What scientific discoveries and inventions were made during the Islamic Golden Age?
Algebra
Algebra was invented by al-Khwarizmi. Some dispute this claim as the Greek mathematician Diophantus and the Indian mathematician Brahmagupta were clearly using algebraic methods to solve complex equations centuries before al-Khwarizmi. The difference, however, is that al-Khwarizmi laid out the fundamental rules of the discipline in his Kitab al-Jebr and recognized it as a branch of mathematics in its own right.
Algorithms
The algorithm, which means the concept of laying out rules and formulating steps to solve a problem, was the invention of the famous mathematician al-Khwarizmi which he devised while solving algebraic equations. Modern computers would not have been possible without them.
Big Science
The reliance of scientific progress on large-scale state-sponsored projects (Big Science) was a tradition first laid down by the Arab scientists and Abbasid Caliphs, Caliph al-Ma’mun to be specific. He formed a team of his best astronomers and mathematicians -comprising of Sanad ibn al-Yahudi, Yahya ibn abi Mansur, al-Abbas al-Jawhari, al-Farghani and the esteemed al-Khwarizmi - and set them to the task of building the first observatory of the Islamic world, northwest of Baghdad. These astronomers then proceeded to make observations of the night sky and produced the most accurate star-chart of the Middle Ages. They would also go on to calculate the circumference of the earth and draw the most accurate map of the world, all on the state’s expense.
Chemistry
Yes, the entire field of chemistry owes its existence to Jabir bin Hayyan, an 8th century chemist who was the first person to distinguish chemistry from alchemy and establish it as an empirical science. He also left behind the ‘Jabirian Corpus’, a mammoth collection of scores of volumes and manuscripts containing records of his experiment, observations and findings; properties of substances and several new compounds that he discovered.
Circumference of the earth
This was the remarkable result of the genius of the 11th century polymath al-Biruni. Using nothing but a mountain and a square wooden board with a ruler dangling from one of its corners he calculated the circumference of the earth to be 25,000 miles, he was off the correct value by just 100 miles.
Classification of substances
Although substances of all sorts were being classified long before the advent of Islam, it was the physician al-Razi who changed the way this was done. Previously the Greeks used to classify all substances on purely philosophical musings but al-Razi was the first person to classify substances based on their physical properties. For example: for chemical substances he derived six categories; spirits, metals, stones, atriments, boraces and salts.
Clinical trial
The earliest known clinical trial involving a control group was also carried out by al-Razi. He selected two sets of patients suffering from meningitis and treated the first with bloodletting but not the second. After continuing his treatment for several days he reached the conclusion that bloodletting was an effective treatment for meningitis as the first group of people was cured of the illness while the second was not.
Cosine rule
The famous Cosine rule, which allows the sides of a triangle to be calculated provided an angle and the other two sides are known was derived for the first time by al-Kashi in the 15th century.
Cryptanalysis
The field of cryptanalysis or code-breaking was created by the polymath al-Kindi. He invented the frequency analysis method by which the frequency of the symbols in the code was analysed and compared with the frequency of letters in the original language of the code.
Dream theory
The influence of the subconscious mind on dreams was first documented by al-Kindi. He also attempted to interpret dreams and devised a crude form of Freudian psychology to do so.
Egyptology
There is convincing evidence that the tenth century ibn Wahshiyya was the first Egyptologist. He conducted extensive research on the pyramids and deciphered a substantial number of the hieroglyphs.
Indology
The study of the history and culture of the Subcontinent was pioneered by al-Biruni in his The History of India.
Intromission theory of vision
This was another contribution to science of the great Ibn al-Haytham. Previously the Greeks believed in the ‘emission theory’, which meant that the eyes sent out light rays that allowed us to see. With some clever reasoning Ibn al-Haytham proved it wrong and gave the intromission theory, according to which light from our surroundings entered our eyes that allowed us to see.
Lamarckist evolution
A rudimentary theory of Lamarckist evolution was proposed by the biologist al-Jahith who speculated how their environments could influence animals living in them, further arguing that acquired characteristics could be passed down to children.
Length of the solar year
This was the work of the Persian poet and mathematician, Umar Khayyam. In his twenties, using a sundial, a water clock and an astrolabe, he measured the length of the solar year to 365.24219858156 days. His figure was incredibly precise and accurate to the modern figure to six decimal places. He also used this figure to make the Jalali calendar several years later. It’s worth noting that this calendar is even more precise than the modern Gregorian calendar.
Maragha revolution
The Maragha revolution refers to the findings of the astronomers of the Maragha observatory in Persia. Lead by Nasr al-Din Tusi their findings included the Tusi-couple, a geometric model that could be applied to astronomy. It cleared away the mess of Ptolemy’s complicated system of equants and epicycles that he used to describe the geocentric model of the universe and laid the mathematical foundation on which Copernicus would propose the heliocentric model of the universe.
Music therapy
The therapeutical value of music was another contribution to science of al-Kindi. He reportedly used it to cure patients with peculiar ailments, most famously a quadriplegic boy.
Programmable machine
This may come as a surprise to you but the first programmable machine was a robotic flute player constructed by the Banu Musa brothers, a trio of gifted scientists who had a specialty for mechanical devices. Known as ‘The Instrument that Plays by Itself’, it was a complicated assemblage of tiny levers, drums and valves that ran on water and air and could be set to play a tune.
Psychology and psychotherapy
In an age when the rest of the world considered patients with mental disorders to be possessed by spirits, the great physician al-Razi sought to seek medical solutions to their predicaments. He ran psychiatric wards in his Baghdad hospitals and due to the many progressive cures he devised he is often referred to as the Father of Psychology and Psychotherapy.
Pulmonary transit
The process of pulmonary transit was the discovery of Ibn Nafis who described how blood went from the right chamber of the heart to the left via the lungs. This was a revolutionary discovery at that time and laid the groundwork on which William Harvey would discover the entire process of blood circulation.
Scientific method
The scientific method, a set of rules governing how science is conducted, was devised by the greatest physicist in the era between Archimedes and Sir Isaac Newton, Ibn al-Haytham, though wrongly attributed to Francis Bacon. The scientific method involved obtaining knowledge through observation and measurement followed by formulation of hypotheses and experimentation to arrive at a solid conclusion. This method was advocated by Ibn al-Haytham and central to all his research.
Snell’s Law
Snell’s Law of Refraction should actually be known as Sahl’s Law of Refraction because it was Ibn Sahl who discovered it. Disproving earlier theories, he showed how the refraction of a light beam in water was proportionate to the sides of the triangles that formed rather than the arc lengths.
Surgical instruments
The Andalusian surgeon al-Zahrawi was the most prolific creator of surgical instruments. He invented more than a hundred of them, including the surgical hook, spoon, rod, needle, speculum and bone-saw, not to mention the syringe, lithotomy scalpel and use of inhalant anesthesia.
