Lecture 33: Einstein's Universe

How did we discover that the Universe is Expanding? What does it mean that it is expanding? This lecture introduces Hubble's Law, the observational evidence that the Universe is systematically expanding. As galaxies get more distant from us, the apparent speed of recession gets l ...  Show more

How do we measure distances on cosmic scales? This lecture describes the rungs in the cosmic distance ladder from measuring the AU in our own Solar System out into the Hubble expansion of the universe. These distances form the basis of the measurements that let us piece together ...  Show more

A new podcast, Astronomy 141, Life in the Universe, is available for those interested in continuing an exploration of topics in modern astronomy. 

What is Astronomy? What is Science? What is the course all about? Brief introductory remarks after going over course mechanics on the first day of Astronomy 161 for Autumn Quarter 2007. Recorded 2007 Sep 19 in 1000 McPherson Lab on the Columbus campus of The Ohio State University ...  Show more

Are we alone in the Universe? This lecture explores the question of how we might go about finding life on planets around other stars. Rather than talking about speculative ideas, like the Drake Equation or SETI, I am instead taking the approach of posing it as a problem of what t ...  Show more

Get ready to explore a 10 billion year old mystery! A closely bound duo of energetic quasars, the hallmark of a pair of merging galaxies, have been discovered when the Universe was only 3 billion years old. What secrets do these quasars hold and why have they lasted so long? Join ...  Show more