When we are taught the history of physics, it is quite common for major discoveries to be introduced in an abbreviated form that loses much of the very interesting context. We are told “Scientist X discovered Y in year XXXX,” but are often not told about the tortured path of investigations that lead up to Y and the numerous questions that were answered by the new discovery.
A great example of this is the discovery of the electron! The electron was officially discovered in 1897 by British physicist J.J. Thomson using experiments on cathode rays (mysterious “rays” emanating from the cathode in a vacuum tube), in which he was able to estimate both the mass and the charge of electrons. That description is quite abridged, however, and there was a long philosophical discussion about the existence of electrons preceding its discovery and a lot of mysteries that were suddenly unraveled by its existence.
I was thinking about this a lot recently due to two factors. The first is that I wrote a blog post on an early inadvertent test of special relativity investigating the apparent mass of electrons. That paper by Kaufmann gave me a sense of how radical the discovery of the electron was at the time and how eager people were to determine all of its properties. The second factor was… a mistake? Kaufmann’s relativity paper came out in 1901, and was in German, and was about electrons; my first attempt to track it down led me to a 1901 paper by Kaufmann in German about electrons, and I started translating it. About halfway through translation, I realized that the paper was not the one I was looking for, but it was so interesting that I finished translating it anyway!
The paper in question was a public lecture that Walter Kaufmann wrote on “The development of the concept of electrons,” and it is a timely overview of the history of the concept and everything that had been learned since its formal discovery! It is such an interesting read I thought I would share my translation in its entirety in this blog post, with my own annotations and explanations to provide context when needed.
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Skulls in the Stars 