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What's the third most common element?

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Re: What's the third most common element?

#41

Post by SquareWheel »

gpvos wrote: post #19
ghubbard wrote: post #3

What's the third most common element (in the universe)? tl;dr: Oxygen But it's worth reading the article to learn why.

Note that the very interesting graph near the end of the article actually displays element abundance in the solar system, not in the universe. (Found that out when looking it up in Wikipedia.) The article misrepresents this!

I also searched it up on Wiki. They have a larger version of the image, and a data source.

Link: http://commons.wikimedia.org/wiki/File:Nucleosynthesis_perio...

Re: What's the third most common element?

#42

Post by gjm11 »

sltkr wrote: post #12
maaaats wrote: post #7

Earlier quoted context omitted.

Please just downvote the comment instead. ;)

I think in cases where the original comment appears to be made in good faith, it's OK to explain what's wrong with it/what to do instead. That's how people learn. (Obvious spam/flames/etc. should just be downvoted, ofcourse.)

Yup.

It seems like about half of ilovefood's comments are of the "wow! great article!" type. I'm not sure whether this indicates that comments saying "don't do that" are likely to be helpful or not...

(If it were 100%, I'd conclude that it's a would-be spammer's account, building up a bit of history before starting to try to fill HN with spam. But I don't think that's what's going on here.)

Re: What's the third most common element?

#45

Post by jigg4joe »

dannypgh wrote: post #27
raverbashing wrote: post #16

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Water#In_the_universe While water will break down at high temperatures I would find it surprising that 1st and 3rd most common elements in the whole universe, that readily combine to form water would not result in substantial amounts of water. It's probably like saying we shouldn't find H2 because "nothing says they are found bound together"

Most atoms- and certainly most hydrogen- are in stars, no? Not exactly places where water "breaking down at high temperatures" (really, never forming) can be ignored.

Most hydrogen (and baryonic mass in the universe) is in the interstellar/intergalactic gas clouds

Re: What's the third most common element?

#46

Post by autokad »

natejenkins wrote: post #11

What caught my eye was the oscillation in the abundancy graph, there is a tendency for even atomic number elements to be more abundant than odd atomic number elements. Looking at the original Wikipedia article leads to the Oddo-Harkins rule http://en.wikipedia.org/wiki/Oddo%E2%80%93Harkins_rule . There is more discussion on the stability of even vs odd atomic number elements here: http://en.wikipedia.org/wiki/Even_an…

when you roll 2 dice, you get a lot more evens than odds.

i imagine the same principle holds. if an odd (Hydrogen) forms with another odd, you get even. Hydrogen+helium=odd, but helium + helium = even. as the evens outnumber the odds, even more evens are forming with evens.

Re: What's the third most common element?

#47

Post by andrewingram »

simonh wrote: post #26
mrfusion wrote: post #24

I've always wondered how elements produced in past stars end up in our solar system. I wouldn't think the whole universe is getting remixed all the time. It seems like areas stay pretty isolated.

At the universal scale, we can observer several galaxies in various stages of colliding with each other (1). In fact our galaxy and Andromeda are on course to collide with each other in about 4 billion years (2). Massive stars end their lifecycle in a supernova explosion, which blasts much of their mass off into space. the remaining stellar core either forms a neutron star or a black hole. The mass that is blated off…

Assuming I remember correctly, I should clarify that specifically it's the supernova itself that produces the heavy elements. The fusion that occurs during the bulk of the star's life doesn't tend to get much beyond oxygen.

Re: What's the third most common element?

#48

Post by Someone »

autokad wrote: post #46
natejenkins wrote: post #11

What caught my eye was the oscillation in the abundancy graph, there is a tendency for even atomic number elements to be more abundant than odd atomic number elements. Looking at the original Wikipedia article leads to the Oddo-Harkins rule http://en.wikipedia.org/wiki/Oddo%E2%80%93Harkins_rule . There is more discussion on the stability of even vs odd atomic number elements here: http://en.wikipedia.org/wiki/Even_an…

when you roll 2 dice, you get a lot more evens than odds. i imagine the same principle holds. if an odd (Hydrogen) forms with another odd, you get even. Hydrogen+helium=odd, but helium + helium = even. as the evens outnumber the odds, even more evens are forming with evens.

No, you don't 1+3+5+5+3+1 = 2+4+6+4+2

(1/36 probability of a sum of 2, 3/36 of a sum of 4, etc)

Re: What's the third most common element?

#49

Post by gpvos »

raverbashing wrote: post #29
weego wrote: post #22

Earlier quoted context omitted.

You provided a conjecture based on incomplete data as fact, he stated that it's conjecture until additional data to support it is there... the burden in this situation is not on him.

> You provided a conjecture based on incomplete data as fact, No, I never said it is a fact, it is, as you pointed, a conjecture, and I provided a source (ok, wikipedia) for the amount of water in the universe If you or him knows of a reason for why the most common elements in the universe that combine easily wouldn't result in an abundance of their combination I'm all ears. (Which doesn't mean the amount of water is…

Yeah, I was a bit out of line there, sorry. It is pretty common knowledge that H and O combine easily.

Re: What's the third most common element?

#50

Post by gpvos »

SquareWheel wrote: post #41
gpvos wrote: post #19

Earlier quoted context omitted.

Note that the very interesting graph near the end of the article actually displays element abundance in the solar system, not in the universe. (Found that out when looking it up in Wikipedia.) The article misrepresents this!

I also searched it up on Wiki. They have a larger version of the image, and a data source. Link: http://commons.wikimedia.org/wiki/File:Nucleosynthesis_perio...

And the one that I actually meant: https://commons.wikimedia.org/wiki/File:SolarSystemAbundance...
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