In this episode, we discuss Shubashree’s journey from earning a PhD in physics to building a career in science journalism. She talks about her experiences writing for The Hindu and her current role as Associate Editor at IIT Madras’ Shaastra magazine. As a national award-winning journalist, Shubashree shares insights into making scientific ideas accessible to a wider audience, the challenges she has faced in the field, and her advice for aspiring science writers. This conversation explores her career transition, the role of science communication, and the importance of clarity in sharing scientific knowledge.
The Greco-Roman era, which extended across various parts of Europe and Egypt, had a profound influence on the development of knowledge and architectural construction. During this period, there was a notable interaction between manual labor and intellectual inquiry, culminating in the emergence of mechanics as a significant domain of human knowledge. While written texts often addressed mechanics from an abstract perspective, construction activities and the use of small machines embodied their practical applications.
Take, for example, the lever: a device with direct, practical utility in a wide range of contexts. A deeper exploration of such a device reveals foundational concepts in mechanics and mechanical engineering. This established an important two-way relationship between abstract theory and practical implementation, a mode of thinking most clearly exemplified in the works of Hero of Alexandria.
Hero’s writings were closely linked to mechanics and mechanical engineering[1], and the knowledge he produced spread across Europe and the Arabic world. He was deeply influenced by Archimedes, frequently referencing his works across multiple treatises. In doing so, Hero consolidated earlier knowledge and repurposed it for a variety of mechanical applications. He is also credited with creating what is now considered one of the earliest forms of the steam engine using a simple pneumatic device[2].
He was also indirectly influenced by Aristotelian thought; traces of Aristotle’s Mechanica can be observed in Hero’s approach and conceptual framework. A central feature of Hero’s work lies in the foundational principles through which he analyzed mechanical devices. Specifically, he focused on five fundamental mechanical elements: the wheel and axle, lever, pulley, wedge, and screw. Hero sought to relate these devices to a core geometrical principle: the circle, and further connected them to the concept of balance. This integration of geometric abstraction with practical devices was at the heart of Hero’s methodology, making him one of the earliest thinkers to approach mechanics as both a physicist and an engineer.
Another significant aspect of his work is his use of models[1], which provided new insights into the operation and design of mechanical systems. During that period, understanding how large weights could be moved using relatively small forces, such as through the use of a lever, posed a conceptual and practical challenge. Addressing this challenge led to deeper investigations into balance and the principles underlying mechanical advantage.
At the center of these intellectual developments was Hero of Alexandria. His work exemplifies the dual nature of mechanics as both an intellectual pursuit and a practical tool. Hero’s influence helped shape the treatment of mechanics as a cornerstone of ancient scientific and technological achievement. In many ways, he unified physics and technology on a single conceptual platform, offering a distinctive way of understanding natural phenomena and applying that understanding toward practical ends.
2. About Hero – Hero’s Time and Place
Let us now examine the details concerning Hero of Alexandria. As with many ancient historical figures, it is quite difficult to determine the exact dates of his life[3]. However, there is a general scholarly consensus that he lived sometime between the 1st and 2nd centuries CE in the city of Alexandria, located in present-day Egypt.
During this era, Alexandria was under the rule of Greek authorities, and the period is typically characterized by Greco-Roman influence, often referred to as the Hellenistic period. Interestingly, one of the methods by which Hero’s era has been dated involves a lunar eclipse recorded in his book Dioptra. This particular eclipse occurred on March 13, 62 CE, and scholars think[3] this observation provides a useful temporal marker for situating Hero in history.
Little is known about his personal life, aside from the fact that he lived and worked at the University of Alexandria. This conclusion is largely inferred from the numerous books he authored, which correspond closely with the scientific and technological knowledge of that time. With regard to intellectual influences, it is clear from his writings that Hero received a thorough education in Greek literature available up to that period.
In particular, his works frequently reference those of Archimedes. There is also an indirect influence of Aristotelian thought, although explicit references to Aristotle are less common than those to Archimedes. It is important to note that Archimedes’ contributions had a profound influence on scientific thought for generations, and Hero of Alexandria was no exception.
What is particularly fascinating about Hero is that he not only demonstrated a deep understanding of Archimedean work but also possessed considerable knowledge of devices and simple machines available in his time[4]. Alongside these intellectual currents, Hero was also influenced by Ctesibius of Alexandria. His writings exhibit a connection to this earlier Greek scholar, and some scholars even speculate that Hero may have been a student of Ctesibius.
It is worth noting that the transmission of influence from older scholars to later ones was largely facilitated through published works. Given that the University of Alexandria was a renowned center of learning, it is unsurprising that Hero of Alexandria was familiar with the work of many earlier scholars.
3. His Books – Hero’s Published Works
From the existing literature, Hero of Alexandria is associated with fourteen texts, of which eight are directly attributed to him, while six other works are associated with him with less certainty[1]. Among these works, his books on Pneumatica, Metrica, and Mechanics have garnered significant attention. In the context of Pneumatica, the subject pertains to the pressure of air, water, and steam, and their applications for various purposes, including entertainment.
Mechanica, of course, covers simple devices and machines, and this work is primarily preserved in the Arabic language. It is generally attributed to a few scholars from a later period. There is also an interesting piece of work titled Automata, in which automatic machines of that time are discussed in the context of mechanics and the associated engineering. It is the Metrica that is associated with the calculation of volumes of various solids and certain planes and surfaces, which has drawn considerable attention and has become a well-known source of information.
Of course, Hero also worked on war machines, and this particular work is available in Greek. The lifting of weights was a major technical challenge during that era, and Hero of Alexandria naturally approached this problem from the standpoint of mechanics. Many of his works, including Pneumatica and Mechanica, contain elaborate discussions on various forms of weights and the techniques for lifting them.
This, obviously, is associated with the engineering tasks necessary for constructing the architectural works of that period. Another interesting aspect of Hero’s work is associated with geometry, especially through the work titled Geometrica. He also investigated calculations related to three-dimensional objects, which show a close connection to measurement principles relevant not only to devices but also to surveying landscapes and measuring distances, including those associated with human constructions such as tunnels.
There are a few works associated with definitions of mathematical entities, and their attribution remains debated. Nevertheless, all this evidence indicates a prolific intellectual life of Hero of Alexandria, and many scholars attribute this productive authorship to his position as a teacher at the University of Alexandria. For example, if one examines certain works such as Pneumatica, the instructional style in such books appears to resemble manuals for students to gain an overview of devices.
Also, the discussions are not very terse, and many scholars interpret this as a recap for students who are advancing their knowledge in mechanics and related problems. It is noteworthy that the entire body of work suggests that Hero of Alexandria not only had a strong command over mechanical machines but also possessed the ability to think in abstract terms. This is evident from his writings related to mathematics.
Such a combination of application and abstraction is one of the most significant features of Hero of Alexandria.
4. Pneumatica
Now let us look at some specific works of Hero of Alexandria, beginning with Pneumatica. The word pneuma means “wind” in Greek. The adjective essentially refers to something that contains or operates using air or gas under certain pressure. In this context, Hero’s Pneumatica describes various aspects related to the utility of air and gases for mechanical motion.
Figure 1 Drawing of an Aeolipile
The theme of this work is fascinating because it is not an abstract or purely theoretical exposition on mechanics or mechanical engineering. Rather, it is directly connected to small devices used for a variety of purposes, including entertainment. Among these are descriptions of several toys, such as birds that sing, coin-operated machines, and what is probably the first vending machine recorded in literature[2].
Among the many devices discussed, the one that has particularly captured the attention of historians of science is a device called the aeolipile[2], [5]. This is considered a prototype of the earliest steam engine. It operates using steam generated by boiling water in a kettle. The kettle is connected to a sphere with two nozzles. When the water boils, the steam enters the sphere and causes it to rotate.
The key aspect of this design is that the sphere is connected to a horizontally placed shaft. As the steam exits the nozzles, it causes the sphere to spin, thereby converting thermal energy into mechanical motion. This device has drawn the interest of many historians studying the origins of steam engines, as it represents one of the earliest known examples of thermal-to-mechanical energy conversion[2], [5].
The book itself contains fascinating descriptions of miniature devices adapted for various uses, including magic shows and theatre productions. Unlike some of Hero’s other writings, Pneumatica reads more like a manual for operating small devices, with concise and practical descriptions rather than theoretical elaboration. The quality of the diagrams in this work is particularly notable and has attracted considerable attention from historians.
One of the best-known surviving translations[6] of this work is by the Englishman Bennet Woodcroft, published in 1851 (Figure 2). This translation has become a standard reference for scholars seeking to understand the nature of Hero’s contributions. It highlights Hero’s practical orientation, which is quite distinctive among scholars of his stature.
Figure 2. An English translation of Hero’s book on Pneumatics
In comparison, the works of Archimedes and his immediate followers are generally more rigorous and focused on mathematical applications. Most of them do not discuss simple or seemingly trivial devices in the manner that Hero does in Pneumatica. Nevertheless, it is important to emphasize that Hero was deeply influenced by Archimedes. Many of the devices described in this book are based on principles associated with Archimedes and his pioneering work.
This is characteristic of Greek scholars, who regarded Archimedes as one of the earliest scientists to understand the natural world through systematic mathematics and physical models. In some of Hero’s other works, one sees this intellectual lineage in action, combining abstract analysis with practical application. This synthesis of theoretical and applied thinking positions Hero as a pioneer in engineering mechanics. Many of the devices he designed continue to be of great interest to both engineers and artists.
In this light, Pneumatica offers a compelling insight into Hero’s intellectual curiosity and his pedagogical intent, particularly in presenting devices to students through detailed and accessible instruction manuals.
5. Mechanica
Next, let us consider an overview of Hero’s book titled Mechanica. This work comprises three volumes, and the surviving text is available only in an Arabic translation. Some scholars believe that the content may have undergone certain alterations during the process of translation and transmission.
One of the earliest references to Mechanica dates to around 300 CE, made by Pappus of Alexandria, in a discussion on heavy weights and the methods used to lift them. The book is strongly grounded in principles originally proposed by Archimedes. It presents several mechanical principles with a degree of abstraction.
The concept of the balance, its theoretical foundations, and its relationship to various mechanical devices, such as pulleys, screws, and the wheel and axle, are discussed in considerable detail. A distinctive feature of this book is its treatment of the transportation of heavy objects using mechanical aids, as well as the application of the concept of the center of gravity to various solid forms and shapes.
The text includes a significant degree of abstraction and presents a theory of motion that provides insights into Hero’s understanding of mechanics and mechanical engineering. In this work, Hero refers to Archimedes as many as ten times, indicating a deep intellectual debt. Moreover, scholars have observed that Hero’s approach is indirectly influenced by Aristotelian perspectives on mechanical motion.
A notable aspect of the book is its emphasis on connecting abstract mechanical principles with practical applications. Devices such as the lever, pulley, wheel and axle, and various forms of screws are examined in depth. In this respect, Mechanica can be seen as an early treatise in engineering physics, serving as a key reference for understanding ancient mechanics and mechanical engineering.
The book’s content also reflects the context of the Hellenistic period, which was marked by elaborate construction projects. The principles and techniques discussed in Mechanica have potential relevance to these large-scale engineering efforts.
Finally, Mechanica exhibits strong intellectual continuity with Hero’s other works and shares conceptual commonalities with a few additional sources. This cohesion underscores Hero’s broader contribution to the understanding and development of mechanics in antiquity.
6. Other Works
Let us now consider a few other works of Hero of Alexandria. First among them is Metrica, a collection of three books and arguably the most well-known of his works. This text is primarily concerned with measurement and geometry and includes an elaborate discussion of what is now known as Hero’s formula—a well-known result in elementary geometry for calculating the area of a triangle given the lengths of its sides[7].
Metrica also explores the computation of square roots using iterative methods, a topic with significant applications in basic mathematics. The work focuses on the ability to perform measurements, including the calculation of volumes of solids such as Platonic solids and other fundamental geometric shapes. Ratios form another important aspect of the discussion, with solids considered in terms of divisions by arbitrary ratios, providing a geometric perspective on their structure.
The next important work is Dioptra, which deals with the measurement of length. It includes a discussion of the instrument known as the dioptra[8], which is directly related to surveying instruments that continue to be used in modified forms even today.
An interesting section of this work also discusses the odometer, a device used to measure the distance traveled by a moving object. This provides one of the earliest known references to such a device and highlights Hero’s interest in practical instrumentation.
Another fascinating work is Automata, in which Hero discusses automatic machines in great detail. This text is associated with the domains of magic, theatre, and mechanical marvels that were designed to captivate observers. There is extensive discussion on automatic doors and related architectural mechanisms, which were likely employed in temples or public spaces during Hero’s time. The work also includes ingenious systems for pouring and transporting liquids automatically, illustrating Hero’s advanced understanding of fluid mechanics and automation.
Taken together, these works reflect the rich intellectual repertoire of Hero of Alexandria. At the core of all his writings is a deep engagement with mechanics, approached both abstractly and practically. In this light, Hero’s contributions are of immense significance, offering valuable insights into the interplay between theory and application in ancient science and engineering.
7. Conclusion
Hero of Alexandria, embodied ancient human thought process that mixed physics and technology for intellectual and practical purposes. In a way, he laid the foundation to harness mechanics for practical applications and built on ideas proposed and utilised by great thinkers such as Archimedes and his followers. It is quite remarkable that a person of that era could come up with such interesting innovations for not only practical applications, but also for teaching and demonstrations for the public. Credit should also be given to the followers and students of Hero, who took his work forward and spread it across the world. Perhaps that is the best way to leave a legacy, by learning, creating and sharing knowledge.
REFERENCES:
[1] M. J. Schiefsky, “Theory and Practice in Heron’S Mechanics,” in Mechanics and Natural Philosophy Before the Scientific Revolution, W. R. Laird and S. Roux, Eds., Dordrecht: Springer Netherlands, 2008, pp. 15–49. doi: 10.1007/978-1-4020-5967-4_1.
[3] R. Masia, “On dating Hero of Alexandria,” Arch. Hist. Exact Sci., vol. 69, no. 3, pp. 231–255, 2015.
[4] A. G. (Aage G. Drachmann, The mechanical technology of Greek and Roman antiquity, a study of the literary sources. Copenhagen, Munksgaard; Madison, University of Wisconsin Press, 1963. Accessed: Jun. 11, 2025. [Online]. Available: http://archive.org/details/mechanicaltechno0000unse
[5] P. D. Bardis, “Hero, the Da Vinci of Alexandria: His Aeolosphaera and Other Inventions,” Sch. Sci. Math., vol. 65, no. 6, pp. 535–542, 1965, doi: 10.1111/j.1949-8594.1965.tb13497.x.
[6] H. (of Alexandria.), The Pneumatics of Hero of Alexandria: From the Original Greek. Charles Whittingham, 1851.
Cover of ‘Absorption and Scattering of Light by Small Particles’ by Craig F. Bohren and Donald R. Huffman.
It is important to read good books. Astrophysics, quantum mechanics, and gravity (including attempts to combine them with quantum mechanics) have been at the forefront in terms of popular physics imagination. These are wonderful subtopics of physics, but there are a few others that need equal emphasis. So, here is my attempt to fill this gap with some book recommendations.
The first one in the optics community is just called ‘Bohren and Huffman’ and is one of the best technical books I have read and continue to read. It is humorous and filled with wonderful insights that still engage researchers and students alike.
Craig Bohren, a theoretical physicist, is a wonderful writer, and you will see more of his books discussed here.
The book introduces the scattering matrix from a ‘light scattering’ viewpoint, and has a direct connection to laboratory measurements.
Humour is one of the key aspects of this book (as with others from Bohren), and the title of chapter 8 gives a nice glimpse: “A Potpourri of Particles”
There is a famous section in Chapter 11 with the heading – “Extinction = Absorption + Scattering” that wonderfully explains the physics behind it.
Overall, an outstanding book for understanding optics from an electromagnetics viewpoint and also to learn how electromagnetism is harnessed to understand interactions at the classical spatio-temporal scales.
Read this if you are interested in physics…It is a delight!
Even today, as a professor of physics, and importantly as a student of physics, I go back to his lecture series to learn AND derive inspiration from his thinking. He made physics more humane.
Many people across the globe have fallen in love with physics because of his books and the ‘way he did physics’
Feynman was a physics genius, but he had his flaws. It is important for us to note the limitations of human beings; celebrate what is good, and be aware and critical of what is not.
Duff’s famous physics textbook from 1900 (5th edition) owned by Yukawa
Yukawa’s name on the book
Hideki Yukawa’s picture on the Nobel website
Apart from sipping the wonderful Japanese coffee and exploring the streets of Kyoto on foot, I have been looking into the archives of Kyoto University. I am mainly searching for records and books related to their physics department, and obviously, one of the names that pops out very often is Hideki Yukawa.
Yukawa was one of the Nobel laureates from this university. He obtained his Nobel Prize in Physics in 1949 for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces. He is a big name in physics, and there is a physical potential named after him, which means one can understand the intellectual heft he carries as a physicist. Yukawa spent most of his scientific career at Kyoto, specifically at the Kyoto Imperial University (now, no more imperial :-) ), and is regarded as one of the inspirations for a battery of many excellent theoretical physicists to have emerged out of not only Kyoto but also Japan, and perhaps many parts of the world. While looking through the archival records, I came across one of the textbooks owned by Yukawa, which has his signature on it. It made my day !
The textbook titled “A Text-Book of Physics,” edited by A. Wilmer Duff, is a classic. Yukawa had the 5th edition (1921), and this book went on to have 3 more editions. I hope to write more about this particular textbook because the author, Wilmer Duff, had a connection to Madras University (as a Professor) in India and was also on the faculty of my post-doc alma mater – Purdue University !
The scientific world is a small place with unanticipated, wonderful connections :-)
K. Sridhar is a theoretical physicist and author currently at Azim Premji University, Bengaluru. Formerly at TIFR Mumbai, his research spans high-energy physics, including extra dimensions and supersymmetry. Sridhar also engages deeply with philosophy, literature, and education. He is the author of Particle Physics of Brane Worlds and Extra Dimensions (Cambridge University Press) and co-editor of Breaking the Silo: Integrated Science Education in India. In this conversation, we discuss his intellectual pursuits, including his recent novel Ajita.
In the previous essay, we discussed engineering civilizations. Specifically, we discussed how philosophy and technology have played a critical role in the betterment of civilization. In addition, the fact that thoughts and tools have direct implications on how human beings live cannot be overstated.
Over the centuries, there have been many people who have played a critical role in advancing philosophical thoughts and engineering tools that have directly or indirectly influenced the development of physics. Before we really get into the specifics of the science of mechanics and its historical developments, we need to investigate some of the ideas that were part of the discussion in ancient civilizations. Given that mechanical tools date back to the prehistoric era, it is not surprising that human beings took an interest in understanding how the world works within their proximity.
In such a development, a human being is always curious to understand and harness nature. To do this effectively, one will have to systematically think about how nature works. According to the existing literature from a history of science viewpoint, the Greek philosophers occupy a very special position.
Part of the reason is that their thoughts were recorded in some form or another, and these thoughts date back to a period as early as 300 to 400 BCE or even before. This also coincides with the time at which writing became an important tool to propagate ideas, and therefore, one can see the emergence of historical evidence from this era. The Greek philosophers have a great reputation in Western philosophy and have influenced the development of scientific thinking for a very long period.
This does not mean that people from other civilizations did not think about tools and philosophical ideas. Just that the availability of written records, either direct or indirect, has been one of the hallmarks of Greek civilization. Thanks to the accumulation of these texts, either in the primary or in the secondary source form, it has played a critical role in identifying a specific point in Western civilization(1).
Physics, as we know it in the 21st century, has a very different avatar compared to its origin. Among the many Greek philosophers who seriously thought about natural philosophy was Aristotle(2). Aristotle has had a long legacy of being the student of some great thinkers from the Hellenistic era.
Aristotle was a student of Plato, and Plato was a student of Socrates. So, these three gentlemen have contributed to Western philosophy in such a great way that one cannot discuss anything about philosophical discourse without bringing them into the picture. The origins of physics, too, have some connection to these gentlemen, specifically to Aristotle(3), who was guided by some processes of thinking developed by Socrates and his direct guru, Plato.
The Plato school of thinking deeply influenced Aristotle, and yet he paved his own way in Western philosophy. He was also one of the first writers among these philosophers to seriously think about natural philosophy in the form and shape that resembles the current day science. His questions were related to natural phenomena, and it is by studying them that we realize Aristotle’s contribution. As I always keep saying, it is not just the answers that make great thoughts; it is also the questions that elevate the answers and make them profound. In that way, Aristotle’s questions were profound.
Therefore, I need to emphasize the quality of the questions that Aristotle asked instead of just emphasizing the answers he gave in the process of this questioning. It also indicates that current-day physics, as we now know it is not in the form Aristotle thought about, but we can see a glimpse of some interesting ideas in Aristotle, which turned out to be extremely important. It became so critical that for the next thousand years from the time of Aristotle, the Western philosophy and the science that emerged out of it kept Aristotle as an important benchmark and developed its thought either in agreement or in rejection of Aristotle’s idea.
So much so that this thinking process in reference to Aristotle’s idea not only influenced Western civilization but also had a very deep implication for Islamic civilizations. Although Aristotle’s ideas became critical in ancient Europe and the ancient Islamic world, its ideas and categorizations of knowledge found relevance across various civilizations.
So, let’s try to get a glimpse of the man himself – Aristotle. Let us look at the biographical details of this remarkable individual and learn about his work.
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The Life of Aristotle
Aristotle was born in Stagira, Macedonia, which is in the northern part of Greece, in 384 BCE. His father was a physician to one of the kings in Macedon, and Aristotle was probably influenced by his father’s way of thinking about nature and natural phenomena. Of course, this is all conjecture because nobody knows the exact nature of the interaction between Aristotle and his father. However, this reconstruction is generally accepted based on historical texts(4).
When Aristotle was around 17 years old, in 367 BCE, he was sent to Athens to join the remarkable institution known as Plato’s Academy. During that period, Plato’s Academy was one of the leading intellectual centers in Europe, playing a critical role in shaping the thinking of various philosophers, including Aristotle.
It was at this place that Aristotle honed his skills in philosophical argumentation and the observation of nature and natural phenomena. This foundation played a crucial role in shaping his later works. For approximately 20 years, Aristotle remained at Plato’s Academy.
After Plato died in 348 BCE, Aristotle moved elsewhere. Historical texts suggest two possible reasons for his departure. One possibility is that he had intellectual differences with Plato’s nephew, who took over the Academy. The second possible reason is that the political atmosphere in Athens had become increasingly hostile toward people from Macedonia. These reasons, of course, remain speculative, although they are mentioned in historical literature.
In 343 BCE, King Philip II of Macedon invited Aristotle to tutor his son, Alexander. This is the same Alexander whom history remembers as Alexander the Great, though we will refer to him simply as Alexander. Aristotle played a crucial role in educating Alexander for more than five to seven years, deeply influencing the future conqueror’s thought process.
After about seven to eight years, Aristotle returned to Athens and established the Lyceum, a school of philosophy that had a profound impact on Western thought. This school had a unique feature—philosophers often lectured while taking long walks. As a result, the school came to be known as the Peripatetic School, recognized for its tradition of philosophical discourse while on the move.
During this period, around 330 BCE, Aristotle produced some of his most significant works, particularly in the context of physics. Even before leaving Athens, he had made substantial contributions to topics related to biology. However, in this second phase of his career, his focus broadened to natural philosophy, logic, ethics, aesthetics, rhetoric, and even music. This vast intellectual repertoire is one of Aristotle’s most remarkable features(4).
Around 323 BCE, Aristotle left Athens again following the untimely death of Alexander. During that period, anti-Macedonian sentiment was widespread in Athens, which likely motivated his departure. Within a year of leaving, around 322 BCE, Aristotle passed away at the age of 62. The probable cause of his death appears to have been natural.
All this information, of course, is based on historical sources that have been passed down through the centuries(4). One should always be cautious when interpreting ancient texts, as most of these sources survive only in translation rather than their original form. There is always a possibility of inaccuracies, and one must approach these accounts with care.
Aristotle’s intellectual journey covered a vast spectrum of human inquiry, from the heavens, as in astronomy, to logic within the framework of mathematics and, of course, physics. His interests also overlapped with observational phenomena and the life around him, which is evident from the questions he explored. Among his many areas of interest, we will focus primarily on Aristotle and his contributions to physics.
Aristotle’s writings on natural philosophy cover a vast range of topics, from celestial bodies to the nature of matter and motion. His works, though sometimes speculative by modern standards, laid the foundation for centuries of philosophical and scientific thought(5). Much of what we know about Aristotle comes from the preserved writings of later scholars, as very few primary sources from Aristotle himself remain.
Before I discuss Aristotle’s book, a few words on the origin of the word Physics. The word physics is derived from a Greek word called phusikḗ, which means natural science. This word has its origin in another word, and it is called phúsis, which means nature in Greek. The modern definition of physics is essentially derived from the Latin word physikā, which essentially means the study of nature.
This word was adapted by the old French, which was further adapted by English to be transformed into the word physics, as in natural philosophy.
In the context of Aristotle, it is the Greek word phúsis, meaning nature, is central to this discussion.
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The Eight Books of Physics
Aristotle’s Physics is divided into eight books(6), each exploring different aspects of nature and motion. Specifically, he was interested in the principles and causes of change and motion of objects. Let me give you an overview of his books.
Book One introduces Aristotle’s fundamental concepts of matter and form. A key discussion in this book is the doctrine of the four causes: the material cause, which explains what something is made of; the formal cause, which defines its shape or essence; the efficient cause, which refers to the force or agent that brings about change; and the final cause, which represents the purpose or end goal of an object or process. These causes provide a framework for understanding physical interactions and transformations.
In Book Two, Aristotle argues for teleology—the idea that nature has inherent purposes. He defends the study of nature as a legitimate form of scientific inquiry and lays out a methodological foundation for observing and interpreting natural phenomena.
Book Three explores the nature of change. Aristotle distinguishes between actuality, the realized state of an object brought about by an external force, and potentiality, the inherent capability of an object to become something else. This distinction is significant in understanding motion and transformation.
In Book Four, Aristotle explores the nature of voids, rejecting the concept of a vacuum. He also presents an interesting perspective on time, defining it as a measure of change.
Book Five classifies different kinds of motion, an important step in distinguishing natural movement from forced motion.
In Book Six, Aristotle discusses the nature of continuity and the concept of infinity. He argues against the existence of actual infinity, emphasizing the finiteness of physical reality.
Book Seven introduces the concept of the Prime Mover—an external force that initiates movement. This idea becomes central to Aristotle’s broader cosmology.
Book Eight expands on the idea of the Prime Mover as the ultimate cause of cosmic motion. This notion of an external force influencing the universe had a lasting impact on Western thought, intertwining scientific and theological perspectives for centuries.
Related to these books was Aristotle’s book titled On the Heavens. In there, Aristotle discussed his celestial theories. This four-part work, On the Heavens, explores the nature of celestial bodies and their motion.
He proposes that heavenly bodies are made of ether, a perfect and unchanging substance.
Aristotle also argues that the Earth is spherical and that celestial objects move in circular orbits—a belief that persisted until Kepler’s elliptical model. He discusses why celestial objects move in circular paths, distinguishing their motion from that of objects on Earth.
Expanding on his theory of the five fundamental elements—earth, water, air, fire, and ether—Aristotle’s ideas parallel similar concepts in other ancient civilizations, such as those in India and Mesopotamia.
Aristotle also studied natural phenomena through observations, and a related 4 book series was titledMeteorology. These books addressed:
Weather phenomena (clouds, wind, rain, lightning)
Natural bodies (lakes, rivers, seas, and geological formations)
Dynamic processes such as volcanoes and the transformation of matter
Another interesting book that Aristotle wrote about was based on his views on matter. The title of the work is unconventional and reads: On Generation and Corruption. This work, consisting of two books, discusses:
The four elements and their combinations in forming matter
The processes of transformation, mixing, and decomposition of substances
One may wonder how we know so much about Aristotle, even though he lived around 350 BCE. This is one of the remarkable features of human beings. They carry forward ideas from one generation to another.
Of course, this transmission across ages may cause errors in translation, but at least we get a gist of the idea through percolation. The records that we obtain through transmission will depend on the preservation of the sources of ideas. This is where the written text becomes so important because a physical text can be preserved, transported and reproduced with relative ease compared to oral records from the past.
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Most of the information about Aristotle comes from Corpus Aristotelisium(4). This is a multinational project about preserving Aristotle’s work. Around 200 texts are associated with Aristotle, out of which 31 have survived as the ancient textual evidence. These texts are from later eras across different countries, but one can make a connection to the original source through educated guesses and cross-connections.
So, I hope you have got a glimpse of and range of topics Aristotle was interested in from a physics viewpoint. Aristotle’s broad approach to physics covered motion, change, matter, and the cosmos. While many of his explanations were later refuted, his method of questioning and systematic exploration laid the groundwork for future scientific inquiry(5). His emphasis on philosophical reasoning remains an essential part of the intellectual history of physics.
In this essay, we discussed the origins of physics from Aristotle’s philosophical viewpoint. We learnt about his life and remarkable scholarly output. Going forward, we will explore other ideas and thinkers from the ancient age whose work you will generally find in physics textbooks. Can you guess what ideas they are and whom I am referring to? Think about it for a while…
References:
1. Adamson P. Classical Philosophy: A history of philosophy without any gaps, Volume 1. Oxford, New York: Oxford University Press; 2014. 368 p. (A History of Philosophy).
2. Shields C. Aristotle. In: Zalta EN, Nodelman U, editors. The Stanford Encyclopedia of Philosophy [Internet]. Winter 2023. Metaphysics Research Lab, Stanford University; 2023 [cited 2025 Mar 27]. Available from: https://plato.stanford.edu/archives/win2023/entries/aristotle/
3. Bodnar I. Aristotle’s Natural Philosophy. In: Zalta EN, Nodelman U, editors. The Stanford Encyclopedia of Philosophy [Internet]. Spring 2025. Metaphysics Research Lab, Stanford University; 2025 [cited 2025 Mar 27]. Available from: https://plato.stanford.edu/archives/spr2025/entries/aristotle-natphil/
4. Winzenrieth J. The Textual Transmission of the Aristotelian Corpus. In: Zalta EN, Nodelman U, editors. The Stanford Encyclopedia of Philosophy [Internet]. Spring 2025. Metaphysics Research Lab, Stanford University; 2025 [cited 2025 Apr 2]. Available from: https://plato.stanford.edu/archives/spr2025/entries/aristotle-text/
Pratidhvani (ಪ್ರತಿಧ್ವನಿ/प्रतिध्वनि) means reflection or resonance (of sound). Here, the aim of the podcast is to resonate with knowledge & humanize science. The podcast has two themes: 1) History & Philosophy of Physical Sciences & Technology, 2) Conversations with people related to their intellectual journey & themes mentioned in 1) Below is the link to all the episodes. Italicized ones are solo episodes
VISMAYA - History & Philosophy of Physics 