© Wikimedia Commons, Creative Commons 3.0 Unported License. Author: MissMJ, 27 June 2006.
The particles of the Standard Model—six quarks, six leptons, and four force carriers—fit together in a sort of periodic table, as we learned in Unit 1. String theorists would like to believe that the structure of this table arises from the geometry of space itself. For instance, the basic elementary particles could arise as the lowest energy configurations of strings on the six compact dimensions discussed in this unit. (Unit: 4)