IVOA Theory IG Meeting

[Dave De Young]

Dear Nic, Gerard, et al.

I am sorry that I will be unable to attend the forthcoming Theory
IG meeting next week; it sounds like a very important meeting.
However, I did have a discussion with Bob Hanisch at our NVO
Advisory Committee meeting last week about "next steps" for the
Theory IG as seen from the IVOA "Process".  It seems that the topics
described for next week's meeting are very much on track for moving
the Theory IG into the areas of interest covered by other IVOA
working groups and eventually for the Theory IG to become a Theory
Working Group.  Once the topics to be discussed at Cambridge are
reasonably well defined, the next step seems to be an informal
"note" to the IVOA Exec that characterises the major problems, 
outlines the initial definitions of the metadata required, and
describes the next steps to be taken.  A clear area of interest is
the use of large scale simulations by observers, and hence a
description of what would be needed to make such simulations 
accessible to observers, including the basic metadata, would be
very relevant.  Some simulations have made a lot of progress in
this area, while others have done very little, as all of you know.
Also of interest are some descriptions of the interaction with,
and requirements from, other IVOA working groups such as DAL,
Registry, etc.

I notice that the Workshop announcement specifically describes
large scale cosmological simulations as an area of emphasis.  These
calculations are very complex, often with many assumptions (e.g.,
"feedback"), and they can be very high profile (e.g., Millennium).
But I urge the workshop to also include the problems involved in
other classes of complex simulations that are used by a large
fraction of the community.  These have been discussed before at
our meetings, and they include areas such as radiation transfer,
binary systems evolution including general relativity, relativistic
hydrodynamics, and 3D MHD simulations with turbulence and radiation.
I suspect the metadata issues for these classes of simulations may
be very different that those for the cosmology or purely N body
calculations.

Again, my apologies for being unable to attend.  If at the end of 
the workshop there are issues that need further development, 
particularly in the area of MHD and hydrodynamic simulations, I
would be happy to assist.  Please let me know.

Best wishes for a successful meeting.

Dave