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> Life exists here on Earth, and our standard best theories say that this was not a miracle, nor was Earth the only place such things could happen. Furthermore,

> Life exists here on Earth, and our standard best theories say that this was not a miracle, nor was Earth the only place such things could happen. Furthermore, our universe also seems very large (perhaps infinite). Thus our standard best theories predict that advanced life has appeared and will appear many times out there. I'm no expert on abiogenesis, but my understanding was that we're nowhere near being able to estimate its probability like this. Sure it could be that life commonly emerges from Earth-like conditions when given enough time, but it could also be that life requires such an extraordinarily unlikely sequence of events (to get started and then thrive) that it only occurs on one planet in every googolplex universes. > [10% chance that] A sibling star gave rise to a long-lived advanced civ long before now I'd like to see the reasoning behind this estimate (or any of the other numbers given).

koheripbal 5y ago
While we do not know the probability of abiogenesis, we can make an educated guess as to the range of probable likelihoods. ie, the probability of the probability. I read a paper on this a while ago, which I cannot find now, but it places the likelihood at some meaningful percentage per million years, which in aggregate across several orders of magnitude of planets, makes life elsewhere in the universe very likely. It uses the statistical notion that Earth should not be modeled as a single data point, but as a series that you integrate over, and concludes that since life emerged so soon after Earth became habitable, that the emergence of life is likely likely (the probability of the probability) - within the lifespan of a similar star. To give you a more clear example... Imagine a handing a subject a bag containing a die with an unknown number of sides. You ask a subject to reach into the bag, pull out a die and keep rolling it until he gets a 1. ...and then report to you only the number of times it took to roll a one. In statistics, can you infer a probability on the number of sides of that die, based upon how long it took the subject to reach a 1 - even if the experiment is only performed once? The answer is YES. If the subject only had to roll the die twice to get a 1, you can estimate that the die probably had very few sides. Similarly, if the subject that it took a million tries to roll a 1, you can very comfortably say that the die was not 2 sided (a coin). In the same vein, since life appeared on Earth in the few hundred(s) of millions of years after it became habitable, then the likelihood is probably not close enough to zero to rule out life in the cosmos. Treating Earth as one data point is an unwise oversimplification.
- user-the-name 5y ago
  > While we do not know the probability of abiogenesis, we can make an educated guess as to the range of probable likelihoods. ie, the probability of the probability. No, we can't. > Treating Earth as one data point is an unwise oversimplification. It is one data point. We have no other. We can't know anything about any others. Doing anything else is wishful thinking hidden in fancy methodology, just like this article. It is all nonsense. We really, really do not know a single thing about the likeliness of life appearing. Not until we find a second data point.
  - koheripbal 5y ago
    You did not address anything in my comment. You just handwaved it as "nonsense". If you don't have anything meaningful to contribute, it's better to just not comment at all.
    - user-the-name 5y ago
      There's nothing there that can be addressed. None of it makes sense.

koheripbal 5y ago

While we do not know the probability of abiogenesis, we can make an educated guess as to the range of probable likelihoods. ie, the probability of the probability. I read a paper on this a while ago, which I cannot find now, but it places the likelihood at some meaningful percentage per million years, which in aggregate across several orders of magnitude of planets, makes life elsewhere in the universe very likely. It uses the statistical notion that Earth should not be modeled as a single data point, but as a series that you integrate over, and concludes that since life emerged so soon after Earth became habitable, that the emergence of life is likely likely (the probability of the probability) - within the lifespan of a similar star. To give you a more clear example... Imagine a handing a subject a bag containing a die with an unknown number of sides. You ask a subject to reach into the bag, pull out a die and keep rolling it until he gets a 1. ...and then report to you only the number of times it took to roll a one. In statistics, can you infer a probability on the number of sides of that die, based upon how long it took the subject to reach a 1 - even if the experiment is only performed once? The answer is YES. If the subject only had to roll the die twice to get a 1, you can estimate that the die probably had very few sides. Similarly, if the subject that it took a million tries to roll a 1, you can very comfortably say that the die was not 2 sided (a coin). In the same vein, since life appeared on Earth in the few hundred(s) of millions of years after it became habitable, then the likelihood is probably not close enough to zero to rule out life in the cosmos. Treating Earth as one data point is an unwise oversimplification.

user-the-name 5y ago
> While we do not know the probability of abiogenesis, we can make an educated guess as to the range of probable likelihoods. ie, the probability of the probability. No, we can't. > Treating Earth as one data point is an unwise oversimplification. It is one data point. We have no other. We can't know anything about any others. Doing anything else is wishful thinking hidden in fancy methodology, just like this article. It is all nonsense. We really, really do not know a single thing about the likeliness of life appearing. Not until we find a second data point.
- koheripbal 5y ago
  You did not address anything in my comment. You just handwaved it as "nonsense". If you don't have anything meaningful to contribute, it's better to just not comment at all.
  - user-the-name 5y ago
    There's nothing there that can be addressed. None of it makes sense.