November 18: Cliff Burgess (McMaster University/Perimeter Institute)

Time: 2pm
Location: 2N36
 
Title: From Wilson to Lindblad: Late-time Obstacles to Reliable EFT Calculations with Horizons (and how Open EFTs can help)
 
Abstract: Precision calculations in de Sitter space (such as of inflationary predictions for primordial fluctuations) are often plagued by infrared problems and issues of secular time dependence. Similar issues about the breakdown of perturbation theory seem also to arise for information loss in black holes. This talk briefly summarizes how related problems can arise in other areas of physics, and how they are dealt with there when they do. It is argued that Master-Equation/Lindblad techniques used in areas like optics also apply to cosmology (and possibly black holes) and can tell us how to extract reliably late-time predictions. Applied to inflation they lead to Starobinsky's stochastic methods, plus small but important corrections, and this explains why stochastic inflation seems to resum IR effects in simple examples. It allows these tools to be generalized to apply more broadly. This talk describes a simple illustrative application to a qubit in Rindler space (ie an Unruh observer), where they correct earlier results by Candelas and Sciama and show in detail how and why these techniques work.