Predictive power

A classic example of the predictive power of a theory is the discovery of Neptune as a result of predictions made by mathematicians John Couch Adams and Urbain Le Verrier, based on Newton's theory of gravity.

Moreover, Charles Darwin used his knowledge of evolution by natural selection to predict that since a plant (Angraecum sesquipedale) with a long spur in its flowers exists, a complementary animal with a 30 cm proboscis must also exist to feed on and pollinate it.

Twenty years after his death, a form of hawk moth (Xanthopan morganii) that did just that was found.

This was experimentally verified by an expedition to Sobral in Brazil and the Atlantic island of Príncipe to measure star positions during the solar eclipse of May 29, 1919, when observations made by the astrophysicist Arthur Eddington seemed to confirm Einstein's predictions.

Later, more precise measurements taken by radio interferometry confirmed the predictions to a high degree of accuracy.