Quantum mechanics arose from Planck's solution, published in 1900, to the black-body radiation problem.
=== Kirchhoff's perfect black bodies ===Kirchhoff in 1860 introduced the theoretical concept of a perfect black body with a completely absorbing surface layer of infinitely small thickness, but Planck noted some severe restrictions upon this idea
 In 1935, Einstein and his collaborators Boris Podolsky and Nathan Rosen published an argument that the principle of locality implies the incompleteness of quantum mechanics, a thought experiment later termed the EinsteinPodolskyRosen paradox

