matter, energy, space, time and causality slowly began to acquire the form we know today, together with the belief that nature could be described through mathematical symbolism. But the modern era of theory starts several centuries later, in the early 1600, with the Copernican paradigm shift in astronomy, soon followed by Johannes Kepler's expressions for planetary orbits, which summarized the meticulous observations of Tycho Brahe.
Simultaneously, the great physical intuitions of Galileo and the analytic geometry of Descartes were incorporated into the classical mechanics of Isaac Newton, extended in the 18th century by JosephLouis Lagrange, Leonhard Euler and William Rowan Hamilton, with which the interactive intertwining of mathematics and physics begun two millennia earlier by Pythagoras definitively triumphs.
The 19th century saw the consolidation of the idea of energy by the inclusion of heat, then electricity and magnetism and light, and finally mass. In this context the laws of thermodynamics, and especially the introduction of the singular concept of entropy, began to provide a macroscopic explanation for the properties of matter, whose theoretical framework was provided by the statistical mechanics of Boltzmann and Gibbs, which relates the microscopic properties of individual atoms and molecules to the macroscopic or bulk properties of materials that can be observed in everyday life, therefore explaining thermodynamics as a natural result of statistics and mechanics at the microscopic level.
But the pillars of modern theoretical physics, and perhaps the most revolutionary theories in the history of physics, were built in the early 20th century: on one hand Newtonian mechanics was subsumed under Einstein’s special relativity and Newton's gravity was given a kinematic explanation by general relativity; on the other hand, quantum mechanics led to an understanding of blackbody radiation and of anomalies in the specific heats of solids and finally to an understanding of the internal structures of atoms and molecules.
Nowadays theoretical physicists work to unify theories and explain phenomena in further attempts to definitively understand the Universe, from the cosmological to the elementary particle scale (e.g. Inflation Cosmology, Standard Model, Quantum Field theory, QCD, Superfluidity, Quantum Information, etc.), through the mesoscopic level represented by the condensed matter physics (e.g. Solid Mechanics, Fluid Dynamics, Electronic structure of materials, Chaos and Complexity theories, Complex Networks, etc.), up to the more recent application of physical models to apparently far fields, such as biology, economics, sociology and so on (e.g. Biophysics, Econophysics, Sociophysics, etc.).

Last Updated on Monday, 28 December 2009 17:29 
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