The difference between theoretical and simulation activities can be explained if we analyse the different stages of a field in physics. The theoretical part comes to play when we are trying to understand how an specific phenomena happens. In these early stages, the theoretical activities and the experimental activities come to play. Once a mathematical model has been built (once the theoretical activities have been done) then we can apply them in simulation. Simulations can be used to test the mathematical model built from the theoretical activities or it can be used later once the model has been considered a matured field.