Pith Number

pith:UGSX3ABX

pith:2026:UGSX3ABX5ZFBJRQ3RGC55KNC63

not attested not anchored not stored refs pending

A First Observational Assessment of Cosmic Backreaction Over an Extended Redshift Range

S. M. Koksbang

New observable combination delivers first direct constraints on cosmic backreaction over an extended redshift range.

arxiv:2604.11249 v2 · 2026-04-13 · astro-ph.CO

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\usepackage{pith}
\pithnumber{UGSX3ABX5ZFBJRQ3RGC55KNC63}

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Record completeness

1 Bitcoin timestamp

2 Internet Archive

3 Author claim open · sign in to claim

4 Citations open

5 Replications open

✓ Portable graph bundle live · download bundle · merged state

The bundle contains the canonical record plus signed events. A mirror can host it anywhere and recompute the same current state with the deterministic merge algorithm.

Claims

C1strongest claim

yielding the first direct constraints on the total cosmic backreaction in our Universe over a significant redshift range. The constraints are consistent with vanishing backreaction within one standard deviation. However, the constraints are fairly weak and significant backreaction cannot be ruled out.

C2weakest assumption

The novel combination of redshift, distance, and expansion rate observables introduced in the companion preprint accurately isolates the backreaction signal without large systematic biases or hidden cosmological assumptions.

C3one line summary

First direct constraints on total cosmic backreaction over a significant redshift range are consistent with vanishing backreaction within 1 sigma but are too weak to exclude meaningful backreaction.

Cited by

1 paper in Pith

Backreaction and the Role of Spatial Curvature in the Cosmic Neighborhood

Receipt and verification

First computed	2026-07-02T01:17:31.045480Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

a1a57d8037ee4a14c61b8985dea9a2f6e398731c75fef6a4921b52c56a39bdcf

Aliases

arxiv: 2604.11249 · arxiv_version: 2604.11249v2 · doi: 10.48550/arxiv.2604.11249 · pith_short_12: UGSX3ABX5ZFB · pith_short_16: UGSX3ABX5ZFBJRQ3 · pith_short_8: UGSX3ABX

Agent API

Resolver JSON Graph JSON Events JSON Schema Signing key

Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/UGSX3ABX5ZFBJRQ3RGC55KNC63 \
  | jq -c '.canonical_record' \
  | python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: a1a57d8037ee4a14c61b8985dea9a2f6e398731c75fef6a4921b52c56a39bdcf

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "0dec45a601a4b0dde595bde387350066e6d85ccf9402ef0ead4e70156c562324",
    "cross_cats_sorted": [],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "astro-ph.CO",
    "submitted_at": "2026-04-13T09:59:16Z",
    "title_canon_sha256": "f09a0b4808fc51f1551e2390b900a3d408a7dc4aead2ef0adafad02e9052869b"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2604.11249",
    "kind": "arxiv",
    "version": 2
  }
}