A Theory of Electrons and Protons
P. A. M. Dirac
Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, Vol. 126, No. 801 (Jan. 1, 1930), pp. 360-365
Published by: The Royal Society
Article Stable URL: http://www.jstor.org/stable/95359Comment
Interesting paper where Dirac actually proposes that electrons and protons may be a particle pair, but then dismisses it for various reasons.
In a reply to this article J.R Oppenheimer writes a letter to the editor of Phys.Rev. 35,562 (1930) where he states:
"In a recent paper, ' Dirac has suggested that the reason why the transitions of an electron to states of negative energy, which are predicted by his theory of the electron, do not in fact occur is that nearly all of the states of negative energy are already occupied. Dirac has further shown that the unoccupied states of negative energy have many of the properties of protons; that, for instance, they may be represented by wave functions which would be taken to correspond to a particle of positive charge and positive mass. He has further shown that the mass associated with these gaps is not necessarily the same as that of the electron, and he has suggested the assumption that the gaps are protons"http://journals.aps.org.ezproxy1.library.usyd.edu.au/pr/pdf/10.1103/PhysRev.35.562