THE BLACK-BODY RADIATION PARADOX

Radiation is defined as an electromagnetic wave, and it can be any type of electromagnetic wave, as shown in the previous spectrum. Radio waves, microwaves, X-rays and gamma waves are part of the same general “type” of electromagnetic waves that are commonly labeled as “radiation.”
All materials or bodies that have inherent temperature (T ≠ 0 K) emit radiation and absorb radiation when it falls upon them. The amount of radiation emitted or absorbed depends on the material properties of that body. In general, all bodies fall between two limiting cases, bodies that are “perfectly reflecting,” such that they completely reflect all the radiations falling upon them and emit no radiations when heated. The opposite case of a perfectly reflecting body is called “black body,” and such a body absorbs all the radiations falling upon it and emits all the radiations when heated. In fact, there are no materials that exhibit such properties, but there are materials whose behavior can be closely approximated by a black or perfectly reflecting body. For example, “polished silver” can be approximated as perfectly reflecting body, and “soot” can be approximated as a black body. The emission of radiation by black bodies was one of the least understood phenomenon during the late nineteenth century, and attempts were made by physicists at that time to develop a theory of black-body radiation. Interestingly, the development of the theory of blackbody radiation presented utmost challenges to the physicists at that time. In fact, new ideas were sought to explain the phenomenon of black-body radiation, since classical theories turned out be insufficient to explain such a familiar phenomenon. These new ideas laid the foundation of the quantum theory.