The most famous document in neutrino physics is the letter Wolfgang Pauli sent explaining the idea for the particle.  It begins “Dear Radioactive Ladies and Gentlemen,” and due to his embarrassment at proposing something that seemed crazy and probably not-observable he gives an excuse for not attending the meeting in person:

“Unfortunately, I cannot personally appear in Tübingen since I am indispensable here in Zürich because of a ball on the night from December 6 to 7.”

No such reticence occurs today (also physicists don’t usually attend balls due to their typically poor waltzing skills).

Symmetry Magazine had a nice picture and exposition of the original letter, explaining what various parts mean, and Kurt Riesselmann’s translation from that article is below.

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Physics Institute of                                          Zürich, Dec. 4, 1930
the ETH Zürich

Dear Radioactive Ladies and Gentlemen,

As the bearer of these lines, to whom I graciously ask you to listen, will explain to you in more detail, because of the “wrong” statistics of the N- and Li-6 nuclei and the continuous beta spectrum, I have hit upon a desperate remedy to save the “exchange theorem” (1) of statistics and the law of conservation of energy. Namely, the possibility that in the nuclei there could exist electrically neutral particles, which I will call neutrons, that have spin 1/2 and obey the exclusion principle and that further differ from light quanta in that they do not travel with the velocity of light. The mass of the neutrons should be of the same order of magnitude as the electron mass and in any event not larger than 0.01 proton mass. – The continuous beta spectrum would then make sense with the assumption that in beta decay, in addition to the electron, a neutron is emitted such that the sum of the energies of neutron and electron is constant.

Now it is also a question of which forces act upon neutrons. For me, the most likely model for the neutron seems to be, for wave-mechanical reasons (the bearer of these lines knows more), that the neutron at rest is a magnetic dipole with a certain moment μ. The experiments seem to require that the ionizing effect of such a neutron can not be bigger than the one of a gamma-ray, and then μ is probably not allowed to be larger than e • (10-13cm).

Therefore one should seriously discuss every way of rescue. Thus, dear radioactive people, scrutinize and judge.

 

I admit that my remedy may seem almost improbable because one probably would have seen those neutrons, if they exist, for a long time. But nothing ventured, nothing gained, and the seriousness of the situation, due to the continuous structure of the beta spectrum, is illuminated by a remark of my honored predecessor, Mr Debye, who told me recently in Bruxelles: “Oh, It’s better not to think about this at all, like new taxes.” Therefore one should seriously discuss every way of rescue. Thus, dear radioactive people, scrutinize and judge. – Unfortunately, I cannot personally appear in Tübingen since I am indispensable here in Zürich because of a ball on the night from December 6 to 7. With my best regards to you, and also to Mr. Back, your humble servant

signed W. Pauli