Astrophysical plasmas often experience a form of this phenomenon caused by the injection of a hot “stream” of particles. For 10 points each:
[10m] Name this phenomenon in which small perturbations cause a system to rapidly leave equilibrium, which shares its name with a property possessed by the inverted pendulum.
ANSWER: instability [or word forms like unstable; accept two-stream instability]
[10h] The two-stream instability is essentially the inverse of a damping process named for this Soviet physicist, who wrote a Course of Theoretical Physics with Evgeny Lifshitz and ranked the talent of physicists on a log-scale.
ANSWER: Lev Landau [or Lev Davidovich Landau]
[10e] Fluid instabilities occur when a wave’s frequency is one of these numbers, which equal a real number times the square root of negative one.
ANSWER: imaginary numbers [prompt on complex numbers]
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