"In matter of fact, whether MOND is a fundamental theory or not, the very special and central role the constant a0 plays in galaxy dynamics is well established and is here to stay. For instance, you will find it everywhere in the data itself. All round systems, from giant molecular clouds, through globular clusters and elliptical galaxies, to clusters of galaxies lie, in the mass-radius plane, near the line with constant M/R2. The value of this ratio when multiplied by G gives a0. Another example: the baryonic Tully-Fisher relation agrees well (over many orders of magnitude in mass) with a relation of the form α M = V–4. The proportionality constant α has dimensions of G times acceleration and when divided by G gives a0 (this is independent of the previous appearance as it refers to asymptotic regions in the galaxies)."