Editing Timeline of nuclear fusion (section)

==1920s==
* '''1920'''
** Based on [[F.W. Aston|F.W. Aston's]] measurements of the masses of low-mass elements and [[Albert Einstein|Einstein's]] discovery that <math>E=mc^2</math>, [[Arthur Eddington]] proposes that large amounts of energy released by [[nuclear fusion|fusing]] small nuclei together provides the energy source that powers the stars.<ref>{{Cite journal |last=Eddington |first=A. S. |date=1920 |title=The Internal Constitution of the Stars |url=https://www.jstor.org/stable/1645153 |journal=Science |volume=52 |issue=1341 |pages=233–240 |issn=0036-8075}}</ref>
** [[Henry Norris Russell]] notes that the relationship in the [[Hertzsprung–Russell diagram]] suggests a hot core rather than burning throughout the star. Eddington uses this to calculate that the core would have to be about 40&nbsp;million Kelvin. This was a matter of some debate at the time, because the value is much higher than what observations suggest, which is about one-third to one-half that value.
* '''1928'''
** [[George Gamow]] introduces the mathematical basis for [[quantum tunnelling]].<ref>{{cite book |title=Compendium of Quantum Physics |publisher=Springer |first1=G. |last1=Nimtz |first2=B. |last2=Clegg |date=12 August 2009 |editor-last1=Greenberger |editor-first1=D. |editor-last2=Hentschel |editor-first2=K. |editor-last3=Weinert|editor-first3=F. |isbn=978-3-540-70622-9 |pages=799–802}}</ref>
* '''1929'''
** [[Robert d'Escourt Atkinson|Atkinson]] and [[Fritz Houtermans|Houtermans]] provide the first calculations of the rate of nuclear fusion in stars. Based on Gamow's tunnelling, they show fusion can occur at lower energies than previously believed. When used with Eddington's calculations of the required fusion rates in stars, their calculations demonstrate this would occur at the lower temperatures that Eddington had calculated.<ref>{{cite journal|last1=Atkinson|first1=R. d E.|last2=Houtermans|first2=F. G.|title=Zur Frage der Aufbaumöglichkeit der Elemente in Sternen|journal=Zeitschrift für Physik|date=1929|volume=54|issue=9–10|pages=656–665|doi=10.1007/BF01341595|bibcode = 1929ZPhy...54..656A |s2cid=123658609}}</ref>