Where is everybody? The Fermi paradox and the search for technosignatures
The galaxy is old enough and large enough that even slow interstellar colonization should have filled it — yet the sky is silent. The paradox can dissolve through a great filter ahead or behind us, through rarity of intelligence, through our looking wrong, or through civilization lifetimes being short.
Why it is hard
The 'parameter space' of possible technosignatures (wavelength, power, timing, location, persistence) is enormous and largely unexplored. Every candidate signal so far — from Wow! to BLC1 — has yielded to mundane explanation; absence of evidence is not evidence of absence.
Current evidence
Decades of radio SETI (Breakthrough Listen, SETI Institute) have covered ~10^4 stars; JWST-era biosignature work sharpens what 'life' looks like remotely; all detections remain unconfirmed. Statistical 'Drake equation' terms still span orders of magnitude of uncertainty.
Possible approaches
Commensal SETI on all-sky surveys, infrared searches for waste heat (Dyson structures), atmospheric technosignatures (industrial gases) on exoplanets, and anomaly mining of petabyte-scale survey archives for artificial patterns.
Related topics
Sources
- Astrobiology Research — NASA Astrobiology
- What Is a Biosignature? — NASA Science
- The Nexus for Exoplanet System Science — NASA Astrobiology
- NASA Exoplanet Archive — NASA Exoplanet Science Institute / Caltech IPAC