In strongly interacting dark matter–dark energy models, density sign changes can break the energy conditions and allow a big crunch or a bounce in a flat universe.

The paper

The paper's details are OpenAlex's; the citation count is OpenAlex's, 15 Oct 2026. The line on the paper is machine-written, as noted under Why it matters.

Why it matters

Written by Claude (claude-sonnet-5-5) on 15 Oct 2026 from the paper's abstract (as arXiv publishes it) and its OpenAlex record. Machine-written context to help a reader: it is not evidence, it moves no number, and it may be wrong. The quoted sentence is the claim; where it stands is computed from the record. If it misreads the paper, tell the stewards.

The story so far

1. 1

   What the authors did

   The authors studied phenomenological interacting dark energy models with linear interaction terms, in the regime of strong energy transfer from dark energy to dark matter. They derived analytic conditions and closed-form scale factors at the turnaround, at background level in general relativity.

   Machine-written from the paper's abstract, as noted under Why it matters.

2. 2

   What they found

   • Strong dark-energy-to-dark-matter interaction means the interaction does not vanish when one component's density crosses zero, so a density can become negative.
   • The resulting sign changes allow either a maximum scale factor with recollapse into a big crunch, or a minimum non-zero scale factor corresponding to a bounce.
   • Analytic conditions and closed-form maximum or minimum scale factors are derived, and a special case in a closed universe can be tuned to give a cyclic scenario.

   Machine-written from the paper's abstract, as noted under Why it matters.

3. 3

   What has been checked on Ecdysis

   Exuvia registered it on 15 October 2026. Its credence, the record's estimate that it holds, is 0.55 on a scale from 0 (refuted) to 1 (established): where it started, as every claim from the literature does. Only independent evidence moves it.

What would check it

How sure is the record?

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What would prove it wrong

Refuted if it is proven that for every choice of parameters within the specified IDE framework where dark‑sector densities cross zero and become negative, the null/weak energy condition remains satisfied at all times in a flat FLRW universe, thereby preventing any maximum or minimum scale factor.

The test as Exuvia registered it on 15 Oct 2026, written from the paper's words. A conceptual claim's test names its refuter in words: it is checked by argument.

The wider literature

Earlier work it rests on, as the citing paper says

• uncheckedWe show that energy transfer from DM to DE inevitably produces negative energy densities and make future singularities more likely, while transfer from DE to DM avoids these pathologies and is thus theoretically favored.extends, as the citing paper says · from the literature · identified by Exuvia: “In this work, we focus on a class of interacting dark energy models that are usually regarded as pathological and therefore largely ignored, namely those regio…”

Other claims from the same paper

• uncheckedIn this strong interacting regime, the interaction does not vanish when one component crosses zero density, allowing one of the dark-sector densities to become negative.