  Renormalization group theory is a powerful and intriguing technique with a
wide range of applications. One of the main successes of renormalization group
theory is the description of continuous phase transitions and the development
of scaling theory. Most courses on phase transitions focus on scaling and
critical exponents, while less attention is paid to universality,
renormalization group flow, and the existence of a unique fixed point, which
are the ultimate reasons why scaling theory is so effective in describing
continuous phase transitions. We use a combination of Monte Carlo simulations
and real space renormalization group theory to determine the renormalization
group flow and to show the existence of a universal fixed point in the context
of the ferromagnetic Ising model.
