I’m not sure in what is the best way approach this topic in-order to stay within the forum guidelines but I hope I’ve done so. From the recent moderator actions, this topic it is too far removed from the philosophy of mathematics to be part of that thread. The basic question is whether existence is purely physical and precisely at the present (constrained by time) or whether we can expand the notion of existence to include such things as: ideas and possible future events. This relates to the mathematics thread, in that, math is not physical. It is an idea of our mind and hence cannot exist in the physical world. However, Plato took a different notion of existence and for instance considered the form of a triangle to be more real than the imperfect material representations of triangles. One analogy Plato used to support this view in, “The Republic", was the, “Allegory of the Cave”. In this analogy he compared our sense understanding of the world to shadows on the cave. These shadows let us know something of the object but hid the true form of the object. Plato said that if all we saw were the shadows on the wall then we may come to believe that they represent reality rather than the object which casts the shadows. Well generally our language is such that, for something to exist, it must be present and it must be observable (for if something existed in the past we say it no longer exists and if we can’t observe something we dismiss it as nonsense). However, Plato’s view of reality is not completely foreign to the field of physics. For instance some models of physics includes hidden variables such as dimensions we cannot see and particle physics considers an observed object to be a superposition of eignstates (or at a lower level a super position of Feynman Diagrams). Yet prior to measurement these states only define the probabilities of future measurements. That is: each state represents a possible future measurement and; no state is actually realized until we take a measurement. In other words, all possible measurements existed, a prior, to any actual realization. I am more inclined to take the Material view of reality yet this seems to a degree a Symantec choice, in that, I know thoughts and ideas exist in my mind, yet I can’t touch or see them. The best I can say is that it is epiphenomenal. Similarly with quantum mechanics, I dismiss it as merely a tool to make predictions, yet there are many people who believe that models of physics represent reality. Thus, the most I know on this topic is, my own ignorance.