Editing Nuclear physics (section)

===Eddington and stellar nuclear fusion===
Around 1920, [[Arthur Eddington]] anticipated the discovery and mechanism of [[nuclear fusion]] processes in [[star]]s, in his paper ''The Internal Constitution of the Stars''.<ref name=eddington>{{cite journal |last=Eddington |first=A. S. |title=The Internal Constitution of the Stars |journal=The Scientific Monthly |volume=11 |issue=4 |year=1920 |pages=297–303 |jstor=6491|bibcode=1920SciMo..11..297E }}</ref><ref name=eddington2>{{cite journal|bibcode=1916MNRAS..77...16E|title=On the radiative equilibrium of the stars|journal=Monthly Notices of the Royal Astronomical Society|volume=77|pages=16–35|last1=Eddington|first1=A. S.|year=1916|doi=10.1093/mnras/77.1.16|doi-access=free}}</ref> At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was [[nuclear fusion|fusion]] of hydrogen into helium, liberating enormous energy according to Einstein's equation ''[[Mass–energy equivalence|E = mc<sup>2</sup>]]''. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of [[hydrogen]] (see [[metallicity]]), had not yet been discovered.