Water, Then Life: What the Prevalence of Water Actually Licenses Us to Conclude

Water is routinely treated as rare, and that premise is used to support the pessimistic conclusion that we are alone. This paper prices that inference against the modern measured record. Five icy moons of the outer Solar System carry an estimated 62.3 zettalitres of subsurface ocean, about 46.7 times the volume of Earth's oceans, and about 20 times Earth's oceans even with the most model-dependent entry removed. Water vapour was reported in 14 of 19 exoplanets in one uniform atmospheric study and in all 16 successfully analysed atmospheres in another, and water ice is mapped across star-forming regions. On Earth, life appeared within at most about 0.92 billion years of persistent oceans. The paper states exactly what this licenses - water is not a barrier, and the water-to-life step was fast on Earth within stated error bars - and what it does not: one data point cannot set a probability, and no life is claimed on any other world. The counter-case - sealed oceans, missing energy gradients, and absent wet-dry cycling - is presented at full size. Conclusion: the claim that we are alone is not forced by the modern numbers for water.