Note: Although you can no longer find these videos on YouTube, you can find them available on this CERN website.
Sean Carroll, a physics professor at Caltech, has a knack for making science publicly accessible. He writes regularly for the blog Cosmic Variance, and you have perhaps seen him on the History Channel, Science Channel, or The Colbert Report. Yesterday, he announced that five lectures he gave at CERN now appear online, and it all begins with an Introduction to Cosmology, or the origin and structure of the universe. Then come lectures on Dark Matter, Dark Energy, Thermodynamics and the Early Universe, and Inflation and Beyond. The lectures (all nicely packaged together at Cosmic Variance) will appear in the Physics Section of our collection of Free Courses Online. You may also want to visit two related videos recently featured on OC: