Physics and Branches

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Physics is the systematic and scientific study of the way objects , matter and energy moves, changes and interacts. It is really concerned with how fast things move, when they move and what causes things to move.  Those things can be the very large like stars or galaxies or the very small, groups of objects or single objects. It is also about what makes up the fundamental building blocks of the reality we live in . The word physics comes from the Greek word phusika, from neuter pl. of phusikos, meaning "of nature." Physicists may be roughly divided into two camps: experimental physicists and theoretical physicists. Experimental physicists design and run careful investigations on a broad range of phenomena in nature, often under conditions which are atypical of our everyday lives. They may, for example, investigate what happens to the electrical properties of materials at temperatures very near absolute zero (460 degrees Fahrenheit) or measure the characteristics of energy emitted by very hot gases. Theoretical physicists propose and develop models and theories to explain mathematically the results of experimental observations. Experiment and theory therefore have a broad overlap. Accordingly, an experimental physicist remains keenly aware of the current theoretical work in his or her field, while the theoretical physicist must know the experimenter's results and the context in which the results need be interpreted. It is also useful to distinguish classical physics and modern physics. Classical physics has its origins approximately four hundred years ago in the studies of Galileo and Newton on mechanics, and similarly, in the work of Ampere, Faraday,Maxwell and Oersted one hundred fifty years ago in the fields of electricity and magnetism. This physics handles objects which are neither too large nor too small, which move at relatively slow speeds (at least compared to the speed of light: 186,000 miles per second!).  The emergence of modern physics at the beginning of the twentieth century was marked by three achievements. The first, in 1905, was Einstein's brilliant model of light as a stream of particles (photons). The second, which followed a few months later, was his revolutionary theory of relativity which described objects moving at speeds close to the speed of light. The third breakthrough came in 1910 with Rutherford's discovery of the nucleus of the atom.Rutherford's work was followed by Bohr'smodel of the atom, which in turn stimulated the work of de Broglie, Heisenberg, Schroedinger, Born, Pauli, Dirac and others on the quantum theory. The avalanche of exciting discoveries in modern physics continues today. Given these distinctions within the field of physics experimental and theoretical, classical and modern it is useful to further subdivide physics into various disciplines, including astrophysics, atomic and molecular physics, biophysics, solid state physics, optical and laser physics, fluid and plasma physics, nuclear physics, and particle physics. Below you can find references to recent representative articles from Scientific American on major branches of physics. These articles detail specific examples of current research in each particular field. Besides Scientific American, other sources for general articles on current research in physics include Discover magazine and the Science Times section of each Tuesday's New York Times.

Scientific American articles
"Collapse and Formation of Stars" by A.P. Boss, January 1985 "The Great Supernova of 1987" by S. Woosley and T. Weaver, August 1989 "Black Holes in Galactic Centers" by M.J. Rees, November 1990 "The Expansion Rate and Size of the Universe" by W.L. Freedman, November 1992 "The Ghostliest Galaxies" by Gregory D. Bothun, February 1997 Atomic and Molecular Physics

"Detecting Individual Atoms and Molecules with Lasers" by V.S. Letokhov, September 1988 "The Birth of Molecules" by A.H. Zewail, December 1990
"Friction at the...
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