Perspective on MOND emergence from Verlinde's "emergent gravity" and its
  recent test by weak lensing
  We highlight phenomenological aspects of Verlinde's recent proposal to
account for the mass anomalies in galactic systems without dark matter -- in
particular in their relation to MOND. Welcome addition to the MOND lore as it
is, this approach have reproduced, so far, only a small fraction of MOND
phenomenology, and is still rather tentative, both in its theoretical
foundations and in its phenomenology. What Verlinde has extracted from this
approach, so far, is a formula -- of rather limited applicability, and with no
road to generalization in sight -- for the effective gravitational field of a
spherical, isolated, static baryonic system. This formula cannot be used to
calculate the gravitational field of disk galaxies, with their rich MOND
phenomenology. Notably, it cannot predict their rotation curves, except
asymptotically. It does not apply to the few-, or many-body problem; so, it
cannot give, e.g., the two-body force between two galaxies, or be used to
conduct N-body calculations of galaxy formation, evolution, and interactions.
The formula cannot be applied to the internal dynamics of a system embedded in
an external field, where MOND predicts important consequences. etc. MOND is
backed by full-fledged, Lagrangian theories that can be, and are, routinely
applied to all the above phenomena, and more. Verlinde's formula, as it now
stands, strongly conflicts with solar-system and possibly earth-surface
constraints, and cannot fully account for the mass anomalies in the cores of
galaxy clusters (a standing conundrum in MOND). The recent weak-lensing test of
the formula is, in fact, testing a cornerstone prediction of MOND, one that the
formula does reproduce, and which has been tested before in the very same way.
