cloaked in the pall of the ace of spaces
With tens or even hundreds of billions of potentially habitable planets within our galaxy, the question becomes: are we alone?
Many scientists and commentators equate “more planets” with “more E.T.s”. However, the violence and instability of the early formation and evolution of rocky planets suggests that most aliens will be extinct fossil microbes.
Just as dead dinosaurs don’t walk, talk or breathe, microbes that have been fossilised for billions of years are not easy to detect by the remote sampling of exoplanetary atmospheres.
In research published [PDF] in the journal Astrobiology, we argue that early extinction could be the cosmic default for life in the universe. This is because the earliest habitable conditions may be unstable. […] Inhabited planets may be rare in the universe, not because emergent life is rare, but because habitable environments are difficult to maintain during the first billion years.
Our suggestion that the universe is filled with dead aliens might disappoint some, but the universe is under no obligation to prevent disappointment.
previously { Where is the Great Filter? Behind us, or not behind us? If the filter is in our past, there must be some extremely improbable step in the sequence of events whereby an Earth-like planet gives rise to an intelligent species comparable in its technological sophistication to our contemporary human civilization. }
still { The Day the Earth Stood Still, 1951 }
