``It is known that galaxies in dense clusters like the Coma cluster were the first to form in the Universe, and so our results may therefore imply that many small, dark matter halos without galaxies existed early in the history of the Universe.''
http://astronomy.swin.edu.au/coma/project-overview-objective1.htm
When that is coupled with this:
http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/galaxydist.htm
I get the idea (I think) that dark matter acts like a `armature' about which the globs of luminous matter are attracted to, stick near, and evolve around.
``i think this whole thing of universities posting lectures in video format is one of the greatest things the web has done for us to date.''
I sure do too. But the UC system seems pretty stingy. They'll post an invited special lecture, but not the usual class stuff. Maybe it's the Regents and their copyright fetish.
``the problem is that you do need some general relativity to keep the picture sane.'' LS
Could you open this up just a little so I can get a hint at what to think about. Susskin says space is flat, which sort of surprised me. It was a disappointment too, because I had spent so much time working on my brain to figure out (re-conceive) the curvature of a gravitational field, relativistic transforms, and the large scale curvature of spactime, paths as geodesics and all those other concepts and vocabulary. On the other hand, because a lot of that was missing, I could follow the points Susskin was making.
This also reminds me to mention the gravitational lens in the above link. They show its effect on a building facade. Studying it for a few moments, it strongly reminds me of looking at a cone at its apex with its surface coated in a mirror---a visual representation of a conformal transformation.
``IMHO, is to think about the ground state energies on a spherical surface who's scale factor is growing.'' LS
This is another thing that needs a hint and some development. Send a link if you want.
I thought Susskin did sort of suggest this concept when he drew his line (that represented a surface) and kept adding dots as the line grew longer. But I didn't get a detailed idea of what he was doing.
On the link to the Casimir effect:
``Bohr was referring to a strange prediction of the quantum theory of fields, which says that there is no such thing as perfectly empty space. Instead, even supposedly empty space is endowed with "virtual" photons and other particles that constantly pop in and out of existence everywhere. And Bohr's idea seemed to work: using only these zero-point fluctuations as his guide, Casimir successfully derived his formula for the long-distance van der Waals force between atoms...''
Just starting Susskin's lecture 5. This is the intro to GR, I think. He sets up Riemann spherical geometry, the preamble. Maybe all that work wasn't wasted after all...
CG