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Life started on Earth relatively early in it's history, so a high percentage isn't unreasonable to assume. It took 4 billion years after that and several mass
by CoolGuySteve 9y ago
Life started on Earth relatively early in it's history, so a high percentage isn't unreasonable to assume.
It took 4 billion years after that and several mass extinction events for a species to evolve that can send radio signals (and so far only briefly ), so even on an astronomical scale we might be rare.
- le-mark 9y agoAgreed, also consider the importance of a large moon in our system, which cause massive tidal flooding, and churning geology for all these years. How important was periodic deposit of water based life on dry land for the eventual evolution of a technological civilization? One might suppose very important. Thus one could posit that technological civilizations, requiring both a planet in the habitable zone of a star and also an appropriately large satellite companion, could be even less probable. It would be interesting to know how probable similar earth/moon systems are in the universe.