The possibility of the brightness and temperature of scattered radiation exceeding the attendant magnitudes for the incident radiation is predicted for the case of a noninverted medium, based on the analysis of radiation transfer equations. The irreversible nature of the process and impossibility of introducing ray approximation are identified as the necessary conditions.

PACS: 42.25.−p DOI: 10.1070/PU1999v042n02ABEH000569 URL: https://ufn.ru/en/articles/1999/2/e/ 000079341200005 Citation: Shepelev A V "Can the radiance increase in a noninverted medium?" Phys. Usp. 42 203–204 (1999) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Оригинал: Шепелев А В «Возможно ли увеличение яркости излучения в неинверсной среде?» УФН 169 213–215 (1999); DOI: 10.3367/UFNr.0169.199902f.0213