Comment on Sea Level
exasperation@lemmy.dbzer0.com 1 week agoWe know little about solar system formation, but sufficient to say it’s not a card deck shuffle,
Well it’s different in several factors competing in different directions, and it’s not clear to me what the overall aggregate direction is.
The fundamental force of gravity is going to drive a lot of disparate starting points to collapse into similar results.
But in the end, we’re still talking about the probabilistic chances that certain lumpiness in the distribution of mass from supernovas or whatever forms the matter of solar systems, and how each solar system’s spinning disk coalesces into planets with their own elemental composition and orbits and rotations and moons and internal rotation and energy that might make for magnetic fields, plate tectonics, etc.
If the probabilities of those may still have some independence from one another, then even if there are lots of stars like ours and maybe even lots of planets that are earth sized, and lots of planets with the oxygen to make water or carbon to make organic chemistry or the iron to make a magnetic field, we might still recognize that the correlations between these not-fully-independent variables still require stacking probabilities on probabilities at a factorial rate.
While the number of opportunities for those conditions to hit might go up at an exponential rate, if the probabilities are small enough and there are enough necessary factors for life stacking on each other, it’s entirely possible that the exponential expansion of more solar systems than we could fathom is still too small to make for an appreciable probability of the conditions of life.
I don’t know what the probabilities actually are. But I can see how the math of the combinatorics can totally dwarf the math of the vastness of the universe, such that the overall probability remains infinitesimal.
crapwittyname@feddit.uk 1 week ago
The aggregate direction is always towards highest entropy, which means lowest energy state, stability etc. Planets tend to self organise into harmonic orbits with simple whole number ratios, because that’s the lowest energy state. But the result is that we have a nice, stable solar system where planets have relatively circular orbits with nice spacing. Despite the initial chaos of the formation, it’s very likely that all solar systems collapse into this kind of high entropy, regular stability, and what little observations we can make of other systems have confirmed it.
The point is that it’s not at all random, there are irresistible forces at play which narrow the space of what’s possible into a very small box, cosmologically speaking. Matter organises itself into spheres, then into orbits etc. We don’t see disc shaped planets for example because they’re physically impossible to make using natural processes. And we don’t see planetary collisions because they can only happen at the start, in the chaos of system formation. Then it all settles down into a stable, predictable, harmonically resonating system, as the laws of thermodynamics predict.
exasperation@lemmy.dbzer0.com 1 week ago
I’m not disagreeing with you on any of the physics of solar system formation, just disagreeing with your interpretation it means that habitable planets are high probability.
When clouds of dust and gas settle into spherical planets, what makes them rocky? What makes them have magnetic fields, atmospheres, water? What makes it so that the planet in the habitable zone hits those conditions.
The tendency of certain things to develop isn’t a lockstep correlation of 1 between these factors.
We can believe that stars are common. And so are planets. But what combination of factors is required for life, and does that combination start leveraging the math of combinatorics in a way that even billions of planets in each of trillions of galaxies wouldn’t be enough to make it likely that there are other planets that can give rise to life as we know it.
My point isn’t actually about cosmological physics. It’s a point I’m making about the math about probabilities being counterintuitive, in a way that “the vastness of the universe” doesn’t actually mean that life is inevitable. It might still be, but it doesn’t necessarily follow.
crapwittyname@feddit.uk 1 week ago
Well I didn’t specifically say habitable planets are high probability. But it just so happens that they are. Firstly consider the Copernican Principle. If we live on a habitable planet then it’s logical to make the assumption that habitable planets are common. There are strong counterpoints to this, but it’s all very hypothetical anyway so it’s better to just point to the empirical evidence: astronomers estimate that [one in five stars has an earth sized planet in the Goldilocks zone](One in Five Stars Has Earth-sized Planet in Habitable Zone – W. M. Keck Observatory share.google/J40L3PlVnAvee7C7B). In terms of the why, it’s a much more difficult question to answer, but the stages of planetary formation that are proposed include processes whereby heavier elements coagulate together, earlier, and those that end up massive enough then attract lighter elements and become gas giants. Rocky planets formed close to the sun because it was hotter there and water/ice couldn’t form and contaminate the denser elements, although it doesn’t seem to happen that way in other artist systems.
Everywhere we look we see rocky planets and we see water. It’s not unlikely that rocky planets therefore would have liquid water fairly often
exasperation@lemmy.dbzer0.com 1 week ago
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.