Patel, Knutson, Rey

Ekta Patel (Arizona), former NYU undergraduate researcher extraordinaire, showed up at Flatiron today. We spoke about all the new ideas around making inferences about the Milky Way and it's formation and dynamics, given that we can't treat the Galaxy as a time-independent, symmetric, steady-state object (and we really can't, especially in the halo). Right now all the methods are either based on very questionable assumptions (like when can a time-dependent system be treated as a small perturbation away from a time-independent system, etc) or on super-brute-force methods (like find, among billions of simulated galaxies, a few that look like what we see!). Patel has been a pioneer in the latter, but there is lots more to do.

At Stars Meeting, Patel told us about possible strong selection effects in the MW-satellite game, which might mean that we are missing many! Missing satellite non-problem? Martin Rey (UCL) told us about how you might answer semantically causal questions about galaxy evolution with quantifiable and sensible adjustments to initial conditions in simulations. That got me all philosophical about causality in a unitary universe! And Heather Knutson (Caltech) told us about metallicity effects in the spectroscopy of directly detected exoplanets; it turns out her study is limited by the quality of the stellar metallicities. Maybe Birky (UCSD) and I could help with that?

All this after an early-morning discussion with Knutson about building a data-driven model with good causal structure to explain her exoplanet spectra. I argued that once you have the causal structure in place, good inferences become optimization (or sampling) problems. I hope this is true!