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Adding short description: "Discrepancy between the observed abundance of lithium produced in Big Bang nucleosynthesis and the amount that should theoretically exist." (Shortdesc helper) |
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{{short description|Discrepancy between the observed abundance of lithium produced in Big Bang nucleosynthesis and the amount that should theoretically exist.}}
In [[
==Origin of lithium==
One day after the Big Bang the universe was made almost entirely of hydrogen and helium, with only very small amounts of the next three elements—lithium (Li), beryllium (Be), and boron (B).<ref name="habitable">
===The P-P II branch===
Lithium is made by a proton-proton chain reaction
[[File:Proton-Proton II chain reaction.svg|thumb|Proton–proton II chain reaction]]
{{See also|Lithium burning}}
<!-- Autogenerated using Phykiformulae 0.11 by [[User:SkyLined]]
He-3 + He-4 -> Be-7 + y
Be-7 + e- -> Li-7 + ve (0.861MeV/0.383MeV)
Li-7 + H -> 2He
-->:{| border="0"
|- style="height:2em;"
|{{nuclide|link=yes|helium|3}} ||+ ||{{nuclide|link=yes|helium|4}} ||→ ||{{nuclide|link=yes|beryllium|7}} ||+ ||{{SubatomicParticle|link=yes|Gamma}}
|- style="height:2em;"
|{{nuclide|link=yes|beryllium|7}} ||+ ||{{SubatomicParticle|link=yes|Electron}} ||→ ||{{nuclide|link=yes|lithium|7|charge=-}} ||+ ||{{SubatomicParticle|link=yes|Electron Neutrino}} ||+ ||{{val|0.861|u=MeV}} ||/ ||{{val|0.383|u=MeV}}
|- style="height:2em;"
|{{nuclide|link=yes|lithium|7}} ||+ ||{{nuclide|link=yes|hydrogen|1}} ||→ ||2 {{nuclide|link=yes|helium|4}}
|}
The P-P II branch is dominant at temperatures of 14 to {{val|23|u=MK}}.
Models of the collisions that would have occurred found that there would have been one helium atom for every ten hydrogen atoms which fits with the observations of young stars.<ref name="habitable">{{cite book |isbn=978-0691140063}}</ref>
[[File:Stable nuclides H to B.png|thumb|center|800px|Stable nuclides H to B]]▼
==Observed abundance of lithium==
Despite the low theoretical abundance of lithium, the actual observable amount is three times less. This contrasts with the observed abundance of isotopes of [[hydrogen]] (<sup>1</sup>H and [[deuterium|<sup>2</sup>H]]) and [[helium]] ([[helium-3|<sup>3</sup>He]] and [[helium-4|<sup>4</sup>He]]) that are consistent with predictions.<ref name=HouStats/>
[[Image:SolarSystemAbundances.svg|thumb|center|800px|Abundances of the chemical elements in the Solar System. Hydrogen and helium are most common, residuals within the paradigm of the Big Bang.<ref>{{cite book |last1=Stiavelli |first1=Massimo |year=2009 |title=From First Light to Reionization the End of the Dark Ages |url=https://books.google.com/books?id=iCLNBElRTS4C&pg=PA8 |page=8 |publisher=[[Wiley-VCH]] |___location=Weinheim, Germany |isbn=9783527627370}}</ref> Li, Be and B are rare because they are poorly synthesized in the Big Bang and also in stars.]]
▲[[File:Stable nuclides H to B.png|thumb|Stable nuclides H to B]]
==Proposed solutions==
This deficiency of lithium may in part be due to faster destruction than synthesis of <sup>7</sup>Li and its progenitor [[beryllium-7|<sup>7</sup>Be]] in [[nuclear reaction]]s, though no conclusive results on the reaction flow in Big Bang nucleosynthesis have been obtained. Newer theories involving physics beyond the [[standard model]], involving not well understood [[dark matter]], have also been proposed to explain the possible destruction of lithium, also inconclusively.<ref name=Bertulani>{{cite journal |last=Bertulani |first=C.A. |last2=Shubhchintak |last3=Mukhamedzhanov |first3=A.M. |title=Cosmological lithium problems |date=2018 |journal=The European Physical Journal Conferences |volume=184 |doi=10.1051/epjconf/201818401002 |arxiv=1802.03469}}</ref><ref name=MWoo>{{cite web |url=http://www.bbc.com/earth/story/20170220-the-cosmic-explosions-that-made-the-universe |title=The Cosmic Explosions That Made the Universe |last=Woo |first=Marcus |date=21 Feb 2017 |website=earth |publisher=BBC |access-date=21 Feb 2017 |quote=A mysterious cosmic factory is producing lithium. Scientists are now getting closer at finding out where it comes from |deadurl=no |archiveurl=https://web.archive.org/web/20170221214442/http://www.bbc.com/earth/story/20170220-the-cosmic-explosions-that-made-the-universe |archivedate=21 February 2017 |df=dmy-all }}</ref>
==See also==
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