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
Famous quotes containing the word instability:
“Not only does the wind of accidents stir me according to its blowing, but I am also stirred and troubled by the instability of my attitude.”
—Michel de Montaigne (1533–1592)
“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)
“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)