Kirchhoff's law of thermal radiation rarefied material such as air, or transparent material, through which observations can be made. The interface is not a material body and can neither emit nor absorb. It is a mathematical surface belonging jointly to the two media that touch it. It is the site of refraction of radiation that penetrates it and of reflection of radiation that does not. As such it obeys the Helmholtz reciprocity principle. The opaque body is considered to have a material interior that absorbs all and scatters or transmits none of the radiation that reaches it through refraction at the interface. In this sense
A-sound Best Sound ). A-Sound put out their debut album in July 2008: Release. It was the first Mongolian rock album to feature some songs in English. The album featured many popular songs, including: "Uyanga," "Shine On," and "Forever." "Uyanga" is a popular girl's name and is a pleasant song sung in Mongolian. "Shine On" and "Forever" are two slices of immaculate pop song-craft, and to music critic (among other things) Brian Offenther, should have been international pop smashes. In "Forever," lead singer Temuulen's crystal clear voice really sours. In early 2009, a deluxe version of Release was put out and