The Shadow of Great Britain

Chapter 885: Chapter 14 The Differences between France and Britain

The spring sunshine in Paris was bright, with a gentle breeze stirring the plane tree leaves along the Seine River, creating ripples in the water.

Inside the hall of the French Academy of Sciences, the lights were brilliant, and the golden decorations shimmered alongside solemn marble statues, creating an atmosphere of grandeur.

Backstage, Arthur, who was about to take the stage, was chatting with several eminent figures of the Academy.

Contrary to Arthur’s expectations of a harmonious meeting, the scientists were actually in a heated argument over the letter brought by Faraday.

The focus of the debate was whether light was a particle or a wave.

In the heat of the argument, they naturally recalled the French Academy of Sciences’ annual essay competition of 1819, all remembering the essay title: “Determine the diffraction effects of light through precise experiments and deduce the motion of light when it passes near objects.”

The reason for this essay title was that proponents of the particle theory within the Academy hoped to leverage societal forces to produce papers explaining light interference and diffraction using the particle theory, thus suppressing the wave theory.

Unexpectedly, an unknown engineer, Augustin-Jean Fresnel, seized this opportunity to submit a paper titled “On the Interaction of Polarized Light” to the competition committee.

In this paper, Fresnel revolutionary posited that light is a transverse wave. From this starting point, he rigorously proved the problem of light diffraction and resolved several other longstanding issues troubling the wave theory.

Upon receiving Fresnel’s paper, the head of the competition committee, Poisson, vehemently refused to believe it, considering it utterly absurd.

He even confronted Fresnel directly, saying: “I reviewed your theory and did some calculations. It led to the ridiculous conclusion that if an opaque circular disk is placed in the path of a light beam, diffraction at the disk’s edges would produce a bright spot at the center of the shadow—how is this possible?”

After making this statement, Poisson eagerly declared the particle theory’s victory in the competition.

However, fellow judge Arago proposed: “Wouldn’t it be simple to verify this conclusion by doing an experiment?”

As a result, the French Academy of Sciences immediately conducted an experiment, and the results shocked everyone—Fresnel’s theory was correct, and a bright spot indeed appeared at the center of the shadow.

Following the experiment, perhaps to mock Poisson or give him a way out, the wave theory supporters humorously named the bright spot “Poisson’s spot.”

Fresnel was awarded victory in this competition for his significant discovery and was elected as a member of the French Academy of Sciences.

Poisson also didn’t lose entirely; he was credited as the discoverer of Poisson’s spot, though he wasn’t keen on having this “honor.”

Seeing that even on Poisson’s good day, colleagues couldn’t help but poke fun at his mishap, the Academy’s lifelong secretary in charge of daily affairs, and the Royal Society’s 1825 Copley Medal winner, Arago, hurried to smooth things over.

“Gentlemen, we have argued for many years about the particle theory versus the wave theory, starting with the debate between Newton and Hooke. The Royal Society was in chaos over this matter, and these two great natural philosophers even became adversaries.

In the 19th century, the battlegrounds moved from the Royal Society to France, with Malus and Fresnel on the wave theory side, and Laplace, Poisson, and Biot supporting the particle theory.

Despite the paper being published over a decade ago, we still can’t clearly determine if light is a particle or a wave. Mr. Faraday’s letter simply inquires politely about the nature of waves, so why rush to declare your stance on this issue?”

Arago hoped his words would subdue the tension, but on the contrary, they incited a fierce reaction.

“Mr. Arago, we respect your opinion, but research is no joking matter.”

“Exactly, from Mr. Faraday’s letter, it’s clear that he seeks to discover the connection between light and magnetism. If he misunderstands the nature of light from the start, wouldn’t we be leading him astray?”

“This could cause years or decades of stagnation in this direction, with Mr. Faraday wasting considerable time on fruitless efforts. This not only tarnishes the Academy’s reputation, but from a research perspective, it’s unforgivable!”

Watching the gentlemanly scientists surround Arago like lions, Arthur felt sympathy for the lifelong secretary but also some relief.

Since as he knew, Arago had already shifted to studying electromagnetism after being inspired by Oersted in 1820.