There have always been two kinds of physics – speculative and experimental. Since the scientific revolution in seventeenth-century Europe the two approaches have tended to converge, and to become complementary to each other. In the Middle Ages, however, because of the immense authority of Aristotle, the speculative approach was the more highly regarded among scholars. Although Aristotle used the experimental technique of dissection to extend the range of his observation of animals, in physics he adopted an approach in which speculation reigned unchallenged and observation played a negligible role. Those who followed this path in the Middle Ages – for example Ibn Sīnā and Ibn Rushd in Islam, St Thomas Aquinas in Latin Christendom – attempted to reconcile Aristotle's views with theological and cosmological dogmas. Such philosophers might on occasions hold widely different views from Aristotle's, but their differences were based upon logical and theoretical grounds, not upon observation and experiment. Reverence for the authority of Aristotle was such that his influence had a stultifying effect upon creative thought. The freeing of scientific thought from Aristotelian bonds was to prove an immensely difficult task for scientists over many hundreds of years. Nevertheless, in the Islamic world there were a number of great scientists who did take the experimental path, and in doing so achieved highly significant results in physical investigations.

The students of the physical sciences in Islam were far fewer than the students of mathematics, astronomy, alchemy and medicine. Of the subjects usually considered as constituting the substance of classical physics – electricity and magnetism, heat, sound, optics, solid and fluid mechanics – only the last two were given much attention by Arabic writers. In the fields of statics and optics, however, the Islamic contribution was very important, and can best be appreciated by a consideration of the achievements of a few great scientists. Before doing this, we shall discuss briefly the work done on other subjects, where there is anything of significance to report.