Peter Debye explained the heat capacity of a solid by counting a spectrum of quantized elastic vibrations. In the Debye model, a cutoff ensures the correct number of modes, while the low-frequency acoustic spectrum gives heat capacity proportional to at sufficiently low temperature. At high temperature, the same construction approaches the classical Dulong-Petit law. Connecting elastic vibrations with quantum occupation explains why a solid stores much less thermal energy at low temperature than a classical mode count predicts.[ref]
Zur Theorie der spezifischen Wärmen by Peter Debye. Annalen der Physik 344, 789–839 (1912), vibrational-spectrum heat-capacity theory
A physicist.[ref]
https://chemistry.cornell.edu/peter-j-w-debye. Independent biographical identity and professional specialization
Portrait of Peter Debye
. Schmelhaus / ETH Zürich; ETH-Bibliothek Zürich, Bildarchiv, Portr 00836. CC BY-SA 3.0, via Wikimedia Commons. Source. Articles by others on the same topic
Peter Debye (1884-1966) was a Dutch-American physicist and chemist renowned for his contributions to the fields of physical chemistry and electrodynamics. He is best known for his work on the Debye model, which describes how dielectric materials respond to electric fields. He also investigated the behavior of polar molecules, leading to the introduction of the concept of the dipole moment and Debye temperature, which relates to specific heat capacities in solids.