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  François Arago addressed criticism #5823.

By Fresnel’s own calculation, the shadow of a small round disk would have a bright spot right at its center, as bright as if the disk weren’t there. That’s absurd.

#5823​·​Siméon Denis PoissonHistorical profile, March 15, 1819​·​AI-assisted

I put a small round disk in a narrow beam of light, and the bright spot is there, at the center of its shadow, just as Fresnel’s theory says.