As with any subject in such an infant and dynamic state there seem to be more questions than answers. For example, some key ones that intrigue me with regard to high redshift galaxies are:
(1.) - What are the physical conditions in z ~ 3-4 objects, and in particular, what are their mass scale lengths, masses, and metallicities? In addition, what is the nature, location and extent of the star-forming regions in these galaxies, and what are their merging rates? What is the distribution of the dust, and can we characterize the dynamical conditions and the extent of the outflows in the ISM that envelopes their star-forming regions?
(2.) - What are the properties of the youngest objects that we see, those at z >5? Again, what are their metallicities, their mass scale lengths and their masses, and what is their space density and luminosity function? The strong Ly lines, relative to the continuum, in contrast to the z ~ 3-4 galaxies suggests that they are less dusty, but is this a selection effect? How much dust do ``typical'' z >5 objects contain?
(3.) - What is the integrated SFR from z ~ 5 to z ~ 1 in the dust-enshrouded (submm) sources? How does it compare to the integrated SFR seen in the optical-UV (when corrections have been applied for the more modest dust-absorption typically found in these optically-detected sources)?
(4.) - Are we missing a whole set of objects with higher reddening/extinction that the typical E(B - V) ~ 0.2-0.3 sources found in the z ~ 3-4 ``drop-out'' sample, but which would not contain enough dust to be detectable at 850 µm with SCUBA?
(5.) - What is the form of the extinction at high redshift - and can it be characterized by a single reddening law?
These questions notwithstanding, we have made substantial progress over the last few years. Given that few galaxies were known at redshifts z >2 just five years ago, it is remarkable that we now can identify the time evolution of the star-formation rate in galaxies from redshifts z ~ 5 through to the present day. Many uncertainties remain, particularly with regard to the overall contribution from the dust-enshrouded submm sources, but the most likely situation is that by z ~ 5, within 1-2 Gyr of recombination, the SFR per comoving volume element had reached a level comparable to that at all redshifts down to z ~ 1, after which it decreased somewhat to the present day.
Interestingly, very simple arguments based on the census of the baryons at the present day, the ages of the stellar populations in ellipticals (see e.g., van Dokkum et al. 1998), plus the sizes and densities of the star forming regions at z ~ 2-5 suggest that most of the star formation we see at z >2 is making bulges.
I would like to acknowledge many valuable discussions with numerous colleagues - the remarkable progress over the last few years is due to the imagination and energy of many in our small community who have worked so hard to bring us state of the art facilities that open up new horizons. Their efforts, and those who use them imaginatively to further our understanding, and those who model the results and provide the theoretical underpinnings together make it a delight to be part of this field. I am also particularly grateful to those in our funding agencies and national centers who work, often under great pressure, to bring us the facilities and funding that allows our community to reach far and to do it so rapidly. Last but most importantly, this was a timely and fascinating conference and I am very grateful to our energetic organizer, David Block, for an excellent conference, and to Margi Crookes for her dedication to making everything work well, and to all those who helped them. The financial support from the Anglo-American Chairman's Fund and SASOL was essential to making this such a successful conference, and I would particularly like to thank those organizations.