Explore the non-equilibrium dynamics of scalar fields in this 39-minute lecture by Rajdeep Sensarma from the International Centre for Theoretical Sciences. Delve into the concept of (pre)thermal states and their role in complex systems driven by periodic and quasi-periodic forces. Part of a program on Periodically and Quasi-Periodically Driven Complex Systems, this talk contributes to discussions on topics such as terahertz and infrared driven quantum matter, shaken optical lattices, Floquet time crystals, and localization-delocalization physics. Gain insights into the interplay between closed quantum systems, open quantum systems, and gauge theory of coupling between matter and radiation.