Alhazen - Physicist, Astronomer, Mathematician, Genius

Ibn al-Haythem, or Alhazen as he is most commonly referred to as, was a highly influential Arab scientist and devout muslim, who was born in Basra Iraq, and lived from 965 to 1040. Born 100 years after the development of the House of Wisdom, a centre of free thought and intellectualism in subjects ranging from medicine to astronomy in Iraq, he was brought up in the golden age of islamic knowledge. This had a real impact on him, and he went on to study islamic sciences; later on becoming mayor of Basra. This passion for science only grew stronger as he entered his adult years, and this passion lead to him making huge strides in the field of science that have greatly moulded the modern world we see today.

While acting as mayor of Basra, Alhazen made a bold and rather radical statement that he would be able to stop of River Nile from constantly flooding, with the use of a carefully constructed dam. He was therefore invited to Cairo-Egypt by Al Hakim (Egyptian ruler, also known as the mad caliph) to put this plan into action. However, upon arriving, Alhazen soon discovered that his statement may have been il-thought out, as with the technology existing at the time, a dam to stop the nile from flooding was impossible for him to do. Aware of the fact that Al hakim was a truly treacherous ruler, and would likely issue him a brutal punishment, Alhazen claimed insanity. Although this claim was believed by Al Hakim and spared him possible execution, he spent the next ten years confined to his home under house arrest. However, this punishment seemed to do no harm to Alhazen whatsoever, as he used this time to achieve great strides in many scientific fields. Most notably the field of light and optics.


"The seeker after truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them. But rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration and not the sayings of human beings whose nature is fraught with all kinds of imperfection and deficiency."

How do we see?

One of Alhazens greatest discoveries was the correct theory for how we are able to see the world. One of the leading theories of our ability of sight was "The Emission Theory". This theory states that we are able to perceive our surroundings with our eyes, because they emit a type of light that travels to an object, and bounces off of it and back to our eyes; allowing sight.

However Alhazen, through mathematical research, eye dissections, and with the use of previous research by other scientists, realised that to see, light rays must come from our surroundings; be emitted from a source such as the sun or a candle, reflect off of an object, before entering our eyes and allowing sight. This discovery was later presented in his iconic book called " The book of Optics".


This discovery opened up his eyes to other lines of scientific enquiry. If we perceived images based on the light that bounces off of an objects surface, how were we able to make out a coherent image produced by the huge amount of light that bombards our eyes from all angles? The light had to be focused in some way to make sense of it all. Although Alhazen did not discover every aspect behind the phenomenon of sight in his lifetime,  he seemingly attempted to.

This research into sight and optics lead to him creating the pinhole camera (also known as the camera obscura); a simple imaging device consisting of a small hole of light that is released into a dark room/box, allowing the image of the outside to be portrayed on the inside against a surface in a semi-focused manner. This is the general concept behind how modern cameras work today, and were developed based on this initial concept. It also gave Alhazen an idea of how lenses in our eyes reflect light towards the back of our eyes, creating an image.

Alhazen later studied how light reacts when travelling through certain mediums, and the fact that it can bend in water. This lead to his discovery of why the sky changes colour in twilight i.e. that fact that sunlight bends while travelling through the earths atmosphere as the earth changes angle, creating dark colours of orange and red at sunset and sunrise, due to the refracting of the light.


"The duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency."


The Scientific Method:

Alhazen, although most famous for his work in optics, was also a pioneer of the scientific method. This method of relying on experimentation, evidence, and past research to find answers to the worlds unanswered questions, was one he consistently used for his own quests for truth. He never took human opinions, or the "take my word for it" approach that was rife in his time seriously. He also didn't rely on divine creation or "design" to explain phenomena he was unable to explain, as most others did. He needed evidence to back up any statement, and this investigative technique is the mainstay behind modern science today.

Below: Alhazens image on modern Iraqi Dinar 
(Currency of Iraq)

Alhazen achieved many great things in his lifetime, and discovered much not just in the field of physics, but in astronomy, engineering, and geometry also; this information being scrupulously recorded by him and published in many of his books. However for someone of such intelligence, and who has affected the world to such an extent, his name has sadly not become as infamous as other great men from ptolemy, to Isaac Newton and others; many of which are in very similar lines of work, achieved less, and that have in some cases have even been given credit  for discoveries that were found out long before by Alhazen himself. However lets be thankful that such an awe-inspiringly meticulous, methodical, and brilliant man like this existed, whose ideas and thirst for truth improved our knowledge of the world around us.

-Thomas Glen

Facebook.com/goodnaturepage