Abstract
 
 Most technologically useful materials are polycrystalline, composed of 
 many small crystallites called grains separated by interfaces called 
 grain boundaries.  These grain boundaries play a role in many material 
 properties, for example conductivity and fracture toughness, and across 
 many scales.  Preparing arrangements or distributions of boundaries 
 suitable for a given purpose is a central problem in materials.  To 
 control it we must understand grain growth.  For example, to what 
 extent is grain growth like or unlike the growth of soap bubbles?
 
 In this expository talk we discuss some of the scientific challenges we 
 encounter in the investigation of these issues.  What are the 
 strategies for determining interfacial energy?  Can we simulate large 
 grain networks?  We address the mesoscale simulation of large systems. 
 What is the 'answer' of such a simulation? This is a very pregnant 
 question. This is joint work with Florin Manolache, Jeehyun Lee, Irene 
 Livshits, Anthony Rollett, and Shlomo Ta'asan.