How does Planck’s radiation law describe radiation from a heated object?

Planck’s radiation law, formulated by German physicist Max Planck in 1900, describes the spectral-energy distribution of radiation emitted by a blackbody—a theoretical object that perfectly absorbs and re-emits all radiant energy.12

To resolve the "ultraviolet catastrophe" predicted by classical physics, Planck proposed that the oscillators within a heated object do not emit energy continuously. Instead, they absorb and radiate energy only in discrete packets called quanta. The energy ($E$) of each quantum is directly proportional to the radiation's frequency ($\nu$), expressed as:341

$$E=h\nu$$

Here, $h$ is Planck’s constant. Planck’s law mathematically defines the energy density radiated per unit volume at a given absolute temperature ($T$), showing that as temperature increases, the total energy emitted rises and the intensity peak shifts toward shorter wavelengths. This discovery provided the foundation for quantum mechanics, fundamentally changing our understanding of the microphysical world.143