The Rayleigh-Jeans formula is an equation used to describe the spectral radiance of blackbody radiation at thermal equilibrium. It was developed by physicists Lord Rayleigh and Sir James Jeans in the late 19th and early 20th century.
The main problem in deriving the Rayleigh-Jeans formula was that it predicted infinite energy at high frequencies, which was not consistent with experimental data. This became known as the "ultraviolet catastrophe."
The problem was solved by Max Planck, who proposed his famous Planck's law of blackbody radiation. This law introduced the concept of quantization of energy, which helped to accurately describe the behavior of blackbody radiation at all frequencies.
The Rayleigh-Jeans formula was one of the first attempts to mathematically describe the behavior of electromagnetic radiation at thermal equilibrium. Although it was not completely accurate, it paved the way for further developments and ultimately led to the discovery of quantum mechanics.
The Rayleigh-Jeans formula is no longer used in modern physics, as it has been replaced by more accurate equations such as Planck's law and the Stefan-Boltzmann law. However, it is still studied in the history of science and serves as an important step in the development of our understanding of blackbody radiation and quantum mechanics.