Comment on Sea Level
exasperation@lemmy.dbzer0.com 1 week agoThe 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 1 week 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 1 week ago
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.
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 1 week ago
I can, precisely because you are forcing this discussion to be about probability
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?
exasperation@lemmy.dbzer0.com 1 week ago
I’m pointing out the fallacious reasoning behind your view that with enough chances, it is inevitable that every possible outcome occurs at least once. That does not necessarily follow, simply because it is possible to generate events of infinitesimal probability, simply because n! grows much faster than x^n. That’s just plain math.
Turning to whether the rare earth hypothesis itself is correct or not, I don’t actually have a strong view on this. I just know that you can’t reason your way into disproving the rare earth hypothesis simply by saying “the earth is possible and therefore common, because everything that is possible is inevitably common.”
I don’t see how else this could be anything but probabilistic. Unless you’re saying every star is the same size as the sun and every star has an earth-like planet orbiting it in he habitable zone, the probability of those things is obviously less than 100%. We can already observe counterexamples that proves those aren’t 100%.
So if you want to argue that there’s no way the probability is less than 1 in 10^21, fine. Then we’re having the conversation about the actual probabilities. But my whole point, since my first comment in this thread, is that it is not enough to say “I think there are 10^21 planets so life is inevitable.” That’s not sufficient to support that conclusion.
Debate whether a large moon, plate tectonics, a magnetic field, an atmosphere, an ozone layer, a Jupiter-like neighbor, a G-type star, and what ratios of specific elements need to be present on a planet to qualify. I’ll leave the actual estimates of those probabilities to others. But each of these factors has a non-100% chance of happening on any given planet, and it becomes a question of whether the probabilities stack in a way that overcomes the sheer number of stars and planets there are. And that’s the thing I’m sure about, that you simply can’t ignore the factorial expansion of those factors because you think that there are enough planets in the universe to make that irrelevant.