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It is probable that Mars had life even before Earth. It had water oceans for hundreds of millions of years, which is approximately how long it took life to emer

by bmitc 3y ago

It is probable that Mars had life even before Earth. It had water oceans for hundreds of millions of years, which is approximately how long it took life to emerge on Earth. Venus potentially had life as well, in addition to some of the moons. Let's be conservative and say that 2 of the n bodies in the solar system had life and one had so-called intelligent life emerge. It seems pretty damn likely given the sheer numbers of the Universe that intelligent life also emerged elsewhere. We currently can barely detect exoplanets. It isn't a surprise that we haven't detected intelligent life. How can you find something you can't see? From what we know, life is effectively guaranteed to emerge on a planet with a rocky core and water in the habitable zone. Are there planets like this? Yes, lots, probably.

DennisP 3y ago
We can't know that life is guaranteed unless we find another example of life arising independently. We don't know how many random chemical reactions are required for life to be likely. We probably agree that a small puddle isn't likely to spontaneously generate life within a century. We like to think that one planet for a billion years is about the right size. But it could be that it takes a whole universe of planets before it's likely to happen once. If that were the case, then the universe would look exactly like it does now, with us living on the planet where it happened and no life discovered elsewhere so far.
- bmitc 3y ago
  > We can't know that life is guaranteed unless we find another example of life arising independently. Of course not. But that's why we discuss probabilities. We also can't discuss definitively about things that we have no reasonable ways to detect. So claims about there's no life because we would have seen them is completely worthless given that we have very, very few, if any, ways to detect such life. Assuming it existed, are we even able to detect a planet like Earth with similar animal and human activity in any other solar system, even in the Milky Way? I am personally not aware of such general capability.
  - DennisP 3y ago
    Yes, but we have no idea what the probabilities are. We have no basis for saying "it is probable that Mars had life." If we found native life on Europa or something, that would change things completely. Independent life arising at least twice in the same solar system would make it clear that life is common. But a sample size of one, with the anthropic principle, leaves us no clue. Life might be common, or we might be unique.
AnimalMuppet 3y ago
Your post goes off the rails on the third word ("probable"). That's not probable, without a whole lot of assumptions, even assuming that Mars did in fact have water for hundreds of millions of years. You're assuming something. Maybe something like "a world with water has high probability of life emerging". That is a massive assumption. Given that I find that assumption implausible, I consider the rest of the post to be built on a flawed foundation.
- bmitc 3y ago
  > You're assuming something. Maybe something like "a world with water has high probability of life emerging". That is a massive assumption. With what else I added: a rocky planet with water, an active molten metal core, and in the habitable zone. It is indeed my understanding that life on such a planet is quite probable. Life is described as "not hard" given such conditions. And Mars was such a planet. It is also my understanding that Mars absolutely had large bodies of water. Basins, waterfalls, etc. have been discovered that could have only been formed via large, flowing bodies of water. And this would have been during a time where Mars' core was still active and the Sun was hotter, making Mars warmer than it is now.
  - AnimalMuppet 3y ago
    > It is indeed my understanding that life on such a planet is quite probable. Life is described as "not hard" given such conditions. Yeah, see, that's an assumption. And "not hard" is very far from a universally-accepted evaluation of the odds for that situation. So, when someone like me comes along who doesn't buy the assumption, can you provide a foundation for it that is stronger than "yes, I assume it" or "everyone knows"?
    - bmitc 3y ago
      I know what an assumption is. > can you provide a foundation for it that is stronger than "yes, I assume it" or "everyone knows"? That's not really an accurate portrayal of my argument. But here's sources I know of. * Origins of Life course on Complexity Explorer * The Origin and Nature of Life on Earth: The Emergence of the Fourth Geosphere * Every Life Is on Fire: How Thermodynamics Explains the Origins of Living Things

by bmitc 3y ago

DennisP 3y ago

We can't know that life is guaranteed unless we find another example of life arising independently. We don't know how many random chemical reactions are required for life to be likely. We probably agree that a small puddle isn't likely to spontaneously generate life within a century. We like to think that one planet for a billion years is about the right size. But it could be that it takes a whole universe of planets before it's likely to happen once. If that were the case, then the universe would look exactly like it does now, with us living on the planet where it happened and no life discovered elsewhere so far.

bmitc 3y ago
> We can't know that life is guaranteed unless we find another example of life arising independently. Of course not. But that's why we discuss probabilities. We also can't discuss definitively about things that we have no reasonable ways to detect. So claims about there's no life because we would have seen them is completely worthless given that we have very, very few, if any, ways to detect such life. Assuming it existed, are we even able to detect a planet like Earth with similar animal and human activity in any other solar system, even in the Milky Way? I am personally not aware of such general capability.
- DennisP 3y ago
  Yes, but we have no idea what the probabilities are. We have no basis for saying "it is probable that Mars had life." If we found native life on Europa or something, that would change things completely. Independent life arising at least twice in the same solar system would make it clear that life is common. But a sample size of one, with the anthropic principle, leaves us no clue. Life might be common, or we might be unique.

AnimalMuppet 3y ago

Your post goes off the rails on the third word ("probable"). That's not probable, without a whole lot of assumptions, even assuming that Mars did in fact have water for hundreds of millions of years. You're assuming something. Maybe something like "a world with water has high probability of life emerging". That is a massive assumption. Given that I find that assumption implausible, I consider the rest of the post to be built on a flawed foundation.

bmitc 3y ago
> You're assuming something. Maybe something like "a world with water has high probability of life emerging". That is a massive assumption. With what else I added: a rocky planet with water, an active molten metal core, and in the habitable zone. It is indeed my understanding that life on such a planet is quite probable. Life is described as "not hard" given such conditions. And Mars was such a planet. It is also my understanding that Mars absolutely had large bodies of water. Basins, waterfalls, etc. have been discovered that could have only been formed via large, flowing bodies of water. And this would have been during a time where Mars' core was still active and the Sun was hotter, making Mars warmer than it is now.
- AnimalMuppet 3y ago
  > It is indeed my understanding that life on such a planet is quite probable. Life is described as "not hard" given such conditions. Yeah, see, that's an assumption. And "not hard" is very far from a universally-accepted evaluation of the odds for that situation. So, when someone like me comes along who doesn't buy the assumption, can you provide a foundation for it that is stronger than "yes, I assume it" or "everyone knows"?
  - bmitc 3y ago
    I know what an assumption is. > can you provide a foundation for it that is stronger than "yes, I assume it" or "everyone knows"? That's not really an accurate portrayal of my argument. But here's sources I know of. * Origins of Life course on Complexity Explorer * The Origin and Nature of Life on Earth: The Emergence of the Fourth Geosphere * Every Life Is on Fire: How Thermodynamics Explains the Origins of Living Things