c. 1015Reputable sourceWell documented
Ibn al-Haytham and the Science of Optics
On the timeline · around c. 1015 ·
What happened
Working in Cairo in the early 11th century, the Arab scholar Ibn al-Haytham (known in the West as Alhazen) wrote a great Book of Optics — a rigorous study of light, reflection, refraction, lenses, and vision. He argued that understanding must be built on careful observation and experiment rather than the authority of the ancients.
Why it matters
Ibn al-Haytham's insistence on testing ideas against evidence makes him a pioneer of the experimental scientific method, and his optics shaped the study of light for six centuries, influencing Kepler, Newton, and beyond.