The discovery of the electron was one of the most important discoveries in the history of science. Isolating this particle, along with gaining an understanding of it's properties led to further notable scientific developments. Before examining which contemporary scientist can be heralded as its discoverer it is first necessary to clarify what is meant by the term discovery. The dictionary defines this as "to be the first person to find or learn something previously unknown". The dictionary definition is a good place to start however; it is necessary to delve a little deeper than this.
David Miller gives this word a slightly different meaning when he describes discovery as "a social as well as intellectual process (2004:13)". By this he means that a would-be discoverer must make public that which he/she has discovered. This interpretation complicates any investigation into the discoverer of the electron, as publication and discovery are two separate phenomena and there would usually be a lapse in time between the actual raw discovery and a written paper being produced.
At the time that investigations into the electron were taking place the usual way of doing this was by presenting a paper or publishing a work. Today these papers make up the bulk of the evidence available to historians of science wishing to investigate a discovery. Using the original tables of results as evidence for this has two problems. Firstly they are much harder to get hold of and secondly it is only in papers officially published that the original scientists theories can be clearly identified.
In such documents the scientists presented their 'discoveries' to the world in a succinct format. Although publication came after the actual discovery, the official dates used by historians for a particular discovery are those of the papers in which the discovery was first presented. Publication of such academic works was usually only possible where the potential discoverer was carrying out his work in close proximity to centres of intellectual thought.
Furthermore in such centres of intellectual thought it is highly likely that ideas would be shared and it is easily possible that more than one person could contribute to a particular experiment or investigation. In this way each person plays a role in a discovery and can therefore claim some part in the development of an idea. Another issue that further complicates any exploration into the discovery of the electron is how far the would-be discoverer is able to realise the theoretical implications and practical applications of the discovery in a wider scientific context.
This presents three interesting possibilities for the title of discoverer. Firstly, and most simply, the one who makes the initial discovery, second the one who names the discovery or claims it for his own in published work and thirdly, and most interestingly for the scientific community in general the one who goes on to develop the idea into something more useful. Put in these terms we can certainly say that the electron was discovered. J. J. Thomson, whilst investigating cathode ray tubes, arguably made the initial discovery of the electron.
A cathode ray tube is a glass cylinder, sealed at either end, inside of which exists a vacuum and two electrodes. Cathode rays are produced when there is a voltage across the two electrodes. In his experiments Thomson showed that it was possible to redirect the rays using an electric field but that the negative charge could not be removed from them. He postulated the existence of a 'corpuscle' - a negatively charged particle. According to his theory the rays were not in fact waves but consisted of a large number of these particles. He was able to measure the mass-to-charge ratio of these particles.
Two notable details arise from his study of mass-to-charge ratios. Firstly he proved that the mass-to-charge ratio was unaffected both by the gas initially in the tube and the material used for the cathodes. Thus he construed that these 'corpuscles' were found in all materials and not given off by a particular substance. Secondly he found the mass-to-charge ratio to be minute: more than a thousand times smaller than that of a hydrogen ion. This led Thomson to come up with two possible theories; either these particles were very small in mass or very highly charged.
During the 19th century there had been a shift in the socio-economic nature of science. Up until this time science had been a pursuit dominated by the wealthy aristocracy. It was particularly hard for someone from a modest background to gain notoriety in this field as new discoveries relied on testament: If someone was of a sufficient social order their discovery or theory would be accepted. However, by the end of the 19th century sufficient change had taken place within the scientific community that this was no longer the case.
Instead the emphasis was now on evidence to support ones argument and science had become more accessible to those from all castes. Thomson himself is a fine example of the new breed of scientist no longer exclusively from the upper echelons of society: His father had been a modest bookseller who had died at the end of Thomson's second year at Owens College.
Thomson had intended to pursue a career as an engineer but could not afford the apprenticeship due to the death of his father but instead won a scholarship to study at Trinity College Cambridge (Chayut, 1991, p. ). Here Thomson carried out his investigations; in the Cavendish Laboratory. This is undoubtedly a centre of intellectual thought, indeed one of the most prestigious ones in the world. This combined with the opening up of science to all classes allowed Thomson to easily and swiftly publish his findings in 1897. Thomson can clearly be seen to be filling the first two descriptions of a discoverer: He identified the existence of the particle and published his findings. However there are two obvious ways in which Thomson can be seen not satisfying the third possibility.
Firstly after his further measurement of the Mass-to-charge ratios, which he found to be incredibly small, he put forward two possible reasons for this tiny value. Either the 'corpuscle' was incredibly small or it was very highly charged. It was only later experiments by other scientists that concluded the former. Secondly his plum-pudding model clearly shows he was unaware of the significance of the electron in a wider scientific context. Even in a paper he published two years later he was unable to conclude anything more than "there are a considerable number of corpuscles in the atom" (J. J. Thomson, 1899, page 567).
Many would argue that because of this he cannot be credited with the discovery of the electron. Furthermore he was carrying out his work in a way in which experimentation was at the forefront: There was no accepted theory or hypothesis that he was trying to prove or disprove. This is one argument against Thomson as the discoverer. However, such is the nature of discovery. When Columbus and Cook discovered America and Australia respectively they were not trying to prove or disprove that these places existed.
They merely set out with the intention of finding out what was there. The same can be said of Thomson's work. It is the case that Thomson did not design the techniques and equipment he used himself. Other scientists such as Robert Millikan and William Crookes in fact conceived these. This argument would support a view that "the establishment of the electron as a physical entity represented the culmination of long traditions in physics" and was not in fact discovered at all, let alone by Thomson (Buchwald and Warwick, 2001, page 4).
However this is part of the interesting pursuit that is science: Ideas developed by earlier scientists influence and assist later scientists in their work. This is true even today and was also the case for Thomson. His work in discovering the electron undoubtedly helped lead to the development of the new atomic structure and the wider appreciation of the role played by the electron in science generally. In conclusion, it is possible to say that the electron was 'discovered'. It was isolated as an individual entity and scientific evidence to support its existence was published.
The man correctly credited with its discovery was Joseph John Thomson. Whilst much work was later carried out to ascertain the broader significance, in science generally, of this particle its discovery rests with Thomson. This later work certainly has great importance to the scientific community as a whole but represents separate 'discoveries' worthy of individual recognition. For example Ernest Rutherford, one of Thomson's students, went on to produce the orbital theory of the atom due to his work with gold foil.
He, like Thomson, went on to win a Nobel Prize. His worked was undoubtedly influenced by that of Thomson yet it would be unfair to credit Thomson with this discovery too; even though he certainly contributed to it. Ultimately due to the ever developing nature of science many can contribute in some way to an investigative piece of work but the final discovery will be credited to the one (or sometimes two in the case of DNA) who makes the recognisable final step and is then able to publish their findings for the world to see.