Dissertation committee:
Αραμπατζής Θόδωρος , Καθηγητής, Τμήμα Ι.Φ.Ε., Ε.Κ.Π.Α.
Αραποστάθης Στάθης, Αναπληρωτής Καθηγητής, Τμήμα Ι.Φ.Ε., Ε.Κ.Π.Α.
Γαβρόγλου Κώστας, Ομότιμος Καθηγητής, Τμήμα Ι.Φ.Ε., Ε.Κ.Π.Α.
Βλαχάκης Γεώργιος, Αναπληρωτής Καθηγητής, Σχολή Ανθρωπιστικών Σπουδών, Ε.Α.Π.
Νικολαΐδης Θύμιος, Ομότιμος Διευθυντής Ερευνών, Τομέας Νεοελληνικών Ερευνών, E.I.E.
Ταμπάκης Κώστας, Κύριος Ερευνητής, Τομέας Νεοελληνικών Ερευνών, E.I.E.
Τύμπας Αριστοτέλης, Καθηγητής, Ι.Φ.Ε., Ε.Κ.Π.Α.
Summary:
Lord Rayleigh (1842-1919) was a British physicist who, for about fifty years, dealt with a wide range of classical physics as it was formed in his time, publishing more than 440 scientific articles. In addition to his research, Rayleigh held high-ranking administrative positions in several foundations and institutions during this long period. He was the second director of the Cavendish Laboratory, and later, his contribution to the establishment of the National Physical Laboratory (NPL) was vital. He also served as president of the Royal Society and the British Association for the Advancement of Science. However, a large part of Rayleigh's experiments were carried out in his private laboratory at Terling Place. This era was characterized by a transition for the experiment, which passed from the private space of experimenters to the public spaces of research centers and universities.
Experimentation was an integral element in Rayleigh's investigations, and precise measurements are at the heart of his experimental practice. Nevertheless, what constitutes accuracy in Rayleigh measurements is a complex issue.
Measurement is an activity, and accuracy, beyond a criterion of measurement reliability, is a characteristic linked to a process of corrections, processing, and discussion of data, which is part of the broader cognitive and social context. In this sense, even in the 'technical core' of measurements, there are historical, social, and cultural dimensions. Therefore, even in measurements, there are alternative scientific practices, and there may be different personal styles of scientists.
After the introductory chapter, where the topic and research questions of the dissertation are raised, in the second chapter, some historiographical and methodological elements are presented concerning measurement and accuracy in the history and philosophy of science. A brief reference is also made to research schools and scientific styles.
Then, the next chapter gives brief details of Rayleigh's biography. It attempts a rough sketch of his social and scientific profile, focusing on the aristocratic circle he belonged to, the common values and beliefs he shared with the members of that circle, and the key features of his scientific work.
The dissertation is then divided into two parts. The first part consists of four chapters. In the first of these, the fourth chapter of the dissertation, the physics laboratories that appeared in the last third of the nineteenth century are studied. Specifically, the study focuses on British and American laboratories. The place of accuracy and precise measurements is a central issue addressed in this chapter.
In the fifth chapter, attention is turned to the Cavendish Laboratory and the characteristics it acquired during Rayleigh's directorship as a center of research and teaching. A key question addressed in this chapter is whether or not there was a research faculty in the laboratory during Rayleigh's period, as well as the role of precise measurements in the laboratory during the same period.
In the next chapter, the sixth, the distinction between the concepts of 'accuracy' and 'precision,' and the meaning of these terms are traced through experimental physics textbooks, while in the seventh chapter a corresponding analysis is attempted to deal with random and systematic errors in the experimental practice of physicists in the last third of the nineteenth century.
The second part of the thesis focuses on two research projects, in the context of which Rayleigh conducted his own investigations: the determination of electrical standards and the determination of the densities of hydrogen, oxygen, and nitrogen, as well as the discovery of Argus. These programmes are chosen for four main reasons. First, these are two central investigations conducted by Rayleigh, as can be seen from the periodization of his scientific work given by his colleague, A. Schuster. Secondly, it is these investigations from which he gained his reputation as an experimenter and especially for his precise measurements. Third, both of them had accuracy as key aspect. The first programme was in the context of standardizing a unit, while the second was part of Prout's hypothesis testing, which in turn required exact measurements. Finally, both programmes had an international character, and this helped the comparative study of the scientists' experimental practices.
Specifically, the eighth and ninth chapters concern the determination of the standard and the unit of electrical resistance, and the tenth concerns the densities of hydrogen and oxygen. At the same time, the eleventh focuses on research concerning the density of nitrogen and the 'discovery' of Argon.
Through this study, it emerges that Rayleigh had a personal style with which he approached measurements, accuracy, and errors in his experimental practice. Rayleigh's style, which is analyzed in the dissertation, was not commonplace for physicists or chemists of the time. Different laboratories and scientists approached accuracy in practice differently, both at the level of teaching and research, while even the concept of accuracy itself varied across space and time.
Finally, it is argued that even among British physicists, there was variation in the approach to measurement, accuracy, and error analysis. Thus, there was no national style on this issue. On the other hand, the comparative study of Rayleigh's approach with that of the American 'academic engineers,' this hybrid type of physicist-engineer, can shed more light on the dimensions of measurement and precision.
Rayleigh and 'academic engineers' put precision at the center of their experimental practice. However, they did not approach errors and precision in the same way, particularly with regard to random errors, the method of least squares, and the calculation of probable error. The professionalization of physics and its different paths and the relationships with industry and/or astronomy have been crucial in shaping approaches to measurement, accuracy and error.
