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Home > Dictionary of Science Quotations > Scientist Names Index A > Alhazan Quotes

 Alhazan (c. 965 - c. 1040) Arab philosopher and physicist (also known as Abu ‘Ali Al-Hasan ibn Al-Haytham, Ibn al-Haitham, Ibn al-Haytham, Al Hazan or Alhazen) who as a great Arab experimentalist was a pioneer of optical science. In his seven-volume work, Optics, identified that vision resulted from illuminating rays reaching the eye (whereas ancient Greek scientists had long held that the eye originated the rays).

Science Quotes by Alhazan (1 quote)

The sun’s rays proceed from the sun along straight lines and are reflected from every polished object at equal angles, i.e. the reflected ray subtends, together with the line tangential to the polished object which is in the plane of the reflected ray, two equal angles. Hence it follows that the ray reflected from the spherical surface, together with the circumference of the circle which is in the plane of the ray, subtends two equal angles. From this it also follows that the reflected ray, together with the diameter of the circle, subtends two equal angles. And every ray which is reflected from a polished object to a point produces a certain heating at that point, so that if numerous rays are collected at one point, the heating at that point is multiplied: and if the number of rays increases, the effect of the heat increases accordingly.
— Alhazan
In H.J.J. Winter, 'A Discourse of the Concave Spherical Mirror by Ibn Al-Haitham', Journal of the Royal Asiatic Society of Bengal, 1950, 16, 2.
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In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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