This directory contains the presentation developed for
the 2019 AAS/SPD Hale Prize lecture.

It is the talk as given.

Some of the figures are from prior published articles.
Most of these have terse citations.  There will be
a more complete reference list here soon.

The 4 movies were all generated for the talk.
Copies of the 3 mp4 and 1 mpg have been
added here.

Phil