Three related proposals for a theoretical definition of turbulence

We pull together some developments in turbulence research to make three propositions: (1) when the steady-state solution of any transport equation produces multi-valued velocity fields, the system described is turbulent, (2) turbulent–laminar transitions are marked by the occurrence of a singularity in the derivative of velocity with respect to time, (3) the onset of turbulence in noble gases may be described quantum mechanically using the cell model of a gas, producing two testable laws describing the critical pressure of a turbulent gas.