In his book, Representing Electrons, Theodore Arabatsiz tells us that at the beginning of the twentieth century, “more and more experimental situations came to be interpreted as the observable manifestations of the presence and action of Electrons.” These observable manifestations included, among others things: cathode rays, Beta-rays, the Zeeman effect, the photo-electric effect, and cloud chamber tracks.
However, we today who take the existence of the Electron for granted should remember that the scientists of the time were merely making educated guesses about the atom in order to try to explain the crazy things that their new gadgets were showing them in the laboratory. As Karl Popper said, the history of sciences is not so much “a history of theories” as it is “a history of problem situations.” New technology and methodology– and not new theories– are typically what really drives science. The theories come later (with exceptions, of course, to prove the rule).
As far as this new entity physicists were proposing, this “Electron” thing, they were really grasping in the dark. They were starting to find measurements and properties of the atomic world which they had never been able to glimpse before, and they were desperately trying– and competing with each other to be first– to explain it all. What they had were signs and hints of something which some were already starting to call an “Electron,” but which they had never actually held or beheld. As Arabatsiz tells us, “the measurement of the properties associated with an unobservable entity does not imply that this entity exists.”
Arabatsiz reminds us that in the late 1700s, many scientists were certain that they had discovered the particle which carries heat. Turns out, no such particle exists (or at least that’s the current theory), but that did not stop some of the sharpest scientific minds of the day from “measuring” and “weighing” what they were convinced was Phlogiston (the name they gave to the particle of “heat,” much as “Electron” is the name given to the supposed particle of “charge.”).
Not so dissimilarly, scientists in the late 1800s/early 1900s were convinced that they were “measuring” and “weighing” Electrons. Truth is, different experimenters were coming up with different values for Electron-mass and for Electron-charge. Personally, I was shocked upon reviewing the data– not at how different the measured Electron-values were– but at how willing scientists were to chalk up huge differences to “margin of error.” They were “finding” big electrons, small electrons, powerful electrons, weak electrons– even no electrons at all. Taking the human factor into account here (which I don’t think people do enough), my guess is that Experimenter A was willing to cut Experimenter B a lot of slack if it meant he could interpret Experimenter B’s work as supporting his own findings.
Nevertheless, with no direct observations of Electrons being made, the “Electron” which began to settle-out of this mixture of results was no more than a “statistical mean”– a thing with no more real existence than, to use Arabatsiz’s example, the “average man.”
Later scientific theories about the atom and the Electron would all but abrogate the “discovery” of the Electron as it was “measured” and “weighed” in the early days. In fact, our conception of the little mythical beastie has changed so much in the last hundred years that it is hardly the same entity at all as J.J. Thomson thought he found in the late 1800s. As Arabatzis states frankly, “there would be no legitimate sense in which all the scientists who used the term ‘Electron’ between, say, 1895 and 1925 were talking about the same thing.”