Veamos como Dirac describe su gran descubrimiento:
There was some modifications needed in the Klein-Gordon equation. I puzzled over it for a time and eventually I was able to think of another equation which would get over the logical difficulties of the negative probabilities. I soon saw that this new equation gave correctly the spin and the magnetic moment of the electron. That was very satisfactory.
Vean que daba cuenta de dos fenómenos que se estaban explorando: el spin y el momento magnético (yo tiendo a olvidar que eran DOS fenómenos que podía explicar, no solamente el spin).
The question then arose, would it satisfactorily explain the spectrum of hydrogen?...
Creo recordar que no fue en el artículo original donde desarrolló este resultado, fue mas bien espoleado por la pregunta de un físico.
...I worked that out, taking account only the first order of accuracy for the relativistic corrections, and I got agreement with experiment to this first order. The natural thing to do then would be to examine the higher orders and see whether they would also agreement with experiment. But I did not do it, simply because I was scared. I was afraid that maybe they would not come out right. Perhaps the whole basis of the idea would have to be abandoned if it should turn out that it was not right to the higher orders and I just could not face that prospect...
Curiosa actitud de Dirac, que otras veces se mostró más confiado en la fuerza de sus ideas.
.... So I hastly wrote up a paper giving the first order of approximation and showing that to that accuracy, at any rate, we had agreement between the theory and observation. In that way I was consolidating a limited amount of success, that would be something which one could stand on independently of what the future would hold. One very much fears the need for some consolidated success under circumstances like that, and I was in a great hurry to get this first approximation published before anything could happen which might just knock the would thing on the head.
Fue un nieto de Charles Darwin, Charles Galton Darwin, quien daría ese paso.
It was left to Darwin to fill up the gap that I left. Darwin, you see, was able to approach the subject without having any fears. He made the necessary calculations to all orders of accuracy and found that they fit, and I was very relieved to hear about it.
Ver algo de la ecuación de Dirac en:
donde aparece mencionado un término denominado "de Darwin". Ver también:
Angel "Java" Lopez