  A fundamental physical principle that has consequences for the topology of
space-time is the principle of Einstein-Weyl causality. We show here that this
may have implications on quantum mechanics, as well. Borchers and Sen have
rigorously investigated the mathematical implications of Einstein-Weyl
causality and shown the denumerable space-time Q^2 would be implied. They then
imbedded this space in a non-denumerable space but were left with important
philosophical paradoxes regarding the nature of the physical real line E, e.g.,
whether E = R, the real line of mathematics. Alternatively, their initial
result could suggest a constructible foundation. We have pursued such a program
and find it indeed provides a dense, denumerable space-time and, moreover, an
interesting connection with quantum mechanics.
