> This is even difficult to do when what you're trying to model is not the physical world, but a computer system. Indeed. A couple of days ago, somebody posted

> This is even difficult to do when what you're trying to model is not the physical world, but a computer system. Indeed. A couple of days ago, somebody posted a fascinating image of memory latency (http://www.bitmover.com/mem_lat.jpg http://www.bitmover.com/mem_lat.jpg) in a comment here. Getting to a model of a computer system which captured all the subtleties in this graph isn't easy - and this is only one aspect of real computer behavior. Abstractions and approximations are extremely important in science, computer science included, but I am often disappointed by how little thought is given to the implications of these approximations. In comparison, getting excited about floating point error is much easier. This is not a criticism of Sussman or his talk in any way, but just an observation on many computer engineering and computation papers.