[Cos-top] 1 - sad news (most already know); 2 - equalising of T^3 lengths

[Boud Roukema]

hi cos-top,

Probably most of us already know the sad news - Jesper Gundermann is no longer
with us - since June 2006. Jeff has submitted an interesting article with
Jesper as posthumous co-author:

http://arxiv.org/abs/astro-ph/0611640

It's not much of a consolation. Jesper was a nice guy and did good
work in cosmic topology. A year ago he (together with Jeff) responded
with lightning fast rapidity regarding my attempt to understand the
Poincare dodecahedral space, showing (if any more evidence were
necessary) that he was someone who thought about the subject deeply:
http://cosmo.torun.pl/pipermail/cos-top/2006-February/thread.html


My other theme (more pleasant) in this email is that i'm wondering if people
have any thoughts on this paper?

http://arxiv.org/abs/astro-ph/0602159

In this paper (A&A in press), we show heuristically that contrary to
what most of us (well, me anyway) believe(d) and have stated and told
to others for many years, topology and dynamics of a nearly FLRW
universe are *not* independent of one another. In other words, there
is some dependence between them. It's a weak dependence, but there is
some link there.  And it's related to the difference between an
idealised perfectly FLRW (homogeneous) universe and a real one
containing perturbations represented statistically in an approximate
way by a power spectrum.

i was also surprised when we did the calculation and found the result
that the effect tends to equalise the three lengths of a T^3 universe,
whereas all the papers that used T^3 models assumed this simply
because it's simple, without mentioning the fact that it might have a 
physical justification.

For me the obvious question to follow is whether or not the lengths of
a PDS universe would also tend to be equalised - by slightly unequal
evolution of the scale factor - keeping them to an ideal equilibrium, 
and avoiding the PDS universe becoming slightly "oblate" or "prolate".


Regards
boud