Lecture
This lecture discusses the difference between non-perturbative and perturbative effects in quantum physics, focusing on instantons in the double well potential. The slides cover the limitations of perturbation theory in capturing important effects, such as metastable states and tunneling phenomena. The lecture also explores the exact eigenstates in the double well potential and the concept of instantons in the Euclidean propagator. Emphasis is placed on the significance of non-perturbative effects and their implications in understanding quantum phenomena.