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Can't we simply extrapolate how many livable planets there are? There are 10^24 planets in the observable universe. Figure out the percentage chance of any one

by chubs 10y ago

Can't we simply extrapolate how many livable planets there are? There are 10^24 planets in the observable universe. Figure out the percentage chance of any one planet being livable and multiply it out. Eg how far you have to be from the sun, correct size for gravity, likelihood of any planet having water, and so on. I read once that it worked out to be 1 in 10^70 planets would be inhabitable after calculating all the known criteria for a livable planet though. If that's accurate, it begs the question, why are we here? A combination of the anthropic principle and multiverses and quantum probabilities? It's easy to go down a rabbithole on this one :)

CharlesW 10y ago
> Can't we simply extrapolate how many livable planets there are? Yes, and beyond that you can ultimately estimate how many civilizations there are Out There that might have the capacity to contact us, commonly referred to as the Drake equation.[1] As Wikipedia notes, YMMV based on assumptions. :^) [1] https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation
- chubs 10y ago
  That's fantastic! Thanks for the link. Learn something new every day.
  - antisthenes 10y ago
    To add to that, along with my comment in the thread: https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter
antisthenes 10y ago
One of the biggest unknowns is the time variable. Recall that it took approximately 3 billion years to go from single-cellular life to multi-cellular life, and another 600 million to get to our level of intelligence. We have no idea how long our civilization will last on a geologic time scale and no idea how long it could take another form of life to evolve in the same manner. Perhaps there was a planet where life existed, but intelligence did not evolve quickly enough before the fusion death of the star. Say it took 6-7 billion to go from single-cellular life to multi-cellular life. By then, the planet might have heated up just enough to become uninhabitable, or the star may have gone out entirely. A star only 30% more massive than the Sun will have ~50% of its longevity, so a 5 billion timeframe might be insufficient to develop life.

by chubs 10y ago

CharlesW 10y ago

> Can't we simply extrapolate how many livable planets there are? Yes, and beyond that you can ultimately estimate how many civilizations there are Out There that might have the capacity to contact us, commonly referred to as the Drake equation.[1] As Wikipedia notes, YMMV based on assumptions. :^) [1] https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation

chubs 10y ago
That's fantastic! Thanks for the link. Learn something new every day.
- antisthenes 10y ago
  To add to that, along with my comment in the thread: https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter

antisthenes 10y ago

One of the biggest unknowns is the time variable. Recall that it took approximately 3 billion years to go from single-cellular life to multi-cellular life, and another 600 million to get to our level of intelligence. We have no idea how long our civilization will last on a geologic time scale and no idea how long it could take another form of life to evolve in the same manner. Perhaps there was a planet where life existed, but intelligence did not evolve quickly enough before the fusion death of the star. Say it took 6-7 billion to go from single-cellular life to multi-cellular life. By then, the planet might have heated up just enough to become uninhabitable, or the star may have gone out entirely. A star only 30% more massive than the Sun will have ~50% of its longevity, so a 5 billion timeframe might be insufficient to develop life.