2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/201049We extract the shear viscosity to entropy density ratio η/s of cold fermionic atoms in the unitarity limit from experimental data on the damping of collective excitations. We find that near the critical temperature η/s is roughly equal to 1/2 in units of \hbar/k_B. With the possible exception of the quark gluon plasma, this value is closer to the conjectured lower bound 1/(4π) than any other known liquid.published versionOther Condensed MatterHigh Energy Physics - PhenomenologyNuclear Theorytext