The only way to know if somebody was really an expert is to look back in 100 years time and see if what they said really worked and stood the test of time.
and in 101 years we learn something new and the "expert" is revealed for what he is ... nearly right.
Newton's equations of motion are astonishingly successful ... using them we can predict the motion of a spacecraft and orchestrate a slingshot manoeuvre around a distant planet.
Yet, Einstein had a better set of equations, created a new understanding and allowed us to make further advances.
another day in paradise, or is paradise one day closer ?