Biography_Democritus_ENG.pdf Biography: Democritus 1 Storytelling Teaching Model: wiki.science-stories.org Biography: Democritus Democritus (460 – 370 BC) was a Greek philosopher and thinker. Known as the “laughing philosopher,” he was a supporter of extreme determinism and a main proponent of ancient materialism. Around 430 BC he presented an atom- ic theory of the cosmos and is now considered to be the “father of the materia- list theory of matter and modern science.” Democritus, like many of his contemporaries, did not leave behind written works. However, from the messages of later Greek authors, we know with some certainty that he was born around 460 BC in Abdera, Thrace, though some historians believe that it was actually closer to the year 490 BC. He died around 370 BC. When he was young, he was educated by Egyp- tian priests and Babylonian magicians. In subse- quent years, he studied philosophy in Leucippus' school (school of Atomists, 400 BC), where he de- veloped an interest in atomic theory. He inherited a vast sum of money from his fa- ther and was able to travel abroad. He spent many years travelling to Egypt, the Babylonian Empire, India, Persia, and Athens. During his travels he was able to meet many astrologers, Egyptian priests, scholars of Babylon, and philosophers from India. Thanks to them he gained a tremen- dous amount of knowledge. We estimate that Democritus wrote about 70 different works, but only a few of them have sur- vived to this day. The majority of his works are about mathematics, biology, sociology, geography, astronomy, meteorology, economics, scenography, and the theory of language. Although we know little about his life, we have discovered quite a lot about his views. Unlike the Eleatics, Democritus believed, that besides a state of being, there must be a void (called the vacuum). According to Democritus, all matter consists of tiny, indivisible particles called atoms (from the Greek atom or atomos, meaning “indivisible”), which are moving in a vacuum. The motion of atoms, and their combination and sepa- ration, are the basis for every observable phenom- enon. Atoms cannot be destroyed, because they are not able to disappear or be created. Therefore, according to his theory, the world does not have a beginning or an end. Democritus believed that the motion of atoms is not accidental, but subject to the laws of nature. From this it follows that every- thing that happens has a reason, and every phe- nomenon is inevitable. Democritus assumed that different types of atoms exist and by describing these different types, he could explain the differences between objects. According to him, different objects are made of a different number of various atoms. For example, the soul that animates living objects is made of fire, consisting of smooth, light, and round atoms. In contrast, an evil person is made of heavy, rough atoms. He also thought that liquids consisted of smooth, rounded atoms, which caused them to fall apart. Solid objects, on the other hand, were made of rough, cogged atoms able to hook onto each other. Much like he did with the three states of matter, Democritus used the concept of atoms to explain the differences in what we taste and see. According to his theory, large, rounded atoms gave a sweet taste, and heavy, rough atoms gave a spicy flavor. Colors and shades are also dependent on the position of atoms in a mixture. Democritus believed that the atoms that make up everything on Earth, as well as all planets and stars, are always and forever the same. Atoms can combine in a void and create everything from rocks, to plants and animals. When the entities die, the atoms are released and combine with each other to create new things. This idea was not ap- preciated by the scholars of that time, although it was confirmed many centuries later by a French chemist named Antoine Lavoisier. This idea is now one of the basic laws in the natural sciences. The views circulated by Democritus were not widely accepted, as the popular philosophers at the time (such as Socrates, Plato, and Aristotle) were interested in philosophical concepts and the hu- man body, not in the nature of matter or atoms. Due to this difference in interests, Plato never 2 Biography: Democritus Storytelling Teaching Model: wiki.science-stories.org mentioned Democritus’ name, although he de- scribed some of his views. It is believed that Plato even wanted to burn Democritus’ works, but the followers of the Pythagorean cult (Cleinias and Amyclas) prevented this from happening. Aristotle was another philosopher who did not support atomism, but he spoke glowingly of Democritus, believing that Democritus had put thought into his reasoning. He was also impressed by the ample scientific method that Democritus had used. With the fall of Greek civilization, the theory of atomism did not develop further for a long time. Democritus’ ideas were forgotten and were viewed as a false doctrine, or a spurious path leading to atheism. Alchemy was still present in the second centu- ry, but it was collection of nonsensical, fantastic tales, magic formulas, and recipes full of symbols, strange metaphors and quackery. Its main purpose was to abuse uneducated people. In this chaos, it was extremely hard to find reliable data, so we cannot be sure what scientific theories existed in that time. These theories were formulated based on primitive experiments and were connected to philosophical hypotheses of past centuries regard- ing matter, states, and characteristics. It was not until the early 19th century that Democritus’ hypothesis experienced a renaissance when an English chemist named John Dalton an- nounced his theory of atomism, on a new, more realistic basis. Scholars throughout history believed that Democritus was not only ingenious, but the most important scholar prior to Aristotle. References Fierz-Dawid, H. E., (1958). Historia rozwoju chemii. Warsza- wa: Państwowe Wydawnictwo Naukowe. http://www.encyklopedia.pwn.pl http://www.britannica.com http://www.portalwiedzy.onet.pl http://www.wikipedia.pl Wróblewski, A. K., (2007). Historia fizyki. Warszawa: PWN. Wróblewski, A. K., (1998). Wiedza i Życie. Biography: Democritus was edited by Stephen Klassen and Cathrine Froese Klassen and is based, in part on Historical Background: Atoms written by Peter Heering. Biography: Democritus was written by Emilia Dobrowolska with the support of the European Commission (project 518094-LLP-1-2011-1-GR-COMENIUS-CMP) and Polish Association of Science Teachers, Poland. This publication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein. EN_Guidelines_Democritus.pdf Suggestions to Teachers (Democritus and the atoms) 1 Storytelling Teaching Model: http://science-story-telling.eu Suggestions to Teachers (Democritus and the atoms) Expected results After the lesson, the students are expected to: 1. Locate the Plato’s views and Democritus’ views about the structure of matter and the vacuum. 2. Write the important differences between the Democritus’ views and the Plato’s views. 3. Make inquiry in the web and create a written text concerning the current scientific views about the structure of matter. 4. Locate the role played by religious beliefs of people in the medieval times, which made Aristotle’s view prevail and Democritus’ view be overlooked. 5. Write the reasons Aristotle’s theory prevailed over the structure of matter for many years, based on the lesson activities. 6. Demonstrate the diachronism of scientific questions about the structure of matter. About the activities of students The proposed students' activities are indicative and they aim at the accomplishment of the above expected outcomes. Moreover, the teacher may choose some of them for the teaching process in relation to its aims, the needs of students and the available time. Finally, she/he can create her/his own activities. About the emergence of the characteristics of science in the narration, these characteristics are quoted in the website, comprehensively (in classification of the stories by NOS). About the locating of the characteristics of Nature of Science in the proposed activities, indicatively, we can quote the following: A) In the activity 3, the case 1 concerns the characteristic of Nature of Science: “There are historical, cultural, and social influences on science” and the case 4, concerns the characteristic: “Science demands and relies on empirical evidence”. B) The activity 5 concerns the characteristic of Nature of Science: “Scientific knowledge is tentative but durable”. C) The activity 6 concerns the characteristic of Nature of Science: “Science demands and relies on empirical evidence”. 2 Suggestions to Teachers (Democritus and the atoms) Storytelling Teaching Model: http://science-story-telling.eu Suggestions to Teachers (Democritus and the atoms) were written by Aikaterini Rizaki and Panagiotis Kokkotas with the support by the European Commission (Project 518094-LLP-1-2011-1-GR-COMENIUS-CMP) and the NKUA of Greece. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained there in. EN_LA_Democritus.pdf Student’s Learning Activities (Democritus and the atoms) 1 Storytelling Teaching Model: http://science-story-telling.eu Student’s Learning Activities (Democritus and the atoms) Activity 1 You will watch a video with narration or listen to a story from your teacher about the ancient philosophers Democritus and Plato. Please write down the main points of the story, and discuss about them in your group. (Indicative important points of the story: Plato's views about the material bodies, the atomic theory of Democritus,..…) The most important points of the views of Democritus and Plato about the structure of matter are: Α) Atomic theory of Democritus ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………..………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………… Β) Plato's views about the material bodies ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………… C) Please compare the views of Democritus and Plato about the vacuum. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… 2 Student’s Learning Activities (Democritus and the atoms) Storytelling Teaching Model: http://science-story-telling.eu ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… …………………… Activity 2 Based on the text below please highlight and discuss in your group the factors that contributed to the prevalence of Aristotle’s view. «Plato’s perceptions about the structure of matter i.e. that the world consisted of four elements: water, air, fire and earth, were supported by Leucippus and Aristotle. Aristotle added a fifth element the aether, which fills the space between the heavenly bodies. Democritus’ perceptions were not accepted by his contemporaries for two reasons because: a) the called “atoma” were not visible, so there was no proof for their existence and b) Aristotle's theory could explain his observations based on the above principles, whereas atomists were not able to offer a convincing explanation for the existence of particles that no one could see. This was a significant point of criticism of Aristotle against the atomic theory, beyond the fact that he himself did not accept the idea of empty space, which according to his perception was impossible to exist. The view of the supporters of the existence of permanent motion (constant movement) was considered unreasonable by Aristotle. However, Aristotle is related to the development of the modern atomic theory in the following sense. While the original work of Leucippus and Democritus was lost, it came to be known through Aristotle’s criticism. The works of Aristotle, were stored and disseminated in the Islamic culture, and through it, they came back to Europe and the Christian civilization. For the scholastic period, this acceptance of Aristotle’s work became dominant, especially because it was considered to be consistent with the Bible. At the end of the 18th century it was believed that experimentation could contribute to the research of the laws of nature and structure of matter. So for example the discussions around the premise that if in a room there is burnt a very small amount of incense, the smell reaches all over the room which is much larger than the space originally occupied by the incense...». 1. Identify the role played by religious beliefs of people in the medieval times to make Aristotle’s view to prevail and Democritus’s view to be overlooked. List the factors that contributed to challenging this view. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… …………………………… 2.Express your views about what a scent is. Student’s Learning Activities (Democritus and the atoms) 3 Storytelling Teaching Model: http://science-story-telling.eu ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………… 3.Explain how burning a small amount of incense in a room can be proof that matter consists of particles. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………… Activity 3 In the above text is quoted: “…At the end of the 18th century it was believed that experimentation could contribute to the research of the laws of nature and structure of matter” please discuss in your team this view. Research in the internet to find important experiments in the history of science, which were milestones for the development of science, and write some of them. Discuss in your team about the role of experiment in the progress of science. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… 4 Student’s Learning Activities (Democritus and the atoms) Storytelling Teaching Model: http://science-story-telling.eu ……………………………………………………………………………………………………………… ………………………… Activity 4 Discuss in your group the phrase: «In the room there are small particles that are constantly moving». Suppose that you can see any particle regardless of its size, then draw and explain what these particles are and how they move. Activity 5 Based on a web research, write a text about modern scientific views concerning the structure of matter. …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………… Activity 6 According to Democritus and Leucippus: "With specific combinations of atoms new substances are created”. Is this axiom proven today or not? If your answer is yes, please indicate how these substances are called. Name five examples of such substances. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… Student’s Learning Activities (Democritus and the atoms) 5 Storytelling Teaching Model: http://science-story-telling.eu ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… …………….. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………… Student’s Learning Activities (Democritus and the atoms) were written by Aikaterini Rizaki and Panagiotis Kokkotas with the support by the European Commission (Project 518094-LLP-1-2011-1-GR-COMENIUS-CMP) and the NKUA of Greece. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained there in. Historical background atoms.pdf Background Atomsatoms 1 Storytelling Teaching Model: http://science-story-telling.eu Background atoms The concept of Atoms is fundamental to our modern scientific understanding of the world. The em- inent physicists Richard P. Feynman pointed out that “[i]f, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of crea- tures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms – little particles that move around in perpetual motion, attracting each other when they are little distance apart, but repelling upon being squeezed into one another” (Feynman et al. 1963, I- 3). This quotation is for several reasons relevant with respect to this historical background: On the one hand, Feynman is pointing out extremely clear how important the concept of an atomic struc- ture of matter is to modern science. Yet, he also raises implicitly another issue that is very relevant if the genesis of this concept is analysed: Feynman speaks in this introduction to the first lecture of the ‘atomic hypothesis (or the atomic fact, or whatever you wish to call it)’, and in doing so he ad- dresses and ignores at the same time a crucial detail: is the existence of the atom an hypothesis, or is it a fact, and if so, what really is part of this fact – which level of description can still be taken as being a fact, which are additional hypothesis. Feynman ignores this issue by leaving it to the reader how she or he wishes to call it – this appears to be a crude form of relativism that can possibly be explained by looking at the date of the publication: Feynman’s lectures date from the early 1960s, for that time it appears to be questionable whether a different position could be expected in epis- temological or in nature of science categories. Such a statement appears to be somewhat irritating from our point of view, yet, it demonstrates how far the knowledge about the nature of science has developed in recent decades. In order to teach this central concept, one aspect gets relevant which was also important in the historical development but will not be discussed in this historical background: The notion of a chemical element is a prerequisite for the formulation of the atomic model – this can be seen in the historical analysis booth for the development in the Greek antiquity as well as for the modern period, and it can also be identified in the educational conceptions. How- ever, the historical development of the concept of elements will not be discussed in this back- ground material but is assumed to already ex- ist. Ancient discussions about the structure of matter The question how the material world is structured has been discussed in particular in Greek Antiquity (a knowledge which is in part due to the transfer of knowledge from this pe- riod to the Early Modern Era in Europe).1 In this respect, the topic of a prime element that 1 There is evidence that models of the material world existed also in the Indian culture as well as in Babylonian culture, however, documentation is poorer and these concepts have not played any role in the introduction of an atomic theory into Europe- an science – thus they are not discussed in the back- ground. constitutes all the other substances becomes relevant, however, it is of course not even syn- onymous with a simplistic atomic concept as this prime element could exist without any corpuscular structure. Philosophers such as Thales of Miletus, Anaximenes, Heraclites and Empedocles were among those scholars who developed or promoted respective conceptions. About 450 BC, two philosophers developed ideas that are relevant to the introduction of the atomic conception: Democritus and Leucip- pus. Both postulated that the material world is made from very tiny particles, which them- selves cannot be any further separated into smaller parts. These atoms were distinguished from each other by their shape and size. Ac- cording to Democritus, these atoms move in the empty space and collide with each other. By specific combinations of atoms, other sub- stances are formed, yet, these combinations are not permanent but the atoms can separate again. However, the concepts of Leucippus and Democritus were not accepted by their con- temporaries: “Two factors weighed against any widespread acceptance of the classical version of atomism. The first factor was the uncom- promising materialism of this philosophy. By explaining sensation and even thought in terms of the motions of atoms, the atomists chal- lenged man’s self-understanding. Atomism seemed to leave no place for spiritual values. 2 Background Atoms Storytelling Teaching Model: http://science-story-telling.eu Surely the values of friendship, courage, and worship cannot be reduced to the concourse of atoms. Moreover, the atomists left no place in science for considerations of purpose, whether natural or divine. The second factor was the ad hoc nature of the atomists’ explanations”. (Loose 2001, 25) Additionally, there was a rival concept which appeared superior as it ex- plained the behavior of matter: the four ele- ments conception which explained all existing matter as well as its properties through four elements: Water, Air, Fire, and Earth.2 A central, if not the central figure for the re- jection of this atomic theory was Aristotle, who advocated the four elements theory and added as a fifth: ether, which filled the space between the celestial bodies. This was relevant as – ac- cording to Aristotle – no empty space could exist – the horror vacui, nature’s ‘fear’ of emp- tiness. Moreover, according to his conception, everything in nature is intentional; there is no superfluous action in nature. Additionally, each object has a natural position, and if displaced, it aims at getting back to this position. Conse- quently, Aristotle was able to explain observa- ble processes with his principles. The atomists were not only unable to propose a superior explanation, even more: they assumed the ex- istence of particles no one could see. This was a major criticism Aristotle made against the atomic theory, apart from that he did not ac- cept the idea of the empty space which was according to his own conception impossible. And a permanent motion appeared absurd in Aristotle’s understanding. All in all he opposed the atomic concept which was in contradiction to several of his central beliefs. Yet in some sense he is still relevant to the modern devel- opment of the atomic theory as the original works of Leucippus and Democritus were lost and were actually known only through his criti- cism. Aristotle’s works were kept and expanded in the Islamic culture, and through this culture, they came back to Europe and the Christian culture. For the scholastic period, this Aristote- lian understanding became dominant, particu- larly as it was considered to be coherent with 2 It has to be understood that these elements were not what we call Earth, Fire, Air, and Water, but they are elementary principles (see also the background on the development of the Periodic Table). the Bible. Yet, astronomers and slightly later natural philosophers developed a different understanding of natural processes – conse- quently the authority of Aristotle was more and more questioned throughout the 17th and 18th centuries – at the end of this period, it was the experimenting enlightened natural philosopher who was considered to be able to uncover the laws and structure of nature. In this process some experiments and considerations were developed that seemed to strengthen the an- cient atomic hypothesis. Of particular im- portance was the demonstration of the exist- ence of the vacuum.3 In another argumentation it was discussed that if a tiny bit of incense is burned, it can be smelled in the entire room. As this room is significantly bigger than the space the incense initially occupied, the initial piece has to be divided into more than 750.000.000 parts – these calculations were intended to show how small the particles have to be that form the piece of incense (see Beer & Pricha 1997). However, such a discussion remained on the level of simple calculations, there was no claim whatsoever that atoms exists or what their properties might be. Such an understand- ing was only developed in the early 19th centu- ry. Structuring matter: Dalton When looking into the genesis of modern science, probably the first scholar to establish an atomic conception is John Dalton, a chemist who was following Lavoisier’s new, quantita- tive approach towards chemistry. Using a bal- ance to analyze chemical reactions formed a major achievement of Lavoisier’s new chemical system, and this enabled chemists to take a different perspective on chemical reactions. Lavoisier himself established the difference towards classical chemistry and the novelty of his approach several times, to give but one ex- ample: “Lavoisier wrote in the Opuscules phy- siques et chimiques (1774) that he ‘applied to chemistry not only to the apparatus and meth- ods of experimental physics but also the spirit of precision and calculation which characteriz- es that science’.” (Nye 1993, 35). Yet, it was not only the methodological step or conceptual modifications that made Lavoisier’s chemistry 3 On some of the controversies with respect to the existence of a vacuum and the related philosophical implications see Shapin & Schaffer 1989. Background Atoms 3 Storytelling Teaching Model: http://science-story-telling.eu distinct to the previous understanding. A key element in his chemistry was the different no- tion of chemical reactions that helped him to use the quantitative description, and the un- derstanding that ‘simple substances’ can be interpreted as elements that cannot be decom- posed any further. In this respect, Lavoisier stated explicitly: “I shall, therefore, only add upon this subject, that if, by the term elements, we mean to express those simple and indivisi- ble atoms of which matter is composed, it is extremely probable we know nothing at all about them; but if we apply the term elements, or principles of bodies, to express our idea of the last point which analysis is capable of reaching, we must admit, as elements, all the substances into which we are able, to reduce bodies by decomposition.“(Lavoisier 1794, xxiii) Remarkably, Lavoisier is already using the term ‘atom’, even though he is not using an atomic theory. However, this notion of element that gets evident in this quotation is also rele- vant to the introduction of the atomic theory. A key understanding resulted from the quantitative observations at the end of the 18th century: most compounds are the result of the reaction of specific ratios of masses of the ele- ments that form this compound. This rule be- came known as the law of constant composi- tion. Even though this law appeared to be valid for the chemical reactions that had been ana- lyzed quantitatively, there was another striking aspect, and this was first characterized by John Dalton. Dalton realized that there were some chemical reactions in which different com- pounds were formed through a combination of the same elements (i.e. from a reaction of cop- per with oxygen two different compounds can result, likewise carbon and oxygen, and so on). The resulting compound depended on the amount of the two initial substances that react- ed with each other. However, there was also some regularity that Dalton noticed: there was a ratio of small integer numbers between the masses of element A that reacted with the same amount of element B to two different com- pounds. From this finding Dalton formulated another law. the law of multiple proportions characterizes that if two elements possibly re- act to more than one compound, then the masses of element A reacting with the same amount of B are small integer multiples. This law, together with the law of constant composi- tion, forms the starting point towards the stoi- chiometric approach in chemistry. However, even though this law was based on empiric evidence, it was not the only conclu- sion that Dalton drew from his experiments: In a lecture delivered at the Royal Institution London4, he proposed the following ideas which form the basis of the modern atomic theory of matter: “All matter is composed of atoms Atoms cannot be made or destroyed All atoms of the same element are identical Different elements have different types of atoms Chemical reactions occur when atoms are rearranged Compounds are formed from atoms of the constituent elements.”5 Evidently, Dalton’s use of the term atom is different to the one of Lavoisier. Dalton’s con- ception of the atom is characterized by their countability, they have a certain weight and so on, whilst in Lavoisier’s conception it is more their chemical property which is relevant, and it is even unclear whether this is an actual par- ticle. This assumption enabled Dalton to prepare an explanation of the stoichiometric laws he and others had formulated. According to this understanding, the law of constant composition results both from the understanding that all atoms of the same element are identical, and that chemical reactions are a result of the rear- rangement of the atoms. The law of multiple proportions can then be interpreted as being the result of different arrangements of the at- oms that result in different compounds. In do- ing so, the knowledge about quantitative chem- ical analysis became based on a first paradigm in the Kuhnian sense (and in this respect, one could argue that this achievement turned stoi- chiometric chemistry into a science in the Kuhnian sense). Yet, things were not that easy: Even though Dalton’s theory was adopted by several chemists very quickly, others rejected it. A key problem was the assumption that each element was formed by a different atom, as a result there were about thirty different atoms at the beginning of the 19th century, and their number was increasing. Thus, instead of simpli- fying the structure of matter, Dalton’s atomic 4 According to Clarke (1803), the first presentation was made at the Manchester Philosophical Society. 5 http://www.rsc.org/chemsoc/timeline/pages/1803 .html, last access April 18, 2012 4 Background Atoms Storytelling Teaching Model: http://science-story-telling.eu theory made nature more complex. Despite this criticism, the stoichiometric laws were used by chemists, and some of them used fractional numbers to express the ratio of masses – indi- cating that there was no inseparable particle. This was not just a problem of initial ac- ceptance, even sixty years later, reservations against this theory were stated very explicitly, e.g. the President of the Chemical Society Wil- liamson stated in a speech in 1869: “… that on the one hand, all chemists use the atomic theo- ry, and that, on the other hand, a considerable number of them view it with distrust, some with positive dislike.“ (quoted in Tilden & Glasstone 1926, 227). And some renown chem- ists and physicists at the beginning of the 20th century still rejected the atomic theory – we will come back later to this issue. Yet, particu- larly for chemists, the atom became an entity that was used in their analysis of chemical reac- tions. However, it was not considered to be real (neither in the positivistic sense nor in the sense of a relevant theoretical description) but just a heuristic tool which was very adequate in terms of describing chemical reactions, but had nothing to do with the actual understanding of matter (Görs 1999). The atom gets established Despite the discussions amongst the chem- ists who accepted the atom as a useful hypoth- esis, the physicists started to use the atom as a real object with explanatory power. Particular- ly the developing science of thermodynamics played an important role in the establishment of a physical atom that is crucial for the kinetic theory (atoms in motion represent heat). How- ever, this understanding was strongly criti- cized, particularly in the German speaking sci- entific community by eminent scientists such as Ernst Mach, Wilhelm Ostwald and Georg Helm.6 The controversy between these re- searchers (Ostwald was a Nobel Prize winner in 1909, Mach was also very prominent in his times) and the proponents of a statistical inter- pretation (most notably Boltzmann) was not just based on physical issues but involved also deep philosophical questions. A key aspect in 6 For other reasons, also Max Planck initially criti- cized atomism as he understood it in Boltzmann’s statistical interpretation, see Müller (2008). This discussion was not limited to the German speaking community; another example of the opponents of atomism is Poincare this respect was the question whether individ- ual atoms can be seen, or whether there is any evidence for the existence of individual atoms. Actually, at the beginning of the 20th centu- ry, it appeared that the atomic theory was con- sidered to be overthrown, and Boltzmann to be a relic from the 19th century. Things changed significantly when Planck’s theory of radiation was established and at about the same time Einstein and Smoluchowski published their interpretation of Brownian motion. This was a phenomenon described already in the 18th century by several observers. However, it was attributed to the biologist Robert Brown who noticed in the early 19th century that small pollen and dust particles that are floating on water moved in an erratic manner. The re- markable detail about this motion was that it never appeared to stop, moreover, the moving particles were certainly not alive. It remained an open question for about half a century how this motion was to be interpreted. Even though towards the end of the 19th century some re- searchers proposed solutions to this question which correspond to our interpretation, it was only in 1905/06 when Albert Einstein and Mar- ian Smoluchowski presented independently their mathematical analysis of Brownian mo- tion (actually Einstein’s paper was one of the three famous in his annum mirabilis, the other two dealt with the photoelectric effect and the special theory of relativity). Both researchers were able to explain that the motion can be caused by the motion of the particles of water due to their kinetic energy – thus, Brownian motion appeared to be a first macroscopic ef- fect that had to be explained with the assump- tion of small particles and thus forming an em- pirical evidence for the kinetic theory and thus for the atomic theory. Actually, Ostwald is said to have been convinced of the adequateness of the atomic theory through the agreement of the description and the empirical data. At about the same time, there was another empirical evi- dence for the adequateness of the atomic theo- ry, and this one is said to have convinced Mach: When radioactive particles are placed next to a fluorescent screen, minute flashes of light can be observed which are to be interpreted as results of individual α-particles. Thus, within a few years, the understanding of atomism had changed from almost complete rejection to almost complete acceptance. Boltzmann, the great proponent of the atomic theory, was at Background Atoms 5 Storytelling Teaching Model: http://science-story-telling.eu that time already dead – he committed suicide in September 1906. The atom gets a substructure Even before Einstein’s and Smoluchowski’s work helped to establish a consensus about the correctness of the atomic description of matter, some researchers established empirical results that actually contradicted the initial under- standing of the atom as being inseparable: Ac- tually Faraday’s work on electrolysis – which dated from the 1830s –could have been raised questions on the fundamental and inseparable nature of the atom as formulated by Dalton: According to Faraday’s investigation, a certain amount of electricity releases a certain amount of an element in the process of electrolysis. However, this empirical result did not raise questions with respect to the atomic nature of matter, on the contrary: It remained unclear until well into the 20th century whether elec- tricity has an atomic structure, or whether the ratio between electrical charge and released matter was the mean of several reactions that could take place at the same time. Only in the 1920’s, when Millikan’s measurements on the elementary charge were awarded with the No- bel Prize, this issue had been settled (at least for the vast majority of scientists, see Holton 1978). Yet, towards the end of the 19th centu- ry, further evidence was produced that ques- tioned the indivisible character of the atom. Actually, the starting point was research that in retrospect can be taken as being further evi- dence for the atomic theory, even though it was not interpreted in this sense in the historical situation. In the 1860’s, the chemist Bunsen showed, together with the physicist Kirchhoff, that the light emitted from a substance is very characteristic and that only special frequencies (or lines, if the spectrum is analysed) are emit- ted (or absorbed). This provided also a method to identify new elements, and the number of elements increased significantly over the next few years. Analysing spectra was a major issue, and became expanded towards analyzing also cathode rays and their interaction with gases that are filled into the tubes. In doing so, exper- imentalists had hoped to develop a further un- derstanding about the constitution of matter (Müller 2004). Particularly the analysis of cathode rays appeared to be very promising; among the researchers working in this field was J.J. Thomson. Thomson analyzed these cathode rays and established that they are formed by particles7 which have a mass of about 1/1000 of the hydrogen atom. He was also able to determine the mass-charge ratio by deflecting these particles in a magnetic field. However, what might be more relevant to this discussion are his experiments in which he used different cathode materials to emit the rays (which were basically emitted by heating up the cathode, the rays were then accelerated with an electric field). Thomson could show that all particles have similar properties, no matter from which material they were emanat- ed. This could be seen as an indication that these particles (corpuscles, as Thomson called them) were a fundamental part of matter. However, there was a problem: When these corpuscles were that lightweight, but electrical- ly charged, and they form a part of matter, then how can stability be created? Thomson finally came up with a solution: “We suppose that the atom consists of a number of corpuscles mov- ing about in a sphere of uniform positive elec- trification …” (Thomson 1904, 255).8 This meant that the (at this time still disput- ed atom) was no longer indivisible, and that the model of the atom had to be modified. Another modification became necessary soon after- wards, and this was related to another field which emerged in the very early 20th century: radioactivity - which will be discussed in the next chapter. One of the researchers who estab- lished their scientific career in analyzing this phenomenon was Ernest Rutherford, a physi- cist from New Zealand who did his early re- searches (which won him the Nobel Prize) in Canada and then moved to England again. In the Cavendish laboratory two of his assistants – Marsden and Geiger – carried out the experi- ment to scatter α-particles with metal foils (Geiger & Marsden 1909). 7 Quite remarkably, his son George Paget Thomson was also awarded the Nobel Prize in physics, this time for his work on electron diffraction. In some sense, it could be (admittedly oversimplified) ar- gued that J.J Thomson was awarded the Nobel Prize for demonstrating that electrons were particles, whilst his son was awarded the same honor for demonstrating that electrons are no particles but have also a wave character. 8 Actually the Japanese physicist Nagaoka came up with a similar solution one year earlier. 6 Background Atoms Storytelling Teaching Model: http://science-story-telling.eu Rutherford had already suspected that a scattering is possible when he observed the passage of α-particles through sheets of mica. This experiment was taken up again, and the result was more than irritating (even though not completely unexpected: Geiger and Marsden observed that even though the vast majority of α-particles passed the metal foil (and in the course of the experiment they used gold foil as this could be prepared extremely thin), with some of them being scattered, very few of them were reflected. “In retrospect, Marsden’s discovery was the ‘most incredible event’ that had ever happened to him [Rutherford, PH], almost as incredible, he would say, as if a fifteen-inch shell fired at a piece of tissue paper bounced back and hit the gunner. That the military imagery and the in- credulity are later fabrications we can see easi- ly from a lecture Rutherford delivered … six month after the discovery of the diffuse reflec- tion (Heilbron 1981, 264f.) Be this statement as it may, the result was certainly unexpected to the scientific communi- ty, and Rutherford came up with an explanation that was certainly also unexpected: He calcu- lated from the behavior of the α-particles that the atom had a small positively charged nucle- us that contains almost all the mass, whilst most of the space of the atom was empty, ex- cept for the electrons that moved around somewhere in this space. Atoms can change As already mentioned, Rutherford became famous for his researches in radioactivity – yet he was not the person to open this field. The first researcher who actually observed radioac- tivity was the French physicist Henri Becquerel – his discovery (and one can use this term as this was completely unexpected even though some sensibility for radiation effects certainly existed due to Röntgen’s demonstration of the X-rays) opened a new field. Yet, this field was not entered immediately by Becquerel himself or other scientists, but the rays emitted from Uranium salts were just considered to be a cu- riosity not worth any further scientific atten- tion. It was the collaboration of a young Polish chemist with a French physicists that actually made the importance of this new field evident: Marie and Pierre Curie could use the radiation to show that within several radioactive samples other elements than Uranium have to exist as the radiation was stronger than the one emit- ted from pure Uranium. In a long and laborious analysis, they were finally able to prepare pure samples of the elements Polonium and Radium. Particularly Radium became central to the re- search in the new field of radioactivity as it was fairly active and produced different rays. Yet, it became evident, that a lot more chemical ele- ments have the ability to emit such a radiation. However, there were several things that turned out to be really astonishing – among them cer- tainly the transformation of one element into another in the process of an α- or a β-decay. This gets evident from an anecdote that brings us back to Rutherford: “Rutherford and Soddy found, for example, that radioactive thorium, atom by atom, was gradually turning itself into radium. At the moment he realized this, Soddy … blurted out, ‘Rutherford, this is transmuta- tion!’ ‘For Mike’s sake, Soddy,’ his companion shot back, ‘don’t call it transmutation. They’ll have our heads off as alchemists” (Weart 1988, 5f.). Already the work of the Curies’ had estab- lished a fundamental idea: The radiation of a material is related to some properties of the element. Uranium has a different radiation than Polonium and Radium, and so on. Moreover, it became evident through experiments that the activity of a sample gets reduced over time – which is evident when the transformation of the atoms into those of another element is tak- en into consideration. However, there was also a problem with respect to the decrease of the activity, it became evident that the half-life was not a value that could be used for an individual atom, on the very contrary. The law of radioac- tive decay worked only for a statistical sample, a prognosis of the behavior of the individual atom was not possible. Initially, this was taken to be an indication of the required development in atomic physics, however, it became evident in the end that this is simply not possible and the decay can only be described mathematical- ly in terms of the statistic of the ensemble. Moreover, in analyzing the radiation, three different types could be identified and soon characterized. Another surprise came with the α-rays – they turned out to be helium, an ele- ment that until then was only detected in the Background Atoms 7 Storytelling Teaching Model: http://science-story-telling.eu sun (with spectroscopic methods) and seem- ingly did not exist on Earth. Yet, as the α-rays appeared to be positive particles whilst the β- rays were electrons, this meant that not only the electrons could be emitted from the atom but also some of the positive substance. Physical atoms and chemical atoms Determining the properties of the different rays was one of the first things that experi- menters did once it became evident that this was a relevant topic. Among other things, mass and charge of the particles that formed the rays were determined. This was done by applying a well defined magnetic field rectangular to the direction of the rays – from the deflection the charge/mass ratio could be determined. A comparable set-up was used to analyze atoms, and this provided another insight into their structure as well as it solved one of the remain- ing problems. Particularly through the work of Francis Aston, who modified this set-up into a mass spectrometer, it became evident that even though from a chemical point of view all atoms of an element are indistinguishable, this was not the case from the physical point of view. Aston could demonstrate that for several ele- ments different atoms existed that could be distinguished (and only be distinguished) from their mass. This helped to explain why certain elements had an atomic weight that was not an integer multiple of the mass of the hydrogen atom. From Aston’s data it became evident that the atomic weight was the weighted mean of the atoms’ mass. Looking at the masses of each kind of atoms (which were predicted and called isotopes already before by Rutherford’s collab- orator Soddy) it became evident that the atom- ic weight of each individual isotope was (within the accuracy) an integer multiple of the Hydro- gen atom. Atoms can be changed Whilst most experiments with radioactive substances aimed at analyzing the radiation, some researchers also attempted to modify atoms (artificial ‘transmutation’). Initially, α- particles were used, they were shot towards matter and it could be observed that some at- oms were able to integrate the α-particle in the nucleus, thus forming a new element. The first to establish this experiment was again Ruther- ford who could show that when α-particles are sent through Nitrogen, Hydrogen and Oxygen are traceable. Rutherford’s interpretation was that the Nitrogen nucleus was absorbing an α- particle, and the newly formed nucleus would immediately emit a hydrogen nucleus. This was the first successful attempt to modify an ele- ment and to create a new one – other such ex- periments quickly followed. Yet, it has to be understood that this is not a nuclear fission, this was still considered to be impossible. Rutherford named the Hydrogen nucleus proton, and postulated that this proton is an elementary component of all nuclei. Yet, the mass of the nuclei does not form integer multi- ples of the mass of the proton, this was still a major problem. At the same time, two more questions still existed: Why can positive pro- tons form the nucleus, and how to explain a β- decay. Rutherford assumed that also electrons exist in the nucleus and form pairs together with protons, and these pairs should keep the elementary particles in the nucleus together. Among the researchers that tried to investi- gate the nucleus and the atom through interac- tion with α-particles were Irène Joliot-Curie (daughter of Marie Curie) and her husband Frédéric. They repeated some experiments which had been carried out in Berlin: Beryllium was irradiated with α-particles; as a result a significant radiation could be observed which they initially took as γ-rays. The particles of this radiation were not charged and appeared to have an extremely high energy. Even though the particles were not charged, they could in- teract with hydrogen and release electrons. Whilst the Joliot-Curies kept their interpreta- tion of the result of their experiments being γ- radiation, James Chadwick, who was working with Rutherford, choose a different interpreta- tion. According to Chadwick this radiation was to be explained with a new corpuscle and thus the radiation was a completely new type. Fur- ther experiments showed that the particles had a rest mass similar to the proton, and could be seen as the particle that replaces the proton- electron-pair Rutherford had assumed to ex- plain the (relative) stability of the nucleus. The neutron enabled further experiments on transmutation, as it is neutral, there is not the repulsive electrostatic force that was a problem in attempting to get an α-particle into the nucleus. Several researchers worked on 8 Background Atoms Storytelling Teaching Model: http://science-story-telling.eu this field as it enabled the creation of new radi- oactive isotopes as well as new products of decay. Among those researchers were the Jo- liot-Curies in Paris, Fermi in Italy, and Hahn and Strassmann in Berlin. Both aimed at getting a neutron into the nucleus of Uranium, at that time the heaviest element to be known. The idea was to produce the so-called transuranium elements, elements with a greater atomic num- ber than Uranium. This appeared to be the only possibility to develop new elements as the Pe- riodic Table was considered to be complete. Particularly the chemist Hahn was very un- satisfied with his results: It appeared that through his experiments, Uranium had been turned into Barium – which has significantly lesser atomic weight than Uranium. Hahn ad- dressed this issue in a letter to the physicist Lise Meitner. She had been working with Hahn for a long time and recently had to flee to Swe- den from the threat of fascist Germany after the so-called Anschluss of Austria. Meitner re- sponded initially that such a result does not seem to be plausible.9 However, as she pointed out in the same letter, there had been so many surprises in the history of radioactivity that one could hardly could say, this or that is impossi- ble. Hahn insisted that he had verified Barium, and Meitner pointed out in another letter writ- ten a couple of days later that at least from the energetic point of view, a fission could have occurred. In a discussion she had with her nephew Frisch, Meitner came to the idea that possibly the model of the atom had to be thought like a drop – if an object with adequate energy hits that drop, breaks this drop into two smaller ones. Hahn finally published his findings (togeth- er with Strassmann) and pointed out that for him as a chemist, he had to state that the result- ing isotopes behave like Barium, yet he claimed that from the point of physics he was still not convinced that this element could be produced in such an experiment. This changed very quickly, and scientists immediately pointed out that in such a reaction not only a significant amount of energy would be released, but also 9 Before these experiments were carried out, how- ever, the concept of nuclear fission had already been formulated by Ida Noddack already in 1934 when she was criticizing the discussion of Fermi in his experiments on transurane elements. other neutrons, thus, a chain reaction appeared possible. Note that some audiofiles with Protagonists such as Thomson, Rutherford, Hahn etc. are to be found at http://www.aip.org/history/mod/fission/fissi on1/01.html I am indebted to D. Metz (University of Win- nipeg) for his careful proof-reading as well as for comments on the previous version of this background material. References Heidelberger, M. (1993). Die innere Seite der Natur : Gustav Theodor Fechners wissenschaftlich- philosophische Weltauffassung. Frankfurt am Main: Klostermann. Heilbron, J. L. (1981). Historical studies in the theory of atomic structure. New York: Arno Press. Holton, G. J. (1978). The scientific imagination : case stud- ies. Cambridge [Eng.]; New York: Cambridge University Press. Lavoisier, A. L. (1794). Elements of Chemistry. Transl. by Kerr, 4th ed., Edinburgh: William Creech. Losee, J. (2001). A historical introduction to the philoso- phy of science. Oxford [England]; New York: Oxford University Press. Morgenweck-Lambrinos, V., & Trömel, M. (2001). Wissen- schaft und Legende: eine Nachbetrachtung zu Lise Meitner, Otto Hahn und die Kernspaltung: eine Legende aus unseren Tagen. NTM, 9, 29--40. Müller, F. (2004). Gasentladungsforschung im 19. Jahr- hundert. Berlin: Verlag für Geschichte der Naturwissen- schaften und der Technik. Müller, I. (2008). Ein Leben für die Thermodynamik. Vom Zweiten Hauptsatz der Thermodynamik zum Planck- schen Wirkungsquantum. In: Physik Journal 7/3, 39-45. Nye, M. J. (1993). From chemical philosophy to theoretical chemistry : dynamics of matter and dynamics of disci- plines, 1800-1950. Berkeley u.a.: Univ. of California Press. Rife, P. (1992). Lise Meitner: ¬Ein Leben für die Wissen- schaft. Hildesheim: Claasen. Shapin, S., & Schaffer, S. (1989). Leviathan and the Air- Pump: Hobbes, Boyle, and the Experimental Life (1st Paperback Edition ed.). Princeton: UP. Sichau, C. (2005). Atomphysik : historische und fachliche Materialien zur Unterrichtsvorbereitung. Oldenburg: Didakt. Zentrum (diz). Background Atoms 9 Storytelling Teaching Model: http://science-story-telling.eu Simonyi, K. (1995). Kulturgeschichte der Physik: von den Anfängen bis 1990 (2. Aufl. ed.). Thun, Frankfurt/Main: Deutsch. Thomson, J.J. (1904). “On the structure of the atom: an investigation of the stability and periods of oscillation of a number of corpuscles arranged at equal intervals around the circumference of a circle; with application of the results to the theory of atomic structure”. In: Philo- sophical Magazine 6 Volume 7, Issue 39, 237-265 Tilden, W. A., & Glasstone, S. (1926). Chemical discovery and invention in the twentieth century. London: Routledge. Weart, S. R. (1988). Nuclear fear : a history of images. Cambridge, Mass.: Harvard University Press. Background atoms was edited by S. Klassen Background atoms was written by Peter Heering with the support of the European Commission (project 518094- LLP-1-2011-1-GR-COMENIUS-CMP) and the University of Flensburg, Germany. This publication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the infor- mation contained therein Historical Ressources.pdf A Primary Sources (Greek) Aristotle: De caelo, english translation 1922, online available:http://archive.org/details/decaeloleofric00arisuoft. Plato: Plato: Timaeus and Critias ; Translated Into English with Introductions and Notes on the Text, London 2013. B Primary Sources (Translations) Black, John: The Four Elements in Plato’s Timaeus, Lewiston, N.Y u.a. 2000. Bostock, David: Space, Time, Tatter, and Form: Essays on Aristotle’s Physics, Oxford, Repr. 2009. Freudenthal, Gad: Aristotle’s Theory of Material Substance: Heat and Pneuma, Form and Soul, Oxford 1999 links.pdf http://www.youtube.com/watch?v=1nXnTu6jymM& Story_Democritus_ENG.pdf Laughing Philosophy 1 Storytelling Teaching Model: http://science-story-telling.eu Laughing Philosophy Plato was walking home, it was a hot afternoon, and he just wanted to get back into the cool space of his house. He was in a rush, despite the temperature, not only because he wanted to get home, but also be- cause he was in a bad temper. Plato was annoyed, something this ridiculous had not happened to him for quite some time. He was a well-established philosopher, certainly amongst the most renowned ones in Athens, and Athens that was at that time the center of the world – at least the civilized word. As every morning, Plato had gone into the Academy, a school he had founded, to teach some of his students phi- losophy. This time, things had been different. This time, an old man had been standing around, asking whether he might benefit from Plato’s wisdom. And Plato, feeling a bit flattered by the old man’s admira- tion, had agreed. Oh, what a fool he was! Things had developed a bit unusual, as he started to discourse on the structure of the world. He was just discussing material objects, that they are all to be interpreted due to the four principles, Water, Fire, Earth, and Air, and that these four elements can be related to the regular bodies, the Icosahedron, the Tetrahedron, the Cube and the Octahedron. When he made this statement, he was interrupted by a weird sound, and he noticed that the old man was the source of the sound – he stood there, bend over and one arm in front of his face. Evidently, at least that though struck the mind of Plato, the old man was not well. He con- tinued to develop his argument, but only after a few sentences, he could not overhear the sound again, and this time, it did not only disrupt him, but also his students could not but notice. “Are you not well?” Plato asked, “shall someone fetch you a glass of water?” The old man looked up, took away the arm from his face, and this was the moment when Plato noticed that the old man was laughing. Laughing, in his lecture! This was an unprecedented incident, and Plato felt his anger rose immediately. “How dare you disturb my thoughts?” he said, or shouted, but the old man, just wiping away a tear, started to cough at first, and then said: “Oh, I am so sorry, but the devel- opment of your argument is – despite its seeming- ly logic –missing a point so evident and clear that I could not help but laugh about that. I am really sorry, I did not mean to upset you, but I just could not control myself.” The excuse – if it was intend- ed to be a real excuse – did not work to calm down Plato, on the contrary. “So, you think I have missed a point, and what could that be if I may dare to ask” Plato’s voice had become sharp and cold, and the old man seemed to get sober from that tone. “I beg your pardon, honestly, I did not mean to offend you. But when you were talking about the symmetrical bodies and their relation to the four principles, or four elements, I could not help wondering myself: If these four bodies are symmetrical, then what about a sphere? Isn’t a sphere the most perfect body, and aren’t due to this reason all the heavenly objects – Sun, Moon, Planets – objects that are spherical and that move on circles?” Plato had been struck by this weird argument, but even before he could respond, the old man had continued: “So if we agree that the ideal object is spherical, can we not assume that matter is formed by little spheres, spheres that are indivisible and shall therefore be called atomos [this is a Greek expression that would translate as indivisible particles] and that these atomos can combine in different manners that serve to form all the earthly objects.” Plato was well familiar with this kind of conception that had been devel- oped by Leucippus and had been further elaborat- ed by Leucippus’ student Democritus – Democri- tus! “Well, my dear friend” responded Plato in an extremely friendly voice, “before getting into our discourse, shouldn’t you introduce yourself to the students that are present here?” The old man laughed again: “Well, my dear Plato, apparently you have finally recognized me, so my thoughts seem to be well known to you. Maybe you should introduce me as your guest to the students that are attending your class?” Plato did not smile when he addressed his students: “This is the famous Democritus, one of the great philosophers from Thrace – I haven’t introduced you to his work as it appears to be so absurd that it should not disturb the learning mind.” To Plato’s surprise Democri- tus laughed again and said “So, my thinking is that dangerous that it may even confuse the thoughts of your students that are structured by the great Plato’s understanding of the world – what does this tell us about the structuring power of your conceptions when they are so easily perplexed?” Plato was aware that now his students expected a proper response, yet at the same time he was annoyed by the laughter of Democritus, and he was in a bad mood due to this unexpected disturb- ance, and he was smart enough to realize that at the moment, he was in a defensive position and that Democritus had advantages in the upcoming controversy. Thus, instead of responding directly, 2 Laughing Philosophy Storytelling Teaching Model: http://science-story-telling.eu he made a completely different proposal: “Well, my dear Democritus, you are of course right, the understanding of my students is so profound that even they will notice the absurdity of your thoughts. But as it is already getting hot and this meeting was not supposed to last for very much longer, I would like to invite you for tomorrow morning to present your understanding of the for- mation of matter, and then my students can judge themselves.” Democritus seemed to be somewhat surprised by this proposal, yet, as it was actually getting hot, and as the students seemed to be fine with this proposal, he had no other choice than to agree. Plato finally reached home, and when being in- side the house, with the cool air also his temper cooled down. He was thinking of what he should do the next day, and with his temper cooling down, his thoughts became more focused again. After a few minutes, a smile went over his face: He knew how he would act, and he knew that this would stop Democritus from laughing. The next morning was significantly cooler, and Plato was in a good mood when he was walking towards the Academia. His good mood was changing to the worse when he was approaching the Academia, unmistakably there was a very peculiar sound – Democritus was already there and already laughing again. When Plato arrived, he noticed that Democritus was talking to the stu- dents, and that the students seemingly were eager- ly waiting for him so that the dispute could start. Plato greeted Democritus and then started the dispute by saying: “I think we should start by learning from you yourself about your conception of how the bodies on the earth are constructed.” Democritus looked a bit puzzled: evidently, this was an opening that he did not expect. He cleared his throat and started to talk “When we look at a piece of iron like this rod, we can easily break it into two parts. When we take one of these two parts, we can half it once again, and we can repeat this procedure a couple of time. At one point, our fingers might not be able to separate the remaining bit once again, which you could easily imagine if you take a sand grain and try to divide it once again. But we may imagine that we can develop tools that might be suitable to half such a small particle again and again. If we can imagine that we can develop such a tool, we could ask our- selves whether there is a natural limit of partition, that is, whether there is a natural limit caused by the fact that there are smallest particles which constitute matter.” There was a weird noise, and it evidently came from Plato, Democritus paused and waited, but Plato was silent again, looking innocent and indicating with a gesture that Democritus should go on. “You may of course suppose that there is no limit whatsoever, but there are good reasons to believe that this is not the case. If we look at a rock, this is reduced over time into pieces of sand, but at the same time rocks are formed again – thus there seems to be some internal structure that makes it possible that similar forms are developed again and again.” Plato interrupted: “This is very interesting, but could we perhaps learn a bit more about your so-called ‘atomos’?” Democritus, being interrupted from his argu- ment hesitated, and then started once again: “Well, of course. Those smallest particles have a mass, and particles of one kind (e.g. iron particles) are indistinguishable. There are different particles, so iron particles are different from water particles or salt particles. Iron particles are solid and heavy, water particles are soft and greasy, salt particles are sharp as they bite our sense of taste, … “ There was again some noise from Plato that inter- rupted Democritus, but again, Plato just signalized that he should go on. “Atoms are freely moving around …” Democritus did not get any further, this time it was not just a noise that came from Plato, but he was just laughing “Ha, ha, ha” – somewhat to the puzzlement to his students who could not remem- ber to have him heard like that ever before. “So you think that these particles are moving around – and according to which laws should such a movement take place?” Democritus looked some- what puzzled: “There is no law as we know it, the particles obviously cannot be moving in a particu- lar direction but they move entirely irregular.” “Hahaha”, Plato responded again, “this is really an absurdity, of course all motion has to take place according to certain laws, this is evident to every- one with a sound mind. But maybe we should put this detail aside for a moment, there is another question I have: If one of your so-called atomos is moving from one place to another, then what has been at this place prior to the arrival of this ato- mos?” “What do you mean by this question?” Democritus responded. “Well if we assume that those atomos exist, and if we further assume that they are moving in an irregular manner, than the following question arises: When one of these ato- Laughing Philosophy 3 Storytelling Teaching Model: http://science-story-telling.eu ma moves to a place, let us say one of the water atomon, and at the very place there has previously been another water atomon, then does the first atomon enter the second?” “No, of course not, what an absurd question” replied Democritus . “Fine, you are beginning to see how absurd your concept is” Plato went on. “So if the moving atomon is not entering the one that occupies the space where it should go to, then what happens?” Democritus looked somewhat distressed and said: “What makes you think that there is an atomon at all?” Plato pretended to be puzzled for a second and then responded: “Well, do you really think that there is a space that is completely empty? Do you think that in water there is a space where no matter is? Do you think that in a piece of iron that is so extremely solid and hard, there are empty spaces? Hahaha, this is really an absurdity that is even bigger than the previous one.” Plato noticed that some of his students were also smiling, and he went on: “I have another question: Have you ever seen one of those atoma? Can you show us one of those atoma?” “Well, no …” Democritus could not finish his sentence, as Plato interrupted him again with his “Hahaha”, and then Plato went on:” So you want us to believe absurdities such as mo- tion that takes not place according to laws, and as space that is completely empty, and you have not even an observational evidence to make such ab- surd assumptions? Hahaha, this is ridiculous” and this time, also the students started to laugh with Plato. Democritus body language indicated that he was aware that he had lost this dispute, and Plato went on: “Well, I think my students have become aware why I was not talking to them about such obscure theories . But of course, my dear Democritus, if you want to learn some more so that your philosophy will improve, you are wel- come to stay with us and learn some proper phi- losophy”. Democritus was not laughing at this point, but just looked like an old, tired man as he waved aside and started to move away. The atomic theory that was developed by Leu- cippus and Democritus was not accepted at the time of its development, it took more than 2000 years until scholars around 1800 started to take up this model once again and to develop it further. Laughing Philosophy was edited by Panagiotis Kokkotas and it is based, in part, on Historical Background: Atoms written by Peter Heering and on Biography: Democritus written by Emilia Dobrowolska. Laughing Philosophy was written by Peter Heering with the support of the European Commission (project 518094-LLP- 1-2011-1-GR-COMENIUS-CMP) and the University of Flensburg, Germany. This publication reflects the views only of the author, and the Commission cannot be held responsi- ble for any use which may be made of the information con- tained therein.
-
File type
- application/zip
-
Referenced at
-