"I can't get a picture of this in my head" is not a rebuttal of a physical theory, because there's no reason that our heads must actually be equipped to create pictures of how the fundamental level of reality works.

Agreed, the basic structure of reality may be unvisualizable and otherwise incomprehensible to us. However, a theory is ostensibly a physical explanation, not merely a mathematical summary of the observed data. Reading over Monkeymind's posts, it seems the point he is making is that these theories sort of seem to "feel like" physical explanations, but in the end are "just math."

The question naturally arises, to the newbie at least, of what the difference really is between a mathematical summary of the data we've collected and a mathematical theory of how (by what mechanism) a physical phenomenon occurs.