Quantum mechanics, superfluids, and capillary fluids are closely related: it
is thermodynamics that links them. In this paper, the Liu procedure is used to
analyze the thermodynamic requirements. A comparison with the traditional
method of divergence separation highlights the role of spacetime. It is shown
that perfect Korteweg fluids are holographic. The conditions under which a
complex field can represent the density and velocity fields of the fluid, and
where the complex scalar field becomes a wave function of quantum mechanics,
are explored. The bridge between the field and particle representations of a
physical system is holography, and the key to holography is the Second Law of
thermodynamics.Comment: 33 pages, no figures, accepted in Physics of Fluid