  We discuss the state-of-the-art and remaining challenges in the fundamental
understanding and technology development for controlling light-matter
interactions in nanophotonic environments in and away from thermal equilibrium.
The topics covered range from the basics of the thermodynamics of light
emission and absorption, to applications in solar-thermal energy generation,
thermophotovoltaics, optical refrigeration, personalized cooling technologies,
development of coherent incandescent light sources, and spinoptics.
