Share |

Abu Rayhan Biruni


Abū Rayḥān Muḥammad ibn Aḥmad Bīrūnī, often known as Alberonius in Latin, but also Al Beruni, Al Bayrooni or variants, (born 5 September 973 in Kath, Khwarezm (now in Uzbekistan, historically a part of Greater Iran), died 13 December 1048 in Ghazni (now in Afghanistan)) was a Persian Muslim scholar and polymath of the 11th century.

Biruni was a polymath with an interest in various practical and scholarly fields that relate to what nowadays is described as physics, anthropology, comparative sociology, astronomy, astrology, chemistry, history, geography, mathematics, medicine, psychology, philosophy, and theology. He was the first Muslim scholar to study India and the Brahminical tradition, and has been described as the founder of Indology, and "the first anthropologist". He was one of the first exponents of an experimental method of investigation, introducing this method into mechanics and what is nowadays called mineralogy, psychology,  and astronomy.

Biruni has for example been described as "one of the very greatest scientists of [the Islamic world], and, all considered, one of the greatest of all times” or as "one of the great scientific minds in all history”.  The crater Al-Biruni on the Moon is named after him. Tashkent Technical University (formerly Tashkent Polytechnic Institute) is also named after Abu Rayhan al-Biruni and a university founded by Ahmad Shah Massoud in Kapisa is named after him.  He was born in Khwarazm, then part of the Samanid Empire (modern Khiva, Uzbekistan). He studied mathematics and astronomy under Abu Nasr Mansur.

He was a colleague of the fellow philosopher and physician Abū Alī ibn Sīnā (Avicenna), the historian, philosopher and ethicist Ibn Miskawayh, in a university and science center established by prince Abu al-Abbas Ma'mun Khawarazmshah. He also travelled to South Asia or Central Asia (modern day Afghanistan) with Mahmud of Ghazni (whose son and successor Masud was, however, his major patron), and accompanied him on his campaigns in India (in 1030), learning Indian languages, and studying the religion and philosophy of its people. There, he also wrote his Ta'rikh al-Hind ("Chronicles of India"). Biruni wrote his books in Arabic and Persian, and spoke Khwarezmian as his first language, though he knew no less than four other languages: Greek, Sanskrit, Syriac, and possibly Berber. He is buried in Ghazni city, Afghanistan.

As a product of the medieval Middle East, Al-Biruni’s beginnings were not atypical from that of his surroundings. Born in 362/973 (AH/CE), recovered records from Al-Biruni’s own hand describes his origins as Tajik, or Iranian, although he was culturally and linguistically Persian.  Al-Biruni was born in Birun, a suburb of the city of Kath, within the Khwariz region, present day Karakalpakistan. While Al-Biruni’s early life is largely a mystery, the extension of “Al-Biruni” onto his birth name of Abu L-Rayhan Muhammad B. Ahmad has given scholars a significant start to discovering more exact locations and experiences Al-Biruni may have had.  The name “Al-Biruni” is thought to refer to Birun, his place of birth. Today, little is known about Al-Biruni’s childhood and family despite his lasting impression on academia. With minute known details of Al-Biruni’s family, it is currently understood that he came from an “average” family of Tajik origin, he was not a part of an affluent or well-known lineage. Recovered personal records of Al-Biruni have been beneficial in creating an increasingly clearer image of what his life must have been like. Al-Biruni spent his first twenty-five years in his homeland along the south banks of the Aral Sea, studying under teachers whose knowledge had great influence on his intelligence and interests.  No evidence of marriage or children have been found in Al-Biruni’s records. Al-Biruni was a man seemingly devoted to academia.

As mentioned before, Al-Biruni is quite an enigmatic figure, at least throughout his early years. Considering the time period and region Al-Biruni lived, it can be assumed that he received a maktab and madrasah education, traditional primary and secondary schooling of the Islamic Middle East at that time.  From Al-Biruni’s personal records, specific names of teachers and mentors have been mentioned as well as his pupils and predecessors. Despite a lack of specific information regarding Al-Biruni’s schooling, one character trait that is consistent throughout his education and adult life was as “an indefatigable seeker of knowledge with no love for sensuous pursuits.”  This description explains Al-Biruni’s absence of family, for he was completely enamored with his studies, perhaps on the margins of society as many anthropologists claim to be. Al-Biruni’s earliest academic interests were in the physical, natural, and biological sciences, consequently resulting in a fascination with Indian science. Khwariz, Al-Biruni’s homeland, served coincidentally as a centre for mathematical studies, which added yet another interest to his repertoire.  Later in his education, Al-Biruni did a great deal of traveling, traditionally regarded as a part of one’s education in Islam. At this point, Al-Biruni chose to travel to western India to study Indian science. While Al-Biruni’s analytical brain contributed to accomplishments in mathematics and the sciences, he was also blessed with a creative brain in which religion, culture, language and history were to become his next focal points. Further study in Djurdian, located southeast of the Caspian Sea, and Rayy, near present day Tehran, served as Al-Biruni’s next semi-permanent residences around 338/998 CE. Al-Biruni’s initial time in Rayy was peppered with academic disputes and criticism of his work and theories. With time and slight upward social mobility, Al-Biruni gained acceptance by the scholars of Rayy. With time and effort, Al-Biruni advanced from a criticized theorist to a respected academic within the span of his career.

Following an initial period of education through travel and interaction with various mentors, Al-Biruni returned to his homeland of Khwariz before 399/1008 CE.  Upon his return, Al-Biruni was recognized by the country’s prince, Abu ‘l-Hasan ‘Ali b Ma’mun and served as a political and academic teacher to the prince’s brother, Khwarizmshah Abu ‘l-Abbas Ma’mun b Ma’mun for seven years.  Al-Biruni’s work was cut short, however, when the royal employer, Khwarizmshah, was assassinated in 407/1016 C.E. upon the country’s conquest by “the powerful Ghaznawid sultan Mahmud b Subuktakin.”  Following this conquest over Al-Biruni’s home country, militia and academic minds were simultaneously taken as prisoner to Ghazna, Afghanistan. Throughout his captivity in Ghazna, Al-Biruni was curiously able to continue research and write academic works, both independently and as an accompaniment to fellow scholars as an honorable prisoner. Part of his independent work as a prisoner was spent traveling with the Ghazna military to Northwest India to teach Greek sciences.  These trips to India further sparked Al-Biruni’s interest in the country and began a study that resulted in his famous book, al-Hind or India, an unofficial ethnography.

Biruni's works number 146 in total. These include 35 books on astronomy, 4 on astrolabes, 23 on astrology, 5 on chronology, 2 on time measurement, 9 on geography, 10 on geodesy and mapping theory, 15 on mathematics (8 on arithmetic, 5 on geometry, 2 on trigonometry), 2 on mechanics, 2 on medicine and pharmacology, 1 on meteorology, 2 on mineralogy and gems, 4 on history, 2 on India, 3 on religion and philosophy, 16 literary works, 2 books on magic, and 9 unclassified books. Among these works, only 22 have survived, and only 13 of these works have been published.  6 of his surviving works are on astronomy.

Scientific method

In early Islamic philosophy, Biruni discussed the philosophy of science and introduced an early scientific method in nearly every field of inquiry he studied. For example, in his treatise on mineralogy, Kitab al-Jawahir (Book of Precious Stones), he is "the most exact of experimental scientists", while in the introduction to his study of India, he declares that "to execute our project, it has not been possible to follow the geometric method" and develops comparative sociology as a scientific method in the field. He was also responsible for introducing the experimental method into mechanics, the first to conduct elaborate experiments related to astronomical phenomena, and a pioneer of experimental psychology.  Unlike his contemporary Avicenna's scientific method where "general and universal questions came first and led to experimental work", Biruni developed scientific methods where "universals came out of practical, experimental work" and "theories are formulated after discoveries."[3] In his debate with Avicenna, Biruni made the first real distinction between a scientist and a philosopher, referring to Avicenna as a philosopher and considering himself to be a mathematical scientist.  Biruni's scientific method was similar to the modern scientific method in many ways, particularly his emphasis on repeated experimentation. Biruni was concerned with how to conceptualize and prevent both systematic errors and random errors, such as "errors caused by the use of small instruments and errors made by human observers”.  He argued that if instruments produce random errors because of their imperfections or idiosyncratic qualities, then multiple observations must be taken, analyzed qualitatively, and on this basis, arrive at a "common-sense single value for the constant sought", whether an arithmetic mean or a "reliable estimate."

Natural philosophy

Biruni and Avicenna (Ibn Sina), who are regarded as two of the greatest polymaths in Persian history, were both colleagues and knew each other since the turn of the millennium. Biruni later engaged in a written debate with Avicenna, with Biruni criticizing the Peripatetic school for its adherence to Aristotelian physics and natural philosophy, while Avicenna and his student Ahmad ibn 'Ali al-Ma'sumi respond to Biruni's criticisms in writing.

This debate has been preserved in a book entitled al-As'ila wal-Ajwiba (Questions and Answers), in which al-Biruni attacks Aristotle's theories on physics and cosmology, and questions almost all of the fundamental Aristotelian physical axioms. For example, he rejects the notion that heavenly bodies have an inherent nature and asserts that their "motion could very well be compulsory"; maintains that "there is no observable evidence that rules out the possibility of vacuum"; and states that there is no inherent reason why planetary orbits must be circular and cannot be elliptical. He also argues that "the metaphysical axioms on which philosophers build their physical theories do not constitute valid evidence for the mathematical astronomer." This marks the first real distinction between the vocations of the philosopher-metaphysician (which he labelled Aristotle and Avicenna as) and that of the mathematician-scientist (which al-Biruni viewed himself as).[not in citation given] In contrast to the philosophers, the only evidence that al-Biruni considered reliable were either mathematical or empirical evidence, and his systematic application of rigorous mathematical reasoning later led to the mathematization of Islamic astronomy and the mathematization of nature.

Biruni began the debate by asking Avicenna eighteen questions, ten of which were criticisms of Aristotle's On the Heavens, with his first question criticizing the Aristotelian theory of gravity for denying the existence of levity or gravity in the celestial spheres, and the Aristotelian notion of circular motion being an innate property of the heavenly bodies.  Biruni's second question criticizes Aristotle's over-reliance on more ancient views concerning the heavens, while the third criticizes the Aristotelian view that space has only six directions. The fourth question deals with the continuity and discontinuity of physical bodies, while the fifth criticizes the Peripatetic denial of the possibility of there existing another world completely different from the world known to them. In his sixth question, Biruni rejects Aristotle's view on the celestial spheres having circular orbits rather than elliptic orbits. In his seventh question, he rejects Aristotle's notion that the motion of the heavens begins from the right side and from the east, while his eighth question concerns Aristotle's view on the fire element being spherical. The ninth question concerns the movement of heat, and the tenth question concerns the transformation of elements.

The eleventh question concerns the burning of bodies by radiation reflecting off a flask filled with water, and the twelfth concerns the natural tendency of the classical elements in their upward and downward movements. The thirteenth question deals with vision, while the fourteenth concerns habitation on different parts of Earth. His fifteenth question asks how two opposite squares in a square divided into four can be tangential, while the sixteenth question concerns vacuum. His seventeenth question asks "if things expand upon heating and contract upon cooling, why does a flask filled with water break when water freezes in it?" His eighteenth and final question concerns the observable phenomenon of ice floating on water.

After Avicenna responded to the questions, Biruni was unsatisfied with some of the answers and wrote back commenting on them, after which Avicenna's student Ahmad ibn 'Ali al-Ma'sumi wrote back on behalf of Avicenna.

Biruni wrote the criticism on Aristotle's followers in his time:

The trouble with most people is their extravagance in respect of Aristotle's opinions; they believe that there is no possibility of mistakes in his views, though they know that he was only theorizing to the best of his capacity.

Masudic Canon


In 1031, Biruni completed his extensive encyclopaedia Kitab al-Qanun al-Mas'udi (Latinized as Canon Mas’udicus).[28] It was an extensive encyclopedia on astronomy, geography, and engineering, named after Mas'ud, son of Mahmud of Ghazni, to whom he dedicated the book.


Will Durant wrote the following on al-Biruni's contributions to Islamic astronomy:

"He wrote treatises on the astrolabe, the planisphere, the armillary sphere; and formulated astronomical tables for Sultan Masud. He took it for granted that the earth is round, noted “the attraction of all things towards the center of the earth,” and remarked that astronomic data can be explained as well by supposing that the earth turns daily on its axis and annually around the sun, as by the reverse hypothesis”.

Astronomical observations

In the Masudic Canon,[28] he recorded his astronomical findings and formulated astronomical tables. The book introduces the mathematical technique of analysing the acceleration of the planets, and first states that the motions of the solar apogee and the precession are not identical. Biruni also discovered that the distance between the Earth and the Sun is larger than Ptolemy's estimate, on the basis that Ptolemy disregarded annular eclipses.

Al-Biruni also introduced a new method of observation called the "three points observation". A later Muslim polymath astronomer, Taqi al-Din, described the three points as "two of them being in opposition in the ecliptic and the third in any desired place." Prior to al-Biruni, astronomers used the relatively inaccurate method of Hipparchus who used the intervals of seasons for calculating solar parameters. Al-Biruni's new "three points observation" was an important contribution to practical astronomy, and was still used six centuries later by Taqi al-Din, Tycho Brahe and Nicolaus Copernicus to calculate the eccentricity of the Sun's orbit and the annual motion of the apogee.

In contrast to Ptolemy, who selected the observations which agreed with his theory and omitted the observations he was discarding, Biruni treated errors in a more scientific manner, providing details on all of his observations, regardless of whether he agreed with the results. He was also concerned with maintaining a high degree of accuracy when it came to rounding errors in calculations, and he always attempted to avoid the manipulation of observed empirical data.[7]

Geodesy and geography

Biruni is regarded as the father of geodesy.  Biruni solved a complex geodesic equation in order to accurately compute the Earth's circumference, which were close to modern values of the Earth's circumference.  John J. O'Connor and Edmund F. Robertson write in the MacTutor History of Mathematics archive:

"Important contributions to geodesy and geography were also made by Biruni. He introduced techniques to measure the earth and distances on it using triangulation. He found the radius of the earth to be 6339.6 km, a value not obtained in the West until the 16th century. His Masudic canon contains a table giving the coordinates of six hundred places, almost all of which he had direct knowledge”.

In the Masudi Canon,  Biruni's estimate of 6,339.9 km for the Earth radius was only 16.8 km less than the modern value of 6,356.7 km. In contrast to his Greek, Indian and Islamic predecessors who measured the Earth's circumference by sighting the Sun simultaneously from two different locations, Biruni developed a new method of using trigonometric calculations based on the angle between a plain and mountain top which yielded more accurate measurements of the Earth's circumference and made it possible for it to be measured by a single person from a single location.  Biruni's method was intended to avoid "walking across hot, dusty deserts" and the idea came to him when he was on top of a tall mountain near Nandana in India,  now located near Pind Dadan Khan, Jhelum District, Punjab, Pakistan.  From the top of the mountain, he sighted the angle between the horizon and the horizontal which, along with the mountain's height (which he calculated beforehand), he applied to the law of sines formula. This was the earliest known use of this angle, and the earliest practical use of the law of sines.  He also made use of algebra in his calculation.  His method can be summarized as follows:

He first calculated the height of the mountain by going to two points at sea level with a known distance apart and then measuring the angle between the plain and the top of the mountain for both points. He made both the measurements using an astrolabe. He then used the following trigonometric formula relating the distance (d) between both points with the tangents of their angles (θ) to determine the height (h) of the mountain


He then stood at the highest point of the mountain, where he measured the angle to the horizon using an astrolabe.[39] He applied the values he obtained for this angle and the mountain's height to the following method in order to calculate the Earth's radius



Biruni accurately determined the Earth radius by formulating a trigonometric equation relating the angle between the true horizon and astronomical horizon observed from the top of a mountain to the height of that mountain.

H = Highest point of mountain

L = Lowest point of mountain

T = Lowest point of true horizon visible from point H

A = Any imaginary point along astronomical horizon visible from point H

P = Imaginary point along line HT that is horizontal to point L

O = Centre of Earth

Since the values for the height HL and dip angle AHT are known, these can be applied to the law of sines to algebraically determine the length of line LP


The length of line HP can be found using the Pythagorean theorem, while LP = PT since they are both tangents to the circle from point P. The Earth's radius OT can finally be found algebraically by applying the law of sines again


He further simplified his method into the following trigonometric formula:[39]



R = Earth radius

h = height of mountain

θ= angle of the horizon below the horizontal




Until the 10th century, history most often meant political and military history, but this was not so with Biruni (973-1048). In his Kitab fi Tahqiq ma li'l-Hind (Researches on India), also known as Indica, he did not record political and military history in any detail, but wrote more on India's cultural, scientific, social and religious history.  Biruni is now regarded as the father of Indology.


Abū Rayhān Bīrūnī (973-1048), a Muslim scholar, carried out extensive, personal investigations of the peoples, customs, and religions of the Indian subcontinent. He has been described as the first anthropologist while other writers have said that he hardly qualifies as an anthropologist in the conventional sense. He wrote detailed comparative studies on the anthropology of religions and cultures in the Middle East, Mediterranean and especially South Asia. Biruni's anthropology of religion was only possible for a scholar deeply immersed in the lore of other nations.

While living in Ghazna, Al-Biruni performed his first ethnographic fieldwork on the topic of Hinduism in India.  Coming from an Islamic faith in a period of significant division between religions, specifically between monotheism and polytheism, Al-Biruni’s work as an objective observer of Hinduism in India is recognized as exceedingly progressive. Al-Biruni spent time in India researching culture, religion and language from 1017 until 1031, resulting in an ethnography, al-Hind, also translated as the Description of India.  Most commonly known as a mathematician, astrologer, historian and scientist, Al-Biruni used his interdisciplinary interests from an anthropological perspective before anthropology existed as a discipline. Living during “the high noon of Islamic cultural and scientific achievements,” Al-Biruni placed a focus on modern anthropological interests including caste, the class system, rites and customs, cultural practice, and women’s issues.  Through this modern practice, Al-Biruni used the concepts of cross cultural comparison, inter-cultural dialogue and phenomenological observation which have become commonplace within anthropology today.  Within al-Hind, Al-Biruni does not pass judgment on the Indian culture or the Hindu faith, but rather speaks through them. Not only did Al-Biruni conduct what has been recognized as the first ethnographic fieldwork, he was also the first Muslim to study the Hindu tradition, developing an interest in religious coexistence. This interest and knowledge spanning multiple disciplines contributed to Al-Biruni’s cultural awareness, evident within al-Hind.

In regard to Al-Biruni’s impressive curriculum vitae, he has now been referred to as al-Ustadh or “the Master” among the multitude of disciplines he has influenced.  Through Al-Biruni’s contributions to anthropology, his understanding that “there is a common human element that makes all cultures distant relatives” is quite evident.  As a result of Al-Biruni’s curiosity in the interconnection of cultures, he sought to critically examine religion, a commonality he noted between all cultures. Al-Biruni remained committed to his scientific and literary works until his death sometime after 442/1050CE, presumably in Ghazna.  It is unclear how long or how severe Al-Biruni’s imprisonment was in Ghazna. Fortunately, detainment did not restrict Al-Biruni from completing an estimated total of 180 scientific and literary works.  Among this compilation of works, Al-Biruni wrote on the topics of astronomy, geography, religion, anthropology, and history, to name a few. As Al-Biruni’s concentration was often specifically through an Islamic lens, he identified a social pattern of similarities across cultural and religious lines through his studies. With a focus on comparative religion, Al-Biruni sought to accomplish a comprehensive understanding of foreign societies as a “staunch believer in the truth.” This cultural perception served to promote Al-Biruni’s anthropological ideology within and through an array of his works.

Islamic anthropology

Much of Al-Biruni’s works, in addition to the physical sciences, were dedicated to a “phenomenological and historical study of religion.” Through this comprehensive and critical analysis of religion, Al-Biruni developed an anthropological methodology as a means of approaching the cultural issues surrounding Islam. Referring back to Al-Biruni’s literary work, al-Hind, in which comparative analysis opened many Muslim eyes to an unknown culture, one scholar suggests that “he (Al-Biruni) was probably Islamic civilization’s first cultural anthropologist." Upon reflection, social scientific works such as al-Hind have provided a “careful phenomenological approach to our contemporary global interest in inter-religious understanding.” Religion and the Arts, an academic journal, recognizes Al-Biruni’s work as a “curious and intentionally comprehensive approach to gathering and analyzing”.  This recognition of Al-Biruni’s work seems to equate with modern anthropology’s ethnographic fieldwork. It is astounding the early practices and methods Al-Biruni contributed to such an array of disciplines centuries ago.

While Al-Biruni produced progressive and influential works centuries ago in the medieval era, his work continues to be recognized as foundational and revered for original and profound thought across academic disciplines to this day. “The Master” has been remembered as “one of the most extraordinary scientific and mathematical geniuses of all time” as well as “one of the greatest scholars of mediaeval Islam, and certainly the most original and profound.” The contribution that Al-Biruni has had upon academia is irrefutable. He laid a ground-work for anthropology and sociology centuries before they were recognized as disciplines. While Al-Biruni’s works coincided quite intimately with his faith, as the works of many Muslims do, this did not prohibit an unbiased mind and unlimited interest in the unknown. It is difficult to place Al-Biruni within a single branch of Anthropology. Rather, he could very well be perceived as a cultural, linguistic, or biological anthropologist by today’s standards. Thanks to Al-Biruni’s broad academic interests, the field of anthropology is now affluent with those similarly seeking answers to previously overlooked questions regarding cross cultural understanding. This healthy curiosity of social patterns, culture, tradition, religion, language and science, furthered by Al-Biruni and his peers, has contributed to innumerable advancements in academia.

Biruni developed a sophisticated methodology for his anthropological studies. For example, he wrote the following in the opening passages of his Indica:

"No one will deny that in questions of historic authenticity hearsay does not equal eyewitness; for in the latter the eye of the observer apprehends the substance of that which is observed, both in the time when and in the place where it exists, whilst hearsay has its peculiar drawbacks."

He was also aware that there are limitations to eye-witness accounts:

"The object of eye-witness can only be actual momentary existence, whilst hearsay comprehends alike the present, the past and the future".

Biruni's tradition of comparative cross-cultural study continued in the Muslim world through to Ibn Khaldun's work in the 14th century.

Comparative religion

In religious education, Biruni was a pioneer of comparative religion. According to Arthur Jeffery, "It is rare until modern times to find so fair and unprejudiced a statement of the views of other religions, so earnest an attempt to study them in the best sources, and such care to find a method which for this branch of study would be both rigorous and just."

In the introduction to his Indica, Biruni himself writes that his intent behind the work was to engage dialogue between Islam and the Indian religions, particularly Hinduism as well as Buddhism. He writes:

"Abu-Sahl at-Tiflisi incited me to write down what I know about the Hindus as a help to those who want to discuss religious questions with them, and as a repertory of information to those who want to associate with them. We think now that what we have related in this book will be sufficient for anyone who wants to converse with the Hindus, and to discuss with them questions of religion, science or literature, on the very basis of their own civilisation."

Biruni was aware that statements about a religion would be open to criticism by its adherents, and insisted that a scholar should follow the requirements of a strictly scientific method. According to William Montgomery Watt, Biruni "is admirably objective and unprejudiced in his presentation of facts" but "selects facts in such a way that he makes a strong case for holding that there is a certain unity in the religious experience of the peoples he considers, even though he does not appear to formulate this view explicitly." Biruni argued that Hinduism was a monotheistic faith like Islam, and in order to justify this assertion, he quotes Hindu texts and argues that the worship of idols is "exclusively a characteristic of the common people, with which the educated have nothing to do." He writes

"The educated among the Hindus abhor anthropomorphisms of this kind, but the crowd and the members of the single sects use them most extensively."

"The Hindus believe with regard to God that he is one, eternal, without beginning and end, acting by free-will, almighty, all-wise, living, giving life, ruling, preserving; one who in his sovereignty is unique, beyond all likeness and unlikeness, and that he does not resemble anything nor does anything resemble him."

Biruni argued that the worship of idols "is due to a kind of confusion or corruption." He writes:

"The physical images are monuments in honour of certain much venerated persons, prophets, sages, angels, destined to keep alive their memory when they are absent or dead, to create for them a lasting place of grateful veneration in the hearts of men when they die."

According to Watt, Biruni "goes on to maintain that in the course of generations the origin of the veneration of the images is forgotten, and further that the ancient legislators, seeing that the Veneration of images is advantageous, made it obligatory for the ordinary. He mentions the view of some people that, before God sent Prophets, all mankind were idol-worshippers, but he apparently does not presumably held that, apart from the messages transmitted by prophets, men could know the existence and unity of God by rational methods of philosophy." Biruni argued that "the Hindus, no less than the Greeks, have philosophers who are believers in monotheism."

Other comparisons between Islamic theology and Indian theology include the following comparison between the Qur'an and the Indian religious scriptures in the "On the Configuration of the Heavens and the Earth According to [Indian] astrologers" chapter of the Indica

"[The views of Indian astrologers] have developed in a way which is different from those of our [Muslim] fellows; this is because unlike the scriptures revealed before it, the Qur'an does not articulate on this subject [of astronomy], or any other [field of] necessary [knowledge] any assertion that would require erratic interpretations in order to harmonize it with that which is known by necessity."

"[In contrast, the religious and transmitted books of the Indians do indeed speak] of the configuration of the universe in a way which contradicts the truth which is known to their own astrologers."

Biruni also had an interest in studying Hermeticism and often criticized its religious views. He also compared Islam with pre-Islamic religions, and was willing to accept certain elements of pre-Islamic wisdom which would conform with his understanding of the Islamic spirit.

Biruni also compared Islam and Christianity, citing passages from the Qur'an and Bible which state that their followers should always speak the truth:[51]

"That man only is praiseworthy who shrinks from a lie and always adheres to the truth, enjoying credit even among liars, not to mention others. It has been said in the Koran, "Speak the truth, even if it were against yourselves" (Sura, 4, 134); and the Messiah expresses himself in the Gospel to this effect: "Do not mind the fury of kings in speaking the truth before them. They only possess your body, but they have no power over your soul." (cf. St. Matt. X. 18,19,28; St. Luke xii.4)."

Historical method

In his Kitab fi Tahqiq ma li'l-Hind (Researches on India), he was the first to distinguish between the historical method and the scientific method.

Islamic theology

In the Indica, while comparing the Qur'an to the Hindu scriptures, Biruni assigned to the Qur'an a separate and autonomous realm of its own and held that:[52]

"[the Qur'an] does not interfere in the business of science nor does it infringe on the realm of science."

In Chapter 47 of his India, entitled "On Vasudeva and the Wars of the Bharata," Biruni attempted to give a naturalistic explanation as to why the struggles described in the Mahabharata "had to take place." He explains it using natural processes that include biological ideas related to evolution, which has led several scholars to compare his ideas to Darwinism and natural selection.  One of these ideas corresponds to "the central idea of Malthus on the disproportion between the increase in the rates of reproduction and means of subsistence," as in the following statement

"The life of the world depends upon the sowing and procreating. Both processes increase in the course of time, and this increase is unlimited, whilst the world is limited."

He then applies this principle to living things

"When a class of plants or animals does not increase any more in its structure, and its peculiar kind is established as a species of its own, when each individual of it does not simply come into existence once and perish, but besides procreates a being like itself or several together, and not only once but several times, then this will as single species of plants or animals occupy the earth and spread itself and its kind over as much territory as it can find."

Biruni then describes the idea of artificial selection

"The agriculturist selects his corn, letting grow as much as he requires, and tearing out the remainder. The forester leaves those branches which he perceives to be excellent, whilst he cuts away all others. The bees kill those of their kind who only eat, but do not work in their beehive."

Birune then applies this idea to nature, hence "some presentiment of Darwin's idea of natural selection might be detected" in the next paragraph by Biruni

"Nature proceeds in a similar way; however, it does not distinguish for its action is under all circumstances one and the same. It allows the leaves and fruit of the trees to perish, thus preventing them from realising that result which they are intended to produce in the economy of nature. It removes them so as to make room for others."


Among his writings on geology, Bīrūnī observed the geology of India and discovered that the Indian subcontinent was once a sea, hypothesizing that it became land through the drifting of alluvium. He wrote:

"But if you see the soil of India with your own eyes and meditate on its nature, if you consider the rounded stones found in earth however deeply you dig, stones that are huge near the mountains and where the rivers have a violent current: stones that are of smaller size at a greater distance from the mountains and where the streams flow more slowly: stones that appear pulverised in the shape of sand where the streams begin to stagnate near their mouths and near the sea — if you consider all this you can scarcely help thinking that India was once a sea, which by degrees has been filled up by the alluvium of the streams."

This is in agreement with the theory of the modern geological theory of continental drift, where the Indian subcontinent moved northwards and joined the Asian landmass, creating the Himalayas, and is still moving north-eastwards.

Theoretical astronomy

In 1030, Biruni discussed the Indian heliocentric theories of Aryabhata, Brahmagupta and Varahamihira in his Indica. He described Indian mathematics as a "mix of common pebbles and costly crystals". Biruni noted that the question of heliocentricity was a philosophical rather than a mathematical problem.  Abu Said al-Sijzi, a contemporary of Biruni, suggested the possible heliocentric movement of the Earth around the Sun, which Biruni did not reject.  Biruni agreed with the Earth's rotation about its own axis, and while he was initially neutral regarding the heliocentric and geocentric models, he considered heliocentrism to be a philosophical problem.  He remarked that if the Earth rotates on its axis and moves around the Sun, it would remain consistent with his astronomical parameters

"Rotation of the earth would in no way invalidate astronomical calculations, for all the astronomical data are as explicable in terms of the one theory as of the other. The problem is thus difficult of solution."

He discussed his idea of history in The Chronology of the Ancient Nations, also known as The Remaining Signs of Past Centuries. It is a comparative study of calendars of different cultures and civilizations, interlaced with mathematical, astronomical, and historical information, exploring the customs and religions of different peoples. Completed in AD 1000 (AH 390/1), it is the first major work of Al-Biruni's, compiled in Gorgan, at the court of Qabus, when he was in his late twenties.

Mathematical geography

Discussing the astrolabe, Al-Biruni considers the orthographic cylindrical projection as his own invention, expanding upon the work of Al-Saghani.

Biruni was regarded as the most skilled when it came to mapping cities and measuring the distances between them, which he did for many cities in the Middle East and western Indian subcontinent. He often combined astronomical readings and mathematical equations, in order to develop methods of pin-pointing locations by recording degrees of latitude and longitude. He also developed similar techniques when it came to measuring the heights of mountains, depths of valleys, and expanse of the horizon, in The Chronology of the Ancient Nations.

Book of Coordinates


Mathematical geography

In the Book of Coordinates, Biruni estimated the rate at which the Earth's rotation accelerates, the rate at which the Earth tilts, and the rate of lunar acceleration of the Moon. His calculations yield the "acceleration of the Earth's spin as -26.5  5.8 parts in 109 per century" and the rate of change in the axial tilt as "-47.9  2.0 sec per century." He also calculated the Moon's lunar acceleration as "-46.4  6.0 sec per century”.


Biruni held that astronomy could generate its own astrophysics based on observations and mathematics, and that it does not need to import physical principles from philosophical physics, such as Aristotelian physics. In astrophysics and the celestial mechanics field of physics, Biruni described the Earth's gravitation as

"The attraction of all things towards the centre of the earth."

He also discovered that gravity exists within the heavenly bodies and celestial spheres, and he criticized Aristotle's views of them not having any levity or gravity and of circular motion being an innate property of the heavenly bodies.

He argued that as all objects are attracted towards the centre, if the heavenly bodies did not possess gravity, then they would have also fallen down to the centre. He therefore suggests that the heavenly bodies must have gravity of their own to interconnect them to one another in order to prevent them from falling down towards the centre. He also rejected Aristotle's view that there was a "natural place" for every substance, such as water's natural place being above the earth, as Biruni argued that there was no natural place for any substance.

Experimental mechanics

Biruni was the first to apply experimental scientific methods to mechanics, especially the fields of statics and dynamics, particularly for determining specific weights, such as those based on the theory of balances and weighing. He also played an instrumental role in various Islamic innovations in mechanics, such as the study of statics "by using the dynamic approach so that two trends - statics and dynamics - turned out to be inter-related within a single science, mechanics." He was also one of the Islamic scientists responsible for combining for dynamics with hydrostatics to give birth to hydrodynamics.

In the statics field of mechanics, the notion of specific gravity is defined and employed by Biruni in his Ayin-Akbari. Although this concept is implicit in Archimedes' work on hydrostatics, the term is not used or defined by Archimedes. Biruni measured the specific gravities of eighteen gemstones, and discovered that there is a correlation between the specific gravity of an object and the volume of water it displaces.  He was also "the first in history to introduce checking tests in the practice of experiments". He measured the weights of various liquids, and recorded the differences in weight between freshwater and salt water, and between hot water and cold water.

During his experiments, he invented the conical measure,  in order to find the ratio between the weight of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding metals, which are very close to modern measurements.

Theoretical mechanics

In the mechanics field of theoretical physics, Biruni appears to be the earliest[citation needed] to cite movement and friction as the cause of heat, which in turn produces the element of fire, and a lack of movement as the cause of cold near the geographical poles:

"The earth and the water form one globe, surrounded on all sides by air. Then, since much of the air is in contact with the sphere of the moon, it becomes heated in consequence of the movement and friction of the parts in contact. Thus there is produced fire, which surrounds the air, less in amount in the proximity of the poles owing to the slackening of the movement there." In dynamics and kinematics, Biruni was the first to realize that acceleration is connected with non-uniform motion, which is part of Newton's second law of motion.


In optics, Biruni was one of the first, along with Ibn al-Haytham, to postulate that the speed of light is finite. Biruni was also the first to discover that the speed of light is much faster than the speed of sound.

Other contributions in astronomy


Observational astronomy

Biruni was the first to conduct elaborate experiments related to astronomical phenomena. He supposed the Milky Way galaxy to be a collection of numerous nebulous stars, and in Khorasan, he observed and described the solar eclipse on 8 April 1019, and the lunar eclipse on 17 September 1019, in detail, and gave the exact latitudes of the stars during the lunar eclipse.


Biruni invented a number of astronomical instruments. He wrote the first treatises on the planisphere (the earliest star chart) and the orthographical astrolabe, as well as a treatise on the armillary sphere, and he was able to mathematically determine the direction of the Qibla from any place in the world. He also wrote an early treatise on the sextant.

He also invented an early hodometer, and the first mechanical lunisolar calendar computer which employed a gear train and eight gear-wheels. These were early examples of fixed-wired knowledge processing machines.

In his Exhaustive Treatise on Shadows, he explained the calculation of Salah prayer times according to the shadow cast by the gnomon of a sundial.

The first description of an "observation tube" is found in a work of Biruni, in a section "dedicated to verifying the presence of the new crescent on the horizon." Though these early observation tubes did not have lenses, they "enabled an observer to focus on a part of the sky by eliminating light interference." These observation tubes were later adopted in Latin-speaking Europe, where they influenced the development of the telescope.

Refutation of astrology

He made a semantic distinction between astronomy and astrology in one of his works, following an earlier Greek source.[86] In a later work, he wrote a refutation of astrology. His reasons for refuting astrology included the methods used by astrologers being conjectural rather than empirical, and also due to the views of astrologers conflicting with orthodox Islam.

Theoretical astronomy

In his debate with Avicenna, Biruni criticized several of Aristotle's astronomical views, such as that heavenly bodies move in circular orbits. He also pointed out that the heavens could be elliptical rather than spherical.

Other contributions in Earth sciences




Biruni made a number of contributions to the Earth sciences. In particular, he has made significant contributions to cartography, geodesy, geography, geology and mineralogy.

By the age of 22, Biruni had written several short works, including a study of map projections, Cartography, which included a method for projecting a hemisphere on a plane. He introduced the use of three rectangular coordinates to define a point in three-dimensional space, and also developed ideas which are seen as an anticipation of the polar coordinate system.

Geodesy and geography

Biruni discussed human geography and the planetary habitability of the Earth. He hypothesized that roughly a quarter of the Earth's surface is habitable by humans, and also argued that the shores of Asia and Europe were "separated by a vast sea, too dark and dense to navigate and too risky to try" in reference to the Atlantic Ocean and Pacific Ocean.


Al-Biruni introduced the scientific method into mineralogy in his Kitab al-Jawahir (Book of Precious Stones), where he was "the most exact of experimental scientists”. The book described minerals such as stones and metals in depth, and was regarded as the most complete book on mineralogy in his time. He conducted hundreds of experiments to gauge the accurate measurements of items he catalogued, and he often listed them by name in a number of different languages, including Arabic, Persian, Greek, Syriac, Hindi, Latin, and other languages. In the Book of Precious Stones, he catalogued each mineral by its color, odor, hardness, density and weight. The weights for many of these minerals he measured were correct to three decimal places of accuracy, and were almost as accurate as modern measurements for these minerals.

Contributions in other fields

Biomedical sciences

In the biomedical sciences, al-Biruni's Kitab al-Saidana fi al-Tibb was an extensive medical and pharmacological encyclopedia which synthesized Islamic medicine with Indian medicine. His medical investigations included one of the earliest descriptions on Siamese twins.

The Kitab-al-Saidana was also a materia medica which was celebrated for its in-depth botanical studies of minerals and herbs.  It was the earliest to describe the eating of several fungi, including truffles, which are a type of hypogeous fungi. The earliest documented description of khat also dates back to the Kitab al-Saidana, in which al-Bīrūnī wrote that khat is:

"a commodity from Turkestan. It is sour to taste and slenderly made in the manner of batan-alu. But qat is reddish with a slight blackish tinge. It is believed that batan-alu is red, coolant, relieves biliousness, and is a refrigerant for the stomach and the liver."

Experimental psychology

Al Biruni on a 1973 Afghan post stamp commemorating his one thousandth anniversary

In Islamic psychology, Biruni was a pioneer of experimental psychology, for his use of empirical observation and experimentation in his discovery of the concept of reaction time, which he described as follows:[9]

"Not only is every sensation attended by a corresponding change localized in the sense-organ, which demands a certain time, but also, between the stimulation of the organ and consciousness of the perception an interval of time must elapse, corresponding to the transmission of stimulus for some distance along the nerves."

Islamic law

In Islamic law and jurisprudence, Biruni understood natural law as the law of the jungle. He argued that the antagonism between human beings can only be overcome through a divine law, which he believed to have been sent through the prophets of Islam.

Islamic theology

In Islamic theology, it is uncertain whether Biruni was a follower of the orthodox Ash'ari school of Sunni Islam, or a follower of Shia Islam. He is also thought to have associated with Maturidi theologians and was sympathetic towards Ismailis. He was critical, however, of Mutazili theologians, particularly al-Jahiz and Zurqan, and he also criticized Muhammad ibn Zakarīya Rāzi's sympathy for Manichaeanism.

He argued that the possession of intellect makes humans superior to animals and that God "placed humans as stewards over Earth and other terrestrial life-forms." He also considered hearing and sight to be the two most important senses, as they allow humans to "observe the signs of God's divine wisdom in his creations" and "receive the word of God and his command.”



In linguistics, al-Biruni could speak, read and write in a number of different languages, including Persian, Arabic, Greek, Hebrew, Sanskrit - where he became so proficient that the pandits called him "Vidya Sagar" meaning "Ocean of Learning- besides his native Khwarezmian language(an East Iranian languages). He was also conversant in standard Persian, Sanskrit, Hebrew, and Syriac in addition to the Arabic and could also speak some Hindi and Latin.[citation needed]



"Alberuni must rank high in any list of world's great scholars. No history of mathematics, astronomy, geography, anthropology, or history of religion is complete without acknowledgment of his immense contribution. One of the outstanding minds of all time, distinguished to a remarkable degree by the essential qualities which have made possible both science and social studies, Alberuni is the demonstration of the universality and timelessness of a great mind. One could compile a long series of quotations from Alberuni written a thousand years ago that anticipate supposedly modern intellectual attitudes and methods.”