IFT-UAM/CSIC-06-01\
[**hep-th/0601003**]{}\
January $1$st, $2006$

[^1]

[Tomás Ortín]{}

[*Instituto de Física Teórica UAM/CSIC\
Facultad de Ciencias C-XVI, C.U. Cantoblanco, E-28049-Madrid, Spain*]{}\
E-mail: [Tomas.Ortin@cern.ch]{}

[**Abstract**]{}

> In the recent times a lot of effort has been devoted to improve our knowledge about the space of string theory vacua (“the landscape”) to find statistical grounds to justify how and why the theory selects its vacuum. Particularly interesting are those vacua that preserve some supersymmetry, which are always supersymmetric solutions of some supergravity theory. After an general introduction to how the pursuit of unification has lead to the vacuum selection problem, we are going to review some recent results on the problem of finding all the supersymmetric solutions of a supergravity theory applied to the $N=4,d=4$ supergravity case.

Introduction: Unification and the Landscape
===========================================

Unification has been one of the most fruitful guiding principles in our search for the fundamental components and forces of the Universe. It is, however, more than just a wish or a prejudice that has produced important results for a while: it is indeed a logical necessity for the human mind to understand the Universe: the history of Physics could be written as the history of the process of 