Abstract
Physics is an experimental science, and the discovery of the Wave window arose from a paradigm shift in the demonstration of Planck's law. One focuses on power measurements of the radiation passing through the surface of the black body cavity wall. It is generally given by a spectroradiometer with a fixed bandwidth. However, when Planck imagines the hypothetical resonator to represent the energy of a perfect gas molecule and uses Boltzmann's combinatorial-probabilistic treatment with entropy, the dimensional analysis of Planck's law directly provides a physical object to represent the energy of this molecule. Indeed, one sees that the law is the product of the number of surface elements of a wavelength squared per unit area and the power of an element. Therefore, one names this surface element a "Wave window" and uses its energy flux in a similar way to the energy of a perfect gas molecule, instead of the resonator. The demonstration of Planck's law is thus simplified, and the enigma of the Planck resonator is solved. Furthermore, one uses a derivation of the blackbody radiation law from the Stefan-Boltzmann law, employing a Riemann sum instead of the usual definite integral. This updates the law to account for bandwidth.