There are new ways to read physical quantities from stellar spectra that boost not only measurement precision, but also allow new kinds of quantities to be inferred. This is now teaching us the formation history of our own Galaxy, when combined with the ultra-precise position measurements of the Gaia space mission: what processes set the overall radial profile of the Milky Way's disk, or the present-day orbital of any star? And how much formation memory does the Milky Way's disk retain?
