The response function of the infinite nuclear matter

The paper is an attempt for a detailed understanding of the spectrum of an infinite Fermi system (in particular nuclear matter). Essentially it revisits well known topics even though an attempt is made to present them in a somewhat more unified way and a few new elements on the energy behaviour of the total Coulomb cross-section and on the RPA treatment of the Bose-type collective motion in an infinite Fermi system. The technique utilized is the quantum field theory: neutrons and protons appear as field quanta. Questions connected with the superfluidity (superconductivity) of infinite nuclear matter are not considered