Ask HN: What's the difference between a theory and a fact?
Can a theory ever become a fact? Or are they in two completely different areas, so one can never become the other?
For example, was gravity ever a theory (assuming it's a fact now)?
For example, was gravity ever a theory (assuming it's a fact now)?
Theories are abstract and conceptual, and they are never known to be correct or incorrect. Rather, we build a corpus of evidence for or against them -- we never know their validity 100% for sure. For example, at any point in the future, we may find some piece of evidence which disproves gravity as we know it. Then, we will be forced to revise our theory of gravitation (e.g. when general relativity was discovered).
A fact is something that is 100% true. If I say that "Sacramento is the capital city of California," then this is a fact because we defined it that way.
It could be that the theory of gravitation is 100% true and hence a fact. However, we will never know this, so to us it will always be a theory. Sometimes, people feel so sure about a theory that they go ahead and call it a "fact" or a "law" -- but this just indicates that a lot of evidence supports it and hopefully no evidence (yet) invalidates it; it is still a theory. (So to be precise, my original "fact" about dropping something is really a theory with LOTS of evidence!)
So to answer your question, a theory can be correct or incorrect. If it is correct, then it is also a fact. However, we will never know 100% whether it is correct, so to be precise we should continue to call it a theory.
As I understand it, a theory is any hypothesis that is believed to hold (at least for now, under the conditions it's thus far tested under, or based on the evidence we already have). In other words, a theory is a hypothesis that is provisionally considered true.
Thus, my hypothesis about your back garden could turn into a general theory of conditions under which gravity turned negative, if observations were made which supported it (which is, admittedly, unlikely!).
I'd agree with the Sacramento example above, i.e. that the only things we can consider facts are things that we've agreed upon/defined. This is a smaller set of things than people normally call facts.
As a starting point, I can recommend you check out lesswrong.com, you can find their "introductory reading" here: http://wiki.lesswrong.com/wiki/Sequences the first item on the list deals exactly with the question you have posed:
http://yudkowsky.net/rational/the-simple-truth
Happy reading!
How a theory can come to be (or needs to be) "proven" to become a fact is more of a philosophical question than anything else, and if the schism between religion and atheism is any indication, it's a contentious one that I generally prefer to stay away from arguing.