Analysis of information sources in references of the Wikipedia article "History of physics" in English language version.
The same holds for Alhacen's methodology. It may look modern because of its strong empirical bias and reliance on controlled experiments, but Ptolemy's approach was no less empirical, and it, too, was based on controlled experiments. In addition, Alhacen's two most modern-looking experiments are based on physically unobtainable precision in equipment design and observation, so we are left to doubt that he actually carried them out as described— except, of course, in his mind. And these experiments were not new in conception. They were clearly based on equivalent ones in Ptolemy's Optics, although Alhacen had to reformulate them in significant and creative ways to accommodate the testing of light rays rather than visual rays.
