Ibn-Al Haytham’s greatest contribution was the establishment of the scientific method. It is an accepted thing that every scientific fact must be supported by undeniable evidence. It was not so in Greek times where assumptions were often accepted as facts. Ibn-Al Haytham for the first time established the scientific method as we know it.
Born in Basra in 965 AD, he lived in Cairo, Egypt until his death when he was 74. He got educated in Basra which was a center of learning in the world at that time. He served in the government in Basra and became a minister of the area.
Ibn-Al Haytham was a brilliant mathematician. He developed the link between analytical geometry and algebra and derived a formula to add 100 natural numbers and proved it using geometry. His contributions to number theory include his work on perfect numbers. In his Analysis and Synthesis, Alhazen may have been the first to state that every even perfect number is of the form 2n−1(2n − 1) where 2n − 1 is prime, but he was not able to prove this result successfully.
Ibn-Al Haytham’s works were revolutionary in the field of optics. He invented the pinhole camera and debunked the Greek theory that light came out of the eyes. He also studied the phenomenon of light passing from one medium to another and explained the color of the sky at twilight. Using this concept he calculated the depth of Earth’s atmosphere- a whole millennium before it was confirmed by spaceflight. These studies of his were all packed into a book called “The Book of Optics”.
His works weren’t limited to these fields only. He was an astronomer too and wrote about the mistakes of the Ptolemaic model of how the stars and planets move and provided a more realistic view of the way the universe works. He rejected astrology as a science as astrology cannot be proven by facts or deductions.
Ibn-Al Haytham’s works had a lasting legacy. His works influenced the great Isaac Newton and many of his theories had their basis on Ibn-Al Haytham’s works. Regardless, his brilliant mind inspired countless others and it is not a stretch to say that without his research, the modern world of science that we know today would not exist.