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Physics & Optics
 Physics
is the science of motion and its laws, but also of sound,
and light, and discussion of matter and energy. The modern
science of physics grew out of many Medieval disciplines,
ranging from philosophy, or speculative thought, to music
theory, engineering, and optics -- the study of light and
vision, including mirrors, lenses, rainbows, shadows and the
process of seeing. Experiments in flight and projection of
objects in space (such as cannons, catapults and gliders)
are also considered part of physics.
Achievements in Islamic Spain include new ideas produced by
studies of physical science that were then published in
books, and also translations of works from other Muslim
lands, that were transferred to Europe and beyond. They
include applications of physics to practical life in areas
such as use of energy and hydraulic technologies.
Achievements in the physical sciences began at the court of
Córdoba during the 9th and 10th
centuries CE, where artists and scholars, inventors and
writers could find patronage and interest in their ideas.
Books from the eastern Muslim lands, especially Baghdad,
were eagerly collected in Andalusian libraries of half a
million volumes.
Among
the works brought there were al-Khwarizmi’s mathematical
writings. Like most other scholars of the time, al-Khwarizmi
experimented with many ideas, such as calculating the
thickness of earth’s atmosphere, and problems with optics,
such as magnification. Works on sound and music theory were
well known and put to practical use in building complex
musical instruments.
 Ibn al-Haytham
(died ca. 1040 CE), known in Latin translation as Alhazen,
was a scholar in Cairo whose work was widely translated into
Latin during the 12th century CE and is still
studied by historians of science today. Ibn al-Haytham
described his experiments and investigations about light and
vision in an innovative work called
The Book of Optics. He analyzed the structure of
the human eye and described how it sees. He overturned
theories held since Aristotle and Ptolemy that either the
eye sent out rays that allowed objects to be seen, or
objects sent some force toward the eye.
Ibn al-Haytham
demonstrated how light enters the eye through the pupil.
Using mathematical formulas, he described how light falling
on the eye is refracted through its lens, allowing the eye
to sense forms of light and color, and the mind to perceive
and order the images. Other optical experiments and
investigations included projecting the sun’s image on a wall
through a small opening, which is the
camera obscura similar to early photographic
cameras of later centuries. (The light-sensitive film to
capture the image was a much later invention.)
He
investigated mirror theory, described spherical and
parabolic
mirrors, calculated how light is refracted (bent), and how
light passing through a lens is broken into the color
spectrum -- the rainbow. His investigation of glass and
water lenses led to the creation of mathematical formulas
that allowed advancements in refining the shape
of lenses. European scholars studied these ideas, which led
to lenses for telescopes, magnifying lenses, and eyeglasses.
 Most
surprisingly, his mathematical discussions of the way the
eye sees led to the development of perspective drawing, a
major aid to realistic painting, but also a great
advancement in accurate illustration for scientific and
technical books. Combined with the invention of printing,
perspective drawing allowed accurate transmission of ideas
for machines, architecture and other fields. Ibn Al-Haytham
influenced important scientists such as Witelo, Kepler, and
Roger Bacon, making Alhazen the most quoted physicist of the
Medieval period.
Although the achievements of Ibn al-Haytham, like those of
other Muslim scientists, have been neglected, a 17th
century engraving in a scientific book shows Galileo,
inventor of the telescope and astronomer, dressed as an Arab
and posing opposite him as a tribute to his contribution.
Other
applications of physics were being used and developed in Al-Andalus.
In hydraulic technology, machines to move water were built
on models like those of al-Jazari, who invented the
crank-connecting rod system. This was very important to the
development of technology, because it involves a way of
transforming rotation into linear motion, like the mechanism
that moves your bicycle. The same principle is used in car
engines.
Al-Jazari’s
manuscript is full of innovations, such as valves and
pistons, one of the first mechanical clocks driven by water
and weights, and a combination lock. Andalusian Muslim
engineers continued to produce and perfect mechanical
clocks, and this knowledge was transmitted to Europe through
Latin translations of their books on mechanics. Many of
these books have since been lost or destroyed.
Another
practical and experimental scientist who worked in Al-Andalus
was as Abbas ibn Firnas (810–887 CE), who came to Córdoba
from Baghdad to teach music theory at the court of Abd
al-Rahman III. Ibn Firnas worked in many fields, including
chemistry, physics, astronomy, and as a poet. He designed a
water clock, he worked to improve the way glass was made,
and is said to have worked on eyeglasses to help those with
poor vision. He devised a way to cut very hard quartz, or
rock crystal, and made a mechanical model to show the
motions of planets and stars.
 In 875
CE, Ibn Firnas did something that made him famous, but
almost ended his career. He constructed a glider, and
launched himself into the air. The flight was successful,
and was viewed by a crowd of invited guests. As an
experimental vehicle, however, the design was not perfected,
and it had no tail to help with landing, a fact which he
later noted when observing birds. He injured his back upon
landing. Historian Philip Hitti wrote, “Ibn Firnas was the
first man in history to make a scientific attempt at
flying.” A crater on the map of the moon is named Ibn
Firnas to honor his achievement as one of the first
people to fly.
Europeans benefited greatly from the knowledge and research
of Muslims in physics. One proof of this is that many these
books were translated into Latin in Spain. Another proof is
that these books were taught in European universities and
quoted by scientists as they developed their own work.
Finally, they were among the first books printed after
Gutenberg invented the printing press in 1453 CE by, and
were re-printed many times. These ideas laid the foundation
for the Scientific Revolution of the 16th and 17th
centuries CE. Even though much of this Muslim legacy was
forgotten, historians of science are restoring its rightful
place today.
Further Reading:
Jan P. Hogendijk and A.I. Sabra,
editors.
The Enterprise of Science in Islam. Cambridge,
2003. Retrieved at
http://www.ais.org/~bsb/Herald/Previous/95/science.html
John H. Lienhard.
Engines of Our Ingenuity. Radio episodes
online retrieved at
http://www.uh.edu/engines/engines.htm, see episode #999
at
http://www.uh.edu/engines/epi999.htm
Ibn al-Haytham.
Scientists and Discovery
Series. Museum Victoria, Australia,
retrieved at
http://www.museum.vic.gov.au/scidiscovery/scientists/al_haytham.asp
Abdelhamid I. Sabra, professor emeritus of the history of
Arabic science. Ibn al-Haytham.
Harvard Magazine Sept.-Oct. 2003. Retrieved
at
www.harvardmagazine.com/on-line/090351.html
Images:
Abbas Ibn Firnas, 875 CE attempt at
flight image from
The Islamic Times, November 1998, retrieved at
http://www.angelfire.com/realm/bodhisattva/flyers.html
Anatomy of the eye from
Kitab al-Manazir, Museum Victoria, Australia,
retrieved at
http://www.museum.vic.gov.au/scidiscovery/image_pages/mn006557.asp?
URL=http://www.museum.vic.gov.au/scidiscovery/scientists/al_haytham.asp
Engraving from 1647 book showing Galileo and Alhazen, with
drawings of mathematical solutions to problems concerning
refraction and lenses from
Kitab al-Manazir retrieved at
www.harvardmagazine.com/on-line/090351.html
Model of Ibn Firnas’ glider at 1001
Inventions virtual exhibition, retrieved at
http://www.1001inventions.com/img/site_020/abbas.jpg
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