Talk:Weyl's postulate/to do

tasks for expert:
 * write and link to articles on ADM formalism,
 * explain hyperslices and evolving geometry therein,
 * write and link to articles giving explicit examples of congruences with zero and nonzero vorticity in flat and curved spacetimes,
 * explain therein the relation to locally non-rotating and to fluid dynamics,
 * write articles on Bianchi dusts, Wainwright solutions, etc.