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arxiv: 1907.07344 · v1 · pith:MSTLPEGHnew · submitted 2019-07-17 · 🌀 gr-qc

Wormhole Modeling Supported by Non-Exotic Matter

Pith reviewed 2026-05-24 20:32 UTC · model grok-4.3

classification 🌀 gr-qc
keywords wormholef(R) gravityenergy conditionstraversable wormholeshape functionmodified gravitynon-exotic matter
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The pith

A logarithmic shape function for wormholes in f(R) gravity permits non-exotic matter to satisfy energy conditions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The authors construct traversable wormhole solutions in f(R) gravity using the form f(R) equal to R minus a term involving the Ricci scalar raised to a power between zero and one. They employ a specific shape function previously introduced by the same authors to define the wormhole geometry. Analysis shows that the resulting stress-energy tensor satisfies the energy conditions, indicating that ordinary matter can support the wormhole. This matters because in standard general relativity, wormholes typically require exotic matter that violates energy conditions, making such models unphysical.

Core claim

In f(R) gravity with f(R)=R−μRc(R/Rc)p where 0<p<1, the shape function b(r)=r log(r+1)/log(r0+1) leads to stress-energy components that fulfill the null, weak, strong and dominant energy conditions, thereby modeling traversable wormholes supported by non-exotic matter.

What carries the argument

The shape function b(r)=r log(r+1)/log(r0+1) combined with the f(R) modification that alters the effective stress-energy requirements.

Load-bearing premise

The specific logarithmic shape function generates stress-energy components meeting the energy conditions under the chosen f(R) gravity model.

What would settle it

Demonstrating a violation of the null energy condition at the wormhole throat for this shape function and f(R) form would disprove the support by non-exotic matter.

Figures

Figures reproduced from arXiv: 1907.07344 by Gauranga C. Samanta, Nisha Godani.

Figure 1
Figure 1. Figure 1: Case 2: Plots for Density, NEC, DEC, 4 & ω with f(R) = R + αRm 10 [PITH_FULL_IMAGE:figures/full_fig_p010_1.png] view at source ↗
read the original abstract

In the present paper, the modelling of traversale wormholes, proposed by Morris \& Thorne \cite{morris1}, is performed within the $f(R)$ gravity with particular viable case $f(R)=R-\mu R_c\Big(\frac{R}{R_c}\Big)^p$, where $\mu, R_c>0$ and $0<p<1$. The energy conditions are analyzed using the shape function $b(r)=\frac{r\log(r+1)}{\log(r_0+1)}$ defined by Godani and Samanta \cite{godani} and geometric nature of wormholes is analyzed.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. The paper models traversable wormholes in f(R) gravity with the specific viable case f(R)=R−μRc(R/Rc)^p (μ,Rc>0, 0<p<1), using the shape function b(r)=r log(r+1)/log(r0+1) from prior work. It analyzes the energy conditions to claim that the wormholes are supported by non-exotic matter and examines the geometric nature of the wormholes.

Significance. If the central claim held, the work would provide an explicit construction of traversable wormholes in this f(R) theory supported by ordinary matter satisfying the energy conditions. The result does not hold, however, because the underlying geometry is invalid.

major comments (1)
  1. [Abstract] Abstract (shape function definition): The given shape function b(r)=r log(r+1)/log(r0+1) violates the flaring-out condition required by the Morris-Thorne traversable wormhole metric. Its derivative evaluates to b'(r)=(1/log(r0+1)) * [log(r+1) + r/(r+1)], so that b'(r0)=1 + [r0/(r0+1)]/log(r0+1) >1 for any r0>0. Morris-Thorne wormholes require b'(r0)<1 to ensure (b−r b')/b^2 >0 at the throat. This geometric defect is independent of the choice of f(R) parameters or stress-energy tensor and renders the proposed model invalid.
minor comments (1)
  1. [Abstract] The abstract states that energy conditions are analyzed but supplies no explicit substitution, no verification that the inequalities hold after inserting the shape function and f(R) form, and no discussion of how the free parameters μ, Rc, p, r0 are chosen.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thorough review and for identifying an important issue with the shape function used in our manuscript. We address this comment below.

read point-by-point responses
  1. Referee: [Abstract] Abstract (shape function definition): The given shape function b(r)=r log(r+1)/log(r0+1) violates the flaring-out condition required by the Morris-Thorne traversable wormhole metric. Its derivative evaluates to b'(r)=(1/log(r0+1)) * [log(r+1) + r/(r+1)], so that b'(r0)=1 + [r0/(r0+1)]/log(r0+1) >1 for any r0>0. Morris-Thorne wormholes require b'(r0)<1 to ensure (b−r b')/b^2 >0 at the throat. This geometric defect is independent of the choice of f(R) parameters or stress-energy tensor and renders the proposed model invalid.

    Authors: We agree with the referee's calculation. The derivative b'(r) is indeed as stated, leading to b'(r0) > 1 for any r0 > 0. This violates the flaring-out condition b'(r0) < 1 required for the Morris-Thorne wormhole to be traversable. We acknowledge that this renders the specific model presented in the manuscript invalid. We will revise the manuscript by adopting a shape function that satisfies the flaring-out condition, such as one from the literature that meets b'(r0) < 1, and will re-evaluate the energy conditions and geometric properties accordingly. revision: yes

Circularity Check

0 steps flagged

No circularity detected in derivation chain

full rationale

The paper adopts an ansatz shape function b(r) from prior self-work and a standard f(R) form, then computes the resulting stress-energy tensor components and checks energy conditions. No step equates a claimed prediction or first-principles result to its own inputs by construction; the energy-condition analysis follows directly from the Einstein equations modified by f(R) and the given metric functions. The self-citation supplies only the choice of coordinate function b(r), which remains an external modeling input rather than a derived output. No fitted parameters are renamed as predictions, and no uniqueness theorem or ansatz is smuggled via self-citation to force the final claim.

Axiom & Free-Parameter Ledger

4 free parameters · 2 axioms · 0 invented entities

The claim rests on the Morris-Thorne metric ansatz, the chosen f(R) functional form, and the authors' earlier shape function. No new physical entities are introduced. Free parameters are the model constants μ, Rc, p and the throat radius r0.

free parameters (4)
  • μ
    Dimensionless parameter controlling the deviation from GR in the f(R) model.
  • Rc
    Characteristic curvature scale in the f(R) model.
  • p
    Exponent with 0 < p < 1 in the f(R) model.
  • r0
    Throat radius appearing in the shape function definition.
axioms (2)
  • domain assumption The spacetime is described by the Morris-Thorne traversable wormhole metric.
    Standard ansatz invoked for all wormhole modeling in the paper.
  • domain assumption The f(R) model with 0 < p < 1 is a viable modified gravity theory.
    Background assumption taken from prior f(R) literature.

pith-pipeline@v0.9.0 · 5624 in / 1501 out tokens · 26581 ms · 2026-05-24T20:32:49.419881+00:00 · methodology

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Lean theorems connected to this paper

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Reference graph

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