Blake Sherwin
University of Cambridge, UK

Abstract
Despite the remarkable success of the LCDM cosmological model, tensions have been reported between different low and high redshift measurements of the Hubble constant and (less significantly) the amplitude of density fluctuations (sigma_8). Although systematic errors are a likely explanation, the most exciting possibility is that these tensions are first signs of new physics. In the first part of my talk, I will discuss new methods to measure the Hubble constant from large scale structure without using information from the sound horizon scale; I will argue that this has the potential to be a promising test for many new physics models that have been proposed to solve the Hubble constant tension. In the second part of my talk, I will discuss recent progress in measurements of gravitational lensing in the cosmic microwave background (CMB), which allow the dark matter distribution to be mapped out to uniquely high redshifts. These CMB lensing measurements will soon provide some of the most powerful probes of the amplitude of density fluctuations and of neutrino masses.

2021 March 22, 15:30

IA
Online broadcast (Zoom)