That makes my brain hurt.
It's a phenomenon known in the technical sense as stability. The wikipedia page is for stability theory, but if you're not familiar with differential equations, the wiki isn't very helpful. Essentially, what stability theory says is that a system is stable if when it's perturbed just a little bit, the perturbation tends to decay with time. Or the corollary, a system is unstable if small perturbations tend to grown with time. The interesting part is that this physical theory applies to society (although some might argue that saying that is a bit tautological). Social change is not possible with just a few people perturbing the system; a critical amount of energy is needed to reach a new stability, just like in physics.