Fluid jets are all around us: from inkjet printing, to the "Old Faithful" geyser in Yellowstone National Park, to cosmological jets several thousand light years long.
A Northwestern University researcher with collaborators from Cambridge University, Oxford University, and Centro Nacional de Biotecnología have recently verified the classical Landau-Squire theory in the tiniest submerged jet. The diameter of their jets were in the range of 20 to 150 nanometers, which is the length of just a few hundred water molecules lined up in a row.