Dark Matter in the Universe - Lawrence Krauss
On 12 - 13 April 2010, Lawrence Krauss returned to YBC to give a general lecture and a 2-day mini course.
On Monday morning, he gave a 90-minute general lecture on dark matter in the universe, explaining that only about 15% of the matter in the universe (stars and galaxies) is visible -- and that the vast majority of matter is invisible "dark" matter and dark energy, which is detectable only indirectly by the gravitational effect they have on visible stars and galaxies.
He gave an introduction to what dark matter is all about, how researchers predicted its existence and projects that are ongoing to directly detect dark matter and its composition. Frank Wilczek has proposed that particles that he calls axions are a candidate for dark matter.
On the Monday and Tuesday afternoons, Lawrence taught the YBC physics class, doing a review of simple harmonic motion and waves, from a different perspective, and reports from the students is that this helped everything "click into place."