####
Description

Frontiers/Controversies in Astrophysics (ASTR 160)
Class begins with a review of magnitudes and the problem set involving magnitude equations. Implications of the Hubble Law and Hubble Diagram are discussed. Professor Bailyn elaborates on the Big Bang theory of cosmology and addresses controversial questions related to the age, development, and boundaries of the universe. The fate of the universe, and possibly its end (known as the Big Crunch) are addressed. Imagining an expanding three-dimensional universe is proposed. The lecture ends with a question-and-answer session during which students inquire about a variety of topics related to cosmology, such as the center of the universe, its current expansion, and hypothetical collapse.
00:00 - Chapter 1. Review of Magnitudes
07:38 - Chapter 2. Implications of Hubble's Discoveries on the Aging Universe
26:36 - Chapter 3. Conceptualizing a Three-Dimensional Universe
34:22 - Chapter 4. Q&A: The Big Bang, the Expansion, and the Big Crunch
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Spring 2007.

## Comments, questions and answers