University of Waterloo
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567 ext 32215
Fax: (519) 746-8115
Max Planck Institute for Astrophysics
Strong gravitational lenses with measured time delays between the multiple images can be used to determine the Hubble constant that sets the expansion rate of the Universe. Independent measurements of the Hubble constant are important for assessing whether the current tension, between the values inferred from the local universe and from the Cosmic Microwave Background, warrants new physics beyond the standard flat LambdaCDM model. I will describe various independent techniques for measuring the Hubble constant. A program initiated to measure the Hubble constant to <3.5% in precision from strong lenses is in progress, and I will present the latest results and their implications. Search is underway to find new lenses in imaging surveys, and I will show the bright prospects of gravitational lens time delays as an independent and competitive cosmological probe.