We measure how belief is made: in a story, in an idea, in a live event.
We examine evidence of life and civilizations beyond Earth.
Time changes traces, while survey sensitivity limits what we can find. Explore how brightness or size changes the model results, alongside the assumptions behind them.
Go to the investigation articlePick a place, then move the slider toward fainter or smaller to see where the survey weakens.
A larger number means a fainter, usually smaller, object.
Survey sensitivity 30.9% · 10.3M years
Survey sensitivity: the share of traces this survey would catch.
Equivalent production interval to reach 95% detection probabilityIf a civilization left one trace here every 10.3M years on average, the model would give a 95% chance that the survey finds at least one, under the conditions below. A perfect survey needs about one every 33.4M years on average; a shorter interval means the survey needs more traces, so it is weaker.
95% is the survey's chance of finding a trace in this assumed case, not the chance that a civilization exists.
This case needs about the same number of traces as the starting point.
Comparison conditions (continuous production): we choose the last 100 million years for traces to build up. This example is deliberately optimistic: colonies remain in almost all suitable systems and leave all their traces in the search region.
We assume the traces remain in the orbits we search, or on the surface studied, and we recognize them if we see them. The survival option sets the assumed decay. If any condition weakens, the inference weakens.
Each environment concerns objects with different properties; this comparison does not say where the same spacecraft would be easiest to find.
Earth's L4 Trojan region is an area on Earth's orbit where an object can travel along with Earth. The comparison assumes the stable Earth-Trojan region used by the WFST survey.
The window displays stored research points without running a new model or calculating new values between points. The survival assumption changes how long surviving traces build up and the required production rate, while survey sensitivity stays the same. We stop showing the numerical production rate and interval when sensitivity falls below 0.01%; this does not mean detection is impossible.
H is absolute magnitude; apparent r-band magnitude describes brightness at the observer. Neither becomes a size in metres without a reflectivity assumption.
Sensitivity can vary slightly between adjacent survey-grid points. The starting point is not necessarily the best point; not every step toward fainter objects reduces sensitivity.
Why haven't we found a trace of alien civilizations? We examine Fermi's argument and calculate what non-detection on the Moon, near-Earth asteroids, Trojan orbits and the outer Solar System allows us to conclude, and under which conditions.
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