Do you mond if I put this here?

[robinson]

* Mordehai Milgrom [http://arxiv.org/abs/0908.3842 ''MOND: time for a change of mind?'']

Not sure where this would go, a fascinating paper, one wonders how it fits in the dark and murky world of astronomy.

Scathing rebuke of Dark Matter and more.

[jjohnson]

Thanks for posting this. I've read the paper. What seems to be constantly missing from "their" calculations, among other things, is holistic modeling that includes the plasma physics with the conventional gravitation-only physics. Peratt's simulations (particle in cell software running on a supercomputer) could include or exclude gravity's effect on plasmas with little difference noted, if I recall correctly. However, modeling a galaxy accurately means that you have to include all the forces operative, including lumpy masses in a variety of sizes and proximities, the plasma-generated forces from the various filamentary structures present, radiation pressures at smaller distances, etc. If you only run such a model with a couple of forces turned on, MOND or not, the probability of an accurate answer seems dismally low. -and that's what we've seen, with the resultant tweaks, adjustments and modifications coming along to "refine" the model so that it runs a little better, limping along on gravity power alone.

Take a look at some of the current plasma physics textbooks used for astronomy (use the "look inside" feature). I am a layman, but I've read Peratt's textbook twice, Physics of the Plasma Universe, and read the results of his measured lab experiments, his PIC simulations of large scale plasmas, and read most of his papers. Today's texts are still getting much of their plasma physics wrong, constantly suggesting that a plasma is no more than a hot gas and subject to the same magnetohydrodynamic forces and reactions as the Navier-Stokes equations give for supersonic airflow over a body or an airfoil. This is a major disconnect from Peratt's and Alfven's observations and rules of the road. Transfer of power across intergalactic distances and charge exchanges powering stars externally can't be solved with their limited incorporation of electromegnetic phenomena. Birkeland had it very close to right at the beginning of the 20th century, in my limited judgment, when he modeled our sun-planet systems physically using only electricity and magnetism on his terellas, and actually ignored gravity as it had little significance at the local scale of effects.

Simulations are great, and are of invaluable assistance in supporting ideas and tentative hypotheses if they are as complete and accurate as we can make them (which is the stage of the EU paradigm at the moment) but measurements, observations, winnowing out weaknesses and hands-on close-up measurements are ideal. Since we won't get the hands-on part at other stars we will have to do as much confirmation here at home as we can, and, as always, extrapolate by extension and assumptions of self-similarity to the rest of the observable universe, until proven or demonstrated otherwise.

Jim

[mharratsc]

Here's Wal Thornhill's ideas regarding E-MOND:

http://www.holoscience.com/news.php?article=q1q6sz2s

This sound very plausible, and like he posts is an actual theory because he provides several scenarios in which it could be tested. Now that's a theory!


Mike H.

[robinson]

I'm just happy to not have started a thread in the wrong forum.