They might not exist

The widespread notion that life probably exists on many or all of the other habitable planets in the universe is largely based on the observation that it arose relatively quickly here on Earth — within a few hundred million years of the planet’s formation. But in truth, we know next to nothing about the likelihood of that momentous event. Despite decades of Frankenstein-like effort, we haven’t even come close to triggering the genesis of life in the lab.

“Abiogenesis,” or life arising from lifeless chemicals, could be exceedingly rare. Life on Earth could be an anomaly.

If you think it improbable that life would only happen once — and that that life would happen be us — that’s now known to be a misconception. A pair of Princeton astrophysicists recently applied a new kind of statistical analysis to the early timing of the genesis of life on Earth, and determined that Earth’s history says absolutely nothing about the probability of life arising elsewhere. Aliens could be everywhere; they could be nowhere.

Ragnar Larsen