A skyscraper is a continuously habitable high-rise building that has over 40 floors and is taller than 150 m. The term first referred to buildings with 10 to 20 floors in the 1880s; the definition shifted with advancing construction technology during the 20th century. Skyscrapers may host both. For buildings above a height of 300 m, the term "supertall" can be used, while skyscrapers reaching beyond 600 m are classified as "megatall". One common feature of skyscrapers is having a steel framework; these curtain walls either bear on the framework below or are suspended from the framework above, rather than resting on load-bearing walls of conventional construction. Some early skyscrapers have a steel frame that enables the construction of load-bearing walls taller than of those made of reinforced concrete. Modern skyscrapers' walls are not load-bearing, most skyscrapers are characterized by large surface areas of windows made possible by steel frames and curtain walls. However, skyscrapers can have curtain walls that mimic conventional walls with a small surface area of windows.
Modern skyscrapers have a tubular structure, are designed to act like a hollow cylinder to resist wind and other lateral loads. To appear more slender, allow less wind exposure, transmit more daylight to the ground, many skyscrapers have a design with setbacks, which are sometimes structurally required; the term "skyscraper" was first applied to buildings of steel framed construction of at least 10 stories in the late 19th century, a result of public amazement at the tall buildings being built in major American cities like Chicago, New York City, Detroit, St. Louis; the first steel-frame skyscraper was the Home Insurance Building in Chicago, Illinois in 1885. Some point to Philadelphia's 10-story Jayne Building as a proto-skyscraper, or to New York's seven-floor Equitable Life Building, built in 1870, for its innovative use of a kind of skeletal frame, but such designation depends on what factors are chosen; the scholars making the argument find it to be purely academic. The structural definition of the word skyscraper was refined by architectural historians, based on engineering developments of the 1880s that had enabled construction of tall multi-story buildings.
This definition was based on the steel skeleton—as opposed to constructions of load-bearing masonry, which passed their practical limit in 1891 with Chicago's Monadnock Building. What is the chief characteristic of the tall office building? It is lofty, it must be tall. The force and power of altitude must be in it, the glory and pride of exaltation must be in it, it must be every inch a proud and soaring thing, rising in sheer exaltation that from bottom to top it is a unit without a single dissenting line. — Louis Sullivan's The Tall Office Building Artistically Considered The Council on Tall Buildings and Urban Habitat defines skyscrapers as those buildings which reach or exceed 150 m in height. Others in the United States and Europe draw the lower limit of a skyscraper at 150 m; the Emporis Standards Committee defines a high-rise building as "a multi-story structure between 35–100 meters tall, or a building of unknown height from 12–39 floors" and a skyscraper as "a multi-story building whose architectural height is at least 100 m or 330 ft."
Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high-rises but some other tall structures, such as towers; the word skyscraper carries a connotation of pride and achievement. The skyscraper, in name and social function, is a modern expression of the age-old symbol of the world center or axis mundi: a pillar that connects earth to heaven and the four compass directions to one another; the tallest building in ancient times was the 146 m Great Pyramid of Giza in ancient Egypt, built in the 26th century BC. It was not surpassed in height for thousands of years, the 160 m Lincoln Cathedral having exceeded it in 1311–1549, before its central spire collapsed; the latter in turn was not surpassed until the 555-foot Washington Monument in 1884. However, being uninhabited, none of these structures comply with the modern definition of a skyscraper. High-rise apartments flourished in classical antiquity.
Ancient Roman insulae in imperial cities reached 10 and more stories. Beginning with Augustus, several emperors attempted to establish limits of 20–25 m for multi-story buildings, but met with only limited success. Lower floors were occupied by shops or wealthy families, the upper rented to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven-story buildings existed in provincial towns such as in 3rd century AD Hermopolis in Roman Egypt; the skylines of many important medieval cities had large numbers of high-rise urban towers, built by the wealthy for defense and status. The residential Towers of 12th century Bologna numbered between 80 and 100 at a time, the tallest of, the 97.2 m high Asinelli Tower. A Florentine law of 1251 decreed that all urban buildings be reduced to less than 26 m. Medium-sized towns of the era are known to have proliferations of towers, such as the 72 up to 51 m height in San Gimignano; the medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets.
Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on t
ETH Zurich is a science, technology and mathematics university in the city of Zürich, Switzerland. Like its sister institution EPFL, it is an integral part of the Swiss Federal Institutes of Technology Domain, directly subordinate to Switzerland's Federal Department of Economic Affairs and Research; the school was founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists, serve as a national center of excellence in science and technology and provide a hub for interaction between the scientific community and industry. In the 2019 edition of the QS World University Rankings ETH Zurich is ranked 7th in the world, is ranked 10th in the world by the Times Higher Education World Rankings 2018. In the 2019 QS World University Rankings by subject it is ranked 3rd in the world for engineering and technology, 1st for Earth & Marine Science; as of August 2018, 32 Nobel laureates, 4 Fields Medalists, 1 Turing Award winner have been affiliated with the Institute, including Albert Einstein.
It is a founding member of the IDEA League and the International Alliance of Research Universities and a member of the CESAER network. ETH was founded on 7 February 1854 by the Swiss Confederation and began giving its first lectures on 16 October 1855 as a polytechnic institute at various sites throughout the city of Zurich, it was composed of six faculties: architecture, civil engineering, mechanical engineering, forestry, an integrated department for the fields of mathematics, natural sciences and social and political sciences. It is locally still known as Polytechnikum, or as Poly, derived from the original name eidgenössische polytechnische Schule, which translates to "federal polytechnic school". ETH is a federal institute; the decision for a new federal university was disputed at the time. In the beginning, both universities were co-located in the buildings of the University of Zürich. From 1905 to 1908, under the presidency of Jérôme Franel, the course program of ETH was restructured to that of a real university and ETH was granted the right to award doctorates.
In 1909 the first doctorates were awarded. In 1911, it was given Eidgenössische Technische Hochschule. In 1924, another reorganization structured the university in 12 departments. However, it now has 16 departments. ETH Zurich, the EPFL, four associated research institutes form the "ETH Domain" with the aim of collaborating on scientific projects. ETH Zurich is ranked among the top universities in the world. Popular rankings place the institution as the best university in continental Europe and ETH Zurich is ranked among the top 1-5 universities in Europe, among the top 3-10 best universities of the world. ETH Zurich has achieved its reputation in the fields of chemistry and physics. There are 32 Nobel Laureates who are associated with ETH; the most recent Nobel Laureate is Richard F. Heck, awarded the Nobel Prize in chemistry in 2010. Albert Einstein is its most famous alumnus. In 2018, the QS World University Rankings placed ETH Zurich at 7th overall in the world. In 2015, ETH was ranked 5th in the world in Engineering and Technology, just behind the Massachusetts Institute of Technology, Stanford University, Cambridge University and National University of Singapore.
In 2015, ETH ranked 6th in the world in Natural Sciences, in 2016 ranked 1st in the world for Earth & Marine Sciences for the second consecutive year. In 2016, Times Higher Education World University Rankings ranked ETH Zurich 9th overall in the world and 8th in the world in the field of Engineering & Technology, just behind the Massachusetts Institute of Technology, Stanford University, California Institute of Technology, Princeton University, Cambridge University, Imperial College London and Oxford University. In a comparison of Swiss universities by swissUP Ranking and in rankings published by CHE comparing the universities of German-speaking countries, ETH Zurich traditionally is ranked first in natural sciences, computer science and engineering sciences. In the survey CHE ExcellenceRanking on the quality of Western European graduate school programmes in the fields biology, chemistry and mathematics, ETH was assessed as one of the three institutions to have excellent graduate programmes in all considered fields, the other two being the Imperial College London and the University of Cambridge.
ETH Zurich had a total budget of 1.885 billion CHF in the year 2017. For Swiss students, ETH is not selective in its undergraduate admission procedures. Like every public university in Switzerland, ETH is obliged to grant admission to every Swiss resident who took the Matura. Applicants from foreign countries are required to take either the reduced entrance exam or the comprehensive entrance exam although some applicants from several European countries are exempted from this rule. An applicant can be admitted to ETH without any verifiable educational records by passing the comprehensive entrance exam; as at all universities in Switzerland, the academic year is divided into two semesters. Examinations are held durin
In physics, cryogenics is the production and behaviour of materials at low temperatures. A person who studies elements that have been subjected to cold temperatures is called a cryogenicist, it is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below −150 °C. The U. S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C; this is a logical dividing line, since the normal boiling points of the so-called permanent gases lie below −180 °C while the Freon refrigerants and other common refrigerants have boiling points above −180 °C. Discovery of superconducting materials with critical temperatures above the boiling point of liquid nitrogen has provided new interest in reliable, low cost methods of producing high temperature cryogenic refrigeration; the term "high temperature cryogenic" describes temperatures ranging from above the boiling point of liquid nitrogen, −195.79 °C, up to −50 °C, the defined upper limit of study referred to as cryogenics.
Cryogenicists use the Kelvin or Rankine temperature scale, both of which measure from absolute zero, rather than more usual scales such as Celsius or Fahrenheit, with their zeroes at arbitrary temperatures. Cryogenics The branches of engineering that involve the study of low temperatures, how to produce them, how materials behave at those temperatures. Cryobiology The branch of biology involving the study of the effects of low temperatures on organisms. Cryoconservation of animal genetic resources The conservation of genetic material with the intention of conserving a breed. Cryosurgery The branch of surgery applying cryogenic temperatures to destroy malignant tissue, e.g. cancer cells. Cryoelectronics The study of electronic phenomena at cryogenic temperatures. Examples include variable-range hopping. Cryotronics The practical application of cryoelectronics. Cryonics Cryopreserving humans and animals with the intention of future revival. "Cryogenics" is sometimes erroneously used to mean "Cryonics" in the press.
The word cryogenics stems from Greek κρύο – "cold" + γονική – "having to do with production". Cryogenic fluids with their boiling point in kelvins. Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most used element in cryogenics and is purchasable around the world. Liquid helium is commonly used and allows for the lowest attainable temperatures to be reached; these liquids may be stored in Dewar flasks, which are double-walled containers with a high vacuum between the walls to reduce heat transfer into the liquid. Typical laboratory Dewar flasks are spherical, made of glass and protected in a metal outer container. Dewar flasks for cold liquids such as liquid helium have another double-walled container filled with liquid nitrogen. Dewar flasks are named after James Dewar, the man who first liquefied hydrogen. Thermos bottles are smaller vacuum flasks fitted in a protective casing. Cryogenic barcode labels are used to mark Dewar flasks containing these liquids, will not frost over down to −195 degrees Celsius.
Cryogenic transfer pumps are the pumps used on LNG piers to transfer liquefied natural gas from LNG carriers to LNG storage tanks, as are cryogenic valves. The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. With a background in the heat treating industry, Busch founded a company in Detroit called CryoTech in 1966 which merged with 300 Below in 1999 to become the world's largest and oldest commercial cryogenic processing company. Busch experimented with the possibility of increasing the life of metal tools to anywhere between 200% and 400% of the original life expectancy using cryogenic tempering instead of heat treating; this evolved in the late 1990s into the treatment of other parts. Cryogens, such as liquid nitrogen, are further used for specialty chilling and freezing applications.
Some chemical reactions, like those used to produce the active ingredients for the popular statin drugs, must occur at low temperatures of −100 °C. Special cryogenic chemical reactors are used to remove reaction heat and provide a low temperature environment; the freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and brittle at low temperatures, which makes cryogenic milling an option for some materials that cannot be milled at higher temperatures. Cryogenic processing is not a substitute for heat treatment, but rather an extension of the heating–quenching–tempering cycle; when an item is quenched, the final temperature is ambient. The only reason for this is. There is nothing metallurgically significant about ambient temperature; the cryogenic process continues this action from ambient temperature down to −320 °F. In most instances the cryogenic cycle is followed by a heat tempering procedure.
As all alloys do not have the same chemical constituents, the tempering procedure varies according to the material's chemical composition, t
Bavaria the Free State of Bavaria, is a landlocked federal state of Germany, occupying its southeastern corner. With an area of 70,550.19 square kilometres, Bavaria is the largest German state by land area comprising a fifth of the total land area of Germany. With 13 million inhabitants, it is Germany's second-most-populous state after North Rhine-Westphalia. Bavaria's main cities are Nuremberg; the history of Bavaria includes its earliest settlement by Iron Age Celtic tribes, followed by the conquests of the Roman Empire in the 1st century BC, when the territory was incorporated into the provinces of Raetia and Noricum. It became a stem duchy in the 6th century AD following the collapse of the Western Roman Empire, it was incorporated into the Holy Roman Empire, became an independent kingdom, joined the Prussian-led German Empire while retaining its title of kingdom, became a state of the Federal Republic of Germany. The Duchy of Bavaria dates back to the year 555. In the 17th century AD, the Duke of Bavaria became a Prince-elector of the Holy Roman Empire.
The Kingdom of Bavaria existed from 1806 to 1918. In 1946, the Free State of Bavaria re-organised itself on democratic lines after the Second World War. Bavaria has a unique culture because of the state's Catholic majority and conservative traditions. Bavarians have traditionally been proud of their culture, which includes a language, architecture, festivals such as Oktoberfest and elements of Alpine symbolism; the state has the second largest economy among the German states by GDP figures, giving it a status as a rather wealthy German region. Modern Bavaria includes parts of the historical regions of Franconia and Swabia; the Bavarians emerged in a region north of the Alps inhabited by Celts, part of the Roman provinces of Raetia and Noricum. The Bavarians spoke Old High German, unlike other Germanic groups, they did not migrate from elsewhere. Rather, they seem to have coalesced out of other groups left behind by the Roman withdrawal late in the 5th century; these peoples may have included the Celtic Boii, some remaining Romans, Allemanni, Thuringians, Scirians, Heruli.
The name "Bavarian" means "Men of Baia" which may indicate Bohemia, the homeland of the Celtic Boii and of the Marcomanni. They first appear in written sources circa 520. A 17th century Jewish chronicler David Solomon Ganz, citing Cyriacus Spangenberg, claimed that the diocese was named after an ancient Bohemian king, Boiia, in the 14th century BC. From about 554 to 788, the house of Agilolfing ruled the Duchy of Bavaria, ending with Tassilo III, deposed by Charlemagne. Three early dukes are named in Frankish sources: Garibald I may have been appointed to the office by the Merovingian kings and married the Lombard princess Walderada when the church forbade her to King Chlothar I in 555, their daughter, became Queen of the Lombards in northern Italy and Garibald was forced to flee to her when he fell out with his Frankish overlords. Garibald's successor, Tassilo I, tried unsuccessfully to hold the eastern frontier against the expansion of Slavs and Avars around 600. Tassilo's son Garibald II seems to have achieved a balance of power between 610 and 616.
After Garibald II little is known of the Bavarians until Duke Theodo I, whose reign may have begun as early as 680. From 696 onwards he invited churchmen from the west to organize churches and strengthen Christianity in his duchy, his son, led a decisive Bavarian campaign to intervene in a succession dispute in the Lombard Kingdom in 714, married his sister Guntrud to the Lombard King Liutprand. At Theodo's death the duchy was reunited under his grandson Hugbert. At Hugbert's death the duchy passed from neighboring Alemannia. Odilo issued a law code for Bavaria, completed the process of church organization in partnership with St. Boniface, tried to intervene in Frankish succession disputes by fighting for the claims of the Carolingian Grifo, he was defeated near Augsburg in 743 but continued to rule until his death in 748. Saint Boniface completed the people's conversion to Christianity in the early 8th century. Tassilo III succeeded his father at the age of eight after an unsuccessful attempt by Grifo to rule Bavaria.
He ruled under Frankish oversight but began to function independently from 763 onwards. He was noted for founding new monasteries and for expanding eastwards, fighting Slavs in the eastern Alps and along the River Danube and colonising these lands. After 781, his cousin Charlemagne began to pressure Tassilo to submit and deposed him in 788; the deposition was not legitimate. Dissenters attempted a coup against Charlemagne at Tassilo's old capital of Regensburg in 792, led by his own son Pépin the Hunchback; the king had to drag Tassilo out of imprisonment to formally renounce his rights and titles at the Assembly of Frankfurt in 794. This is the last appearance of Tassilo in the sources, he died a monk; as all of his family were forced into monasteries, this was the end of the Agilolfing dynasty. For the next 400 years numerous families held the duchy for more than three generations. With the revolt of duke Henry the Quarrelsome in 976, Bavaria lost large territories in the south and
An air separation plant separates atmospheric air into its primary components nitrogen and oxygen, sometimes argon and other rare inert gases. The most common method for air separation is fractional distillation. Cryogenic air separation units are built to provide nitrogen or oxygen and co-produce argon. Other methods such as membrane, pressure swing adsorption and vacuum pressure swing adsorption are commercially used to separate a single component from ordinary air. High purity oxygen and argon used for semiconductor device fabrication requires cryogenic distillation; the only viable source of the rare gases neon and xenon is the distillation of air using at least two distillation columns. Pure gases can be separated from air by first cooling it until it liquefies selectively distilling the components at their various boiling temperatures; the process is energy-intensive. This process was pioneered by Carl von Linde in the early 20th century and is still used today to produce high purity gases.
He developed it in the year 1895 after which the process went around seven years as a pure academical process before it was used in industrial applications for the first time. The cryogenic separation process requires a tight integration of heat exchangers and separation columns to obtain a good efficiency and all the energy for refrigeration is provided by the compression of the air at the inlet of the unit. To achieve the low distillation temperatures an air separation unit requires a refrigeration cycle that operates by means of the Joule–Thomson effect, the cold equipment has to be kept within an insulated enclosure; the cooling of the gases requires a large amount of energy to make this refrigeration cycle work and is delivered by an air compressor. Modern ASUs use expansion turbines for cooling; the process consists of the following main steps: Before compression the air is pre-filtered of dust. Air is compressed where the final delivery pressure is determined by recoveries and the fluid state of the products.
Typical pressures range between 10 bar gauge. The air stream may be compressed to different pressures to enhance the efficiency of the ASU. During compression water is condensed out in inter-stage coolers; the process air is passed through a molecular sieve bed, which removes any remaining water vapour, as well as carbon dioxide, which would freeze and plug the cryogenic equipment. Molecular sieves are designed to remove any gaseous hydrocarbons from the air, since these can be a problem in the subsequent air distillation that could lead to explosions; the molecular sieves bed must be regenerated. This is done by installing multiple units operating in alternating mode and using the dry co-produced waste gas to desorb the water. Process air is passed through an integrated heat exchanger and cooled against product cryogenic streams. Part of the air liquefies to form a liquid, enriched in oxygen; the remaining gas is richer in nitrogen and is distilled to pure nitrogen in a high pressure distillation column.
The condenser of this column requires refrigeration, obtained from expanding the more oxygen rich stream further across a valve or through an Expander. Alternatively the condenser may be cooled by interchanging heat with a reboiler in a low pressure distillation column when the ASU is producing pure oxygen. To minimize the compression cost the combined condenser/reboiler of the HP/LP columns must operate with a temperature difference of only 1-2 K, requiring plate fin brazed aluminium heat exchangers. Typical oxygen purities influences the maximum recovery of oxygen; the refrigeration required for producing liquid products is obtained using the Joule–Thomson effect in an expander which feeds compressed air directly to the low pressure column. Hence, a certain part of the air is not to be separated and must leave the low pressure column as a waste stream from its upper section; because the boiling point of argon lies between that of oxygen and nitrogen, argon builds up in the lower section of the low pressure column.
When argon is produced, a vapor side draw is taken from the low pressure column where the argon concentration is highest. It is sent to another column rectifying the argon to the desired purity from which liquid is returned to the same location in the LP column. Use of modern structured packings which have low pressure drops enable argon with less than 1 ppm impurities. Though argon is present in less to 1% of the incoming, the air argon column requires a significant amount of energy due to the high reflux ratio required in the argon column. Cooling of the argon column can be supplied by liquid nitrogen; the products produced in gas form are warmed against the incoming air to ambient temperatures. This requires a crafted heat integration that must allow for robustness against disturbances, it may require additional external refrigeration during start-up. The separated products are sometimes supplied by pipeline to large industrial users near the production plant. Long distance transportation of products is by shipping liquid product for large quantities or as dewar flasks or gas cylinders for small quantities.
Pressure swing adsorption provides separation of nitrogen from air without liquefaction. The process operates aro
Physics is the natural science that studies matter, its motion, behavior through space and time, that studies the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, its main goal is to understand how the universe behaves. Physics is one of the oldest academic disciplines and, through its inclusion of astronomy the oldest. Over much of the past two millennia, chemistry and certain branches of mathematics, were a part of natural philosophy, but during the scientific revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, the boundaries of physics which are not rigidly defined. New ideas in physics explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics enable advances in new technologies.
For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have transformed modern-day society, such as television, domestic appliances, nuclear weapons. Astronomy is one of the oldest natural sciences. Early civilizations dating back to beyond 3000 BCE, such as the Sumerians, ancient Egyptians, the Indus Valley Civilization, had a predictive knowledge and a basic understanding of the motions of the Sun and stars; the stars and planets were worshipped, believed to represent gods. While the explanations for the observed positions of the stars were unscientific and lacking in evidence, these early observations laid the foundation for astronomy, as the stars were found to traverse great circles across the sky, which however did not explain the positions of the planets. According to Asger Aaboe, the origins of Western astronomy can be found in Mesopotamia, all Western efforts in the exact sciences are descended from late Babylonian astronomy.
Egyptian astronomers left monuments showing knowledge of the constellations and the motions of the celestial bodies, while Greek poet Homer wrote of various celestial objects in his Iliad and Odyssey. Natural philosophy has its origins in Greece during the Archaic period, when pre-Socratic philosophers like Thales rejected non-naturalistic explanations for natural phenomena and proclaimed that every event had a natural cause, they proposed ideas verified by reason and observation, many of their hypotheses proved successful in experiment. The Western Roman Empire fell in the fifth century, this resulted in a decline in intellectual pursuits in the western part of Europe. By contrast, the Eastern Roman Empire resisted the attacks from the barbarians, continued to advance various fields of learning, including physics. In the sixth century Isidore of Miletus created an important compilation of Archimedes' works that are copied in the Archimedes Palimpsest. In sixth century Europe John Philoponus, a Byzantine scholar, questioned Aristotle's teaching of physics and noting its flaws.
He introduced the theory of impetus. Aristotle's physics was not scrutinized until John Philoponus appeared, unlike Aristotle who based his physics on verbal argument, Philoponus relied on observation. On Aristotle's physics John Philoponus wrote: “But this is erroneous, our view may be corroborated by actual observation more than by any sort of verbal argument. For if you let fall from the same height two weights of which one is many times as heavy as the other, you will see that the ratio of the times required for the motion does not depend on the ratio of the weights, but that the difference in time is a small one, and so, if the difference in the weights is not considerable, that is, of one is, let us say, double the other, there will be no difference, or else an imperceptible difference, in time, though the difference in weight is by no means negligible, with one body weighing twice as much as the other”John Philoponus' criticism of Aristotelian principles of physics served as an inspiration for Galileo Galilei ten centuries during the Scientific Revolution.
Galileo cited Philoponus in his works when arguing that Aristotelian physics was flawed. In the 1300s Jean Buridan, a teacher in the faculty of arts at the University of Paris, developed the concept of impetus, it was a step toward the modern ideas of momentum. Islamic scholarship inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further placing emphasis on observation and a priori reasoning, developing early forms of the scientific method; the most notable innovations were in the field of optics and vision, which came from the works of many scientists like Ibn Sahl, Al-Kindi, Ibn al-Haytham, Al-Farisi and Avicenna. The most notable work was The Book of Optics, written by Ibn al-Haytham, in which he conclusively disproved the ancient Greek idea about vision, but came up with a new theory. In the book, he presented a study of the phenomenon of the camera obscura (his thousand-year-old