A very little bit of group theory

One simple example of a group, are the symmetries of a triangle. You can rotate the triangle, or flip it. This is called a discrete group.

Another simple group is the symmetries of the circle. This is a continuous group and is called U(1)

The group SU(2) is basically the group of rotations of 3 dimensional space. The group SU(3) is more challenging to describe.

# David Kastor

COSMOS to HUMANITY, Spring 2008

Lecture 2 , slide 21