Stanford talk; heretics

I spoke today at Stanford, about the ESA Gaia Mission and it's promise for mapping (and, eventually, understanding) the dark matter in the Milky Way. I spoke about virial and Jeans methods, and then methods that permit us to image the orbits, like streams, the Snail, and orbital torus imaging. At the end of the talk Roger Blandford (Stanford) asked me about heretical ideas in gravity and dark matter. I said that there hasn't been a huge amount of work yet from the Gaia community testing alternative theories of gravity, but there could be, and the data are public. I also said that it is important to do such work, because gravity is the bedrock theory of astrophysics (and physics, in some sense). ESA Gaia potentially might deliver the best constraints in some large range of scales.