_____________________ What is Physics ?

Physics is often described as the study of matter and energy. It is concerned with how matter and energy relate to each other, and how they affect each other over time and through space. Physicists ask the fundamental questions how did the universe begin? how and of what is it made? how does it change? what rules govern its behavior?

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's model 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

Astrophysics

"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 Atomic Scale" by Jacqueline Krim, October 1996

Biophysics and Medical Physics

"Advances in Tumor Imaging" by Maryellen L. Giger and Charles A. Pelizzari, September 1996

"The Machinery of Thought" by Tim Beardsley, August 1997

Solid State Physics

"Ion Implantation of Surfaces" by S.T. Picraux and P.S. Peercy, March 1985

"Crystals at High Pressure" by R.M. Hazen and L.W. Finger, May 1985

"Advanced Metals" by B.H. Kear, October 1986

"Quantum Dots" by M.A. Reed, January 1993

"High-Temperature Superconductors" by P.C.W. Chu, September 1995

"Electrons in Flatland" by Steven Kivelson, Dung-Hai Lee and Shou-Cheng Zhang, March 1996

"Probing High-Temperature Superconductivity" by John R. Kirtley and Chang C. Tsuei, August 1996

Optical and Laser Physics

"Laser Applications in Manufacturing" A.V.La Rocca, March 1982

"Optical Gyroscopes" by D.Z. Anderson, April 1986

"X-Ray Microscopes" by M.R. Howells, J. Kirz and D. Sayre, February 1991

"Liquid Mirrors" by Ermanno F. Borra, February 1994

"Quantum Seeing in the Dark" by P. Kwiat, H. Weinfurter and A. Zeilinger, November 1996

"Lightning Control with Lasers" by Jean-Claude Diels, Ralph Bernstein, Karl E. Stahlkopf and Xin Miao Zhao, August 1997

Fluid and Plasma Physics

"The Active Solar Corona" by R.Wolfson, February 1983

"The Structure of Comet Tails" by J.C.Brandt and M.B.Niedner, January 1986

"The Earth Magnetotail" by E.W.Hones, March 1986

"The 3He Superfluids" by O.V. Lounasmaa and G. Pickett, June 1990

"The International Thermonuclear Experimental Reactor" by R.W. Cohn, V.A. Chuyanov, N. Inoue and D.R. Sweetman, April 1992

"Tackling Turbulence with Supercomputers" by Parviz Moin and John Kim, January 1997

Nuclear Physics

"Hot Nuclear Matter" by W. Greiner and H. Stoecker, January 1985

"Radiocarbon Dating by Accelerator Mass Spectroscopy" by R.E.M. Hedges and J.A.J. Gowlett, January 1986

"Rethinking Nuclear Power" by R.L.Lester, March 1986

"Exotic Atomic Nuclei" by J.H. Hamilton and J.A. Maruhn, July 1986

"Creating Superheavy Elements" by P. Armbruster and G. Muenzenberg, May 1989

"Halo Nuclei" by Sam M. Austin and George F. Bertsch, June 1995

"Fusion" by Harold P. Furth, September 1996