Phonons and Forces: Momentum versus Pseudomomentum in Moving Fluids
arXiv:cond-mat/0012316
Abstract
I provide a pedagogical introduction to the notion of pseudomomentum for waves in a medium, and show how changes in pseudomomentum may sometimes be used to compute real forces. I then explain how these ideas apply to sound waves in a fluid. When the background fluid is in motion, the conservation laws for pseudomomentum and pseudoenergy are most easily obtained by exploiting the acoustic metric and the formalism of general relativity.
This is an expanded version of a talk with the same title that was given at the workshop "Analog models of General Relativity". The workshop took place at CBPF (Centro Brasileiro de Pesquisas F{Ã}sicas), the Brazilian Center for Research in Physics, located in Urca, Rio de Janeiro from 16 to 20th October 2000