Big Bang ruled out as origin of lithium-6

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Bob Enyart said:
the long-accepted answer is now increasingly rejected: that zinc, silver, gold, etc., were said to be formed by supernovas.

It's worth noting that this "long-accepted answer" was always a best guess based on the limited evidence then available. The fact that more evidence is causing scientists to re-evaluate the guess is not a "red flag" that the BBT is wrong; if it turns out that neutron star mergers, rather than supernovas, are what formed the elements heavier than iron, that doesn't invalidate other parts of the BBT; it just becomes a better-tested part of the same overall theory.
 
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Bob Enyart said:
Guys, something I think we've glossed over in this whole thread is that the paper we've been talking about deals with actually a second lithium issue. The more traditional cosmological lithium problem, I think, is not this current isotope ratio problem, but simply a lithium problem.

An update on this first problem appeared this year in a paper in the Monthly Notices of the Royal Astronomical Society. Regardless of isotopes, the amount of observed lithium where theory attributes it to the big bang itself is apparently inconsistent with big bang nucelosynthesis (BBN). Earlier, a secondary assumption was that the inconsistency was possibly a "local problem", perhaps only manifesting itself in our own or similar galaxies. So the authors asked:

...is the Li problem a local problem, limited to our Galaxy, or is it independent of the environment? The analysis of the RGB stars in M54 confirms the findings in ω Centauri (Monaco et al. 2010), considered as the remnant of an accreted dwarf galaxy: the Li problem seems to be an universal problem, regardless of the parent galaxy.​

Thus Mucciarelli, et al., conclude:

Our result shows that this discrepancy is a universal problem concerning both the Milky Way and extra-galactic systems. Either modifications of BBN calculations, or a combination of atomic diffusion plus a suitably tuned additional mixing during the main sequence, need to be invoked to solve the discrepancy. MNRAS, 2014​

So it appears that BB predictions have led to two different lithium issues.

There is only one lithium problem.

I went into incredible detail above, providing a heap of references to approaches to solving the 7Li problem. You will note that only one option involves "new physics", and none of them are anything like getting rid of BBN. Glossed over, indeed! I heavily suggest you read Brian Fields 2011 review paper, that I linked above.

https://dl.dropboxusercontent.com/u/34677838/lithiumproblem.bib , for everything I've got on the 7Li problem, beyond what I referred to above. I don't pretend it's complete, and it is skewed towards nuclear solutions, but it may help to enlighten.
 
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PeterDonis said:
It's worth noting that this "long-accepted answer" was always a best guess based on the limited evidence then available. The fact that more evidence is causing scientists to re-evaluate the guess is not a "red flag" that the BBT is wrong; if it turns out that neutron star mergers, rather than supernovas, are what formed the elements heavier than iron, that doesn't invalidate other parts of the BBT; it just becomes a better-tested part of the same overall theory.

Definitely. And it's really not a settled question yet - we're not sure that the rate of neutron star mergers is enough. But it's important to note that supernovas aren't really ruled out either. Supernova models are hard! We're only just being able to actually get them to explode reliably!

Open questions aren't bad, or signs that a theory is wrong, they're opportunities to help us refine our models.

ETA: And I'm afraid I've got little idea as to what supernova explosions have to do with the validity of BBN, except for the general theme of nucleosynthesis. Help?
 
To you who knew so much about the current Li situation, thanks for a valuable thread! I learned a lot, obviously.

Now this:

Bob Enyart said:
I think that Drakkith has stated the matter so clearly that for this thread I'm content to let his be the last word:

QFT? Or is it an implication of that something I said wasn't correct? I can't tell.

But FWIW, and it is quite clearly straying from the topic of BBN, that constraint is going into the testing, which was successful. Some day it may itself be predicted (explained), but we aren't there yet.

As noted already:

e.bar.goum said:
Open questions aren't bad, or signs that a theory is wrong, they're opportunities to help us refine our models.

Even more, open questions is a sign of a productive area of inquiry. Science for the win, literary.
 
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