In physics, the Landau–Hopf theory of turbulence, named for Lev Landau and Eberhard Hopf, was until the mid-1970s,^{[clarification needed]} the accepted theory of how a fluid flow becomes turbulent. It states that as a fluid flows faster, it develops more Fourier modes. At first, a few modes dominate, but under stronger conditions, it forces the modes to become power-law distributed as explained in Kolmogorov's theory of turbulence.

• Landau, L. D. (1944). "К проблеме турбулентности" [On the problem of turbulence]. Doklady Akademii Nauk SSSR. 44: 339–342.
• Hopf, E. (1948). "A mathematical example displaying the features of turbulence". Communications on Pure and Applied Mathematics. 1 (4): 303–322. doi:10.1002/cpa.3160010401.