Invariant (physics)

Invariant (physics)

In mathematics and theoretical physics, an invariant is a property of a system which remains unchanged under some transformation.

The gravitational field of the Sun is invariant under a change of time (from, say, now to tomorrow). It is also invariant under change of angular position.

Examples of invariants include the speed of light under a Lorentz transformation and time under a Galilean transformation. Many such transformations represent shifts between the reference frames of different observers, and so by Noether's theorem invariance under a transformation represents a fundamental conservation law. For example, invariance under translation leads to conservation of momentum, and invariance in time leads to conservation of energy.

Invariants are very important in modern theoretical physics, and many theories are in fact expressed in terms of their symmetries and invariants.

Covariance and contravariance generalize the mathematical properties of invariance in tensor mathematics, and are frequently used in electromagnetism and special relativity and general relativity.

References

*


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Invariant — may have several meanings, among which are:* Invariant (computer science), an expression whose value doesn t change during program execution * In computer science, a type in overriding that is neither covariant nor contravariant * Invariant… …   Wikipedia

  • Invariant mass — The invariant mass, intrinsic mass, proper mass or just mass is a characteristic of the total energy and momentum of an object or a system of objects that is the same in all frames of reference. When the system as a whole is at rest, the… …   Wikipedia

  • Invariant differential operators — appear often in mathematics and theoretical physics. There is no universal definition for them and the meaning of invariance may depend on the context. Usually, an invariant differential operator D is a map from some mathematical objects… …   Wikipedia

  • Physics — (Greek: physis φύσις), in everyday terms, is the science of matter [R. P. Feynman, R. B. Leighton, M. Sands (1963), The Feynman Lectures on Physics , ISBN 0 201 02116 1 Hard cover. p.1 1 Feynman begins with the atomic hypothesis.] and its motion …   Wikipedia

  • Invariant latitude — is a parameter that describes where a particular magnetic field line touches the surface of the Earth. It is given byLambda = arccosleft(sqrt{1/L} ight)orL = 1/cos^2left(Lambda ight)where Lambda is the invariant latitude and L is the L value… …   Wikipedia

  • Invariant De Runge Lenz — Vecteur de Runge Lenz Dans cet article les vecteurs et leurs normes sont indiqués respectivement en gras et italique. Par exemple : . En mécanique classique, le vecteur de Runge Lenz ou invariant de Runge Lenz est un vecteur utilisé… …   Wikipédia en Français

  • Invariant de Runge Lenz — Vecteur de Runge Lenz Dans cet article les vecteurs et leurs normes sont indiqués respectivement en gras et italique. Par exemple : . En mécanique classique, le vecteur de Runge Lenz ou invariant de Runge Lenz est un vecteur utilisé… …   Wikipédia en Français

  • Invariant de runge lenz — Vecteur de Runge Lenz Dans cet article les vecteurs et leurs normes sont indiqués respectivement en gras et italique. Par exemple : . En mécanique classique, le vecteur de Runge Lenz ou invariant de Runge Lenz est un vecteur utilisé… …   Wikipédia en Français

  • Invariant (mathematics) — In mathematics, an invariant is a property of a class of mathematical objects that remains unchanged when transformations of a certain type are applied to the objects. The particular class of objects and type of transformations are usually… …   Wikipedia

  • physics — /fiz iks/, n. (used with a sing. v.) the science that deals with matter, energy, motion, and force. [1580 90; see PHYSIC, ICS] * * * I Science that deals with the structure of matter and the interactions between the fundamental constituents of… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”