I am looking to understand the impact of finite temperature quantum field theory. specifically low energy version applied to condensed matter. Certainly it helps to treat many-body systems a fundamentally as possible, however under finite temperature most of these quantum effects are negligible or can be treated without field theory.
I am looking the historical context of formalisms like that of Matsubara, Keldysh and KMS. I think these concepts has become much more settled now than a few decades ago. Here is a picture of a wall in the Warsaw University's Centre of New Technologies where the KMS condition is engraved as one of the main equations of science.
Were there historical problems in condensed matter that needed to be fully treated under a quantum field version? How these different versions developed? Where them inspired from relativistic quantum field theory first? Any general account of the matter would be helpful.