I not understand what you mean by this. We always had those. Do you believe in the existence of: - computers solving the generic halting problem - perpetual m

I not understand what you mean by this. We always had those. Do you believe in the existence of: - computers solving the generic halting problem - perpetual motion devices - faster than light communication I guess no, because based upon our current knowledge of physical/logical laws these are nonexistent (impossible) things. And there are many existence proof with the same confidence level. So science have both positive and negative proofs (actually verification is a better term) with similar confidence.