Yes, critical mass is a physics term, referring to the the 'minimum amount of fissile material needed to maintain a nuclear chain reaction'. But the second definition is a great basis for a story.
The second definition of critical mass is the 'minimum size or amount of something required to start or maintain a venture.' Whenever I hear this, I think of some politician trying to get his or her audience and network of support in place to run for office. Bring on the scriptwriters!
There's also a strain of Critical Mass
“Critical mass is the minimum size needed to start a venture.”