Ryan Hynd University of Pennsylvania We will consider collections of point masses that only interact via perfectly inelastic collisions. As such collections conserve mass and momentum, they will correspond to solutions of an appropriate system of differential equations. These equations have been used in astronomy to model the expansion of matter without pressure and they also play a central role in the theory of optimal mass transport. In this talk, we’ll discuss how to derive the equations, show how to find solutions in some cases and present some open problems. BIO: When I was a student at Palm Beach Community College (PBCC), I struggled mightily with my introductory calculus and physics courses. Nevertheless, I stuck with it and received a lot of encouragement from my physics professors. I was especially fortunate that Georgia Tech admitted me as a transfer student. My intended major was computer engineering. However, I found that I really liked learning about math, so I decided to change my major to mathematics. This was one of the best decisions I ever made. I thoroughly enjoyed studying mathematics at Georgia Tech, and I encountered professors who recognized my abilities and who helped me prepare for graduate school in mathematics. While I wasn't the most talented PhD student at UC Berkeley, I was just as excited about having the opportunity to do math as my peers, and I had a decent idea about what I needed to do to succeed. Moreover, I was lucky to find an excellent advisor in Craig Evans and a great mentor in Ted Hill. I cherish the time I spent at UC Berkeley, which set me up for a career in research and teaching in mathematics.