I have a few problems with Poissons's proposed experiment, according to the article cited above.
http://io9.com/5707749/poissons-spot--the-greatest-burn-in-physics"Poisson reasoned that
if light really was a wave, then when a light was turned on a perfectly spherical object, the light waves would bend around the sides of that object. The perfect symmetry of a sphere meant that all the light waves would meet in the exact center of the shadow behind it. There,
people would be able to see a BRIGHT spot of light."
So Poisson's proposal was that if light were a wave, there would be a BRIGHT SPOT on the shadow.
"Dominique Arago ... realized that Poisson had described the perfect experiment. He found a round object, he found a light, and pretty soon, he found a spot. It was right were Poisson said it would be."
However, if you look up articles and MIT videos of Poisson's spot, you see that the spot in the shadow is a DARK SPOT, not a bright spot, as Poissons said would be the case if light is a wave.
In my view, Poisson's rivals changed the wording of Poisson's claim from "a light spot," to "a dark spot," and then claimed that Poisson had proven them right.
The second issue I have is that not one single demonstration of 'Poisson's spot' uses a regular light—again, not one single demonstration. The problems with this are: a) lasers were not in existence during the time of Poisson's experiment; b) laser beams are concentrated (very narrow) wavelengths, which physical characteristics are entirely different than that of sunlight and incandescent light (which shines outward in all directions and is not concentrated and directed), which is closer to the light in all natural light sources; c) whenever Poisson's spot is demonstrated a sphere of roughly the same size as the laser beam is used—they
never experiment on different ratios of light width to sphere width.
http://www.differencebetween.com/difference-between-laser-and-vs-light/This controlled experiment only proves what happens in a controlled (unnatural) environment when the light is concentrated, narrowed, and directed, and when the sphere is the same size as the width as the light. This does not conclusively lay down laws on how all light operates, because unnatural light is used, and no one ever discusses what happens when a natural light shines on different size spheres.
But mostly, Poisson's claim was that a BRIGHT spot would occur if light is a wave, and his opponents changed his words by proving that a DARK spot occurred.
I call dirty pool on this one, and the experiment needs to be done over with natural light and larger spheres. As with all experiments, a variety of test subjects must be used to make the results conclusive, and in this case the test subjects are: the kind of light (wavelength); the brightness of the light; the width of the light source; the diameter of the sphere; the distance from light source to sphere — all of these must be tested to the full spectrum in order to learn anything — no wonder man still does't fully understand light and shadow — having had our perception muddied with dishonesty just so someone could say "I'm right and you're wrong" — our concepts of light/shadow is based on
a few individual people's self-centeredness, self-serving, and self-righteousness attitude.
What the experiment does prove is that light does not cast a bright spot on on the shadow as would occur if light were a wave - and it proves that a shadow is projected onto the surface if the light source is very close to the same size as the sphere—but a shadow is what people expect to see, so nothing new is learned by the experiment, as is.
Just as a side note and comparison, the same strategy of word manipulation and twisting was implemented in the case against Michael Behe's claims of intelligent design. Behe observed that both simple and complex systems could not operate if a piece of its machinery was removed. His opponents changed the wording to argue that pieces could be borrowed from already existing structures. But this did not in any way whatsoever answer the question of what happens to a machine when a piece is removed—in fact it was never discussed what happened to the machine the piece was taken from, if that machine could continue to operate. The case was won by playing dirty pool and twisting Behe's words to mean what he had not said. In addition, the leading scientists against Behe admits in a seminar (posted on YouTube) to his students, that his colleagues were joking with the judge long before the case had been concluded, that they would have to discuss the matter if irreducible complexity again the next day. The scientist recalls to his students how they and the judge all laughed and joked about it. This was not an unbiass judge, this judge was already from the home-team. It was a kangaroo court. But the point in this is that twisting people's words in order to win arguments is not an old trick—and it should not be mistaken as victory, but as fraud and manipulation, and dirty-pool played by people who can not win arguments with honesty and candor.
The real reason the trial was held against Behe was that one of the most infamous atheists and proponents for evolution, Antony Flew, had been won over to intelligent design by Behe's book "Darwin's Black Box." Enemies of God could not allow others to be persuaded by the half-conversion of such a great man, who had such clout and respect. Hence the trials were held in order to "debunk" intelligent design in the minds of would-be believers in a deity. Rather interesting to note here is that Richard Dawkins admitted when talking about Flew that although he feels that Flew was foolish and misled for being won over to creation by I.D., Dawkins followed the statement by stating that Flew would have been justified if he had been won over by the The Cosmological Constant—so by recommendation of Richard Dawkins, you unbelievers should head over and examine The Cosmological Constant. The cosmological constant is such a powerful argument in evidence of a creator that it has led scientists in recent years to conclude that our entire existence is just an illusion, or someone's dream. Again God pushes science into a corner leaving them no room but to conclude and teach that "we don't exist." Rather than admit that God exist, they would rather dismiss all things, including themselves. Well, they'll eventually get their wish by being made not to exist—but they won't change what already does—and their place in the stream of time will be puny and without accounting when they and their philosophies have long gone off into oblivion.
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