Landau's Fermi liquid theory

Landau's Fermi liquid theory describes how electrons behave in metals at low temperatures. Instead of acting like free particles, electrons interact but still move collectively as "quasi-particles" with properties similar to free electrons, such as energy and momentum. These quasi-particles carry electrical current without losing their identity, allowing metals to conduct electricity efficiently. The theory explains why many metals show predictable behaviors despite complex interactions, emphasizing that the system's low-energy excitations resemble those of non-interacting particles, which simplifies understanding their collective behavior in conducting materials.