journal club on aspects of information, quantum theory, and gravity
05 Sep 2024
The major problem in quantum gravity tends to be seen as the difficulty in obtaining an ultraviolet completion of general relativity. Pure general relativity is a non-renormalizable theory, and therefore loses its predictability on scales close to the Planck scale. Interestingly, however, adding quadratic terms in the curvatures to the action of gravity makes the theory perturbatively renormalizable, a fact known at least since the 1970s (and suspected since the 1960s). In this series of lectures, I intend to revisit general concepts of renormalization in curved spacetimes (in the case of both QFTCS and general relativity) and argue that quadratic terms are to be expected in a quantum theory of gravity. Having done so, I will discuss the advantages, disadvantages, and my criticisms of the quadratic gravity program.