Version History

Click the history icon to see version history for a TREF block.

Article with Version History

This article has been updated 3 times. Hover over the TREF icon and click the history button (rotate icon) to see all versions.

The Speed of Light

The speed of light in a vacuum is exactly 299,792,458 meters per second.

This value was fixed by the SI system in 1983 and is used to define the meter.

How It Works

  1. Each version of an article gets a unique SHA-256 ID
  2. A history.json file tracks all versions
  3. The wrapper fetches history from data-history attribute
  4. Popup shows version list with dates and IDs

history.json format:

{
  "current": "sha256:abc123...",
  "versions": [
    { "v": 3, "id": "sha256:abc...", "date": "2026-01-08" },
    { "v": 2, "id": "sha256:def...", "date": "2026-01-06" },
    { "v": 1, "id": "sha256:ghi...", "date": "2026-01-04" }
  ]
}