gravitational redshifts; point processes

I went down to Princeton to give a seminar to the particle physicists about dark matter, and in particular what we know or could know from dynamical and kinematic measurements of stars. Before my talk, I had a great conversation with Oren Slone (Princeton) and Matt Moschella (Princeton) about gravitational redshifts. They have been thinking about where gravitational redshifts might be both measurable and physically interesting. Ideas include: Surfaces of stars, stars as a function of location in our Galaxy, and different parts of external galaxies. The magnitudes are tiny! So although the gravitational redshift is an incredibly direct tool of some gravitational dynamics, it is very hard to measure.

After my talk at Princeton, I got in a short but fun conversation with Jim Peebles (Princeton) on point processes and estimators of two-point functions. Peebles, after all, wrote down the first estimators of the clustering of large-scale structure. He admitted that the history is unprincipled: They more-or-less made things up! I presented the things that I have been discussing with Kate Storey-Fisher (NYU) and Alex Barnett (Flatiron) and he was interested. And intrigued. Can we make better estimators?