# perturb

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**Turbulence**— In fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and… …112

**Fermi liquid**— is a generic term for a quantum mechanical liquid of fermions that arises under certain physical conditions when the temperature is sufficiently low. The interaction between the particles of the many body system does not need to be small (see e.g …113

**Radial velocity**— is the velocity of an object in the direction of the line of sight (i.e. its speed straight towards you, or away from you). The light of an object with a substantial radial velocity will be subject to Doppler effect, so the frequency of the light …114

**Nebular hypothesis**— Star formation Interstellar medium Molecular cloud …115

**Protoplanet**— Protoplanets are moon sized planets, or larger embryos within protoplanetary discs. They are believed to form out of kilometer sized planetesimals that attract each other gravitationally and collide. According to planet formation theory,… …116

**Near Field Communication**— or NFC, is a short range high frequency wireless communication technology which enables the exchange of data between devices over about a 10 centimetre (around 4 inches) distance.Fact|date=July 2008 The technology is a simple extension of the ISO …117

**French law on secularity and conspicuous religious symbols in schools**— The French law on secularity and conspicuous religious symbols in schools bans wearing conspicuous religious symbols in French public (i.e. government operated) primary and secondary schools. The law is an amendment to the French Code of… …118

**Fluctuation dissipation theorem**— In statistical physics, the fluctuation dissipation theorem is a powerful tool for predicting the non equilibrium behavior of a system such as the irreversible dissipation of energy into heat from its reversible fluctuations in thermal… …119

**Wilkinson's polynomial**— In numerical analysis, Wilkinson s polynomial is a specific polynomial which was used by James H. Wilkinson in 1963 to illustrate a difficulty when finding the root of a polynomial: the location of the roots can be very sensitive to perturbations …120

**Function problem**— In computational complexity theory, a function problem is a problem other than a decision problem, that is, a problem requiring a more complex answer than just YES or NO.Notable examples include the travelling salesman problem, which asks for the …