Theory of optics by Ibn al-Haytham

The Optics of Ibn al-Haytham consists of seven books. It deals with the theory of vision; theory of perception: visual deception; the laws of reflection, mathematical problems concerning refection in mirrors; errors of vision due to reflection; and refraction.

Ibn al-Haytham’s object in the Book of Optics is: to achieve a synthesis between the geometrical optics of Ptolemy and Euclid and the traditions of natural philosophy, including the Aristotelian tradition.

Book of Optics was a real science textbook, with detailed descriptions of experiment, including the apparatus and the way it was set up, the measurements taken and the results.

These were then used to justify his theories which he developed using mathematical models.

Kitāb al-Manāẓir

Ibn al-Haytham rejects the Euclidean and Ptolemaic doctrine of a ray stemming out from the eye, called a visual ray, in order to defend the intromissionist theory of visible forms.

Ibn a-Haytham says that ‘forms’ of light propagate from any point on the luminous object in all directions. Ibn al-Haytham proves that the incident and reflected ray are coplanar with the normal to the mirror through the point of refection and make equal angles with the normal.

In the Book of Optics he devotes the first three chapters to the foundations of this theory. In the three following chapters, he deals with catoptrics.

The Book of Optics was translated into Latin around 1200, and the first printed edition by F. Risner appeared in 1572.

The work was studied by many notable European scientists, such as Witelo, Roger Bacon, Leonardo da Vinci, Kepler and Descartes. Ibn al-Haytham was aware of the structure of the eye from the view point of a physician as well as a physicist.

Equally importantly, later Islamic scholars would make great used of his work and extend it further, such as the Persian al-Shirazi and al-Farisi in the thirteenth century ,the latter using it for the very first correct mathematical, explanation of the rainbow.

Many of anatomical names of the various parts of the eye that are used today are translations from the names given by Ibn la-Haytham in his Book of Optics.
Theory of optics by Ibn al-Haytham

Measles in history

Measles probably began with the start of urban life in the Middle East around 3000 BC.

Some historians believe that a plague that killed a large part of the Athenian army in 430 to 429 BC was measles. As urbanization occurred in subsequent centuries, the proximity or larger populations nurtured epidemics with continued circulation of virus in cities. There were massive epidemics in the Roman Empire starting in 165 and in 251 AD, and two similar epidemics in China in 162 and 310.

Jews physician such as Al Yehudi had recognized the illness but without distinction between it and other rash disordered.

Measles was first documented by an Arabic physician called Rhazes.

Rhazes lived in the 10th century but he quoted other authors on measles form as far back s Al Yehudi, who lived in the 7th century.

He distinguished between smallpox and measles even though he believed that the two conditions were part of one morbid process.

Rhazes referred it the disease as widespread throughout the East and the same opinion is expressed by Avicenna and other Arabic writers of the tenth and eleventh centuries.

By the 17th century, some European also physicians had identified the differences between measles and small pox.

In 1846, a Danish physician Peter Panum studied a measles outbreak on the Faroe Islands and was the first to describe the clinical presentation, incubation and infectious nature of measles.

The introduction of measles vaccine in 1963 and its subsequent widespread use led to dramatic declines in the reported incidence of measles.
Measles in history

Al-Kindi (801–873 CE)

Al-Kindi or Abu Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī was a Muslim Arab philosopher, polymath, mathematician, physician and musician. He was known as Al-Kindus by Western world.

Al-Kindi began his education at either Kufah or Basra, and completed it at Baghdad the centers of culture of his day.

Both Kufah and Basra were places of intense and original intellectual activity by the tome of Al-Kindi’s birth; this activity centered on a number of disciplines indigenous to Islamic culture such as Arabic grammar, the explication of the Qur'an and the principles of law, all of which would have important consequences for philosophy.

He studied Fiqh and the new born discipline called, kalam, but it seems that he was more interested in science and philosophy, to which he unsecrated the rest of his life, especially after he went to Baghdad.

Al-Kindi learnt Greek, but certainly he mastered the syriac language from which he translated several works.

He became well known in the Abbasid capital as a scholar and physician, enjoyed the patronage of the caliphs al Ma’mun and al-Mu’tasim and was appointed tutor of the latter’s son Ahmad.

Al-Kindi wrote hundred of papers on Greek philosophy, science, ethics, cosmology, metaphysics and what is known today as psychology, from an Islamic perspective.

He is a major contributor to the introduction of Greek philosophy to the Muslim World, although he was not afraid to contradict the Greek thinkers if he believed it conflicted with Islamic teachings.

Al-Kindi died on 873 in Baghdad, Iraq.
Al-Kindi (801–873 CE)

Ibn al-Haytham's Book of Optics

Book of Optics (Kitāb al-Manāẓir‎  in Arabic) was written in 1021 by Ibn al-Haytham in 1021. The book was first use of controlled experiments and reproducibility of its results.

The Book was translated into Latin around 1200. It was first printed in Latin in 1572 under the title Opticae Thesaurus Alhazeni Arabis Libri Septum by F. Risner.

Ibn al-Haytham was born in Basra in about 965 AD and died in Cairo in about 1040, In his autobiography he lists ninety-two of his own works, more than sixty of which have survive.

Ibn al-Haytham work reveals not only its revolutionary nature but also its comprehensiveness, touching all the known branches of optics.

The Optics of Ibn al-Haytham is the first authoritative work opposing the theory of Euclid, Ptolemy and other ancients that eye sends out rays of light and impinges on external things to view objects.

Ibn al-Haytham firmly rejected the emanation theory of vision and described how rays of light enters the eye from sources of light and from objects that reflects and refract light.

Ibn Haytham’s legacy in optics left a profound impression in the works of medieval scholars including Roger Bacon, John Pecham and Witelo and found conceptual prolongations an creative applications in the works of Renaissance artist and theorist such as Leon Battista Alberti, Lorenzo Ghiberti and Egnazio Danti.

Ibn-Haytham was aware of the structure of the eye form the view point of a physician as well as a physicist. Many anatomical names of the various parts of the eye that are used today are translations from the Arabic names given by Ibn al-Haytham in his Book of Optics.
Ibn al-Haytham's Book of Optics

Book of Ingenious Devices (Kitab al-Hiyal)

The Book of Ingenious Devices (Kitab al-Hiyal) published in 850 by the three Iranian brothers known as the Banu Musa.

The Banu Musa or sons of Musa were among the most important figures in the intellectuals and political life of ninth century Baghdad and played a key role in the founding and devilment of Arabic science and technology.

Three brothers were called, Muhammad, Ahmad and al-Hassan. They were working at the House of Wisdom (Bayt al-Hikma) in Baghdad, Iraq, under the Abbasid Caliphate.

The brothers were interested in geometry, mechanics, dynamics, music and astronomy and also that in order to study scientific works of classical times, they employed the service of team of translators.

The book was a large illustrated work on mechanical devices that included automata, puzzles and magic tricks.

On of the most impressive devices described in the book is also possibly the earliest example of a programmable machine: a robotic flute player.

In Book of Ingenious Devices, Ahmad described a contraption that would deliver hot and cold water, devices for digging wells and a lamp with a self-trimming wick.

The book is a document of some social significance, because it witnesses to the degree of mechanical knowledge and understanding of early Abbasid times,
Book of Ingenious Devices (Kitab al-Hiyal)

Ibn Ishaq Al-Tunisi (1193-1222)

In al-Andalus and the Maghreb, various astronomers continued producing zijat (planetary tables) in the tradition of Azarqueil , introducing new parameters, giving new presentation to old tables, and compiling new ones, but hardly deviating from the essential features established by their predecessors.

Among the astronomers was Ibn Ishaq Al-Tunisi.

According to Ibn Khaldun in his Muqaddima, Abul Abbas Ahmad ibn Ali ibn Ishaq al-Tamimi al-Tunisi was a Tunisian astronomer of the early thirteenth century.

He compiled an impressive astronomical handbook with tables.

It contains an important set of tables which mark the starting point of a Maghribian astronomical school. The unfinished set of tables by Ibn Ishaq survived in a unique manuscript of Hyderabad, discovered in 19878 by David. A. King.

The predominant influence in Ibn Ishaq tables was that of the Andalusia school represented by Ibn-Zarqalluh, Ibn al-Kammad and Ibn al-Haim.
Ibn Ishaq Al-Tunisi (1193-1222)