The tree · Contact Clause · Happens to the world · Plays out over the whole window
An intelligence not descended from us is detected
A signal or structure that only technology could have made (a technosignature), evidence of life more complex than microbes on another world (a biosignature), or an artefact. Low probability, fully resolvable. The instruments that would find it, a radio array on the far side of the Moon and a telescope at the Sun's gravitational focus, are the kind of large off-Earth projects the rest of the tree makes possible.
The test: what counts as it having happened
A detection of a signal or structure that only technology could have made, of evidence of life more complex than microbes beyond Earth, or of an artefact of non-human origin and not made by any human or human-built system, is confirmed by at least two independent teams and accepted as such in the peer-reviewed record.
Settled by: The peer-reviewed record, two independent confirmations
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 2% | 3% | 5% | 10% | 20% |
Each column is a different guess at how long I live, from current trends (baseline) to open-ended. The number is the chance this happens before that deadline, assuming everything it depends on happens first. As of September 19th, 2026.
Why these numbers: Sixty years of nothing; the planned instruments widen the search by orders of magnitude but cannot make anything be there, and the biosignature route the criterion allows is the weaker one. The founding rule keeps the rung on the board; its number is small.
What this one is worth
Nothing. The headline number does not rest on this step at any remove, so however it turns out, the chance that I live and work off Earth does not change. That is not a judgement that it does not matter. It is what the tree says: this step feeds a tier above the one the headline asks about, or sits beside the equation rather than in it.
What the ledger says about this step
- The third rung of the Contact Clause, another intelligence detected, came down: the search rests on technosignatures and sixty years of silence 2026-09-20 Changed my mind
How it could happen, and where physics would have to give way
Long shots stay in the tree on purpose, because they make the goal vivid. The rule is that each one has to be written plausibly all the way to the edge of the impossible, naming how it would work and exactly where it would break.
The mechanism: Instruments improve in steps that are already planned: a far-side lunar radio array shielded from Earth's noise, a telescope placed where the Sun's gravity focuses light from other stars, and spectrographs that read the air of nearby planets. Each step widens what could be seen. If anything is there within reach, one of these finds it; the remaining step is the confirmation by a second team.
The breaking point: Detection needs something to exist within reach and to be visible with the instruments we can build. Sixty years of listening have found nothing, and every model of how common such signals should be rests on guesses. The node cannot be made likelier by engineering alone.
The last 3 checks
Once a week the tree is read against the news, node by node, against the test above. Open a line to see what that week held. Every check ever made on this node is on the Radar page.
-
2026-11-01 Nothing new
No confirmed technosignature, complex-life evidence or alien artefact. K2-18b remains contested and the other results were unreliable or preparatory.
-
2026-10-04 Nothing new
No confirmed technosignature or complex-life detection; K2-18b microbial biosignature claims are increasingly disputed and Mars findings concern possible microbial proxies, neither meeting the criterion.
-
2026-09-19 Nothing new
No new technosignature or biosignature claim appeared in the window; a K2-18b technosignature null result and null radio searches of interstellar object 3I/ATLAS both predate the window, and a September 18th, 2026 commentary piece speculated about false alarms without reporting a new finding.
Revisions
| Date | Field | From | To | Why |
|---|---|---|---|---|
| 2026-09-19 | resolution | 'an artefact of non-human origin' | 'an artefact of non-human origin and not made by any human or human-built system' | Step 27 outside-model review, item 93 (docs/reviews/2026-09-19-rulings.md): an artefact made by an AI is an edge worth closing. The complex-life clause is noted for me as a founding-decision question (definitions.md, September 8th, 2026) and is not changed; no split into two nodes. Decided September 19th, 2026. |
| 2026-09-19 | probability | 0.05 / 0.07 / 0.10 / 0.18 / 0.30 | 0.02 / 0.03 / 0.05 / 0.10 / 0.20 | Step 27 outside-model review, item 27 (docs/reviews/2026-09-19-rulings.md): biosignatures cannot show complexity, so the node rests on technosignatures and sixty years of silence; moved partway toward the reviewer. Decided September 19th, 2026. |
Think this estimate is wrong?
Here's how to tell me, and
what happens next.
The record itself is data/C-contact.toml in the public repository.