# Why acceleration at the edge of the galaxy is lesser?

I was going through Modified Inertia using the Hubble Scale Casimir effect the theory is proposed by M.E. McCulloch. The theory says it can explain different anomalies such as EmDrive, Galactic edges, etc. It explains the accelerated expansion of the universe and the galactic structure without dark energy and dark matter respectively.

Inertia from an asymmetric Casimir effect

Abstract (IOP) The property of inertia has never been fully explained. A model for inertia (MiHsC or quantised inertia) has been suggested that assumes that 1) inertia is due to Unruh radiation and 2) this radiation is subject to a Hubble-scale Casimir effect. This model has no adjustable parameters and predicts the cosmic acceleration, and galaxy rotation without dark matter, suggesting that Unruh radiation indeed causes inertia, but the exact mechanism by which it does this has not been specified.

The mechanism suggested here is that when an object accelerates, for example to the right, a dynamical (Rindler) event horizon forms to its left, reducing the Unruh radiation on that side by a Rindler-scale Casimir effect whereas the radiation on the other side is only slightly reduced by a Hubble-scale Casimir effect. This produces an imbalance in the radiation pressure on the object, and a net force that always opposes acceleration, like inertia. A formula for inertia is derived, and an experimental test is suggested.

My question is related to the basics of the galactic anomaly, why is the acceleration at the edge of the galaxy is said to be comparably less?

• I added an extract and a link, some people like to read the abstract before going off site. Will you please check I am directing people to the right place, or edit your post as you see fit. Thanks
– user108787
Dec 9, 2016 at 13:19
• I'd like to suggest that if you don't understand why our (unmodified) theory suggests that orbital speeds drop at large distance from the center of the mass distribution then you're not really ready to make any judgement about the validity of proposed replacements or modification, because you won't be able to see the implications of the changes. Dec 9, 2016 at 15:50

The rotational acceleration $a = v^2/r$, where $v$ is the stars' rotational speed and $r$ is the radial distance from the galactic centre. At the galactic edge $r$ is large so $a$ is small (since $v$ stays fairly constant with radius in galaxies). More intuitively: at the galactic edge the 'curve' of a star's trajectory is lower.