Adrian Price-Whelan (Princeton) resolved some of our code differences today as unit or dimensions differences. That was good! But we still have the problem that different elements (in comparison with kinematics) lead to different inferences about orbits in the Milky Way disk. Don't know what to do about that! Either the data are wrong, or there is a big discovery here.
Ana Bonaca (Harvard), Price-Whelan, and I discussed how to build a pseudo-likelihood for comparing the models that Bonaca has for a stream perturbation to the real data. This is a bit of a hard problem, because we want objectives that improve as the agreement improves, but we don't want to build a fully generative model of the data. Why not? because we don't have a good generative model, and perturbations away from a bad generative model could lead to very wrong inferences. All we want, after all, is a rough sense of what kinds of events are consistent with the data.
In the afternoon, I gave the Aspen Center for Physics Colloquium. I spoke about Gaia and dark matter, but I also threw in my thinking about the inference of Solar System dynamics in the 17th Century: We would do it very differently now! I have much more to say but I am too tired to write it here.
No comments:
Post a Comment