Hi I'm having an interesting (random) discussion with Sebastian, and pointed out some nice galaxy formation pages at the IAP:

http://brunello.iap.fr/galics/GalICS/main_frames.html

There's a useful word related to these:

"phenomenological"

Its meaning is somewhere in between "theoretical" and "observational", i.e. finding formulae which are reasonable from a theoretical point of view, but not directly justified, and which can be "fit" to observations.

My guess is the constraints we have on Omega_m and Omega_Lambda could probably be described as phenomenological, since although they are very directly linked to GR, which definitely counts as theory, they're not (yet) linked into the rest of physics except by a range of "reasonable" hypotheses.

The challenge is to get these solid observational and/or (preferably "and") theoretical support...

pozd boud