|Urbain Le Verrier|
Science studies facts and tries to explain why they occur. Scientific theories are the more credible, the more facts they explain or predict. A single fact in opposition to a theory, or a single unconfirmed prediction, is enough to make us consider revising the theory. With the scientific method, theories are never final and facts must always take precedence.
We have a classic historical example in the theory of universal gravitation, which allowed Newton to explain events like the fall of bodies and the movement of planets and satellites. Its first achievement, by Newton himself, was the mathematical deduction of Kepler’s three experimental laws, obtained empirically from the observation of the orbits of the planets. But the greatest success of the theory was a correct prediction when discrepancies were detected between the orbit of Uranus deduced from the theory and the observed orbit. When something like this happens, the problem can be solved in two ways: