His Book of Optics (Kitab al-Manazir) is one of the most influential books in history. He proved the Intromission Theory: light enters the eye from objects, rather than the eye emitting rays (as Euclid believed).

He invented the Qamara (Dark Room), or Camera Obscura. He demonstrated that light passing through a tiny hole projects an inverted image on the opposite wall.

Centuries before Snell, Ibn Sahl accurately described the Law of Refraction—how light bends when passing through lenses. He used this math to design "Burning Mirrors" that focused light to create intense heat.

Al-Biruni developed methods to measure the density of 18 precious stones and metals with astonishing accuracy. His measurements are remarkably close to modern data found with digital instruments.

In his Book of the Balance of Wisdom, he proposed that the "heaviness" (weight) of a body varies depending on its distance from the center of the Earth—a precursor to Newton's law of gravity.

Their Book of Ingenious Devices contains 100 inventions focusing on fluid control. They pioneered conical valves and feedback control systems, essential for modern automation and plumbing.

Al-Jazari mastered the physics of water flow and gear ratios to create the famous Elephant Clock. It was a complex automated machine that tracked time with precision using water regulation.

He correctly explained that rainbows are caused by the refraction and reflection of sunlight inside raindrops. He proved this mathematically, revising Ibn al-Haytham's earlier work.