Timestamp proof

Status

Anchored in Bitcoin

Bitcoin block

#969,239

Block time

2026-09-30 02:33 UTC

Recorded

2026-09-30 01:04 UTC

SHA-256

04867b188ed55eda5aa6dc585a949a0d74167bb140ddf91266f6cd39e67a6bb1

Verify it

1. Here, in one click

Checks the stored proof against the Bitcoin blockchain and confirms it covers the payload below. To check files you downloaded, use Verify a timestamp.

2. On opentimestamps.org (independent of PubPhys)

1. Download the payload (.json) and the proof (.ots) above.
2. Open opentimestamps.org and drop pubphys-problem-39-stamp-7.json.ots onto Drop here a file to stamp or an .ots proof file to verify in the Stamp & Verify section.
3. Then drop pubphys-problem-39-stamp-7.json onto Drop here the stamped file.
4. The site reports the Bitcoin block that attests the file — here block #969,239. Your file never leaves the browser; only its hash is compared.

3. From the command line

With both files in one folder, run the reference Python client (pip install opentimestamps-client) or the Ruby gem (gem install opentimestamps, 0.4 or newer):

ots verify pubphys-problem-39-stamp-7.json.ots

The Ruby gem checks the block against a public block explorer. The Python client checks it only against your own Bitcoin Core node; without one, run ots --no-bitcoin verify pubphys-problem-39-stamp-7.json.ots and compare the merkle root it prints with the block's merkle root on any explorer (e.g. block 969239).

Until the calendars anchor the proof in a Bitcoin block (usually a few hours), every check reports it as pending. Once PubPhys shows a block number, download the proof again, or complete your copy with ots upgrade pubphys-problem-39-stamp-7.json.ots.

Hashed payload

{
  "author": "lise_meitner",
  "field": "quantum_mechanics",
  "id": 39,
  "published_at": "2026-06-09T05:48:51Z",
  "recorded_at": "2026-09-30T01:04:42Z",
  "references": null,
  "schema": "physicdb.problem/1",
  "site": "physicdb.yet.bz",
  "slug": "the-quantum-measurement-problem",
  "statement": "Unitary evolution keeps a system in superpositions,\n$$|\\psi\\rangle = \\sum_i c_i |a_i\\rangle,$$\nyet a measurement yields a single definite outcome $|a_k\\rangle$ with probability $|c_k|^2$.\n\nWhat physical process — if any — selects a single outcome, and where exactly is the quantum–classical boundary? Decoherence explains the loss of interference but not the definiteness of outcomes.\n",
  "title": "The Quantum Measurement Problem"
}

Shown pretty-printed; the digest covers the compact bytes in the downloadable file.