Many interacting particle systems, such as the totally asymmetric simple exclusion process, lie in the KPZ universality class. This class is characterized by the following critical exponents in one spatial dimension (1 + 1 dimension): the roughness exponent α α = 1 2 , growth exponent β β = 1 3 , and dynamic exponent z = 3 2 . In order to check if a growth model is within the KPZ class, one can calculate the width of the surface: