All aboard the gravitational waves bandwagon--with the first direct observation of gravitational waves announced this week, Katie's dusting off her physics PhD for a very special gravity-related episode. Discussed in this episode: what are gravitational waves, how are they detected, and what does this announcement mean for future studies of the universe.
Relevant links:
http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html
https://www.ligo.caltech.edu/news/ligo20160211