  The inertial-interval energy spectrum of strong magnetohydrodynamic (MHD)
turbulence with a uniform background magnetic field was observed numerically to
be close to $k^{-3/2}$ by a number of independent groups. A dissenting opinion
has been voiced by Beresnyak, A. 2011, PRL, 106, 075001-. 2012, MNRAS, 422,
3495-. 2014, ApJ, 784, L20 that the spectral scaling is close to $k^{-5/3}$.
The conclusions of these papers are however incorrect as they are based on
numerical simulations that are drastically unresolved, so that the discrete
numerical scheme does not approximate the physical solution at the scales where
the measurements are performed. These results have been rebutted in our more
detailed papers Perez, J. C., Mason, J., Boldyrev, S., & Cattaneo, F. 2012,
PRX, 2, 041005-. 2014, ApJL, 793, L13; here, by popular demand, we present a
brief and simple explanation of our major criticism of Beresnyak's work.
