In numerous fields of study, the component of **instability** within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be marginally stable or exhibit limit cycle behavior.

In control theory, a system is unstable if any of the roots of its characteristic equation has real part greater than zero (or if zero is a repeated root). This is equivalent to any of the eigenvalues of the state matrix having either real part greater than zero, or, for the eigenvalues on the imaginary axis, the algebraic multiplicity being larger than the geometric multiplicity.

In structural engineering, a structure can become unstable when excessive load is applied. Beyond a certain threshold, structural deflections magnify stresses, which in turn increases deflections. This can take the form of buckling or crippling. The general field of study is called structural stability.

Atmospheric instability is a major component of all weather systems on Earth.

Read more about Instability: Fluid Instabilities, Plasma Instabilities, Instabilities of Stellar Systems

### Other articles related to "instability":

**Instability**- Instabilities of Stellar Systems

... After the

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**Instability**

... The Omani invasion began a period of political

**instability**and a quick succession of outside rulers took power with consequent destruction ... The years of almost constant warfare and

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**Instability**

... higher dimensions are found to exhibit an

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...

**Instability**Field Person(s) Named After Bénard

**instability**Natural convection, Rayleigh–Bénard convection Henri Bénard Benjamin–Feir

**instability**Surface gravity waves T ... Feir Buneman

**instability**Plasma physics Oscar Buneman Cherenkov

**instability**Plasma physics Pavel Alekseevič Čerenkov Chromo-Weibel

**instability**Plasma ... Weibel Crow

**instability**Aerodynamics S ...

### Famous quotes containing the word instability:

“With one more talent one frequently stands with greater *instability* than with one less, as a table stands better on three legs than on four.”

—Friedrich Nietzsche (1844–1900)

“The difference between tragedy and comedy is the difference between experience and intuition. In the experience we strive against every condition of our animal life: against death, against the frustration of ambition, against the *instability* of human love. In the intuition we trust the arduous eccentricities we’re born to, and see the oddness of a creature who has never got acclimatized to being created.”

—Christopher Fry (b. 1907)

“What exacerbates the strain in the working class is the absence of money to pay for services they need, economic insecurity, poor daycare, and lack of dignity and boredom in each partner’s job. What exacerbates it in upper-middle class is the *instability* of paid help and the enormous demands of the career system in which both partners become willing believers. But the tug between traditional and egalitarian models of marriage runs from top to bottom of the class ladder.”

—Arlie Hochschild (20th century)