Abstract.
In 2009 the highly influential idea of a "string axiverse" was proposed. This talk attempts to review the progress myself and others have made on this idea in the last 15 years. The original probes proposed: matter power spectrum, birefringence, superradiance, and axion decays have all matured in precision both theoretically and observationally. I will then describe recent dramatic progress that has been made in constructing explicit axiverses from Calabi-Yau compactifications across the entire "Kreuzer-Skarke" database in Type IIB string theory, and the similarities and differences between such axiverses and the conjectures in 2009. I will outline the most promising phenomenology of these explicit models, and how they can be used to probe the extra dimensions of string theory observationally . I will end with some dreams for the future of this program.
(The slides will be available here)