Nine very different quantum fluids show a consistent pattern in the ratio η/s (viscosity over entropy density):
- Strongly correlated normal fluids (graphene Dirac fluid, unitary Fermi gas, quark-gluon plasma, strange metals) approach the KSS bound ħ/(4π k_B) from above.
- Macroscopically coherent fluids (superfluid ⁴He, Bose-Einstein condensates, neutron-star matter, fractional quantum Hall states, CMB photon-baryon plasma) fall far below it.
Pattern: The stronger macroscopic continuity (collective coherence) dominates, the more effective dissipation collapses.
Q₂ := σ / (π d²) = normalized transport cross-section
→ directly leads to the Planck dissipation limit τ ≳ ħ / k_B T
Is discreteness (scattering/resistance) only a boundary phenomenon of a deeper continuum?
Data sources & derivation: nine-systems.md
Mathematical derivation: derivation.md