All of us ordinary folks, even those with little or no technical expertise, have theories. These theories are the way that we try to comprehend our world. Some are explicit and some implicit. Cognitive scientists call these folk theories
I wouldn't underestimate folks, as many folks have more time for their private research, then the full-time scientists payed from taxes. They differ in their ability to spread theory via official journal channels.
When folk theory meets scientific theory?
When it becomes falsifiable, i.e. testable by experiments. In addition, proponents of formal sciences, like physics require, new theory must by formalized first in math language before it can be presented as a scientific theory. Of course, it doesn't mean, such theory becomes more true/false or even comprehensible, after then.
