Re: What Of Alhazens contributions to science were contributions to physics?

I am writing a report on Contributions to Physics during the Abbassid Caliphate. Abu Ali Hasan Ibn al Haitham, known to the western world as Alhazen, made significant contributions to physics during this period, but I cannot decipher what were contributions to physics and what were contributions to other sciences. Are optics, astrology (if its considered astro-physics), parts of the eye, and rainbows part of physics?

Optics (which is the science of light) can be considered part of physics, but (as with most things in life) a complete answer is more complex. Today, the field of optics is large enough that researchers in the area have their own journals and conferences. For this reason, places such as the American Institute of Physics call optics (and other sciences such as astronomy and geophysics) an allied field of physics. In the United States it is rare to find departments of optics in universities, but they are common in other parts of the world.

If we go all the way back to the time of Aristotle (about 350 BCE), what we now refer to as physics encompassed all of natural science. Organic, inorganic, biology, chemistry, everything was all part of physics. The only thing that wasn't part of physics was mathematics. Of course the word “physics” wasn't in use then, the earliest recorded use of the term is in 1589 according to the Oxford English Dictionary. The OED even mentions that as late as the time of Locke in the 1600's things that we now consider parts of theology such as the study of angels, God, and spirits belonged to physics.

Also according to the OED, the study of organic things (biology, ecology, etc.) split off from physics in the 18^th century, and chemistry split off a little later. This is process continues as fields of study mature and they develop into full fledged disciplines of their own separate from physics. Optics is one such field that is slowly in the process of breaking away from physics. Because of the ambiguity associated with the term, most modern researchers would not dispute that Alhazen's contributions to optics can be considered contributions to physics, especially in the broad sense of the term physics. Rainbows are today considered part of optics. The study of the eye would today be considered anatomy, another scientific field not separate from physics in Alhazen's day.

One final note: astrology is certainly not astrophysics in any sense. In fact, astrology is not science at all. Many scientists of note in history dabbled in astrology because their funding from various monarchs would be cut off if they did not pursue such studies, however, astrology is not a scientific pursuit.