Yes, and yes. Not "any conceivable" but "any conceivable gravitational observation". The trouble with dark matter is that it's unimodal: It exists to fix a pr

Yes, and yes. Not "any conceivable" but "any conceivable gravitational observation". The trouble with dark matter is that it's unimodal: It exists to fix a problem where our theory of gravity disagrees with observation, but at the same time the only way to measure dark matter is by observing gravitational effects. The only true predictions made have been "if dark matter is actually x particle then ..." Or (weaker) "if dark matter has non-gravitational property X, then..." And thus far all prediction of those sort have been refuted.