Its exact value has been the subject of debate, but the Hubble Constant is an important figure in modern astronomy. Featuring Mike Merrifield from the University of Nottingham. The Hubble constant tells us how quickly the universe is expanding and is usually quoted in really odd units. It also isn't actually a constant, and took many years to work out a reliable value for, and involved many arguments. Some groups thought it was around 100, others thought it was nearer to 50, and today we think it is about 67. So everyone wins! Also discussing dark energy and gravity. More videos with Mike: http://bit.ly/Merrifield_Playlist Visit our website at http://www.sixtysymbols.com/ We're on Facebook at http://www.facebook.com/sixtysymbols And Twitter at http://twitter.com/sixtysymbols This project features scientists from The University of Nottingham http://bit.ly/NottsPhysics Patreon: https://www.patreon.com/sixtysymbols Sixty Symbols videos by Brady Haran http://www.bradyharanblog.com Email list: http://eepurl.com/YdjL9