The Broken Cosmic Distance Ladder

Measuring distances to astronomical objects outside our Galaxy is a surprisingly hard challenge: it wasn't until 1923 that Edwin Hubble obtained proof that Andromeda is indeed a galaxy in its own right. Today, astronomers extend distance measurements in the cosmos to the edge of the visible Universe, building up a 'cosmic distance ladder' made of several rungs. This talk will explore a major conundrum of contemporary astronomy: as observations have become more precise, the distance ladder appears today to be broken.A lecture by Roberto TrottaThe transcript and downloadable versions of the lecture are available from the Gresham College website:https://www.gresham.ac.uk/lectures-and-events/cosmic-distanceGresham College has been giving free public lectures since 1597. This tradition continues today with all of our five or so public lectures a week being made available for free download from our website. There are currently over 2,000 lectures free to access or download from the website.Website: http://www.gresham.ac.ukTwitter: http://twitter.com/GreshamCollegeFacebook: https://www.facebook.com/greshamcollegeInstagram: http://www.instagram.com/greshamcollegeSupport the show