Critical mass comes from physics and is the amount of fissile material necessary to sustain a nuclear chain reaction. As a Mental Models, it can be generalized to the required amount of a thing to generate the desired result1. A similar concept occurs in nueral communication where the membrane of a nerve requires reaching the “Action Potential” threshold in depolarization in order to communicate the message on to the next nerve cell.

1. Weinberg, G. & McCann, L. Super Thinking: The Big Book of Mental Models. (Portfolio, 2019).