How can animals in the wild hunt during the night as if it were day? A remarkable biological feature acts as a pair of “natural” night vision goggles.

Animals can move and even hunt in the pitch-dark of the night. How do these animals see comfortably in the dark? How are their eyes different from ours?

Anatomically, the eye consists of three layers called the Tunica fibrosa (outer layer), the Tunica vasculosa (mid layer), and the Tunica nervosa (retina). The outer layer of the eye is composed of the sclera and cornea; the middle section of choroidea, corpus ciliare, and the iris; and the inner section of the retina.

Light rays reflected off objects first pass through the eye’s translucent layer (the cornea), then into the black round part located in the front of the eye (pupillae, or pupil), and later go through the lenses. The colored section around the pupil, covered by smooth muscles, is in charge of regulating the amount of light entering the eye. The real and inverted image of an object is projected on the retina by the refraction of light through the lens; the image is transmitted to the optical center of the brain as a result of nerve cell stimulation via the optical nerves. Sight happens as a result of these causal chains.

Now, there is a twist to all this: the optical center in the brain accepts spots that do not emit light as black. For humans, this means a loss of sight. Black objects are not visible because they absorb and keep all the light reaching them.

How could these animals, without night vision goggles, see in pitch blackness despite having the same optical mechanisms as humans?

The answer to this question was hidden in an anatomic structure (tapetum lucidum) located in the eyes of some vertebrates. This special structure, lacking in humans, monkeys, squirrels, birds, red kangaroos, and some other mammals, is found in equines, ruminants, and many carnivores. This structure is located in the cytoplasm of the choroidea layers in between the innermost light sensitive ocular layer and sclera, and it acts like a biological reflector. With its crystalline composition of varying colors from golden yellow to white, tapetum lucidum is a wonder of creation. The eyes of these animals shine when a light source is projected due to the aforementioned structure.

The primary task of this formation is to reflect the light which is projected to the rear section of the eye again without absorbing it. This happens due to the crystalline makeup. Thus, lower light levels are enhanced by the repeated reflection in the eye, and sight is enabled for animals. The second job of Tapetum lucidum is to elevate the sensitivity of the retina to light in order to transmit signals with no stimulation strength to the optical center.

This reminds us of night vision goggles. Night vision cameras are electro-optical devices that strengthen the light that is present. Light enters this device through the lens and hits the charged cathode, which has a lot of high energy. The energy load hits the phosphorous screen where the image is focused after passing through the vacuum inside the charger. The image is an enhanced picture on the phosphorous screen and it is not visible directly through the object. Tapetum lucidum however, is such an artistic work that it cannot even be compared with the night vision systems of technology. While the lifespan of a night vision system is only 2,500–4,000 hours (104–167 days), animals with Tapetum lucidum can benefit from this for a lifetime. The newest night vision systems, with a maximum optic range of 30-120 meters, cannot provide sight under light conditions one fourth of the moon’s illumination strength, whereas animals with Tapetum lucidum can see objects hundreds of meters away in much dimmer light.

This isn’t the only example of how masterfully and diverse eyes can be. Damseflies have over 30,000 simple eyes, called ommatids; eagles can see their prey from thousands of feet above them.

By the principle that “certain things are appreciated best in their absence,” if we imagine a dark night in which we are unable to see anything and cannot even step a foot safely, we can perhaps understand that Tapetum lucidum is a great blessing for these animals.

Reference

Veterinary Ophthalmology (2004) 7, 1,11–22. Comparative morphology of the tapetum lucidum (among selected species), F. J. Ollivier,* D. A. Samuelson, D. E. Brooks, P. A.Lewis, M. E. Kallberg and A. M. Komáromy.

Finkelstein S.L et al., Nature, October 2013

Astronomers have recently spotted a faint ray of light using the Hubble Space Telescope, a ten-meter telescope at Keck Observatory, located at the summit of Mauna Kea, a dormant volcano in Hawaii. Analysis of light showed that it was a galaxy formed 13.1 billion years ago, which is only 700 million years after the Big Bang, when our universe came into existence. This is so far back in time, it would be about 8 billion years before our sun was born. The new galaxy is called z8_GND_5296, and it is the oldest and most distant galaxy ever discovered. Because the universe is expanding, the lights coming from distant objects would be stretched, and their wavelengths changed, as they travel through the expanding universe. This phenomenon is called Redshift. It makes visible light look redder, and redshift increases proportionally with the distance to an object. Lights coming from z8_GND_5296 looked more redshifted than anyone had seen before. More detailed analyses showed that the mass of gz8_GND_5296’s stars was equivalent to 1 billion suns, which is approximately 50 times less than the Milky Way’s stellar mass. Even more surprisingly, the new galaxy is found to have an unusually high star-formation rate. This rate is typically calculated by how much raw hydrogen the galaxy yearly converts into new stars. gz8_GND_5296 converts hydrogen 300 times the mass of our sun, while the Milky Way produces 1 or 2 solar masses per year. One of the explanations for this extraordinary star-formation rate is that the early galaxies contained or drew in much more gas than scientists expected. The search for distant galaxies aims to find the very first galaxies formed after the Big Bang, perhaps the ones that produced the first natural elements. To this end, NASA plans to launch the James Webb Space Telescope (JWST) in 2018. JWST will reside in an orbit 1.5 million km from the earth and hopefully it will help astronomers to look further and further back into the origins of the Milky Way, and ultimately, the history of our universe.

Vast Freshwater Reserves Found Under Ocean

Offshore fresh groundwater reserves as a global phenomenon.
Post V.E.A et al., Nature, December 2013

As earth’s population rises, we face a serious problem of fresh water supplies. The United Nations predicts that half of the world will be struggling to find clean, fresh sources of water by 2030. Luckily, Australian scientists discovered huge freshwater reserves, and in the most unexpected place: under the ocean floor. Newly discovered reserves are estimated to contain 500,000 cubic kilometers of low-salinity water, located off the coast of South Africa, North America, Australia, and China. This vast reserve is approximately 100 times greater than the volume of the fresh water used since the beginning of the 1900s. This water reserve is thought to develop earlier in Earth’s history, perhaps over thousands of years, when oceans were not that deep and when the coastline was further out. Scientists hypothesize that rainwater leaked through the ground and had created these fresh water aquifers beneath layers of porous rock and/or soil. Around 20,000 years ago, the polar ice caps began to melt and these regions were covered by ocean. Fortunately, layers of either clay or sediment seemed to protect the reservoirs from salty contamination: the salinity of this water is low enough to be readily transformed into drinkable water. These water reserves can be extracted by constructing drilling platforms, either at sea or from the mainland, close to aquifers. However, drilling projects are usually very controversial due to environmental and economic costs. Scientists are currently seeking alternative, more environment-friendly ways to use these reserves. Nonetheless, mankind may have found a new vital water resource for the future.

Crows Don’t Forget a Face; Crow Intelligence Decoded

Abstract rule neurons in the endbrain support intelligent behavior in corvid songbirds.
Veit L. and Nieder A., Nature Communications November 2013

Scientists have long suspected that members of the corvids – a family of birds that includes ravens, crows and magpies – are extraordinarily intelligent. They make and use tools, remember multiple feeding locations, and exhibit highly social behaviors. Last year, scientists even demonstrated that crows captured in Seattle would never forget the face of their abductor and they would still taunt and dive-bomb the threatening face several years after the incident. To understand the mechanism of crows’ amazing face recognition process, neurobiologists designed an experiment, in which they trained the crows to perform memory tests on a computer. The crows were first shown an image and shortly afterwards, they had to select one of two test images on a touchscreen, using their beaks, based on switching behavioral rules. One of the test images was identical to the first image; the other one was a different image. Sometimes, the rule of the game was to select the very same image, and sometimes it was to select a different one. Remarkably, the crows were able to carry out both tasks and to switch between them almost perfectly. These tasks require a high level of concentration and mental flexibility that few animal species can manage – they even require a great effort for humans. By recording single-unit neuronal activity from an association area of the crow’s brain, known as the nidopallium caudolaterale (NCL), the researchers were often able to guess which rule the crow was following, even before the crow made its choice. The cerebral cortex in human brain is very large and it is thought to be home to complex cognitive functions including face recognition. However, since a bird’s cerebral cortex is much smaller than humans, people long thought that birds could not perform intelligent tasks. This study shows that birds use a unique non-cortical brain region, nidopallium caudolaterale (NCL), to sort sensory information and decide how to react.

For many, math is the most difficult class. Is it because of our own laziness, or is much math too abstract to comprehend? Ali Unver says, “educators who see the beauty at the center of mathematics and can make their students see it that way, are more likely to be able to get their students’ attention and teach them more effectively.” He explains in “Mathematics and the Universe” that mathematics is not only for keeping track of our checkbooks.

Mary and Jesus, peace be upon them, are the subject of a considerable amount of Islamic literature. Ahmet Cetinkaya contributes with a thesis on the question of whether Jesus had any brothers and sisters. Drawing on sources of Islamic tradition and the Bible, Cetinkaya lays out interesting information on the topic, which is also a matter of debate between some Christian denominations.

“Romania – Dar-ul Sulk” discusses how historical truths are sometimes forsaken for the sake of political interests. Victor Nitelea presents an exemplary account of the mutually beneficial centuries-long relationship between the Ottomans and Romania and how the positive image of Turks as a tolerant society was replaced by an image of barbarians. This account also explains how the school curriculum can be manipulated according to political trends at the expense of causing intolerance and conflict between East and West.

“Can I Be Your Baggage?” Barney Zwartz, a journalist from Melbourne asks Abdullah Aymaz, who spoke about the emergence of the Gulen Movement in an international conference organized by the Australian Catholic University back in July. Whose baggage did he want to be? Zwartz was referring to the educational movement started in the 1960s among a small circle of young people like Mr. Aymaz who were inspired by Fethullah Gulen. In this issue, Aymaz shares with us his observations of the conference with some flashbacks to his first encounters with Mr. Gulen and how the movement started to take shape.

It is our observation that the popular image in Romania of the Turk as an enemy is a late, nineteenth-century acquisition, triggered by the political motives of contending Romanian groups at the time, and it has rolled on ever since with no real justification in “third-form History,” including in school textbooks. For the first four hundred years or so of common, close ties in Romanian–Turkish history there is no serious indication leading us to think that the Turk’s image was the image of the “enemy” for Romanians as a whole. The Turk’s image, as it emerges from the chronicles of the time, is essentially based on religious difference-he is “the Pagan,” the believer in a “wrong belief,” just like the Catholic (“the Papist”) or the Mosaic (“the Jew”). The difference in religion does not necessarily entail hostility or enmity.

Things change in the nineteenth century when Moldova and Walachia are disputed by the Russian and the Ottoman empires, to the point that legends of the Moldovan capital of Iasi say that the local princes had a huge double-sided painting with a portrait on one side of the Sultan and on the other side of the Tsar: according to which empire’s troops entered the capital, they would display one side of the painting or the other. This is probably a legend or an exaggeration, but it is illustrative of the political atmosphere in the extra-Carpathian Romanian Principalities, an atmosphere proper for the development of pro-Russian and pro-Ottoman partisan groups-political parties, in all but name. Later, there would also emerge a pro-Western “party.” It was in order to accomplish their immediate and local goals that the anti-Ottoman “parties” forged the image of the Turk as an enemy.

This image was forged against a rather favorable popular image the Turk had gained after centuries of rather tolerant suzerainty. A popular rhyme of the time-still quoted by the national poet Mihai Eminescu late in the second half of the nineteenth century-claimed that “Our affairs would have been prosperous if the Turk was not as he is; a master warrior, but a poor diplomat.” (“Bine ne-ar fi fost în toate, dacă turcul n-ar fi fost / Mester numai la războaie, da-n diplomatică, prost!”). The evaluation, while notably precise-the Ottomans fought bravely and successfully the Tsarist troops in the 1806–1812 war, but made a disadvantageous peace, handing over the eastern part of Moldova to Russia, on account of the betrayal of their grand dragoman, the Greek Nicolae Moruzi-does not lack sympathy and understanding for the Turk. But instead of this Romanian frustration taking an anti-Russian or even anti-Greek form, it took, thanks to “third-form history,” an anti-Turkish form. Like all biases, this one too proved to be self-entertaining, and rolled through the centuries with nothing to fuel it after the 1877 Romanian Independence war, a war of doubtful utility for Romania, in Mihai Eminescu’s opinion (as well as, modestly, in ours), since after the 1829 Adrianopolis peace, the advantages of Turkish suzerainty far outweighed the disadvantages.

But the change for the worse of the Turk’s image as a result of local political interests in the nineteenth century is frustrating to the truth-seeking researcher for reasons lying deeper in history, namely, the fact that the Romanian people owes to a degree the free conservation and development of its identity throughout the late Middle Ages to the full observation by the Turks of the original treaties between the two nations. We shall further develop this subject.

The original peace treaties between the Ottoman Empire and the principalities of Walachia and Moldova-the so-called “old capitulations”-were agreed by the Turks with the greatest princes in the history of these countries: with Mircea the Old for Walachia at the beginning of the fifteenth century, and with stefan the Great for Moldova, at the end of the same century. Both these treaties were agreed after the Romanians had obtained brilliant military victories against the Turks. Therefore, their accepting Turkish suzerainty was considered, according to Islamic principles, as willing surrender, not as surrender obtained by force. Walachia and later Moldova were thus considered “Dar-ul-Sulh,” Lands of Peace. According to the Qur’anic recommendations, such countries received much better treatment than countries conquered by the sword-“Dar-ul-Harb,” or Lands of War. This treatment was inferior only to that received by Muslim countries-“Dar-ul-Islam,” or lands of Islam. While the neighboring peoples-Bulgarians, Serbians, for a short time Hungarians-received the “Dar-ul-Harb” treatment and lost their autonomy, being ruled by Turkish generals, the Romanian principalities of Walachia, Moldova and for a short time Transylvania enjoyed the “Dar-ul-Sulh” treatment.

Practically, this meant three main provisions in the “old capitulations”:

a) the interdiction of Turks’ ownership of land north of the Danube (with the exception of four bridgehead cities-“raia”).

b) the interdiction of religious proselytism by Turks north of the Danube.

c) the political autonomy of the principalities, which were to be ruled by Christian princes.

Later, the “old capitulations” were repeatedly transgressed by the Moldovan and Walachian princes, allowing in principle the Turks to transgress in their turn the three above-mentioned main provisions. However, they felt Qur’an-bound and Islam-bound to continue treating the two principalities as “Dar-ul-Sulh.” It is our opinion that this constancy of the Turks in observing the treaties, namely the three provisions, allowed the Romanians to maintain and develop their national and religious identity during the late Middle Ages in much better conditions than the neighboring peoples.

And it is a pity that this merit of the Turks, and of Islam, does not find its way into “third-form History” textbooks in Romania for presentation to the young.

Died on January 8, 2009, Victor Nitelea was a former expert, Romanian Commission for UNESCO and a leading Romanian journalist.

In memory of a dear friend

Victor Nitelea (April 8th 1952 – January 8th 2009) was my best friend in Romania. He was a unique person in many ways-an intellectual with a vast ability to incorporate sound knowledge and wisdom in politics and history as well as in mathematics and engineering. When he told me that he had written a dissertation on table tennis, I told him that it would not be a surprise if he came out with another thesis on spacecraft.

The Great Stefan told his child with his dying breath, “You can always trust Turks as they never betray you.” Victor had a deep trust in me as his Turkish friend. We had long, delightful discussions. He was a good listener, while his knowledge was enough to be the only speaker in any conversation.

He wrote fourteen books, was columnist on several journals, and appeared regularly on TV shows. He had a beautiful mind and was a popular face in the community. It was very sad hearing the news that he had lung cancer. I could not imagine the coming days without his company. Romania was not only losing an intellectual but also a good believer. Victor was a monotheist, saying that God cannot be associated with partners. He had deep respect for the Prophet Muhammad, peace be upon him.

Before he died, he gave me an article about the relationship between Turks and Romanians. For him, it was because of Turks that Romania still exists as a nation and as a country. Sharing this essay with The Fountain readers is, I hope, a fair treatment of his legacy.

I had the chance to meet him many times. I hope this essays provides an opportunity for The Fountain readers to have a conversation with Mr. Nitelea.

Dr. Ahmet Ecirli, University of Bucharest, Department of Sociology

Human beings are visually-oriented in their daily life; they use the sense of sight more than any of the other senses with which they have been endowed. The modern understanding of human vision and the underlining principles were only discovered in the past couple centuries. The nineteenth and twentieth centuries witnessed the development of photographic and digital imaging camera systems, which partially mimic human visual systems. We will open a small window on the history of human vision and camera systems, and try to compare today’s state-of-the-art cameras with the human visual system, focusing mainly on solid-state image sensors, or camera chips, and the image-sensing element of the human visual system, the eye.

History of human vision

Human vision has been the subject of conflicting interpretations since ancient times. Many ancient physicians and philosophers believed in the theory of extramission, or the active eye. According to this theory, the eye perceives objects by emanating light and seizing objects with its rays. It was in medieval Islamic culture that research on human vision and optics developed into a system similar to the modern theory of vision. Among others, Ibn Al-Haytham (Alhazen) (965-1040 A.D.), a Muslim physicist, astronomer, and mathematician in the tenth century, played a great part in this field by promoting the intromission theory which states that vision only occurs because of light rays entering the eye. Ibn Al-Haytham founded physiological optics, which distinguished the functioning of the eye from the behavior of light. On the other hand, ten centuries after Ibn Al-Haytham, Winer et al. (2002) have found recent evidence that as many as 50% of American college students believe in the extramission theory.1

Although the fundamental features, anatomy, and physiology of the eye were documented by Galen (129–200 A.D.), an ancient Greek physician, in the second century A.D., it was Kepler, a close reader of Ibn Al-Haytham, who offered the first theory of the retinal image and the correct operation of the eye in 1604. He proclaimed, “Therefore vision occurs through a picture of the visible things on the white, concave surface of the retina.” Progress came slowly after Kepler, because little was known about the nervous system until the nineteenth century, and only recently have scientists acquired a more knowledge about how the brain apprehends the retinal image. But many questions still elude us.

History of the camera

In parallel with curiosity about human vision, human beings have also tried to mimic human vision by capturing images of objects with instruments. Around 1000 A.D., Ibn Al-Haytham, also known as the father of modern optics, invented the pinhole camera,2 and explained why the image was upside down. It was Johannes Kepler who further suggested the use of a lens to improve the pinhole camera in the 1600s. Capturing an image on a photographic plate was first achieved in the early 1800s. Consequently, photographic cameras began to be mass-marketed in the twentieth century. The photographic equipment with which we are all familiar today, such as the 35mm camera, flash bulb, Polaroid camera, and the point-and-shoot auto focus camera, all were developed in the twentieth century. The invention of the camera as we know it today paved the way for other technologies, including the moving image capture, and, later, the digital camera, in which electronic image-capture devices were used. In 1972, chemically processing an image onto photographic paper no longer became the sole destination of an image, because the first filmless electronic camera was patented by Texas Instruments Corporation. Filmless electronic cameras were made possible with the invention of solid-state image-capture devices called charge coupled devices (CCD) and metal-oxide-semiconductor (MOS) image sensors in the late 1960s. Since the invention of solid-state imagers, people have become more visually stimulated and oriented than ever before in history.

A comparison of camera chips and the human eye

The technological advancements of solid-state image-capture camera chip design and manufacturing during the past twenty-five years has made digital imaging more affordable and accessible to the general public. These advancements have become more visible to consumers in mobile products, particularly in cellular phones, in which there are still and video-camera functions. Although digital cameras are easily available today, the state-of-the-art image sensor chips used in these cameras exhibit a performance gap when compared with the capabilities of the human eye. How good these image sensor chips are today when compared to our eyes is a question that will be elaborated on.

It is possible to compare the capabilities of the human eye and state-of-the-art image sensor chips used in cellular phones or in mainstream PC and digital still cameras. It is also possible to compare the capabilities of the human visual system, including the eyes, the optic nerve, the visual cortex, etc. with a digital camera system which includes optics, image-capture and signal-processing chips and other camera apparatuses. The capabilities include ability to see different colors (spectral response), photo-element (pixel) characteristics (size, density, distribution), light sensitivity, light-intensity response range, functionality and operation modes, and signal processing capabilities.

Spectral response

A single light-sensing element in a solid-state image sensor is called a pixel. In the human eye it is called the photoreceptor. Both elements convert impinging light or photons into electrical signals. The human eye sees in the so-called visible spectrum, between 380nm (blue) and 750 nm (red), and utilizes two kinds of photoreceptors on the retina; rods and cones. The cones are used for color and daylight vision. Rods are responsible for night vision. There are three types of cone photoreceptors on the retina that contain different types of photosensitive pigments. The three types of cones are L, M, and S, and they have pigments that respond best to wavelengths of light that are long or red (peak at 564 nm), medium or green (peak at 534 nm), and short or blue (peak at 420 nm), respectively. The rods (R) are most sensitive at a wavelength of approximately 498 nm (green), as seen in Figure 1.3 Image sensor pixels in digital cameras mimic the photoreceptors in the human eye for color vision. They utilize three kinds of color filters (red, green, blue) on top of each pixel to convert light rays into electrical signals in different visible spectrums. Unlike the cones in the human eye, camera pixels and color filters can be designed to cover wide spectrums that are not visible to the human eye, for instance, the x-ray, ultraviolet, and infrared spectrums. In the category of spectral response range, camera pixels exhibit greater flexibility than those of the photoreceptors of the human eye. On the other hand, interestingly enough, the eyesight that humans possess has similar spectral characteristics as the sun. The solar light emission peaks in the visible spectrum as seen in Figure 2.4

Figure 1. Spectral absorption curves of the short (S), medium (M), and long (L) wavelength pigments in human cone and rod cells.3

Figure 2. The daylight solar spectral power distribution on earth.4

Pixel and array size

The size of pixels in today’s modern digital cameras is getting closer to the size of the photoreceptors in human eye. The typical human eye contains an average of 130 million photoreceptors. The diameter of the rods and cones varies between 1.0m and 8.0m, depending on their location on the retina.5 Today’s state-of-the-art image sensor chips contain 10 to 30 million pixels. Each pixel can be as small as 1.4m in diameter. To date there has been no image sensor that is 1.4m pixel in size or more than 8 million pixels. However, the human being has been equipped with photoreceptors that are as small as 1.0m and has more than 100 million photoreceptors; and this is since the beginning of existence. It is also estimated that the resolution of the human eye is equivalent to an imager sensor chip of 576 million pixels with a 120 degree field of view.6 Thus we still have a long way to go in improving the image-sensor pixel and array sizes used in cameras if we are to match the human eye.

Pixel distribution and formation

In the human eye the photoreceptor size and densities change, depending on their location on the retina. For example, no rods exist on the focus center of the eye, which is called the fovea. Color vision photoreceptors, which total only 10% of the eye’s photoreceptors, are located mostly on the fovea. There is an irregular distribution of photoreceptors which is unique for every human being, like a fingerprint. Yet, we all see things the same, such as colors (with the exception of people who are colorblind). In camera chips, however, pixels are arrayed regularly, in two-dimensions. As the image-processing techniques and algorithms used in camera systems are linear and do not closely mimic the signal processing that exists in the human visual system, regularly arrayed pixels are required.

Light sensitivity and response range

Although the pixel sizes in image-sensor chips are approaching the size of the photoreceptors in the human eye, camera systems are not yet close to being able to match performance in terms of light sensitivity and response range. The human visual system and photoreceptors can easily adapt to very dim and bright light, with a light-intensity response range of ten billion to one (1010:1).7 This response range goes from light conditions on a bright sunny day to dim night vision. Typically, a conventional consumer camera pixel has a light intensity response range of one thousand to one (103:1).8 In a camera system, details of a captured scene are either concealed in the dark regions or washed out by the bright light, depending on the exposure settings of the system. Thus, one could say that the human visual system works ten million times (107) more efficiently than that of consumer cameras in terms of transferring scenes into images.

Operation principle

In terms of operation principles, the photoreceptors in the human eye convert light rays into electrical signals with extremely rapid electro-chemical reactions which can detect a single photon. Typically, in the image sensor pixel of a digital camera the photoelectric effect is used to convert impinging photons into electrical charges. Electrical charges are collected and stored in each pixel during the exposure period. Collected electric charges in each pixel are amplified and converted into digital ones (logic-1) and zeros (logic-0) during image readout before the image is sent to higher processing elements, such as a personal computer, digital-still or video camera. It is possible for a single photon-counting camera to be developed. However, very special and larger pixel sizes and extra apparatuses are required to build such a camera system. Thus, we could say that it is almost impossible to build imaging pixels that have the capability and dimensions of the photoreceptors of the human eye with today’s state-of-the-art technology.

Signal processing capabilities

The captured image in the human eye is preprocessed before it is sent to the visual cortex of the brain. This preprocessing consists of a data reduction operation in which nothing is lost, with a compression ratio of 130 to 1, as only 1 million optic nerves leave each eye carrying the information from 130 million photoreceptors. This compression allows the brain to process information at a rate of 25 to 150 scenes or frames per second. Typically, every pixel in an image sensor chip is first transferred to higher processing units. A data compression method is either carried out with some loss of details in the image or the compression is never used. The transfer of frames in camera chips typically takes place sequentially, reducing the speed of the image-capture operation or frame rate. Different techniques are used to maintain a capture rate of, at most, 25 frames-per-second in camera chips. With today’s technology, image sensors that have a capture rate of one million frames per second have been proposed and can be manufactured for scientific applications.

The inherent inefficiencies of image-capture in today’s image-sensor chips are hidden by employing the limitations of the human eye. For example, solid-state image sensors have always been produced with row or column-vice uncanny stripes which are easily picked up by the human eye. However, psycho-visual experiments have shown that the human eye can only detect contrasts between two adjacent gray lines when the difference is greater than 0.5%. Thus, if a camera chip is designed to have a column to column or row to row contrast of less than 0.5%, these odd stripes would not be visible.

Conclusion

Humans are visually oriented and without a doubt, our eyes are considered to be our primary source of information. It is obvious that the human visual system is extremely complex and this complexity has fascinated human beings throughout history. Yet, the underlining principles and basic functions of human vision and the eye have only been discovered during the last two centuries. These discoveries have led research in how to mimic these functions, which has resulted in moving and still-photographic and camera equipment, and the image sensors chips used in digital cameras today. Even though human beings are only taking baby steps in fully mimicking the human eye, curiosity and scientific inquiry allows us to discover functions and features of the eye and the visual pathways that will increase our knowledge and help us to build better pixels and image sensor chips.

References

1. Winer, G. A., Cottrell, J. E., Gregg, V., Fournier, J. S., & Bica, L. A., “Fundamentally misunderstanding visual perception: Adults’ beliefs in visual emissions.” American Psychologist, 57, 417-424, 2002.

2. Ertan Salik, “Pinhole Cameras, Imaging, and The Eye” The Fountain Magazine, Issue 54, pp. 30-33, April – June 2006.

3. URL: http://en.wikipedia.org/wiki/Image:Cone-response.png

4. URL: http://www.handprint.com/HP/WCL/color3.html

5. Stefan Winkler, Digital Video Quality – Vision Models and Metrics, John-Wiley & Sons, Ltd., 2005.

6. URL: http://www.clarkvision.com/imagedetail/eye-resolution.html

7. R.C. Gonzalez and R.E. Woods, Digital Image Processing, Addison-Wesley, 1993.

8. M. Schanz, et al., “A high-dynamic-range CMOS image sensor for automotive applications”, IEEE Journal of Solid-State Circuits, vol. 35, no. 7, pp.932-938, July 2000.

There are many interpretations of the “image of God” among Christian theologians. However, almost all of them center on the supremacy of human beings over all of God’s creation. Not in the Qur’an, but in Islamic traditions, Muslims have a similar expression in the term of “the image of Rahman.” Rahman, one of God’s names, describes the quality of abounding Grace inherent in and inseparable from the Almighty. While some Muslim scholars have rejected this expression, because it evokes anthropomorphic thoughts about God, some have tried to interpret it in the light of general Islamic principles. Muslim scholars have brought forward many explanations about the term khalifa. After exploring these explanations, the Sufi understanding and Said Nursi’s approach will be presented. In a general sense, the figure of the khalifa will be discussed, as this is the most conspicuous figure in Islamic thought that represents the dignity of humanity. As such, this term serves to find a common ground for inter-religious dialogue.

The Image of God in Christianity

The term “image of God” is derived from Genesis 1: 26-27:

Then God said, “Let us make man in our image, after our likeness; and let them have dominion over the fish of the sea, and over the birds of the air, and over the cattle, and over all the earth, and over every creeping thing that creeps upon the earth.” So God created man in His own image, in the image of God He created him; male and female He created them.

These verses bring to light two ideas: God’s “image” and His “likeness.” At first glance, the two ideas awake one notion: resemblance to God. This resemblance can be understood both physically and ideally. As a result, anthropomorphic interpretations regarding these accounts abound (Migliore 140). However, many theologians disregarded the idea of physical resemblance when they carefully considered the other accounts. As a matter of fact, the related verse we are studying establishes a connection between such a “likeness” and “dominion” on the earth. This connection forces us to conclude that human likeness to God is the major factor for human dominion over the world. Therefore, the idea of the “dominion of humanity” in the world has become one of the interpretations of the verse.

Considering what distinguishes humanity from animals, theologians such as Augustine have interpreted “the image of God” to be human reason (McGrath 441). According to Augustine, God created humanity with the gift of the power of reason, which comes from the wisdom of God and makes people different from other creatures and the most powerful of creatures. Like Augustine, Thomas Aquinas thought that the image of God refers to the rational nature of human beings (Migliore 140). However, the Cappadocians interpreted the doctrine as being restricted to Adam’s heavenly life before falling down to the earth, arguing that being created in the image of God means being free from all weaknesses and disabilities, such as death (McGrath 442). So, according to this interpretation, after the fall of Adam and Eve, the image of God in human nature was defaced. Athanasius, on the other hand, relates the doctrine to the human capacity to relate to and partake in the life of God (McGrath 441). For William C. Placher, the image of God denotes the nature of human relationships (134). According to this explanation, to be human entails being involved in relationships not only with God but with other humans and the environment. The last interpretation of the image of God touches on human freedom. Many modern philosophers and theologians emphasize that humans are free, self-determining, and self-transcending (Migliore 141).

In conclusion, the four soundest explanations of the phrase “the image of God” found in Genesis 1:26, 27 are: dominion over the earth, the power to reason, relationships with God and other creatures, and human freedom.

Khalifa fi’l-Ard in Islam

No Qur’anic verse states that humans were created in the image of God; however, we can find similar expressions in the collections of hadith (sayings of the Prophet). Narrated by Abu Huraira, the Prophet said: “God created Adam in His own image.”¹

At first glance, this hadith seems to contradict some Islamic teachings since it implies anthropomorphism, which is strongly rejected by Islam, but Muslim scholars have interpreted this hadith in a way different to how it reads. Some have questioned the authenticity of the traditions implying anthropomorphism.² However, the majority have judged the authenticity of this hadith, interpreting it in accordance with the principles of Islam.³

There is another hadith: “God created man in the form of al-Rahman (the All-Merciful One).”4 Because this hadith is popular in Sufi circles, it has been interpreted mostly in mystical ways. Some ecstatic Sufis consider the human’s spiritual nature to be in the form of the All-Merciful. Said Nursi criticizes the Sufi interpretation of this hadith mentioned above. According to him, “the Pure and Holy God who administers the universe as easily as it were a house, has no equal or match, no partner or opposite” (Nursi 2005). The verse saying, There is nothing whatever like unto Him states clearly that “He has no form, like, or peer, there is nothing resembling or similar to Him.” Nursi explains the related hadith within the understanding of “divine names and attributes.” Accordingly, the entire universe is the place where God’s divine names and attributes (not His essence, as His essence is a mystery for us) are manifested. However, the human being is the brightest mirror, reflecting God’s divine names more even than the whole universe. In this sense, human beings have been created like a mirror to illuminate God’s beauty. Nursi says:

… A further indication may be derived from the following analogy: Animate creation and humanity are loci of evidences of the Necessarily Existent One, proofs and mirrors to the All-Merciful, All-Compassionate. These proofs are so certain, clear, and evident that just as we might say that a mirror reflecting the sun “has the form of (or is like) the sun” (emphasizing the brilliant evidence of the sun’s light), we also might say: “Humanity has the All-Merciful One’s form,” stressing the clear evidence within us, and the completeness of the connection in Him, of the All-Merciful. Therefore, the more moderate and balanced believers in the Unity of Being said: “There is no existent but He,” expressing clarity of the evidence and perfection of the connection. (Nursi 2005, p.11)

In the same way that the Biblical account mentioned above does, the following verse from the Qur’an clearly shows the importance of human beings before God:

Remember (when) your Lord said to the angels: “I am setting on the earth a vicegerent.” The angels asked: “Will you set therein one who will cause disorder and corruption on it and shed blood, while we glorify You with Your praise and declare that You alone are all-holy and to be worshipped as God and Lord.” He said: “Surely I know what you do not know. (God) taught Adam the names, all of them. Then, He presented them to the angels, and said, “Now tell Me the names of these, if you are truthful. … And (remember) when We said to the angels: “Prostrate before Adam!” (Baqara 2:30-34)

Muhammad Asad suggests that the term khalifa is used to denote the rightful supremacy of mankind on earth. More tellingly, the sequel of the verse strengthens the idea of the superiority of humanity. As seen clearly, the angels could not understand the creation of man and asked God why He had created this being. But God said He would create a khalifa, a kind of representative, because the angels, who had no ability to improve or regress, could not reflect God’s beautiful names or attributes properly. Adam’s ability to learn the names that the angels did not know points out his ability to develop mentally, physically, and spiritually. On the contrary, angels always remain at the same level. Because human beings have free will, which does not exist among the angels, they are capable of ascending to the heavens or going down to the abyss.

It would be helpful if we mention another verse from the Qur’an related to our discussion. The verse reads,

We did indeed offer the Trust to the heavens, and the earth, and the mountains; but they refused to undertake it being afraid thereof. But man assumed it; indeed, he is most unjust, most foolish. (Ahzab 33:72)

The scholars vary also in their explanations about what this “trust” means. While some think that the Trust is reasoning power, which distinguishes humans from all other creatures, others assume that it is religious responsibility, such as worship. However, Nursi has a different understanding. According to him, this “Trust” can be understood as the “ego”; the “I” part of the psyche, because humans can know the existence of God only with their ego, which is planted in their nature. How? Nursi answers this question as follows:

“An absolute and all-encompassing entity has no limits or terms, and therefore cannot be shaped or formed, and cannot be determined in such a way that its essential nature can be comprehended. For example, light undetermined by darkness cannot be known or perceived. However, light can be determined if a real or hypothetical bounding line of darkness is drawn. In the same way, the Divine Attributes and Names (e.g., Knowledge, Power, Wisdom, and Compassion) cannot be determined, for they are all-encompassing and have no limits or like. Thus what they essentially are cannot be known or perceived. A hypothetical boundary is needed for them to become known. In our case, this hypothetical boundary is our ego. Ego imagines within itself a fictitious lordship, power, and knowledge, and so posits a bounding line, hypothesizes a limit to the all-encompassing Attributes, and says: ‘This is mine, and the rest is His.’ Ego thus makes a division. By means of the miniature measure it contains, ego slowly comes to understand the true nature of the Divine Attributes and Names. Through this imagined lordship, ego can understand the Lordship of the Creator of the universe. By means of its own apparent ownership, it can understand the real Ownership of its Creator, saying: ‘As I am the owner of this house, the Creator is the Owner of this creation.’ Through its partial knowledge, ego comes to understand His Absolute Knowledge. Through its defective, acquired art, it can intuit the Exalted Fashioner’s primary, originative art.” (Nursi, 2005, p.552-3)

Whatever the interpretations may be, these two verses clearly articulate the superiority of mankind. Under the influences of these verses, Muslim thinkers, particularly Sufis, have placed humans at the center of creation. Needless to say, there are many other Qur’anic, traditional, and historical accounts that support human dignity and importance in Islam.

The verses we examine in the Bible and the Qur’an offer a common ground for dialogue among the three Abrahamic religions. But it must be said that this promising ground goes beyond religious identities because it is about the higher identity: being human. Therefore, not only religious persons, but also non-religious ones will appreciate what the Bible and the Qur’an emphasize on the subject of human dignity.

How do Biblical and Qur’anic accounts inspire us to interfaith dialogue?

It would be controversial to deduct anthropomorphic interpretations from such Scriptural information. To some extent, all religions have this kind of approach, where God is assumed in human form. This may be the result of two major reasons: first, people tend to understand and accept their Creator at their intellectual capacity. For example, because seeing, for people, becomes truth only with their “eyes,” they imagine a kind of “eyes” for God. Second, the Scriptures allow people to think of a human-like God because they address humans, who have a certain limited capacity. In other words, if the Scriptures had drawn a transcendental picture of God, their addressees, namely humans, would not have understood the idea. Therefore, the Holy Books contain many anthropomorphic details such as “the hand of God” or “the face of God.” Muslim scholars have come to the conclusion that all these details must be taken as metaphorical and understood/interpreted in the light of a basic principle revealed in the Qur’an:

There is nothing whatever like unto Him, and He is the One that hears and sees (all things) (Shura 42:11).⁵

McGrath points out that “the fact that humanity is created in the image of God is widely regarded as establishing the original uprightness and dignity of human nature.” (441). As it is readily apparent, being human is the first and the most important identity of human beings. The human dignity emphasized in the Bible and the Qur’an forces us to be respectful of each other, even though we do not share the same religion. As reported, the Prophet Muhammad, peace and blessings be upon him, once stood up when he saw a funeral. His companions told him that the deceased was Jewish. “Is he not a human?” replied the Prophet.⁶ So, human beings deserve to be seen with respect, as all are creatures of God.

Conclusion

I have tried to determine a common ground for interfaith dialogue. Which subjects are to be talked about and how the boundaries are to be drawn in such a dialogue is another issue, but I propose that the fact that humanity was created in the image of God, or as a khalifa of God on earth, should be the common ground. This idea, I believe, can be not only a common ground among the three Abrahamic religions, but also a starting point to launch dialogue and a factor supporting the dialogue during the process. I can summarize what I have said with the following: humanity is the apex of God’s creation and the terms “Image of God” and “khalifa fi’l-Ard” point to this superiority; all human beings must be respected because of the dignity granted to them by God, and no matter what their religion is, all humans are worthy of participating in dialogue. Religious people who have respect for their God must show respect to His creatures.

In brief, religious people are more likely to succeed in dialogue because they have a common ground to begin with. They consider humans as valuable creatures created in the image of God or as the khalifa of God. This consideration must give birth to respect among them. And this respect is the most significant factor nurturing a healthy dialogue.

Notes

1.  Bukhari V, 2299; Muslim IV, 2017.
2. Suyuti I, 167.
3. Nawawi, a prominent hadith scholar, points out that there are four opinions in this hadith. First, the Salaf, the scholars who lived before the emergence of Islamic theological schools, avoided stating anything about this kind of tradition and its implications. Second, some claim that the pronoun in the word “His image” (in Arabic: “suratihi” with the third person masculine singular suffix) refers to Adam not God. Namely, the meaning is the following: “God created Adam in his (Adam’s) (complete and perfect) image.” However, this interpretation, which seems wrong according to Arabic grammar, is rejected by many. Third, accepting the use of the pronoun for God, the majority of the scholars suggest interpretation according to basic principles. In this case, the phrase shows the dignity of human beings. Remarking on its importance, Muslims call the Ka’ba “the house of God.” Likewise, considering the image of God in human creation reminds us of the degree of excellence of human beings (See Nawawi XVI, 166). In this case, the last group suggests that we understand the hadith metaphorically.
4. Daraqutni I, 37; Shaybani I, 229.
5. Most Islamic scholars have interpreted the allegorical verses in the Qur’an in the light of verse 42:11, mentioned above. For example, they have explained “God’s hand” as His power and “God’s face” as His Essence.
6. Bukhari I/441; Muslim II/661

References

• Asad, Muhammad. The Message of the Qur’an. Kazi Publications Inc, 1980.
• The Harper Collins Study Bible (NRSV). London: 1993.
• Al-Bukhari, Muhammad b. Ismail. Al-Jami’ al-Sahih, Dar Ibn Katheer, Beirut: 1987.
• Coffman, James Burton. Coffman Commentaries on the Old and New Testament. <http://www.studylight.org/com/bcc/view.cgi?book=ge&chapter=001’.Abilene Christian University Press, Abilene, Texas, USA. 1983-1999.
• Al-Daraqutni, Ali b. Omar. Al-Sifat. Maktaba al-Dar, Madina: 1981.
• Gill, John. The New John Gill Exposition of the Entire Bible. <http://www.studylight.org/com/geb/view.cgi?book=ge&chapter=001&verse=026’.
• Ibn Katheer, Ismael bin Omar. Tafsir Ibn Katheer. Dar al-Fikr, Beirut: 1980.
• McGrath, Alister E. Christian Theology: An Introduction. Oxford: 2004.
• Migliore, Daniel L. Faith Seeking Understanding: An Introduction to Christian Theology. Michigan: 2004.
• Muslim, Ibn al-Hajjaj. Sahih Muslim. Dar Ihya al-Turath al-Arabi, Beirut.
• Al-Nawawi, Ebu Zakariyya Yahya b. Sharaf. Sharh al-Nawawi ala Sahih Muslim. Dar Ihya al-Turath al-Arabi, Beirut: 1972.
• Nursi, Said. Words. http://www.sozler.org/risnur/words/1.htm.
• Placher, William C. (Ed.). Essentials of Christian Theology. Kentucky: 2003.
• Al-Shaybani, Amr bin Ebu Asim. Al-Sunna li Ibn Ebu Asim. Al-Maktaba al-Islami, Beirut: 1979.
• Al-Suyuti, Abdurrahman bin Ebu Bakr. Tanwir al-Hawalik. Maktaba al-Tijariyya al-Kubra, Egypt: 1969.
• The Holy Qur’an. Trans: Yusuf Ali. Riyad: 1983.
• Al-Qurtubi, Muhammad bin Ahmad bin Ebu Bakr. Tafsir al-Qurtubi. Dar al-Sha’b, Cairo: 1952.
• Al-Tabari, Muhammad bin Jarir. Tafsir al-Tabari. Dar al-Fikr, Beirut: 1984.

When speaking of a huge emptiness in between the elementary particles, the French philosopher Jean Guitton (1901–1999) gives the following example:

Think of the proton of the oxygen nucleus as the size of a pinhead; then the rotating electron would draw a circle that traverses the Netherlands, Germany and Spain (assuming that the center of this orbit was France, as Guitton lived there). Therefore, if all the atoms that make up my body were close enough to touch one another, you wouldn’t be able to see me at all. [I] would be a particle of dust, just one thousandth of a millimeter.

If we could enlarge an apple to the size of the world, each atom, proportionally, would be the size of a football. We would then be able to learn everything about the atoms by taking one of those atoms and examining it in our hands, wouldn’t we?

No, we wouldn’t!

It isn’t this easy. Even if an apple were to be the size of the world, it would still be too small to attain enough information about its atoms. If we want to see the nucleus of the atom, we must enlarge it to the size of a town, not a football. Then the nucleus, which is the size of a football, is in the middle, and one of the electrons, orbiting 1 kilometer away, would be no larger than a walnut.

Now let’s apply this example to the hydrogen atom, which is the smallest atom. If the nucleus of a hydrogen atom were enlarged to the size of a football then the atom itself would be a sphere with a diameter of 2 kilometers.

Quantum field

The discovery of the atom is in fact the discovery of empty space. It might sound strange to hear the words “huge” and “emptiness” in the same sentence when talking about the atom.

One night, a pessimist, an optimist, and a physicist were looking at the cloudless sky. The pessimist said, “What a great emptiness,” while the optimist said, “There are countless stars.” The physicist, on the other hand, couldn’t say anything, because he wasn’t sure whether what they had seen was a vast amount of objects or a vast field of emptiness.

The developments in modern physics in recent years have changed concepts such as, “substance,” “particle,” and “vacuum.” Vacuum is usually defined as “the living environment, life breath, or energy” of the universe.

The vast vacuum that physicist sees in the sky is what we call the quantum field

The quantum field is formless and shapeless. It is the field of all forms and the basic essence of the universe. The durable and solid substance that we call a particle is the condensation of this field into small units. The quantum field is the environment of activity, transportation, and communication, all at the same time. It is noteworthy that this approach is very close to the ancient approach that claims that space is full of ether.

Albert Einstein defined matter as the space region in which this field was extremely condensed. According to the understanding of the new physics, both the matter and the field of the matter are the same thing.

According to quantum physics, all matters in space are like islets in an ocean, and are connected to each other through subjacent earths. In the concept of a quantum field, space is a stable integrated whole and unity of waves and these interactions happen in “waves.”

Vacuum is not emptiness

The vacuum was once believed to be a place with nothing inside it. However, the universe has a beginning, and everywhere in this universe was once a single place that later came into existence. Therefore, it is impossible for a place in which “there is nothing” to exist in the universe. In brief, subsequently, there must have been something everywhere that has been created. Just as there is no dry place in the sea, there cannot be any emptiness in this sea of existence that was created out of nothing. Underlining this truth, quantum physics defines the universe as a whole and says there is no emptiness in the absolute sense. In other words, the universe in which there is no “empty” space is a world that has been “called into being.”

If everything around us, even human beings, consists of atoms, most of which are made up of emptiness, and if in fact the actual physical structures that compose our bodies are so few, then why can’t we go through walls or closed doors, like cartoon characters? What makes matter so solid and durable?

In fact it is not easy to answer this question. Electrons are created in small places, like atoms, and have been given phenomenal speed. An electron moves at 1,000 kilometers per second (that means it rotates one million times around the nucleus). As a result of this phenomenal speed, the atom becomes a tough and solid mass. We can compare this to airplane propellers that appear to be a solid and flat surface when spinning.

The amazing electron

The features of electrons, such as being able to pass through two holes in an obstacle at the same time (no other particle can do this) have astonished scientists and brought out a metaphysical dimension that are beyond the wave nature of light. The granular structures of subatomic particles contradict the understanding of matter. According to the findings of quantum mechanics, the particle is in fact nothing but a dynamic effect and movement. The particles can be composed of energy or they can be entirely converted to energy. The classical concept of elementary particle is becoming obsolete in today’s world.

Nevertheless, the changes in our perception of matter do not necessarily mean matter is unreal. The truth is that particles of matter do not have a constant reality or an independent essence, in contrast to what has been assumed. Whatever seems to be or is reflected as matter, energy, or value, or whatever we call it, is nothing but the manifestation of the Divine Names of the Creator Who created “nothingness.”

Think of a shadow play. The image that the audiences see on the curtain, which is far from the source of light, is not “real.” The real thing is another object that is in front of the source of light or behind the curtain. What we see is the reflection of the object itself or its movements. If we don’t know how this play has been staged, we may think that the image on the curtain is real. Even though there is an image on the curtain, it does not have its own existence and is not real. In the same way matter exists but its existence and its being in this condition is not something under its control.

Before the realm of the quantum was discovered, Newtonian physics had accepted matter as being solid, durable, and constant. Everything we touch, such as walls, trees, and all the objects we see have the solid and durable condition of matter. But if one looks at an object through an electron microscope, they will see that 99% is vacuum and 1% is light. We can form circle of light if we swing a light source in a dark room. If we add a second, third, and fourth source, and move them so that they can form illuminated spheres, someone who is observing from a distance will perceive a three-dimensional sphere instead of a two-dimensional illuminated circle. Thus, we can understand that by increasing the number of spheres we form a three-dimensional model of matter. According to quantum physics, matter found in the universe is pretty much like this example. In short, matter does not consist of a combination of solid particles. There is almost no difference between the “building stone” of human beings and the image of human on television. And we can say that just as the television broadcast disappears when there is a power cut, it is also possible for this universe, which seems so permanent, to disappear with one command.

A television broadcast is constantly being renewed through the transmission of pictures and sound by means of electronic signals. As in the example above, if our existence is like the image on television, then can we say that the universe is also being renewed every second like a TV broadcast?

None of the objects we see (trees, birds, humans, etc.) take their existence from the concrete reality of the matter that we perceive. Thus, they must receive their existence from the power and the names of the Creator Who creates everything out of nothing and keeps it in perpetual motion. In brief, although created out of nothing, existence is being created all the time.

In order to get a sharp image, ideally one point on the image (film) should receive light rays from only one point on the object. In practice, this ideal case can not be achieved in case of a large pinhole. If we have a large pinhole, as seen in Fig. 4, the light rays emerging from one point on the object reaches multiple points on the film. Also, multiple points on the object can arrive at a single point on the film. The result of both cases is a blurry image. For a small pinhole, however, there are light rays emerging from a point on the object in all directions, and only a very small amount of light is received on the film. To produce a decent image on the film, the exposure time needs to be very long, especially when a very small pinhole is used. Of course, we can make the pinhole a little larger to capture more light. But, wait! This would make the image blurry. Therefore, for pinhole photography, the size of the pinhole sets the quality of the image and the minimum exposure time. Also, we can take the picture of a still object, but a moving object cannot be captured easily by a pinhole camera due to the long exposure time. One important question is: Can we make reduce the size of the pinhole size to increase the quality of the image? Well, physics says: “No!” Fig. 5 shows a comparison of the images of a filament taken by a pinhole camera.⁶ As the size of the pinhole gets smaller and smaller, the effects of the diffraction phenomenon are more and more pronounced, and the image becomes blurry again. We also notice that the image is barely formed with a very small pinhole, indicating that very little light is received.

How can we gather more light and still make the image sharp? Can we achieve this with just the pinhole? Apparently not. That is why we mention lenses when talking about any imaging system. This is what a lens basically does. A lens gathers more light, and still preserves the one-to-one correspondence between the points on the object and those on the image. So, a lens is very useful for imaging. Most cameras have one or multiple lenses. Our eyes have lenses. We should remember, though, a pinhole camera takes a picture, but the compromise is the exposure time. Now, we see that a lens solves the exposure time problem, but is there a price to pay? To answer this question, let’s take a look at once again Fig. 2, where we see two pictures, one taken by a pinhole camera, and the other one by a lens camera. Look at the pictures carefully, and try to understand the difference before proceeding. As you probably observed, in the pinhole camera image everything in the picture is in sharp focus, from the close-by plants to the far distant beacon, and the clouds in the sky. However, in the lens camera image, only the closest daisy is in focus, and the other daisies, only a few meters away, are blurry. Indeed, we lose the depth of field in our images when using a lens camera. Depth of field can be defined as “The distance between the nearest and farthest points that appear in acceptably sharp focus in an image.” This is actually something we live with everyday. Try to focus your eyes on a mountain far away; the objects that are very close will not be in focus anymore. So, our eyes, consisting of lenses, also have limited depth of field. A nautilus eye, on the other hand, has an infinite depth of field, as it has a pinhole eye. Therefore, the price paid for gathering more light with a lens is that not everything will be in focus.

We can understand why lens cameras have a limited depth of field while a pinhole camera has nearly infinite depth of field if we consider the focusing mechanism of a lens. Given a pre-determined film position, a lens can only form sharp images of an object at a certain distance from the lens. Other points that are farther from or closer than same section of the object will be out of focus. However, if the size of the object is not large, we usually do not notice this effect. When we want to take pictures of close-by objects, then this effect is clearly seen, as Fig. 2 (b) shows.

Actually, we can correct this problem. The image of the farther points of the object forms at a farther point on the film. So, multiple light rays coming from one point will end up on the film. If we place an aperture next to the lens, then we can block some of these light rays. If we make the size of the aperture sufficiently small, we can get a sharp image of the farther point. Our original question about the lenses can be posed once again at this point: By using the aperture we make the image sharper, but what do we lose? Of course, since we block some of the light rays, we lose the light-gathering ability of the lens. Now, if we make the aperture size smaller and smaller, we finally reach the pinhole, and an almost infinite depth of field!

Our eyes also use similar mechanism of placing an aperture. The amount of light allowed to enter each eye is controlled by the iris, a circular diaphragm that opens wide at low light levels and closes to protect the pupil (the aperture) and retina (light detector of the eye) at very high levels of illumination. As illumination changes, the diameter of the pupil (positioned in front of the crystalline lens) reflexively varies between a size of about 2 to 8 millimeters. When illumination is very bright, the pupil narrows and light rays from the side are excluded from the optical pathway.⁷ The result is a sharper image on the retina. A very narrow pupil (approximately 2 millimeters) produces diffraction artifacts that spread the image of a point source on the retina, similar to the image of the filament captured by a very tiny pinhole (Fig. 5)

In conclusion, a pinhole camera is a very instructive tool for learning about imaging concepts. A pinhole camera has an infinite depth of field and the ability to produce sharp images regardless of the distance of the objects. This comes with a price, though: the small size of the pinhole limits the amount of light received by the film, so long exposure times are needed. A lens helps to gather more light, but compromises the depth of field. These concepts are used in imaging technologies, and can be found in the eyes of living organisms.

Notes

1. E. Hecht, Optics, 2nd edition, pp. 199. Addison-Wesley Publishing Co.
2. http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T045986A.gif.
3. http://www.kosara.net/gallery/.
4. http://www.eyedesignbook.com/.
5. http://www.spylife.com/pinholecam.html.
6. http://www.umiacs.umd.edu/~ramani/cmsc426/Lecture3.pdf
7. http://www.olympusmicro.com/primer/lightandcolor/humanvisionintro.html.

Radar, a contraction of the words radio detection and ranging, is an electronic device for detecting and locating objects. It operates by transmitting a particular waveform pattern and detects the nature of the echo (return) signal.1 Radar is used to extend the capability of the man’s senses, especially that of vision. We can think of radar as being a substitute for the eye, although it can do so much more: it can see objects through such impervious conditions as darkness, haze, fog, rain, and snow, for its wavelengths are much longer than those of visible or infrared light. The human eye works as a passive device, since the object is illuminated by sunlight or other light sources. However, radar produces its own illumination via electromagnetic waves, which means that it is an active device. 

APPLICATIONS OF RADAR AND RADAR IMAGING

Radar is used in civilian applications as air-traffic-control radar to guide aircraft to a safe landing, and in commercial aircraft as radar altimeters to determine height and weather avoidance, as well as wind-shear radars to navigate in severe weather conditions.

The military uses radar for surveillance and weapons control. Examples of such radars are DEW (Distant Early Warning) and AEW (Airborne Early Warning), which detect aircraft, long-range search radars, and guided missile radars.2

Research scientists use radar as a measurement tool. Radars have been placed on satellites, space modules, and shuttles to explore meteors, planets, and other objects in the solar system.

In the case of an imaging radar, the radar travels along an airplane’s or a space shuttle’s flight path. The area underneath is illuminated by the radar, and the radar architecture builds the image as it moves on the top of its footprint (Fig.1). The radar image’s finer resolution is achieved by using a very long antenna array to focus transmitted and received energy into a sharp beam.2 The beam’s sharpness defines the resolution. Similarly, such optical systems as telescopes require large apertures (mirrors or lenses that are analogous to the radar antenna) to obtain fine imaging resolution. Synthetic Aperture Radar (SAR) is a common and very popular technique in radar imaging that achieves a very fine resolution.3 In the following sections, we introduce and explain different types of SAR imaging techniques.

SYNTHETIC APERTURE RADAR (SAR)

SAR refers to a technique that synthesizes a very long antenna by combining echoes received by the radar when it travels.4.5 Typically, SAR is used to produce a two-dimensional (2-D) image. One dimension in the image is called range (or along track), and is a measure of the “line-of-sight” distance from the radar to the target (Fig.l). Range is determined by precisely measuring the time from a pulse’s transmission to receiving the echo from target. The range resolution is determined by the transmitted pulse’s width (i.e., narrow pulses yield fine range resolution).

The other dimension is called azimuth (or cross track), and is perpendicular to range. Usually, the length of the radar antenna determines azimuth resolution. However, a good azimuth resolution requires a radar antenna that is not practically carried by an airborne platform, for imaging radars are much lower in frequency (1 to 10 GHz) than optical systems (4,000 to 8,000 GHz). The length of the required antenna could be around several hundred meters, which obviously cannot be carried by an air vehicle.

However, SAR differs from other radars in that it collects data along the flight path when it travels, instead of using a large antenna. Therefore, a very small antenna is adequate for the job. After collecting the data, it processes this aperture data as if it came from a physically long antenna. The distance the aircraft flies in synthesizing the antenna is known as the synthetic aperture. A narrow synthetic beamwidth results from the relatively long synthetic aperture, which yields finer resolution than what is possible from a smaller physical antenna.

SARs are not as simple as described above. Transmitting short pulses to provide range resolution is generally not practical. Typically, longer pulses with wide-bandwidth modulation are transmitted, which complicates range processing but decreases peak power requirements on the transmitter. For even moderate azimuth resolutions, a target’s range to each location on the synthetic aperture changes along the synthetic aperture. The energy reflected from the target must be “mathematically focused” to compensate for the range dependence across the aperture prior to image formation. Additionally, for fine-resolution systems, range and azimuth processing is coupled (dependent on each other), which greatly increases computational processing. The trick in SAR processing is to correctly match the variation in frequency due to motion (moving target or moving radar) for each point in the image.

An example of SAR imaging is shown in Fig. 2. The colors in the image reflect the received signal intensity. The strongest signal level is red, whereas the weakest is black. The figure is a SAR image of San Francisco, California, obtained by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on October 3, 1994. The size of the image is about 26 miles by 36 miles. The center of the area is 37.83 degrees north latitude, 122.38 degrees east longitude.

This particular SAR image is a good illustration of how SAR distinguishes urban areas from nearby relatively less populated areas. Such densely populated regions as downtown San Francisco (center) and the city of Oakland (at the right across the San Francisco Bay) show up as red images due to the alignment of streets and buildings vis A vis the incoming radar beam. The bridges in the area are easily detected by the imaging radar, including the Golden Gate Bridge (left center) at the opening of San Francisco Bay, the Bay Bridge (right center), and the San Mateo Bridge (bottom center). All dark regions on the image represent smooth water. Radar also easily detects the major faults in the area: those bounding the San Francisco-Oakland urban areas and the San Andreas Fault (at the lower left), As seen from the image, faults are shown as dark straight lines in the SAR image.

INCERSE SAR (ISAR)

While SAR images a region of the Earth from an airplane or an air shuttle, Inverse SAR (ISAR) images a flying object, such as airplane or an asteroid, from land-based radar. ISAR is very popular, and also very critical in military applications.6 It is commonly used for identification purposes. In a possible war scenario where there are too many aircraft in the sky, it is almost impossible to guess which one is friendly or hostile. In that case, ISAR imaging technique is used to identify the approaching aircraft and classify it from a collection of possible targets.

In theory, ISAR is an imaging technique that maps the locations of dominant scattering points of a target based on the multi-frequency, multi-aspect, backscattered data.7 In this data, the signal’s amplitude reflects the magnitude information of the scattering points on the target, while the backscattered signal’s phase is related to the location information of the scattering point off the target. After collecting this 2-D raw data, several signal-processing tools extract from this data the amplitude and location information of the scattering centers. Then, a 2-D image of the target is constructed by using a convenient image processing technique.

An example of ISAR imagery is shown in Fig. 3. The model of the test airplane (C-29 model) is shown at the lower portion, while a 2-D ISAR image of the airplane is constructed at the upper portion of Fig.3. The measurement is taken at the center frequency of 10 GHz, where the frequency bandwidth is 16 GHz. The data is collected from 0.10 steps to cover the entire 3600 azimuth. At the end, a 2048 by 2048 2-D grid is constructed by using the ISAR algorithm. By comparing both, it is seen that ISAR imaging provides accurate target information. By looking at this image, it is very easy to identify and classify the aircraft.

ISAR is an active operation of the radar at the target’s far field. Both receiving and transmitting antennas must be far away from the target. Recently, new ISAR imaging techniques that allow passive radar operation have been discovered. Antenna SAR (ASAR) and Antenna Coupling (ACSAR) imaging techniques use direct radiation from an antenna mounted on the near field of an airplane or a ship to image the dominant radiation points off these platforms. In these cases, the radar functions only as a receiver, for the target’s own antenna provides illumination to the target. These techniques are mainly used to determine the dominant radiation points off the target to explore ways to cancel or mitigate undesired extra radiation from the target’s platform.

The development of fast computers during the 1980s allowed researchers to apply intensive computational electromagnetic (CEM) tools that ultimately led them to develop new SAR/ISAR algorithms. One of the most appreciated and widely used tool is Interferometric Synthetic Aperture Radar (INSAR) imaging, which allows the extraction of height information that can be used to render 3-D topographic views of a SAR scene.

INTERFEROMETRIC SAR (INSAR)

Radar interferometry involves coherently combining radar measurements made by two or more radar antennas displaced by a relatively small distance.8 Depending on the relative geometry of the two antennas, the combined measurements can be turned into measurements of surface topography, topographic change, or displacement over time. Mapping precision of around 2m in three dimensions over a wide area is now possible from airborne interferometric radars.

Here is how an INSAR works: A radar system launches electromagnetic energy to scan the ground terrain to be imaged. Two radar antennas collect the backscattered wave to obtain two different snapshots of SAR image. To avoid phase ambiguity, these antennas must be close enough to each other. Since the waves travel different distances from a particular scatterer to each antenna, the resultant phases of each SAR image is different. In the next step, an image called interferogram is formed by multiplying one SAR image by the complex conjugate of the other SAR image. The phase of the interferogram represents the differences in range to the scattering centers of each pixel in the image. These differences are caused by the terrain’s topography. Then, a signal-processing algorithm converts this phase information to extract the terrain’s topographic features. Finally, a 3-D INSAR image of the region is formed by combining the SAR images with the height information.

An example of INSAR imaging is illustrated in Fig.4, which depicts the Long Valley of east central California. The images were taken by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour during its two flights in April and October 1994. The four images show the steps necessary to produce 3-D data from radar interferometry. The image covers an area of 21 by 37 miles. The radar illumination is from the top of the image. The bright areas are hilly regions of big rocks and pine forest; the darker areas are the relatively smooth, sparsely vegetated valley floors. The curving ridge running across the image’s center from top to bottom is the northeast rim of the Long Valley caldera, a remnant crater from a massive volcanic eruption roughly 750,000 years ago.

The image in the upper right is an interferogram of the same region, constructed by combining data from the April and October flights. The different phases are shown as different color levels. These variations are caused by elevation differences in the area. The same color levels indicate that those regions have same altitudes. The image in the lower left shows a topographic map derived from the interferometric data. The black bold contour lines represent levels of elevation. In this particular image, elevation levels are spaced at 250-meter intervals. The last image is a 3-D view of the northeast rim of the caldera, looking toward the northwest. As can be seen from the image, it is possible to extract such geologic structural and landform features as elevation, vegetation, and soil type with the help of INSAR processing.

Another example of INSAR imaging is shown in Fig. 5, which depicts the Washington, DC, Mall area. A similar approach is used to form this 3-D image. The region starts from the Capitol building (top) to the Lincoln Memorial and the Arlington Memorial Bridge (toward the right bottom). The Washington Monument is very easy to observe at the center of the image. The bright areas (from white to yellow) represent higher elevation places; darker colors (from green to dark blue) represent the areas of lower elevation. The Potomac river (right bottom of the image) and the reflecting pool (from the Lincoln Memorial toward the Washington Monument) are all in dark blue because of the water and the lowest elevations. We can also clearly distinguish Constitution Avenue running from bottom to top. The green regions are intermediate elevation consisting mostly of vegetation. As seen from the image, the highest elevation is the top of the Washington Monument, the Library of Congress building, and the Capitol building.

CONCLUSION

In this paper, we presented a survey study of radar basics and radar imagery. It is obvious that radar has been a very important and useful tool throughout the 20th century, both in the military and industry. With developments in the computer era and new imaging algorithms, it looks like it will be a very critical tool in the 21st century as well. It is now possible to simulate very complex models and targets in a reasonable computation time in radar frequencies thanks to new developments in computational electromagnetics methods (CEM). Examples of those are Xpatch9 (a high frequency code that can predict the scattering from large, complex bodies) and FISC10 (a fast simulator of electromagnetic bodies at high frequencies). While computers continue to grow faster and faster, new electromagnetic simulators are also getting faster and more efficient. As a result, more compact, fancier, faster, and more accurate radar-imaging techniques are being developed.

REFERENCES

1. Morris, G. V. and Harkness, L. (1996) ‘Airborne Pulsed Doppler Radar’, Artech House.
2. Mensa, D. L. (1981) ‘High Resolution Radar Imaging’, pp. 185-189, Artech House.
3. Wehner, D. R. (1994) ‘High-Resolution Radar’. Artech House.
4. Carrara, W. C., Goodman, R. S. and Majewski, R. M. (1995) ‘Spotlight Synthetic Aperture Radar: Signal Processing Algorithms’, Artech House.
5. Franceschetti, G. and Lanari,. (1999) ‘Synthetic Aperture Radar Processing’, C. R. C. Press LLC.
6. Baltes, H. P. (1980) ‘Inverse Scatteiing Problems in Optics’, Springer-Verlag.
7. Chu, T. H. and Lin, D. B. (1991) ‘Microwave diversity imaging of perfectly conducting objects in the near-field region’, IEEE Trans. Antennas Propagat., vol. 39, pp. 480-487.
8. Askne, J., et al. (1997) ‘C-band repeat-pass inter ferometric SAR observations of forest, IEEE Trans. on Geoscience and Remote Sensing, vol.35, pp. 25-35.
9. Lee, S. W. (1992) ‘Test cases for XPATCH’, Electromagn. Lab. Tech. Rept., ARTI-92-4, Univ. of Illinois.
10. Ctr. Computat. Electromagn. (1997) ‘User’s Manual for FISC (Fast Illinois Solver Code)’, Univ. Illinois, Urbana-Champaign, and DEMACO. Inc.

We are often told that the West believes in freedom of expression for all. If this belief were practised sincerely, would we not see many different images of the many peoples and cultures in the world, images as diverse, rich and plural as the reality is? But we do not. We see overwhelmingly one view of the world, one way of living in it and understanding it. In theory, an individual is free to make and put on air whatever images he or she likes, but in practice whatever does not conform to that dominant one view does not get much exposure and so remains without effective influence. If you own all the motorways in a country; you do not need to close down the little byways and side-roads; you can be sure that all the big traffic will move on the big roads. Indeed, leaving the side-roads enhances the comfortable (but false) impression that one is free to move as one likes, to pick one’s own route through life. In the same way, when a whole system of media networks are constantly putting out a particular image or idea, it really doesn’t matter how many little ‘slots’ are left open for those who wish to express a contrary image or idea. That different image is never on the air long enough to persuade significant numbers of people who are inundated with the dominant image the rest of the time. Besides, how many individuals can afford to set up a radio or TV network; and even if they can, how do they get or keep a license to broadcast if their perspective is subversive of the dominant culture?

The task of the enormous media output generated by the West, in particular by the United States, is global management of public tastes and options. It does not work by forcing individuals to think or say or buy particular things; it works by limiting the possibilities of what might be said or bought. You do not need to chain people up in order to control their movements; a more efficient way (certainly where large numbers are involved) is to control the whole of the space in which they can move. Control is exercised by regulating the scope – the horizons – of what is possible. This form of control is the most insidious and dangerous ever devised: any individual, at any individual moment, has the illusion that he or she can think, say, wear, do, whatever he or she, at that moment, pleases. But when the sum of moments is added up, it shows, for the overwhelming mass of people, a staggering uniformity of perceptions, tastes, choices, actions. That is why, for example, in India where the vast majority of people (Hindus) support a prohibition on the eating of animal flesh, Macdonald’s hamburgers ear be a great commercial success, or why the poorest people in the ‘Third World’ come to believe that they have at last got their share in the good things of this world when they spend their scarce earnings on a bottle of Coca-Cola. The cultural diversity of the world is being systematically reduced:for the great mass of people, it becomes harder and harder to imagine even that there should be, let alone could he, alternatives. At the same time, because the alternatives are, so to speak, off the air, people become culturally orphaned, lose contact with their past and struggle to hold on to any identity except as isolated individual consumers in the international market-place.

You may say images are only images; nobody believes that they are real. After all, people do not believe that the commercials they see represent reality. Of course they do not. But that does not prevent them being powerful. The greatest teachers of mankind in every culture have taught through the imagination: they used poems, parables, similitudes, stories. The reason is that in such forms, the whole resources of language are employed, not just, for example, the rationality or logical power of words. A well-told story that depicts sacrifice is more deeply affecting, more deeply persuasive, than any number of beautifully argued philosophical treatises explaining the merits of sacrifice. That is why a constant barrage of films, TV series, commercials, showing the success of ‘the American way’, alongside the failure or irrelevance of any other way is so potent a Weapon in cultural (and therefore political and commercial) dominance. The effectiveness of images cannot he overestimated: if there is a danger, it lies in underestimating their power.

Why is it managed in this way?

It is tempting to explain why the West promotes itself at the expense of other cultures as a political or economic conspiracy. But the reasons may he deeper than that. Historically, in stark contrast to Islamic civilization, Western civilization has never been assimilative: it has not wanted to acknowledge the virtues of other peoples and cultures except when it could insist that those virtues belonged to the past (and now belong in an anthropological museum), or could confine them to very specific skills – such as the making of silk or the use of acupuncture among the Chinese, or calligraphy or geometric ornamentation in the Arabic-Muslim world. By contrast Western popular consciousness is incapable of assimilating, for example, the historical fact that serfdom was first abolished in Europe not by the rulers of the European Enlightenment, but hundreds of years before them by the Muslim Turks – which is only one of the reasons why Turkish rule in Europe was so popular (even with non- Muslims) and endured so long.

Western expansion has always been based on the conviction that, in what counts, the West had everything that was good to offer, and it was the historical destiny of everybody else to accept it. That is why to this day, even the most transparently selfish, aggressive policies are represented as altruistic: the West still claims to be sending aid to Africa, Asia, Latin America, when in reality those parts of the world are being drained of their wealth to sustain the West’s affluence – the flow of wealth (in cash as well as materials) is not from but to the West In the past, when Europeans conquered lands and peoples, the vast majority of them genuinely believed they had given to the conquered peoples the necessary first lesson in liberty. The degree of self-delusion on such questions is so deep-seated that almost no amount of history (and there is a great deal) can shift it. What is the source of this self delusion?

It seems likely that the twin roots of this attitude are certain Christian doctrines and Greek-Roman legal practice. From the Jews’ concept of themselves as the only favorites of God, the Christians inherited the idea of being special, chosen to be ‘saved’ through the mystery of believing in Christ. It is hard to understand now, but it really was a part of formal Christian belief to say that non- Christians could never be virtuous – an irrational idea which eventually led to the invention of ‘limbo’, a place neither heaven nor hell, to which non-Christians who had been virtuous or great (Socrates and Plato, for example) could go. Because believing was already equivalent to being ‘saved’, Christians, when they obtained political power, felt justified in suppressing or even eradicating non-believers and heretics. The sincere horror in the modern West of anything resembling ‘religious’ government derives from memories of their long history of incapacity to be both religious and powerful and tolerant at the same time. 

After secularism was established as the ‘civilized’ form of governance, the idea of being special and ‘saved’ came to be transferred to the ‘nation’. This was truer of Protestants who (unlike Catholics) had separate national churches which broke off allegiance to the Pope in Rome. The ‘nation’ was made up of ‘citizens’ or ‘subjects’ who – following the pattern of the ancient Greeks and Romans – enjoyed full legal status as ‘persons’. Non-nationals did not enjoy such status. The Greeks’ term for non-Greeks was ‘barbarians’ (a cultural rather than racial distinction). This term, varied as ‘heathen’, ‘savage’, ‘primitive’, etc., was indiscriminately applied to any peoples the European nation-stares conquered. The conquered peoples were denied the very privileges and dignities which the Europeans daimed as a justification for taking complete control of their lands and resources. If and when the Europeans judged that the ‘barbarians’ were sufficiently ‘civilized’, then (in theory) some sort of status approaching that of Europeans might be extended to them. How reluctantly such rights were granted, if ever, is too well- known to need rehearsal.

Of course, in very recent times, official attitudes (and constitutions) have changed: in the Western countries themselves, all people are supposed to enjoy the same status. The difficulty has been that die legal constitutions do not fit well with the mental and emotional constitutions of the vast majority of Western people: popular culture necessarily reflects the still popular feelings of cultural and racial superiority – that to be Western is to be good and to be non-Western is, at the very least, to be most unfortunate. There was nothing unusual or odd about Western commentators during the Gulf War speaking of ‘bringing Saddam Hussein to heel’ – an expression normally used of disobedient dogs which must be brought under control. Despite the far more appalling crimes of a Karadzic or Milosevic in Bosnia, it is quite inconceivable that any Western commentator would dare to say that ‘Karadzie must be brought to heel’. Similarly the genuine sense of shock and dismay at the events in Bosnia is directly related to those events happening in Europe. The implication is that the same events elsewhere are not dismaying – thus, the ‘ethnic cleansing’ of Muslims from Burma (about half a million have been expelled) has passed without comment, so too have the horrors against Muslims in Armenia, or the frequent massacres of Muslims in India which (in deference to the sensitivities of the Indian government) are invariably described in the Western media as ‘communal disturbances’.

The ethos, the make-up, of Western self-image needs this dichotomy of ‘saved’ and ‘un-saved’, ‘us’ and ‘them’, needs an ‘alien’ to hate and fear. Now that the ‘evil empire’ of Communism has collapsed, it is Muslims who will increasingly be called upon in the popular imagination of the West to play the part of ‘them’.

What can be done to resist?

First of all, it is necessary to understand that making propaganda images is a slow subtle activity. Its effectiveness is general and collective, not particular and individual; it operates in the background rather than the foreground; it has a long wavelength, not a short one. It is not a question of a sudden burst of abuse against an enemy, like one angry individual throwing a heavy lump of dirt. No; it is more like the force of gravity – the most powerful in the universe – it operates unseen (mostly unquestioned) over huge distances upon the whole mass of a culture. The ground has to be prepared, the image built up steadily with every individual opportunity exploited as it arises. The negative image of Islam has been available to Europeans since the Middle Ages; it can he argued that Christian Europe defined its own identity as against the Dar al-Islam whose prosperity and power it had envied for so many centuries. It is therefore easy to build on this background consciousness whenever the foreground presents an opportunity – a terrorist attack, a rise in the price of oil, a rich Arab mistreating his wives or servants, and so on. All such occasions provide the material out (if which popular fictions are woven – films are only one example of such fictions.

Secondly; it is necessary to seek nut and hold to the truth in spite of the power and pervasiveness of the negative images. It is necessary to demonstrate and affirm the humanity and inclusiveness of Islamic civilization. Wherever die Muslims governed, they enhanced (and not diminished) the quality of life and culture of the ‘native’ people. They became a part of the people they ruled so that, in a very short rime, it was hard to tell them apart in terms of role or relevance in the culture of the region as a whole: East and West have only ever been united as one civilization under Islam.

Finally, it is necessary to answer false images with true ones. As well as complaining that the recent film of Columbus starts with the ‘ethnic cleansing’ of Spain (minarets pulled down, etc.), Muslims need to demonstrate that Columbus was not setting off into the unknown hut following paths long since travelled by Muslims – nor Arabs, in fact, but black men from Mali who sailed to South America – some six hundred years before Columbus did – and drew maps of it, intermarried with the ‘native’ people, then sailed tip the Mississippi to meet and intermarry with the Iroquois – for all of which there has been reliable documentary and archaeological evidence (including a map of the ‘New World’) made available by Western scholars for seventy years. Rut that evidence is something that does not fit at all with the cinema image of blacks as indolent savages and Europeans as eager explorers bursting with white-man’s courage and curiosity. Muslims should not hope that the Western imagination, while it retains its character as Western, will correct its own false images – it may correct its facts but (for reasons already explained above) no amount of documentary facts can ever compete with a good story. It is tip to Muslim’s themselves to provide both facts and the telling of those facts in a form that can put the false images right.