Accounting for the large radial tension in Morris-Thorne wormholes

Abstract

It is well known that a Morris-Thorne wormhole can only be held open by violating the null energy condition, physically realizable by the use of "exotic matter." Unfortunately, even a small or moderately-sized wormhole would have a radial tension equal to that of the interior of a massive neutron star. So outside a neutron-star setting, such an outcome is problematical at best, calling for more than an appeal to exotic matter whose introduction had a completely different objective and with possibly different outcomes. The purpose of this paper is to account for the enormous radial tension in three ways: (1) directly invoking noncommutative geometry, an offshoot of string theory, (2) appealing to noncommutative geometry in conjunction with $f(R)$ modified gravity, and (3) determining the possible effect of a small extra dimension.