I spent the day at Princeton, hosted by Scott Tremaine (IAS). Tuesday lunch is still alive and well in Princeton, though I was shocked to find it happening in the Princeton Physics Department's Jadwin Hall. One beautiful result shown at the lunch was presented by Kento Masuda (Princeton), looking at hot exoplanets with eccentric outer companions. He has two examples that show dramatic transit timing and duration change events, presumably caused by a conjunction near the outer planet's periastron. The data are incredible and he generates a very informative (think: narrow) posterior on the outer planet's properties, despite the fact that the outer planet is not directly observed at all (and has a many-year period).
I spent most of my research time with Price-Whelan (Princeton) and Tremaine, discussing projects on the go. We spent a lot of time talking about whether it will be possible to learn fundamental things about the dark matter by building dynamical models of the stellar motions in the Milky Way. Tremaine came up with lots of reasons to be skeptical! However, if the dark matter doesn't annihilate (and even whether or not it is found in an underground lab), dynamics will be our only real tool. So I am confused. To me, it is much more interesting to model the dynamics of the Milky Way if it will tell us what the dark matter is than if it will tell us nothing more than some details about our contingent collapse and assembly history within a generic dark-matter scenario.
Getting even more philosophical, Tremaine and I discussed the question: What astronomy projects are purely descriptive of the "weather" of the Universe, and what projects get at fundamental physical processes? Even stronger: What astronomy projects might lead to changes to our beliefs about the fundamental physics itself? And how important is that, anyway? Revealing our prejudices, we both wanted to say that the most important areas of astronomy are those that might lead to changes in our beliefs about fundamental physics. But then we both wanted to say that exoplanet science is super-interesting! How to resolve this? Or is there a conflict?