Maybe it would help if you explained why you're asking these questions.
I want to know what evidence is. I used to think I knew, but I do not. Is it stuff? A process? A human construct? An amalgamation of the forces of Logic, Reason, and Reality? How will I know it when I see it? Will I see it? Can it exist in a vacuum?
I could go on asking and asking whether it's [insert conceivable description here] or [insert some other conceivable description here], but I think it would be better if I just fessed up and said this is an open-ended question by intent. I have no answers for it, but would like to see if the fine folk here do. Often said is it 'support your assertion with evidence', but does that even mean anything? Who decides what is supporting evidence and what is not? How do they decide it? Is it. Oops; there I go with the questions.
Does this clarify?
Jon
[O]ur tiny half-kilogram rock just compeltely fucked up our starship. - Rahvin