  The standard model for gravitational structure formation in astrophysics,
astronomy, and cosmology is questioned. Cold dark matter (CDM) hierarchical
clustering cosmology neglects particle collisions, viscosity, turbulence and
diffusion and makes predictions in conflict with observations. From Jeans 1902
and CDMHC, the non-baryonic dark matter NBDM forms small clumps during the
plasma epoch after the big bang that ``cluster'' into larger clumps. CDM halo
clusters collect the baryonic matter (H and He) by gravity so that after 300
Myr of ``dark ages'', huge, explosive (Population III) first stars appear, and
then galaxies and galaxy clusters. Contrary to CDMHC cosmology,
``hydro-gravitational-dynamics'' HGD cosmology suggests the diffusive NBDM
material cannot clump and the clumps cannot cluster. From HGD, the big bang
results from an exothermic turbulent instability at Planck scales (10^{-35} m).
Turbulent stresses cause an inflation of space and fossil density turbulence
remnants that trigger gravitational instability at protosupercluster masses
(10^{46} kg) in the H-He plasma. These fragment along plasma turbulence vortex
lines to form protogalaxy masses (10^{42} kg) just before the transition to
gas. The gas has x10^{-13} smaller viscosity, so it fragments at planetary and
globular-star-cluster masses (10^{25} and 10^{36} kg) to form the baryonic dark
matter (BDM). Observations from the Hubble Space Telescope show protogalaxies
(PGs) in linear clusters reflecting their likely fragmentation on plasma vortex
lines. From merging BDM planets, these PGs gently form small stars in globular
clusters <1 Myr after the big bang without the dark ages, superstars, or
reionization of CDM cosmology.
