Deep Metaphysical Question: Does String-Theory Posit Extended Simples?

Deep Metaphysical Question: Does String-Theory Posit Extended Simples It is sometimes claimed that string theory posits a fundamental ontology
including extended mereological simples, in the form either of minimum-sized regions of space or of the strings themselves. But there is very little in the actual theory to support this claim, and much that
suggests it is false. Extant string theories treat space as a continuum, and strings do not behave like simples. Although existing models are not there yet, the string theory program offers the ambition, and at least the potential, for a theory of everything. Should the program eventually succeed, we will have a theory whose interpretation provides the best possible guess at our world’s fundamental ontology. Relatively little philosophical work has addressed string theory thus far, and not much of the extant work has focused on its ontology – which is unsurprising, since the theory has not yet reached a mature stage in either its mathematical form or its
empirical confirmation. But a few remarks have appeared in the philosophical literature addressing
string theory’s relevance to one debate in metaphysics: the possibility or existence of extended simples. Sometimes it is suggested
that (quantum) string theory posits an ontology of extended simples – either the strings themselves, or minimum-sized regions of “quantized” space. Both the popular literature on string theory and some
technical presentations of the theory make these claims appear quite natural. Perhaps there is room for metaphysicians to wrangle over the metaphysical or conceptual possibility of dividing a string, but the fundamental entities of string theory are extended and physically indivisible; so the story goes. String theory is a work in progress, and upon its completion we may indeed find that the final version posits extended simples. But string theory in its present form provides little to no evidence for the existence of extended simples. In the form that has been put forward as
david john baker Does String Theory Posit Extended Simples? a possible theory of everything, string theory is a quantum theory, and as with other quantum theories, its most obvious or literal physical interpretation is almost certainly unsatisfactory. The likeliest guesses
at satisfactory interpretations do not involve extended simples. And even assuming the obvious interpretation, on which quantum string theory has the same ontology as the classical version of string theory, this ontology does not include extended simples. To support these claims, I will of course need to present some details of the theory. In Section 2 I will do so, hopefully avoiding onerous
technicalities in favor of conceptual clarity while doing justice to the facts. I will then consider in turn the claim that strings are extended
simples (Section 3) and the claim that string theory posits minimumsized regions of space with no proper parts (Section 4). The former rests on an untenably classical understanding of string theory, while
the latter is supported only by the speculative or analogical remarks of some physicists. Neither the theory itself nor the likely direction of its future development bears out these remarks, which in some instances arise from a simple conflation of the detectable and the real. In present-day string theories, spacetime (if it exists at all) is continuous.