Concluding remarks: Directing and controlling materials and molecules

Controlling the macroscopic properties of materials, particularly quantum materials, via external inputs such as optical fields is a key goal of modern physical science. The Faraday Discussion presented a cross section of current experimental and theoretical progress with mostly ultrashort pulse excitations with frequencies ranging from the X-ray to the THz regions of the spectrum. This paper offers a perspective on the meaning of control in different scientific and engineering contexts. Despite the enormous challenge of implementing full feedback control on the types of material of interest in this discussion, I sketch such a system taken from a photosynthetic context to provide inspiration for future development in control of materials.