Critical balance in magnetohydrodynamic, rotating and stratified
  turbulence: towards a universal scaling conjecture
  It is proposed that critical balance - a scale-by-scale balance between the
linear propagation and nonlinear interaction time scales - can be used as a
universal scaling conjecture for determining the spectra of strong turbulence
in anisotropic wave systems. Magnetohydrodynamic (MHD), rotating and stratified
turbulence are considered under this assumption and, in particular, a novel and
experimentally testable energy cascade scenario and a set of scalings of the
spectra are proposed for low-Rossby-number rotating turbulence. It is argued
that in neutral fluids, the critically balanced anisotropic cascade provides a
natural path from strong anisotropy at large scales to isotropic Kolmogorov
turbulence at very small scales. It is also argued that the kperp^{-2} spectra
seen in recent numerical simulations of low-Rossby-number rotating turbulence
may be analogous to the kperp^{-3/2} spectra of the numerical MHD turbulence in
the sense that they could be explained by assuming that fluctuations are
polarised (aligned) approximately as inertial waves (Alfven waves for MHD).
