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1. Introduction

In 1984, as astro-particle physics was beginning to thrive, the first Inner Space/Outer Space workshop was organized [1]. The contents of that first volume reflect well on the state of the field at that time. Concerning pre-big bang nucleosynthesis (BBN) cosmology, the major focuses were centered on inflation, magnetic monopoles, Kaluza-Klein cosmology, supersymmetry, supergravity, and quantum gravity. Inflation was still new enough that there was a strong interest in finding working models of inflation using realistic particle physics. Particular emphasis was placed on inflationary models in the context of supergravity. After the demise of old and new inflation in the context of SU(5), the inflaton was created to allow a framework for constructing toy models [2]. After fifteen years, the search for a realistic inflationary model continues.

Magnetic monopoles were a big topic at ISOS I. The report of a possible discovery [3] of one of these cosmological GUT relics sparked an enormous amount of activity, which in contrast to inflation, has largely died away.

Beginning with SU(5) and the possibility of generating the baryon asymmetry of the Universe, unification has been an integral part of early Universe cosmology. At ISOS I, while there were only a few contributions on supersymmetry/supergravity, there was an active session on Kaluza-Klein unification. All of these avenues have been incorporated (more or less) in string theory and in its parent (mother) theory, M-theory.

In the concluding remarks of ISOS I [4], we made some predictions regarding the future of the particle physics/cosmology interface. I quote from that paper, ``That brings us to the future. First, on the theoretical side, it seems likely that inflation, or at least some offshoots of the inflationary paradigm, will continue to be promising avenues to pursue.'' (Given the volumes of publications on inflation in the ensuing years, this is at best an understatement.) ``One of the most promising approaches to unification of all forces seems to be through additional spatial dimensions. An area still in its infancy, cosmology with extra dimensions adds yet another puzzling, but perhaps not unrelated, fact to our list: why are all but three of the spatial dimensions so small? Superstring cosmology opens a Pandora's box of new problems - - whence came geometry, was there an initial singularity, does the Universe after all have a limiting temperature?'' It is remarkable that in the last fifteen years, these are precisely the same questions we continue to ask. To be sure, much progress has been made on the technical side, but cosmology at the Planck time remains a holy grail.

While it is not possible in the context of this contribution in memory of Dave Schramm to completely review the state of the cosmology from the Planck time to BBN, I will attempt to touch on some key issues that are of particular interest today.

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