The article by Joachim Wambsganss Essay Example for Free

The article by Joachim Wambsganss Essay The article by Joachim Wambsganss discusses the nature and functions of gravitational lenses that both help and challenge our understanding of the celestial bodies in the universe. As the author rightly puts it, the sky is filled with many mirages and mysteries to be explored. The gravitational lenses make the universe into a palace of glasses where one images reflects into multiple images creating an illusory effect. It is curious to know the nature and functions of these gravitational lenses that both help and defy our understanding of the universe. . Gravitational lensing is a budding and promising area of study in astronomy. It helps astronomers to study the dark matters in the universe. It is also useful to investigate the structure of quasars, black holes and find earth like planets around other stars. Â  Gravitational light deflection was identified and accepted, though not accurately. Einstein was doubtful about it though he predicted that a foreground star could magnify the image of a background star as a result of gravitational lensing. More optimistic was the Swiss-American astrophysicist Fritz Zwicky with his predictions on lensing effects of galaxies. At last the speculation came to an end in 1979 when astronomers actually saw evidence of lensing. Generally light that comes from a celestial body goes straight. But when there is any object in between it deflects and the deviation causes many distortions to what we see in the space. It is interesting to note that any thing that possesses mass can serve like a lens. It need not emit light on its own. Four consequences of gravitational lensing are identified. They are: 1.Change of Position, 2. Magnification and Demagnification, 3.Deformation, 4. Multiplication. The perceptible location of star or galaxy changes because of the deflection of gravitational light Secondly, it is also possible to see the magnification of brightness of a star or quasar because of the deflection of light. Sometimes the light demagnifies. Thirdly, galaxies can appear long-drawn-out into arcs or bananas because of the deflection of light. Finally, the multiple images are the result of strong gravitational lensing. How Lensing Works The gravitational –lens system has three components embedded in the space. The distance source of light, an intervening mass that acts as a lens and an observer on the earth are the three which form a straight line. The distant source of light could be a star, quasar, or galaxy. The intervening mass that acts as a lens can be anything from a planet to a black hole. Light travels through the shortest distance, and it need not be a straight line always. Sometimes it can travel through a curve as well. The light bends when it reaches the curved space near a cosmic body. The degree of deflection depends on how close the rays get tot the body and on the mass of the body. The deflect ion angle is directly proportional to the mass and inversely proportional to the closest distance. Gravitational lenses are different from ordinary lenses in many ways. The ordinary lenses have a well-defined focal point whereas the gravitational varieties produce focal lines or surfaces. The typical gravitational lens also causes light rays to experience smaller deflections. The gravitational lensing is achromatic. When the lens system is asymmetric, i.e. when source, lens and observer are not in alignment, the lens has an oblong mass distribution – and the resulting ring breaks up into discrete variegated images. The lens magnifies different parts of the source by different amounts and the highest magnification occurs at caustic. When the alignment is very far off or the lens mass distribution is very spread out, the lensing is very weak. With the discovery of double quasar Q0957+ 561 gravitational lensing became an observable science. So far 64 double, triple and multiple quasars have been found. The CLASS (Cosmic Lens All-Sky Survey) project has mapped more than 10,000 radio sources and 17 multiply imaged systems. To identify whether it is real quasar or an illusion, observes have developed a checklist. They see whether the quasars lie at the same distance, whether their spectra is similar, whether there is any potential lens between the observer and the quasar and whether the brightness of each quasar fluctuates in the same way. When the galaxy lens is spherical it can distribute the light of background quasar or galaxy into a ring or circle called Einstein ring. About a dozen such rings are found. The important application of quasar lensing is to measure Hubble constant, which is a measure of size and expansion rate of universe. Multiple quasars can give insight into cosmological parameter called cosmological constant. It is essential to explain why the expansion of universe appears to be accelerating. The more is the expansion accelerated, the bigger the volume of space. Cosmological constant can not be more than 62 percent of the energy density of the universe. If the density is more, there could be more number of quasars. It supports smaller values of the cosmological constant. Quasars are unsteady by their nature and they tend to brighten and then dim on their own. Â  To distinguish microlensing fluctuations and intrinsic variability astronomers monitor multiple quasar systems. Â  In 1989 astronomers confirmed five multiple quasar systems. They conclude that innermost parts of quasar are hotter and bluer than outer parts. If lens is not single galaxy, but a cluster of galaxies then the image can be a kaleidoscope of strongly distorted arcs and arc lets. Studies on clusters of galaxies reveal that clusters are dominated by unseen dark matter. On an extremely large scale, the vast galaxy clusters of matter tend to be powerful lens. The wide spread shearing of galaxy images support the view that universe is giant cobweb of matter interspersed with voids. The article also focuses on MACHOs and Extra solar planets. MACHOs are collection of rogue planets, dead stars or black holes. However research says that the entire dark matter cannot be made entirely of MACHO. It also notes that stellar mass black holes may cause microlensing events. Stellar microlensing can even detect planets and the extra burst of brightening that might have been caused by planet candidates. Thus, the article ‘Gravity’s Kaleidoscope’ narrates interestingly how the study of illusions can lead us to the discovery of truth relating to celestial bodies in the universe.

Privatization of Electricity in Tanzania :: essays research papers fc

Privatization of Electricity in Tanzania The story of Tanzania, from pre-colonialist period to present Tanzania, located in East Africa, is one of the least developed countries in the world. According to the UNDP Human Development Index, Tanzania ranked 162 out of 177 countries in the 2004 survey (UNDP:2004, HDI), with one being the most developed. According to the Poverty Reduction Strategy Paper (PRSP) prepared by Tanzanian officials for the World Bank, half of Tanzanians 36.6 million people are characterized as â€Å"poor† and one-third live in â€Å"abject poverty†(WB: PRSP p.1). Tanzanians have a life expectancy of 43.5 years, a fertility rate of 5.1 births per woman, an HIV prevalence of 8.8%, and a population growth rate of 1.95% (UNDP: 2004). Agriculture makes up half of the country’s GDP, 85% of the exports, and 80% of the labor force (CIA: 2004). Culturally, Tanzanians are made up of 130 different tribes, each speaking their own mother tongue. The official languages of Tanzania are Kiswahili and English, with English being the main language in commerce, administration, and higher education (CIA: 2004). Kiswahili is a mix of Bantu languages, English, and Arabic, and is indicative of the millennia old history of trade with the outside world. Records of trade routes with the Middle East date back to the 1st century AD (govt web: early history). Zanzibar and the coastal town of Bagamoya were the hubs of the East African slave trade, active for well over a thousand years (pilot). While the early slave trade with the Middle East existed only on a small scale, transporting around 100 slaves at a time, the appearance of Europeans in the 17th century ratcheted up the trade to a much larger scale and level of organization, at its height moving 15,000 slaves a year out of East Africa (pilot). Serious efforts to end the slave trade began in the 19th century, though the trade continued through the German occupation of then German East Africa in the latter part of the century. In 1919 after World War I, Britain took over German East Africa, renaming it Tanganyika, and permanently put an end to the slave trade (govt web: colonial period ). Tanganyika attained independence from British rule in 1961 and Zanzibar followed soon after in 1963, ending the existence of the British mandated territory. Tanzania was formed in 1964 by uniting the mainland, Tanganyika, and the islands of Zanzibar. An excerpt from the Tanzanian National Website displays an interesting official interpretation of the lingering effects of centuries of occupation by foreigners (my emphasis):

One Year MBA Program / Two Year MBA Program Essay

1. Students are requested to go through the instructions carefully. 2. The Assignment is a part of the internal assessment. 3. Marks will be awarded for each Assignment, which will be added to the total marks. Assignments carry equal marks. 4. The completed Assignments of different modules should be bundled together before sending it to the Institute in the address given above or it can be mail to us 2 weeks before the commencement of the examination with the roll number and name of the student. 5. Students who have not received the full set of modules may send the Assignments after receiving the complete set of modules of the semester. 6. Case study project is given based on the Elective Subject selected. Assignments 1. International Law What are your perceptions on the Universal Declaration of Human Rights? Would you like to amend any of the articles or add a new article to the declaration? 2. Strategic Management Select an appropriate generic strategy to position your printing business unit in its competitive environment (map the environment primarily as a pattern of competitive pressures from rivals, suppliers, buyers, entrants and substitutes). 3. Business English

Managing Up Managing Your Boss, Know Yourself, And...

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(Gabarro/Kotter, 1993) In an economic enviro nment where organizations are being downsized and flattened because of industry consolidation and computerization, the benefits of managing up are endless. Managing up and across an organization allows for greater intradepartmental teamwork, cooperation and collaboration on projects, especially when managers are continually asked to do more with less. Most importantly, managing up builds greater trust between the employee and his or her supervisor, expands the employee’s autonomy within theShow MoreRelatedThomas Green: Power, Office Politics and a Career in Crisis Essay2404 Words   |  10 Pagesto the bureaucracy at this level of management. When it comes to work style he is meticulous in details and requires that recommendations and strategies be justified using hard data.    He prefers to stay in a positive mindset in order to keep moral up.   Davis pays much attention to the office politics, strong efforts and enthusiasm of the employee. 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