Gustav Kirchhoff introduced the term black body in 1860 to describe an idealized object that absorbs all radiation falling upon it. He wrote in his paper for Annalen der Physik und Chemie that such bodies completely absorb rays regardless of thickness or wavelength.
Max Planck solved the spectral distribution problem in 1901 by proposing that energy exists in discrete units called quanta. He adjusted Wien's radiation law to fit experimental data while maintaining consistency with thermodynamics and electromagnetism.
The cosmic microwave background radiation maintains a temperature of approximately 2.7 Kelvin across the entire observable universe. This radiation serves as a snapshot from the time when matter and light decoupled during the early universe's history.
Josef Stefan formulated a law in 1879 stating total radiant heat power is proportional to the fourth power of absolute temperature. Ludwig Boltzmann later derived this relationship mathematically.
Thermal cameras operate most effectively between seven and fourteen micrometers where skin emission peaks. An adult human surface area measures roughly two square meters emitting net power around eight megajoules daily.