Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: The Kompaneets equation describes the time evolution of the energy distribution of particles that have participated in this process. The y-parameter was introduced by Sunyaev and Zeldovich, who studied the inverse type of this phenomenon in the cosmic microwave background. The Klein-Nishina formula calculates the differential cross section for this phenomenon, which reduces to a Thomson process in the limit of low photon energies. The change in wavelength that occurs in this process depends as the cosine of the angular change of the affected photon's direction. FTP identify this process in which a photon collides with an electron, resulting in a decrease in its energy.
A:
Science