Gerard 't Hooft (Nobel Laureate 1999) may disagree with John?
"...The standard theory of general relativity, which describes the gravitational forces in the macroscopic world, approaches a similar degree of perfection. Einstein’s field equations are local, and here, cause also precedes effect in a local fashion. These laws, too, are completely unambiguous.
But how can we combine the Standard Model with general relativity? Many theorists appear to think that this is just a technical problem. But if I say something like "quantum general relativity is not renormalizable", this is much more than just a technicality. Renormalizability has made the Standard Model possible, because it lets us answer the question of what happens at extremely tiny distance scales. Or, more precisely, how can we see that cause precedes effect there? If cause did not precede effect, we would have no causality or locality - and no theory at all..." http://physicsweb.org/articles/world/18/12/2