Research area / Deep-Time Signals
Deep-Time
Signals
Signals that cross deep time: from the past to us, which archaeology reads, and from us to whoever comes after. SETI sits inside this problem, not beside it.
Central question
How does technological information survive deep time, and under what conditions can an unknown intelligence recover it?
01 / Premise
Archaeology is the search for origins
Defined most broadly, archaeology is the search for origins across all systems and studies. Galactic archaeology and the other origin studies astronomers pursue are archaeology in that broad sense.
Its core, as a discipline, is narrower: the development of technological species, and how to reconstruct their history from the traces they leave.
02 / Two directions
From the past to us. From us to the future.
Archaeology and SETI are two directions of the same problem.
Past → present
Reconstruct processes from the traces that survive.
Present → future
Construct traces capable of carrying information to future observers.
Process
Signal
Preservation
Transmission through time
Future observer
Reconstruction
03 / Distance is time
Our galaxy is about ten billion years old; technological civilisations, on our one example, have existed for hundreds to thousands of years. If such windows are brief, two are unlikely to overlap — and SETI is searching not for contemporary transmissions but for archaeological artefacts of civilisations that may be extinct. (SETI is Archaeology)
The IEEE paper builds this into the data model: archaeological signals are vectors from positions in the past to their present locations, anchored to a fixed celestial reference frame (J2000), so that time relationships become spatial ones — as in astronomy, where every observed signal left its source in the past. (The paper)
04 / The shared problem
Two fields detecting what neither has defined
Neither SETI nor archaeology has a computable definition of technology, yet both exist to detect it. Each substitutes a list: SETI a list of what our own technology does, projected outward; archaeology a typology of things already agreed to be tools.
Astronomy
Time inherited by propagation
Remote observation. Natural generators.
Archaeology
Time must be constructed
Contact traces. Confirmed technological generators.
SETI
Time inherited by propagation
Remote, no contact possible. Generators unconfirmed.
Earth’s archaeological record is the only labelled calibration set available: the one record of technology with independent ground truth. That is what sets the scientific logic in motion — constraining SETI searches and generating hypotheses.
The definition comes from the forward model in the working paper Technology as Boundary-Extending Motion: technology is structured, controlled motion at a boundary that transforms the agent’s effective environment, with a physical quantity Θ — the change in force, distance and speed a motion pattern produces.
A key restriction follows: only standing configurations — what keeps transforming an environment after the motion stops — can be seen across interstellar distance. Nobody resolves a hand axe in use at four parsecs. SETI is archaeology restricted to that deposited regime, at planetary scale.
05 / Search criteria
Seven criteria from an archaeological definition
These are proposals that follow from the framework, not results tested on survey data.
01
Rank by persistence, not resemblance
Persistence decides what a remote observer can see at all.
02
Look for ratcheting
Natural processes make symmetry; only life makes symmetry that ratchets: irreversible accumulation, recombination and deepening.
03
Require a second observable
An anomaly becomes a hypothesis only when a proposed mechanism predicts something else that can be checked.
04
Build the natural null from slow generators
Geological and chemical processes with long histories.
05
Don’t assume early technology looks industrial
Characterise earlier regimes too.
06
State the blind spot
A null result says nothing about technology that leaves no standing configuration.
07
Validate on known terrestrial cases first
Test a discriminator where the origin is known before using it on the sky.
Survey · TESS Sector 59
Reading starlight the way a site is read
Begun in 2023 as an MSc exercise in SETI as archaeology, and now a small survey: it treats stellar light curves the way a site is treated, recording every feature first and then explaining it away layer by layer.
First sweep: 1,095 stars. No technosignature candidates — not surprising in a sample this size. The method checks out against known objects: confirmed planets came out as periodic.
One unexplained dip was followed to its source: an eclipse in BD+67 274, a binary star that none of the catalogues checked lists as eclipsing. A natural eclipse, apparently unreported — not a technosignature.
06 / Where to look
Targets from archaeological priors
The work starts from the one confirmed site, us, and works outward.
- Solar siblings — stars born in the Sun’s birth cluster, sharing its early material.
- Close-passage stars — stars whose paths brought them near the Sun.
- The Earth transit zone — stars that could have seen our own planet transit.
- A control sample — matched stars with no prior; without it, the priors can’t be shown to matter.
07 / Leaving signals
Are we the transmission?
The forward direction runs into the future too. Rather than assuming signals from others are the only interesting ones, ask what signals we could leave for an unknown future intelligence.
Four billion years of Earth’s history will vanish through the passage of time alone. The question isn’t whether it will be lost; it’s whether anyone will have recorded it first.
A research strand to come: durable information transmission, degradation, redundancy, recoverability, unknown encoding systems, and the physical preservation of signals.
08 / Writing
Writing
SETI is Archaeology: Signal Science Across Spacetime
Dylan Foley – Archaeological SETI (Search for Extra-Terrestrial Intelligence) Philosophy of Archaeology SeriesWords:1823 We Know Exactly One Thing About SETI In the search for…
Are We the Transmission?: The Archaeological Record Future Civilizations Will Discover
Introduction Four billion years of planetary history, the complete evolutionary record of life on Earth, from single-celled organisms to technological civilization. The geological transformations…
Why Archaeologists Couldn’t Respond to SETI in 2014
The Unanswered Question In 2014, NASA published “Archaeology, Anthropology, and Interstellar Communication,” edited by Douglas Vakoch. The initiative called for archaeologists to contribute their…
09 / Connections