Is 'dark matter' made entirely of the gravitational field?

Abstract

We argue that part of 'dark matter' is not made of matter, but of the singular world lines and world surfaces in the solutions of Einstein's vacuum field equation Gμν = 0. Their Einstein–Hilbert action governs, in a slightly modified form, also their quantum fluctuations in a partition function formed from a sum over all line and surface configurations. For world surfaces, the Einstein–Hilbert action coincides with that of closed bosonic 'strings' in four spacetime dimensions, which appear here in a new physical context.