Course summary for "Albert Einstein and the Nature of Science" Meetings 1-3: Introduction to the Nobel Prize and to the nature of science

Transcription

1 Course summary for "Albert Einstein and the Nature of Science" Meetings 1-3: Introduction to the Nobel Prize and to the nature of science The course opened with a discussion of the questions: what is science in your opinion? What are scientific theories and how do they differ from other non-science theories? What are experiments? What is their role? Does science even need experiments? Can theories be created with the absence of empirical data? Students were asked to provide examples to their answers and to comment on their colleagues' views as well. The lecturer then went on to ask questions regarding other NOS characteristics, such as: Do you think scientific theories change? That current theories might change in the future? Do you think that science is influenced by culture and society? How? Do you think scientists are creative people? Do you think that science demands creativity? Why? How is scientists' creativity expressed in their work? For each answer, the lecturer asked the students to provide some examples and to comment on other students' answers. In the first part of this lesson, no answers were provided by the lecturer. Having introduced these questions, the lecturer explained that the aim of the course is to answer them, and that we will try to do so by means of Nobel Prize stories. This was followed by another series of questions, this time concerning the Nobel Prize. What does the Nobel stand for? Who was Nobel? Why did he want to establish a fund for scientists? What are the criteria for the prize? Who can win the prize? Who decides to give the prize? What is the procedure of the prize? In what fields is the prize given? Why? Does the prize contribute to science? How? Or does it maybe discourage those scientists who do not succeeded in winning it?

2 Exposing students to so many questions without providing them with answers from the lecturer is not a conventional way of teaching in Taiwan. But it seems, from their discussion with the lecturer after the class, that the students enjoyed being heard and expressing their views. After the discussions described above, the lecturer introduced the different characteristics of NOS. He explained each characteristic, first providing an example himself and then asking for other examples from the students. The students were also asked to read Irzik and Nola's [3] paper, which criticizes the consensus approach to the teaching of NOS. We discussed this paper in class at the next meeting. The lecturer also formally introduced the Nobel Prize in a PowerPoint presentation that covered Alfred Nobel's personal life, his discovery of dynamite, his will and his reasons for establishing the fund for the prize, and the procedure for selecting laureates. The students, who were all equipped with laptops, were asked to read more about the prize on the Nobel Prize website, to get a list of the first 10 physicists who won it and to summarize the achievements for which the these first ten had won. Meetings 4-7: Albert Einstein's Nobel Prize story To open this section, the lecturer asked the students what the photoelectric effect is (a question to which all knew the answer). Then the lecturer challenged the students to explain why the prize was given to Einstein for the so simple a linear equation? What was all the fuss about? To further demonstrate how important Albert Einstein's explanation was, he asked the students to try and explain the photoelectric effect by using the wave theory, and to identify what the problem with the wave theory was. For this purpose the students could use textbooks on the wave theory.

3 The students started to work in pairs on the question. After about an hour it seemed that it was quite a challenge for them to apply what they knew on the wave theory of light to the photoelectric effect. The lecturer then briefly described the wave theory and explained how the wave theory dealt with the photoelectric effect, what it explains, what it leaves unexplained, and what contradicts the wave theory completely. Then Albert Einstein's idea, which was familiar to the students, was presented again. We went on to discuss whether or not Albert Einstein's idea was a "big idea". The lecturer presented the students with the views of leading scientists of the day who had opposed Einstein's novel idea. Then, Millikan's experiment was described and a discussion concerning the relationship between theory and evidence took place. The students were very surprised by the fact that Millikan's experiment came so many years after Einstein proposed his theory. They also found it hard to believe that Millikan also opposed Einstein's idea of light quanta. This section included an introduction to Albert Einstein the person. Who was he? Where did he live? How many children did he have? Who he was married to? What did he do, as a Jewish scientist, during World War II, his pacifism etc. Finally, the lecturer returned to the NOS characteristics that the students had learned about earlier in the course and asked the students to express their views concerning how these characteristics are manifested in Einstein's story. Meeting 8: Would Aristotle or Galileo receive a Nobel Prize? This meeting included two films from a series on History of Science called "Final for Now" ( films are in Hebrew, and were translated for the students by the lecturer. The first film describes the development of

4 the concept of heat. The lecturer asked the students what heat is. A discussion followed. Then the movie was shown, in which two actors playing Empidoculus and Aristotle discuss the meaning of heat. While Empidoculus holds the view that heat is movement, Aristotle claims that it is matter. Each of the figures provides explanations and examples for their own views. The lecturer then asked the students, "What kind of support has each of the scientists provided?", which led to a discussion of the Greek scientists' method, which was based on the logos rather than on myths and ghosts, which were accepted ways to explain scientific phenomena before the Greeks. The film then presents the views of more modern scientists concerning heat. They supported their explanations with experiments, which led to a discussion of the role of the experiment in our time and how this differs from the days of the Greek scientist. The second film was about the idea of the existence of vacuum, and in this context we conducted a similar discussion of the logos method and the role of experiments. To further discuss the role of the experiment, the following two different views were presented to the students, that of Bacon and that of Popper. According to Bacon scientific theories are developed from the observation and manipulation of nature, while according to Popper scientific theories are developed first in the head of the scientist. Popper claims that scientific theories, unlike non-scientific theories, can be tested by experiment. The discussion led the students to realize that in fact, the development of science in reality is somewhere in between these two views, that of Bacon and that of Popper. Sometimes it progresses in a path similar to that described by Bacon and sometimes it progress in a path similar to what Popper describes. It seems that there is a negotiation between theories and experiments, with neither one coming before the other.

5 Meetings 9-12: Participants' presentations and course summary The students were asked to choose and present Nobel laureate stories of their own. They chose: 1) Marie Curie (1903 in physics and 1911 in chemistry), 2) Philipp Eduard Anton von Lenard (1905 in physics), 3) Joseph John Thomson (1906 in physics), 4) Ernest Rutherford (1908, in chemistry), 5) Max Karl Ernst Ludwig Planck (1918 in physics), 6) Niels Henrik David Bohr (1922 in physics), 7) Robert Andrews Millikan (1923 in physics), 8) Arthur Holly Compton (1927 in physics), 9) Prince Louis-Victor Pierre Raymond de Broglie (1929 in physics), and 10) In addition, one student presented Newton's story and addressed the question of whether Newton would have won a Nobel Prize. The students were instructed to include the same elements in their presentations as those presented by the lecturer in the case of Albert Einstein, namely: a) The Nobel laureate's personal details: where they were born, where they were raised, information about their family, spouse and children, etc. b) The relevant physics concerning the Nobel Prize presentation. c) Why they received the Nobel Prize. d) What the accepted knowledge in their field was prior to their contribution. e) How, if at all, the different characteristics presented in the first meetings of the course emerged/manifested in the story. The students were asked to conduct discussions with the class rather than give a lecture, but - though there were some attempts to conduct discussions, the main form of student presentations were a lecture-like style, where the students strictly followed their PowerPoint presentations. It is important to note that before presenting their lectures the students had to send the PowerPoint presentation to the lecturer for

6 discussion, i.e. to receive guidance as to what should remain in it and what could be deleted, etc. As the different stories were presented, the lecturer tried to conduct discussions that compared how the different characteristics of NOS were manifested in the different Nobel laureate stories. For instance, what is the difference in how the characteristic "empirically-based" was manifested in the story of De-Broglie and the story of Rutherford. Elements of NOS in Albert Einstein's Story The story of Einstein's prize takes the students back to the period leading up to and immediately following 1905 (Einstein's 'miracle year'), as well as to 1921, the year for which his prize was awarded. Einstein's story shows us very clearly that scientific knowledge is tentative. Before Einstein's theory, physicists believed that the only valid theory of light was the wave theory. They also believed that the wave theory would eventually explain the photoelectric effect. Einstein was breaking new ground when he wrote, "According to the assumption to be contemplated here, when a light ray is spreading from a point, the energy is not distributed continuously over everincreasing spaces, but consists of a finite number of energy quanta that are localized in points in space, move without dividing, and can be absorbed or generated only as a whole" (cited in Rigden [28]). Einstein's theory was far ahead of his time, and was widely rejected by contemporary physicists. For instance, when Max Planck, in 1913, nominated Einstein for membership in the Prussian Academy of Science in Berlin, he apologized on behalf of Einstein, saying: "That sometimes, as for instance in his hypothesis on light quanta,

7 he may have gone overboard in his speculations," but that this "should not be held against him." Even after Einstein was awarded his Nobel Prize, Niels Bohr, in his own 1922 Nobel address, continued to reject Einstein's light particles. The history of Einstein's Nobel Prize thus shows not only that scientific theories are tentative, but also that the development of science is sometimes revolutionary in character [28]. The story of Einstein's prize also illustrates the NOS literature's claim that scientific knowledge is empirical. Let us first consider a letter he received, stating that "the Royal Academy of Science has decided to award you last year's Nobel Prize for physics, in consideration of your work in theoretical physics, and in particular your discovery of the law of the photoelectric effect, but without taking into account the value which will be accorded your theories of relativity and gravitation, once they are confirmed". The reservation at the end, "once they are confirmed," implies doubt as to the value to science of a theory of physics that is unsupported by empirical data an indication that the scientific community does not accept theories that are not supported by empirical evidence. However, Einstein's story also illustrates that the fact that scientific knowledge is empirical does not mean that scientists develop their theories based only on empirical data! Indeed, according to Pais 1 Einstein's path to the light quantum was not paved by experimental data: there were no data in 1905 that required light to be particulate [28]. What was known about the photoelectric effect was more or less contained in Lenard s studies in 1902, in which the latter observed that the energy of electrons liberated from a metal surface irradiated with a carbon lamp showed "not the slightest dependence on the light intensity" (quoted in Pais), even when the intensity of the light was varied a thousand-fold.

8 Physicists, intrigued by atoms and the evidence for subatomic particles, believed that the electromagnetic wave theory of light would prove sufficiently robust to provide an adequate explanation. But unlike his contemporaries, Einstein was troubled by a subtle asymmetry in the situation, namely that between the continuity of light and the discontinuity of atoms. He thought fundamental problems arise when extended light waves and point-like atoms are brought together for example, when atoms emit or absorb light. It was this juxtaposition of light and atoms that he addressed in his March paper. An interesting conclusion follows, namely that while theories may emerge in the absence of empirical evidence, and while individual scientists can develop theories using their imagination and creativity, the science community will accept these theories only if they are supported by experiments because science is empirically based. Furthermore, the fact that scientific knowledge is based on experiments does not guarantee that the existence of empirical evidence will lead to immediate acceptance of a given theory. Millikan's 1916 experiment came long after Einstein s paper, and contrary to what is often suggested in schools, Millikan did not set out to verify, even indirectly, Einstein's photon concept - he simply sought to establish the mathematical form of the relationship between the maximum energy of the ejected electron and the frequency of incident light. Moreover, even when it became clear to him that his own experimental results were in perfect agreement with the predictions made in Einstein's quantum paper, Millikan stubbornly resisted the corpuscular view of light and deplored Einstein's "bold, not to say reckless, hypothesis of an electro-magnetic light corpuscle of energy hν, which...flies in the face of thoroughly established facts of interference" (quoted by Rigden [28]). This shows that new theories are sometimes rejected even when they provide a good explanation for the empirical results! Like

9 other prominent scientists of that time, Millikan was influenced by accepted theories and was not willing to countenance Einstein's theory, even though it was backed by empirical evidence. This aptly illustrates the NOS point that scientific knowledge is theory-laden and subjective. It was only after Arthur Compton conducted his 1923 X-ray scattering experiment, in which light was seen bouncing off electrons like colliding billiard balls, that physicists finally began to accept Einstein s idea. This once again strengthens the idea that science is empirically-based, and that while theories can be developed in the absence of empirical evidence, scientists will never be satisfied with these theories until empirical evidence is found. It also illustrates the distinction noted in the NOS literature between theory and evidence. As we saw, Einstein's theory explained Millikan's experimental results, yet scientists truly believed that they could find a different and superior explanation of this same experimental data that would also be consistent/coherent with the wave theory of light and thus Einstein's theory was rejected. This means that there is a possibility that the same phenomenon may be explained by more than one theory, and also that evidence does not evolve into theories: rather, theories explain evidence, the two representing different types of knowledge. Another characteristic of science is that scientific knowledge is socially and culturally embedded. The case could be made that the photoelectric effect story is a less obvious illustration of social and cultural embeddedness than more openly controversial topics such as Darwin's theory of evolution or genetics. However, the controversy surrounding its initial acceptance does provide an opportunity for discussion. One more prominent example is Phillip Lenard, whose early experiments led to the discovery of the photoelectric effect that Einstein sought to explain, and whose belief

10 in the inherent superiority of 'German' science led him to reject Einstein's ideas because he was a Jew. The student who presented Philip Lenard's Nobel Prize story in the course also noted Lenard's later fellowship in the Nazi party, and discussed the impact of the totalitarian Nazi regime on Lenard's thinking as a scientist (see 'Results' section). 1. A. Pais, How Einstein got the Nobel Prize, Am. Sci. 70 (1982), pp