  Metallic fluid H has been made by dynamic compression decades after Wigner
and Huntington (WH) predicted its existence in 1935. The density obtained
experimentally is within a few percent of the density predicted by WH. Metallic
fluid H was achieved by multiple-shock compression of liquid H2, which
compression is quasi-isentropic and H is thermally equilibrated in experiments
with 100 ns lifetimes. Quasi-isentropic means compressions are isentropic but
with sufficient temperature and entropy to drive a crossover from liquid H2 to
degenerate fluid H at 9-fold compression and pressure P=140 GPa (1.4 Mbar). The
metallic fluid is highly degenerate: T/TF 0.014, where temperature T=3000 K and
Fermi temperature TF =220,000 K, respectively, at metallization density 0.64
mol H/cm3.
  Dynamic compression is achieved by supersonic, adiabatic, nonlinear
hydrodynamics, the basic ideas of which were developed in the Nineteenth
Century in European universities. Today dynamic compression is generally
unfamiliar to the scientific community. The purposes of this paper are to
present a brief review of (i) dynamic compression and its affects on materials,
(ii) considerations that led to the sample holder designed specifically to make
metallic fluid H, and (iii) an inter-comparison of dynamic and static
compression with respect to making metallic H.
