Lecture 40: The Once and Future Sun

We are not made of the same matter as most of the Universe! This surprising conclusion, that the ordinary matter we are made of (protons, neutrons, and electrons) constitute only 13% or so of the total matter in the Universe, the rest being in the form of Dark Matter. Further, th ...  Show more

Can we travel through time? This is not a frivilous, science-fiction kind of question. Certain restricted kinds of time travel are in fact allowed by classical General Relativity. This lectures takes up this question, and looks at some of the surprising answers that have been fou ...  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