No direct observational evidence of extraterrestrial life yet exists. The surrounding work establishes that habitable environments are common, but the question itself remains unscored: evidence mass is far below the threshold for any consensus.
Microbial or more complex life exists somewhere beyond Earth.
The relevant literature is a framework, not a result. The Drake equation organises the unknowns rather than resolving them Drake 1965. Exoplanet surveys show that planets — including potentially habitable ones — are common Borucki 2011, and reviews catalogue candidate biosignatures, but none are confirmed Cabrol 2016.
The single contested positive claim concerns purported microfossils in a Martian meteorite McKay 1996, which remains disputed. With almost all evidence neutral and total mass low, the score sits near 50 — the manuscript's signal for "not yet answerable", distinct from a balanced stalemate.
The score is computed deterministically from the citations below, following the methodology in the manuscript (§5). Nothing is hand-tuned per entry — change the evidence and the number moves.
| Citation | sᵢ | mᵢ | tᵢ | e^(−tᵢ/T) | mᵢ·e^(−tᵢ/T) | sᵢ·mᵢ·e^(−tᵢ/T) |
|---|---|---|---|---|---|---|
| Drake 1965 | 0 | 2.0 | 61y | 0.466 | 0.93 | +0.00 |
| Borucki 2011 | 0 | 2.5 | 15y | 0.829 | 2.07 | +0.00 |
| Cabrol 2016 | 0 | 2.0 | 10y | 0.882 | 1.76 | +0.00 |
| McKay 1996 | +1 | 1.5 | 30y | 0.687 | 1.03 | +1.03 |
| Σ over citations | 8.0 | 5.80 Mₚ | +1.03 Xₚ·Mₚ |
Reading it: the verdict is Insufficient evidence. Direction comes only from Xₚ (tanh is always positive); certainty comes from tanh(Mₚ/W₀) = 0.19. Because Cₚ = 50 when Xₚ = 0 regardless of mass, a balanced stalemate and an unstudied question both read as 50 — which is why Mₚ is always shown alongside the score.
| Revision | Score Cₚ | Mass Mₚ | Center Xₚ |
|---|---|---|---|
| Current revision | 52 | 5.8 | +0.18 |
| 23 May 2026 | 52↑ +1 | 7.8 | +0.13 |
| 11 May 2026 | 51 | 6.9 | +0.10 |