Lecture 27: Deep Time - The Age of the Earth
How old is the Earth? This lecture reviews the idea of cyclic and\nlinear time, since how you view time determines whether the question of\nthe age of the Earth is even meaningful. We then review various ways\npeople have estimated the age of the Earth, starting with historical\nages that equate human history with the history of the Earth proper, and\nthen see how various physical estimates, which do not make an appeal to\nhuman history, were made. This brings us to the technique of\nradioactive age dating of the oldest rocks, leading to our current best\nestimate of 4.5+/-0.1 Billion years for the age of our planet. Recorded\n2006 Oct 30 in 100 Stillman Hall on the Columbus campus of The Ohio\nState University.