We hear the phrase settled science so much these days. The same sentiment was heard in the late 1890s concerning Physics when teachers were discouraging students from pursuing the subject. Did they revise their opinion when Special Relativity came along? Or later when General Relativity appeared? No!
It's probably always tempting for some to claim that a subject can now be closed. In the brilliant book “Zen and the art of motorcycle maintenance”, Robert Pirsig describes the real scientific method, which consists of the formulation of hypotheses followed by experimental tests. He also indicates that scientific principles often have a short lifespan before they get replaced by a new one.
The idea of settled science is meaningless. It exists only in the minds of scientists like those one in the 1890s who proclaimed that Physics was settled.