“He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may cast.” -Leonardo Da Vinci
For centuries, Newton’s theoretical predictions were as unassailable as physics got. His ideas about mechanics, gravitation and optics passed test after test after test. Yet around the dawn of the 19th century, one class of observations appeared to run counter to his assertions: light appeared to exhibit a wave-like nature. The phenomena of diffraction and interference could not be well-explained by a corpuscular theory of light.
The wave-like nature of light passed through two slits, as illustrated by Thomas Young’s original work, dating from 1803. Image credit: Wikimedia Commons user Quatar.
Towering scientific figures such as Fresnel, Fraunhofer and Poisson calculated what they expected from a wave-like theory under various conditions, with Poisson getting the most absurd result. In theory, light that was shined around a spherical obstacle should produce a shadow… with a brilliant bright spot at the center. This was ruled a victory by Newton for all, proving the wave nature of light’s absurdity.
A theoretical prediction of what the wave-like pattern of light would look like around a spherical, opaque object. The bright spot in the middle was the absurdity that led many to discount the wave theory. Image credit: Robert Vanderbei.
Fools! For you cannot simply claim an absurdity without doing the experiment to check! The results, the lessons, and the work of Francois Arago must never be forgotten.