yes, that's what I meant; thanksunusualname said:you need to impose a discretization condition
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edit: you may have meant this by "bose gas" ...
Planck's law is a fundamental equation in physics that describes the distribution of energy emitted by a blackbody at a given temperature. It was derived by German physicist Max Planck in 1900 using assumptions about the quantization of energy.
The main assumptions used in the derivation of Planck's law are the existence of discrete energy levels in a system and the principle of equipartition of energy, which states that energy is distributed equally among all available degrees of freedom.
Planck's law can be applied to any object that absorbs and emits radiation at all wavelengths, not just blackbodies. However, it is most accurate for objects that behave like ideal blackbodies, which absorb and emit all radiation that falls on them and have a constant emissivity at all wavelengths.
Planck's law is derived under the assumption of thermal equilibrium, but it can still be used to describe the radiation emitted by a body even if it is not in thermal equilibrium. However, the resulting spectral distribution may not follow the exact shape predicted by Planck's law.
Planck's law is closely related to other fundamental laws and principles in physics, including the laws of thermodynamics, the principle of conservation of energy, and the wave-particle duality of light. It also forms the basis for other important equations, such as the Stefan-Boltzmann law and Wien's displacement law.