Foundations of Physics

, Volume 40, Issue 6, pp 629–637

The Non-unique Universe


DOI: 10.1007/s10701-010-9425-3

Cite this article as:
McCabe, G. Found Phys (2010) 40: 629. doi:10.1007/s10701-010-9425-3


The purpose of this paper is to elucidate, by means of concepts and theorems drawn from mathematical logic, the conditions under which the existence of a multiverse is a logical necessity in mathematical physics, and the implications of Gödel’s incompleteness theorem for theories of everything.

Three conclusions are obtained in the final section: (i) the theory of the structure of our universe might be an undecidable theory, and this constitutes a potential epistemological limit for mathematical physics, but because such a theory must be complete, there is no ontological barrier to the existence of a final theory of everything; (ii) in terms of mathematical logic, there are two different types of multiverse: classes of non-isomorphic but elementarily equivalent models, and classes of model which are both non-isomorphic and elementarily inequivalent; (iii) for a hypothetical theory of everything to have only one possible model, and to thereby negate the possible existence of a multiverse, that theory must be such that it admits only a finite model.


Multiverses Godel’s incompleteness theorem Theories of everything Mathematical structures Mathematical logic 

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.TadleyUK

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