Increasing Accuracy and Increasing Tension in Ho [Applied Physics/Physics Colloquium]

Increasing Accuracy and Increasing Tension in Ho
Tuesday, October 24, 2017 - 4:15pm
Hewlett 200
Wendy Freedman (Hanna Visiting Scholar, Univ. of Chicago)
Abstract / Description: 


he Hubble constant, Ho, provides a measure of the current expansion rate of the universe. In recent decades, there has been a huge increase in the accuracy with which extragalactic distances, and hence, Ho can be measured. While the historical factor-of-two uncertainty in Ho has been resolved, a new discrepancy has arisen between the values of Ho measured in the local universe, and that estimated from cosmic microwave background measurements, assuming a Lambda cold dark matter model. I will review the advances that have led to the increase in accuracy in measurements of Ho, as well as describe exciting future prospects with the James Webb Space Telescope (JWST) and Gaia, which will make it feasible to measure extragalactic distances at percent level accuracy in the next decade

APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore