The minimum critical mass

For your idea to spread, your app to go viral, your restaurant to be the place, it's likely you'll need to hit critical mass.

This is a term from physics, describing the amount of plutonium you need in a certain amount of space before a reaction goes out of control, leading to a meltdown or explosion. In this case, though, it's a positive thing.

Once enough people start driving your new brand of motorcycle around town, it's seen by enough people that it becomes accepted, and sales take off from there.

Once enough people who know enough people start talking about your new app, the touchpoints multiply and organic growth kicks in.