You might think simulating the entire Universe is difficult, and it is, but not for the reasons you would think.  The Physics is actually somewhat straightforward.  We know the math behind star formation, Gravity, and fluid dynamics, and throwing in a few other effects is not too bad.   The hard part is finding a computer powerful enough to do the calculations in a reasonable amount of time. Think about it.  Imagine having a universe of 100 Billion ‘particles’ used for a simulation.  Each particle has a starting point, and that it pretty easy to do.  But then for every...