[sm666]

I think one first has to define what kind of zero we are talking about. you have the integer value zero, and the real value. The former I can show exists simply by counting, that being if you have an apple and take it away you have zero apples, as they are whole objects.

The real value zero relates more closely to physical values - the measure of time, the measure of energy, distance, etc. In this case I really can't imagine actually having zero, as in each case you can continue to sub divide the intervals for a long as you wish, getting ever smaller and smaller values, but never zero. The funny thing about this though, is the idea of quantum mechanics of quantization, which turns these values again into a counting format - much like binary, you have a zero or a one, something or nothing because there is a limit to how small you can make something (i.e on the Planck scale). Seeing as we really have no concrete idea as to why things are quantized at the scale they are, I'm not sure there is really much to be said of "real zero" either.