Simple

The Universe Around Us Turned Out to Be More Curved Than We Thought

Original: "Backreaction and the Role of Spatial Curvature in the Cosmic Neighborhood"
arXiv:2605.05454v1 · 2026-05-06 · CC BY 4.0 · ⏱ 1 min · Cosmology General Relativity
The space around us isn’t a smooth sheet—it’s a bumpy blanket, and its contribution to expansion is 10% and isn’t weakening.
Abstract

Scientists have, for the first time, measured how density, expansion rate, and spatial curvature are distributed in our nearby Universe. They found that on scales up to 300 million light-years, curvature plays a noticeable role (about 10%), while small-scale inhomogeneities hardly matter. It's like how the shape of a bowl guides marbles more than tiny scratches do. What else is hidden in the structure of our cosmic neighborhood?

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Under the influence of gravity, space dents like a stretched blanket: galaxies and their clusters create dips and bumps, and the main contribution to curvature comes from invisible dark matter (a discovery linked to Vera Rubin). Astronomers mapped local space using the motions of thousands of galaxies (from the Cosmicflows-4++ catalog, accounting for redshift and peculiar velocities) via computer simulations.

It turns out that curvature contributes roughly 10% to expansion and doesn’t taper off over distances up to a billion light-years. This contradicts the standard model, which, relying on the cosmic microwave background, assumes a smooth universe. Local bumps distort dark energy measurements by tens of percent—meaning we could be way off in our estimates. It’s astonishing that we live inside such a 'dent,' nested within an even larger void, like a cosmic matryoshka doll. Accounting for this relief will help refine the cosmic picture started by Edwin Hubble and Georges Lemaître.

🎯 Our universe resembles a matryoshka doll: we live inside a 'bubble' surrounded by a 'wall' of superclusters, which in turn is embedded in a giant void.

\Omega_M^{\mathcal{D}} + \Omega_\Lambda^{\mathcal{D}} + \Omega_R^{\mathcal{D}} + \Omega_Q^{\mathcal{D}} = 1
Ω_M — fraction of ordinary and dark matter, Ω_Λ — fraction of dark energy (cosmological constant), Ω_R — fraction of spatial curvature, Ω_Q — fraction of kinematic backreaction.
Scientists
Alan GuthAndrei LindeGeorges LemaîtreJames PeeblesAdam RiessBrian Schmidt
Tags
spacetime curvature expansion of the universe dark matter dark energy galaxy galaxy cluster redshift numerical simulation Standard Model gravity cosmic microwave background
Laws
Friedmann equationsHubble's lawgravitational lensingNoether's theoremPlanck's lawequivalence principle
Original: arXiv:2605.05454v1 · CC BY 4.0 · bridge42worlds