2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/212942We consider the longitudinal hydrodynamic evolution of the fireball created in a relativistic heavy-ion collision. Nonzero shear viscosity reduces the colling rate of the system and hinders the acceleration of the longitudinal flow. As a consequence, the initial energy density needed to reproduce the experimental data at RHIC energies is significantly reduced. At LHC energies, we expect that shear viscosity helps to conserve a Bjorken plateau in the rapidity distributions during the expansion.Presented at the Cracow Epiphany Conference on LHC Physics, 4-6 January 2008, Cracow, PolandNuclear Theorytext