4 ms·

I guess the argument is something like 'if life is unlikely to evolve, then it is surprising to find ourselves existing so early in the history of the universe.

• pfdietz 3y ago
  But we are not "so early" in the history of the universe. Something like 95% of all the stars that will ever be formed have already been formed. It's actually rather late in the day.
  • nyssos 3y ago
    > Something like 95% of all the stars that will ever be formed have already been formed. Sure, but clearly civilizations don't exclusively develop around newly formed stars: we didn't. Most stars are red dwarves and will continue shining for trillions of years.
    • pfdietz 3y ago
      That's true, but the star formation rate peaked around Z = 1.5, which was long before the solar system formed. By the time our solar system formed the rate was maybe 1/4 of the peak, and has fallen since. https://arxiv.org/pdf/2009.11126.pdf https://arxiv.org/pdf/2009.11126.pdf I don't think it's a reasonable assumption that the rate of life (or civilization) formation would remain constant on a planet around a red dwarf over extended periods of time. I don't think Earth could survive for trillions of years as a life bearing planet, even with a more long lived star. Without radioactivity and primordial heat, plate tectonics would cease and the magnetic field would go away. The lack of magnetic field would mean the atmosphere would be lost as well.
  • qnleigh 3y ago
    I agree. I didn't know that statistic, but that was my impression from other things I've heard.