Abu Ali Hasan Ibn al-Haitham. Also known as 'Alhazen'
In Al-Haitham's writings, one finds a clear Al-Haitham's 'Opticae
Thesaurus.'
His work also influenced Leonardo da Vinci and Johann Kepler. In
Physics, he studied the mechanics of motion of a body and was the first
to propose that a body moves perpetually at constant velocity and in a
straight line unless an external force stops it or changes its direction
of motion. This is strikingly similar to the first law of motion. It is
also a startlingly counter-intuitive insight: we never see this happen
on earth.
The ideas contained in his book on evolution are worth reading and
useful even today. He wrote commentaries on Aristotle, Galen, Euclid and
Ptolemy. Indeed, he contradicted Ptolemy's and Euclid's theory of vision
that objects are seen by rays of light emanating from the eyes;
according to him the rays originate in the object of vision and not in
the eye.
ALHAZEN'S BILLIARD PROBLEM
In 1997, Alhazen's name was briefly in the news. He had worked
extensively on a problem formulated by Ptolemy in A.D. 150. Alhazen
wrestled so hard with it that it became known as 'Alhazen's Problem', or
even 'Alhazen's billiard problem, because the questions it deals with
can apply to billiard balls as well as spherical mirrors. It was not
solved until more than a thousand years after Alhazen's death, by an
Oxford don in 1997.
It was known as 'the last great problem of classical geometry', and for
Alhazen it could be posed in this way. Given a light source and a
spherical mirror, find the point on the mirror where the light will be
reflected to the eye of an observer.
Adapted to become "Alhazen's Billiards Problem", it may also be
formulated in this way: How does one find the point on the boundary of a
circular billiards table at which the cue ball must be aimed, if it is
to hit the cushion and then the black ball? Dr. Peter Neumann, a fellow
of Queen's College, Oxford cracked this riddle, which had baffled
mathematicians for a millennium. The great difficulty in the problem lay
in the fact that mathematicians envisage spherical mirrors or billiard
balls as infinitely small points. Classical ruler-and-compass methods
developed by Euclid, the Greek mathematician, were not helpful in this
case. They did not provide the means to derive a cube root. Neumann
translated the billiards table geometry into co-ordinates on two axes.
These may be called X and Y. It was an insight