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
Make a Sound Make a Sound Make a Sound is the only album by American rock band Autopilot Off. In April and May, the group supported Rufio on their headlining US tour. "Make a Sound" was released on April 13 through Island Records and produced by then-Sum 41 producer and manager Greig Nori. The Japanese version of "Make a Sound" includes a bonus track titled "Raise Your Rifles". There is also a limited edition print of the album, that, as well as the Japanese bonus track, includes two additional exclusive songs. "Make A Sound" appears in the soundtrack for "", "Chromatic Fades" in