Dissipation and noise in effective field theories for cosmology

Dissipation and noise arise from the incomplete modelling of unknown environments through which light and gravitational waves propagate. In this talk, I will introduce a framework that extends effective field theories to account for these effects. I will highlight how symmetries, locality, and unitarity impose constraints on dissipation and noise. Finally, I will explore the resulting phenomenology in the early and late universe, with a focus on the potential observational signatures of these effects.