In the physical sciences, relaxation usually means the return of a perturbed system into equilibrium. Each relaxation process can be characterized by a relaxation time τ. The simplest theoretical description of relaxation as function of time t is an exponential law exp(-t/τ).

Let the homogenous differential equation:

model damped unforced oscillations of a weight on a spring.

The displacement will then be of the form Failed to parse (Missing texvc executable; please see math/README to configure.): y(t) = A e^{-t/T} \cos(\mu t - \delta) . The constant T is called the relaxation time of the system and the constant μ is the quasi-frequency.

In an RC circuit containing a charged capacitor and a resistor, the voltage decays exponentially:

The constant Failed to parse (Missing texvc executable; please see math/README to configure.): \tau = RC\

In condensed matter physics, relaxation is usually studied as a linear response to a small external perturbation. Since the underlying microscopic processes are active even in the absence of external perturbations, one can also study "relaxation in equilibrium" instead of the usual "relaxation into equilibrium" (see fluctuation-dissipation theorem).

Anoushka Shankar (born 9 June 1981) is a British Indian sitar player and composer who lives between the United States, the United Kingdom, and India. She is the daughter of Indian sitar player Ravi Shankar and Sukanya Shankar. She is the paternal half-sister of Norah Jones.

Shankar was born in London and divided her childhood between London and Delhi. As a teenager, she lived in Encinitas, California and attended San Dieguito Academy. A 1999 Honors graduate, Shankar decided to pursue a career in music rather than attend college.

Anoushka married British director Joe Wright. Their first child, Zubin Shankar Wright, was born on 22 February 2011.

Shankar began training on the sitar with her father as a child, and gave her first public performance at the age of thirteen at Siri Fort in New Delhi. By the age of fourteen, she was accompanying her father at concerts around the world, and signed her first record contract, with Angel Records (EMI) at 16.

Though success came at an early age for Shankar, she was still uncertain if music was the career she wanted to fully pursue. "The question was continually back and forth in my mind," she admits. "After I graduated from high school, I made a decision not to go to college and start touring full-time. Even at that time, I thought maybe I’d do it for a year and see what happens. During that year, it became so clear to me that that was my life and who I was– a touring musician."