Abelian gerbes play a ubiquitous role in string and supergravity theories. It is conjectured that non-abelian gerbe theories exist, but a satisfactory explicit construction of such a theory has not yet been achieved. Inspired by the possibility that a non-abelian theory of gerbes may be possible on non-conventional spacetimes, I will consider a toy model on a lattice that allows one to make some progress in this problem. In this talk, I will show how abelian gerbe theories may be described naturally on the lattice. I will outline a non-abelian generalisation and show how, under dimensional reduction, such theories give rise to lattice Yang-Mills.

In this seminar, I will give an introduction to a series of ideas which suggest that many aspects of quantum fied theories, including the celebrated N=4 super Yang-Mills, may be most simply understood in terms of a dual theory in twistor space. No previous knowledge of string theory or twistor theory will be assumed.

This is the first lecture of a short course on non-geometric backgrounds. For more information on the course and the schedule, please visit http://www.strings.ph.qmw.ac.uk/index.htm and follow the link to the Graduate Program in String/Field Theory.