Editing Fermi liquid theory (section)

==Similarities to Fermi gas==
The Fermi liquid is qualitatively analogous to the non-interacting [[Fermi gas]], in the following sense: The system's dynamics and thermodynamics at low excitation energies and temperatures may be described by substituting the non-interacting fermions with interacting [[quasiparticle]]s, each of which carries the same [[Spin (physics)|spin]], [[Electric charge|charge]] and [[momentum]] as the original particles. Physically these may be thought of as being particles whose motion is disturbed by the surrounding particles and which themselves perturb the particles in their vicinity. Each many-particle excited state of the interacting system may be described by  listing all occupied momentum states, just as in the non-interacting system. As a consequence, quantities such as the heat capacity of the Fermi liquid behave qualitatively in the same way as in the Fermi gas (e.g. the heat capacity rises linearly with temperature).