Question: what are you planning to do with your model???

Julian Onions answered on 20 Nov 2014:

The model – which is in a computer – is the sort of thing you can look at and see how it looks. Does it look like the real universe? If so we have made the right sort of model in the computer. If not – we have work to do. So mostly I examine the model for various things and see if those things are the same as the real one. If not, I get the computer to make a new one!