  The late Gerry Brown was not shy to tackle complex scientific problems that
took time to play out but yielded in the end a deeper understanding of
many-body phenomena. In this note, prepared for a memorial volume in his honor,
we provide a perspective on a couple of outstanding scientific puzzles that
have their origin in our understanding of the thermalization of matter in
ultrarelativistic heavy ion collisions, and possibly, in high multiplicity
proton-proton and proton-nucleus collisions.
