Yousuf Khan wrote:

MOND explains the rotation curves of galaxies extremely well;

Ballmer explains the spectrum of the Hydrogen atom really well too.

Dark Matter explains the same things not so well.

No.

Dark Matter explains
galactic cluster interactions extremely well; MOND explains the same
things not so well. That's the long and short of it.

MOND has extreme difficulties with anything but rotation curves.


/Dark Fields/ is an attempt to make MOND work better at the cluster
level.

There are two ponderous concepts at work here.

i) MOND has an entirely arbitrary interpolation function that has no real
world constraints on it, and that still isn't good enough.
ii) MOND proponents feel that dark matter (and presumably, energy) are
unphysical or wrong for some personal reason but still feel that MOND and
its' extensions which use increasingly larger amounts of arbitrary
sourceless fields is a more intuitive / understandable / correct model.

There is a lot of cajoling needed to make Dark Matter work well
within the galactic scale too. So it looks like neither theory works
well outside their on size scale.

Except dark matter works well enough on the galactic scale. What it has
difficulties amount to fine tuning issues which just might be related to our
ignorance of galactic structures and oversimplified models.


SPACE.com -- Dark Horse Challenges Dark Matter to Explain Missing Matter
"When applied to just galaxies, MOND can predict very well the behavior
that astronomers observe. But when MOND is applied to larger structures
like clusters of galaxies, it fails. To make MOND work for clusters, it
must include more complicated concepts, such as entities called dark
fields, which are different from dark matter, but work in a similar way
to alter the amount of gravity present."

*laughs*

Oh yes, dark FIELDS. That's entirely more acceptable than dark MATTER. I'm
sure that theory will hit the ground /running/.

http://www.space.com/scienceastronom...ng-matter.html

Yousuf Khan