  Standard textbooks will state that hydrodynamics requires near-equilibrium to
be applicable. Recently, however, out-of-equilibrium attractor solutions for
hydrodynamics have been found in kinetic theory and holography in systems with
a high degree of symmetry, suggesting the possibility of a genuine
out-of-equilibrium formulation of hydrodynamics. This work demonstrates that
attractor solutions also occur in non-conformal kinetic theory and spatially
non-homogeneous systems, potentially having important implications for the
interpretation of experimental data in heavy-ion and proton-proton collisions
and relativistic fluid dynamics as a whole.
