How are we able to tell what is at the earth's core?

In short, I don't know - it's beyond my expertise. I'm not sure we have any way to measure boron; it's not (afaik) commonly detected in stellar atmospheres. I haven't checked the molecule lists (https://www.reddit.com/r/askscience/comments/124xb33/is_nacl_relatively_common_in_the_galaxyuniverse/je2x7n8/), but I'm not aware of any boron-containing molecules either. Your arguments sound plausible, but I'm afraid I can't weigh in on the argument.

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We have tons of PrP^wt of which it is very rare for one to become PrP^sc . If PrP^sc forms it's estimated to take around a decade to kill, at least in humans.

As far as we can tell, you can't fix a misshapen PrP (aka prion). Those "prions" in the paper you are referencing are yeast proteins that have distinct conformations that can propagate like human prions. All humans have tons of PrP but it's rare for one to become a prion. However, once one does it can start a chain reaction.

u/adamginburg

I recognize that this is not NA+ and Cl- related, but it does have to do with the relative abundance of low atomic number elements, so I was wondering if you would be willing to weigh in on it.

I friend of mine and I are trying to guess what the long-term potential for various forms of space settlement and colonization are across all conceivable intelligent species... a sort of: These are the universal ground rules kind of list. For that reason, we've been focusing on energy sources on the thinking that regardless of the exact nature or needs of the intelligent species, they will need energy sources to engage in whatever their civilization does.

To that end, we have a disagreement on the viability of proton-boron fusion as a sustainable form of energy with particular emphasis on small icy bodies on the outskirts of solar systems (Kuiper belt and Oort cloud bodies). The disagreement is concerning the relative abundance of Boron. As you know, Boron is, like Beryllium, mostly NOT formed in stars or left over from the big bang, but rather formed from Lithium and cosmic rays. I've been arguing that because stellar magnetic fields partially protect objects inside them from cosmic rays, we should, if anything, see MORE Boron in small icy bodies that spend all or most of their time outside stellar magnetic fields, and that therefore there should be more than enough boron to sustain a proton-boron-fusion based civilization in the outskirts of a solar system without ever needing to actually approach a star.

Am I right? Do we have any way of knowing how much boron is in such small icy bodies?

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They are still the same species, the reason why they are so different from one other (compared to humans for example, who also have different skin colors, hair colors, faces types etc) is that we artificially bred them into those multiple races.

If we were to do the same for humans and specifically breed only redhair people with long limbs, only tall thin black skin people, etc., we could also get to more extreme physical differences between human populations.

Why is iron more common than lighter elements?

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typically in nature a population explosion event occurs when top-down forces, predation, go away for some reason, like parvovirus in wolves (or extirpation by humans) can result in moose, deer, or caribou population explosion. Invariably, bottom-up forces will then kick in like sickness and starvation. The whole ecosystem takes a big hit in indirect ways. Humans have staved this off to some degree by our technological abilities to feed and heal ourselves. At the expense of many other species of course. But make no mistake. Things are getting worse. We can run, but we can't hide from it. Cheers.

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Ah right! I think I mushed two youtube videos from one channel together in my memory. The second part of my question was really what I was interested in, though. Given some distribution of the elements across the universe, can we estimate the prevalence of the compounds they form, based on the elements' reactivities? For instance, this would predict that hydrocarbons should be common, since hydrogen is extremely prevalent and carbon is extremely chemically reactive?

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I'm not sure salt absorption lines have ever been detected. We detected emission lines from gas-phase salt.

NaCl, as a single pairing of one Na atom and one Cl atom, is a molecule. But I think you're right, we consider crystalline ionic compounds to be ionic compounds, not molecules, when they're solids. Probably there are some isolated NaCl molecules on Earth, but you're right that when we encounter salt, it's mostly in crystals.

However, in gas phase, it floats around as NaCl. If you heated NaCl hot enough in a lab at atmospheric pressure (~1500 K according to another poster), you would have a bunch of NaCl gas floating around.

YES!

Professor Stanton was the woman I was thinking of! Thanks for posting!

Zipf's law is a continuous power law distribution; while it's a good approximation when we don't know much, and therefore describes a ton of nature to the accuracy that we can measure it, it's not the best we can do with elemental abundances. Elements do something funnier; see the figures on https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements

Yeah, as others have said, there are other salts. We detected a couple of the most common and familiar ones: NaCl and KCl.

Well, it's a bit worse than that. We don't really know what to expect. We can estimate how much NaCl there is based on how much Na and how much Cl there is - we can measure those directly from stars, or specifically the sun (https://ui.adsabs.harvard.edu/abs/2009ARA%26A..47..481A/abstract) - but then we have to guess at how much of each of those atoms is in NaCl. Some Na is in other molecules (e.g., NaOH), and some Cl is in other molecules (like HCl). It might even be integrated into more complex molecules or integrated into crystalline structures (I don't know much about solid state materials; this is someone else's domain).

But, generally, you're right: we have no direct evidence as to where NaCl is, so I wouldn't claim to know. It is possible that there's a ton of NaCl sitting on dust grains, undetectable, but it is also possible that there's virtually no NaCl in dust, and it only exists where we see it. Our best bet, based on what we know of chemistry from lab work, is that Na and Cl are in NaCl on dust grains, but we have never measured that, as far as I'm aware. It's possible there are measurements from, say, the stardust mission, but I haven't seen those results.

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It has to stay stuck together as a molecule, as NaCl bonded together, to be NaCl gas, otherwise it's a mix of atomic Na+ gas and atomic Cl-. That's probably how it comes out of the dying AGB stars. Gas doesn't have structure, though. It just fills whatever vessel it's in. If that's the ISM, it just spreads out until it's pressed on by something else.