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JoshuaZ comments on Open Thread, September 1-15, 2012 - Less Wrong
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It has become increasingly clear over the last year or so that planets can in fact form around highly metal poor stars. Example planet. This both increases the total number of planets to expect and increase the chance that planets formed around the very oldest stars. (Younger stars have higher metal content). One argument against Great Filter concerns is that it might be that life cannot arise much younger than it did on Earth because stars much older than our sun would not have high metal content. This seems to seriously undermine this argument.
How much should this do to our estimates for whether to expect heavy Filtration in front of us? My immediate reaction is that it does make future filtration more likely but not by much since even if planets could form, a lack of carbon and other heavier elements would still make formation of life and its evolution into complicated creatures difficult. Is this analysis accurate?
Are there any metals necessary for life?
Astronomers use metal to mean elements other than hydrogen and helium. Metals in the chemists sense of the word aren't in general necessary. A lot of life is pure CHONPS. However, most complex life involves some amount of metals in the chemical sense (most animals require both iron and selenium for example). And planets which are of low metalicity in the astronomical sense will be necessarily be of extremely low metal content in the chemical sense, since in order to get the actual metals other than just lithium and beryllium require extensive synthesis chains before one gets to them.
Thanks for the clarification!
Wow, Astronomers are lazy. It's not hard to make up new terms for things when the existing ones clearly don't fit. Heck, if making up a word was too difficult they could have used an arbitrary acronym.
Well, when most of what they have to work with is hydrogen, a whiff of helium, and a tiny smattering of literally everything else ever, it's kinda hard to blame 'em. ;p
Not really. If you look at a periodic table, the vast majority actually are metals.
The vast majority are metals, and saying they all are is wrong (except in as much as authority within the clique is able to redefine such things). It's also distasteful and lazy to formalise the misuse. I'd be embarassed if I were an astronomer.
Well, Wiktionary claims “metal” used to mean “to mine” a few thousand years ago, so I can’t blame them that much. The astronomers at least didn’t mess up the pronunciation again :-)