The Universe Devourer: How World Mergers Explain Dark Energy Without a Cosmological Constant ✛ ✎ ✦
Context
The standard cosmological model with dark matter and dark energy (ΛCDM) successfully describes the large-scale structure of the Universe, yet faces two serious tensions. First, local measurements of the Hubble constant (the Edwin Hubble law) by the Adam Riess team yield H₀ ≈ 72.6 km/s/Mpc, whereas cosmic microwave background data from the Planck satellite indicate H₀ ≈ 67 km/s/Mpc—the so-called 'Hubble tension'. Second, the S₈ parameter, characterizing matter clustering, also shows discrepancies. Recent DESI survey results hint that the dark energy equation of state w may depend on redshift and take values w < –1 at high z. Such behavior is hard to reconcile with an immutable cosmological constant, spurring the development of alternative models.
Methods
The starting point is a minisuperspace description within quantum cosmology, where the spatial volume v(t) ∝ a³(t) serves as the dynamical variable. Instead of the standard term with the cosmological constant Λ, the Hamiltonian incorporates a term responsible for the absorption of 'baby universes' with intensity g. The function f(p) in the generalized Friedmann equation is derived from requiring the Hartle–Hawking wave functions (proposed by Stephen Hawking) to be identical for all colliding universes. The model does not need Λ: exponential expansion arises from world mergers. The parameter g is calibrated against the local H₀ value, after which H(z) and w(z) are numerically computed and compared with observational data, including Type Ia supernovae from the Pantheon+ and Union3 compilations.
Results
The computed $w_f$(z) dependence shows a monotonic decrease from –1.5 as z → ∞ to –1 as z → –1. For H₀ = 72.6 km/s/Mpc, the resulting curve is compared with the w(z) reconstructed from DESI data. The reduced χ² is around 4±0.4, indicating moderate agreement: the model captures the behavior well at z > 0.8 but deviates from data at low z. Including corrections related to spacetime topology changes (described by an analogue of the string coupling constant $G_s$) improves the fit at low z, but at the cost of introducing an extra parameter. For instance, with $G_s$ = –8 using a Padé approximation, the w(z) curve closely approaches the observed one, though the agreement with H(z) data slightly worsens.
Implications
If the universe-absorption mechanism is realized in nature, it radically alters our understanding of dark energy. It ceases to be a fundamental constant or a vacuum property, emerging instead as an effective phenomenon driven by interactions with the multiverse. This scenario aligns with the idea that our Universe is just one among many worlds and naturally explains why the observed dark energy density is so tiny (the cosmological constant problem). Moreover, the model predicts a characteristic w(z) evolution that can be tested by future surveys.
Future development
Future development of the model should include matter when calculating the Hartle–Hawking wave function, providing a physical motivation for the absorption function ˜F(p). It will be crucial to explore connections with microscopic theories, such as quantum gravity or string theory, to derive the effective value of g from first principles. More detailed comparisons with forthcoming data from missions like Euclid and the Roman Space Telescope are also needed.
Impact
The model impacts early Universe cosmology, gravitational theory, and the interpretation of accelerated expansion.
Next steps
Immediate next steps include more precise higher-order G_s corrections to improve low-z agreement, as well as joint analyses with other datasets (e.g., baryon acoustic oscillations). Developing non-perturbative methods for summing topological contributions is also important.
Key open problems
The model is directly tied to the cosmological constant problem (why is Λ so small?), the Hubble tension, and the fundamental question of the role of quantum effects in cosmology. It also resonates with the idea of inflation and the birth of universes from 'nothing' within Big Bang theory.
The knowledge machine's view
This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.
What the work does
The paper proposes a model in which the accelerated expansion of the Universe arises from the absorption of 'baby universes', without a cosmological constant. The authors derived the function f(p) from the condition of identity of Hartle-Hawking wave functions, calibrated the absorption intensity parameter g to the local value of H₀, and numerically calculated H(z) and w(z), comparing them with data from DESI, Pantheon+, and Union3.
Where its strength is
The strength of the work is that it offers a concrete microphysical mechanism for dark energy, deriving acceleration from the process of universe merging rather than postulating it. This yields a predictive model with a single main parameter that can be directly compared with observations.
Where it could go next
- It might be interesting to see how the universe absorption model relates to the idea that dark energy turns on at the birth of galaxies: both approaches link acceleration to processes in the Universe, and comparing them could clarify how universal such a dynamical mechanism is.based on: Dark Energy Turns On When Galaxies Are Born arXiv:2603.23473
- Nearby there is work connecting the expansion of the Universe to thermodynamic effects ('cosmic friction'). Perhaps your model could be reformulated in terms of dissipative processes during universe merging, which would provide an additional physical interpretation of the parameter g.based on: Cosmic Friction: How Disorder Fixes the Universe arXiv:2605.28797
- In the archive there is an analysis emphasizing the uncertainty of the size and expansion of the Universe in quantum cosmology. This could be useful for discussing the status of your predictions: if the volume v(t) is not a classically defined quantity, then comparison with observations requires a more subtle approach.based on: The Universe's Size and Expansion Are Uncertain arXiv:2604.27771
Worth trying
- Check whether the shape of w(z) is preserved when using alternative H(z) data, for example from the BOSS survey or future Euclid data.
- Consider describing universe absorption as a stochastic process and derive an effective equation of state with a noise term.
- Investigate how the model predicts the growth of structures (the S₈ parameter) and whether this could alleviate the S₈ tension.
Why this may matter
If the universe absorption mechanism is realized in nature, dark energy ceases to be a fundamental constant and becomes a consequence of multiverse dynamics. This opens the way to testing the model through future high-precision data on H(z) and w(z), as well as to connections with quantum gravity and string theory.
Nearby works in our archive
- A Dark Deal: How the Universe Reconciles Its Clockssimilarity 0.67
- Dark Energy Turns On When Galaxies Are Bornsimilarity 0.66
- Dark Energy from the Depths of the Atomic Nucleussimilarity 0.65
- Cosmic Friction: How Disorder Fixes the Universesimilarity 0.65
- Dark Matter Decays, the Universe Smooths Outsimilarity 0.65
- The Universe's Size and Expansion Are Uncertainsimilarity 0.64
The closest work in the archive sits at 0.67 by meaning — the usual level for our corpus.
The idea of baby universes traces back to Stephen Hawking's work in quantum cosmology, where he considered the birth of universes from the vacuum. In this model, our Universe literally 'feeds' on other worlds, growing in volume.
The premise of universes interacting with ours echoes Isaac Asimov's novel 'The Gods Themselves', where contact with a para-universe alters physical laws.
Key numbers
- H0: 72.6 km/s/Mpc (adopted local value)
- χ²_red: 4±0.4 (for the baseline model without topological corrections)
- S8: ≈ 0.76 (model prediction)
- w0 (fit): -0.87 (equation-of-state parameter today)
- wa (fit): -0.70 (evolution parameter of w(z))