Fig. 1: Breakthroughs in thermal emission engineering.

a According to Planck’s law, the broadband emission spectrum (tied to isotropic and unpolarized thermal radiation) of a black body in thermal equilibrium only depends on the temperature. b Thermal emission can be controlled by structuring the matter, enabling narrowband, directive, and polarized radiation. c Modulating temporally the optical properties of a medium enables more sophisticated ways to obtain similar effects, yielding the emergence of new physics, such as non-local correlations, overcoming the black-body spectrum, or dynamical vacuum effects.