theoretical physics

Also found in: Acronyms, Wikipedia.

Theoretical physics

The description of natural phenomena in mathematical form. It is impossible to separate theoretical physics from experimental physics, since a complete understanding of nature can be obtained only by the application of both theory and experiment. There are two main purposes of theoretical physics: the discovery of the fundamental laws of nature and the derivation of conclusions from these fundamental laws.

Physicists aim to reduce the number of laws to a minimum to have as far as possible a unified theory. When the laws are known, it is possible from any given initial conditions of a physical system to derive the subsequent events in the system. Sometimes, especially in quantum theory, only the probability of various events can be predicted. See Determinism, Quantum mechanics

The conclusions to be derived from the fundamental laws of nature may be of several different types.

1. Conclusions may be derived in order to test a given theory, particularly a new theory. An example is the derivation of the spectrum of the hydrogen atom from quantum mechanics; the verification of the predictions by accurate measurements is a good test of quantum mechanics. On rather rare occasions an experiment has been found to contradict the predictions of an existing theory, and this has then led to the discovery of important new physical laws. An example is the Michelson-Morley experiment on the constancy of the velocity of light, an experiment which led to special relativity theory. See Atomic structure and spectra, Light, Relativity

2. Theory may be required for experiments designed to determine physical constants. Most fundamental physical constants cannot be accurately measured directly. Elaborate theories may be required to deduce the constant from indirect experiments. See Fundamental constants

3. Predictions of physical phenomena may be made in order to gain understanding of the structure of the physical world. In this category fall theories of the structure of the atom leading to an understanding of the periodic system of elements, or of the structure of the nucleus in which various models are tested (for example, shell model or collective model). In the same category fall applications of theoretical physics to other sciences, for example, to chemistry (theory of the chemical bond and of the rate of chemical reactions), astronomy (theory of planetary motion, internal constitution, and energy production of stars), or biology.

4. Engineering applications may be drawn from fundamental laws. All of engineering may be considered an application of physics, and much of it is an application of mathematical physics, such as elasticity theory, aerodynamics, electricity, and magnetism. The generation and propagation of radio waves of all frequencies are examples of application of theoretical physics to direct practice. See Aerodynamics, Electricity, Magnetism

Apart from the classification of the fields of theoretical physics according to purpose, a classification can also be made according to content. Here one may perhaps distinguish three classification principles: type of force, scale of physical phenomena, and type of phenomena. See Mathematical physics, Physics

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

theoretical physics

[‚thē·ə′red·ə·kəl ′fiz·iks]
The description of natural phenomena in mathematical form.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
"I am now convinced that theoretical physics is actually philosophy."
"We are very excited to partner with Perimeter Institute for Theoretical Physics, one of the leading centers for research, training, and educational outreach in theoretical physics.
"What we perceive as three dimensional may just be the image of two dimensional processes on a huge cosmic horizon," say researchers at the University of Vienna, who have applied the holographic principle from theoretical physics to our flat spacetime.
In October 2004 the Perimeter Institute for Theoretical Physics opened its doors in Waterloo, Ont.
Sir Peter, who graduated from Durham in 1968 with a degree in physics and a PhD in theoretical physics in 1971, lends his name to the original Ogden Centre for Fundamental Physics which opened in 2002, thanks to an earlier PS2m gift from The Ogden Trust.
PLANS: Study theoretical physics at Stanford or Harvard.
He is also a member of the Landau Institute for Theoretical Physics at the Russian Academy of Sciences.
In this case it partnered with the Institute for Electronics, Microelectronics, and Nanotechnology (IEMN) in Lille, France, the Debye Institute for Nanomaterials Science and the Institute for Theoretical Physics of the University of Utrecht, Netherlands and the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany.
Witty, combining personal anecdote with hard science, this is both a wonderful introduction into the endlessly fascinating world of theoretical physics and a personal story of two of its most prominent practitioners' involvement in the ground-breaking discoveries attending it.
Physical chemistry is to general chemistry as theoretical physics is to general physics.
Her replacement has been confirmed as Dr Charles Wall, who has a PhD in theoretical physics and has worked in the UK, Cairo, Singapore and Zimbabwe.
This is a spectacular effort to make the real stuff of theoretical physics accessible to amateurs.

Full browser ?