Alt text: They’re up there with coral islands, lightning, and caterpillars turning into butterflies.

  • exasperation@lemmy.dbzer0.com
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    1 month ago

    If we live on a habitable planet then it’s logical to make the assumption that habitable planets are common.

    That’s what I take issue with. I don’t think that follows.

    If I have a random deck of cards, I can’t assume that the deck order is common. Or, if I flip a coin 20 times I can’t assume that the specific heads/tails order that results is commonly encountered, either. Just because it actually happened doesn’t mean that the a priori probability of it happening was likely.

    The Copernican Principle is assuming that all decks of cards or all flipped coins follow the same rules. I’m not disagreeing with that premise, but I’m showing that no matter how many decks or coins you use, the probability of any specific result may be infinitesimal even with as many decks as there are planets in the universe.

    Showing me good reason to believe that earth sized planets have a 20% chance of showing up in habitable zones still doesn’t answer the other questions I have about plate tectonics, elemental composition, magnetic fields, large moons, etc. Stacking dozens of variables with conditional probabilities can still produce numbers so small that even every star in the universe representing a “try” might not lead to a high probability result.

    • crapwittyname@feddit.uk
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      1 month ago

      I think you need to let the deck of cards metaphor go! A deck of cards is specifically designed by intelligent minds to generate random outcomes, whereby natural processes follow predictable paths, and the outcomes are limited by natural laws. There is no intelligent mind altering the outcomes, or designing for or against randomness.

      It’s a fair assumption to say we are not privileged observers if the universe because there is zero evidence to the contrary.

      There are answers to all of your questions about elemental makeup of planets, magnetosphere, moon and tectonic plate formation, but it’s a lot of reading to get them.

      • exasperation@lemmy.dbzer0.com
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        30 days ago

        The math I’m talking about still works with weighted probabilities or conditional probabilities. The underlying factorial math expands the number of possibilities way faster than the number of “tries” can increase the likelihood of at least one hit.

        The point is: the fact that something has already happened is not proof that it is a high probability event. The deck of cards hypothetical is merely an example of that phenomenon. Applying different weights (e.g., ignoring the suits of cards) doesn’t change that basic mathematical phenomenon, both only re-weights the probabilities to be bigger. But lining up a bunch of probabilities in a row still multiplies them in a way that results in a infinitesimal probability.

        If there are only billions of earth-like planets in our galaxy, and only trillions of galaxies, that’s still only 10^21 chances at life. Yes, that’s an unfathomably large number for the human brain to process, but it’s also nowhere near the numbers that can be generated through factorial expansion, so if the probability of life arising is something like 10^30 on any of those planets, the expected number of life bearing planets would be pretty much zero.

        • crapwittyname@feddit.uk
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          30 days ago

          It’s not probabilities that dictate these processes though, as stated above. It’s natural laws. Certainties. Like the increase of entropy, or the conservation laws. So a planet isn’t just 50% likely to form with rocky bias withín the frost line, it is certain to do so. I’m sorry but probability rarely tells even a small part of the story of natural processes.
          The fact that something has happened nearly every time we see a chance of it happening very much does make it a high probability event, cf. Bayesian inference.

          • exasperation@lemmy.dbzer0.com
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            30 days ago

            So a planet isn’t just 50% likely to form with rocky bias withín the frost line, it is certain to do so.

            No, you’re skipping a step. For any n number of chances, the likelihood of something with probability p happening at least once is 1 - (1 - p)^n . You may think that with high enough n that it doesn’t matter what p is, because the exponential increase from n overwhelms the math to where the whole term basically converges onto 1, but my point is that there are combinatorics where the exponential increase in n is still dwarfed by the effect of the factorial increase in 1/p.

            The probability of a rocky planet to form within a habitable zone is about 20% for any given star, according to your earlier link. How many will have a moon like ours? How many other life-sustaining characteristics will it have? If your argument is that the probability is 100% for every star, well, that’s just wrong. If your argument is that it is inevitable in that the probability approaches 100% if you look at enough stars, then you’re ignoring the entire point I’ve been making here, that you would have to show that the probability p is large enough that one would expect the overall probability to be found in at least some of the n stars viewed.

            The fact that something has happened nearly every time we see a chance of it happening very much does make it a high probability event, cf. Bayesian inference.

            No, my deck of cards counterexample directly disproves this conjecture of yours. And you can’t talk about Bayes theorem while simultaneously saying that this isn’t a discussion about probability.

            And you also can’t talk about natural laws without probability, either, as quantum mechanics itself is probability distributions.

            So I’ll continue to point out that the vastness of space might mean that the n is in the order of 10^21, but I can simultaneously recognize that 10^21 is a mind bogglingly large number while still not being large enough.

            • crapwittyname@feddit.uk
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              28 days ago

              And you can’t talk about Bayes theorem while simultaneously saying that this isn’t a discussion about probability.

              I can, because you are forcing this discussion to be about probability

              And you also can’t talk about natural laws without probability, either, as quantum mechanics itself is probability distributions.

              Literally none of the effects you have chosen to discuss are quantum effects.

              Look I’m sorry, but I don’t think the evidence points to p<10E-21 or anywhere near it. Why would the only solar system we’re able to study be so unique? It’s magical thinking. Apart from the moon and plate tectonics being nice, but not essential to complex life, which other factors are you proposing conspire to lower the probability of life to this practical impossibility?