To Ken G

1. That bet sounds fine. Don't expect me to cave for things like dark-matter reports in the galaxy collisions, or other phony stuff, and I will expect you to defend to the end. Should be interesting.

2. You know MOND is still alive and well in some circles. Can you prove it wrong? They simply said that Newton's law had to be modified to get speed matches for galaxies and thus avoid dark matter, but their mods had to be special for nearly every case. Does that prove it wrong? I think so.

3. I'm back to reading Binney and Tremaine to find out how surface light is measured so I can talk with some knowledge on it. Pages 8,9,16,17 have good basic info. They conclude (p16) that our solar neighborhood of the galaxy has an SMD of 75 msuns/pc^2 (made up of all components, stars and non-star ordinary matter) and a surface brightness of 15 Lsunvs (sun visible light intensities/ pc^2)

They assume all the light comes from stars alone. Dividing 75/15 they get 5 msuns/Lsunv as a mass/light ratio. (So that's where the 5 came from). They then use 5 to estimate the mass of the Galaxy, assuming 5 as constant over the entire radius. This is where I think the problem lies. I believe the average M/L ratio is closer to 10 for most galaxies, and that the M/L varies a lot for different galaxies and over radius in a given galaxy. Because of the possible situation where there is very low average light, I think it should be a L/M ratio to be more realistic.

More later.

Ken Nicholson