well we don't search for proof, really. scientific theories can't be proven, only supported or rejected. no matter how plentiful and consistent the experimental support might be, new evidence might someday arise to show a theory's not quite right. Newton's 'law' of gravity was accepted as precisely correct for hundreds of years until Einstein said 'Hold up, now.'
scientific theories never become fact. a theory may be exactly right, which is very unlikely in any case, but we can never know it. carry on.