The quantum theory of gravitation, effective field theories, and strings: yesterday and today

This paper analyzes the effective field theory perspective on modern physics through the lens of the quantum theory of gravitational interaction. The historical part argues that the search for a theory of quantum gravity stimulated the change in outlook that characterizes the modern approach to the standard model of particle physics and general relativity. We present some landmarks covering a long period, i.e., from the beginning of the 1930s until 1994, when, according to Steven Weinberg, the modern bottom–up approach to general relativity began. Starting from the first attempt to apply the quantum field theory techniques to quantize Einstein’s theory perturbatively, we explore its developments and interaction with the top–down approach encoded by string theory. In the last part of the paper, we focus on this last approach to describe the relationship between our modern understanding of string theory and effective field theory in today’s panorama. To this end, the non-historical part briefly explains the modern concepts of moduli stabilization and Swampland to understand another change in focus that explains the present framework where some string theorists move.