Lecture 2 - Principles of Radiative Transfer - Absorption and Emission of Radiation

Lecture 2 - Principles of Radiative Transfer - Absorption and Emission of Radiation

Electromagnetic radiation, from low-energy radio waves to ultra high energy gamma rays.., acts as our window to the Universe. This second lecture discusses the propagation of electromagnetic waves through a material medium it must pass through before reaching us, starting from distant astronomical objects.

This lecture introduces the FUNDAMENTAL PRINCIPLES OF RADIATIVE TRANSFER: Most of the information concerning the physical nature of celestial bodies (such as their chemical composition, density, temperature, etc.) comes from detecting and analyzing the electromagnetic radiation from them at various wavelengths. This lecture deals with the fundamental principles of absorption and emission of radiation in a medium. The concepts introduced in this lecture will be important for the rest of the lectures in this series.