Cosmological simulations evolve the initial density fluctuations in the Universe from early times, when the perturbations are still linear, to some later time (often today) when the perturbations are highly non-linear. Early cosmological simulations were predominantly n-body simulations that incorporated only the physics of gravity into the computation of structure evolution. Since the early 90s more complete models of physics have been incorporated into the simulations; gas dynamics, stellar formation, and radiative transfer are prime examples of such physics.

There is much science that goes into the development of a robust cosmological simulation code. Such endeavors are often interdisciplinary, requiring sophisticated computer science techniques and a creative knowledge of computational algorithms. The writing of cosmological simulations is not, however, astrophysics! Astrophysics sets the initial conditions, and astrophysics must interpret the results of the simulation. This website concentrates on the astrophysical aspects of the simulation. We do not delve into the algorithmic details and, instead, think of these simulations as astoundingly complicated boxes with cranks attached. The crank is turned -- and structure emerges!