Physics, as a scientific discipline, is rooted in the fundamental principle that “all matter undergoes change.” Throughout history, civilizations have sought to understand the natural forces governing motion, light, gravity, and the physical world. During the Islamic Golden Age, Muslim scholars made significant contributions to physics, which later played a crucial role in the European Renaissance and the broader intellectual awakening in the West. Many of these discoveries laid the foundations for modern physics, and the theories developed by Muslim scientists remained influential for centuries.
Among the many great minds who contributed to the advancement of physics, three figures stand out: Ibn al-Haytham, Al-Biruni, and Al-Qasini. These scholars revolutionized the understanding of optics, mechanics, motion, hydrostatics, and gravitation, paving the way for later European advancements.
Ibn al-Haytham: The Father of Optics
One of the most brilliant physicists of the medieval period was Ibn al-Haytham (AD 965–1040). He is widely regarded as the father of optics, yet his expertise was not confined to this field alone. He was also a master of mathematics, philosophy, and astronomy. While earlier thinkers like Ptolemy had made preliminary observations about optics, their work remained incomplete. It was Ibn al-Haytham who provided a rigorous, scientific foundation for the field, making ground-breaking discoveries that would later become essential to physics.
One of his most revolutionary contributions was his precise definition of motion. He established that an object will continue to move indefinitely unless a force acts upon it to stop or alter its direction—a concept remarkably similar to Newton’s first law of motion. Centuries before the European scientific revolution, Ibn al-Haytham conceptualized inertia, an idea that would later be crucial to classical mechanics.
His most celebrated work, Kitab al-Manazir (The Book of Optics), transformed optics into a structured scientific discipline. The renowned historian of science A. I. Sabra translated this monumental work into English in 1989 under the title The Optics of Ibn al-Haytham. In his introduction, Sabra emphasized that after Ptolemy’s initial observations, the most profound advancements in optics were made by Ibn al-Haytham. The significance of his research was later fully realized in the 12th century when the Persian scholar Kamal al-Din al-Farisi provided detailed explanations of his findings.
By the 13th century, Kitab al-Manazir had been translated into Latin under the title Perspectiva, exerting immense influence on European scholars. Figures such as Roger Bacon in England, Witelo in Germany, and John Pecham in France based their optical theories entirely on Ibn al-Haytham’s research. By the 14th century, the book had been translated into Italian, and its impact continued to shape both physics and mathematics for centuries. Unlike Ptolemy’s earlier writings, which became obscure, Ibn al-Haytham’s work remained a cornerstone in the study of light and vision.
One of his groundbreaking discoveries in atmospheric optics was his observation that the moonlight disappears when the sun is 19 degrees below the horizon. He also conducted extensive research on how rainbows form, investigating the properties of light passing through different media.
Ibn al-Haytham also revolutionized the understanding of vision. While earlier theories suggested that the eye emits rays to perceive objects, he demonstrated that light enters the eye, similar to how a lens functions. His meticulous approach, combining medicine and physics, was far ahead of its time and became the foundation for later optical research.
Al-Biruni: The Critic of Aristotle’s Physics
A contemporary of Ibn al-Haytham, Abu Rayhan Muhammad al-Biruni (AD 973–1050) was a polymath who made extraordinary contributions to geography and astronomy, as well as physics. Although some of his works on physics have been lost over time, many of his insights are preserved in letters he wrote to another great scientist of his era, Ibn Sina (Avicenna). These correspondences contain detailed discussions on physics, revealing his critical engagement with Aristotle’s theories.
Al-Biruni was particularly skeptical of Aristotle’s explanations regarding motion and the nature of the universe. He was among the first scholars to challenge the Greek belief that the cosmos was eternal and unchanging. Instead, he approached physics from an Islamic theological perspective, arguing that the universe was a creation of God and subject to transformation.
His greatest contribution to physics was his pioneering work on the Earth’s dimensions. He was the first to provide a simple and accurate definition of the Earth’s radius, which he calculated using trigonometry. His method of measuring the circumference of the Earth was remarkably precise, considering the technological limitations of his time.
In discussing geological changes, Al-Biruni proposed a striking hypothesis: the Earth’s gravitational center shifts depending on the movement of mass on its surface. He theorized that what is now land may once have been underwater and vice versa. He noted that since these transformations predated recorded human history, it would be impossible to reach definitive conclusions about them.
His insights into gravitational attraction and planetary motion foreshadowed many principles that would later be developed in the field of geophysics.
Al-Qasini: The Forgotten Genius of Hydrostatics
Following Ibn al-Haytham and Al-Biruni, another significant figure in medieval physics was Abu’l-Fath Abd al-Rahman Al-Qasini, an 11th-century Iranian scientist. He made remarkable contributions to hydrostatics and particle physics. His work focused on the study of fluids, forces, and gravity, subjects that were largely unexplored at the time.
Al-Qasini’s most famous book, Mizan al-Hikma (The Balance of Wisdom), systematically analyzed the concepts of force, mass, weight, pressure, and gravity. He meticulously studied the views of earlier Muslim physicists and expanded upon their ideas. His research became a crucial reference for later European scientists, influencing the development of modern physics.
Recent studies suggest that Mizan al-Hikma had a significant impact on Isaac Newton’s work. The first chapter of Al-Qasini’s book, titled The Fundamental Laws of Physics and Mathematics, discusses mass, weight distribution, and air resistance—concepts that Newton later explored in his Mathematical Principles of Natural Philosophy. Both Al-Qasini and Newton viewed gravity as a force, highlighting the intellectual continuity between Islamic and European scientific traditions.
The life story of Al-Qasini is equally fascinating. He was originally a Greek slave who gained his freedom under Muslim rule. His extraordinary intellect earned him access to vast scientific resources, allowing him to study the works of earlier scholars like Al-Biruni. Eventually, he conducted his own research and made groundbreaking contributions to mechanics and hydrostatics. His book Mizan al-Hikma remains one of the most significant works ever written on these subjects.
The Lasting Influence of Muslim Physicists
The contributions of Muslim physicists during the Islamic Golden Age not only revolutionized scientific thought in their own time but also paved the way for later discoveries in Europe. Their rigorous experimental methods, critical engagement with ancient Greek theories, and innovative approaches to optics, motion, and gravity shaped the trajectory of physics for centuries.
Ibn al-Haytham’s theories on optics laid the groundwork for modern studies in light and vision. Al-Biruni’s precise calculations of Earth’s dimensions and his critique of Aristotelian physics opened new avenues in geophysics and astronomy. Al-Qasini’s research in hydrostatics and gravity anticipated many principles that would later become fundamental to classical mechanics.
Although the contributions of these scholars were often overlooked in mainstream historical narratives, their influence remains undeniable. The intellectual bridge they built between the Islamic world and Renaissance Europe demonstrates that science is a continuous and collective human endeavor. Their contributions stand as enduring evidence of the significant role Muslim scientists played in shaping modern physics.
