On Fri, 07 Apr 2017 11:52:34 EDT, Eric Flesch wrote:
My point is that "dark matter" could be gravitationally opaque even as
it gravitates. We know it has different qualities than baryonic ...

[[Mod. note -- The notion of "gravitationally opaque" doesn't exist
in general relativity, so if you want this then you need to come up
with a new theory of gravity.
-- jt]]

I'm pretty sure that general relativity is not a theory of gravity.

[Moderator's note: I've kept this bit in because the rest of the post
might prompt some interesting discussion. I don't think that this is
the place to debate whether GR is a theory of gravity. -P.H.]

I
can however rephrase my point, Think of dark matter as a medium.
Compare stars in a dark matter environment to fish in a lake. Fish
don't fall because they are buoyant in the water. In a dark matter
lake, stars would similarly have some gravitational buoyancy. The
gravitational medium would modify or nullify the inverse square law.
How could it not? And that's pretty much all of my point.