This presentation briefly throws light on a great muslim scientist Al-Hassan Ibn Al-Haytham. Topics discussed are his major inventions, discoveries, books and one of his life events. And Of course, it is only a page from the life of the Scientist, but it will give you a little bit insight in Ibn Al Haytham's work.

1. Al-Hasan Ibn Al-Haytham
“If learning the truth is the
scientist’s goal… then he must
make himself the enemy of all
that he reads. ”
-Al-Hasan Ibn Al-Haytham
“It is incredible that we are only
now uncovering the debt that
today's physicists owe to an Arab
who lived 1,000 years ago”
-Prof Jim Al-Khalili

2. IBN AL-HAYTHAM
Known in the West as Alhazen, Al-Hasan Ibn Al-
Haytham was born during the reign of Buyid Empire at
the time of Adud AlDawla. It was the golden age of the
Muslims. In an area that spread from Spain to China,
inspirational men and women, were making discoveries
that had a huge and often underappreciated impact on our
world. It was the time of Al Hakim Nishapuri, the
Mujaddid of 4th century AH. It was the time of Ibn Al
Haytham, when Al Berouni discovered the radius of the
earth and Ibn Sahl discovered the law of
refraction(Snell’s Law).
(965 in Basra - d. 1039 in Cairo )

3. Ibn Al-Haytham growing up learning, and getting
inspired by all these great personalities and
discoveries, was the first to prove his theories by
experiments. Due to this approach he is known as
the “Father of Modern Scientific Method”[1].
Apart from that, many consider him as the “Father
of Modern Optics” too due to one of his
influential books the “Kitab ul Manaazir” or the
“Book of Optics”. The story of this is rather
dramatic. He is known to have said, “If I would be
given the chance, I would implement a solution to
regulate the Nile flooding”.
[1] But it is often still claimed that the modern scientific method
was not established until the early 17th Century by Francis Bacon
and Rene Descartes.

4. This claim reached al-Hakim, the Fatimid caliph in Egypt who invited him to Cairo.
Confident of his own abilities, Ibn Al Haytham traveled from Basra, Iraq all the way to
Cairo, Egypt.

5. Ibn al-Haytham boasted
that he would tame the
great Nile River by
building a dam and
reservoir. But when he saw
the extent of the challenge
and the marvelous remains
of ancient Egypt on the
river banks, he
reconsidered his own plan.
If such a huge project
could be done, he
reasoned, it would have
been done by the brilliant
builders of the past who had left us such fantastic architectural relics. He returned to Cairo to
inform the caliph that his solution was not possible.

6. Knowing that that particular caliph did not
entertain failure and that his life would be at risk if
he were to disappoint him, Ibn al-Haytham feigned
madness to avoid the caliphs’ wrath. Despite the
caliph’s wild swings of mood, rather than
executing or expelling Ibn al-Haytham from Cairo,
the caliph decided to put the scholar under
permanent protective custody. That was required
by law in order to ensure his safety and that of
others.
Ibn al-Haytham was placed under what amounted to house arrest, far from the lively discourses
and debates to which he was accustomed. Legend says, one day he saw light shining through a
tiny pinhole into his darkened room – projecting an image of the world outside onto the
opposite wall. Ibn al-Haytham realized that he was seeing images of objects outside that were
lit by the Sun. This is the beginning of his discovery for which he is most remembered.

7. Two major theories on vision prevailed in classical antiquity.
The first theory, the Emission theory, was supported by such
thinkers as Euclid(323-283 B.C.) and Ptolemy(90-168), who
believed that sight worked by the eye emitting rays of light.
The second theory, the Intromission theory supported by
Aristotle(384-322 B.C.) and his followers, had physical forms
entering the eye from an object.
But the restricted Ibn Al Haytham in that dark room, from
repeated experiments, concluded that light rays travel in straight
lines, and that vision is accomplished when these rays pass into
our eyes. He transformed his room to an experimental tool.
After many additional experiments using special apparatus of lenses and mirrors which he
built, he laid down his new ideas about light and vision in his Seven Volumes Book of
Optics. He was released from prison on the death of the caliph.
Apart from this, today the oldest-known drawing of the nervous system is from Ibn al-
Haytham’s Book of Optics, in which the eyes and optic nerves are illustrated.

8. He realized that the senses were prone to error (i.e. Optical Illusions), and he devised
methods of verification, testing and experimentation.
Among Ibn al-Haytham’s other insights was his understanding of the crucial role of
visual contrast. For example, he realized the color of an object depends on the color of
the surroundings, and that a contrast of brightness levels explains why we can’t see the
stars during daytime.
From his dark room experiments, he made the
world’s first “Camera Obscura” which literally
means “Dark Room”. It is also known as
pinhole camera.
In his book Kitaab ul Manaazir, he gave the
experimental proof of every theory he had
written.

9. Alhazen offered an explanation of the
Moon illusion, which causes the Moon to
appear larger near the horizon than it
does higher up in the sky. He said that
judging the distance of an object depends
on there being an uninterrupted sequence
of intervening bodies between the object
and the observer. When the Moon is high
in the sky there are no intervening
objects, so the Moon appears close. The perceived size of an object of constant
angular size varies with its perceived distance. Therefore, the Moon appears closer
and smaller high in the sky, and further and larger on the horizon.
Alhazen's Risala fi’l-makan (Treatise on Place) discussed theories on the motion of
a body. He maintained that a body moves perpetually unless an external force stops
it or changes its direction of motion.

10. varying disciplines. According to medieval biographers, Ibn al-Haytham wrote more than
200 works on a wide range of subjects, of which at least 96 of his scientific works are
known. Most of his works are now lost, but about 50 of them have survived to some
extent. Nearly half of his surviving works are on Mathematics, 23 of them are on
Astronomy, and 14 of them are on Optics, with a few on other subjects.
Among his students were Sorkhab (Sohrab), a Persian from Semnan who was his student
for over three years and Abu Al Wafa Mubashir ibn Fatek , an Egyptian prince who learned
mathematics from Ibn Al Haytham.
Alhazen continued to live in Cairo, in the
neighborhood of the famous University of Al-
Azhar, earned his living authoring various
treatises and tutoring members of the nobilities,
until his death in 1040 AD. Apart from all this,
Ibn al-Haytham was a pioneer in many areas of
science, making significant contributions in