Is string theory a theory of strings?

TL;DR

This paper explores the duality between type IIA and heterotic string theories, revealing a solitonic membrane in heterotic theory that becomes fundamental in type IIA, suggesting type IIA may be a membrane theory.

Contribution

It demonstrates the existence of a heterotic solitonic membrane that maps to a fundamental membrane in type IIA, proposing a membrane-centric view of the theory.

Findings

A heterotic solitonic membrane becomes a fundamental membrane in type IIA.

Type IIA string theory may fundamentally be a membrane theory.

Dualities relate solitonic solutions to fundamental objects across theories.

Abstract

Recently a great deal of evidence has been found indicating that type IIA string theory compactified on K3 is equivalent to heterotic string theory compactified on T^4. Under the transformation which relates the two theories, the roles of fundamental and solitonic string solutions are interchanged. In this letter we show that there exists a solitonic membrane solution of the heterotic string theory which becomes a singular solution of the type IIA theory, and should therefore be interpreted as a fundamental membrane in the latter theory. We speculate upon the implications that the complete type IIA theory is a theory of membranes, as well as strings.