Yale Astronomy Lectures - 20. Dark Matter

Frontiers/Controversies in Astrophysics (ASTR 160) This lecture introduces an important concept related to the past and future of the universe: the Scale factor, which is a function of time. With reference to a graph whose coordinates are the Scale factor and time, the problem of dark matter is addressed again. Cosmological redshifts are measured to determine the scale of the universe. The discovery of the repulsive, anti-gravitational force of dark energy is explained. The lecture concludes with discussion of Einstein's biggest mistake: the invention of the cosmological constant to balance gravity. 00:00 - Chapter 1. The Scale Factor 04:41 - Chapter 2. Accounting for Dark Matter in Mass of Universe 27:58 - Chapter 3. Discovery of Dark Energy 42:06 - Chapter 4. Understanding Dark Energy and Einstein's Biggest Mistake Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses This course was recorded in Spring 2007.