At group meeting, Ana Bonaca (Yale) told us about inferring the potential and mass distribution in the Milky Way using pairs of cold stellar streams. She seems to find—even in the analysis of fully simulated data sets—somewhat inconsistent inferences from different streams. They aren't truly inconsistent, but they look inconsistent when you view only two parameters at a time (because there are many other nuisane parameters marginalized out). She shows (unsurprisingly) that radial velocity information is extremely valuable.
Brian McFee (NYU) talked about measuring rhythm in recorded music. Not tempo but rhythm. The idea is to look at ratios of time lags between spectrogram features (automatically, of course). He showed some nice demonstrations with things that are like "scale transforms": Like Fourier transforms but in the logarithm of frequency.
In the afternoon, Bonaca, Foreman-Mackey, and I discussed the relationships between dynamics and geometry and statistics. I gave a very powerful argument about why sampling is hard in high dimensions, and then immediately forgot what I said before writing it down. We discussed new MCMC methods, including Foreman-Mackey's proposals for Hamiltonian MCMC in an ensemble.