(Physics engine: computing the interaction of things located in time and space)
Obviously, it is impossible to know the nature of the world we inhabit while being entirely caught up inside it: the basic trouble with epistemology is that the world only shows us phenomena (Husserl), or, more basically but inaccurately: discernible differences, i.e. information, and not its structure itself. Thus, we cannot know if anything beyond the phenomena or the information exists. And if it does, what do we mean by "existence"?