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Why do you speak with such confidence when you have no data? If life is common as you've stated, then where is it? Whether ultimately true or untrue, your asser

by vsnf 3y ago

Why do you speak with such confidence when you have no data? If life is common as you've stated, then where is it? Whether ultimately true or untrue, your assertion is without evidence, yet presented as though it is the unassailable truth.

ceejayoz 3y ago
It's generally a fairly safe assumption that if something can happen once, it can likely happen twice. It's not guaranteed, but with fifteen billion years and 200 sextillion stars to work with, even the most unlikely things are pretty likely.
- oneshtein 3y ago
  Space is hostile to life. After 4 billion years, life cannot propagate to nearest planet. We are lucky that life on our planet is not erased yet, but it will be erased in about 2-4 billion years, when oceans will boil, then when core will freeze, then when Sun will consume the planet. Out of 6-8 billion years, 3 billion years was spent in single-cell form of life. We are extremely lucky. We can calculate how many stars are formed after a supernova event, how many Earth-size planets in the habitable zone are survived after collision of two objects of comparable size, how many of them survived with ocean and large moon, to make large tidal waves (I suspect that first cells were formed as greasy puddles, then partially dried out, which created a membrane), then how many of them were far enough from a supernova or not erased by it own star in 4 billion years at least. I suspect, that final number will be much less that 200 sextillion, because, to avoid a supernova, a star must be formed in a less dense region.
  - ceejayoz 3y ago
    > Space is hostile to life. Space is hostile to most Earth-style life... but so are hot springs, undersea vents, and mile-deep mines, all of which we've unexpectedly found life in. Tardigrades can survive a complete vacuum and temperatures from -450 to 300 Fahrenheit, plus significant radiation. Slow-growing life hopping around in the Oort clouds and taking million-year interstellar hibernations on rogue planets might be common, who knows? > in the habitable zone Same mistake here. We define "habitable zone" very, very narrowly based on our own circumstances; it's potentially a massive misnomer.
    - nyokodo 3y ago
      > who knows? Precisely the point, no one knows yet as far as is publicly known. Anyone who purports to know ought to front up with the evidence or admit they don’t know.
- mr_mitm 3y ago
  That's ignoring an anthrophenic argument and the finiteness of the observable universe. The probability for life to evolve on any given planet may be 10^-100. But because we obviously observe the planet where life happened to evolve, we cannot tell whether the probability is 10^-100 or 1/10. That would mean that it would most likely only happen once in the observable universe, and the next instance may be many universe distances away. That would make us alone, even if we assume that the universe is infinite.

by vsnf 3y ago

ceejayoz 3y ago

It's generally a fairly safe assumption that if something can happen once, it can likely happen twice. It's not guaranteed, but with fifteen billion years and 200 sextillion stars to work with, even the most unlikely things are pretty likely.

oneshtein 3y ago
Space is hostile to life. After 4 billion years, life cannot propagate to nearest planet. We are lucky that life on our planet is not erased yet, but it will be erased in about 2-4 billion years, when oceans will boil, then when core will freeze, then when Sun will consume the planet. Out of 6-8 billion years, 3 billion years was spent in single-cell form of life. We are extremely lucky. We can calculate how many stars are formed after a supernova event, how many Earth-size planets in the habitable zone are survived after collision of two objects of comparable size, how many of them survived with ocean and large moon, to make large tidal waves (I suspect that first cells were formed as greasy puddles, then partially dried out, which created a membrane), then how many of them were far enough from a supernova or not erased by it own star in 4 billion years at least. I suspect, that final number will be much less that 200 sextillion, because, to avoid a supernova, a star must be formed in a less dense region.
- ceejayoz 3y ago
  > Space is hostile to life. Space is hostile to most Earth-style life... but so are hot springs, undersea vents, and mile-deep mines, all of which we've unexpectedly found life in. Tardigrades can survive a complete vacuum and temperatures from -450 to 300 Fahrenheit, plus significant radiation. Slow-growing life hopping around in the Oort clouds and taking million-year interstellar hibernations on rogue planets might be common, who knows? > in the habitable zone Same mistake here. We define "habitable zone" very, very narrowly based on our own circumstances; it's potentially a massive misnomer.
  - nyokodo 3y ago
    > who knows? Precisely the point, no one knows yet as far as is publicly known. Anyone who purports to know ought to front up with the evidence or admit they don’t know.
mr_mitm 3y ago
That's ignoring an anthrophenic argument and the finiteness of the observable universe. The probability for life to evolve on any given planet may be 10^-100. But because we obviously observe the planet where life happened to evolve, we cannot tell whether the probability is 10^-100 or 1/10. That would mean that it would most likely only happen once in the observable universe, and the next instance may be many universe distances away. That would make us alone, even if we assume that the universe is infinite.