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:
“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)
“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)
“The peace loving nations must make a concerted effort in opposition to those violations of treaties and those ignorings of humane instincts which today are creating a state of international anarchy and instability from which there is no escape through mere isolation or neutrality.... When an epidemic of physical disease starts to spread, the community approves and joins in a quarantine of the patients in order to protect the health of the community against the spread of the disease.”
—Franklin D. Roosevelt (1882–1945)