English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The MOND limit is shown to follow from a requirement of space-time scaleinvariance of the equations of motion for nonrelativistic, purely gravitationalsystems; i.e., invariance of the equations of motion under (t,r) goes to(qt,qr), in the limit a0 goes to infinity. It is suggested that this shouldreplace the definition of the MOND limit based on the low-acceleration behaviorof a Newtonian-MOND interpolating function. In this way, the salient, deep-MONDresults--asymptotically flat rotation curves, the mass-rotational-speedrelation (baryonic Tully-Fisher relation), the Faber-Jackson relation,etc.--follow from a symmetry principle. For example, asymptotic flatness ofrotation curves reflects the fact that radii change under scaling, whilevelocities do not. I then comment on the interpretation of the deep-MOND limitas one of "zero mass": Rest masses, whose presence obstructs scaling symmetry,become negligible compared to the "phantom", dynamical masses--those that somewould attribute to dark matter. Unlike the former masses, the latter transformin a way that is consistent with the symmetry. Finally, I discuss the putativeMOND-cosmology connection in light of another, previously known symmetry of thedeep-MOND limit. In particular, it is suggested that MOND is related to theasymptotic de Sitter geometry of our universe. It is conjectured, for example,that in an exact de Sitter cosmos, deep-MOND physics would exactly apply tolocal systems. I also point out, in this connection, the possible relevance ofa de Sitter-conformal-field-theory (dS/CFT) duality.

The MOND limit from space-time scale invariance